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A Biophysicist Explains How Ant-Man Could Kill Thanos From Inside His Butt

If this isn't how 'Avengers: Endgame' ends, at least we got an MIT scientist to talk about Thanos' rectal tolerance

The theory takes “end” game to a whole new level.

Avengers: Endgame, the latest entry in the multibillion-dollar Marvel franchise, is out April 26, and fans are clamoring to know how the merry group of superheroes will possibly beat Thanos, the strongest force in the universe.

There are a few theories floating around the internet, but by far the most popular one is this: Ant-Man, who has the power to get really small whenever he wants, will jump into Thanos’ butthole and expand back to normal size, destroying the supervillain. It’s a clear-cut solution to a complex problem, and the fans are here for it.

The idea was originally floated a year ago by @filmgloss on Twitter:

From there it bounced around. Ant-Man actor Paul Rudd responded to the theory; people debated it on Reddit. But it really gained traction when Redditor u/dregnous brought the scene to life last week:

If this is what you want, then this is what you get. from funny

Right? Brilliant.

Since then, the theory gained so much momentum that Thanos himself, Josh Brolin, posted, uh, this:

Yes, we’re well aware that our laws of physics don’t apply to the Marvel Cinematic Universe. Yes, we’re well aware that death by anus explosion is most likely not the way Thanos will be defeated in Avengers: Endgame. Yes, we still reached out to a biophysicist at MIT to see how this could actually happen.


Alex Klotz is a scientist at MIT. He studies, among other things, “DNA knots and the science of falling through the Earth.” Thankfully, he was game to talk to us about the Avengers: Endgame Thanos ass theory.

“The basic situation here is one of constrained expansion,” Klotz begins, comparing Ant-Man’s hypothetical attack to filling a water bottle to the brim, then freezing it. When the water freezes and turns to ice, it will expand, which will break the container. What if it doesn’t bust? The “much less likely scenario,” he says, is that the container will be strong enough to prevent breaking, so “the pressure inside the container will increase until the water turns into an exotic higher-density phase of ice.”

So in Endgame, he says, Thanos’ rectum is the container and Ant-Man’s body is the water. The question is: Is Ant-Man’s expansion greater than the compressive tolerance of Thanos’ ass?

“I don’t know,” he says, “but I’ll try to find out.”

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Dismissing Variables

Ant-Man’s physical makeup — and the mechanics of his expansion inside Thanos’ butthole — must be taken into consideration.

“If Ant-Man were more fluid as he expanded, he would splurt through the two sphincters on either side of the rectum, out of the anus and into the colon,” Klotz explains. “However, based on videos of him shrinking and growing, it looks like he can only expand isotropically, without changing shape.”

That is, Ant-Man expands and shrinks while maintaining Ant-Man form; he doesn’t turn into some Flubber abomination. So, Klotz says, we can now ask what happens if Ant-Man fails to expand.

“I can think of three possibilities,” Klotz tells MEL. First, “he just gets stuck, rectum-sized, until he shrinks again.” Second, Ant-Man “tries to expend but builds up so much pressure that it kills him.” Finally, the third scenario: Ant-Man “splurting out of the anus,” Klotz says.

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So, Klotz explains, that leaves us with “three questions that must be answered to get to the bottom of this (no pun intended): How much pressure can a regular rectum take? How much stronger is Thanos than a regular human? And how much pressure can Ant-Man exert when he expands?”


Klotz does the math.

Thanks to an unpleasant-sounding balloon procedure called a rectal compliance test, there is “already scientific knowledge about the expansive tolerance of the human rectum,” Klotz says. Alas, we’re not dealing with a human rectum — we’re dealing with the strongest anal sphincter in the universe, bolstered by nothing less than the Power Stone.

According to the paper I found, a healthy value of rectal compliance is 7 mL/mmHg [a pressure measurement unit],” Klotz explains. “If we divide the volume of a rectum (about 100 mL, based on some quick googling) by the rectal compliance, we get a bulk modulus of 2 kilopascals.”

Bulk modulus? That’s “the relationship between how much bigger or smaller something gets and the pressure that is stretching or compressing it.”

The biophysicist quickly admits that this is a much smaller number than he was expecting: “Apparently it’s really easy to expand a rectum,” he tells MEL. “I’m going to trust the medical literature here over my own intuition.”

The next question is how much stronger is Thanos’ butthole than a normal butthole. Fortunately, similar data exists. “A scientist named Steven Cranford calculated, based on one of Thanos’ crushing feats, that his grip strength is 750,000 times greater than the average man’s, so I will use that ratio.”

Working under Cranford’s calculations, Thanos’ rectal tolerance is “about 15,000 atmospheres, about two thirds of the bulk modulus of water,” Klotz says.

“This is lucky for us,” he notes, “because it tells us that if Ant-Man can expand underwater, then he can expand inside Thanos’ butt. Frustratingly, I cannot find any information on whether Ant-Man can expand underwater or not, but we have reduced a complicated question to a much simpler one, which is all we can hope for with something like this. I would guess that he can, but who knows.”

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The math we’ve done so far really only accounts for Thanos’ ass. The rest of his body may be stronger. Ant-Man’s success “hinges on a number of other things,” Klotz says. “Each tissue and connection in the body has its own strength and its own limits, so even if he can expand through the rectal wall, I don’t know if, for example, the same could be said about breaking the pelvis.”

Then there’s the variable of the Power Stone, which grants the holder (and, presumably, his ass) complete indestructibility when it’s at full capacity. Another element to consider: Doctor Strange, a magician with clairvoyant powers, has surely foreseen all the scenarios in which Ant-Man kills Thanos from inside his ass and knows it is the only way. So perhaps we can assume that Ant-Man will be successful?

Given what we’ve calculated, Klotz says, at the very least it won’t be a wasted effort on Ant-Man’s part. “Literally tearing him a new one will do plenty of damage in its own right,” he concludes, “and at the very least [it’ll] be extremely unpleasant.”