Nuclear Historian Answers Nuclear War Questions

WIRED

Alex Wellerstein joins WIRED to answer the internet's burning questions about nuclear science. Which nations have nuclear bombs? Who decides who gets to have nuclear warheads and who doesn't? Why were Hiroshima and Nagasaki targeted at the end of World War II? What happens to someone's body in an atomic bomb explosion? How does radiation work? Answers to these questions and plenty more await on Nuclear Science Support.  Director: Justin Wolfson Director of Photography: Charlie Jordan Editor: Paul Tael Expert: Alex Wellerstein Line Producer: Jamie Rasmussen Associate Producer: Paul Gulyas; Brandon White Production Manager: Peter Brunette Production Coordinator: Arielle Baron Casting Producer: Lisandro Perez-Rey Camera Operator: Lauren Pruitt Sound Mixer: Sean Paulsen Post Production Supervisor: Christian Olguin Supervising Editor: Erica DeLeo Additional Editor: Samantha DiVito Assistant Editor: Billy Ward

Transcript

00:00I'm Alex Wellerstein. I'm a nuclear historian. I'm here today to answer your questions from the

00:03internet. This is Nuclear History Support. All right, first up, we have one from

00:12at American vs. Gov. What countries have nukes? There are nine countries today in the world with

00:19nuclear weapons that we know about. The United States, first country that got them. The Soviet

00:25Union got them in 1949. Today, those nuclear weapons are in the hands of the Russian Federation.

00:29The United Kingdom, People's Republic of China, France. These are the five officially allowed

00:34countries under the Nuclear Non-Proliferation Treaty to have nuclear weapons. There is also Israel,

00:40India, Pakistan, and North Korea. So nine countries total. There were a few countries that inherited

00:45nuclear weapons after the fall of the Soviet Union, Ukraine, Belarus, and Kazakhstan, but they

00:50returned all of those weapons to Russia in an agreement. LJWitman1 asks, who decides which

00:57countries can have nukes and which countries can't? What are their criteria? The decision

01:02about who can, quote unquote, have nukes and who, quote unquote, can't, this is the result

01:08of a treaty, the Nuclear Non-Proliferation Treaty, which was created in 1968 to try and slow the

01:14spread of nuclear weapons. If you sign the treaty, you agree that only five countries, the countries

01:20that had tested nuclear weapons by 1967 are allowed to have nuclear weapons. Anybody else is not allowed

01:27under that treaty. So if you sign that treaty, you agree those are the only five that have nuclear

01:32weapons and nobody else should have. Pakistan, India, and Israel never signed the treaty, have developed

01:38their own nuclear weapons. There's also North Korea, which was a member of the treaty, but then left the

01:43treaty and made nuclear weapons. Is it illegal for them to have nuclear weapons? Only in the sense that

01:48they're not members of the treaty. What the Nuclear Non-Proliferation Treaty does is it allows any

01:53country without nuclear weapons to know that anybody else who signed the treaty is probably not

01:57also trying to get nuclear weapons. So if you're worried that your rival across the way might be

02:02getting nukes, if you and they both sign the treaty, then you're not going to have to worry as much

02:07about them getting the weapons. It also gives them access to peaceful nuclear technology like nuclear

02:13reactors. It means that they have the right to work on that kind of stuff without worrying that

02:19somebody is going to try and blow up their reactor out of fear that it's a nuclear bomb.

02:24Zipthwang asks, was Iran building a bomb? If so, how close to a bomb was Iran? How were the nuclear

02:30talks going before Israel preemptively attacked? Great question. Was Iran building a nuclear weapon?

02:35No, I don't think anybody thinks Iran was actively building a nuclear weapon. The accusation made

02:41particularly by Israel is that Iran was setting up the conditions under which it could build a

02:47nuclear weapon very quickly if it wanted to. Iran did have a nuclear weapons program before 2003,

02:54and the Iran deal was them essentially saying, we're going to close down and disable all the

03:01little things we were doing that were bad, and we won't do them anymore. Once the United States left

03:06the Iran deal, Iran has been creeping up beyond the limits of the deal. You know, depending on what

03:13your stance is, you either think that's because they are trying to get ready to make a bomb or

03:18because they're trying to compel the United States to come back to the negotiation table as a way of

03:23saying, look, if you leave this deal, which we did, we can do this now. And if you want us to stop,

03:30come back to the deal. Now, how are the nuclear talks going? I don't think that great. I don't think

03:36it's clear exactly what Iran wants per se. They're sort of leaving the door open for different

03:41options, which would make a lot of sense given the recent history that they've had with the

03:45United States and with Israel, but they were not, you know, racing to make a bomb.

03:50Hell here kitten asks, WTF is a nuclear football. It's basically a suitcase. What the nuclear football

03:57is meant to do is allow the president of the United States to order a nuclear strike, even if they are

04:05not in the White House or the Pentagon. If the president is visiting some other country or some

04:10other city, they have basically a very burly, usually military person carrying a very heavy

04:16suitcase around. And in that suitcase, there are information about nuclear war plans. There are

04:23some communication tools probably to allow the president to easily link up with top generals and

04:30advisors and whatever is needed to authenticate the president's nuclear war order if the president

04:37decides to make that. Sophie Kkelson asks, once in a while, I think about how many nukes the U.S.

04:43has lost. How, TF, do you lose a nuke? Find them now. There are a number of quote unquote lost nuclear

04:50weapons. And what that really means is there is a nuclear weapon that was on, say, an airplane or a

04:57submarine. And that airplane either crashed or the submarine sunk. And the weapon is now in the

05:04environment in the world. These kinds of accidents were not super uncommon during the Cold War. The

05:10United States had a program in the 1950s and 1960s to basically have airplanes with nuclear weapons

05:17flying in the air 24 hours a day, seven days a week, so that if nuclear war started, they could have

05:23some kind of guarantee that they'd have a plane ready to retaliate no matter what. Same thing with

05:28submarines. They still go around with nuclear weapons on them all the time. If you have thousands

05:34of airplanes flying tens of thousands of flight hours, you're going to have an accident every once

05:40in a while. Some of these accidents have resulted in like the weapon either itself falling out of the

05:46plane or in the case of a submarine, just going down to the bottom of the ocean. Any kind of mishap you

05:52can imagine a lot of them have happened. In most cases, of course, the United States is very

05:57interested in recovering those weapons, both because it's not a good look to have lost nuclear

06:02weapons, but also they contain the fuel you might need to make more nuclear weapons. And you don't

06:07want that falling in the wrong hands. And so the U.S. always tried to recover these things. But

06:12sometimes the warhead sunk so deep underground that after weeks of trying to dig it out, they couldn't

06:18get it. Or it's at the bottom of the ocean and they couldn't find it. They're lost in the sense

06:22that the U.S. can't recover them, not that they don't know more or less where they are. And they're

06:28lost in the sense that the U.S. couldn't recover them and thinks nobody else could either and decided

06:33to sort of cut their losses. And, you know, maybe they put a monument that says, don't dig here. But

06:38they concluded that if the army couldn't dig this thing up, nobody else could either.

06:43Matilda Mother 67 asks, why did the United States bomb Hiroshima and Nagasaki instead of some military

06:49headquarters or other places where civilians weren't? There were a lot of processes and meetings

06:56and decisions made along the way about what this bomb was, how it should work, what it would be used

07:04against. At the beginning of making the bomb, like say 1943, the attitude was, we'll probably use this

07:11against some sort of military installation. The first target they even discussed was basically

07:17the Japanese equivalent of Pearl Harbor. It's called truck. And sure, there would be some civilians

07:22there, but it's not dropping it in the middle of a city. By 1945, two years later, one, truck is not

07:30an issue militarily anymore. They'd cut it off. It was not a target. And two, the United States had gotten

07:35in the habit of targeting cities. In the early part of 1945, the United States began firebombing

07:41Japanese cities with Nepal. They burnt Tokyo. They burnt Osaka. They ended up burning 67 Japanese

07:47cities by dropping basically flaming gasoline on them. The other issue is that the bomb they ended

07:53up with was one that would work best if you detonated it pretty high in the air. If you detonated high in the

07:59air, you spread the blast damage out wider, but your blast damage is also less intense. So if you're

08:05target is some built up bunker, you're not going to destroy it by blowing up the bomb in the air.

08:10If your target is a house, you don't need as much blast pressure to destroy it. So they had a bomb

08:17that they ended up with through technical decisions along the way that would be most impressive if you

08:24used it on a city. And they had many discussions about what kind of target, what's the goal of this

08:30weapon? The goal of the weapon was essentially psychological. They wanted to cause the Japanese

08:37people to say, we cannot tolerate this. We cannot win. Let's surrender. One of the people involved in

08:44the discussion said that the goal was to have the Japanese basically capitulate to the power of the

08:50universe. Oh, you don't want to surrender to the United States or the Soviet Union? Well, what if we use

08:56the power of the sun to destroy you? To me, the really interesting thing is that Hiroshima was not

09:01their first choice at all for a target. The first choice that the military had was Kyoto, former

09:07capital of Japan. It was taken off the list by the secretary of war, Henry Stimson, because he thought

09:13that the city was too civilian in nature, was a cultural heritage site. Hiroshima got then bumped up

09:20to first place because it had some military bases and manufacturing in it. It had not yet been bombed.

09:28Its geography was such that it was sort of like a bowl-shaped city surrounded by hills, and that

09:33meant it would kind of intensify the effect of the weapon. So from the point of view of the United States

09:39military and the scientists who consulted from them, it was a perfectly good target. Nagasaki was only added

09:44to the target list after Kyoto was taken off of it because they wanted a backup target. The actual

09:50target for the second bombing run was a different city, Kokura. Kokura had a major arsenal in the

09:57center of it that produced weapons for the Japanese and was surrounded by workers' houses. So by their

10:03criteria, this was a great target. When they got to Kokura, though, they found that it was covered by

10:09smoke or clouds or haze. It's not clear exactly what, but they could not see it to exactly target

10:14the bomb on it. So they went to the backup target, which was Nagasaki, which was nearby.

10:19Matthew S. Waite asks, I can't help but think gun control debates mirror that of nuclear weapons

10:24proliferation. Does every country having nukes make us all safer? This is a classic question. Is the

10:30world safer if there are only a couple countries with nuclear weapons, or would it be safer if all

10:35the countries had nuclear weapons? If there were a lot of countries with nuclear weapons, presumably they

10:39would be very hesitant to go to war with one another because the consequences would be terrible.

10:44On the other hand, if you think that the chances of either accidental nuclear war or people thinking

10:51nuclear war was winnable or terrorism, if you think the chances of those are relatively high,

10:57then more nuclear weapons in the world is a much more dangerous world because that's a world in

11:00which nuclear war is more likely to occur. It's not clear what the answer is here. Generally speaking,

11:07I'm more swayed by the arguments that it is a little bit dangerous to have lots of countries with

11:13nuclear weapons in the world. I know that's a really hot take, but I don't trust the systems or

11:19governments of these countries to be sort of perfect with regard to they're not starting a

11:26nuclear war. And if you don't think that they're going to be perfect, then it becomes very dangerous

11:31over time the more people who have nuclear weapons. Hugebag69 asks, enriched uranium. What is it? What is the

11:39process of enriching? How dangerous is it on its own? So uranium is an element. You can mine it out of

11:45the ground. It's a rock and even get it out of seawater. It's relatively abundant by itself. If we

11:51went out and got a rock of uranium, uranium we would find would have two types of uranium inside of it.

11:58One of them would be called uranium-238. There'd be 99% of that in any uranium we pulled out of the

12:04ground. And less than 1% of it, it's like 0.7% would be uranium-235. So these are two of the same

12:12element, but they differ in that uranium-238 has three more neutrons inside of it than uranium-235.

12:18So we call these different isotopes. Uranium-238 will not explode in a bomb. Uranium-235 will.

12:26So enrichment is when we take this uranium and pull out the uranium-235 almost literally atom by atom.

12:33This is a very difficult process to do because the difference between these is only three neutrons,

12:38which is not very much. They are chemically identical. So we have to rely on the fact that

12:43one's a little bit lighter than the other. So uranium enrichment, there's different processes

12:48for doing it. And the most famous right now is the centrifuge, where we basically are spinning

12:52around uranium in a gaseous form. And as we spin it, the centrifugal forces will cause

12:58the lighter uranium to move slightly in more one direction and the heavier slightly in another. And

13:04we skim off the part that would have the lighter. And we have to run it through another centrifuge

13:08to skim off a little more, and then another to skim off a little more. And so we're taking advantage

13:13of little tiny statistical differences in how heavy they are. And we do this for thousands of

13:18centrifuges. And you will eventually end up with more and more uranium-235. When we want uranium

13:25for fuel in a nuclear power plant, we tend to enrich it up to about 3% uranium-235. When we

13:31want it for a bomb, we want it to be much higher than that. The bomb dropped on Hiroshima was about

13:3780% uranium-235. In the United States now, the standard amount in a weapon, if we use enriched

13:43uranium, is around 93% enriched uranium. The fourth resident asks, wait, but Einstein was not a part of

13:50the Manhattan Project. So how or why did they get his help during it? Einstein's role in the atomic

13:55bomb was at the very beginning, he wrote a letter to President Roosevelt saying, hey, we have learned

14:03how to split atoms. Germany might be working on this. Maybe somebody in the United States government

14:08should be looking at this. And that's more or less his role in the whole Manhattan Project. Why didn't

14:13they use him? They actually did consider using him. And they concluded two things. One, Einstein at this

14:18point is pretty old. He's not your cutting-edge scientist. The kind of science he does is not

14:23actually that useful for making an atomic bomb. Yes, yes, equals MC square, sort of explains in a way

14:30where the energy comes from an atomic bomb. It does not tell you how to make one. It doesn't tell you how

14:35to make a factory and design the things and the parts. You don't need somebody like Einstein to do

14:39that. The other thing is that Einstein was considered politically radical. He supported really

14:44out their ideas like civil rights. And that, at that time, meant that he was considered to be

14:50politically questionable by some people in the U.S. government. And so if he is the kind of person

14:57who, to be fair, might have strong ideas about how atomic bombs ought to be used and has a lot of fame

15:02and is the kind of person that presidents would listen to, maybe you don't want him to be in the

15:07project if your goal is to just sort of get the thing done. Coastal Buckeye asks,

15:10is there still a radiation field in Hiroshima or Nagasaki? Great question. Hiroshima and Nagasaki

15:15had atomic bombs dropped on them in World War II. Here's Hiroshima. This is not far from Ground Zero.

15:21You can see this building, the very famous atomic bomb dome. Ground Zero is very close to that.

15:26These weapons were detonated very high above the city. If you look at pictures of these bombs,

15:33this is a mock-up of the kind of bomb dropped in Hiroshima. This is one for Nagasaki. You can see

15:38they've got this equipment on them, weird little wires. These are fuses that detect how high above

15:44the ground the bomb is. And they were set to detonate at the height that the scientists had

15:49calculated would maximize the blast effect of the weapon. You can think of the blast as going sort

15:56of as a sphere out from the explosion. And if it's really close to the ground, a lot of that is going

16:01to be going sort of sideways. And it's going to be running into buildings. And they're going to be

16:06absorbing the energy and also reducing it as a consequence. If you detonate it in the air,

16:12you're sort of going down with the blast force. And it's going to be much wider area. So it was

16:18detonated high in the air. The consequence of that is the people at Hiroshima and Nagasaki,

16:23they got a blast of immediate radiation. It's like almost like a light switch turning on and off.

16:28You wouldn't be able to see it, but imagine it's just like a quick exposure, almost like x-rays or

16:33something like that. And that was very bad for the people who were in the range at which that would

16:38occur. But it's a short, immediate effect. It's sort of almost like a one-time exposure.

16:43The thing that makes nuclear weapons so contaminating is the nuclear fallout. These are the split atoms

16:49from the weapon. And these are in the mushroom cloud. And one interesting thing you can actually see in

16:55some of these pictures. So this is a picture of Nagasaki's mushroom cloud taken from someone on

17:01one of the airplanes that was involved in the bombing of Nagasaki. And if you look closely,

17:06you can see the cloud is actually two different parts. You have this top part, the head, and then

17:12you have this dark stem underneath it. And you can actually see that they don't connect. This is an

17:17artifact of the weapon being detonated higher up. This cloud contains the most radioactive residues from

17:24the bomb. This is mostly created by fire and debris and dust that is being pulled up by the negative

17:32pressure of this cloud moving upwards. And it is not that radioactive. Now, if this bomb had been

17:39detonated on the ground, these two parts would be mixed together. And if that happens, then the

17:45radioactive bits attach themselves to the dirt and then fall out of the cloud relatively quickly because

17:52the dirt is pretty heavy relatively speaking. If it doesn't happen, this part stays relatively light

17:58and it'll blow on with the wind. And as it blows, it'll take a while for it to start to fall out of

18:04the cloud. And what that gets you is two things. One, the most radioactive stuff with short half-lives,

18:10they get to sort of burn out before they fall down. But this cloud, because it has time to spread,

18:16it means that it's diluting. So more area gets some radioactive bits, but they get less like per

18:23square meter per square foot. So the amount of radiation is diffused in a way that doesn't

18:29actually make it a contamination hazard. So the long and short of it is because they're detonated

18:33high altitude, they did not really get a lot of nuclear fallout. Today, they are not radioactive in

18:39any significant way. If the bombs had been detonated on the ground, it would be a different story.

18:43XJSSCX on Reddit asks, what actually happens to someone in an atomic bomb explosion? The first

18:50thing, if you saw a nuclear weapon go off, one, the brightness of it, it's very bright. With that

18:55brightness comes this flash of radiation. So if you are close enough to an atomic bomb, you will

19:01instantly get a lot of radioactive particles, gamma rays, beta particles, things like this,

19:07going through your body. For the Hiroshima bomb, the radius from the detonation point

19:13where you would get a fatal amount of radiation is about three quarters of a mile. If you're

19:19in that zone, you're probably dead no matter what happens next. If you're a little out of

19:22that zone, you might get some radiation. That is probably not your biggest concern for most

19:27nuclear weapons, but it's not the best, right? The next thing that you would experience is heat.

19:33The surface of the fireball is hotter than the sun briefly. If you're in direct line of sight

19:39with this, it's sort of like if the sun was suddenly a lot closer to you than it is right

19:45now. If you're really close to the fireball, you could be literally vaporized, as people

19:50say. Most of the people at Hiroshima and Nagasaki are not vaporized or melted or anything, but

19:56they were severely burned. You can get really bad burns. The next effect, that fireball in

20:03that first split second of it going off is sort of superheating the air around it. And

20:10what's going to happen then is it's going to be moving outward. This is the shock wave,

20:13the blast wave. And as it goes out, it's this sort of wave of pressure that's going to intersect

20:19with the ground and move along it and push. And the more it goes, the weaker it goes. But

20:25this is powerful enough at different distances to do a lot of damage. So at Hiroshima, if you were

20:32about 300 meters from ground zero, that would be enough blast pressure, about 20 pounds per square

20:38inch, to destroy almost any building that is standing. Any buildings that are still remaining

20:44at Hiroshima, like the famous atomic bomb dome, are gutted. Like nobody's doing well who was inside

20:50this building. They're all dead. If you go out a little further, if you were about 1.7 kilometers

20:56from ground zero at Hiroshima, that's the radius at which there's enough to definitely destroy

21:01light structures. So houses, things like that. You go out further to maybe about 2.8 miles.

21:09And now the blast wave is weak enough that the most it's doing is sort of breaking windows.

21:13That's still not great. If you're standing at a window, as this thing comes to you, it's going

21:17to break all the glass and push it into you. And now you've been injured by a window. So depending

21:23on where you are, there's different effects that can happen. Strandfort asks on Reddit,

21:28for how long do I stay in a fallout shelter after a nuclear war? The amount of time you

21:32need to stay in there depends on how radioactive the fallout is. Now, a lot of people think of

21:37fallout shelters like the game or show Fallout, and they think we're going to stay in there

21:41for 100 years or something like that. That is not what they are built to do. They are built

21:45to basically accommodate people to maybe stay in there for at most two weeks, maybe even less.

21:50You might recognize these signs. These are from the 1960s program to identify places that

21:57could be used as fallout shelters. A fallout shelter is not meant to protect you from a

22:03nuclear weapon that drops on you. What it's meant to do is be a place that puts mass, so

22:09concrete or dirt, ideally, in between you and the outside world so that if radioactive particles

22:15fall on top of you, there is something in between you and them to cut the amount of radiation.

22:22So you can think of it when you go to the dentist and they take an x-ray and they put one of these

22:26heavy lead aprons on you. It's sort of like a building equivalent of that lead apron.

22:32Max 65 asks, how dangerous is Chernobyl today? There are people who visit Chernobyl or did before the

22:38Ukraine-Russia war. There are people who work at Chernobyl still today, and they have means of

22:44checking how much radiation they pick up. There are tools called dosimeters. This is one from the

22:50Cold War. It basically tracks how much radiation you get. This one works by looking through it at

22:56a light, and a little wire moves as it absorbs radiation. And the workers on these kinds of places

23:02are making sure that the amount of radiation they pick up is within what we consider to be the safe

23:08amounts. You probably wouldn't want to live in Chernobyl, though. There are some people who have been

23:13living there, people who used to live there that eventually went back, and they've said, you know

23:17what, I just want to live in my own home. I don't care if it's contaminated. Are they at risk? Well,

23:22a little, but if they're 70 years old and living in Chernobyl increases their cancer risk by, say,

23:275%, they're probably going to die of something else anyway, because it takes a long time for those

23:32kinds of cancers to develop. If we talk about what if 10,000 people live there and the cancer risk goes up

23:38by 5%, you're going to start seeing that as 5% more cancers in this community than you would

23:44already have. Austin's Burner asks, how TF does radiation work? How does a place be radioactive?

23:50How does someone die from radiation poisoning? You can think of it as little particles. That's

23:54basically what the word radiation means. It means little things spitting out. And there's lots of

23:58different kinds of radiation. The kind that people are usually talking about is called ionizing

24:03radiation. And that means radiation of types and energies that are capable of knocking electrons

24:10off of other atoms and molecules. The problem is that if you're made out of cells, especially if you

24:16have DNA, ionizing things, that changes their chemistry. And if you were a rock, who would care?

24:23But if you're a biological system, that means you're like shooting little bullets into cells,

24:29which can kill them, which is fine. You have a lot of cells. Or it can, in some rare cases,

24:35change the DNA in a way that turns it into a cancerous cell. Radiation poisoning is when you

24:40get so much radiation that the number of cells you're killing becomes actually significant.

24:46So radioactive contamination is when a place has radioactive stuff that is sending out the

24:53radiation. So I have a Geiger counter here. A Geiger counter is a tool for detecting radioactivity.

24:59So what it has in it is a sensor that can tell when a radioactive particle has gone across it.

25:04And whenever it does this, you're hearing this little click happening. Why does it click? Because

25:09we hooked it to a speaker and we want to be able to hear it. Now, I could have a radioactive substance.

25:15This is trinitite, the glass from the first nuclear test. This is something that contains trace

25:21amounts of plutonium and uranium and long-lived fission products. And if I put the sensor over it,

25:27you can hear that the clicking increases by a bit. The air right above this radioactive material

25:36is getting about twice as much radioactivity as the normal air around here. That's not that much.

25:42If this was something actually dangerous, it would be getting a lot more, a hundred times more. But

25:47this is the sort of tool that lets you measure when these radioactive particles are being emitted

25:52from this radioactive substance. GlitteringWeakness88 on Reddit asks,

25:58what is the theoretical upper power limit of a nuke we can produce currently? If you wanted to,

26:04you can make essentially an unlimited power nuclear weapon. A thermonuclear weapon basically works by

26:10having one nuclear weapon act as sort of the detonator for another nuclear weapon. And if you wanted to,

26:16you could make that weapon be the detonator for another nuclear weapon and that detonator for

26:20another nuclear weapon. The largest nuclear weapon ever made was the Soviet Tsar Bomba. It was tested

26:27in 1961 as a 50 megaton sized weapon. So 50 million tons of TNT. And that was at half its power. It was

26:36deliberately scaled back by half to prevent contamination. By comparison, the Hiroshima bomb

26:42is 15,000 tons of TNT. So this is a weapon thousands of times more powerful than the first

26:49atomic bombs. The United States could have done that. They actually looked into doing that kind of

26:55thing in the Cold War and decided not to. So the largest weapon that I know of that was ever taken

27:01seriously by weapon scientists in the United States was called the Sundial. It was never built. They didn't

27:07get that far in researching it. But it was a weapon that was 10,000 megatons of TNT. Why did the United

27:14States not do this? Why did even the Soviet Union not really do this? The Tsar Bomba was sort of a stunt

27:21more than a practical weapon. The answer is, one, you don't get that much from it. Because of the way

27:27nuclear weapons work, because they're basically a sphere expanding in the air. Think of it as a balloon

27:34that you're like pumping air into. What we care about for the damage is the amount of the balloon

27:39that's going to touch the ground. A lot of that balloon is not going to touch the ground. And as

27:43we're putting energy into it, the part that's touching the ground, it's not increasing as a linear

27:48function. It's increasing as what's called a cubic root. The takeaway is, if we wanted to double the

27:54damage of a weapon, we typically have to increase the size of the weapon by around eight times.

28:00The real killer, though, is to make them bigger, we do more or less have to linearly increase the

28:07weight and size of the weapon. So the Tsar Bomba is a powerful weapon, but it's the size of a school

28:12bus. That weapon could not fit inside the airplane that carried it and had to sort of sit underneath

28:18it like a big egg. If you're another country and you see a plane coming towards you with a big egg

28:24attached to it, you're going to really work hard to shoot that down. That is not convenient.

28:28If you're talking about weapons that are the size of the sundial, 10,000 megatons,

28:32that's a weapon that's probably the size of the space shuttle. That's not easy to use.

28:37That's not easy to deploy. That's going to be also really expensive. That is an aside.

28:42Trends in nuclear weapons design didn't go in that area. What they did was they went for more compact

28:48weapons. So you can put 10 of them onto one missile and then target 10 targets with one missile.

28:54It's a weapon the size of a large trash can, but it's 30 times more explosive than Hiroshima.

28:59That's peak weapons design, not just more bang.

29:03Perfect Football 2616 on Reddit asks,

29:06Did the tactic of duck and cover provide any protection from an actual nuclear strike?

29:10Duck and cover was a public education program put out by the United States government,

29:15and it was particularly aimed at school children. And you'll see pictures of children hiding under

29:20their desk from this period. There was a short film created with a turtle cartoon mascot,

29:27Bert the Turtle, trying to talk to students about nuclear war. And of course, a lot of it looks

29:32pretty sketchy. There are lots of people who lived through this who said, that was the moment I

29:37realized adults did not know what they were doing, if they thought this desk was going to protect me

29:41from an atomic bomb. They are not saying that if an atomic bomb lands on your school,

29:46your desk is going to keep you safe. What they are doing with this policy is saying there's going

29:52to be an area where the bomb goes off where you just have no help. I'm sorry. They don't say this

29:56in the movie because it's aimed at children. They don't even say this at things aimed at adults

30:00because the United States government has a very hard time admitting that people are going to die

30:04in large numbers if nuclear weapons go off, even though it is self-evidently true. There's also a zone

30:08much further out where you're far enough away that you'll say, what was that? Oh my gosh,

30:12what's going on? You are not going to be affected by the weapon, right? You're going to learn from

30:17the news. So in between is a pretty small zone where you have a chance of surviving if you do

30:25the right thing. Duck and cover is for that zone. And it's for an area where the blast pressure is

30:32going to be enough that it is going to be sort of like an earthquake. They're worried about the

30:36ceiling collapsing. They're worried about windows breaking. They're worried that if you have exposed

30:40skin, you might get burned. And so the tactic is get down, cover up your most vulnerable parts,

30:46and you can increase your chance of survival a little bit that way. The Mute Newt on Reddit,

30:52great name. How close did Nazi Germany actually get to developing an atomic weapon? Nazi Germany did

30:57not get close to making an atomic bomb. At the end of World War II, they were almost to the place that

31:04the United States was in 1942. So they almost had a prototype nuclear reactor, not an atomic bomb.

31:13Why not? Because they weren't trying to make an atomic bomb. I know that's a hot take because we like

31:17to talk about the race for the atomic bomb. The Americans feared they were working on atomic bomb,

31:22but the Germans had actually decided they were going to have a pretty small research program for

31:28nuclear reactors, maybe in the future making atomic bombs. But they concluded in 1942 that it would

31:35take a lot of work from a lot of their scientists to try and make an atomic bomb that could be useful

31:41for World War II. And in 1942, they thought they were going to win the war. So they didn't think they

31:47needed an atomic bomb. They thought that making an atomic bomb would be very hard, and they were correct

31:51on that. And as a result, they thought nobody else was going to make one either. So this is a problem for

31:56after the war. Well, that's it. That's all the questions. I hope you learned something. I hope

32:00you don't make an atomic bomb. Until next time.

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