- This is what really
happened to Iron Man. (intense music) It was a snap heard round the universe that brought this
iteration of the Marvel's Cinematic Universe to a close. It was the same snap that closed the book on the hero that started it all. But, before we let Iron Man go, what really happened to Tony Stark? What does snapping an Infinity
Gauntlet actually do to you? (upbeat electronic music) (snaps) Avengers Endgame has
already made its mark. It has smashed over a
dozen box office records like a golden sword boomerang thing smashing a shiny vibranium shield from a different timeline, and it stands as a satisfying conclusion to the story arcs of many of our favorite characters, Iron Man included. In Endgame, Tony has
to snap one final time to bring all Thanos's evil plans to an end and the snap itself is
what ends Tony's life. What does the Infinity
Gauntlet snap actually do? And does the movie's implied physics fit with the real world? Can we figure that out? I think so. First of all, what is in a snap? Well, helpfully, in Avengers Endgame, professor Hulk points out that when the Infinity Gauntlet snaps, it releases a tidal wave
of radiation, most of it in the gamma ray portion of the
electromagnetic spectrum. Gamma radiation, denoted
with this symbol here, sounds scary and it can be, but gamma radiation is just light, like visible light is light, or radio waves way down here are light. What makes it potentially
dangerous for human beings is that it also has the
shortest wave length and the highest energy
among photons of light. And that high energy can do
weird stuff to the human body. I need to buy new gloves. How much gamma ray energy are we really talking about, though? Well, helpfully again,
Mr. Stark has an offhand comment in Avengers Endgame where he says the Gauntlet, equipped with
all six infinity stones, could power a continent. Hey Friday, why don't you pull up the annual power consumption
from North America, please? - [Friday] Sure thing, Science Boy. - You know my name. The problem with a
power value like this is that power is defined as a
unit of energy per unit of time joules per second, if you
do all the conversions here. So we can only really figure
out how much energy is released during a single snap if we all agree on how long a snap takes. How long does a snap take? (snapping) Ah! Hm, maybe about the time
it takes you to blink? Sure, let's say about a tenth of a second is how long a snap takes. Hey Friday, why don't you hit me up with that sweet multiplication? - [Friday] You can't
just take 10% of that? - I mean, I could, but you-- Doing the math ourselves and converting, we get around 54 billion
joules worth of energy for a single snap if
all of our assumptions and calculations are correct. Now, if 54 billion joules
worth of gamma radiation sounds bad, that's because it would be. Nuclear bombs and dangerous
radiation have been linked in our minds for a long time, but when an atom bomb actually goes off, only a small minority of
the energy goes into the kinds of radiation that
we've been talking about. The majority goes into the blast itself and the heat generated. Still, atomic bombs like
the one dropped on Hiroshima during World War II
release trillions of joules worth of gamma ray
radiation when they explode. Our Infinity Gauntlet
snap would have about 1% of this kind of energy. That sounds small, but 1% of a trillion is still a lot, and
remember it is all happening literally this close to Tony's face. A sphere of radiation extending
outward in all directions. It would expose Tony to more radiation than any human has ever
experienced at one time. (explosion) (coughs) What Iron Man would have experienced next is the worst case of radiation
poisoning in history. Radiation is all around us all the time, constantly hitting our bodies. There is the more harmless radiation, like the visible light hitting
the back of your eyeballs from the screen you are
watching me on right now, and there is the more harmful radiation that comes from background sources, like cosmic rays from
space and radioactive atoms in the food that we eat and
the air that we breathe. We really only concern
ourselves with measuring how much of that dangerous
radiation we are absorbing. So here is a graph of that
measured in millisieverts, which just gets at how much radiation our body is absorbing over time. Now, here is how much the average person in the US absorbs per year. Here is how much
radiation you would absorb if you got a single abdominal CT scan. Here is how much you get after six months aboard the International Space Station. Cosmic rays and all that. And here is how much you would get on a realistic trip to Mars. Oh, and here's how much you get from eating a single banana. Tony, though, would get a
lot more exposure than this. I cannot even show you on
the scale of this graph how much radiation Tony
would be exposed to. If these are millisieverts,
a thousandth of a sievert, then he would be exposed
to billions of those. And this is why the Hulk volunteered to snap the gauntlet the first time. Normal humans simply aren't evolved to handle this kind of radiation. Wow, I should get that looked at! And my glove budget's gettin' too big! As you have probably guessed by now, the snap radiation
levels that we calculated would in fact be 100% lethal. But what would happen to Tony next? Would the effects that we see in the film fit with what we know happens during extreme radiation poisoning? As we've gone through many
times on this program, the dangerous radiation
we've been talking about is more specifically ionizing radiation, and it's dangerous
because it has the energy to rip electrons from atoms,
and once that happens, they become ions, ionized. And these new ions can
interact with our bodies in different and potentially fatal ways. This is how much radiation
your body absorbs every year, just from background sources. You don't even notice. Multiply this value by a few hundred, and now you are at the
radiation exposure limit for astronauts over their entire career. Nothing crazy happening to their bodies, but there is now a slight
increase in their risk of cancer. Bump this up again, and now
things are getting dangerous. At four to five sieverts,
an acute exposure, a very, very quick exposure,
will lead to widespread cellular damage, cognitive
impairment, extreme nausea and vomiting setting
in within a few hours, and 50% of untreated
people who are exposed to this kind of radiation
will not make it. Even with treatment, an
exposure to 10 sieverts or more will lead to death in 100% of people. Organ failure, extreme lethargy, and death within a few days to hours to minutes. Using our numbers, during
a short infinity snap, Tony might be exposed to
more than a million sieverts. Obviously, a beyond lethal dose. This could plausibly lead
to the extreme lethargy and confusion and very quick
demise that we see in Endgame. And the scary thing about
radiation exposure like this, is all it takes is a brief flash of it. Flash. If this makes sense, and
what it could do to Tony makes sense, what about the flash of light that the snap makes? Could that be more than
artistic license, too? (snaps) On May 21, 1946, physicist
Louis Slotin was working at the famous Los Alomos National Laboratory in New Mexico. And on this day in history, he decided to do something extremely dangerous. What Richard Feynman called
tickling the dragon's tail. Slotin was experimenting with a core of radioactive plutonium,
and he was performing so-called criticality tests. The idea here is is that
you can make a sub-critical piece of nuclear material
go instantly critical if you surround it with enough material in the right orientation
to reflect its radiation back in on itself and
start a chain reaction. On that day in 1946, Louis
Slotin was doing this with two halves of a berilium sphere, lowering those halves
around this plutonium core. But instead of some
complicated and very careful apparatus to do this, he
was just using a screwdriver to keep the two halves
of the sphere apart. And then the screwdriver slipped. (whirring) The core went instantly critical before Slotin could separate the sphere, and those who were there that day reported a flash of blue light, and a wave of heat. In that instant, standing
literally this close to the assembly, Slotin
had received a dose of 21 sieverts, and died nine days later. Those who were in the room with him reported that he said,
after this flash of light, "Well, that does it." It's a morbid tale, but it actually provides something
useful for our purposes. The Infinity Gauntlet, if
it is releasing radiation and that radiation is smashing
into the air around it, it could produce a flash of light. It doesn't just have to be movie magic, it could be deadly serious. This is all very sad and somber, but let's make Tony proud
and go one step further. How could you make an infinity snap safer? Everything does look cooler in these! There are three simple ways to increase your radiation protection. Friday, tell 'em. - [Friday] You said simple? Can't you just tell them? - Can I just tell them, what's the point of having cool technology if you're not going to use it whenever. The first protection is time,
and that should be obvious. If you are exposed to
some source of radiation for some period of time, the
less time you're exposed, the less exposure you
get, which makes sense. But how do you shorten a snap if we want to get less radiation from it? I guess it has to be a
snap because of the movie but would an infinity clap be faster? (claps) Is that faster? Nah, it just looks dumb. The point is, the math is simple. The less amount of time that
the infinity power is active, the less radiation you get. (claps) You could also increase
the distance between you and the Infinity
Gauntlet when it snaps to decrease the amount of
radiation you'd receive from it. Radiation coming from a point
source like a light bulb or gamma rays from our
Infinity Gauntlet here, will shoot off in all
directions in a sphere and decrease in intensity as it does so. In other words it follows
the inverse-square law. As the gamma rays shot out
of the Infinity Gauntlet during the snap in Endgame,
they would spread out and, per unit area, their
intensity would decrease proportional to one over
the square of the distance. You can see these areas
getting much larger as the distance increases. So the intensity decreases
very quickly if you get further and further away
from the Infinity Gauntlet. So if you could figure out a way to take the Infinity Gauntlet
and move it to a distance and then snap it from
there, you would increase your chances of not being
totally Iron Man-ed. However, with our numbers, you would have to be hundreds of
meters away from that thing. (snap)
(whirring) Finally, we could shield ourselves from the radiation of the snap. The radiation that we've
been talking about so far can be frightening, but
some of it can be stopped in its tracks with the right sheilding. Kind of like I'm stopping the light from bouncing off of my face
and making it to your eyeballs just with a sheet of paper. Wow! The problem with gamma rays is
that a simple sheet of paper would not be enough to stop them. It would be enough to stop
alpha particles, for example, and a thin sheet of aluminum
would be able to stop a stream of electrons,
but gamma radiation, by its very nature, is
extremely penetrating. You would need a wall of lead or water just to reduce your
exposure, and you're still probably not going to stop all of it. Maybe Tony could come up
with some ultra thin material that's a metal that can go into his suit that could stop all that radiation though. If he could then you
could imagine the perfect, non-sacrificial scenario,
where Tony has the gauntlet with all the infinity stones on it. And then he uses his Stark
nanotech to shield himself from the snap, holding
the gauntlet as far away from him as humanly possible,
and then trying to snap as slowly as possible? That would be everything he
could do to reduce his exposure if he still had to have
the gauntlet on his hand. But I guess that just
wasn't possible for him. It just was never going
to be his end game. - [Friday] Ooh, dramatic. - I was trying to be
like, emotional and cool. Hey, shut up. You do it. So, what really happened to Iron Man? He heroically exposed himself
to more ionizing radiation than any human in history,
in order to finally defeat Thanos and save
the entire universe. And if it really went down
this way, with gamma rays and radiation, not only
would that radiation close Tony's Story Arc Reactor, it would create a flash of light just like we see in both Infinity War and Endgame. In terms of coming up with
an emotionally satisfying and scientifically
accurate sendoff for Stark, the Avengers assembled
a decent explanation. - [Friday] Because science. (upbeat electronic music) - So we mentioned shielding
last, and if you think back to Endgame, there's a
problem with shielding. Specifically when the Hulk snaps the Infinity Gauntlet himself,
everyone's just standing in the room and they kind
of brace for the impact of the snap and Hawkeye
just went kind of like, uh. And Iron Man puts his suit on, puts his shield up and
people are like, uh. But if it's really gamma
radiation, every human, non-shielded by a giant wall in that room would have also... not made it. I would have loved that ending not 3,000. Thank you so much for watching, Bergita. If you enjoyed this episode follow us here on social media and you can suggest ideas for future episodes, and
hey, sometimes I use them. Also, the full The Science
of Mortal Combat series is now live on our channel. Six episodes, six behind
the scenes episodes, wow it was a lot of fun. You're gonna watch us punch stuff and burn stuff and smash stuff. So give it a, give it a
smash that view button. (electronic music)
He was stolen from us. That's what really happened to him. Damn you, Endgame!