Yeah, like he ever leaves.

Anyway—check out the new story trailer for the PS5 game if you haven’t seen it yet. It looks amazing.

There’s one thing that features heavily in virtually every Wolverine story: his healing factor. It’s legendary in the Marvel Universe (and copied by/transplanted into more than a few other Marvel characters). On the surface, it’s pretty straightforward. Wolverine heals fast. Cuts, gunshots, and stab wounds stitch themselves back together in a relatively short time. And it doesn’t stop there. Logan’s healing factor can handle much larger injuries—horrific burns, the loss of an eye, a bullet through the head, even skin and muscle being ripped or burned away. Stuff that would leave a regular human with nothing left to do but cool to room temperature.

But if we look at Wolverine’s healing factor close up and bring some science into it, his healing factor gets much cooler.

Seriously.

When you work through, step by step, what it does and how it must do it, you eventually reach a strange possibility: Wolverine’s healing factor may not preserve his body at all. It preserves the pattern called Wolverine.

The obvious scientific road to go down is how quickly Logan’s cells divide and rebuild damaged tissue. Yeah, that’s different and interesting (and occasionally gross). But the money question is how those cells know what to build, where to put it, and when to stop.

And then the harder question: if his brain is rebuilt from that same pattern, is the man who wakes up still Logan, or is he a perfect reconstruction who remembers being Logan? Digging into Logan’s healing factor starts scientific, gets really scientific, and then wanders into the metaphysical and existential.

Oh, and don’t worry—we’ll talk about the whole “regenerating from a drop of blood” thing, too.

Yeah. That was nuts.

Subscribe now

“Wolverine Heals.” But What Does That Actually Mean?

You don’t have to search very hard online to find an image of something horrible happening to Wolverine. Take this moment, from about the 1:34 mark in the story trailer above:

It looks like his skin (and quite a bit of muscle) is being flayed away, leaving parts of his adamantium skeleton exposed. Yeah—that’s a bad one. This kind of stuff happens with alarming frequency across nearly every medium in which Wolverine appears.

Like after he lost a fight to Gambit in Ultimate X-Men #51:

Or when he was shot in the head by William Stryker in X-Men Origins: Wolverine with an adamantium bullet…

Or the time he survived an atomic bomb in The Wolverine…

Or when Dark Phoenix burned away most of his flesh…

Or when Magneto ripped the adamantium out of his body in X-Men ‘97, s1e9…

Or he loses a hand. Or an eye. Or gets run over by a steamroller (true! Wolverine and the Punisher have beef…). Or has his flesh completely burned away. Or has enough tissue chopped and sliced off that an ordinary person would be dead long before hitting the floor.

Okay, okay—we’re not going to turn this into a catalog of every weird and horrible thing Wolverine has survived. Plenty of other sites that have already done that.

Side note: Yes, there are far more extreme examples than these (he had his head removed one time back in the day for cryin’ out loud). The early ‘00s especially were a weird time with comic creators one-upping each other for the horrible things they could do to Wolverine. We’re going to keep things …well, extreme, but not crazy like some of the really rough stuff.

We know what happens next. The wounds close, everything grows back, and Wolverine is mostly okay.

But those deceptively simple visuals, along with our expectation of what comes next, hide the cool stuff.

When Wolverine heals, his body doesn’t just produce more cells. That would be somewhere between kinda helpful and useless. Instead, Wolverine’s body rebuilds (just a few examples):

• The right bones in the right order

• Joints bending in the right direction

• Muscles connected to the correct tendons

• Blood vessels that connect to the existing circulation

• Nerves that find their original destinations

• Skin with the right shape, thickness, and orientation

• An eye whose many layers line up well enough to see

And then it stops.

Wolverine’s healing factor is usually presented as a matter of speed. His wounds close faster. His bones mend faster. Missing tissue grows back faster, and he’s ready to get back into the fight. But the speed with which he heals may be the least interesting thing about it.

The remarkable thing is that Wolverine always grows back into Wolverine.

So how does his body know what Wolverine is supposed to look like?

Now we’re talking the difference between healing and regeneration. Spoilers: one, we can do; the other…not so much, and certainly not as well.

Share

Faster Healing Isn’t Enough

In our world (not part of the Marvel Universe), human healing prioritizes survival, not perfect restoration. Stop the bleeding. Close the wound. Fight the infection. Clear away the wreckage. Stabilize whatever remains.

All in all, it’s an amazing system, and absolutely necessary for our survival. When any part of it goes wrong, the consequences can range from a wound that refuses to close to chronic illness, runaway scarring, or death.

But our bodies often leave stuff behind when they repair the damage:

• Scar tissue

• Bones that knit together out of alignment

• Tendons weakened or bound by scar tissue

• Tissues stuck together by adhesions

• Dirt, glass, or other debris sealed inside the body

• Nerves that never find their way back to the main line

You occasionally hear people say that an injury or a wound “Didn’t heal right.” That’s because it’s easy to confuse healing with regeneration. Again, we do one, but the other…meh?

And just stepping on the gas of our normal wound-healing process could make everything worse. A dislocated shoulder could lock itself into place while it’s still dislocated. A wound could close around glass, dirt, a bullet, or scraps of clothing. A severed tendon could retract into the arm and scar into the wrong place. The body did its best. Here’s a sticker.

Human bodies are remarkably good at emergency repair. Wolverine’s “healing factor” has to close the wound, replace what was lost, and restore the model back to factory settings.

They’re not the same thing.

And that’s what should make any human doctor in the Marvel Universe go:

And then say:

“Okay. I’m going to need some blood, a tissue sample, three MRI scans, and the most aggressive informed-consent form ever written.”

Putting it this way, it’s no wonder that so many people want to get their hands on Logan and see what makes him tick. Yeah, yeah, Weapon X, mutant exploitation, crimes against humanity. But still…the medical breakthroughs.

Does that make me sound like Mr. Sinister?

I think it makes me sound like Mr. Sinister.

Actually, this may be more Dr. Cornelius and Weapon X than Mr. Sinister.

Is it still evil if we get informed consent?

Anyway…

Regeneration isn’t impossible in our universe. Humans do limited versions of it, and a few animals are genuinely Wolverine-level spectacular at it. We can look at them as examples of how regeneration might work with Wolverine.

Let’s go with the crowd-pleaser in that latter category: axolotls.

Subscribe now

The Uncanny Axolotls

This is an axolotl:

Salamanders native to the lakes and canals around Mexico City, axolotls look like Pokémon designed by a committee of eight-year-olds. The feathery branches sticking out from their heads are external gills. The little smile? That’s just how their faces work. Cute? Absolutely. But underneath all that pink, frilly charm is one of the coolest regenerative systems in the animal kingdom.

When an axolotl loses a hand (the horror! It’s so cute!), cells near the injury form a temporary regeneration zone called a blastema. The blastema is the fancy term for a group of undifferentiated cells that can proliferate and regenerate missing body parts. Its cells can divide, reorganize, and rebuild what is missing.

They don’t grow a random lump of generic axolotl cells; they regrow exactly what was missing.

For example, the blastema on the axolotl’s stump produces:

• A wrist

• The correct number of digits

• The correct orientation

• Bone, muscle, nerves, vessels, and skin

• Only the portion of the limb that was lost

Cut the limb near the wrist, and it regrows a hand—not an entire arm.

Axolotls can do this because their cells remember where they are. It’s not a literal architectural drawing stored in one location like a blueprint, though. Instead, cells carry positional information needed for rebuilding, like:

• I am near the end of the forearm.

• This is the front.

• That is the thumb side.

• These tissues should be beside me.

• Something is missing beyond this point.

The cells communicate through gene activity, chemical gradients, electrical signals, physical contact, nerves, and the surrounding extracellular matrix.

The reasoning behind this ability for axolotls dates back to their development. Generally, the cells of all organisms in development have an idea of who they’re going to be and where they should go. Regeneration in axolotls is studied because they’re relatively unique. The connective tissue cells in axolotls hold on to specific information assigned when the limb first developed. That information and developmental pathways can be reactivated when the animal is injured.

Side note: You may have heard that the regeneration in axolotls is due to them remaining functionally larval throughout their entire lives. That’s not entirely true. While they retain many larval characteristics, they mature and become adult axolotls while maintaining their regenerative abilities. They’re not “forever babies” as adults; they can tap into their original developmental programming.

Being an axolotl doesn’t make you amphibian Wolverine, though. There are limitations.

The positional memory of cells appears to be located mostly in connective tissue cells (such as fibroblasts), while muscle cells can mostly make more muscle cells, Schwann cells (part of the nervous system) produce Schwann cells, and other cells are likewise limited in their regeneration capabilities. In many ways, connective tissues have the overall plan, while other cells are like specialized construction teams that can only make those types of cells.

Once the axolotl is injured, specific signals are sent through the cells near the affected area. A currently researched example is along the axis of an axolotl hand, from the thumb to the little finger.

In the area, posterior connective-tissue cells retain the activity of a developmental on/off switch protein called Hand2. Following an injury, Hand2 turns on a crucial growth signal called Sonic Hedgehog (Shh) to regrow the missing limb. Together, Hand2 and Shh (and other factors) make a map that tells the growing tissue where to grow a thumb versus where to grow a pinky, making sure the new limb looks just like the old one.

The entire system is known by pieces. There’s no whole-organism cellular GPS that can be located and tracked within axolotls. And there are lots of caveats and considerations that prevent larger assumptions from being made, willy-nilly.

Just a couple of quick final things before this turns into a molecular biology/developmental biology lecture and we forget that we started this talking about Wolverine...

Share The Science Of...

The Hand Does Not Grow a New Body

The positional memory shown by some axolotl cells is not a complete backup copy of the whole creature. It tells what cells belong near the current location, and that’s it. You may be thinking of starfish. Completely different thing with its own caveats.

Consider the detached axolotl hand. It’s lost its blood supply (no oxygen, no nutrients or waste removal), so the tissue will die. Limb regeneration is directional - a wrist stump regrows a hand away from the body; the hand stump can’t grow a body away from the hand. The regrowth system needs a living wound environment. Hand cells keep their positional identity and aren’t going to change into arm cells, trunk cells, or head cells. And finally, an axolotl is not a planarian. Those flatworms can do the whole, new-body thing. Creepy and cool.

Also…

Axolotls Are Not Immortals

But they may live longer thanks to their unique biology - but it’s not the regeneration that does it. Regrowth is specific; aging is whole-body. Axolotls still get sick, suffer from lousy environments, get organ failure, and can be injured past the point of no return.

But they do appear to be resistant to some aspects of getting old. But that may be related to creating new tissue through regeneration, rather than regeneration freeing them from aging. The research is limited, and the jury is still out.

The TL; DR of all of this side quest? Axolotls form blastemas, blastemas are pretty amazing, and humans don’t form them at injury sites. But Wolverine might have something like it.

Hey - his name is in the title. Let’s get back to Wolverine…

What Have We Learned About Logan?

If we model what Wolverine’s healing factor does on known biology, then he is a little axolotl-like. His cells don’t need to remember all of Wolverine. Each one only needs to remember where it belongs in Wolverine, and recognize when its neighbors are missing.

This is far more than what axolotls can do, which makes for great stories, but envious axolotls.

Let’s apply what we’ve learned a little. Suppose Logan loses a hand.

His surviving wrist cells encounter an anatomical impossibility: tissues that should have neighbors beyond them now face open air. The pattern has been interrupted.

His healing factor could proceed like this:

1. Detect the broken anatomical pattern.

2. Temporarily seal and protect the wound.

3. Create a blastema-like regeneration zone.

4. Establish the body’s axes: front/back, left/right, near/far.

5. Grow the missing tissues according to their positional addresses.

6. Reconnect vessels, muscles, tendons, and nerves.

7. Stop when all of the anatomical mismatches have been eliminated.

Some of the things on this list have analogs in our world’s animals, but some are still wish-list items. The best way to think about it is Wolverine’s healing factor is a mishmash of a handful of different features we see across a variety of organisms.

(And no, we’re not going to go into how he gets adamantium back, because…??? Is there a precedent for that in comics? If he loses a leg and it grows back, adamantium-free, does he have to go in for Weapon X-style “treatment” again? Who does it? Why would he chose that? It seems like it hurts.)

Turns out that the best metaphor for Wolverine’s healing factor isn’t a static blueprint. It’s an error-correcting network.

Wolverine’s body continually compares what is there with what should be there. An injury creates a discrepancy. Regeneration continues until the discrepancy disappears.

Or, more simply:

Logan’s body doesn’t stop growing after an injury because his body has produced a predetermined number of cells. He stops because there are no anatomical errors left to correct.

Side note: the error-correcting network idea also allows for Wolverine’s immune system - he doesn’t get sick, his lungs don’t suffer from the cigars he smokes, his liver is fine, despite the beer. This guy is made for hard living.

This lets us inventory what his “healing factor” actually includes:

• Injury detection

• Scarless wound closure

• Cellular reprogramming

• Rapid but controlled cell division

• Positional memory

• Three-dimensional pattern formation

• Blood-vessel reconstruction

• Nerve reconnection

• Cancer (cell overgrowth) suppression

• A reliable stop mechanism

Yeah, “fast healing” is almost the least interesting item on this pretty-amazing list.

Bringing this into reality, we already have a limited version of this in our bodies: the liver. Remove part of a healthy human liver, and the remaining tissue grows until the body has roughly the amount of functioning liver it needs. It doesn’t count out a predetermined number of new cells. It responds to a deficit, and stops when that deficit has been corrected.

The catch is that the liver restores capacity, not the original architecture. Logan does both.

But hear me out…

What Counts as Wolverine?

If your body has an error-correcting mechanism hiding under the name “healing factor,” you’re going to have some deep questions.

The healing factor can’t just restore his genetically encoded body, because Logan now has some other features: an adamantium skeleton, memories, scars, and age, to name a few. To do what it does, Logan’s body has to somehow distinguish change from actual damage.

Along with repairing anatomy, Logan’s healing factor must continually decide what makes up “Logan” and what doesn’t.

Start stroking your chin now. There are some things to consider:

First, what pieces of Logan get priority for regrowth? If every fragment of Logan’s DNA contains the “whole Logan rebuild” protocol, then DNA can’t be the determining factor for which piece gets to rebuild the whole person. Every cell may have the blueprint, but not every cell gets to be Logan. Otherwise, every bloodstain and severed finger becomes another Wolverine.

Wolverine’s healing network therefore needs:

• One surviving fragment designated as “original”

• A hierarchy among tissues

• A way to distinguish “Logan” from “material formerly attached to Logan”

The brain and upper spinal cord remain the best biologically defensible organizing center when we look at this from a reasonable science perspective. Yes, as mentioned earlier, creators have occasionally pushed his survival beyond what that model allows.

Second deep Wolverine thought - information. A brain is not a mind.

Regeneration covers the brain rebuild — missing cells report that there are cells missing, and everyone starts to rebuild what was there before. Will that rebuild reconstruct the exact neural organization that was there before? The organization and connections between neurons help form memories, behaviors, habits, instincts, and more. Without those connections, they’re just not there.

And the deeper question - how does Logan’s healing factor preserve the continuity of consciousness given a traumatic brain injury? More than memories, now we’re into the realm of identity, personality, connection to others. The movies have touched on this a bit - the brain damage of being shot in the head with an adamantium bullet was responsible for his memory loss, which Professor Xavier helped him recover, but repeated head injuries? Logan does have memory issues, so this could actually be the underlying reason. Parts of his brain are so damaged that his healing factor rebuilds them, but the connections don’t reconnect. Memories are gone.

Continual severe damage to Logan year after year really brings up a “Logan of Theseus” question. How much can you replace and still have Logan, rather than a human who thinks he’s Logan? Wolverine gets a huge head injury and is out for days. Who wakes up?

Subscribe now

The Cost of Being Wolverine

In any universe, there’s no free lunch. Everything costs something.

Let’s apply that idea to Wolverine’s healing factor. It’s constantly checking and updating matter and structure in the body, as well as maintaining information, that is, keeping the pattern that makes the body “Logan.”

Short phrases, but that’s a lot of energy expenditure.

Let’s run a list of what the healing factor has to be doing for it to work as we’ve seen it work. Its list of jobs includes:

• Producing new cells and proteins

• Copying DNA

• Rebuilding membranes, bone, muscle, vessels, and nerves

• Pumping blood through new tissue

• Removing dead material and metabolic waste

• Preventing infection

• Regulating temperature

• Suppressing cancer

• Continually repairing toxins, radiation damage, oxidative damage, and ordinary cellular wear

• Maintaining or reconstructing neural information

24/7/365

Recovering from catastrophic injury cannot be free. Logan needs energy, raw materials, and very specific instructions.

Yes - I am aware that I’m talking about needing raw materials for someone who lives in the same universe as the Hulk, who can add to his mass whenever he gets all huffy. I know, but go with me here. There’s a sad ending coming up.

Tweak things for Logan towards the realistic, and we’ve got a recently-healed Wolverine who’s ravenously hungry, dehydrated, oxygen-starved, overheated, out of stored fat and glycogen, and running low on whatever was needed to rebuild the missing tissues (calcium, iron, etc). And it does it again in an hour. And an hour later, if the Sentinels push their assault.

(Let’s not get into his occasional dalliances into self-cannibalization…energy-wise? Nope. That would not work. Also - gross.)

What I’m getting at here is that the healing factor has an endpoint.

And that Logan is one of the best Wolverine stories ever.

Why Wolverine’s Healing Factor Fails in Logan

In Logan, we saw an aging Wolverine, knowing that his end was coming.

Well, yeah. He cannot live forever. He’s not Superman.

Any modestly realistic maintenance system is going to gradually get slower and lose the race against accumulated damage. For decades, Logan’s system has been working to correct regular cellular damage, repeated catastrophic injuries, toxin exposure, adamantium poisoning, and just the wear and tear on his body from living as long as he has.

Logan’s body has spent a lifetime continuously correcting itself back into Wolverine. By the time of Logan, the errors are arriving faster than they can be corrected. Aging is what happens when error-correcting becomes imperfect. Even if we go with the idea of the healing factor healing itself, we’ll end up going down the same road eventually.

Death is when the system cannot cross the gap between what is there and what should be there. Eventually, remaining Wolverine costs more than Wolverine can pay.

And in the film, we saw Logan, a warrior until the very end, coming to terms with this and choosing to end his story on his own terms.

Keeping Wolverine, Wolverine

In the end, Wolverine’s healing factor isn’t just accelerated wound repair. For it to work as we’ve come to see over the past 50+ years, it’s his entire body engaged in unending self-preservation, not just keeping him alive, but rebuilding the boundary between Logan and everything that’s trying to turn him into something else. The mutation isn’t about just repairing his body; it’s about preserving the pattern we call Wolverine.

It’s an amazing mutation, loaded with possibilities and potential for incredible stories and scenes, and it’s also a springboard, as we’ve used it here for thinking about science and deeper topics.

And it has an endpoint. Bodies can’t regrow and heal forever. But instead of taking the fun out of it, working through his healing factor adds more than it takes away and makes Logan’s story long and rich, full of possibilities and opportunities until the final page is written.

Got a favorite example of Wolverine’s healing factor not mentioned here? A story I need to know about where identity gets a mention with the whole healing process? Let me know in the comments!

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. It’s re-presented here because it’s useful, weird, fascinating, updated, or some combination of the four. This piece was heavily updated to reflect the Avengers: Doomsday connection and updated science since its original publication.

The Marvel Cinematic multiverse is about to have a terrible, horrible, no good, very bad day.

In Avengers: Doomsday, heroes from three different universes are set on a collision course. Then comes Secret Wars a year later, where (if the movie borrows even loosely from the comics) the walls separating those universes may come down altogether, leaving the MCU with one, streamlined universe.

Before Doctor Doom starts mashing realities together, we should probably settle a fairly important question:

What exactly is a “universe,” and what do physicists mean when they say there might be more than one?

There was a time when the multiverse was specialized knowledge shared mostly by comic-book fans (“Flash of Two Worlds” and everything after, yo) and theoretical physicists. There’s a combination for you. Now everyone knows what a multiverse is.

Or thinks they do. No shade meant, my nerds.

Marvel uses universe, timeline, dimension, world, and reality as though all five words came free in the same box. In Avengers: Endgame and Loki, timelines branch when events unfold differently. Elsewhere, parallel universes appear to exist independently, complete with their own histories and inhabitants. And in Doctor Strange in the Multiverse of Madness, entire universes can collide in events called incursions.

Those are not alternate names for the same thing. They are different ideas wearing one very large multiverse trench coat.

This is going to be a deep dive, so buckle up.

So What Counts as a Universe?

Let’s start with the least exotic kind of multiverse, the one that may not be a multiverse at all. The one we can see.

We can see only the parts of the cosmos whose light has had time to reach us. That region is called the observable universe, and it extends roughly 46 billion light-years in every direction.

Wait. The universe is about 13.8 billion years old. How can we see something 46 billion light-years away?

Because the universe expanded while the light was traveling. The objects that emitted the oldest light we see were much closer when that light began its journey. Space stretched. They are now much farther away.

But the edge of the observable universe isn’t the edge of anything physical. There’s no wall there. No drop-off. It’s simply the farthest boundary from which light has been able to reach us.

Beyond it, there may be considerably more universe.

Not another universe, necessarily. Just more of this one.

Picture the cosmos as an enormous quilt in a dark room. The observable universe is the circular patch illuminated by our flashlight.

Move the flashlight, and you reveal a different patch. Move it only a little, and the two circles overlap. Move it far enough, and you uncover a region containing galaxies whose light has never reached us—and may never reach us.

Cosmologist Max Tegmark calls this a Level I multiverse, although the name makes it sound more exotic than it is. These regions wouldn’t have different laws of physics, extra dimensions, or evil versions of you with sinister facial hair. They would simply be unimaginably distant parts of the same cosmic quilt.

The universe may continue far beyond the patch we can see. It may even continue forever.

And if it does, things start getting weird again.

An infinite universe contains an infinite amount of stuff—but infinity alone does not guarantee another Earth.

For that, we need a few additional assumptions. Matter must be spread more or less uniformly across the larger cosmos. A region the size of our observable universe must have only a finite number of possible arrangements. And those arrangements must be distributed with enough randomness that, given infinite space, they eventually begin to repeat.

If all of that is true, then somewhere beyond the cosmic horizon is another Earth.

Keep going, and there should be another you. Then another. There’s a variation of you who became a physicist. A you who speaks German. A you with a deeply regrettable mustache. And eventually, you’re sitting on their device, reading this exact same sentence while another version of me wrote it.

Infinity is weird.

These wouldn’t be alternate timelines created when someone made a different decision. They would be ordinary collections of matter, unimaginably far away, that happened to fall into familiar arrangements.

How far away?

Tegmark estimated that the nearest region containing a person identical to you might be about 10^{10^29} meters away.

That number is not a typo. It is a 1 followed by roughly 100 octillion zeroes.

So yes, another you may be out there.

No, you are not going to visit.

Share

Universes Blowing Bubbles

So far, our “multiverse” has consisted of distant regions of one enormous (and possibly infinite) universe. But what about just… “more” universes?

Actually, there is a way to make those. Theoretically.

To cook up more universes, we have to go back to a tiny fraction of a second after the Big Bang, when the infant universe may have undergone an extraordinarily brief period of expansion called cosmic inflation.

“Extraordinarily brief” barely begins to describe it. Inflation may have begun around 10^-36 seconds after the Big Bang and ended by roughly 10^-32 seconds after. During that sliver of time, space expanded by a crazy amount.

Physicist Alan Guth proposed inflation in 1981 to explain several suspicious things about our universe: why it looks so nearly flat, why distant regions have almost the same temperature even though they appear never to have been in contact, and why the cosmos is so remarkably uniform on its largest scales.

Inflation smooths those problems out—almost literally. Take a tiny, wrinkled scrap of spacetime and stretch it violently enough, and the part you can see begins to look flat and even.

But some versions of inflation come with an unexpected complication: inflation may not have ended everywhere at once.

In one region, inflation stops. Its energy transforms into matter and radiation, producing a hot, expanding cosmos like ours. Elsewhere, inflation continues, stretching space at a staggering rate. Then it stops in another region. And another.

Each region where inflation ends becomes what cosmologists call a bubble universe or pocket universe.

The larger inflating space keeps producing bubbles while also expanding fast enough to make room for still more bubbles.

It’s a universe factory whose factory floor grows faster than it can fill it.

The bubble image is useful; try to resist going too far with the metaphor. These universes aren’t soap bubbles floating through some larger cosmic room. That would require an even bigger room, followed immediately by the question of what that room is sitting in, and now we’ve ruined everyone’s afternoon.

A bubble universe is a region of spacetime where inflation has ended. Its “outside” is still-inflating spacetime, expanding so rapidly that neighboring bubbles may remain permanently separated even while each grows enormously on the inside.

Depending on the model, different bubbles could also settle into different physical states. The fundamental forces might have different strengths. Particles might have different masses. The cosmological constant might be larger, smaller, or catastrophically unfriendly to the formation of stars, planets, and anything else.

The underlying physics would still come from the same larger theory. But each bubble could be running that physics with different settings.

Now for the part Doctor Doom would care about:

Bubbles might collide.

Not with planets slamming together along a glowing seam in the sky. A collision would disturb the structure of spacetime where the bubbles met. Some models predict that such an ancient collision could leave a circular scar in the cosmic microwave background—the oldest light in the universe.

Scientists have looked for those scars.

So far, they haven’t found a convincing one.

Bubble universes therefore give Marvel something it desperately wants: distinct universes that can, at least theoretically, collide.

Subscribe now

Every Outcome Happens - Maybe

Bubble universes give Marvel separate universes. But they don’t give it the branching timelines of the Time Variance Authority.

For those, we need quantum mechanics.

This is the territory Marvel enters in Avengers: Endgame, Loki, and What If…? A decision changes. An event unfolds differently. The timeline branches, producing another reality in which Loki escapes with the Tesseract, Peggy Carter receives the super-soldier serum, or Doctor Strange makes an extremely unfortunate romantic decision several thousand times.

It’s wonderfully clean storytelling.

The physics is not that considerate.

In 1957, graduate student Hugh Everett III proposed what he called the relative-state formulation of quantum mechanics. The name “Many-Worlds Interpretation” came later, but it captured the part everyone noticed:

When a quantum event has several possible outcomes, the universe does not choose one and discard the others.

They all happen.

In the usual simplified account of quantum mechanics, a particle can exist in a combination of possible states called a superposition. Measure it, and that superposition appears to collapse into one definite result.

Everett’s big move was to remove the collapse.

The quantum state continues evolving, with each possible result represented in a different branch. In one branch, the detector records one outcome. In another, it records the other. An observer becomes part of that branching process, seeing a definite result in each branch while remaining unaware of the others.

Nobody has to bomb the Sacred Timeline. The universe does all the branching itself.

This is where Schrödinger’s cat gets dragged into the box.

The cat is sealed inside with a radioactive atom, a radiation detector, and a mechanism that releases poison if the atom decays. Quantum mechanics allows the atom’s undecayed and decayed states to exist in superposition. Connect those states to the machinery and the cat becomes entangled with them:

Atom intact. Cat alive.

Atom decayed. Cat dead.

Schrödinger devised the thought experiment to show how ridiculous quantum superposition becomes when extended to an entire cat. He was making a point, not proposing an exciting new method of pet ownership.

In a collapse interpretation, opening the box yields a single definite result. In Many Worlds, nothing collapses. The cat, the detector, the box and eventually the person opening it all become entangled in the larger quantum state. One version of the observer finds a living cat. Another finds a dead one.

But the observer’s decision to open the box does not create the branches. Consciousness isn’t the trigger. The cat does not wait in quantum limbo until somebody bothers to look.

The crucial process is decoherence.

Quantum systems do not remain politely isolated. They interact with air molecules, light, heat and everything else around them. Information about their possible states spreads into the environment. The alternatives rapidly lose their ability to interfere with one another and begin behaving like separate, effectively classical histories.

This happens constantly and unimaginably quickly. There is no cosmic alarm that sounds when Loki picks up the Tesseract. No judge deciding that one choice is important enough to qualify as a Nexus Event.

Marvel has the order backward. Loki’s decision doesn’t make the universe branch. If Many Worlds is correct, the quantum processes inside Loki, the Tesseract, the floor beneath them, and every photon bouncing around the room have already been producing an extraordinarily complicated branching structure.

By the way, the branches don’t all peel off and get sorted and stored. Remember, we’re in a single universe (think of the bubbles). All the branches remain parts of the same universe, but are separated within an abstract mathematical realm called Hilbert Space.

The dramatic choice is merely where the writers decide to start paying attention to the event that causes a split, and what’s different in that timeline.

And that creates a fairly serious problem for Marvel.

Once those branches decohere, they are not supposed to remain neighboring roads that someone can revisit with the right wrist-mounted gadget.

The TVA treats branching timelines like physical roads. Agents step from one to another using TemPads. Reset Charges prune unwanted branches. The Time Loom organizes the survivors. By the end of Loki season 2, the whole collection of timelines can be gathered up and held like the glowing roots of an extremely consequential tree.

That is excellent television.

It is not Many Worlds.

An Everett branch is not a miniature universe sitting beside ours at a slightly different cosmic address. The branches remain parts of one universal quantum state. Decoherence prevents their different outcomes from producing observable interference, making each branch behave as though the others no longer exist.

“As though” matters.

Share The Science Of...

Quantum mechanics is reversible at its foundations. The information connecting the branches is not necessarily destroyed; it has been dispersed into the environment. In principle, interference could be restored if every interaction responsible for the decoherence were precisely reversed.

All you would have to do is locate and control every air molecule, photon, vibration and particle that carried away information about the event, then return every one of them to exactly the right quantum state.

So: easy.

For a carefully isolated electron, scientists can preserve or recover interference. For Loki, the Tesseract, the room around them and the rest of the universe, the required information has spread so far and become entangled with so many particles that reversing the process is effectively impossible.

A TemPad would not merely need to locate another timeline. It would have to reconstruct and manipulate the quantum state of an entire macroscopic history.

Pruning creates another problem. Many Worlds preserves every outcome through the continuous evolution of the universal wavefunction. It offers no mechanism for deleting one branch while leaving the others untouched.

Marvel apparently noticed at least part of this problem. Loki eventually reveals that pruning does not actually erase matter. It dumps the pruned objects—and people—into the Void at the end of time.

The TVA is not destroying timelines. It is taking out the multiversal trash.

And none of this gives us an incursion. Everett branches are not objects floating beside one another in space. They do not have surfaces that can collide, planets that can overlap, or boundaries Doctor Strange can accidentally weaken.

Many Worlds gives Marvel all the alternate outcomes it could ever want.

It just won’t let Marvel visit them.

We know branches can affect one another before decoherence completely separates them because quantum alternatives can produce interference. That brings us to the most famous experiment in quantum mechanics: Young’s Double-Slit Experiment.

The experiment begins with a wall containing two narrow slits and a detecting screen behind it.

Fire ordinary particles at that wall—tiny BBs, say—and you expect two clusters on the screen. Some pass through the left slit. Some pass through the right. Two slits. Two bands. Completely reasonable.

Light, electrons, and other very small pieces of stuff refuse to be that cooperative.

Send light through both slits, and it spreads outward in overlapping waves. Where the crests meet, they reinforce one another. Where a crest meets a trough, they cancel. The screen shows an interference pattern: alternating bright and dark bands.

Fine. Light is a wave.

Except light also arrives at the screen in individual packets called photons.

So turn the source down. Send the photons through one at a time.

Each photon arrives at one specific point. A dot appears on the screen. Then another. And another. At first, the dots look random.

Keep going.

Slowly, the interference pattern returns.

One photon at a time, the universe draws a wave pattern.

That should bother you at least a little.

There is never a second photon traveling beside the first, giving it something to interfere with. Each photon behaves as though both possible paths, the left slit and the right, contribute to where it eventually lands.

This is not a tiny particle secretly checking both hallways like a TVA agent looking for the correct Loki. Quantum mechanics describes it using a wavefunction that contains amplitudes for both paths. Those amplitudes meet on the far side of the barrier and interfere, changing the probability that the photon will appear at each point on the screen.

The photon still arrives as one dot.

But the pattern formed by thousands of those dots contains information from both possible paths.

Now place a detector at the slits that can determine which path the photon took.

The interference pattern disappears.

This is usually described as the photon “knowing it is being watched,” which is a wonderful sentence if your goal is to make quantum mechanics sound haunted.

But the photon knows nothing. A conscious observer is not required. The detector must physically interact with the photon to record which-path information. That interaction entangles the photon with the detector and its surroundings. The two paths become distinguishable, decoherence takes over, and the interference is lost.

In Marvel terms, the alternatives can affect the same outcome only while they remain part of the same coherent quantum story.

Once the universe has recorded enough information to distinguish “photon went left” from “photon went right,” the alternatives stop behaving like two Avengers teaming up in the same third-act battle. They become separate histories that can no longer coordinate.

Many Worlds offers one way to understand what happened. The wavefunction never collapses. Both alternatives remain within the total quantum state, and their amplitudes produce the interference pattern while they are still coherent.

But this is not evidence that two fully formed universes briefly opened portals and fired photons at one another. These are quantum alternatives within a single experiment, before environmental interaction has separated them into effectively independent branches.

The double-slit experiment therefore shows us something stranger—and more restrained—than Marvel’s multiverse.

Reality can contain several possible paths at once. Those possibilities can interfere. And from that interference, one definite dot appears on a screen.

Then we do it again.

And again.

And probability slowly becomes a picture.

Two Universes Walk Into…Each Other

Many Worlds gives Marvel branching realities but refuses to let them collide.

For that, we need something with a little more structural integrity.

We need branes.

The name is short for membranes, although these are not necessarily thin, floppy sheets. In string theory, a brane can have different numbers of spatial dimensions. A zero-brane is pointlike. A one-brane resembles a string. A two-brane resembles a sheet.

Our universe could—in some highly speculative models—be a three-brane: three dimensions of space embedded within a larger, higher-dimensional spacetime called the bulk.

Picture two slices of bread in a loaf. Each slice is its own three-dimensional universe. The loaf provides an additional dimension separating them.

Yes, a slice of bread is two-dimensional, and our universe has three spatial dimensions. Analogies sometimes arrive missing a dimension. We work with what we have.

Everything we know- atoms, planets, stars, Avengers- might be confined to our brane. Light could travel across it but not leave it, which would make another brane invisible even if it were nearby in the higher-dimensional bulk.

Gravity might be different. In some braneworld models, gravity can extend into the bulk. Its strength could appear weaker to us because it is spreading through dimensions the other forces cannot enter.

That idea is speculative. We have no evidence that our universe is a brane, no confirmed extra spatial dimensions, and no detected gravitons wandering off into the bulk.

But branes give Marvel something the other models could not:

Two entire universes can exist near one another without sharing the same space.

And if they can move through the bulk, they can potentially collide.

Now we have something that begins to resemble an incursion.

Begins to.

Because when branes collide, Earth-616 does not appear in the sky above Earth-828 while both versions of New York fight over the same parking spaces. In some ekpyrotic and cyclic models, the collision releases tremendous energy and produces conditions resembling a hot Big Bang.

Side Note: We’ve talked before about how our universe doesn’t show any solid evidence for being cyclic, back when we discussed Galactus’ origin story.

In Secret Wars (the comic series…) Marvel’s incursions can end a universe.

A brane collision might begin one.

Marvel’s incursions borrow the collision and leave behind almost everything else.

In Doctor Strange in the Multiverse of Madness, Reed Richards explains that an incursion can begin when someone from one universe spends too much time in another. The boundary between the universes erodes. They collide. One or both may be destroyed.

Apparently, the multiverse has an immune system, and Doctor Strange is a particularly aggressive infection.

But what does it mean for two universes to collide?

If they are completely separate spacetimes (bubbles), Earth-616 and Earth-828 do not occupy different locations. They each contain their own locations. “New York” exists inside both universes, but the two cities cannot crash into one another any more than two people standing on different maps can bump shoulders.

Branes offer Marvel a way around that problem. Two universes could be separated along an extra dimension we cannot perceive, then move together through the higher-dimensional bulk.

But, in our science, the collision would not care about New York.

Entire branes would meet. The event could affect every point in the universe, releasing energy throughout spacetime rather than producing one convenient planetary impact zone where the Avengers can assemble.

There’s also no known reason that one person crossing between branes would pull the universes together. Doctor Strange could be obnoxious in another reality for as long as he liked without changing the distance between two universe-sized membranes.

Marvel’s incursions are therefore not brane collisions as we think about them, however theoretically. They are brane collisions rewritten as a cosmic territorial dispute: two realities discover they have been assigned the same space, and existence begins evicting one of them.

That isn’t physics.

But it is probably the closest physics has brought us to Avengers: Doomsday.

Bubble universes gave us separate realities. Many Worlds gave us branching outcomes. Branes gave us universes that can collide.

Marvel took one feature from each, put them together and called the result a multiverse.

Which means it is time to see whether the pieces actually fit.

Marvel’s Multiverse Is a Mash-Up

Let’s take inventory.

Physicists have proposed several ways for there to be more than one “universe.” As Marvel works it, each model provides one piece of the machinery it needs.

The cosmic quilt gives us regions far beyond our observable universe. They could contain other Earths, even other versions of us (thanks infinity!), but only at distances so grotesquely enormous that far, far away becomes a mathematical understatement. No branching. No portals. No incursions.

Eternal inflation gives us bubble universes: separate regions of spacetime that may operate with different physical settings. The bubbles might even collide. But they aren’t alternate histories of our universe, and crossing between them would be less like stepping through a glowing doorway and more like attempting to escape spacetime itself.

Many Worlds gives us branching quantum histories. Every possible outcome remains part of the universal wavefunction (within a bubble). That sounds extremely Loki right up until we remember that decoherence makes macroscopic branches effectively inaccessible to one another. You get all the Lokis. You do not get the TemPad.

Braneworld cosmology gives us entire universes separated by a higher dimension. Those branes might collide, producing something vaguely reminiscent of an incursion. But they would collide everywhere, not just above Manhattan, and America Chavez punching a star-shaped hole between them is not included in the model.

So Marvel went shopping.

It took alternate histories from Many Worlds, independent universes from eternal inflation, inter-universal collisions from brane cosmology and portals from absolutely nowhere in known physics. Then it connected it all with glowing orange circles.

This produces a multiverse that works beautifully as a storytelling machine and terribly as a physical model.

A Marvel “universe” can be a quantum branch, a separate spacetime, a neighboring dimension, or an alternate Earth depending on what the scene requires. The distinctions disappear because the characters can travel among them using the same general set of magic, technology, and unresolved trauma.

That becomes especially important heading into Avengers: Doomsday. If its three universes are quantum branches, they shouldn’t be able to collide. If they are bubble universes, their versions of Earth shouldn’t share corresponding locations. If they are branes, their collision should involve entire spacetimes rather than three groups of superheroes converging on the same battlefield.

Marvel’s multiverse is therefore not one theory.

It is a handful of incompatible theories standing on one another’s shoulders, wearing a cloak and hoping nobody asks to see its equations.

Which, in fairness, has also worked surprisingly well for Doctor Doom.

How Do You Test Somewhere You Can Never Go?

We now have several possible multiverses and no way to visit any of them.

This is inconvenient.

Science does not require us to see something directly. Nobody has visited the core of the Sun, watched the Big Bang, or shaken hands with a quark. We accept their existence because theories predict measurable effects here.

A scientific multiverse needs to leave fingerprints on our universe.

Bubble universes offer one possibility. If another bubble collided with ours early in cosmic history, the impact might have left a circular distortion in the cosmic microwave background—the afterglow of the Big Bang.

Scientists have searched.

They have found unusual patches, including the famous CMB Cold Spot, but nothing that convincingly says, Here is where another universe hit us.

Braneworld models might leave different evidence: gravity behaving unexpectedly at very small scales, energy apparently disappearing into extra dimensions or particles produced by high-energy collisions. Again, no confirmed signal.

Many Worlds is harder. It uses the same quantum equations and generally predicts the same experimental results as other interpretations of quantum mechanics. The disagreement is largely over what those equations mean.

When the double-slit experiment produces interference, Copenhagen-style interpretations say the wavefunction contains several possibilities before measurement. Many Worlds says those possibilities remain within the universal quantum state.

Same dots on the screen. Vastly different account of reality.

Good luck building a science-fair display board for that.

Stephen Hawking and physicist Thomas Hertog attempted to make eternal inflation more scientifically manageable in Hawking’s final cosmology paper. Using a speculative holographic model, they argued that inflation might produce a finite, relatively smooth collection of universes rather than an infinite fractal mess.

The headlines announced that Hawking’s last paper had found a way to detect parallel universes.

It had not.

Hawking and Hertog developed a model, based in part on simplified examples, that might eventually yield more specific predictions about patterns generated during inflation. Those patterns could potentially be tested through the cosmic microwave background or primordial gravitational waves.

That would test the theory producing the multiverse. It would not amount to receiving a transmission from Earth-828.

And this is where the scientific debate becomes uncomfortable.

If a multiverse model explains measurable features of our universe and makes predictions that competing models do not, then its unseen universes may be legitimate scientific inferences. But if every possible observation can be explained by saying, “That’s simply the kind of universe we happen to inhabit,” the multiverse stops predicting reality and starts accommodating it.

Marvel has an easier standard.

It can prove another universe exists by dropping Beast into the post-credits scene.

Physicists have to do it without Kelsey Grammer.

Bad News About the Glowing Door

After all of that, physics is surprisingly generous.

It gives us regions of the cosmos that will forever be beyond our view. Under the right assumptions, some may contain other Earths and other versions of us.

It gives us bubble universes born from inflation, potentially running the laws of physics with different settings.

It gives us quantum histories in which every possible outcome can persist.

It even gives us universe-sized branes that could collide in dimensions we cannot see.

Physics gives Marvel almost everything it needs.

Except the door.

There is no known way to cross the cosmic horizon, escape into another inflationary bubble, step sideways into an Everett branch, or jump from one brane to another. No sling ring. No TemPad. No star-shaped punch through reality.

No wardrobe door hidden at the back of the universe.

That does not mean these other universes are impossible. It means they occupy an uncomfortable region at the edge of science: some emerge naturally from current theories that explain what we can observe, but the universes themselves may remain permanently beyond our reach.

They could be real predictions.

They could be useful interpretations.

They could be mathematical possibilities that nature never actually used.

Or they could be signs that our theories have wandered beyond the territory where evidence can follow.

Thankfully, Marvel does not have to wait for the evidence. It can take distant cosmic regions, bubble universes, branching quantum histories and colliding branes, compress them into one glowing piece of machinery and hand the controls to Doctor Doom.

That’s not how a scientific multiverse works.

But it is how stories work.

Avengers: Doomsday and Secret Wars will almost certainly make the multiverse visible. Universes will acquire borders. Collisions will happen in the sky. Heroes will stand in the ruins of one reality and look across at another.

The real versions—if any of them exist—would be stranger and less accommodating. They may surround us without being reachable, multiply without splitting in any place we could point to, or exist beside us in a direction the human mind was never built to imagine.

Feel small yet?

The multiverse may not contain another Doctor Doom, another Avengers team, or another you.

But the fact that our best attempts to understand reality keep opening the possibility of more reality - more space, more outcomes, more dimensions, more universes…it’s astonishing enough.

Even without the glowing door.

Author’s notes: Portions of this article were adapted and substantially updated from my chapter “Multiverse Theory” in The Science of Rick and Morty (Simon & Schuster, 2019).

A note on the process: I used AI to help me brainstorm, locate research, test explanations, and revise portions of this article. The scientific judgment, argument, source-checking, and final editorial decisions are mine, as is responsibility for anything I got wrong.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This is going to age me a little, but I remember watching “Button, Button” as a segment of the revived Twilight Zone series back in the day—that day being 1986. The segment was adapted from a 1970, 2000-ish word short story by Richard Matheson, first published in Playboy, and later adapted again (much more loosely) into the 2009 movie The Box.

You’ve probably heard the premise by now: a woman receives a box from a stranger. The box itself is unremarkable except for a red button beneath a transparent dome. Push the button, and the stranger will return with $200,000. Oh, and somewhere in the world, someone you don’t know will die.

Simple.

Okay, before we go any further, I need to borrow a warning from John Mulaney. That is, this article won’t work in the “The Science Of…“ way…

Actually, this article will work in the usual The Science Of… way. The problem is that this time, the thing I’ll be treating as a discussion variable is death.

We’re about to walk across some ethically weird ground. I’m going to be completely objective about it and just examine the occurrence of death as a problem to solve.

Yeah, that doesn’t sound right either.

Look, for the next few sections, death is going to become a number. Nobody is being targeted, punished, or judged as more disposable than anyone else. Consider this a short ride aboard the Intrusive Thought Express. I’m your conductor and tour guide.

Oh, and there will be math.

(That wasn’t supposed to be more upsetting than the death stuff.)

Subscribe now

Two Buttons, Two Endings

“Button, Button” was first published in the June 1970 issue of Playboy and has since appeared in collections of Matheson’s stories.

The broad strokes of the two versions are the same. In both versions, the married couple is Arthur and Norma Lewis, and a mysterious package containing the button unit is delivered to their apartment. A note says that a Mr. Steward will visit that evening to explain the device.

He does. Steward explains the terms: $50,000 in the story and $200,000 in the episode, and leaves the couple to decide. Push it: someone you don’t know dies, and they get the money. Arthur and Norma argue over the offer. In the story, Arthur returns the device to Steward, only for Norma to ask for it back. In the episode, Arthur throws it into the trash, and Norma retrieves it. Eventually, she pushes the button.

This is where the two versions split. In Matheson’s original story, Arthur is pushed in front of a subway train on his way home from work. His life insurance payout is exactly $50,000.

As the story goes, the phone rings. It’s Mr. Steward.

It wasn’t her voice shrieking so; it couldn’t be. “You said I wouldn’t know the one that died!”

“My dear lady,” Mr. Steward said, “do you really think you knew your husband?”

Oof. Gut punch.

The New Twilight Zone version ends differently. After Norma pushes the button and Steward delivers the money, he takes the device away and says it will be reprogrammed and offered to someone else. Oh, and Arthur’s fine, aside from a quick flash in his eye that maybe hints he really didn’t know his wife after all.

The “someone” who gets the box next, and Steward directs this to Norma, will be someone whom she does not know. The warning hangs there as the camera closes in on Norma’s horrified face.

Yeah. That lands differently, for so many reasons. My grossest one is that the organization Mr. Steward works for is (given the odds…coming up) basically paying people to kill strangers and get away with it.

Matheson, a veteran of the original Twilight Zone series’ writing staff, wrote the teleplay for the segment. But as television production can go, Matheson’s script was changed, and the different ending tacked on. Matheson disliked the altered ending so much that he had the episode credited to his pseudonym, Logan Swanson.

As I mentioned, I saw the episode a long time ago, and its moral question stuck with me: Would I kill someone I didn’t know, somewhere in the world, for enough money to change my life? I saw it as a teenager, which is prime time for discovering that a question can crawl into your head and live there for the next forty years.

That’s all a credit to the strength of Matheson’s original story, which rightfully belongs beside other creepy-weird stories like “The Monkey’s Paw,” “The Lottery,” “The Veldt,” and “An Occurrence at Owl Creek Bridge” that English teachers give unsuspecting students to read in the 10th grade.

And then smile inwardly as their discussions flare and continue for days.

But as the years went on, I realized something. The central question of “Button, Button” is ethical. There’s no getting around that. But the television ending accidentally creates another question:

What are the odds that a button push takes you out? They you’re the “someone” the person pushing the button does not know?

I mean, as I said up top, I’m treating this objectively and just as a mental experiment, not anything real or that could be real. This is all about probability. Set a few rules, draw a few boundaries, and the Twilight Zone ending starts looking suspiciously like a probability problem.

And…yeah. Matheson had a point. In his original story, “someone you don’t know” becomes a question about whether we ever fully know another person. In the television ending, it feels like a threat: someone else will push the button, and next time the stranger that dies could be you.

And once the threat becomes statistical, I can’t help asking how much of a threat it actually is.

Which makes for a weaker “scare,” to be honest (like when the monsters show up in Backrooms) - define the scary thing with information that can be processed, and it’s not as scary. This is a huge shout-out to learning about what you’re scared of, rather than just being scared of it.

Side note: All walking monsters have knees. Bugs me so much. Bipedal monsters need their knees to walk. As any athlete or person over 40 can tell you, knees are not, generally, the most well-protected or durable pieces of the skeletal system. Why are we wasting time with head shots? My god, just shoot Jason in the knees, then take your time to finish him off while he’s crawling. Problem solved. Knowledge, people. Knowledge. But I digress...

So, assuming nobody has pulled the emergency brake on the Intrusive Thought Express, let’s do the math.

Share

Buttoning Up the Math

From here on, the version of the story I’m looking at is the “Logan Swanson” version that aired on The New Twilight Zone, not Matheson’s original short story. To turn that version’s final threat into a probability problem, we first need to answer one question:

How many people do you know?

For that, I’m going with Dunbar’s number.

Dunbar’s number is the idea that the human brain can keep only about 150 people fully populated in its social universe. Anthropologist Robin Dunbar arrived at that estimate by comparing primate brain size with group size and then applying the pattern to humans. Beyond that circle, people increasingly become acquaintances, strangers, crowds—and, eventually, numbers. People you “don’t know.”

I get it—you may have 10,000 followers on TikTok, but you do not have 10,000 stable relationships. Or, on the flip side, Dunbar did this work before social media let us connect with thousands of people without necessarily knowing many of them well, so 150, while theoretical, may be a little higher than the actual number of stable relationships people have in 2026. Maybe a lot higher.

I’m sticking with 150. Try another number if you like; as you’ll see, it barely matters.

Let’s assume that the box can appear anywhere in the world. We’ll also round the 2026 world population to 8.3 billion.

We’ll call that population N.

Let’s say that Norma₂₀₂₆ is itching to push the button. Norma knows 150 people, and her push kills one randomly selected person outside that circle. If “knows” = 150 people, then the number of Norma₂₀₂₆’s eligible victims is about

N - 151 people.

Why subtract 151 rather than 150? I didn’t check with Mr. Steward, but I’m assuming Norma₂₀₂₆ cannot kill herself by pressing her own button.

Assuming Norma₂₀₂₆ does not know you, your chance of dying from her push is:

1 / (N - 151)

With our rounded population, that is approximately:

1 / 8.3 billion

In other words, if the button-pusher does not know you, your chance of dying from that one push is about 1 in 8.3 billion. As a percentage, that’s

1/8,300,000,000 x 100% = 0.00000000012%

There is one wrinkle to consider. If the next recipient is chosen randomly, that person might know you. If they do, you are not in their pool of possible victims. So your overall probability (P) of dying on a randomly assigned push is:

P(pusher doesn’t know you) x P(you are selected | pusher doesn’t know you)

(N-151/N) × (1/N - 151) = 1/N

(the N-151 terms cancel)

So, if Mr. Steward is telling the truth and both the recipient and victim are selected randomly, the cleanest answer is:

1/N

Your BFF getting the box would make you perfectly safe from that push. But averaged across every possible recipient, it doesn’t change the overall odds. Dunbar’s number helps us define “someone you don’t know,” but ultimately it cancels out of the equation.

Keep selecting randomly and pushing the button indefinitely, and the probability that it eventually kills you approaches 100%. The expected wait is 8.3 billion pushes. That does not mean the box is guaranteed to kill you by push 8.3 billion. At that point, your chance of having died is about 63%.

After about 5.75 billion pushes, the box is more likely than not to have killed you. After 8.3 billion, the probability is about 63%. But there is no deadline. Probability does not make appointments.

That assumes the population stays fixed at 8.3 billion, which it won’t.

The United Nations projects the population to peak around 10.3 billion in the mid-2080s before declining slightly by 2100. Okay, that’s not exactly a smidge, but close enough that our conclusion survives.

Subscribe now

Give It to Me Straight: How Long Until the Box Gets Me?

Let’s turn pushes into time. If the box is pushed once per day. The expected waiting time would be:

8.3 billion days ÷ 365 ≈ 22.7 million years

The point at which the box has a 50% chance of having killed you comes earlier, at about 5.75 billion pushes:

5.75 billion days ÷ 365 ≈ 15.8 million years

Those are not contradictory answers. At 15.8 million years, your cumulative risk reaches 50%. The 22.7-million-year figure is the average wait across an enormous number of hypothetical runs.

Let’s put some hustle on Mr. Steward. What if the button is pushed once per hour?

8.3 billion hours ÷ 24 ÷ 365 ≈ 947,000 years

What if someone pushes it once per minute?

8.3 billion minutes ÷ 60 ÷ 24 ÷ 365 ≈ 15,800 years

So, if the box moves at anything resembling a human pace, you take the money and spend the rest of your life facing a real (but extremely small) risk.

And Dunbar’s number still barely matters. Excluding 150 people from a pool of 8.3 billion is almost nothing—and when the recipient is also chosen randomly, the Dunbar term cancels out altogether. The horror isn’t that the odds are high. The horror is that the box turns everyone outside your circle into statistical fog.

Matheson’s original trap is moral. The television version makes it look actuarial.

What Are My Odds During a Normal Lifetime?

The huge numbers above are average waiting times, not how long you will live.

So let’s make it personal. Suppose you have 50 years left, and the box keeps moving.

Frequency matters.

One in 8.3 billion? That’s impossible. Sure...but what if you repeat the experiment 26 million times?

Fortunately for us, Mr. Steward probably can’t explain, deliver, collect, and redistribute the box 1,440 times every day for fifty straight years.

Or can he?

Yeah, But Compared To…?

The numbers are interesting, and I think the last of the ghosts in my head have finally been satisfied.

But, after all of this, it settled in on me that the numbers aren’t really the point.

Assuming the box changes hands once per day, your chance of dying from it over the next 50 years is roughly 1 in 455,000.

That’s tiny. You take bigger risks before lunch. Seriously.

Your lifetime odds of dying in a motor vehicle crash are around 1 in 100. Your odds of dying in a fall are about 1 in 250. Even being struck by lightning at some point in your life is more likely than being killed by the box (1 in 15,000).

Putting real numbers on the television ending does something unexpected: it almost completely defangs the curse. If you push the button, and the box moves on, statistics say you should probably spend zero hours and zero minutes worrying about dying from “someone you don’t know” pushing the button.

Mr. Steward’s final warning isn’t nearly as terrifying once you see the odds. Compared with the risks we live with every day, the box barely registers. Which leaves us with a very uncomfortable answer:

Statistically, you should push the button.

If your only goal is maximizing your own outcome, it’s an incredible deal. You get the money, and the odds that you’ll ever pay the price yourself are vanishingly small.

So why does it still feel wrong?

Because the button changes something more important than the odds, it changes who makes the choice, and who lives with the consequences.

Most of the risks we take in life primarily expose us. We drive. We board airplanes. We take medications with known side effects. We travel over bridges knowing that no bridge design is perfectly risk-free. Doctors recommend surgeries whose benefits must be weighed against possible harm. Modern life depends on countless decisions that carry small statistical risks because a world with zero risk does not exist.

Sometimes we accept those risks for ourselves. Sometimes our choices broadcast a little risk outward—to neighbors, workers, passengers, customers, or strangers on the other side of the world.

Most of the time, we experience the benefits while the risks are spread thinly across thousands or millions of strangers. Those risks are real, but they are distant. Usually invisible. We need electricity for modern life. No way of producing it comes with clean hands and zero risk. The same is true of mining the materials used in our phones, computers, batteries, and other devices, as well as countless other industries that enable us to live a modern lifestyle in a wealthy country.

The button refuses to let the stranger stay invisible. It doesn’t merely tell you that harm is possible. It tells you that someone will die, and that your decision caused it. That’s why the ending lingers.

The math says you will almost certainly never pay the price yourself. The story asks whether you can live with knowing someone else did.

Statistics are very good at telling us how often something happens.

They are completely silent about whether it should.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four. This piece was heavily updated to reflect the X-Men ‘97 connection, as well as updated science.

X-Men ’97 on Disney+ is far better than any revival of a 30-year-old Saturday morning cartoon has a right to be. Yeah, I said it.

Season 1 was amazing, and Episode 5, “Remember It,” has made me tear up on multiple rewatchings. It just…man. It hits as hard as, or harder than, anything in the X-Men movies. Now that Season 2 is out, it plays all the right nostalgic notes and features two of my favorite X-Men from… well, forever: Nightcrawler and Beast. And Apocalypse is the main villain (so far).

Awesome.

While they’re three of my favorite characters, they all have something else in common: they’re blue (or blue-ish gray in the case of Apocalypse).

Blue has been a go-to character color for the X-Men and other comics, to be fair, for years. A quick and wildly incomplete rundown of blue mutants gives us Beast, Nightcrawler, Archangel, Mystique, and En Sabah Nur (Apocalypse). And that’s not counting Yondu, Nebula, the blue-skinned Kree or the pure-blood Atlanteans—Marvel’s, not DC’s. Add in all of Marvel’s alternate Earths, and we’re going to need a bigger list.

There’s a lot of blue being splashed around the Marvel Universe, and its mutants have gotten more than their share. Now, I get it. Blue is visual shorthand for someone who is immediately and unmistakably different. You can’t hide Nightcrawler in a crowd.

But this is The Science Of…, not The Sociology Of… So let’s talk about blue mutants.

Because humans don’t come in blue.

Subscribe now

A few years back at The Science Of’s “Superhero Science: Ask Us Anything!” panel at AwesomeCon, Duke University biology professor Dr. Eric Spana rolled his eyes at the idea of a mutation producing a blue-skinned human.

Spana later confessed that declaring blue mutants completely impossible was a little too broad: blue humans might be possible. But a mutation producing a healthy, fully functional, superheroing blue human? That’s where things get…troublesome.

“We can sum up color into two broad categories: structural color and pigment color,” Spana says.

“Pigment color is what makes your jeans, pen ink, and stained-glass blue. Structural color is a physical effect of light absorption and reflection where only the blue light is reflected and seen by your eyes. There are only a few organisms on Earth that can make a blue pigment - a few butterfly species, for example.”

A few animals can produce genuine blue pigments, but among vertebrates, that ability is spectacularly rare. Almost every blue bird, fish, reptile or mammal you’ve seen is using microscopic structure to make blue—not blue pigment.

Vertebrate, here meaning animals with backbones. Genuine blue pigment is spectacularly rare among vertebrates. Humans aren’t one of the exceptions.

For humans, vertebrate and proud…well, we didn’t get the blue-pigment package.

We can’t make our own blue pigment. Don’t got the genes. Period.

People can’t be blue.

But there are blue people.

*No, Seriously, Blue People

There have been cases of people born blue. Not Paul Karason blue. His skin turned blue-gray after years of consuming homemade colloidal silver, which caused a permanent condition called argyria. Different road to blue. Still, admittedly, very blue.

In an X-Men-ish connection, some people born blue owe the color to an inherited mutation. It does not, unfortunately, come with superpowers.

The most famous blue-skinned family in American history was the Fugate family of eastern Kentucky, whose story stretches from the early 1800s into the 20th century. Several family members had methemoglobinemia, a condition that can be acquired through exposure to certain drugs or chemicals—or inherited, as it was in the Fugate family.

Thinking back to biology, an autosomal recessive condition generally appears when someone inherits two altered copies of the same gene—one from each biological parent. The Fugates lived in a relatively isolated region where the local gene pool was small, and marriages sometimes occurred between relatives, including distant cousins. Over generations, that made it more likely that two people carrying the same rare genetic variant would have children together.

If both parents carry one altered copy, each child has a 25% chance of inheriting two altered copies and having the condition. There’s also a 50% chance the child will be an unaffected carrier and a 25% chance the child will inherit neither altered copy.

Every pregnancy rolls the genetic dice again.

And no, the parents don’t have to be closely related for this to happen.

Share

Genes in a region can disperse through a population over generations to the point that two completely unrelated individuals could be carriers of the recessive form and not know it. A rare genetic variant can circulate through a population for generations, allowing two people who aren’t closely related to carry it without knowing.

Normally, less than about 1% of the hemoglobin in your blood is methemoglobin. In methemoglobin, the iron has been oxidized into a form that can’t bind oxygen. As that percentage rises into the 10–20% range, the skin can begin to look blue. Too much methemoglobin reduces the blood’s ability to carry and release oxygen. One visible result can be cyanosis—a blue or purple tint to the skin, lips and nail beds.

Cold can turn your lips and fingertips blue too, but it takes a different route. Blood vessels near the surface constrict to conserve heat, reducing circulation through those tissues and making deoxygenated blood more visible. That can produce cyanosis, but it isn’t the same blood chemistry found in methemoglobinemia.

Normally, an enzyme converts methemoglobin back into working hemoglobin. The enzyme was once commonly called diaphorase; today, it’s more precisely known as cytochrome b5 reductase. The inherited form associated with the Fugates reduced the activity of that enzyme, allowing methemoglobin to accumulate.

“In severe cases of this condition, altered oxygen binding to that form of hemoglobin causes lowered oxygen availability and cyanosis, which is a bluish skin trait,” Spana explains. “This seems unlikely for X-Men as the low oxygen causes substantial health problems, not superhero traits.”

As Spana hints, there is an important exception. In type I congenital methemoglobinemia, the enzyme deficiency is largely limited to red blood cells. A person may look dramatically blue while remaining otherwise relatively healthy. Some people with the type I form have lived long lives with few effects beyond the startling color of their skin. Family accounts described Luna Fugate as especially blue, yet she reportedly lived a long life and had 13 children.

Congenital methemoglobinemia remains rare. Among the Fugates’ descendants, affected children became less common as families moved away and the population became less isolated. Carriers were simply less likely to have children with someone carrying the same rare variant.

So yes—blue people do exist, and some people with the inherited type I condition can be remarkably healthy. But congenital methemoglobinemia is rare. That alone makes it a poor explanation for Marvel’s blue population. Beast, Nightcrawler and Apocalypse aren’t merely surviving with reduced oxygen delivery; they’re performing acrobatics, teleporting through combat and conquering timelines.

These are not people whose blood is struggling to deliver oxygen.

But just to be clear: people with methemoglobinemia aren’t blue because their skin contains a blue pigment.

No blue pigment. Just altered blood chemistry showing through the skin.

The True Blue Bloods of the Animal Kingdom

“Horseshoe crabs offer one possible explanation for blue mutants—but it doesn’t work,” Spana says. “The blue blood is caused by a copper-containing protein called hemocyanin that they use to carry oxygen in their hemolymph, which is the crab version of blood. Hemocyanin is found in many mollusks and arthropods, but humans don’t use anything like it to transport oxygen. Humans don’t have the genes or physiological machinery for a hemocyanin-based circulatory system. The Kree, on the other hand? Maybe that’s exactly what’s going on with their blue skin and blue blood?”

Side note: Horseshoe crabs aren’t crabs. Because biology enjoys making names as unhelpful as possible. And just to be 100% clear, oxygenated hemocyanin is blue. Actually blue. No cyanosis, no optical trick, and no disappointing lack of pigment.

Blue blood.

That last bit is where Spana’s scientific mind has to draw a line between real-world genetics and comic-book genetics. Mutations can alter, delete, duplicate, and rearrange DNA. What they don’t generally do is install an entirely new biological system—fully assembled, properly regulated and ready for superhero duty.

Subscribe now

If X-Men ’97 suddenly announced that Nightcrawler has hemocyanin instead of hemoglobin, X-Men-loving biologists everywhere would feel a small but measurable part of themselves die. A spontaneous mutation couldn’t simply replace hemoglobin with hemocyanin. It would have to rebuild oxygen transport, copper regulation, blood chemistry, and probably several other systems we haven’t even thought of yet.

And then Marvel would have to do it again. And again. And again.

It’s the same problem that turns scientists into the bad guys at every superhero-science panel:

“How can that character have wings?”

“They can’t.”

Boooo, science.

No one likes to hear “They can’t,” but really—Warren Worthington III sprouted two enormous, fully feathered, functional wings from his back.

No one likes to hear, “They can’t,” but really - Warren Worthington III sprouting lovely, angelic feathered wings out of his back? Try tracking everything that would have to change: skeleton, muscles, nerves, circulation, skin, feather growth, balance, and the brain circuitry needed to control two entirely new limbs. That isn’t one mutation. That’s a full-body renovation.

Evolution can produce new structures by duplicating, modifying and repurposing existing ones—but it does that through accumulated changes across populations and generations. It does not hand one teenager a finished set of wings.

None of this is meant to rain on the X-parade. Not at all. The X-Men are cool. They were cool before I knew what a genome was, and they’ll remain cool regardless of what biology says. But if the X-Men get you interested in mutation and genetics, they’re the springboard—not the final answer. Follow that question into real genetics, and things get every bit as strange as the comics. Trust me, plenty of working biologists know exactly who the X-Men are—and some of them can identify an obscure mutant faster than they can identify a colleague. For some of them, asking why the X-Men couldn’t exist was the first step toward learning what actually could.

Oh, and Hank McCoy? He gets an asterisk. Beast was already a mutant, but his blue, furry form came after he injected himself with a serum of his own design and triggered another transformation. He can star in his own title, GMO-Men. And as we’ll see, Beast may be the one blue mutant biology can almost explain.

“But wait,” you say. “What about all the blue animals?”

Mystique…just…wait. Blue skin, blue...scales on her skin, too? (Image: Disney)

What About the Actual, For Real Blue Animals, Then?

“What about that bird?”

“That mandrill’s face and butt?”

“That shrimp?”

“That bug?”

“That monkey’s scrotum?”

“My blue eyes?”

If blue pigment is so rare, why are there so many blue animals?

Because most of them aren’t using blue pigment.

They’re using physics.

“In many blue animals, microscopic structures interact with white light so that blue wavelengths are reflected or scattered back toward our eyes,” Spana says. “The color comes from the physical arrangement of the material, not from a blue pigment. In blue morpho butterflies, nanoscale structures in the chitinous wing scales reflect an intense blue.”

Change the spacing of those structures, and you change the color they produce. Same material. Different architecture. Different light.

“Blue jays and peacocks also use nanoscale structures in their feathers, built from keratin, air and, in some cases, melanin, to control which wavelengths reach your eyes,” Spana continues. “And in some mammals—including mandrills—carefully organized collagen fibers in the skin produce blue structural color.”

Wait…collagen? We have collagen…

Nightcrawler is back in the game.

Your blue eyes pull off a similar trick. There’s no blue pigment in a blue iris. In a blue iris, microscopic structures in the stroma (the front portion of the iris) scatter shorter wavelengths of light back toward you more strongly than longer wavelengths. You see that scattered light as blue. The butterflies, feathers, and mandrills use different microscopic arrangements, but the larger trick is the same: structure controls light.

Blue eyes contain less melanin in the front layers of the iris than brown eyes. With less pigment available to absorb incoming light, shorter blue wavelengths are scattered back toward the viewer while more of the longer wavelengths pass deeper into the eye and are absorbed.

The eye contains no blue “dye.” It just sends more blue light back at you.

The sky, skim milk, and bluish exhaust all pull related versions of the same stunt. Different materials. Different-sized structures. Same basic result: more blue light reaches your eyes.

And because that blue is produced by reflected and scattered light, its intensity changes with the lighting. Someone with striking, almost glowing blue eyes won’t look equally blue under every set of lights.

Those almost-glowing blue eyes? Part biology, part lighting department.

For the X-Men, two of those mechanisms give us something to work with,” Spana says. “Humans don’t produce chitin, so the blue-morpho route is out.”

Sorry Mystique, no butterfly upgrade.

“Hair and feathers aren’t chemically identical, but they are both protein-built structures,” Spana says. “That at least gives Beast’s fur something biology can work with. Beast might have one set of changes producing dense fur and another organizing that fur at the microscopic level so that it reflects blue light.”

Two enormous biological asks instead of one impossible blue pigment. Progress!

Nightcrawler isn’t walking around in a full-body blue-jay coat. His problem appears to be skin.

“His mutation might be one like the ordered collagen fibers seen on the noses and backsides of mandrills and give him blue skin all over,” Spana says.

That’s a very large “if,” but it’s a real biological road to blue skin.

The mandrill comparison doesn’t make Nightcrawler easy to explain, but it keeps the door to blue mutants cracked open. Mandrills are primates, and humans already make the same basic structural material: collagen. But reorganizing that collagen across someone’s entire skin so that it consistently reflects blue light?

That’s a tough sell.

Could gene editing eventually get us closer? Maybe—but CRISPR isn’t a magic wand. It can target particular DNA sequences, but we would first need to know which changes create blue structural skin and then deliver those edits safely to the correct cells.

An easier sell? CRISPR - the technology that allows scientists (or largely, anyone) to insert genes at specific locations in DNA.

“Oh, that would be killer,” Spana says. “If the molecular change in human vs mandrill collagen fibers were easy, you could make genetic tattoos via specific application of CRISPR to skin regions! That would make the blue structural rather than pigment-based.”

To be clear, this is the part where we have sprinted past “current medical technology” and planted a flag in “extremely cool future possibility.” Scientists are working on gene editing in skin, but making a patch of human tissue grow a precise, light-reflecting collagen nanostructure is a whole different level of difficulty.

CRISPR can edit DNA. It cannot currently give you a Nightcrawler sleeve.

Your local tattoo artist would be a better bet. But again, that’s the insertion of pigment under your skin to make it look blue.

Marvel makes its mutants blue with ink and pixels. Biology would have to do it with structure.

No blue pigment required.

Beast? Keratin.

Nightcrawler: Collagen.

Apocalypse? Comics.

But still — no blue pigment. Only structure.

More:

How Animals Hacked the Rainbow and Got Stumped on Blue

How Nature Uses Physics to Make Blue Without Pigment

Why is the Color Blue Difficult to Find in Nature?

Why Are Some Feathers Blue?

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

Okay—so in The Flash #34…well, a bunch of stuff goes on. The “battle” between Flash and Gorilla Grodd and his army is set up as a flowchart through time, and it’s one of the more innovative uses of the medium I’ve seen in a while.

But…

Toward the end of the issue, Flash discovers that Central City is covered in what he initially thinks is fog. Then he realizes it’s steam.

Said steam was generated when one of the Flash’s Rogues, Heat Wave, used six giant heat generators to vaporize a chunk of the river. Apparently, he does this to expose a shipwreck with treasure on it? I’m looking forward to reading issue #35, which shows the creative team is doing its job.

Depending on which map of the DC Universe you’re looking at, Central City is in Missouri, across the Missouri River from Keystone City. Look, there are reasons and explanations for all of this, including why in the world there are two fairly large cities right next to each other in the DC Universe, and I could tell you all about it. Seriously. I could bore you (and me) to tears.

But I’d rather not.

What I want to talk about is what Heat Wave is doing, because it resembles a problem I give my students during our thermochemistry unit in chemistry—and again when physics students hit thermodynamics and heat transfer.

In short…

That’s a really cool scene there with Heath Wave vaporizing the river you got there.

It would be a shame if someone did some real-world science to it…

Okay, okay—DISCLAIMER—we’re not doing this to yuck anyone’s yum or rain on any parades. The DC Universe is fictional. Our rules don’t apply, or there are workarounds. (See: the Speed Force.) My curiosity kicked in when I saw the scene and started wondering what it would look like in our world, with our physics.

And my electric bill.

You wanna do some physics?

Come on. I’ll make it easy.

(Oh, and in case you’re curious, I’d give about an hour of class time for this in a course…)

Step One: How Much Water is That?

This is the only step where we need to make some approximations. We need to determine the volume of water Heat Wave has already vaporized, based on what we see in the panel. Let’s use the bridge as our ruler and call the river about 150 meters wide. The affected stretch looks roughly 800 meters long (about half a mile), and based on the buildings, bridge, cars, streets, and everything else we can use for scale, let’s call the river about 8 meters deep.

All numbers are open to interpretation. If you don’t agree with them, put your own numbers in and join us for Step Two.

As pictured, Heat Wave has vaporized a shoebox-shaped volume of water. The formula for volume has been the same since you were in school:

Volume = width × length × height

Volume = (150 m)(800 m)(8 m)

Volume = 960,000 m³ of water.

To make the calculations easier, let’s nudge that up to 1 million cubic meters of water. What’s the mass of that much water? Well, the mass of 1 m³ of water is 1,000 kg, so:

1 x 10⁶ m³ × 1000 kg/m³ = 1 × 10⁹ kg

That’s 1 billion kg of water.

That’s a lot of water.

Step Two: Vaporize!

Cool your jets for a second. We can’t vaporize water in one step. To turn water into water vapor, you have to go through two steps. First, the water temperature must be raised to its boiling point, 100 °C at normal atmospheric pressure. Then it can be vaporized. Each step requires dumping energy into the water, hence Heat Wave’s six giant heat blasters on the shore.

Why do things work this way?

Heating transfers energy into the water, making its molecules move faster (and taking up more space). As the water’s temperature increases, its molecules move faster and faster until the water reaches 100 °C. Once there, the water still needs more energy, this time to overcome the attractions between water molecules and escape as a gas.

Figuring out how much energy Heat Wave needs requires two calculations, so we need two formulas.

The first looks like this: Q = mcΔT

That means the energy needed (Q) to raise the temperature of a certain mass of water equals the water’s mass (m), multiplied by its specific heat (4,186 J/kg·°C), multiplied by the change in temperature (ΔT).

That specific heat means it takes 4,186 joules of energy to raise the temperature of one kilogram of water by 1 °C. And ΔT is just the final temperature minus the initial temperature.

Let’s assume that the water in the river is 20 ^oC (about 68 ^oF). We need to raise that water to its boiling point of 100 °C, so ΔT is 100 − 20 = 80 °C. The rest of our math looks like this:

Q = (1 x 10⁹ kg)(4186 J/kg^oC)(80)

Q = 3.35 x 10¹⁴ joules

As I remind my students, that’s just to heat the water to the boiling point. Now, we’ve got to vaporize it. New formula:

Q = H_vm

(Note - H_v is sometimes called the “latent heat of vaporization and abbreviated as L_v)

This means the energy (Q) required to vaporize a given mass of water (m) equals the heat of vaporization of water (2.26 × 10⁶ J/kg) multiplied by the mass of the water.

Why is the heat of vaporization number so much bigger than the specific heat of water?

Think about what you need the water molecules to do. Before, you were adding energy to make them move faster. Now, you’re asking them to break away from their pals and fly off into the atmosphere, overcoming the attractions between them and pushing back the surrounding atmosphere.

That’s a much bigger ask. In Heat Wave’s case:

Q = (2.26 × 10⁶ J/kg)(1 × 10⁹ kg)

Q = 2.26 × 10¹⁵ joules

Side note: There’s no value for temperature in this equation because there’s no temperature change. While a substance is vaporizing, the energy being dumped into it is used to overcome the attractions between its particles and separate them from one another. Heat’s still going in, but the temperature isn’t changing. It’s one of the things my students struggle with, too.

So how much energy does Heat Wave need in total to heat up and vaporize 1 billion kg of water? We add the two numbers together.

Q_total = 3.35 × 10¹⁴ + 2.26 × 10¹⁵ = 2.6 × 10¹⁵ Joules

Or 2.6 petajoules.

That’s a lot of energy, but I know. That number means absolutely nothing to you.

Subscribe now

Step Three: TNT!

When talking about energy, joules aren’t that helpful. We don’t run into them often. We could convert everything to calories and get another interesting number, but it still wouldn’t mean much. So let’s use something we’re all much better at understanding: explosions. Specifically, trinitrotoluene, better known as TNT.

1 kiloton (1,000 tons) of TNT releases the energy equivalent of 4.184 × 10¹² J when it explodes.

So, for our vaporized river…

(2.6 × 10¹⁵ J) ÷ (4.184 × 10¹² J/kiloton) = 620 kilotons of TNT

Just for comparison…

Hiroshima atomic bomb: about 15 kilotons of TNT

Nagasaki: 21 kilotons

Essentially, to vaporize 1 billion kg of water, Heat Wave has to dump the energy equivalent of about 40 Hiroshima bombs into the river.

Step Four: Electricity!

A simple idea as we go through this: energy is energy. It can take different forms, but it’s always energy.

It can’t be created or destroyed, only changed from one form into another. Some of that energy usually becomes less useful to us, often because it ends up dispersed as heat, but that’s another law of thermodynamics and not quite what we’re on about here. At least not yet.

I won’t go into the full conversion here, but joules can be converted to kilowatt-hours, the unit of energy we pay for on our electric bills each month.

It goes like this:

1 kWh = 3.6 × 10⁶ joules

So let’s convert the energy Heat Wave needs into kilowatt-hours.

2.6 × 10¹⁵ joules ÷ 3.6 × 10⁶ joules/kWh = 720 million kWh

or

720 gigawatt-hours.

That’s still a ridiculous number, but this one comes with a price tag.

Let’s say Heat Wave’s heat generators are plugged into the power grid. Not a great idea, but go with me here. As I mentioned earlier, kilowatt-hours are the unit we use to measure the electrical energy we buy from the power company. Think of them like gallons of gasoline. You pay for gas per gallon; you pay for electricity per kilowatt-hour used.

Heat Wave uses 720 million kilowatt-hours of electricity to vaporize a billion kilograms of river water.

Okay…

Let’s try this with a nice, round industrial electricity rate of $0.10 per kilowatt-hour. Hey, maybe Heat Wave knows someone at the power company and can get a good deal…

720,000,000 kilowatt-hours × $0.10/kWh = $72 million.

Okay, maybe he just plugged his heat rays into some nearby houses with extension cords. Residential electric rates are a little higher than industrial rates, because of course they are, so let’s say $0.18/kWh.

720,000,000 kilowatt-hours × $0.18/kWh = $130 million.

This assumes the heat rays are 100% efficient, that is, every joule of electricity is converted into heat in the river.

That’s not happening.

Some of that energy will heat the generators, the air, the riverbed, and pretty much everything else nearby, so the prices above are lowballing it. If Heat Wave is paying for electricity, his actual bill could easily run into the hundreds of millions of dollars.

In the final panel of the issue, Heat Wave is standing on the deck of what looks like a recovered ship, his foot resting on a chest full of—I guess?—treasure. It’s going to take a lot of treasure to achieve any reasonable ROI.

Okay, okay — he’s most likely not plugging the heat rays into the city’s power grid. Presumably, they have their own power source. Nuclear power is at the top of that list. Yeah, if we go down this road, Heat Wave brought six extremely unlicensed nuclear power systems into Central City and turned the dials to 11.

But wait — there’s more! How fast did Heat Wave do this?

Share

Step Five: Power!

Power is the rate of change of energy per unit time. Energy tells us how much. Power tells us how fast.

The formula for power looks like this:

Power = energy ÷ time

When energy is measured in joules and time in seconds, the answer comes out in watts.

I know we were talking about kilowatt-hours above, but now we’re asking a different question. Before, we wanted to know how much energy Heat Wave needed. Now we want to know how quickly he delivered it. The same amount of energy delivered over an hour and delivered in 30 seconds is still the same amount of energy. But the second one requires vastly more power.

Let’s say it took Heat Wave 30 seconds to vaporize one billion kilograms of river water. I’m guessing here, but the comic certainly doesn’t make it look like he spent the afternoon doing this.

That would look like this:

Power = 2.6 × 10¹⁵ joules ÷ 30 seconds

Power = 8.7 × 10¹³ watts

or

87 terawatts.

I know. We’ve got another ridiculous number that means almost nothing on its own. Let’s put it into context. In 2025, the entire world used 31,779 terawatt-hours of electricity. Spread across the year, that means the entire world was using electricity at an average rate of about 3.63 terawatts at any given moment.

Heat Wave’s generators would need to produce 87 terawatts—about 24 times the average electrical power being used by the entire world.

For 30 seconds.

And that’s just to clear the river once. Even in comics, rivers keep flowing.

That treasure really better be worth it.

Step Six: Rivers Are Gonna…River?

The first billion kilograms of water was just the cover charge.

Once the riverbed is exposed, Heat Wave has to keep paying. He has to keep vaporizing water.

I’m going to try and keep this short, but Heat Wave needs to do three things:

1. Vaporize ‘a section’ of the river — which has already required a lot of energy.

2. Hold back vertical walls of water without a dam. And I don’t see Moses.

3. Continuously vaporize new water flowing in from upstream

We’ve handled #1; let’s skip #2 for a second and deal with #3.

I’m not budging on this one — he has to be continuously vaporizing the water; otherwise, it would pile up and flood the downtown (and flow around the wall, filling the exposed area again).

So while we’re working out an energy budget, let’s add what it would take to keep vaporizing water as it flows into the exposed riverbed.

A ballpark flow rate for a large river — let’s go with about 1,000 m³ of water per second.

Each cubic meter of water has a mass of 1,000 kg, so:

1000 m³/second × 1,000 kg/m³ = 1,000,000 kg/s

That’s one million kilograms of water per second that needs to be vaporized to keep the exposed area water-free.

To vaporize incoming water continuously, Heat Wave would need:

1,000,000 kg/s × 2.6 × 10⁶ J/kg = 2.6 × 10¹² joules/second

Since J/s = watts, that’s 2.6 terawatts.

So even after the initial blast, Heat Wave needs roughly 2.6 TW of continuous power to keep the river from refilling. That’s about 70% of the entire world’s average electrical power consumption in 2025.

And again, that still doesn’t explain #2 — the water walls.

Maybe he’s vaporizing the water right where it flows into the exposed area, creating the appearance of a vertical wall of water? But that surface would look like the top of a violently boiling pot, not a clean wall of water.

In the panel, the river appears to stop at the edges of the exposed riverbed, standing there like it got a polite note from management.

That is not how liquids behave.

But given that this is how the water is behaving—and given that Flash is standing inside the water wall (above) without being boiled alive—I’m willing to budge on #2 and let the wall go. It’s some kind of force-field magic.

But the other stuff? Where there’s steam, there’s heat. Heat Wave says it’s heat. So the missing billion kilograms of water? That was vaporized.

And somehow the upstream flow of the river is being stopped, so continuous vaporization isn’t off the table entirely.

Subscribe now

A Quick Weather Forecast…

So far, this has all been about energy. The thing is, energy—and water—in the atmosphere are what drive weather.

You can probably see where this is going.

Again, with the caveat: “If this took place in our universe…”

Let’s run the meteorological numbers:

1. One billion kilograms of water is on the order of the amount of water contained in a large thunderstorm. Heat Wave effectively put an entire thunderstorm’s worth of water into the atmosphere over Central City instantly.

2. The air around the river would become extremely warm and saturated with water vapor. That heat and humidity are extremely dangerous to anyone exposed to them (see my pal Joe Hanson explain it over here), but let’s worry about the weather. As shown in the art, dense clouds will form almost immediately.
   
   (Technically, the white stuff we can see isn’t water vapor. Water vapor is invisible. Those clouds are tiny liquid water droplets that have already condensed.)
   
   But that enormous mass of hot, moist air isn’t going to politely hug the ground and turn Central City into Jack the Ripper’s foggy London.

3. Turning liquid water into vapor takes in heat, but turning vapor back into liquid water releases heat. How much heat? Well, it took 2.26 petajoules to change that boiling water into vapor, so up to 2.26 petajoules of latent heat can be released as that vapor condenses.
   
   That is an enormous amount of energy being released into the atmosphere, and it would drive powerful convection. So yeah—given a reasonably unstable atmosphere, Heat Wave may have just whipped up a massive thunderstorm from scratch, which means he’s stomping all over the territory of this fellow Rogue:

But we’re not done with this just yet.

4. The enormous mass of hot, moist air would be highly buoyant and rise rapidly. In weather-ese, those are called updrafts. Any planes trying to fly through that rapidly developing convection would have a very bad day. How high would it go? That depends on the atmosphere over Central City that day. But a powerful thunderstorm can reach the upper troposphere and, in extreme cases, push against or even briefly overshoot the tropopause.
   
   Yeah. We’re cooking up some sweet weather now.

5. As the rising air cools and water vapor condenses, clouds form, and precipitation begins. Given the sheer amount of water available, the rainfall could be easily described as torrential. If the storm develops strong enough updrafts to carry water above the freezing level and keep hailstones aloft, hail becomes possible, too.
   
   Heat Wave put a chunk of the river’s water into the atmosphere. Now some of it is coming back down on Central City.

6. And then, quite possibly, the lightning. Oh, there could be a lot of lightning.

7. And shockwaves. All of that newly heated water vapor and hot air has to go somewhere, and initially, it would push the surrounding atmosphere out of its way. As that enormous mass of hot, moist air rises, surrounding air would flow in underneath it to replace it. Later, rain-cooled air could come crashing back down as powerful downdrafts, spreading outward when it hits the ground as a gust front. So now we’ve potentially got torrential rain, strong winds, lightning, and maybe hail.
   
   Heat Wave wanted to empty a river. He made weather.

But…In the End…

Of course, we don’t see any of this happen.

We don’t see the massive thunderstorm. We don’t see the river immediately trying to refill itself. We don’t see Central City dealing with 2.6 petajoules of heat dumped into a billion kilograms of water.

And Flash is standing inside a vertical wall of water that should be boiling, so clearly, something else is going on here.

Which is fine.

The Flash operates under a different set of physics. We’ve known that for a long time. There’s the Speed Force, after all. Maybe Heat Wave has found the Heat Force (Heat Force, © Matt Brady, 2026, in case he hasn’t). I don’t know. I don’t make the rules.

And really, I think our boy Captain Carrot said it best:

One final disclaimer: Since the relaunch of The Science Of… here on Substack, I’ve written a lot about Ryan North’s comics. I would like to take this opportunity to state for the record that I am not stalking Ryan North (that he knows about), nor am I Ryan’s secret child (I’m older than him), nor is he my son (he’s Canadian—not that there’s anything wrong with that - little jelly about that these days, actually).

I love the big science ideas or tidbits Ryan always puts in his stories.

They make me feel like a kid reading comics again—I’m excited, curious, and wondering about the story and ideas. It’s a good thing.

Ryan, this should make your lawyers happy, right?

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four.

Let’s talk about the Gorn.

First introduced in the 1967 Star Trek (TOS) episode “Arena,” the Gorn morphed from a guy in an off-the-rack monster suit into a Xenomorph/Predator-esque threat with their own spin.

Now, 56 years later, they’re a chilling threat to the Federation in Star Trek: Strange New Worlds. They first made themselves known in season 1, and … yeah, that season 2 cliffhanger.

And holy crap, they’re tough. And scary.

To help dig into the science of the Gorn, I sought some help from Dr. Mohammed Noor, a biology professor at Duke University and author of Live Long and Evolve: What Star Trek Can Teach Us About Evolution, Genetics, and Life on Other Worlds, and, as he calls it, an “occasional Star Trek science consultant.”

Noor’s YouTube channel, BioTrekkie Explains, features Noor as well as his semi-regular guest, actor (and Duke almuna) Jayne Brook, who played Admiral Katrina Cornwell on Star Trek: Discovery. Together, they dig into the life science of all the Treks. An aside to biology students and STEM teachers: it’s a great review of major concepts in the life sciences.

Before we get into the possibilities and plausibilities, from the start, this is chiefly about the modern Strange New Worlds Gorn. They’ve shown up in many places throughout Star Trek canon, with each iteration a little bit off from what was seen before.

That said, a quick rundown of modern-day Gorn would be useful. What we know about the Gorn so far:

• They are quadrupedal reptiles early in life and apparently become bipedal as adults.

• They are reportedly cold-blooded, slowed, and/or killed by extremely low temperatures.

• They have at least two distinct life stages - hatchling/juvenile and adult. Both have tails.

• They are social, interacting in social groups towards a common goal or outcome. Their larger governmental organization is the Gorn Hegemony, located in the Beta Quadrant of the galaxy.

• They implant parasitic eggs in other warm-blooded life forms.

• They are cunning hunters, often using bait to lure other prey.

• They hunt humanoids, deposit eggs in them, and relocate them to “breeder worlds,” where the eggs hatch from the humanoids. Some humanoids are hunted for “sport.”

• Hatchlings can implant eggs in hosts, apparently without first mating.

• The eggs — or whatever reproductive stage eventually becomes an egg — are transmitted in the Gorn’s saliva or venom. Get sprayed, and you’re a baby factory.

• The hatched offspring compete, killing one another until only the strongest Gorn survives.

• Mature Gorn return to the breeder worlds to “harvest” the strongest, surviving Gorn. The sole survivor is taken to the homeworld or placed in a “liferaft” and sent into space to get even tougher.

• Their civilization has developed warp capabilities and protective gear for being in space.

• Through some unknown adaptation or technology, Gorn can survive being in the vacuum of space.

That’s a long, scary list.

If we hold it against earth-based science, how do some major Gorn characteristics check out? That’s what Dr. Noor is here for.

The “Cold-Blooded” Reptile Thing…

“I was absolutely thrilled to see the Gorn come back, and it’s nice seeing more biology around it, as opposed to just sort of the stereotype of like, oh, it’s a reptile, it’s slow and kind of dumb,” Noor says. “They’re not necessarily slow. Especially that original reptile on a hot planet — there’s no reason for it to be slow. Or even cold-blooded, really.”

Matching Gorn biology with what we know about large reptiles that once dominated our planet, there is an argument to be made that, given their activity level, Gorn are warm-blooded. Since the late 1960s, the old picture of dinosaurs as uniformly sluggish, cold-blooded reptiles has largely collapsed. But dinosaur metabolism was probably more complicated than simply warm-blooded or cold-blooded. Some evidence suggests that several dinosaur lineages had high, bird-like metabolic rates, while others, including Stegosaurus and some other ornithischians, evolved lower metabolic rates.

Theropods — the saurischian lineage that includes Velociraptor, Tyrannosaurus, and living birds — show some of the strongest evidence for high metabolic rates. Other dinosaur groups appear to have followed different physiological paths.

Gorn. Warm-blooded space dinosaurs.

The Social Reptile Thing…

Don’t let your mammal-centric feelings about solitary snakes color your judgment.

“Reptiles are an incredibly broad group,” Noor says. “We see birds working together, sometimes with what seems like a surprising level of intelligence. “And there’s a large body of evidence to suggest that, along with some modern reptiles, many types of dinosaurs lived in social groups, with some possibly hunting cooperatively.”

Remember Jurassic Park?

“It was long and erroneously thought that reptiles were non-social, but that’s just not true,” Noor says. “Part of that comes from comparing parental care between reptiles and mammals and birds; there’s a lot less. One estimate suggests that roughly 97% of reptile species provide no parental care after laying their eggs. That’s a pretty small involvement. But that three percent…

“Just a couple of examples - some Australian skinks live in monogamous family groupings. So not just mother and father, but also their aunts, uncles, and others. They’ll live together socially and interact socially. Alligators in Florida are known for forming large groups of up to 100 animals. Within those groups, you can see courtship dances and other behaviors that suggest a hierarchy. Even tortoises, which people tend to think of as slow, both physically and mentally, have been shown to learn from watching others. It’s not outrageous that we see intelligent and interactive reptiles like these Gorn in the episodes. We should just be thankful we don’t have them on Earth. They seem to have their act together as a species.”

Subscribe now

The Killing Brothers and Sisters Thing…

That’s the Gorn’s very Shakespearean twist - siblicide.

Someone may occasionally want to “kill” a brother or sister, but the Gorn take it to the next level. Shortly after emerging from the host, they go after one another. It’s a creepy, horrific thing as seen in Strange New Worlds.

It’s also seen here.

“There are cases on Earth, but we don’t really know why the animals do it,” Noor said. “This has been studied in boobies — the bird with the unfortunate name — and with them, it’s related to resource scarcity. Basically, the parents produce more offspring than available resources can support, so it’s every baby for itself.”

In the case of the boobies, siblicide results in one hatchling growing larger and stronger than the others, which it then kills or throws from the nest for other predators to pick off.

“It’s certainly not a pretty side of nature,” Noor said. “We tend to see more cooperation between siblings than siblicide. But if resources are limited, it’s better that one makes it than none make it so that the genes can be passed on to the next generation. It wasn’t siblicide, but Star Trek has touched on this idea in the original series episode, ‘The Conscience of the King.’ The crew suspected that the actor was actually Kodos the Executioner, who had put 8000 colonists to death because there weren’t resources for the entire colony.

“Also — siblicide, in a way, could be a hedge against incest and all the problems that can bring, genetically. It’s difficult to mate with your sibling if you’ve killed and eaten all your siblings. The behavior isn’t entirely uncommon, but when it happens between siblings — especially those just hatched — it makes us sit up and notice.”

The behavior is easily explained with the Gorn — the toughest sibling survives. As the stories suggest, mature Gorn return to a hatchling world to pick up the survivor, either to bring them to the home planet or toss them into a “lifeboat” and then into space to keep that “survival of the fittest” thing going.

That’s rough.

The Egg-Spraying Thing…

Gorn hatchlings (and presumably their other forms) spray anything that gets too close to them with a venom that can blind their target but also is loaded with eggs. The eggs enter the host’s body through the mucous membranes or burrow through the skin and start to develop. Sometime later, they hatch and eat their way out of the host.

Hope you’re not eating because this directly correlates to animals on Earth.

“There’s a freshwater mussel genus called Lampsillis in many places that has a little bit of itself that extends outside of its shells and looks like something larger fish would like to eat,” Noor says. “But when the fish comes to bite the lure, the mussel releases a cloud of larvae called glochidia. These latch onto the fish’s gills, where they develop before eventually dropping off. These babies latch on to the fish’s gills, where they feed and grow. They often drop off once they reach a certain size after riding the fish for a few days to months. This fish may suffer a little bit, but usually, they live through the experience.”

But still — very Gorn-like, catching a spray of babies in the face.

But let’s look at the egg spray together with another aspect of Gorn reproductive physiology: the hatchlings are apparently loaded with viable eggs from the start and ready to spray anyone who gets near them.

Not unheard of. Aphids, for example, are “born pregnant.” Other animals follow these lines from birth, but let’s start with aphids as a simple example. Aphids, for example, can quite literally be “born pregnant.” During the asexual part of their life cycle, females produce genetically near-identical daughters through parthenogenesis. Those daughters can already contain developing embryos of the next generation — a reproductive trick called telescoping generations.

Reproduction without a male is called parthenogenesis and is relatively common in insects, amphibians, and reptiles.

“Geckos, whiptail lizards, some snakes, and even Komodo dragons can reproduce asexually if the conditions are all right for it,” Noor said. “Essentially, though, most are just making clones of themselves, if that’s the case.”

In the old ecological shorthand, the Gorn look strongly r-selected. That means producing large numbers of offspring quickly, with the expectation that many will die before reproducing. In r-selected species, many offspring are produced, but not all of them will survive.

It may become clearer if we can pull back and look at it from a distance. Gorn eggs are laid inside hosts, say 20 colonists, each getting four viable hatchlings inside them. 80 hatchlings show up. That’s explosive growth and more than the environment can support, so, through competition for resources (via siblicide), their numbers drop until more hosts are found.

This style of explosive growth might be ringing recognition bells in your head - it’s quite similar to the exponential growth seen in viruses. Put a Gorn hatching in a large city, and let it spray. Each host produces four viable offspring, which then spray others, generation after generation. That was COVID-19.

Virus spread can be measured by its Basic Reproduction number, R₀ (R-naught). During the height of the pandemic, epidemiologists hoped for R₀ to drop below 1, meaning that every infected person infected, on average, fewer than one other person, making it extremely difficult for the virus to spread. During the initial COVID-19 outbreak, we looked at the classic Batman: Contagion storyline for examples of the R₀ of the “Clench” virus and its exponential growth. (archive articles coming soon!)

If each infected host ultimately produced four hatchlings, and each hatchling successfully infected one new host, the process would have an effective reproduction number of 4. Not wildly big, but large enough to do the job. Of course, the hatchlings would also be going after one another, so the analogy’s not perfect.

But if you want to think of the Gorn as intelligent, viral space dinosaurs, that does get the idea across.

With all that in their favor, what stops the Gorn from taking over star systems and, ultimately, galaxies?

I’m going to go with the Federation. And probable Klingons and Romulans, too. Maybe the Borg. Competitors for resources on a galactic scale.

That Gorn Reproduction Thing…

If you were thinking that the Gorn probably can’t rely on cloning alone forever, you may be right — although nature is weirder than that. Some species reproduce asexually for enormous stretches of evolutionary time. But for many organisms, sexual reproduction offers a major advantage: recombination continually reshuffles genetic variation.

A newly established population founded by only one or a few individuals can also suffer from a founder effect, carrying only a fraction of the genetic variation found in the original population. Genetic variation enables adaptation to the environment and protection against threats. If everyone’s genes are the same and a disease is introduced, no one has a defense for it, and the population is wiped out.

Genetic variation usually gives populations more evolutionary options when environments change.

So a single hatchling could establish a small colony of Gorn on a breeder world, but then what? Yes, there would be some mutation when the DNA of the Gorn is being copied, but that wouldn’t be a huge amount. Asexual reproduction will only get them so far. You need sex to really shine as a species.

Come out on top of the heap on a Gorn breeder world, and you may get picked up and taken back home.

To have sex.

Sexual reproduction reshuffles genetic material, producing genetically different offspring and potentially giving populations more ways to respond to disease and environmental change. More robust offspring can better handle environmental challenges. Without sexual reproduction, your species is at a serious disadvantage to those that do.

That Gorn Evolution Thing…

How would you end up with a Gorn world, anyway? In the world of Star Trek, it’s a given - lots of alien species. But let’s play in our sandbox — Earth.

Biologist Stephen Jay Gould famously explained the chance nature of evolution by saying that if you “wound the tape back” on Earth’s evolution, there’s no guarantee you would end up with humans being the dominant species.

Biologist Jonathan Losos, author of Improbable Destinies: Fate, Chance, and the Future of Evolution, explained Gould’s classic line through the use of Disney’s The Good Dinosaur. The Chicxulub impactor — the asteroid that helped wipe out the non-avian dinosaurs 66 million years ago missed the Earth in the film. As a result, dinosaurs remained the dominant life forms on the planet but continued to evolve.

On that Earth, our Gorn analogs — theropods like Velociraptor and troodontids — were doing well — feathered, hunting in packs, and more than likely, demonstrating other bird-like behaviors. Given their anatomy, these bird-like dinosaurs would likely retain the classic theropod body plan, with the head carried forward and the tail acting as a counterbalance, even though they walk on two legs. If their brains and skulls became larger over millions of years, their bodies would have needed to compensate for the shifted center of mass — perhaps with changes to the tail, torso, or posture.

This isn’t to say that a fully bipedal humanoid (or Gorn)-style dinosaur couldn’t have evolved on Earth — it’s just that the theropods were doing pretty well, and the pathway for the evolution of a proto-Gorn wouldn’t have been a clear one. They would have had tough competition from the already-established theropods, which certainly would’ve seen them as a delicacy.

Back to Losos’ theropod-ruled earth…

As Losos explains, there’s no reason to think that these super-smart birds wouldn’t have adopted the use of tools, artificial colorations, tribal society, and even technology. As the illustration from Losos’ book offers:

But as for “pure” Gorn on another world? Noor: “I don’t think it’s a stretch. All of these features we see with the Gorn are at least very close to those we see in the animal kingdom on Earth, and evolution tends to follow its tried-and-true patterns for overcoming environmental obstacles. So it’s not a stretch to think that all of those characteristics we’ve been talking about could have come together in one particular, large reptile. Nothing there is breaking the laws of physics or something like that. I’m just glad it didn’t happen on Earth.”

Like all Strange New Worlds fans, Noor wants to see more Gorn, and hey, if there’s an opening for a science team to set up a research outpost on the Gorn homeworld someday (safety must be guaranteed), sign him up. “I really want to know their origin,” Noor said. “I’m wondering if the Gorn are going to touch on what we saw in the Voyager episode, ‘Distant Origin,’ where some dinosaurs from Earth somehow moved into space and wound up in the Delta Quadrant, and evolved their civilization, or if they’re something entirely new. I hope we get to find out.”

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

First and foremost—and this is the rule for every piece on The Science Of...—this isn’t about criticizing the source material. Opinions about Supergirl (or any film, comic, or television show) are what they are. We’re interested in the science and the questions the story raises.

Cool?

This time, the science starts with a green star.

And those don’t exist.

Which raises a wonderfully nerdy question: if green stars don’t exist... why do DC heroes keep running into them?

First up, a little history…

Subscribe now

TWINKLE, TWINKLE LITTLE GREEN STAR

In Supergirl, Kara and Ruthye find themselves on the planet Barenton. The film places the planet in a binary star system, orbiting two suns: one yellow and one green. We’ll get to the green one in a minute, but first, just to be clear, this isn’t the first green star in DC history.

The first green star to harm a Kryptonian appeared in 1962’s Superman #155, “Superman Under a Green Sun.” The star was originally blue until the villain Drago changed it to green using a satellite (Apparently by adding a yellow filter? Silver Age comics were wonderful). The green light robbed Superman of his powers.

Four years later in Action Comics #337, “The Green Sun Supergirl!” - Kara found herself on a planet orbiting a green sun, which also robbed her of her powers. And in 1967’s Justice League of America #53, Superman casually name-checked green stars as something that can rob him of his powers.

After that, green stars went quiet and didn’t play a role in any Super-stories for decades. They still existed in the DC Universe’s cosmology, as N’Gon did the whole villain origin story recap to Green Lantern in DC Comics Presents #26, “Between Friend and Foe.”

Even though the series was the Superman team-up book, Superman didn’t encounter the green sun.

Green stars then took a very long nap until Tom King and Biliquis Evely’s Supergirl: Woman of Tomorrow #5 in 2021.

In the issue, the planet (and its sun) are known to Kara — and her cousin, Kel-El:

Tom King updates the idea a bit. Light from a green sun now acts much like Kryptonite. As the movie showed, and the comic makes clear, it’s a very painful way to die. A stellar-scale dose of Kryptonite. Literally killer sunburn. Kara needed to find shelter, and fast.

Although she did take a moment to get a couple of good shots in first:

Anyway, I don’t want to spoil any more of the comic. You should absolutely read it. Not making any sweeping judgments here, but in about 99% of cases, the book is better than the movie. This is one of those cases. Plus, it has a super-horse.

Now... let’s talk about the science.

Share

STAR STORIES

Before we get into colors, making the planet part of a binary system with a yellow sun was an odd (clearly she was going to get her powers back), but nice touch — it’s estimated that around half of all Sun-like stars in the Milky Way are part of a system with two or more stars. A planet with two suns isn’t the weird part. In fact, astronomers have discovered planets orbiting binary stars. Nature builds those all the time.

But—making one green and one yellow? That’s the weird stuff.

Aside from the whole “green stars don’t exist” thing (coming up, I promise), that’s also not how binary systems usually work. Stars form from massive clouds of interstellar gas and dust. In a binary system, both stars would form from the same original cloud.

Think of them as siblings. They start with the same raw materials, they’re roughly the same age, and they generally follow the same evolutionary path. Yes, there’s a slight chance that a single star could capture a rogue star that’s wandering through the galaxy, but it’s highly improbable due to the masses and velocities involved. And yes, someone could have built a second star and engineered both stellar and planetary orbits, but that’s less astrophysics and cosmology and more wizardry.

So, as a rule, stars in binary systems are roughly the same age and made from the same material. Exceptions do exist, but on average, siblings, not strangers.

WHY THERE AREN’T GREEN STARS

Disclaimer: Nothing in this article is meant to deny that the color green exists. Grass is green. Kermit the Frog is green. Kryptonite is green. Objects look green because they reflect green light while absorbing much of the rest.

Given the vastness of the universe and all the strange things we’ve discovered, saying there are no green stars sounds... yeah, I know how it sounds.

But there aren’t.

Let’s not talk about stars for a minute. You’re reading this on a screen, right? You’re probably looking at black text on a white background. Here’s the weird part: your screen doesn’t have any white pixels. If you looked at your screen through a microscope, you’d see millions of tiny red, green, and blue lights. Every white page you’ve ever read was really those three colors working together.

Seriously.

Every bit of whiteness on your screen is made up of three tiny red, green, and blue subpixels so close together that your eyes and brain can’t distinguish them individually. Turn all three on together, and your brain says, “Yep. That’s white.”

Your screen is fooling you millions of times per second.

Side note: This is one of those “the universe is ridiculous” facts. A single colored subpixel in a modern phone is only about 10–20 micrometers across—just a bit bigger than a red blood cell. Your phone’s display contains millions of pixels, which means it’s coordinating nearly ten million microscopic colored light sources to convince your brain you’re looking at a plain white page.

Let’s bring this in super close — like eyeball close — to explain what we’re talking about. Your eyes have three types of color-sensitive cone cells—one that responds mostly to red light, one to green, and one to blue. When all three are getting a strong signal at the same time, say, from a star, your brain doesn’t conclude “That’s green.”

It decides: “That’s white.”

It’s the same reason your tablet doesn’t need white LEDs to show a white page. Your visual system isn’t looking for a “white wavelength.” It’s looking at how strongly its three color sensors are responding.

Stars work in much the same way. A star isn’t like a green laser pointer. The light from a star is like the music produced by an orchestra rather than by a solo violin. Some colors are “louder” than others, but all of them are in there.

To keep going with the orchestra idea, cool stars play mostly “red.” Hotter stars play “blue,” and stars like our Sun hit a balance across the entire spectrum to produce a whitish light.

Side note: But Superman and Supergirl get their powers from Earth’s “yellow sun.” Technically, our Sun is white; if sunlight weren’t basically white, a white sheet of paper wouldn’t look white outdoors, but it’s classified as a yellow dwarf star. From space, it’s white, but from Earth’s surface (as seen through our atmosphere), blue and violet light are scattered much more strongly than the longer wavelengths, giving the Sun a slightly warmer, yellowish appearance.

So, what about stars that might produce more green light than any other wavelength? Shouldn’t they look green?

Nope. Because that star would also be producing lots of red and blue light along with its green, and we’re back to where we started: white.

That isn’t an accident. It’s a consequence of the way hot objects emit light, known as blackbody radiation. Something can be red-hot when it is hot enough that some of the energy being released appears as red visible light.

Heat things more, and you can reach orange-hot or white-hot, but you can’t stop at green. Heat things more, and they don’t suddenly switch from red to green light. Instead, they keep producing red while adding more orange, yellow, green, blue, and beyond. The hotter the object gets, the whole spectrum shifts, but it never narrows down to a single color. And in stars, there’s overreach, so stopping on green means you’re also hitting the temperature that produces blue as well.

Red-hot? Absolutely. White-hot? Definitely. Green-hot? Nature doesn’t really do that.

All of this means that a star can absolutely emit a tremendous amount of green light.

Ours does.

Here’s the twist: our own Sun actually produces more light in the green part of the visible spectrum than in any other single color.

It still doesn’t look green.

I know. That feels like I buried the lede.

But stars can’t emit only green light. There’s no pathway for that to happen.

Stars are giant balls of hot gas, and hot objects naturally emit a broad spread of wavelengths, not a single narrow slice of color. There isn’t a temperature at which a star emits only green light.

Side note: “But I’ve seen green light in fire…” Sure have. That’s a completely different process. Stars shine because they’re incredibly hot, producing a broad spectrum of light across many wavelengths (that’s the blackbody radiation we just talked about). Green flames come from excited atoms. Heat an element enough, and some of its electrons jump to higher energy levels.

When those electrons fall back down, they release photons with very specific energies—and therefore very specific colors. For example, sodium vapor produces a sickly yellow-orange light familiar from older streetlights, and copper, when heated, can produce green light. Those colors come from the atoms themselves, not from the overall temperature of the fire.

A star isn’t a giant copper flame - it’s a giant ball of hot gas radiating across the entire visible spectrum.

To make a star look green, you’d have to remove most of its red and blue light before it reached your eyes.

At that point, the star isn’t actually green.

Something else is making it look that way.

COULD A STAR ACTUALLY LOOK GREEN?

Yes. Sort of.

But only under very specific circumstances. Let’s look at three: one that’s real, one that’s probably not, and one that borders on wizardry.

1. When viewed through specific atmospheric conditions. The Sun sends a tremendous amount of energy toward Earth, but our atmosphere acts like a bouncer at a club. Some wavelengths are absorbed before they ever reach the ground; others are scattered in different directions, while visible light mostly makes it through.
   
   It’s why the Sun can look different depending on where you’re looking at it from. In space, it’s white. At noon, it looks bright yellow-white because there’s not a lot of atmosphere between you and it. Compare that to mornings or evenings, when you’re seeing the sunrise or sunset, and the amount of atmosphere you’re looking through to see the Sun is considerably thicker. The more atmosphere sunlight has to travel through, the more opportunities there are for that light to be scattered, absorbed, or bent.
   
   Could a planet have a weird atmosphere that could remove incoming red and blue light from a white star, leaving mostly green? Sure. It’s a big universe. But - if the Sun looks green, everything illuminated by it would probably look strange, too. Anything green would look green. White objects would look green; red things would look dark or black (with no red light to reflect), while yellow things would look green. It would be a very strange world.
   
   Side note: “Wait... what about the green flash?” That’s real, too. Under just the right conditions at sunrise or sunset, the upper edge of the Sun can briefly flash green for a second or two. It’s caused by Earth’s atmosphere bending (refracting) different colors of light by slightly different amounts, while also scattering blue light more strongly than the others. For a brief moment, the green portion of the Sun’s light reaches your eyes just before the rest of the Sun disappears below the horizon. The Sun hasn’t suddenly turned green—our atmosphere has briefly played a neat optical trick on us. It’s one more example of an ordinary star appearing green without actually being green.
   

2. Better eyes? Mantis shrimp have up to 16 kinds of photoreceptors compared to our three, giving them a visual system very different from ours. What if we’re saying “there are no green stars” because our eyes don’t see green stars as they really are?

   

   Let’s take our space-faring mantis shrimp. Hold it up, show it to the sun, and ask what color it is; it would not say it was green, green-white, or greenish, despite the Sun emitting more green light than any other color. The mantis shrimp would almost certainly distinguish subtler differences between stars than we can, but a Sun-like spectrum is still a broad spectrum. Better eyes don’t change the physics of what the star is emitting.
   
   And also, sixteen photoreceptors sounds like mantis shrimp would have super color vision. Weirdly... they probably don’t. Probably just different, not better.
   

3. A giant filter. Your best bet, but highly unlikely, is to put something between the observer and the star that would make it appear green. You wouldn’t build a green star—you’d build a green view of an ordinary star. If your star is white, put a giant green filter in front of it, something like a green Dyson sphere. An enormous cloud of nanoparticles. A bespoke planetary atmosphere designed to absorb red and blue. You know, easy stuff.
   
   But at that point, you haven’t made a green star at all. You’ve made a perfectly ordinary star wearing green sunglasses.

Which brings us right back where we started. Green stars don’t exist. But under the right conditions, perfectly ordinary stars can do a very convincing impression of one.

Oh, and to give that final answer, why does Supergirl keep finding them? I can only imagine the storytelling, the mythology. She and Superman are god-like, but there are planets out there where they can die just because the sun shines on them. And Kara’s reveal from Woman of Tomorrow? That someone made a green star as a trap for Superman? Nice - it speaks to the efforts and resources going into stopping Superman (and Supergirl) and all that they stand for. I like the idea a lot. All of this? Explaining that green stars can’t exist? Didn’t take away any of my enjoyment of the graphic novel or the movie. If you ever find yourself in a place like this, remember, you never yuck someone else’s yum.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four.

Galactus.

The fact that you read that name and don’t get a knot in your stomach is one reason you know you’re living in “our” universe rather than the Marvel Universe.

The other way you know you’re not living in the Marvel Universe?

Our universe. Literally. It doesn’t fit the big guy’s origin story.

Let’s make sure we’re all up to speed here.

GALACTUS 101

First appearing in Fantastic Four #48 (1966, by Stan Lee and Jack Kirby), Galactus has been a constant in the Marvel Universe for nearly 60 years. But Galactus wasn’t born in the “current” Marvel Universe. Instead, as his origin explains, Galen of Taa comes from the universe that preceded ours.

Side Note: A little bit of Marvel Universe 101: the current Marvel Universe is the “Eighth Cosmos,” or the eighth iteration of reality. The present cosmos is a nearly identical copy of the Seventh Cosmos, which was destroyed at the start of Secret Wars (2015). In 2021’s Defenders limited series, creators Al Ewing and Javier Rodriguez took a disparate group of heroes backward through the previous Cosmoses to stop at the Third before ending their adventure. Each previous Cosmos was more primal and more…trippy. Nevertheless, it was a great story, and its sequel, Defenders Beyond, explains the Second Cosmos and beyond.

Back to Galen - he was a scientist and explorer, obsessed with finding a solution for the wave of death that was killing off all the life in the universe. While seeking answers in space, Galen and his ship are pulled into what seems to be a Big Crunch, the theoretical opposite of the Big Bang. “Inside” the Crunch, Galen bonds with the Sentience of the Universe and survives. As a result, Galan has VIP seating for the Big Bang that starts the Marvel Universe (the Eighth Cosmos). With some aiding and abetting by the Watcher, Galen gestated inside an “egg” made from the remains of his ship for a few billion years, finally debuting as Galactus. From there, he started eating planets.

And running afoul of Earth’s superheroes.

There’s more to Galactus’ story, but that’s for another day. Let’s put on our cosmologist hats.

Galactus’ story involves a specific cosmology model we don’t see in our universe. For over 50 years, data have suggested that our universe started with a “hot” Big Bang. The Big Bang was followed by Cosmic Inflation. Since then, the universe has expanded and cooled.

In Galactus’ cosmos, reality is cyclic. A Big Bang. Billions of years of expansion. Then expansion slows, stops, and reverses. Eventually, all matter and energy fall back together faster and faster, resulting in a singularity. That singularity is the point from which the “Big Bang” kickstarts the next universe. And the cycle repeats.

A cyclic cosmos has all kinds of implications—enough for its own article—but our observations point somewhere else. But as our understanding of such things stands, ours is not a cyclic universe. And it all comes down to the evidence.

We have overwhelming evidence for the hot Big Bang and strong evidence supporting Cosmic Inflation.

Share

THE BIG BANG.

Since Edwin Hubble’s work in 1929, we’ve known space is expanding. His observations showed that distant galaxies are redshifted. That is, they’re moving away from us. The light from galaxies moving away from us is “stretched” slightly, which pushes it towards the red end of the visible spectrum.

This stretching and changing what we experience is the same Doppler Effect you hear when an ambulance goes by - as it comes toward you, the siren is higher pitched, but as it moves away from you, it’s lower pitched. The waves stretch as the ambulance moves away, and your ear experiences fewer of them per time (frequency). Lower frequency means lower pitch.

Light behaves the same way.

In the late 1990s, astronomers studying distant Type Ia supernovae discovered something unexpected: the universe wasn’t just expanding. Its expansion was speeding up. Later observations with the Hubble Space Telescope and other observatories confirmed the picture.

The universe was expanding, and the rate of acceleration was increasing. By the time you’re done reading this article, galaxies moving away from us will be moving faster than when you started reading it.

Side note: stars and galaxies aren’t moving away from “us,” specifically. Everything is moving away from everything. Space itself is expanding. The light traveling through space has to travel through more space - same light, larger volume, the wavelength stretches.

Another side note: the galaxies near ours aren’t moving away from us. While gravity holds the stars of the Milky Way, Andromeda (home of the Skrulls in the Marvel Universe), and a bunch of smaller nearby galaxies together, it also holds our local group together. So we all move together more or less as a unit.

While you can run the expansion information forward in time to a far future of cold, dark skies and the death of the universe, we want to run it backward.

Wind back the clock on an expanding universe, and you end up with a smaller and smaller universe, “ending” (er, beginning) with the universe in an unimaginably hot, dense state roughly 13.8 billion years ago.

Earlier than that, our current physics starts to break down. We don’t yet know what, if anything, came “before.” But the energy of that early universe wasn’t an even, flat, calm pool. There were fluctuations - quantum ripples. Imperfections. For some reason, one of the fluctuations expanded. Fast. Everything, even the fluctuations, spread quickly. Space itself expanded faster than light. Cosmic Inflation.

In a super-simple version: the universe cooled, and energy produced matter and antimatter that would eventually make up today’s universe. Then, over a period of time, matter, pulled together by gravity, begins to clump along the former fluctuations — which also stretched. Give it more time, and enough matter collects, falls in on itself, and ignites, birthing the universe’s first stars. In areas with a lot of matter, galaxies form. Let that clock run forward about nine billion years, and a collection of gas and dust in a rather ordinary galaxy gets busy making a sun and a solar system. We call that spot home.

This all sounds like a cool story — conveniently cool to some — but with the 2009 launch of the Planck Telescope, the story got a lot more real.

Planck looked at the universe over and over, examining the temperature and its variations. The idea was simple — if the universe were once a small, hot clump of matter that expanded quickly to form what we see today, that heat would still be around. Not as what we think of as “heat,” but energy. Ancient energy that’s cooled and cooled. Think of it as being able to tell that your stove was on by looking at the burners with a thermal camera. The burners are no longer red (visible light), but you can still see some energy (infrared - “heat”).

Planck’s image complemented and refined the “WMAP” image from NASA’s Wilkinson Microwave Anisotropy Probe, which had been collecting similar data since 2001.

In glorious detail, the image from Planck shows the cosmic microwave background radiation (CMBR). The heat of the early universe has cooled to the point that it’s not “heat” as we think of it but a form of energy with longer wavelengths and a lower frequency - microwaves.

The image often throws viewers because of its oval shape. In reality, the CMBR image is a 360-degree view of the entire universe from Planck’s point of view. And to fully grasp the idea, think of it in 3D. You’re viewing it, but also, you’re in it.

Take a minute if you need to.

The image’s color variations show tiny temperature differences - places where the universe is just a little “warmer” or “cooler.” Those tiny temperature variations are essentially snapshots of quantum fluctuations that were stretched to cosmic scales during Inflation. Moreover, the fluctuations in the CMBR coincide with regions where we see the largest collections of matter in the universe.

Cosmic Inflation is a model to predict what the universe should be like. Observations have matched the model.

Long story short, that’s how we know the hot Big Bang happened and why Inflation fits the evidence so well. And given that the universe’s expansion is speeding up, the evidence points to the theory that everything will keep expanding, ultimately cooling and dying. That’s the heat death of the universe.

Some versions of Inflation naturally allow for a multiverse (more on that in another article).

Subscribe now

OTHER CONTENDERS

Given the evidence that has accumulated over the years, our universe doesn’t appear to support Galactus’s origin. For that, you’d need an alternate theory. There are three main contenders, two of which could theoretically support Galactus: Big Bounce and Conformal Cyclic Cosmology.

Both theories are born of their proponents’ dissatisfaction with Cosmic Inflation and claim to offer a more straightforward explanation of the Big Bang and the universe’s history. Your mileage may vary, of course.

Of the two, the Big Bounce is the simplest to understand. After an indeterminate period of expansion, the universe begins to contract - the Big Crunch mentioned earlier. Everything collects into a super-hot, super-dense point. From there, the universe would “bounce” in a Big Bang.

The Big Bounce theory suggests that time has no beginning and no end. Our perception of all reality is just this period, in this particular cosmos. Ultimately, it will collapse, starting another, and this cycle will happen forever. Literally forever.

Putting Galactus into this model is easy — the “Seventh Cosmos” of the Marvel Universe was just the universe before ours that collapsed. The Eighth is just the new universe after the bounce.

The other idea that supports Galactus, Conformal Cyclic Cosmology (CCC), follows a similar theme but differs slightly.

First suggested and promoted by Nobel Laureate Roger Penrose in his 2010 book, Cycles of Time: An Extraordinary New View of the Universe, the idea is a deep dive into cosmology and quantum mechanics, but it does have some relatively easy-to-grasp (but still weird) main points.

The history of the cosmos breaks into what Penrose calls “eons” - marked by a Big Bang and then expansion. At some point, the universe will expand to its maximum size, cooling as it does. Along the way, most remaining matter ultimately ends up in black holes. The black holes will continue to cool and slowly evaporate via Hawking Radiation.

Except for photons. This makes a cold, dead universe look like the Big Bang model. A new Big Bang will kick up from this state, starting another of Penrose’s eons.

In CCC, Penrose explains, there would be “leftovers” of the universe previous to ours, observable in the CMBR, “bruises” in the CMBR left by the final evaporation of black holes during the last eon. Penrose calls these “Hawking Points.”

These signals - the Hawking Points - are where things get ugly. Working with researchers around the globe, Penrose insists they can be observed. However, many astrophysicists claim that Hawking Points can’t be seen in a standard interpretation of CMBR data. You can see Penrose’s “Hawking Points” if you look at the data while — metaphorically — squinting, cocking your head at a specific angle, and humming a middle C note while exhaling.

The more technical term is that Penrose’s results are based on an analysis of the data “in a scientifically unsound and illegitimate fashion,” according to astrophysicist Ethan Siegel.

The third contender for the universe’s origin involves the creation of a “Mirror Universe,” and that’s something for another day.

BUT WHY GALACTUS AND THE BOUNCE?

Before we wrap up, let’s take a quick look at how Galactus came to be. According to Marvel lore, Jack Kirby wanted to create a villain above mortals—a godlike force of nature that couldn’t simply be punched into submission or reasoned with. Kirby drew the pages for the legendary Galactus Trilogy (Fantastic Four #48–50), and Lee put words to the images. Galactus didn’t receive a true origin until three years later, when the pair reunited for The Mighty Thor #168–169 (1969). There, they revealed Galen of Taa, the last survivor of a previous cosmos, reborn into the (current) Marvel Universe after surviving that reality’s Big Crunch.

In telling Galactus’ origin, Lee and Kirby were doing what they had done for years with characters like the Hulk and the X-Men: building superheroes from contemporary science. They weren’t trying to predict the future of cosmology. They were using one of the legitimate scientific ideas of their day to tell a bigger story.

For much of the twentieth century, an oscillating universe was a legitimate cosmological model. Scientists debated it alongside other competing ideas about the origin and fate of the cosmos. Given Kirby’s curiosity and Lee’s appetite for current ideas, it’s not hard to imagine the concept finding its way into Marvel’s biggest cosmic character.

Today, the evidence points somewhere else. But Galactus’ origin isn’t bad science—it’s a time capsule. It’s Lee and Kirby taking one of the biggest scientific questions anyone could ask and building a god out of it. That’s pretty wonderful.

NO GALACTUS NEED APPLY

The idea of a hot Big Bang followed by Cosmic Inflation has withstood challenges for years. Beyond that, research provides additional data supporting the theory. As evidence has piled up in favor of the idea, the hot Big Bang followed by Cosmic Inflation has moved from one of a field of contenders to explain our universe to the top of the stack, the spot from where future science will start. It’s the best model we have, the one that the data supports.

Changing an accepted theory is simple: just bring the evidence. That’s all. Just show evidence that other researchers can view, independently reproduce, and reach the same conclusion.

There are still unanswered questions about the Big Bang. We’ll never be able to directly observe the Big Bang itself, no matter how good our tools are. The superheated plasma just after the Big Bang is opaque. The best we can do is examine the universe’s evidence and develop theories that align with observations.

That’s how science works. Theories either solidify or change as new data comes to light. The data supports a hot Big Bang followed by Cosmic Inflation, without requiring earlier universes. We’re bound to learn more as we go, but in the end, all we can do is follow the universe’s lead.

And for our universe, that means no Galactus.

Sorry, big guy.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

If you haven’t seen Flow, you should; it’s wonderful. Trailer at the end of the article.

Cats and dogs are different.

I know, I know. But go with me here.

In the 2024 film Flow, we’re dropped into a post-apocalyptic world where all humans have vanished, apparently almost overnight. No bodies. No evidence of war or large-scale destruction. People are just...gone. This also isn’t Pixar or Disney. The animals don’t talk. In fact, there’s no dialogue at all.

Cities are crumbling, forests are reclaiming roads, and the water is rising.

And quietly moving through it all is...a cat. The unnamed cat doesn’t look futuristic. It isn’t mutated. It doesn’t have wings. It looks just like…your cat.

Yeah, but should it?

To answer that, we actually need to go back about 30,000 years.

The Animal That Domesticated Itself

When we think about domesticated dogs and cats, we’re actually talking about two completely different evolutionary stories.

Our domestication project with dogs began somewhere between 30,000 and 40,000 years ago, when wolves started hanging around the camps of our hunter-gatherer ancestors. It worked because both species were after the same things: food and security. Over time, we began helping each other.

Over time, wolves with gentler dispositions (and eventually more puppy-like features) got more food and were allowed to stay closer to the fire. Better-fed, more secure wolves reproduced more successfully, and over generations, the traits that made them friendlier spread through the population. By roughly 15,000 years ago, dogs were established companions across much of Eurasia, and our domestication project really took off. Once dogs were part of human society, we began intentionally breeding them for specific jobs: protection, herding, hunting, sled pulling, and eventually companionship.

The results of that project are obvious today. Every dog, from a Chihuahua to a Great Dane, shares a common ancestor with the gray wolf. Even the one that snores and farts under the table while you’re watching a movie.

Cats? Their story is completely different.

Cats joined the human story a few thousand years after dogs. Wildcats were doing just fine on their own. They had no reason to seek us out, and they were understandably wary of humans. By the time dogs were firmly part of human society, our shift from hunting and gathering to agriculture accidentally created an opportunity that wildcats couldn’t ignore.

Part of agriculture involves storing grain; stored grain attracts rodents, and rodents attract wildcats. Circle of life.

We eventually shaped wolves into the dogs we needed. We never really set out to create cats. Biologists call this commensal domestication. Human settlements benefited the cats. Cats benefited humans.

In a very real sense, dogs became our invention. Over thousands of years, we shaped them into hunters, guardians, herders, sled pullers...and eventually, companions small enough to ride around in a designer handbag.

Cats chose to become our neighbors. We simply took care of the ones that didn’t immediately run away or try to maul us.

If you think about it, our relationship with them looks a lot like the workplace:

Dogs are employees; cats are contractors.

Both get paid, but only one of them pretends they don’t need the job.

From Wolf to Pug, From Wildcat to…Cat.

All the dog breeds that populate the world today? Yeah, that’s on us.

As mentioned earlier, our intentions for cats were practical. We needed partners to help us hunt, herd livestock, guard our camps, and eventually even follow animals into burrows (looking at you, dachshunds). Selective breeding isn’t fast, but given enough generations, it works. Breed one dog with desirable traits to another with desirable traits and, hopefully, their puppies inherit both. If not, try again.

Over and over, for thousands of years.

If you’re a cat person, you know this. You quickly get used to the idea that the feline sharing your home would probably do just fine without you. Every now and then, you catch a glance that expresses your cat’s sheer tolerance of being near you.

Cats didn’t need to change.

Meet the African wildcat, Felis lybica, the primary wild ancestor of today’s domestic cats.

Yup. That’s basically...a cat.

There are two reasons for that. First, cats joined us roughly 20,000 years after dogs. Second, they never needed a different job. They’re still doing exactly the job they applied for: hunting rodents. Anything they do other than hunting rodents is just waiting to hunt rodents. There are even suggestions that cats are neurologically plucking at our heartstrings, endearing themselves to us with their baked-in cuteness.

Domesticated cats have undergone surprisingly few physical changes. Compared to African wildcats, they have slightly smaller brains and a handful of subtle skull differences, but that’s about it. Otherwise, the cat sleeping on your couch is basically a wildcat with better customer service.

As grain stores spread throughout the ancient world, so did cats. One of the earliest pieces of evidence for the human-cat partnership comes from a 9,500-year-old burial site on Cyprus, where a person was buried alongside a cat. Wildcats weren’t native to Cyprus, so someone intentionally introduced them there. Whether it arrived as a pest controller, a companion, or both, it was important enough to be buried beside its human.

Cats became especially important in ancient Egypt, where they protected grain stores, became household companions, and were eventually associated with the goddess Bastet.

From there, cats traveled with merchants, farmers, soldiers, and sailors. They spread along trade routes, aboard Roman ships, and later with European explorers, becoming one of humanity’s most successful traveling companions.

Because domestic cats spread so recently and so successfully, scientists still view them as a single global population with relatively little genetic differentiation.

But there was almost a different form of cat hanging around humans…

Subscribe now

China Tried Its Own Cat Partnership

Around 5,400 years ago, leopard cats began appearing in archaeological sites associated with farming villages in China. They also show up in ancient Chinese art. This relationship appears to have lasted for centuries. Then, sometime during the first millennium CE, leopard cats gradually disappeared from the archaeological and cultural record, replaced by domestic cats descended from African wildcats.

The reason leopard cats moved into ancient Chinese settlements was probably the same one that drew African wildcats into villages in the Near East. Like other human civilizations, agriculture created the same food chain:

Villages → grain stores → rodents → leopard cats.

And…

…nothing.

It took centuries, but the great leopard cat experiment eventually fizzled.

It was one of those rare cases of evolution running the same experiment twice.

Once, with African wildcats, we got the cat sleeping on your couch.

The second time, with leopard cats in ancient China, the experiment simply...didn’t take.

African wildcats and humans formed a successful commensal partnership. Leopard cats and humans, for reasons we still don’t fully understand, didn’t.

Leopard cats didn’t disappear from China; they simply disappeared from human settlements and the archaeological record.

Side note: There is absolutely no evidence that a leopard cat, after years of being antagonistic towards the Emperor, scratched him one too many times, and the Emperor decreed that there would be no more cats in houses. It’s a kind of funny story, but no evidence.

Nearly a thousand years later, domestic cats descended from African wildcats arrived via long-distance trade, probably by the Tang Dynasty. Those are the ancestors of the house cats living in China today.

Would Cats Survive Us?

So let’s go back to the world of Flow.

If humanity disappeared tomorrow, how would dogs do?

Many working breeds would probably adapt reasonably well, just as we see in Flow. Others would struggle almost immediately. Bulldogs, pugs, and many toy breeds would find themselves on evolution’s very short list of unfortunate design choices.

Over many generations, without human breeding, the boundaries between dog breeds would gradually disappear. The end result would most likely be a medium-sized, lean, athletic dog with upright ears, a narrow muzzle, and a short coat, with many populations likely hunting cooperatively when conditions favored it.

Side note: What was just described can now be observed: about 75–80% of the world’s dogs aren’t pets. They’re free-breeding village dogs. Across Africa, Asia, South America, and parts of Europe, they’ve already converged on almost exactly the same body plan: medium-sized, tan or brown, short-haired, pointed ears, narrow muzzle, athletic build. That’s kind of cool from an evolutionary perspective.

What about cats? Cat people already know the answer: cats would do just fine without us.

Cats are fully domesticated, but they’re much less changed by domestication than dogs are. They still know how to stalk, hunt, climb, and survive on their own. They tolerate partnerships with humans remarkably well, yet retain many of the skills that made their wild ancestors successful. They’re remarkably unchanged despite their millennia-long relationship with us. The millions of feral cats living around the world demonstrate just how quickly domestic cats can return to hunting and independent living.

Over generations, feral populations would likely become leaner and warier, gradually losing traits that only make sense in human homes. But overall, they probably wouldn’t look dramatically different from today’s cats.

Dogs would spend generations becoming more like their ancestors.

Cats?

They’ve never wandered very far from theirs.

Evolution Doesn’t Care About Ownership

Given our long relationship with cats and the role they play in our lives, it’s easy to think that we “created” cats the same way we created dogs.

That’s not the way the science rolls here.

We didn’t choose cats; they chose us. We built an ecosystem that rewards one particular type of wildcat — one that does the job, isn’t too scared of us, and responds to rewards. The cats stayed because it worked.

Civilization changed the world and undoubtedly created the dog, but it barely changed the cat.

Flow imagines a world after us.

Ironically, one of its most believable characters may be the one we’ve been living beside for more than 10,000 years.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

The phenomenon that would become the film Backrooms was seeded on a paranormal-themed 4chan message board in 2019, when users were asked to “post disquieting images that just feel ‘off.’” The initial post was followed by the now iconic image:

As a follow-up to the image, an anonymous 4chan poster wrote:

If you’re not careful and you noclip out of reality in the wrong areas, you’ll end up in the Backrooms, where it’s nothing but the stink of old moist carpet, the madness of mono-yellow, the endless background noise of fluorescent lights at maximum hum-buzz, and approximately six hundred million square miles of randomly segmented empty rooms to be trapped in

God save you if you hear something wandering around nearby…because it sure as hell has heard you.

The thread went viral and led to Kane Parsons (then 16 and posting as ‘Kane Pixels’) creating the web series, which, over multiple episodes, built an entire mythology atop the original idea.

Parsons’ version is by far the most popular, with secret organizations, characters, and monsters inhabiting a world just out of reach.

But let’s get something straight - Backrooms works not because it’s another monster movie. Even before Parsons added monsters, secret projects, and an entire mythology, the original image was already unsettling.

And now there’s a movie. Sure, it’s called a horror movie, but is it? Traditional horror movies give us slashers, maniacs, monsters, and ghosts. But The Backrooms gives us…endless office space as the main “character?”

Why is an endless set of rooms scarier than a monster?

Yes, it’s a liminal space — somewhere that’s a transition between one area and the next, and yes, in our experience, it should be occupied by…something. It’s also uncanny. Useful explanations, but they don’t really explain why these places feel so weird and unsettling.

To get into the core creepiness of Backrooms, we need to dig into your brain (not literally) and look at our own operating systems we rely on every day:

• Navigation

• Threat Detection

• Memory

Break one, and things get confusing. Break all three, and things get scary. The Backrooms does exactly that.

Let’s get into the neuroscience of the Backrooms.

There’s a Hidden GPS in Your Head

Constantly, whether you think about it or not, your brain is building maps of your physical surroundings. Normally, it doesn’t even reach conscious awareness, but if you try to feel it, it’s there. Go for a walk — without “knowing,” you have a basic idea of the area around you, if there’s a path coming up, the rough location of large objects, and a million other small details that you’re not looking for. And it’s not just an “in nature” thing. Your brain will build representations of the area around you in buildings, whether they’re large open spaces like a Costco warehouse or more constricted areas, like hotel hallways or office spaces.

It’s the “wait, this isn’t right…” you feel when you get off on the wrong floor in a building. You didn’t bother to memorize all the landmarks and specific bits of stuff, but your brain did, quietly labeling them ‘my floor.’

It’s just another service offered by our brains, a jelly-like organ that are always trying to make sense of the world around us.

One of the major hubs involved in this process is the entorhinal cortex (in your temporal lobe). Broadly speaking, different parts of the entorhinal cortex help process information about objects, locations, distances, and spatial relationships. That information is fed to the hippocampus, which smashes it all together and combines it with existing memories to make mental maps of your surroundings.

Oh, and it’s far cooler than it sounds.

The entorhinal-hippocampal region also has specialized neurons called grid cells, border cells, and place cells. Grid cells are like biological graph paper in your brain upon which your surroundings are overlaid; border cells inform the brain when it’s near the border of a specific location or environment, and place cells are the “you are here” marker inside your brain. Combine these three types with head direction cells that keep track of which direction your head is pointed, and you’ve got…

…I know. It sounds like I just described the GPS on your phone, down to the dot’s direction on the map. That’s because I did.

Your brain builds models of the spaces it’s in. Go into a building, and your hippocampus gives a thumbs up — it knows what to expect from a “building:” hallways, doors, water fountains and other landmarks. Meanwhile, your sensory organs are feeding your brain specific information — including landmarks — that make this “building” unique in the hippocampus’ collection of “buildings.”

Internal navigation loves landmarks.

This process is going on all the time. We don’t notice it.

Break this process down, and things get uncomfortable.

That’s what the Backrooms do — they short-circuit the brain’s mapping system. The Backrooms are nothing but repetition and sameness. Rooms feel familiar, but not unique. A hallway should help you orient yourself. A landmark should help you build a map. A room should tell you where you are. In the Backrooms, every new piece of information feels useless.

The Backrooms fight the brain’s machinery that’s trying to build a map.

Whether you’re watching it or experiencing it, you’ll experience disorientation, uncertainty, and a loss of control. This is spatial anxiety, and we’ve all felt it at one time or another. The brain’s trying, but cannot make sense of the world it’s in. It doesn’t know whether it’s making progress by moving in a certain direction or just walking in circles.

If you knew you were in a maze, you’d probably feel a little better with that knowledge, but the Backrooms don’t look like a maze. They just…continue.

A nowhere of endless sameness.

Subscribe now

Uncertainty Is Worse Than Danger

Let’s say you’re urban exploring in an abandoned mall. Two scenarios:

Scenario A: Standing in front of an abandoned Spencer’s (no judgment), you look down the way, and in the dim light, you see a figure. Slowly, they pull a machete from behind their back.

Scenario B: Standing in front of that Spencer’s (starting to judge), you hear a noise from the mall’s second floor. Were they footsteps? A metallic tap-tap-tap? Just the structure settling, adjusting to the temperature?

It’s the secret sauce of scary movies. You can reveal or withhold (and hint). Both produce different responses, and you can certainly think of movies that did either one. But of the two, Scenario B often creates longer-lasting stress. It keeps your defensive system active because your brain hates unresolved threats. It wants to know, and it wants to know now.

Your brain was made to handle stress that could be easily identified and dealt with, not unresolved stress and anxiety.

When the brain detects a threat, it activates the sympathetic nervous system, triggering the well-known “fight, flight, or freeze” response. The response’s main hallmarks are increased vigilance, hyper-awareness, the release of stress hormones, and a heightened startle response. For a revealed threat, the brain evaluates and gets things rolling. The adrenal glands have dumped those stress hormones into your bloodstream, and you’re ready to throw hands, run, or be literally paralyzed with fear.

But when the threat is never resolved, the system never fully powers down. It’s still there, waiting and ready. You cannot relax. In a sense, that’s a good thing. Your nervous system is working exactly as designed.

But when that state keeps going and going and going, it’s exhausting. And uncomfortable. You scan the surroundings more. Movement is slowed, and your sensory awareness goes through the roof.

And the Backrooms rarely present a visible threat. Just strange sounds, hints of distant movement, empty corridors, and endless uncertainty. Your nervous system becomes trapped in that same endless anticipation. It’s Scenario B, stretched out indefinitely.

The scariest part from this side of the neuroscience of the Backrooms isn’t that something might be there. It’s that your brain never gets permission to stop looking.

Side Note: Early video games accidentally discovered something horror filmmakers already knew: what you don't show can be more unsettling than what you do. Fog hid technical limitations, but it also forced players to imagine what might be lurking just beyond the edge of visibility. Silent Hill was and still is creepy as hell.

This Place Feels Familiar

The third gut punch the Backrooms makes to our brains?

Nostalgia.

Again, your brain is desperate to make sense of its surroundings, and dammit, the Backrooms feel…familiar.

But they’re not.

Moving through the Backrooms, they feel like schools, or office buildings, or hotels, or waiting rooms. Spaces you’ve been to many times and have memories of. But this? This place isn’t identifiable. It doesn’t match any of the patterns your brain wants to compare it against.

Usually, when your brain asks, “Wait — have I seen this before? Can I place it in my memory?” the answer is yes. You’ve been there before, or the setting is similar to other places like it. But the Backrooms break that process.

Several memory systems come into play here:

• Autobiographical memory - your life’s narrative and identity

• Place memory - the collection of places where things occurred

• Nostalgia - an emotional response often built from the first two.

With the Backrooms, none of these are working fully. You might kinda remember having seen a place that kinda looks like this. Kinda.

And that “kinda” is the key to the unsettled nature of the Backrooms.

Neuroscientists call this familiarity without recollection. It’s not “I remember this,” it’s “I should remember this.”

And that’s uncomfortably close to “I almost remember this.”

Your brain, when seeing the various locations of the Backrooms, gets a ping of familiarity, but none of the reward that comes with recognition.

Because those memories remain fuzzy, the Backrooms take on that uncanny feeling. It’s like you’re walking through a dream you forgot you had, or a school hallway that never existed, or a location from your childhood that you realize you misremembered. It’s like when you have a dream about walking through your home, and you see a door where you know, for a fact, no door exists. Unsettling, yeah?

Or think about the early days of video games. Producers offered games with ambitions that exceeded the hardware’s capabilities. How to make something creepy (that the processor couldn’t reliably render?) Add fog. Keep the immediate surroundings somewhat familiar, but mist things out starting at the mid-distance.

The Backrooms, created from bits and pieces of real environments, feel like that — a damaged memory. Not something fake that your brain could suss out immediately, and not something real, but something in between.

All your brain wants to do is make sense of the setting and find a match somewhere in storage, and it’s trying every tool it’s got, but none of them work.

Subscribe now

The Monster Paradox

This is more observation than science, but many Backrooms fans think that the entities that show up are the weakest part of the lore of Parsons’ Backrooms.

I know, I know — “But it’s a horror movie! There should be monsters!”

But — go with me here. The monsters in the Backrooms change the idea from environmental horror to a problem with a potential solution. The monster (or entity) gives certainty to an uncertain, unfamiliar world that is attacking the three systems of your brain that you rely on, day-in, day-out.

Now, this unsettling liminal space has a rock. An anchor. You know that:

• Something is chasing you

• It wants _____

• It behaves like this…

Your brain, which has been desperate to make sense of the world it’s found itself in, can start making rules. As a result, the mystery shrinks. It’s fear of a thing versus fear of a place. One hits harder - consider the creepiness of:

• An abandoned hospital

• Empty schools at night (I’m a teacher, and they still freak me out)

• Endless stairwells

• Dense fog

The environment is the antagonist. It’s the threat to your understanding of the world, attacking your brain.

Monsters? Hell, monsters can be chased and killed, demons exorcised, invaders sent back to where they came from, but what do you do when the world itself is the enemy? Not in the active sense, but in the passive, like the Backrooms.

The real “monster” of the Backrooms isn’t a traditional monster that appears in the stories. It’s not an entity.

The monster is uncertainty itself. The architecture of the Backrooms is the predator. The environment has trapped your brain inside a problem it cannot solve.

Your Brain Was Not Designed for the Backrooms

Every day, your brain relies on three systems to function within its environment: navigation, threat detection, and memory. The Backrooms attacks all three.

To experience the Backrooms is to know what it’s like to be unable to build a reliable map of your surroundings in your mind, to be unable to determine whether danger actually exists, and to be unable to determine whether a place is truly familiar.

Mess with any one of them, and things get weird. Go after all three, and that’s the perfect storm — hitting the audience exactly where evolution left us vulnerable.

The result of watching the Backrooms isn’t just fear. Traveling through the yellow rooms creates a sense of cognitive disorientation.

Unlike so many horror stories, the Backrooms aren’t terrifying because something is hiding in the darkness. They’re terrifying because the darkness has moved into systems we normally trust without thinking: our sense of place, our sense of safety, and our sense of memory. The moment those systems stop working, even a fluorescent-lit office can become a nightmare.

The Backrooms aren’t a haunted house.

They’re a haunted operating system.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four.

all images © Adult Swim

In its run of over 85 episodes (to date), Rick and Morty have shown us a huge variety of planets – weird, obscene, funny, normal, big and…small.

Looking back on the Season 2 finale, “Wedding Squanchers,” Rick, Morty, and the family find themselves on the run after a wedding turns into an ambush for Rick and his friends. After telling his family that they can never go back to Earth, Rick starts hunting for replacement homeworlds, and…long story short…they settle on Dwarf Terrace-9, a tiny version of Earth.

According to Rick, the planet is one of three that is at least 90% like Earth and is outside federal jurisdiction.

The family lands, and they are basically giants on Tiny Earth. As they’re there, they are walking normally, like they’re on Earth – with normal Earth gravity.

You can see where this is going, can’t you?

Yes, this is a nod to Antoine de Saint-Exupéry’s The Little Prince, whose asteroid (Asteroid B-612) is “scarcely bigger than a house. And we could do the science of that, but let’s focus on Rick and Morty instead.

Let’s get into the science of Rick and Morty’s Tiny Earth and see if we can figure out its gravity and if you’d be walking around like it was no big deal.

Subscribe now

Physics ahead…

…but it’s easy. Trust me. I teach this stuff.

So – the morning after landing, when Rick comes in and asks if he’s smelling bacon, the family tells him that they had discovered (and subsequently made extinct) a species of tiny pig off the coast of “New Australia,” which, according to Beth, is “about 30 yards east,” to which Morty adds, “or 300 yards west.”

Boom. We’ve got a meaningful number.

If Morty and Beth are describing the same point, and we know its distance from their point, both east and west, we know the distance around the full sphere, or the circumference. We’re going to assume Morty and Beth were talking about 30 and 300 yards due east and due west, respectively. The full circumference around Tiny Earth? 330 yards.

Now we can crack this nut.

What we’re trying to do is figure out Tiny Earth’s gravitational pull. Here’s how we’re going to do it.

The formula we need is the gravitational field formula:

g = Gm/r²

Where:

g = the gravitational field strength in m/s²

G = the Cavendish/gravitational constant: 6.67259 x 10^-11 N m²/kg²

m = the mass of the planet in kilograms

r = the distance from the center of the planet, equal to the radius of the planet, in meters

Put the values of m and r in for Earth (5.98 x 10²⁴ kg and 6.38 x 10⁶ m, respectively), and you’ll get right around 9.81 m/s², the accepted value for the Earth’s gravitational field strength. That means things fall at a rate of 9.8 meters per second, every second they are falling. Everything on earth falls this fast, and yes, air resistance screws it up.

So how do we get things going for Tiny Earth? Problem solving. What do we have, and what do we need?

We’ve got the circumference of Tiny Earth in yards, and that’s it. We’ll need to calculate everything for the formula above. Let’s start with the radius of Tiny Earth.

Tiny Earth’s Tiny Radius

We have the circumference of Tiny Earth, so we can work backward using the circumference formula to calculate the radius. Before we do that, we need to get our yards into meters. A quick conversion shows that 330 yards is about 302 meters.

The circumference of a sphere is the same as the circumference of a circle, so we’ll use that formula:

circumference = 2πr

Rearrange to solve for r:

r = circumference/2π

r = 302/ 2π

radius = 48.0 meters

Easy. The next part has a couple of steps, and we’ll need this value for the radius.

Share

Tiny Earth’s Tiny Mass

This is a stop sign for a lot of my students when I assign something like this in my physics class. I think the big problem is that the answer to the question is so simple, they completely miss it. We need the mass of Tiny Earth, right? We know the radius of Tiny Earth, and from that we can calculate its volume. Remember – Rick said that these three planets were all at least 90% like Earth. To keep things simple, let’s assume that Tiny Earth is 100% like Earth (we can tweak those numbers later if we want to, but for now, let’s just get the problem working…)

The Earth is a rocky planet with a known density, and Tiny Earth would have the same density. And as we all learned early on in science, density = mass/volume, and Earth’s density is 5520 kg/m³. Aha.

So – what’s the volume of Tiny Earth? We need the formula for the volume of a sphere:

v = 4/3 πr³

Plug in 48.0 for r, cube it, and complete the calculation.

Volume of Tiny Earth = 463,240 m³

Now for mass:

Density = mass/volume

mass = (density)(volume)

mass = 2.6 x 10⁹ kg

And like that, we’re good to go.

Tiny Earth’s Timny Gravity

This part is simple – just plug the values into the gravitational field strength formula up above, and you’re good to go.

I’ll trust you to do the calculation and the appropriate unit cancellation. Be careful – 9 times out of 10, my students will have everything correct in the set-up and then mess something up in the calculation.

g = 7.5 x 10^-5 m/s²

Wow – that’s like…nothing. Seriously — it’s 0.000075 m/s². You’d barely notice a thing is falling.

I mean…the gravitational field strength on the moon is a relatively robust 1.62 m/s².

This would affect everything in our reality – for example, we could easily calculate the escape velocity (how fast you need to move upward in order to escape the gravitational field of Tiny Earth), using the formula:

v_e = √2Gm/r

v_e = √2(6.673 x 10^-11)(2.6×10⁹)/48.0

v_e = 0.084 m/s, or about 8.4 cm per second.

Jumping up would be overkill. That’s waaaay slower than an easy jog (about 3 m/s). If you didn’t stay still, just walking would get you off Tiny Earth.

Just for comparison, the Earth’s escape velocity is 11,184 m/s.

And the weak gravitational field would also affect how quickly things fall. Applying the free-fall formula under these circumstances, we can show just how wonky that tiny bit of gravity would be if you dropped something from 2 meters (a little less than Rick’s height) on Tiny Earth:

The free fall formula:

x = 1/2 g t²

Where:

x = the distance fallen in meters

t = time in seconds

rearranging to solve for time:

t = √2x/g

t = 231 seconds, or about 3.9 minutes

Just for comparison (and using the same formula), on real earth, an object dropped from 2 meters lands about .64 seconds after you drop it.

But…But,…But…They Seemed Okay…

Sure — the only strange thing was the size of the planet. Rick and the family seemed fine otherwise, or, as we’re concerned, as if gravity were just fine on Tiny Earth. How would that work?

Tiny Earth was Tiny Earth, so the size is set. What’s the only way that the gravitational field strength can change? The mass of Tiny Earth has to change. Normal Earth gravity is 9.8 m/s², so what do we have to do to get Tiny Earth’s g value up to that same value? Crank that mass. By how much? Let’s talk math and the formula we used earlier, but this time, we’re solving for mass, so…

g = Gm/r²

9.8 = (6.673 x 10^-11)(m)/(48)²

Rearrange and solve for mass – we find that for the gravity of Tiny Earth to be the same as real Earth’s, the mass will be:

m = 3.39 x 10¹⁴ kg

Okay – so what? What can we do with that?

We can figure out what Tiny Earth was made from. Remember density? If Tiny Earth has the same gravity as Earth, we know what its mass has to be, and its volume hasn’t changed, so we can calculate the density:

D = m/v

D = 3.39 x 10¹⁴/463,247

Density of Tiny Earth (for normal Earth gravity) = 7.3 x 10⁸ kg/m³

That’s basically the same density as a white dwarf star – a star near the end of its life, with roughly the mass of the Sun and the volume of the Earth.

Tiny Earth isn’t very earth-like at all, when it comes down to it.

If you want to tweak this out and play with values that are, say, 92.3% Earth-like, then you’re talking about changing the density, which would affect the mass. If you’re trying to make Tiny Earth work that way, you’re going the wrong direction – a smaller mass will only decrease the gravitational field strength, but give it a shot.

But that’s not quite all – living on Tiny Earth would be its own horror show. Over at xkcd, Kevin Munroe went into depth about what “living” on a tiny earth/rock/asteroid would be like, using The Little Prince as a launching point.

Gravity obeys the inverse-square law, so the farther away you get from the center of the planet, the more the gravitational field shrinks, so as a result, the gravitational field would have one value at your head and another near your feet. And given the pull of gravity on Tiny Earth, this would be significant.

How significant?

Let’s say you’re 5 feet, 9 inches tall (1.75 meters).

So…

• Feet: 48.00 m from the center

• Head: 49.75 m from the center

A mathematical representation of the inverse -square law looks like:

g ∝ 1/r²

Or, the force of gravity decreases by the square of the radius, twice as far from the center as your pal, you feel ¼ as much (twice as far = 2x, 2² = 4). So…

ghead​=9.81(49.7548​)2

ghead​=9.13 m/s2

Or roughly, 0.93g, while your feet are living in 1.00 g.

Sure, it’s only 7% weaker at your head, but that 7% difference is 140,000 times larger than the difference you feel on earth.

What would it feel like?

It wound’t be like you were being torn apart, but it would feel weird. Your circulatory system evolved to work against Earth’s very gentle gravity gradient. On Tiny Earth:

• Blood would tend to pool differently.

• Standing upright might feel strange.

• Jumping could feel unstable.

• Tossing a ball upward would produce visibly different motion than you’re used to.

On Tiny Earth, gravity would be weird however you want to slice it. Your head and feet would experience measurably different gravitational pulls if it has the same gravity as Earth, or, if it had gravity that follows the rules we’re used to, dropped objects would take minutes to hit the ground, and an enthusiastic leap could send you drifting off into space.

In other words, looking at it through the lens of our world’s science, Rick’s replacement Earth isn’t really an Earth at all. It’s a tiny, adorable death trap.

Is looking at Rick and Morty’s science your idea of a good time? I gotchu! I wrote a whole book all about it a few years back — you can get your copy here, or wherever books are sold.

And it all checked out nicely — in an effort to rid himself of his nemesis once and for all, the Leader sent the Hulk back in time, 66 or so million years ago, to the Yucatán region, just in time for the Chicxulub (pronounced “chick-shaloob”) Impactor to hit. The dinosaurs the Hulk was fighting were appropriate for the time period, the location was right, and everything looked good.

Subscribe now

Actually, bad for the Hulk. The asteroid that wiped out the dinosaurs was coming, visible in the sky. The Cretaceous Period, the last act of the Mesozoic Era and the Age of Dinosaurs, was about to end in spectacular fashion.

So here’s how things start off…

Rock Smash Hulk

The Hulk (strongest one there is) is still fighting the dinosaurs he met at the end of the last issue (note: the Leader’s really flexing his intelligence here by pinpointing the time within an hour or two of the asteroid hitting Earth), and then, the impact.

Everything close to the impact site is instantly vaporized. Best research suggests that the rock that hit Earth was between 10 and 15 km across (6–9 miles), with a mass of roughly a trillion metric tons, traveling at about 20 kilometers per second, or roughly 45,000 miles per hour. It was most likely a clumpy mass of carbon-rich rock that originally called a region of our solar system beyond Jupiter home before it came in for a close-up look at Earth. Don’t ignore that speed — moving that fast, it could’ve crossed the United States in 4 minutes. Or, more importantly, when dinosaur eyes registered the flash of impact, the crater was already excavated.

I still love the fact that if you look up “Chixculub Impactor” on Google, the results pop up, an asteroid streaks across your screen, and the screen shakes with the impact.

The force of the asteroid’s impact cannot be overstated. It was so massive and moving so fast that when it struck the Yucatán Peninsula, it vaporized. Quick science lesson: think of it like an ice cube. You can heat an ice cube until it melts, and if you keep adding heat, you can boil the water, turning it into vapor. In a beaker or on your stove, it takes time for the energy to do its job. Now imagine skipping over the whole “solid turns to liquid, and then the liquid warms up” part and putting enough energy into the ice to turn it into a gas in less than a second.

That’s scary. And the asteroid had enough energy to do that and more.

Fun Fact: We know a lot about the impact. For instance, we know that the asteroid came in at a steep angle, probably around 60° relative to the impact surface. This was probably the worst possible angle it could have had. As a result, it blasted up more debris and vaporized more of the site than a shallower angle would have. We also know that the impactor hit during Northern Hemisphere spring, thanks to fossil evidence. This was a particularly bad time, as life was just starting up for the season—eggs were being laid, and trees and plants were flowering and kicking off their annual growth. And if the impact had happened just three hours later, the asteroid would not have struck the shallow sea covering the Yucatán region, but rather the deep Pacific Ocean, and things probably would have gone very differently. And finally, when the leading edge hit the ground, the trailing edge was still about 10 km above the surface - just about the altitude for airlines.

The crater from the impact is 180 kilometers in diameter (110 miles), but again, there’s nothing of the actual asteroid left down there. Just some broken and buckled bedrock that attests to the energy of the impact and its angle.

One of the reasons the impact was so devastating comes from the same adage used in real estate: location, location, location. The impact site was loaded with sulfur-rich bedrock, and much of it vaporized along with the asteroid. This resulted in sulfur compounds (sulfur dioxide, sulfur trioxide, and others), along with carbon compounds (lots of carbon dioxide) and soot, being blasted into the atmosphere.

After getting cooked and regrowing tissue a few times, the Hulk (who somehow survived being near ground zero) leaps himself out of there.

Share

After the Impact

While the Hulk was right to get as far away as he could from the impact site, in reality, it probably didn’t matter much. Earth was hell.

It’s not entirely clear how long the Hulk was jumping around post-impact (“After what feels like an eternity…”), but he wouldn’t have found safety anywhere. In the immediate hours to days after the impact, materials that had been blasted into the upper atmosphere—the ejecta—would be falling back to Earth. As the material fell, it compressed the air beneath it, heating both the air and the material itself (for more on this, check out the article about the Artemis II reentry and the Flash running really fast).

There’s still debate about exactly how hot it got and what that meant for life on Earth, but many dinosaurs were likely broiled to death, and much of Earth’s vegetation burned, releasing even more soot and carbon dioxide. During that time, it would have felt like you were inside a toaster oven, with the sky glowing red as millions of tons of material fell back toward the ground. And fires surrounded you. Extinction Wave #1.

Understandably, it would make the Hulk mad.

Then, things get really bad. After Earth’s temperature setting comes down from “broil,” all of the sulfur compounds and other particulate matter that remain airborne reduce the amount of sunlight reaching the surface, cooling the planet and wiping out even more plants (and, by extension, the herbivores and carnivores that depended on them). The oceans cooled as well, taking out many organisms that had been lucky enough to survive the immediate effects of the impact. All told: Extinction Wave #2.

But despite being dealt one of the worst hands imaginable, life somehow endures. Animals that could burrow, retreat deep enough into the water, or survive as scavengers—and those that were simply too mean to die (crocodiles, I’m looking at you)—eked out an existence and endured.

And for some of those poor creatures, the Hulk finds them.

Fun Fact: That stuff that fell from the sky after the impact—the soot from burning forests, particulates, and even the vapor that once made up the asteroid—settled all over Earth and is still around today. In some locations, if you know where to look, you can spot the line of dark material sandwiched between other layers of rock. This thin band of dark clay, often only a few centimeters thick, is called the K–Pg Boundary. In the rock layers below the K–Pg Boundary, you find fossils of the large non-avian dinosaurs. Above it, none. It’s a bookmark in Earth’s history, a physical reminder of one of the worst days our planet has ever experienced. It’s distinctive because of the combination of elements it contains—particularly iridium, which is rare in Earth’s crust but relatively common in asteroids.

The initial suggestion that the K–Pg Boundary represented an asteroid impact came from physicist Luis Alvarez and his son, geologist Walter Alvarez, in the late 1970s. Based on its composition, they proposed that a roughly 10-km-wide asteroid had struck Earth 66 million years ago. Remarkably, Alvarez and his colleagues advanced the hypothesis before the Chicxulub crater was identified, and later crater research largely confirmed their estimates of the impactor’s size. There is still debate about some of the details and methods because... science.

Subscribe now

Please Don’t Kill Our Ancestors

At some point after all his jumping, the Hulk lands near a dead dinosaur being nibbled on by a group of small mammals. Yes, mammals. They existed alongside dinosaurs right up until the end of the Cretaceous.

You may think the image is showing rats, and that’s what the Hulk calls them, but they are definitely not rats. Rats didn’t arrive on the scene until roughly 3 to 5 million years ago. More likely, what the Hulk sees is a representative visual of several types of mammals that were around at the time, such as:

Protungulatum - early placental mammal

Purgatorius – possibly one of the earliest primate relatives, and

Multituberculates — rodent-like mammals that survived the extinction remarkably well

They were all rodent-like in the sense that they could reproduce quickly, burrow, survive on small energy budgets, and eat almost anything.

Including a dead dinosaur.

In fact, if you let the evolutionary tree grow from small mammals like the ones the Hulk spots—mammals that are about to become very important to our story—it might look something like this:

66 million years ago
→ small mammal survivor

60 million years ago
→ early placental mammals

55–60 million years ago
→ primate lineage emerges

40 million years ago
→ early anthropoid primates

20–25 million years ago
→ apes

6–7 million years ago
→ last common ancestor of humans and chimpanzees

300,000 years ago
→ Homo sapiens. Yay!

The big idea here is that, with the non-avian dinosaurs out of the way (and the theropods doing their own thing, thanks guys), mammals were able to explode into thousands of different forms, each finding a niche in the biosphere left vacant by the impact.

It just so happens that the Hulk (still angry and looking to smash) showed up near a group that was incredibly important to the branch that would eventually lead to us.

Seeing our distant ancestors, the Hulk…

…smashes them. Great.

You kind of want to side with the Leader here, don’t you?

If Not Us, Then Who?

In the present, immediately after the smashing of our early ancestors by the Hulk, the Leader feels a temporal wave…one of a variety of hand-wavey time-travel conventions in science fiction that suggest changes in the deep past are only reflected in the present when they serve the plot. Quickly realizing that the Hulk somehow survived the asteroid impact, he jumps back 66 million years to make things right.

But wait— let’s just say, for a second, that he didn’t get to the time platform in…time, and the present reshaped itself around the past where the Hulk smashed the early placental mammals that were our ancient ancestors. Ignoring the idea that, if the Hulk stopped humans from existing, he would have stopped himself from existing and therefore wouldn’t have been around to smash the small ancestor mammals in the first place (I know, big ask)...what would the “present” be like?

So, take a peek outside the Leader’s base in the “present,” where the Hulk has destroyed all chance of primates evolving. What would you see?

Birds. Lots and lots of birds.

Smaller theropods, small feathered dinosaurs, were on the rise before the impact and survived after. Even the Leader pointed it out, saying later that the impact wiped out all “non-avian dinosaurs.” With mammals around as evolutionary competition, those surviving theropods evolved into the more than 10,000 species of birds known today. Without mammals competing for resources and ecological niches? Oh, they’d run the joint.

The extinction left behind a huge number of vacant ecological roles, and evolution hates empty real estate. Run down the list — the impactor took out:

• large herbivores

• small insectivores

• mid-sized predators

• scavengers

• seed eaters

• tree dwellers

• ocean hunters

In our timeline, mammals exploded into those niches. But if the Hulk somehow removes the mammalian lineage that eventually gives rise to primates, rodents, carnivores, whales, bats, and everything else, those niches don’t remain empty. They get filled by dinosaurs. Theropods.

Earth is Birdworld.

Research suggests that, by the end of the Cretaceous, some theropods were demonstrating at least modest intelligence, complex social behavior, and possibly even cooperative hunting. That requires information transfer, communication, and brains capable of handling both.

So yeah, after the impact’s aftermath, birds were ready to fly.

They were already:

• warm-blooded

• intelligent

• highly mobile

• diverse

• surviving the extinction successfully

Give them 66 million years, and the descendants of those ancient theropods would almost certainly diversify into forms we can barely imagine.

Think less “sparrows” and more:

• crow-equivalents filling primate niches

• giant flightless omnivores filling bear niches

• predatory terrestrial birds filling wolf niches

• highly manipulative beaks (maybe hand analogs) and feet evolving for tool use

After all that time to evolve, a corvid-like lineage becomes a very plausible candidate for producing human-level intelligence.

Okay—maybe the mammals Hulk killed weren’t our direct ancestors, but killing them caused a temporal storm anyway. Other contenders for winning the evolutionary lottery would include intelligent descendants of rodents, raccoon-like mammals, snakes and lizards, crocodilians, marsupials, or something we simply can’t imagine.

Evolution wasn’t and isn’t “pointed” towards humans as the end result. Large brains have evolved independently multiple times, so if you remove the branch that eventually sprouts humans, there are other contenders waiting for their shot.

But birds are probably the safest bet.

Which Marvel Earth is Bird-Earth again? I mean, if we go all TVA on this, that branch might still exist before it gets pruned back into the Sacred Timeline. I mean, Captain America is a bald eagle. Falcon is still a falcon (duh). Iron Man becomes a highly evolved crow in powered armor—Iron Corvid. Reed Richards is a parrot with frightening reserves of theoretical intelligence. Spider-Man is a starling.

Oh, it goes on and on.

Side Note: If going down these lines of thought makes your brain hungry for more, you’ve got to check out Adrian Tchikovsky’s Children of Time series (Children of Time, Children of Ruin, and Children of Memory), all of which explore civilizations where species other than primates took the lead.

The Leader and Family Trees

Arriving in the past (again, with uncanny precision), the Leader protects our early post-impact ancestors by tricking the Hulk and sending him into the next trap.

Yeah. “Hello, great-to-the-nth-degree grandmother.”

Strictly speaking, that’s not how evolution works. Sixty-six million years ago, individual family trees blur into populations. That little survivor isn’t a single grandmother waiting at the root of humanity’s family tree. She’s part of an entire population of survivors from which all later humans eventually emerge.

But for comic-book dialogue, it’s close enough.

And honestly, “Hello, member of my ancestral breeding population” doesn’t have quite the same ring to it.

As for the “nth” part, that can actually be estimated.

Sixty-six million years divided by roughly 25 years per generation means that, between that small mammal and the Leader, there would have been about 2.6 million generations. So, the technically ridiculous version would be:

“Hello, my 2,600,000th-great-grandmother.”

And even that probably understates the number, because early mammals reproduced much faster than humans do. If you account for shorter generation times throughout much of mammalian history, the true figure might be closer to five to ten million generations.

And if we want closer relatives for comparison:

Lucy-era hominins: ~150,000 generations ago
Human–chimp common ancestor: ~250,000–350,000 generations ago

So the Leader’s “great-to-the-nth-degree grandmother” is way, way deeper than Lucy. Lucy is ancient to us, but compared to those asteroid survivors, she’s practically family gossip.

Next Time…

We’ve wrung all the science out of this issue, so where are we heading next? In the final pages, the Leader uses the time platform as a space platform as well (no complaints here) and shoots Hulk to the black hole in the center of the Milky Way, Sagittarius-A*.

We’ll be back soon with a look inside, and trust us…

There will be spaghettification.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four.

In the Wonder Woman film (2017), Dr. Poison has everything going for her as a classic villain. She’s broken. She’s creepy. She’s troubled. She’s brilliant. And she knows her science.

Apparently in the thrall of General Ludendorff, Dr. Poison – Isabel Maru, played by Elena Anaya - was responsible for developing, well…poison weapons for the German army in World War I, including a hydrogen-based gas (small molecular-sized particles could slip through filters) that could penetrate gas masks (and crack their glass too).

Subscribe now

As for where the character came from, Dr. Poison was Wonder Woman’s first “costumed” villain, appearing in 1942’s Sensation Comics #2. In that appearance, Dr. Poison (created by Marston and Harry Peter) was revealed to be Princess Maru, an Asian Princess tied to both the Yellow Peril and the rising anti-Japanese sentiment in the United States at the time. Since her first appearance, Dr. Poison has been rebooted three additional times in DC Comics, and is currently Marina Maru, leading an organization called…Poison (no, not the ‘80s hair band).

Dr. Poison in the film is frightening enough, but in this case, there’s a real-world analog, someone who has been celebrated and castigated through the years. Our world’s own complex character using science to help and hurt – Fritz Haber, the “Father of Chemical Weapons.”

And also, “the man who killed millions, but saved billions.”

Okay, but before we get into it, was Haber really the inspiration for the original Dr. Poison in 1942?

I mean…(waves hands).

Sensation Comics was originally written by William Moulton Marston, who created Wonder Woman and her initial cast, including Dr. Poison in issue #2. While there is no direct evidence connecting Dr. Poison with Haber, Marston was in college when chemical weapons made their debut.

The Wonder Woman creator was at Harvard from 1915 to 1921, earning a B.A., a law degree, and a PhD. in psychology. He was certainly no stranger to science and almost certainly would’ve heard of the use of chemical weapons by the Germans following their first use in the Second Battle of Ypres in the spring of 1915. The use of the gas was widely reported in papers throughout America, from The New York Times to The Chicago Tribune.

Firsthand accounts of the gas were stuff of nightmares – a sickly looking yellow-green gas rolling across the landscape, turning any vegetation brown and wilted, flowing down into depressions and pits in the ground, ultimately drifting down into the trenches where the Allied soldiers waited.

So does Haber equal Dr. Poison? The lines are conjecture, so… maybe not directly, but Haber and the memory of WWI gas warfare would have been part of the cultural atmosphere Marston inherited (and was probably goosed by the news of Haber’s death in January 1934).

Before we get into our suspected scientist-inspiration, we should note that Dr. Poison hasn’t been left behind in the ‘40s. Along with appearing in 2017’s Wonder Woman film, there have been other (five…six?) iterations of the character over the years thanks to continuity reboots and restarts.

Share

Most recently, Dr. Poison has returned in Absolute Wonder Woman, where she’s a member of Veronica Cale’s Suicide Squad. This time, the character gives more than a passing nod to poison gases - she is a sentient cloud of poison gas.

Her original version from Absolute Wonder Woman #8, designed by Kelly Thompson and Hayden Sherman

The image below is actually Poison’s second suit, after she…colorfully complained to Cale that the first one, which was bulkier, didn’t allow her to do delicate work.

So, back to Fritz Haber, our maybe kinda real-life inspiration for Doctor Poison.

If you can maybe remember him from a chemistry class or a YouTube video, you may already have a sense for who Haber is. But if we’re being honest, Haber, like Wonder Woman’s Dr. Poison, is a complex individual who resists the broad-brushing of turning him into a simple villain.

Fritz Haber is often cast as a lone German mad scientist in stories about chemical weapons used in World War I, but that’s not quite accurate. Chemistry was the hot science in the early 20^th century. In many ways, World War I was an opportunity for the leading industrial nations to showcase their technologies to the rest of the world. Despite the Hague Convention of 1899 and 1907, which prohibited the use of asphyxiating gas projectiles in war, France used tear gas/irritant agents on the Germans in 1914. Once the Germans introduced gases on the battlefield, the Allies answered with gases of their own. Lost to most history and chemistry texts, in fact, is Haber’s rivalry with the French chemist Victor Grignard, who also studied gas weapons. No, this wasn’t a case of Haber secretly toiling and developing chemical weapons for war. The whole world was headed in that direction. Haber just got there first.

But before we expose his dark side, let’s make one thing clear – Haber was a brilliant chemist. Before he became known for his work with chemical agents, Haber, in collaboration with Carl Bosch, invented the Haber-Bosch process, a means to literally pull nitrogen out of the air (with the use of a metal catalyst under high temperatures and pressures)

Chemistry students know the Haber-Bosch equation well – it’s usually the go-to equation to explain Le Chatelier’s Principle:

N₂ + H₂ -> 2NH₃

The ammonia (NH₃) is then used to produce fertilizer, which, in Haber’s time, was desperately needed to help feed the world’s rapidly growing population. The process is still used today and is often pointed to as one of the main factors that has allowed the Earth’s population to grow to over 7 billion. For their work on a process that benefits all humanity, Haber won the Nobel Prize in 1928 for ammonia synthesis, while Bosch won in 1931 for high-pressure chemical methods. Haber’s win in 1918 was…controversial to say the least, with the Nobel committee explaining that they only considered his work that benefited agriculture, rather than his wartime activities.

However, pulling all that nitrogen in the air and making it useful drew the attention of the German Army, which needed it for nitrogen-based explosives during the Great War.

When the Great War came, Haber saw himself as a German first and a chemist second (in opposition to his friend, Albert Einstein, who was critical of Germany), and told the German government he would do whatever his country needed to help in the war effort.

Like Dr. Poison, Haber was not regarded as a traditional war hero by the German military leadership. These were generals and soldiers of the Victorian Era – gentlemen first, soldiers second. Haber’s ideas of killing the enemy with gas were seen as “unchivalrous” and “repulsive.” But Haber was steadfast, insisting that the gas would be a means of reducing German casualties (while increasing those of the Allies) and of ending the war faster (with Germany on top). In the end, Haber’s plans for chlorine gas were a means to an end, and the generals finally took Haber’s advice of “using chemical warfare with conviction.”

With the military finally behind him, Haber threw himself and his lab at the Kaiser Wilhelm Institute for Physical Chemistry into the business of making a poison gas for the troops. By April of 1915, Haber had his perfect concoction and was on the front lines at Ypres, Belgium. There, he waited for weeks until the winds were just right, and on April 22nd, he released over 168 tons of the gas from canisters, which exploited the wording and was still plainly against the spirit of the Hague Convention, which outlawed gas projectiles whose sole purpose was spreading asphyxiating/deleterious gases.

Denser than air, the gas drifted like a low, yellow wall towards the French trenches. Hundreds to thousands (depending upon your source) of French and Algerian soldiers died from exposure. While the gas use did not lead to an immediate victory for the Germans, it emboldened Haber and the German High Command to view gas weapons in a favorable light.

Haber oversaw another attack at Ypres, this time on Canadian troops, and by May 2^nd, had been promoted to a uniform-wearing Captain and was headed home to Berlin for a party in his honor. He was living a celebrated existence at this point – a party on the 2^nd, and then on May 3^rd, he was headed to the Eastern front to oversee a gas attack on the Russians.

Haber’s wife, Clara Immerwahr (a brilliant chemist in her own right, and the first German woman to earn a PhD in chemistry), long disagreed with her husband’s militarization of science and development of chemical weapons, and on the night of the party, shot herself in the chest with his service revolver (she didn’t die immediately and was found by their 12-year-old son, Hermann, but Fritz reportedly slept through the shooting).

Haber was so not broken up by his wife’s death that he didn’t bother changing his plans and headed out to the Eastern Front the next day – though he later said Clara’s face and words still haunted him.

But whether or not his wife’s ghost haunted him, it didn’t slow down his work.

After the debut of Haber’s chlorine gas, the chemist went on to oversee the development of phosgene gas (COCl₂) and mustard gas ((ClCH₂CH₂)₂S). Each of the three gases used in World War I is horrible, and while both German and Allied armies rapidly developed gas mask technology to minimize the effects of the gases, there were approximately 1.3 million gas-related casualties and around 91,000 deaths from poison gases in World War I between their debut at Ypres in 1915 and the end of the war in November of 1918.

Strictly from the chlorine gas side of things, inhalation of the gas is a horrible way to go, thanks to the reaction that happens in the lungs that produces both hydrochloric acid and hypoclorous acid:

Cl₂ + H₂O <-> HCl + HOCl

The water on the reactant (left) side would be found in the lungs or on the surface of the eyes. The gas could blind those without protection, while in the lungs, the alveoli would be damaged or scarred, reducing the ability to absorb oxygen – if you were lucky. If you were unlucky, exposure to hydrochloric acid would cause lung cells to rupture (lyse), releasing their contents. Fluid-filled lungs would literally lead to drowning on dry land.

On April 26^th, 1915, The New York Times reported on the battle:

“Some (soldiers) got away in time, but many, alas, not understanding the new danger, were not so fortunate and were overcome by the fumes and died poisoned. Among those who escaped, nearly all cough up blood, the chlorine attacking the mucous membranes. The dead were turned black at once … (The Germans) made no prisoners. Whenever they saw a soldier whom the fumes had not quite killed they snatched away his rifle … and advised him to lie down to die better.”

Mustard gas and phosgene were, reportedly, even worse, sometimes delaying their deadly effects until after the battle was over. Haber also worked on a gas blend called maskenbrecher or “mask breaker” – an agent that would be small enough to get through the filters of a gas mask and cause a violent reaction from sneezing to vomiting, forcing soldiers to remove their gas masks, and then be exposed to the other, deadlier gases from which their masks were protecting them. Hey - what was that gas Dr. Poison was working on again?

Following World War I, Haber was designated a war criminal by the Allied Powers, but, like Dr. Poison in Wonder Woman, he escaped capture and prosecution, fleeing to Switzerland in 1919. His name was later removed from the list of wanted war criminals, and he returned to postwar Germany a hero.

During these postwar years, Haber continued his research into poisonous gases, in direct opposition to the Treaty of Versailles. Part of the research into poisonous gases led to the development of the pesticide Zyklon A in the 1920s. Another Haber project in the years of reparations being paid by Germany – he proposed that he could extract gold from seawater.

He wasn’t wrong about gold in seawater. There’s a little bit of everything in there. But Haber’s methods were not up to the challenge, and ultimately, his plans bore no fruit.

While he was initially seen as a favored son in his beloved Germany, the postwar years became difficult for Haber as the National Socialist Party rose to power. Haber’s Jewish ancestry, long known but previously overlooked because of his conversion to Christianity (1924) and patriotic service to Germany, suddenly became impossible to ignore under Nazi racial laws, effectively ending his scientific career.

Doors that were once thrown wide for him were firmly closed. Haber fled his beloved Germany for England in 1933, but his work with chemical weapons kept him from finding a home there. Haber wandered Europe for some time, ultimately dying of a heart attack in a Swiss hotel in January of 1934.

In a cruel twist of fate, or what some might see as karma, Haber had one final role to play in the story of poison gas.

Now, to be clear, Haber did not invent Zyklon B. That pesticide was developed by other German chemists in the 1920s. But it emerged from the same German chemical industry and scientific world that Haber had helped build and champion throughout his career.

Subscribe now

Years later, the Nazis would repurpose Zyklon B for something far darker than pest control. The gas became one of the primary tools of mass murder during the Holocaust, killing millions of people, including countless Jews.

And that’s where the story takes one final, bitter turn.

Haber had spent much of his life trying to prove he was German. He converted from Judaism to Christianity. He devoted his scientific genius to Germany’s war effort. He considered himself a patriot first and foremost.

It wasn’t enough.

The Nazis saw only his Jewish ancestry. He was forced from the country he loved, stripped of the place he had spent a lifetime earning. Worse still, likely, some of his own relatives would later become victims of the regime.

History rarely gives us neat endings. But it is difficult to imagine a more tragic irony than this: a man who helped pioneer chemical warfare, who dedicated his life to Germany, ultimately rejected by that same nation while a poison associated with the chemical establishment he helped create was turned against his own people.

A complex man during his lifetime, Haber’s legacy is equally complex. Some estimates suggest that half the world’s population would not be here if not for the Haber-Bosch process, which enabled the cheap, easy production of fertilizers in bulk. Conversely, the descendants of the victims of Haber’s gas attacks (including those killed by Zyklon B) are not here.

Real-life “villains” are indeed complex characters.

More:

A Brief Biography of Fritz Haber (1868 - 1934) (pdf)

Fritz Haber’s Experiments in Life and Death

Organisation for the Prohibition of Chemical Weapons

Chemical and Engineering News: 100 Years of Chemical Weapons

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

The Milky Way is enormous.

The neighborhood we’ll be visiting today? Not so much.

Well, relatively.

On the scale of the Solar System, the journey Ryland Grace undertook in Project Hail Mary was almost unimaginable. Sixteen light-years is such a ridiculous distance that our brains quietly file it under “basically infinite” and move on.

But that’s only if you’re thinking on Solar System scales.

Zoom out - way out.

Far enough that the entire Solar System disappears into a single pixel and the Sun becomes just another star among hundreds of billions.

From that perspective, Grace’s voyage wasn’t a trek across the galaxy.

It was a trip across the neighborhood.

In fact, the three systems we’ll be visiting today - the Sun, Tau Ceti, and Erid are so close together that, as far as the Milky Way is concerned, they’re on the same street. (If you zoom out to the scale of the observable universe, they really are in the same place. But that’s a different article.)

Today, we’ll travel from Earth to Tau Ceti and then onward to Erid, covering a total of about sixteen light-years without ever leaving the same galactic cul-de-sac.

Before we go, though, let’s make sure we’re all speaking the same language.

Subscribe now

Terms and Conditions that Will Apply

Distance

On Earth, we measure distances in miles (if you’re in one of the few countries still clinging to Imperial units) or kilometers.

Just in case high school science was a long time ago, a kilometer is 1,000 meters, or about 0.62 miles.

That’s Earth-scale thinking. Astronomers gave up on that nonsense a long time ago.

The problem is that space is big. Really big. Distances that seem enormous on Earth become inconveniently small once you leave it.

For travel within a solar system, astronomers use the Astronomical Unit (AU): the average distance between Earth and the Sun.

One AU is about 93 million miles (150 million kilometers).

Using that scale:

• Earth orbits at 1 AU

• Jupiter orbits at 5.2 AU

• Neptune orbits at about 30 AU

For most of the Solar System, the AU is a perfectly useful yardstick. But once you start traveling between stars, even the AU starts feeling a little cramped.

That’s where the light-year comes in.

Despite the name, a light-year is a measure of distance, not time. It’s simply the distance light travels in one year.

One light-year equals:

• 63,241 AU

• 5.88 trillion miles

• 9.46 trillion kilometers

Which sounds enormous until you realize that the entire journey of Project Hail Mary takes place across only a handful of them.

Side Note: Parsecs

At some point, someone will ask why we’re using light-years instead of parsecs. Fair question.

A parsec is another unit of distance used by astronomers. One parsec is equal to about 3.26 light-years.

Unlike a light-year, which is based on how far light travels in a year, a parsec is a unit of distance derived from geometry. Specifically, it’s the distance at which 1 AU would appear to shift by one arcsecond against the background stars as Earth moves around the Sun.

If that sentence made your eyes glaze over, don’t worry. Mine too, and I teach this stuff. The important thing to know is that parsecs are incredibly useful for astronomers because they’re tied directly to how we measure distances to nearby stars.

The important thing to know for this article is that they’re annoying. Not because they’re bad. They’re perfectly good units.

But if I tell you that Tau Ceti is about 3.65 parsecs away and Erid is about 4.9 parsecs away, most people’s brains immediately respond with, “Cool. Is that close?”

If I tell you they’re about 12 and 16 light-years away, respectively, at least the unit itself provides a hint that we’re talking about really large distances.

Astronomers may grumble. They’ll survive.

As for the whole “parsecs in Star Wars” debate, we’re not opening that airlock today.

For the rest of this trip, we’ll mostly speak in AUs when we’re inside a solar system and light-years when we’re traveling between them.

The simplest version? Think of AUs as city blocks, and light-years as the distance between towns.

One final note before we leave Distance behind: If you draw lines between Earth, Tau Ceti, and Erid, you don’t get a straight line. You get a triangle.

Earth sits at one corner. Tau Ceti sits about 11.9 light-years away. Erid sits about 16.3 light-years away. The surprising part is the third side.

Tau Ceti and Erid are only about 10 light-years apart.

That’s still an absurd distance by human standards. But on a galactic scale, it’s another reminder that these systems are neighbors.

Again, if the Milky Way were a city, the Sun, Tau Ceti, and Erid wouldn’t be in different states.

They’d be on the same street.

Just for one final reference, and to drive home the point that Erid and Tau Ceti are our neighbors, the center of the galaxy is 26,000 light-years away, while one of our nearby galaxies, the Andromeda Galaxy, is 2.5 million light-years away. Yeah, given that, we can look at Tau Ceti or Erid and see if someone left a light on in the window.

Share

Types of Stars

Before we start hopping between solar systems, we need to talk about stars.

Not all stars are the same.

Some are larger, hotter, brighter, and burn through their fuel like a college freshman discovering energy drinks. Others are smaller, cooler, dimmer, and can keep shining for tens or even hundreds of billions of years. As a general rule, the cooler you burn, the longer you live.

Astronomers classify stars by their temperature and color using a system that ranges from hot blue stars to cool red stars. There are considerably more details than that, but for this trip, we only need to concern ourselves with three stars.

The Sun

Our Sun is a G-type main-sequence star.

It’s the standard unit for this part of the trip: 1 solar mass, 1 solar radius, 1 solar luminosity.

Convenient. Almost suspiciously convenient. Like we live next to the thing or something.

The Sun has been steadily converting hydrogen into helium for about 4.6 billion years. It is bright enough to keep Earth warm, quiet enough not to sterilize it, and massive enough to provide the gravity that holds the entire Solar System together.

When astronomers talk about another star’s mass, radius, or brightness, they often compare it to the Sun.

Think of the Sun as the Holiday Inn of stars. Not the biggest. Not the fanciest. But clean, reliable, and familiar enough that we use it as the baseline for comparison.

Tau Ceti

Tau Ceti is also a G-type main-sequence star, making it one of the Sun’s closest cousins in the neighborhood.

It is smaller and dimmer than our Sun:

• about 0.78 solar masses

• about 0.79 solar radii

• roughly 0.5 solar luminosities

In plain English: Tau Ceti has about 78% of the Sun’s mass, about 79% of its radius, and gives off about half as much energy (even before its Astrophage infection). So yes, it is Sun-like.

But “Sun-like” does not mean “basically the Sun with a different nametag.”

If you somehow swapped the Sun for Tau Ceti tomorrow, Earth would get colder. Not “instantly frozen death planet” colder, but colder enough that everyone would notice, especially the plants, the oceans, and everyone who already complains when the thermostat drops two degrees.

Tau Ceti is familiar enough to be useful and different enough to matter.

Which is exactly why astronomers care about it. It’s close enough to study, familiar enough to compare, and weird enough to keep things interesting, which we’ll talk about coming up.

Erid (40 Eridani A)

Erid is different.

The star Rocky calls home (which Grace eventually names “Erid”) is known to astronomers as 40 Eridani A. It is a K-type orange dwarf: cooler, dimmer, and longer-lived than the Sun. The “A” in its name is to keep track of it - 40 Eridani is a triple-star system, so there’s 40 Eridani A, B and C.

Side Note: No, we’re not going to lean into the 3-Body Problem here, either. This is Project Hail Mary. Focus.

Erid’s numbers are close to Tau Ceti’s in mass and size, but not in color or stellar personality:

• about 0.8–0.85 solar masses

• about 0.8 solar radii

• roughly 0.4–0.5 solar luminosities

That means any potentially habitable planet orbiting Erid needs to orbit closer to Erid than Earth does to the Sun to receive comparable energy if we’re talking about human life. Which we’re not.

The payoff for Erid’s lower energy output is longevity.

Stars like the Sun live for roughly ten billion years. K-type stars like Erid can remain stable for several times longer. That matters because life does not care whether a star impresses us.

Life cares about time.

A stable environment that lasts for tens of billions of years gives evolution an awful lot of opportunities to try new things.

And as we’ll soon discover, these three stars host very different neighborhoods.

Habitability and Amenities

Before we dig in, let’s recognize our bias.

When astronomers talk about a planet being “habitable,” they’re usually talking about conditions that could support life as we know it. That sounds narrow because it is.

The problem isn’t a lack of imagination. The problem is a lack of data. We currently have exactly one example of a life-bearing world. Earth. Every definition of habitability we use is built from that single sample.

Liquid water. Moderate temperatures. A stable energy source. An atmosphere thick enough to be useful and thin enough not to crush you. These aren’t necessarily the universal requirements for life.

They’re the requirements shared by every living thing we’ve ever met.

This distinction will become important later.

Our Solar System

If you’ve ever looked at an astronomy diagram and wondered why every solar system seems to be compared to ours, the answer is simple:

It’s the only one we’ve got.

The Sun is our home star, our calibration standard, and the source of nearly every assumption we make about how solar systems are supposed to work. This is both reasonable and dangerous.

Reasonable because Earth is the only life-bearing world we’ve ever found.

Dangerous because Earth is the only life-bearing world we’ve ever found.

Side Note: The Goldilocks Zone

The Sun’s habitable zone is the region where temperatures could allow liquid water to exist on a planet’s surface. Not too hot, not too cold, just right.

For our Sun, Earth sits comfortably inside this zone at 1 AU (our reference point for basically everything). Venus is a little too close and has paid the price by becoming a pressure cooker wrapped in sulfuric acid clouds. Mars sits near the outer edge and appears to have spent much of its history arguing with itself about whether it wanted to remain habitable.

Being in the Goldilocks Zone does not guarantee habitability.

It simply means the thermostat is set correctly.

The rest of the house still has to be worked on.

Local Attractions

Our Solar System offers a surprisingly diverse set of destinations: inner, rocky planets that include Earth (the only place known to support life), and then the gas giants, each with enough moons to qualify as miniature solar systems in their own right.

Debris and Other Hazards

The Solar System is remarkably tidy. That’s not because there isn’t debris.

There is.

The Asteroid Belt between Mars and Jupiter contains millions of rocky bodies. Beyond Neptune lies the Kuiper Belt, home to Pluto and countless icy objects. Far beyond that lurks the Oort Cloud, a vast spherical reservoir of comets that extends almost halfway to the nearest stars.

But compared to what we’re about to see, our Solar System looks positively well-maintained.

The neighborhood association has clearly been doing its job.

The Tau Ceti System

If the Solar System is the neighborhood’s well-maintained reference property, Tau Ceti is the house down the street where the yard has gotten a little out of hand.

At first glance, Tau Ceti looks reassuringly familiar. The star itself is one of the Sun’s closest cousins: slightly smaller, slightly dimmer, and a bit older. If you were somehow able to stand on a planet orbiting Tau Ceti and look up, the star in the sky would not strike you as wildly alien. You’d recognize it as a star much like our own.

The similarities are one reason astronomers have spent so much time studying it. If the Sun and Tau Ceti started with broadly similar ingredients, comparing the two systems gives us a chance to understand how solar systems can evolve in different directions.

Local Attractions

Current evidence suggests that Tau Ceti hosts between 3 and 5 planets, including several super-Earth candidates. As with many exoplanet discoveries, we don’t see these planets directly. Instead, we watch Tau Ceti wobble slightly as unseen worlds tug on it with their gravity.

This means the exact planetary census around Tau Ceti remains a work in progress. As instruments improve and additional observations accumulate, the details continue to be refined. That’s not astronomers being indecisive. It’s astronomers doing exactly what they’re supposed to do when new evidence arrives.

Some of the planets may lie within or near the system’s habitable zone. Whether any of them are actually habitable is a different question entirely.

Debris and Other Hazards

The biggest difference between the Solar System and Tau Ceti isn’t the planets.

It’s the leftovers.

Surrounding Tau Ceti is a massive debris disk containing far more material than we find in our own Solar System. Depending on which estimates you use, the system may contain roughly ten times as much cometary and asteroidal material as ours.

That’s a lot of leftover construction debris.

The implication is fairly straightforward. If planets are orbiting Tau Ceti, they are likely sharing the neighborhood with considerably more asteroids and comets than Earth does. Over long periods, that could mean more impacts, more disruption, and fewer opportunities for a planet’s surface environment to remain stable for billions of years.

That doesn’t make life impossible. Life has proven remarkably stubborn here on Earth. It does suggest, however, that a habitable-zone planet around Tau Ceti may have a more eventful history than our own.

Tau Ceti feels familiar enough to be recognizable, but different enough to remind us that solar systems are not manufactured from a standard template.

The 40 Eridani System

While Tau Ceti is one of the Sun’s closest cousins, 40 Eridani A belongs to a somewhat more complicated family.

As mentioned earlier, 40 Eridani is not a solitary star. It is part of a triple-star system. The primary star, 40 Eridani A, is an orange dwarf. Orbiting far away are two stellar companions: 40 Eridani B, a white dwarf, and 40 Eridani C, a red dwarf.

That’s already enough to make the system interesting.

One member of the family is still in the prime of its life (A). Another has reached stellar retirement and shed its outer layers (B). The third is a small, efficient star that may continue shining long after the others are gone (C).

Local Attractions

The main attraction here is the star itself.

As an orange dwarf, 40 Eridani A occupies a sweet spot that has attracted increasing attention from astronomers over the last few decades. It is smaller and dimmer than the Sun, but not dramatically so. A planet receiving Earth-like levels of energy would need to orbit somewhat closer to the star than Earth does to the Sun, but not so close that it would face some of the challenges associated with smaller red dwarf stars.

Stars like 40 Eridani A burn their fuel slowly.

Very slowly.

Current models suggest that orange dwarfs can remain stable for tens of billions of years—long enough that the Sun will be a memory before they’re done. And potentially long enough for biological and geological processes to play out over extraordinary stretches of time.

When astronomers talk about promising stars for long-term habitability, orange dwarfs frequently find themselves near the top of the list.

Exoplanet searches around 40 Eridani A have produced intriguing but inconclusive results, with some research suggesting a single planet closer to the star than Mercury is to our Sun, far inside the Sun’s habitable zone.

Side Note: Erid and Science Fiction

Writers seem to look at 40 Eridani A and have the same reaction astronomers do: ‘There’s probably something interesting there.’

Andy Weir wasn’t the first to place a planet that supports life around the star. In Star Trek, the star is home to the planet Vulcan, while in the Dune universe, the fourth planet in the star’s system is Richese, home to a technologically advanced culture.

Debris and Other Hazards

While exoplanets have not yet been confirmed for 40 Eridani A, neither has a massive debris disk surrounding the star. If such a structure exists, it appears to be far less prominent than the one that dominates Tau Ceti’s outer regions.

For anyone hoping for long-term planetary stability, that’s good news.

Large debris disks can act as reservoirs of comets and asteroids, increasing the likelihood of impacts over long periods. Without evidence for a substantial disk, 40 Eridani A appears, at least from our current vantage point, to be a comparatively orderly environment.

Of course, astronomy has a habit of humbling anyone who becomes too confident. Future observations may reveal additional surprises.

For now, however, 40 Eridani stands out not because of what surrounds it, but because of what the star itself offers: stability, longevity, and time.

Lots and lots of time.

Subscribe now

Getting There

Project Hail Mary needed, essentially, magic to get Ryland Grace to Tau Ceti, and used the astonishingly convenient properties of Astrophage to do it.

The problem with traveling to nearby stars isn’t speed. The problem is enough speed.

The stars in our little neighborhood are between 12 and 16 light-years away. At the speeds achieved by current spacecraft, the trip would take tens of thousands of years. That’s less “vacation” and more “geological process.”

Astrophage made the problem workable, powering the spacecraft to achieve a speed that is a significant fraction of the speed of light.

And that’s where things get weird. Keeping track of deadlines in Project Hail Mary got a little weird. Earth had only a limited amount of time before environmental catastrophe, the trip to Tau Ceti would take years, and any solution would then need years more to make its way back home.

Huh?

It’s workable, but you have to invite Einstein to your party.

Okay - light touch.

Travel Time and Time Zone Considerations

Keeping things as simple as possible, one of the stranger consequences of Einstein’s theory of relativity is that time itself doesn’t pass at the same rate for everyone.

The faster you move, the more slowly time passes for you compared to people who stay behind. It’s not by much at everyday speeds, but at a substantial fraction of the speed of light, the effect becomes impossible to ignore.

Ryland Grace and the Hail Mary crew don’t just travel a great distance. They travel in a way that causes their clocks to run more slowly than clocks back on Earth. The trip still takes years, just not the same number of years for everyone involved.

If the Hail Mary reached roughly 92% of the speed of light, then, thanks to time dilation, the crew only experienced around 5 years of travel time. Still long enough to require the coma technology, of which Grace turned out to be the only beneficiary. Back on Earth, 13 years would pass.

If you want math, I’ve got math — but be warned: for pretty high-concept physics, the time dilation formula and Lorentz factors are really easy to calculate.

And to travel from Tau Ceti’s region ot space to Erid (picking up Rocky along the way), that’s 10ish light-years, which, at 92% the speed of light, would have taken them around 4.3 years, with another 10-11 years passing on Earth.

Time Zone Information

From Earth’s point of view, the mission takes about 13 years to reach Tau Ceti. Add in the return trip for the Beetles, and you’re looking at roughly a quarter-century between launch and solution.

As for Grace and Rocky, time is different. Everyone on earth is a quarter century older by the end of the story; Grace has aged more slowly. As he explains near the end of the novel, he’s given up trying to figure out how old he is; his best guess is that he’s biologically in his mid-50s, but chronologically, by an earth-based measure, he’s in his early 70s.

Time is not the same at any two points in the universe. It’s not a bug; it’s a feature.

The Neighborhood

At the beginning of this article, I described the Sun, Tau Ceti, and Erid as a galactic cul-de-sac.

That wasn’t entirely a joke.

On human scales, these systems are impossibly far apart. The nearest is nearly twelve light-years away. The farthest is more than sixteen. Even with Astrophage, the trip takes years. Without it, the journey becomes the sort of thing that civilizations attempt rather than that people do.

And yet, on the scale of the Milky Way, these three stars are practically neighbors.

One hosts the only known life-bearing world in the universe, one appears to be surrounded by far more planetary debris than our own Solar System, and one may remain stable for tens of billions of years after the Sun has finished its work.

Three nearby stars.

Three very different stories.

That’s one of the lessons hidden inside Project Hail Mary. The universe doesn’t need to be exotic to be interesting. Sometimes all you have to do is look closely at the neighborhood.

The next time you see Tau Ceti or 40 Eridani A mentioned in a science article, a science fiction novel, or a planetarium show, remember that they aren’t abstract dots on a star chart.

They’re places.

Real stars.

Real systems.

Real neighborhoods orbiting quietly around the same galaxy as our own.

And they’re close enough that, for a brief moment in one very good novel, a science teacher managed to visit them.

Your homework: using your favorite astronomy app, go out and spot Tau Ceti and 40 Eridani A. Both are visible to the naked eye.

Curiosity is what brought me here.

Teaching is what I do with it.

If you’d like to read more about education, classrooms, students, and the craft of teaching, you’ll find those stories in Teacher, Teacher.

This piece was originally published on a previous version of The Science Of and has been recovered from the digital strata. Its lightly edited version is represented here because it’s useful, weird, fascinating, updated, or some combination of the four.

DC Comics’ Fury of Firestorm #2 had a cover with a familiar look to it.

The issue continues the tradition of Leonardo da Vinci’s famous Vitruvian Man sketch appearing on comic book covers.

Vitru-whovian Man?

Subscribe now

While Leonardo put the sketch to paper, he named it after the observations of Marcus Vitruvius Pollio, a Roman architect from the time of Caesar Augustus (ca. 80 - 70 BCE - 15 BCE). Vitrivius’ observations about the proportions of a human being were among the first ever recorded and included many different ratios:

• From the chin to the top of the forehead is 1/10 of the person’s height.

• From the wrist to the tip of the middle finger is also 1/10 of the height

• From the chin to the crown of the head is ⅛ height

• From the bottom of the neck (in line with the tops of the shoulders) is ⅙ height

• Mid-chest to the top of the head is ¼ height

• The length of the foot is ⅙ of the height

• The length of the forearm is ¼ of the height

• The breadth of the chest is ¼ of the height

And, of course, the circle thing. As Vitruvius wrote in Book III of his Ten Books on Architecture,

“For if a man be placed flat on his back, with his hands and feet extended, and a pair of compasses centered at his navel, the fingers and toes of his two hands and feet will touch the circumference of a circle described therefrom. And just as the human body yields a circular outline, so too a square figure may be found from it. For if we measure the distance from the soles of the feet to the top of the head and then apply that measure to the outstretched arms, the breadth will be found to be the same as the height, as in the case of plane surfaces which are perfectly square.”

As a result, Vitruvius’ version looks like this:

Vitruvius himself pointed out that these measurements didn’t originate with him. They came largely from his observations of sculptors and artists of antiquity.

Over the centuries since he put the ideas to paper, Vitruvius’ man was illustrated by countless artists, but da Vinci’s is the one that stands out. No shade-throwing at modern comic book cover artists intended.

LEONARDO’S OG VITRUVIAN MAN

First sketched around 1490 by da Vinci, the work is still debated by scholars over whether it’s worth the title the artist used. Leonardo pointed out (and his illustration reflects this) that Vitruvius’ square and circle cannot share the same center.

At least with humans as we know them.

As a result, Leonardo’s figure is centered at the groin rather than the navel, pulling the square down so it doesn’t rest inside the circle. Along with centering the figure differently, Leonardo showed the figure with hands raised to the top of its head, then superimposed the image on top of the other. The result is a figure with 16 different poses that owes as much, if not more, to Leonardo as to Vitruvius.

Also a scientist (and honestly one of history’s most aggressively curious people), Leonardo based his Vitruvian Man on data. He took meticulous measurements of Italian models and let that inform his final result. One cool note on Leonardo’s version is that the text at the top and bottom is in his iconic “mirror writing.” It’s written backward on the page but can be read normally by viewing the text’s reflection in a mirror.

While based on the work of the ancient architect, Leonardo’s Vitruvian Man was a radical statement for his time, one of the countless thought-bombs of the Renaissance. The image put humanity at the center of two perfect shapes: the circle and the square. Instead of being passive observers of the universe, people could understand it, measure it, and perhaps even shape it. In line with Humanist ideals of the age, Leonardo’s work shows that man — in body, mind, and soul — is the center of the universe.

On that last one, perhaps HBO’s Westworld employs the Vitruvian Man motif the best. In the series, the robotic hosts produced by Delos, first to populate the park and then in later seasons to take over the earth, are meant to be perfected versions of their human “ancestors.” What better way to show them as perfect than to put them in a pose tied to the ideal human proportions?

Share

WHY DOES THIS KEEP SHOWING UP?

Art is hard, and established proportions are a quick cheat for drawing people?

Okay - that’s oversimplifying, but the core is there.

Lessons on drawing the human body (and many other animals) rest on proportions. Vitruvius’ list of proportions in Ten Books on Architecture documents only some of the proportions that artists and other observers have realized over the centuries. For example, the pelvis’s width is the head’s height plus one-third of the face. The width of the foot is one-half the height of the head. The list goes on and on, most often expressing the human form in terms of the head as a unit of measurement.

It’s also eye-catching on the stands, amid a sea of other covers, blending into a wall of color. It pops, even with the familiarity that it carries. It’s also a way to produce a character reference pose and can suggest meaning for the story inside. In Flashpoint Beyond #4, for instance, Thomas Wayne is hunting the Clockwork Killer, so a clockwork theme informs the interior. While there is no iconic square with Batman in the image, the character is a natural for a Vitruvian homage, given Wayne’s obsession with physical and mental perfection.

As for other comics, how about a quick gallery...

Galactus? we’ve got Gatlactus.

Big coffee table books about DC superhero anatomy? Sure

Wonder Woman? Of course (issue #604, by the way)…

And that’s just getting started…

Subscribe now

Doctor Doom? If anyone would voluntarily pose as the ideal human form, it would be Doctor Doom.

Flash has two and counting…

Love it when science-based characters get a shot at homaging da Vinci…

And then of course, Goofy…

And that’s just a start. If you’re looking for a theme to your comics collection, there are worse.

Make Vitruvian Man a character and put him inside a comic? Sure...been there. And the results were...troubling. The character “Vitruvian Man” (Piero Rosci) showed up in DC Comics’ relaunched Stormwatch series in issue #9 by Peter Milligan and Miguel Sepulveda. Rosci had been changed by a former incarnation of Stormwatch, based on da Vinci’s drawing. Yeah.