WEBVTT - TechStuff Classic: How Nuclear Weapons Work 0:00:04.120 --> 0:00:07.160 Get in text with technology with tech Stuff from how 0:00:07.200 --> 0:00:14.160 stuff works dot com. Hey there, and welcome to tech Stuff. 0:00:14.280 --> 0:00:16.919 I'm your host, Jonathan's trick Land. I'm an executive producer 0:00:16.960 --> 0:00:22.079 and how Stuff Works in love all things to though 0:00:22.120 --> 0:00:25.000 maybe not this next topic. Maybe I should say I 0:00:25.040 --> 0:00:29.200 love most things tech. It's time for another classic episode, 0:00:29.760 --> 0:00:33.120 and this particular topic is a pretty tough one. It's 0:00:33.159 --> 0:00:37.240 about how nuclear weapons work. And it's not a topic 0:00:37.360 --> 0:00:42.760 that I necessarily wanted to jump on and cover, but 0:00:42.800 --> 0:00:46.400 I feel it's an important one. Nuclear weapons are frequently 0:00:46.840 --> 0:00:50.560 part of a discussion about global events and global politics, 0:00:51.000 --> 0:00:53.880 and so I thought it would be useful to revisit 0:00:53.920 --> 0:00:57.560 this classic episode where we talk about exactly how these 0:00:57.600 --> 0:01:03.639 weapons work. So enjoy Today. We wanted to talk about 0:01:03.680 --> 0:01:07.200 a subject that is, uh it's pretty terrifying. We're talking 0:01:07.200 --> 0:01:13.360 about nuclear weapons. Yes, yes, nuclear, not nuclear. He was. 0:01:13.600 --> 0:01:15.640 I was teasing him about this before and he said 0:01:16.080 --> 0:01:18.480 that I better not. I'm not gonna say nuclear. I 0:01:18.480 --> 0:01:21.280 mean other than just them. Um. Well, one of the 0:01:21.319 --> 0:01:23.880 reasons I wanted to uh to talk about this today 0:01:23.959 --> 0:01:26.200 is because it's been in the news a lot lately. Um. 0:01:26.240 --> 0:01:31.360 Of course, uh iran um is rumored or depending on 0:01:31.360 --> 0:01:33.400 whom you ask, more than rumored to be working on 0:01:33.520 --> 0:01:37.759 nuclear weapons program and um, you know that that's been 0:01:37.959 --> 0:01:40.640 a busy topic. I was about to say, a hot topic. 0:01:40.760 --> 0:01:43.440 Let's not go there um lately, and I thought, well, 0:01:43.480 --> 0:01:46.400 you know, why don't we We've never really talked about, um, 0:01:46.480 --> 0:01:53.000 the technology that makes nuclear weapons possible. Um. And while 0:01:53.040 --> 0:01:58.680 I'm not particularly fond of things that cause death and destruction, uh, 0:01:58.760 --> 0:02:01.400 the the actual bombs themselves, how they make them work 0:02:01.680 --> 0:02:04.720 is kind of interesting, and it's it's important stuff. I mean, 0:02:04.800 --> 0:02:06.120 you know, there's a lot of there are a lot 0:02:06.160 --> 0:02:10.120 of discussions about nuclear arms races. You know, we had 0:02:10.720 --> 0:02:13.519 a famous nuclear arms race between the Soviet Union and 0:02:13.560 --> 0:02:18.359 the United States during the Cold War, which uh started 0:02:18.400 --> 0:02:21.280 to look like things were going to to improve, where 0:02:21.480 --> 0:02:24.680 you know, both nations were starting to dismantle a lot 0:02:24.720 --> 0:02:28.160 of their nuclear weapon programs. But then you've got other 0:02:28.240 --> 0:02:32.920 countries like China and India and Pakistan and other countries 0:02:32.960 --> 0:02:35.960 that are that have either have a nuclear weapons program 0:02:36.000 --> 0:02:39.600 or developing. North Korea is another good example. They either 0:02:39.720 --> 0:02:43.480 have a and a fully fledged out nuclear weapons program 0:02:43.560 --> 0:02:46.600 or they're working on it. And uh, it adds a 0:02:46.600 --> 0:02:50.680 lot of concern because these weapons potentially pack an enormous 0:02:50.680 --> 0:02:54.720 punch and it's the kind of weapon that you know, 0:02:54.880 --> 0:02:58.160 most weapons, you use them and then the uh, that 0:02:58.280 --> 0:03:01.880 immediate moment, the aftermath, that's that's all you're dealing with. 0:03:01.960 --> 0:03:05.840 And the aftermath is generally, you know, not not uh, 0:03:05.960 --> 0:03:08.440 something that is perpetual, right, I mean, I mean, you 0:03:08.560 --> 0:03:10.640 might have to do some massive clean up or whatever, 0:03:10.680 --> 0:03:14.040 but that's it. Nuclear weapons are different, and that the 0:03:14.120 --> 0:03:19.120 aftermath can be as destructive or maybe not as destructive, 0:03:19.160 --> 0:03:23.520 but but destructive on their own beyond the initial blast. 0:03:24.160 --> 0:03:28.040 And so plus plus it's possible that the uh, the 0:03:28.040 --> 0:03:34.239 effects of the nuclear blast can carry across the terrain 0:03:34.520 --> 0:03:38.120 to places that the US, as we'll find out in 0:03:38.120 --> 0:03:42.080 in our discussion, um that people may not necessarily have 0:03:42.160 --> 0:03:45.240 been planning on being affected. Yeah you might. You know, 0:03:45.320 --> 0:03:48.000 it's not just the immediate area. It's not a precision 0:03:48.040 --> 0:03:52.440 weapon and that Yeah, there's a precision blast area that 0:03:52.520 --> 0:03:54.680 you're that you can be pretty sure is going to 0:03:54.720 --> 0:03:57.320 be vaporized when you hit it, but then there's a 0:03:57.480 --> 0:04:01.200 large area around that. Depending upon the climate and you know, 0:04:01.280 --> 0:04:04.440 the specific weather conditions at that time, it could affect 0:04:04.800 --> 0:04:09.760 neighboring countries, you know, essentially innocent bystandards to whatever. So 0:04:09.840 --> 0:04:13.920 let's get into this. Let's talk first about atoms. Yeah, 0:04:14.040 --> 0:04:16.000 I mean, you think about it that one of the 0:04:16.040 --> 0:04:20.479 fascinating things about this is that such a devastating reaction 0:04:20.640 --> 0:04:25.279 can be caused by something as tiny as an atom. Yeah. Uh. 0:04:25.320 --> 0:04:27.920 And just so that we all have our little a 0:04:27.920 --> 0:04:30.960 little refresher course, even though I'm sure no one listening 0:04:30.960 --> 0:04:36.080 needs it. Your basic atom has a nucleus that is 0:04:36.279 --> 0:04:40.760 orbited by electrons. Now your electrons are you're negatively charged particles. Yes, 0:04:40.880 --> 0:04:45.320 your nucleus typically contains at least one proton. Actually it 0:04:45.320 --> 0:04:48.400 has to otherwise it's not an atom. So the proton 0:04:48.640 --> 0:04:52.560 is a positively charged particle, and the protons positive charge 0:04:52.560 --> 0:04:55.640 in the electrons negative charge are attracted to one another. 0:04:56.520 --> 0:05:00.120 It's pretty powerful. Now, there can also be in that 0:05:00.480 --> 0:05:05.760 nucleus a a particle that carries no charge at all, 0:05:06.600 --> 0:05:10.440 a neutron which has no charge, and neutrons kind of 0:05:10.520 --> 0:05:14.040 act like glue for protons, because you know, you've got 0:05:14.080 --> 0:05:17.680 this this nucleus that could have more than one proton. Well, 0:05:17.680 --> 0:05:21.200 the problem is that as similar charges repel one another. 0:05:22.040 --> 0:05:24.600 So if you have to possibly charged particles and try 0:05:24.640 --> 0:05:26.440 and put them close to each other, they're going to 0:05:26.440 --> 0:05:28.640 start repelling each other. Well, neutrons kind of act like 0:05:29.440 --> 0:05:32.720 a glue that that allows these protons to group together 0:05:33.480 --> 0:05:38.640 to form this nucleus. So, uh, if you've I'm getting 0:05:38.640 --> 0:05:40.120 out of here. No, no, don't No, it's all right. 0:05:40.240 --> 0:05:44.000 That's all right. Now you can change the number of 0:05:44.040 --> 0:05:48.200 neutrons that are within an atom. And if you do that, uh, 0:05:48.440 --> 0:05:51.800 you know, atoms have typically they have a number of 0:05:51.800 --> 0:05:55.479 neutrons that you will naturally find within the atoms of 0:05:55.520 --> 0:05:59.320 that element. Uh. If you find something that's outside of 0:05:59.320 --> 0:06:03.599 that that either is gut either has more fewer neutrons, 0:06:03.680 --> 0:06:08.480 it's an isotope. So isotopes of atoms are atoms that 0:06:08.760 --> 0:06:11.719 contain a different number of neutrons than you would typically 0:06:11.760 --> 0:06:15.520 find them in nature. Plus, isotopes are a baseball team 0:06:15.520 --> 0:06:19.760 in springfield. That's also true. Now this is not to 0:06:19.800 --> 0:06:23.440 be confused with ions. And ion is an atom that 0:06:23.480 --> 0:06:26.120 has either gained or lost in electron, and so it 0:06:26.320 --> 0:06:30.440 either has a positive charge or a negative charge because 0:06:30.480 --> 0:06:33.240 of that. So of course if it's gained an electron, 0:06:33.279 --> 0:06:36.040 then overall the atom has a negative charge if it's 0:06:36.040 --> 0:06:38.400 lost in electron and overall the atom has a positive charge. 0:06:39.120 --> 0:06:43.000 So that's the difference between ions and isotopes. Now isotopes 0:06:43.080 --> 0:06:48.080 really that's what ends up being important in these nuclear weapons. 0:06:48.080 --> 0:06:51.280 It's it's sort of a key feature. Um. Another thing 0:06:51.279 --> 0:06:54.159 that's that's important to note is that for the most part, 0:06:54.279 --> 0:06:57.320 atoms are pretty stable. Yes, I mean, once you get 0:06:57.360 --> 0:07:01.120 them in their natural state, they're unlikely to change all 0:07:01.160 --> 0:07:05.039 that much. They don't uh, randomly shed electrons or the 0:07:05.040 --> 0:07:07.440 things unless some force acts on them. They just sort 0:07:07.440 --> 0:07:11.480 of go along there about their business and stick to themselves, right, 0:07:11.480 --> 0:07:14.239 because if they were if they were unstable, they would 0:07:14.320 --> 0:07:17.440 very they would not necessarily very quickly. But if they 0:07:17.480 --> 0:07:21.760 were unstable, they would change to become more stable over time. 0:07:21.800 --> 0:07:25.440 That's what we call decay. So if you have an 0:07:25.480 --> 0:07:30.160 atom that is unstable, it will eventually change to a 0:07:30.240 --> 0:07:32.600 more stable form. And in the process of that, it's 0:07:32.600 --> 0:07:35.720 going to give up some energy, uh, and it can 0:07:35.760 --> 0:07:39.600 give up energy and in multiple ways. There's actually three 0:07:39.720 --> 0:07:45.440 main types of radioactive decay, that's right. There's alpha decay, 0:07:45.600 --> 0:07:48.120 which is where you've got your nucleus and it it's 0:07:48.120 --> 0:07:51.640 going to kick out two protons and two neutrons bound together, 0:07:52.120 --> 0:07:55.720 which is also called an alpha particle. Then you've got 0:07:55.840 --> 0:08:00.600 beta decay. And this is where a neutron actually changes 0:08:00.760 --> 0:08:05.760 becomes a proton. Uh. Then the neutron or the proton, 0:08:05.880 --> 0:08:09.800 and the an electron and an anti anti neutrino are 0:08:09.840 --> 0:08:13.080 all ejected together. That's the beta particle, or actually the 0:08:13.080 --> 0:08:17.000 ejected electron is the beta particles specifically UM. So, yeah, 0:08:17.160 --> 0:08:20.720 good all anti newtrinos I tell you they they go 0:08:20.800 --> 0:08:24.280 opposite the as the speed of light. So we talked 0:08:24.280 --> 0:08:26.160 about the whole new trinos whether or not they were 0:08:26.160 --> 0:08:27.560 going faster than the speed of light with a large 0:08:27.560 --> 0:08:30.560 hadron collider. Right now, it looks like they didn't. Looks 0:08:30.560 --> 0:08:34.040 like that was all due to uh, some some issues 0:08:34.080 --> 0:08:38.719 with the measuring technology looking at the scoreboard today, right, 0:08:38.880 --> 0:08:41.320 which could change by the time this podcast gets out. 0:08:41.600 --> 0:08:45.000 So the third type is spontaneous fission. Now, vision is 0:08:45.080 --> 0:08:50.720 where you have a nucleus split into two pieces. It's 0:08:50.840 --> 0:08:54.479 um the opposite of fusion. Fusion is where two nucleuses 0:08:54.559 --> 0:08:59.240 come together and join. And both vision and fusion you 0:08:59.280 --> 0:09:02.800 have a release of energy. Now for radioactive decay, we're 0:09:02.840 --> 0:09:07.400 specifically talking about fission, not fusion. So in this the 0:09:07.520 --> 0:09:12.240 nucleus splits and it might eject neutrons which can become 0:09:12.280 --> 0:09:17.840 neutron raise, and it also can emit electromagnetic energy called 0:09:18.040 --> 0:09:23.880 gamma raise, which do not talk about fantastic four. You're 0:09:23.920 --> 0:09:26.480 looking at me like I was talking about some or 0:09:26.600 --> 0:09:29.520 the Hulk. I was waiting for you to make that. 0:09:30.240 --> 0:09:32.200 Actually I think it was cosmic rays with the fantastic 0:09:32.480 --> 0:09:35.480 gamma radiation for the incredible Hulk. I don't want to 0:09:35.480 --> 0:09:40.120 get my science wrong. You're absolutely scientific. My air quotes 0:09:40.440 --> 0:09:44.480 science wrong. So yeah, gamma raise. It's interesting that they 0:09:44.480 --> 0:09:47.000 are the only type of nuclear radiation that comes from 0:09:47.120 --> 0:09:51.120 energy rather than particles. Yes, all right, I bet you 0:09:51.160 --> 0:09:53.160 learned that on how stuff Works dot com. Yes, there's 0:09:53.200 --> 0:09:55.080 a really good article about that. We we have. We 0:09:55.160 --> 0:09:56.840 have a couple of articles on how stuff Works dot 0:09:56.880 --> 0:09:59.000 Com that are going to be really useful as we 0:09:59.040 --> 0:10:02.600 talk about this, include how nuclear weapons work, how nuclear 0:10:03.320 --> 0:10:08.160 how nuclear radiation works, and also how there's an article 0:10:08.160 --> 0:10:10.720 about the Manhattan Project. We'll talk about the Manhattan Project 0:10:10.720 --> 0:10:14.160 in a little bit. So we've now got these three 0:10:14.160 --> 0:10:16.840 different forms of radioactive decay, and we know about this 0:10:16.960 --> 0:10:20.760 new the spontaneous fission. Well, what's interesting is that the 0:10:20.800 --> 0:10:24.960 fission doesn't necessarily have to be spontaneous. If you find 0:10:25.080 --> 0:10:29.360 the right kind of unstable atom and you are able 0:10:29.440 --> 0:10:34.840 to bombard it with neutrons, then sometimes those atoms will 0:10:34.920 --> 0:10:38.160 accept a neutron and in the process they will become 0:10:38.200 --> 0:10:41.600 so unstable as that the nucleus itself will split apart, 0:10:41.960 --> 0:10:44.680 and in that process the nucleus will release energy. It 0:10:44.760 --> 0:10:47.360 also may release other neutrons, which means that if you 0:10:47.400 --> 0:10:50.440 get a bunch of these unstable items together and you 0:10:50.720 --> 0:10:54.880 shoot a neutron at them, and then that first that 0:10:54.960 --> 0:10:58.839 first nucleus splits apart and more neutrons split off of it, 0:10:58.840 --> 0:11:02.280 it can cause more of these unstable atoms to do 0:11:02.320 --> 0:11:04.840 the same thing, and that's where you have a chain reaction. 0:11:05.520 --> 0:11:08.040 I can't remember who it was that had that the 0:11:08.080 --> 0:11:12.520 TV show where they had a clear plastic box and 0:11:12.600 --> 0:11:15.760 on the bottom of the box they had uh mouse traps, 0:11:16.280 --> 0:11:18.760 and each mouse traps, each mouse trap had two ping 0:11:18.800 --> 0:11:21.839 pong balls on and those represented um the stable. Actually, 0:11:21.920 --> 0:11:25.120 it's probably been done by five thousand people. Anyway. You 0:11:25.160 --> 0:11:28.480 can find clips of the same sort of thing on 0:11:28.559 --> 0:11:30.920 YouTube and then by lots of different people, and I 0:11:31.320 --> 0:11:34.640 enjoy watching it because it's really an excellent demonstration. So 0:11:34.679 --> 0:11:37.640 each of these these mouse trap atoms with its two 0:11:38.200 --> 0:11:42.040 ping pong balls represents these unstable atoms, and it's so 0:11:42.280 --> 0:11:46.760 and the ping pong balls represent the ejected neutrons exactly exactly, 0:11:46.800 --> 0:11:50.160 and so uh, somebody else will drop a ping pong 0:11:50.200 --> 0:11:54.120 ball inside a small hole in the box representing the 0:11:54.120 --> 0:11:56.720 neutron in this case that is bombarding these these atoms. 0:11:57.040 --> 0:11:59.080 And as soon as it hits one mouse trap and 0:11:59.080 --> 0:12:02.160 sets it off, the pong balls from that one fly 0:12:02.360 --> 0:12:05.640 in other directions, thereby setting off the other mouse traps. 0:12:05.840 --> 0:12:07.800 And it all happens in a very very short period 0:12:07.800 --> 0:12:09.280 of time. It takes almost no time at all for 0:12:09.320 --> 0:12:11.959 this thing for all the the mouse traps to release 0:12:12.000 --> 0:12:14.720 their part of ping pong balls. Yeah. Now, and in 0:12:14.760 --> 0:12:17.480 the case of a nuclear weapon, these reactions are happening 0:12:17.520 --> 0:12:22.040 in billions of a second. So now let's get to 0:12:22.200 --> 0:12:25.839 the actual elements that are used in nuclear weaponry. So 0:12:25.880 --> 0:12:28.960 one of them is an isotope of uranium, uranium two 0:12:29.000 --> 0:12:32.319 thirty five. That's a very complex atom. Yeah, it's got 0:12:32.400 --> 0:12:36.080 ninety two protons right, So, but it's got a hundreds 0:12:36.240 --> 0:12:40.079 forty three neutrons. And the thing about this is that 0:12:40.160 --> 0:12:43.880 it will accept a neutron. If if you bombard uranium 0:12:43.920 --> 0:12:47.160 two thirty five, it very easily will accept that neutron. 0:12:48.120 --> 0:12:51.480 Take that neutron, yeah, and then it it makes the 0:12:51.640 --> 0:12:54.560 uranium unstable, and then it will split apart like I 0:12:54.600 --> 0:12:56.760 just said in and you'll get that energy and those 0:12:57.400 --> 0:13:02.959 other neutrons released. So that the problem the problem with this, 0:13:03.640 --> 0:13:06.800 many problems with this. One of the issues that the 0:13:06.840 --> 0:13:11.680 people who first started working on nuclear weapons technology encountered 0:13:11.760 --> 0:13:14.040 was that, first of all, they weren't sure which elements 0:13:14.040 --> 0:13:17.200 were going to react this way because not all of 0:13:17.200 --> 0:13:20.680 them do, so finding the right elements was tricky. The 0:13:20.679 --> 0:13:25.720 other part is that uranium two thirty five is relatively 0:13:26.120 --> 0:13:30.439 rare compared to other isotopes of uranium. Yeah, so when 0:13:30.480 --> 0:13:34.880 you find naturally occurring uranium, the uranium two thirty five 0:13:35.200 --> 0:13:40.560 in that deposit is going to be relatively sparse, and 0:13:40.679 --> 0:13:44.440 for a nuclear weapon to work, you need about uranium 0:13:44.480 --> 0:13:48.640 two thirty five so that you have the right amount 0:13:48.800 --> 0:13:54.400 of material to perpetuate this chain reaction. Otherwise, your your 0:13:55.080 --> 0:13:59.000 atoms that are unstable, maybe too far apart from each 0:13:59.080 --> 0:14:01.800 other for or that chine reaction to really take off. 0:14:02.720 --> 0:14:06.120 Note to all the nuclear physicists who are righting, who 0:14:06.200 --> 0:14:09.040 have paused to podcast and rode in to tell us 0:14:09.080 --> 0:14:11.000 that there are other types of fuel that can be 0:14:11.080 --> 0:14:14.120 used for nuclear weapons. Yes, we know that. However we're 0:14:14.200 --> 0:14:17.240 using we're starting here, starting with uranium because that's where 0:14:17.280 --> 0:14:21.560 that's where, that's where the scientists started. Yes, plutonium also used, 0:14:21.600 --> 0:14:23.880 as well as their hydrogen bombs that we'll talk about 0:14:23.920 --> 0:14:26.520 a little bit. But even hydrogen bombs use uranium and 0:14:26.520 --> 0:14:31.360 plutonium um. It's just that they're they're using a different mechanism. 0:14:31.440 --> 0:14:36.120 They're using confusion as opposed to vision. So uranium two 0:14:36.200 --> 0:14:39.800 thirty five, you have to actually refine your your right, 0:14:39.960 --> 0:14:43.840 your uranium. Wow, I can't talk today, but yes, you 0:14:43.920 --> 0:14:50.000 must take uranium your uranium, yeah, toy boat anyway, you 0:14:50.040 --> 0:14:53.480 have to take this uranium there we got that works 0:14:53.600 --> 0:14:56.560 and refine it so that you have a higher percentage 0:14:56.560 --> 0:14:59.040 of uranium two thirty five, which is what you hear 0:14:59.040 --> 0:15:01.160 about when you when you hear about these these nations 0:15:01.240 --> 0:15:06.240 like Iran with their nuclear program, you hear about are 0:15:06.280 --> 0:15:10.600 they making uranium for power facilities or are they trying 0:15:10.600 --> 0:15:15.240 to make weaponized uranium. This is talking about the enrichment process. Yes, 0:15:15.440 --> 0:15:18.960 so if you are enriching, if you're if you're creating 0:15:19.120 --> 0:15:21.920 uranium so that you've got a section of ranim that 0:15:22.120 --> 0:15:27.920 is uranium that's indicative of a weapon, it's not. You 0:15:27.960 --> 0:15:31.200 don't need that kind of concentration for a nuclear power facility. 0:15:31.520 --> 0:15:34.480 So that's one of those things that that inspectors try 0:15:34.600 --> 0:15:38.200 to determine when they go and look at a nuclear 0:15:38.240 --> 0:15:40.880 power facility to make sure that the uranium being produced 0:15:41.440 --> 0:15:46.960 is not weapons grade uranium. So anyway, that's the basis, 0:15:47.040 --> 0:15:51.720 that's the basic science behind the fission part of nuclear weapons. 0:15:51.760 --> 0:15:54.840 Will get into fusion in a second. So how did 0:15:54.880 --> 0:15:58.200 this all come about? Well, first we have to look 0:15:58.200 --> 0:16:02.040 at a fellow named Einstein. Now, Einstein came up with 0:16:02.080 --> 0:16:07.680 that famous equation E equals MC squared the theory of relativity, 0:16:07.720 --> 0:16:12.000 which states that energy is equal to mass times the 0:16:12.080 --> 0:16:14.760 speed of light squared the constant of the speed of 0:16:14.880 --> 0:16:18.520 light through a vacuum. As it turns out, so that 0:16:18.600 --> 0:16:22.680 means that you take the you take a unit of mass, 0:16:23.200 --> 0:16:25.560 you multiply it by the square of the speed of 0:16:25.640 --> 0:16:30.480 light speed light squared rather and and then that's how 0:16:30.560 --> 0:16:34.000 much energy you get from that mass. So this tells 0:16:34.080 --> 0:16:36.360 us that a tiny little bit of mass could equate 0:16:36.400 --> 0:16:39.000 to an enormous amount of energy because you're multiplying that 0:16:39.000 --> 0:16:44.840 that unit of mass against a huge number. Well, that 0:16:45.040 --> 0:16:48.680 starts leading people to think, well, this is true, then 0:16:48.720 --> 0:16:52.280 there should be some way to tap into the stuff 0:16:52.320 --> 0:16:55.600 that's around us and get at huge amounts of energy. 0:16:55.960 --> 0:16:58.080 And you had a lot of really really smart people 0:16:58.080 --> 0:17:00.720 working on this, and most of them were probably at 0:17:00.760 --> 0:17:03.160 least initially working on this is the way of finding 0:17:03.160 --> 0:17:08.080 a new energy source, not necessarily a weapon. However, World 0:17:08.160 --> 0:17:12.880 War Two really helped push the the the the research 0:17:13.000 --> 0:17:16.000 towards finding a way of using this in a military 0:17:16.000 --> 0:17:22.160 application as opposed to to just a power generation alternative. 0:17:23.119 --> 0:17:26.480 So then we go up to the nineteen thirties. You've 0:17:26.480 --> 0:17:31.240 got a fellow named Enrico firm me and he support 0:17:31.320 --> 0:17:34.840 on him in grade school. He's the one who discovered 0:17:34.880 --> 0:17:39.040 that if you were to shoot neutrons at atoms, you 0:17:39.040 --> 0:17:43.520 could sometimes form new elements, and they were including ones 0:17:43.560 --> 0:17:45.840 that just did not show up on the periodic table 0:17:45.880 --> 0:17:49.000 at all. So most of these are are atoms that 0:17:49.040 --> 0:17:52.760 are so unstable that you know, they almost immediately decay. 0:17:52.800 --> 0:17:56.240 But uh that he discovered that. And then a few 0:17:56.280 --> 0:17:59.159 years later a pair of German scientists Otto Han and 0:17:59.240 --> 0:18:04.119 Fritz straw Sman discovered that by bombarding uranium with neutrons 0:18:04.480 --> 0:18:08.080 that they could create cause the uranium atoms to split. 0:18:08.800 --> 0:18:11.959 So they're the ones who actually connected the concept of 0:18:12.000 --> 0:18:18.359 fission with shooting neutrons at an isotope and uh it 0:18:18.400 --> 0:18:21.240 actually created a radioactive barium isotope once they did that, 0:18:21.280 --> 0:18:23.440 and that's how they discovered, oh, you know, this is 0:18:23.480 --> 0:18:26.439 what happens if you do this, then you have a 0:18:26.440 --> 0:18:29.240 couple of other There are so many famous names that 0:18:29.280 --> 0:18:32.480 we could mention that worked on this, but Neil's Bore 0:18:32.560 --> 0:18:36.600 and John Wheeler started to theorize that if you were 0:18:36.640 --> 0:18:39.880 to create a fission reaction within enough of this material, 0:18:40.040 --> 0:18:43.880 you could cause a chain reaction, and if you were 0:18:43.920 --> 0:18:46.200 to contain this in some way, you could have a 0:18:46.960 --> 0:18:51.560 controlled nuclear reaction which would generate huge amounts of energy. Uh. Now, 0:18:51.800 --> 0:18:56.719 a controlled nuclear reaction could allow you to have uh power, 0:18:57.040 --> 0:18:59.720 or a controlled nuclear reaction that then results in an 0:18:59.800 --> 0:19:04.280 un controlled explosion is a weapon, it's a bomb. You know, 0:19:04.320 --> 0:19:07.360 I'm sort of reminded of our our discussion of quantum computing, 0:19:07.840 --> 0:19:11.080 which also works with Adams UM. But the thing is 0:19:11.119 --> 0:19:14.480 that figuring out the predict predictability if you happen to 0:19:14.480 --> 0:19:18.000 listen to that podcast of where the particle will go 0:19:18.080 --> 0:19:22.080 and in what direction UM is not always possible. That's 0:19:22.119 --> 0:19:24.600 one of the things that makes quantum cryptography so useful. 0:19:24.640 --> 0:19:28.199 But yeah, in this case, UM, it's kind of scary 0:19:28.280 --> 0:19:30.560 because if you imagine that this this reaction is going 0:19:30.600 --> 0:19:34.000 to unleash a large amount of power, or maybe it won't. 0:19:35.320 --> 0:19:37.600 You know, that's that can be a little scary because 0:19:37.640 --> 0:19:40.240 you don't know for sure exactly what's gonna happen when 0:19:40.240 --> 0:19:42.600 you do this. Is which is why UM. You know, 0:19:42.880 --> 0:19:47.040 they started doing experiments like you know, Columbia University in 0:19:48.560 --> 0:19:50.800 UM up in New York. They starting to mess around 0:19:50.800 --> 0:19:52.200 with this to see if they can make it work. 0:19:52.680 --> 0:19:56.160 University of Chicago squash court. Yes, yes, now that's funny 0:19:56.200 --> 0:20:01.199 because of underground underneath the fame stag field there at 0:20:01.200 --> 0:20:05.080 the University of Chicago. UM they were Enrico Fermi finally 0:20:05.080 --> 0:20:09.919 got it to work in controlled situation. UM. So you know, again, 0:20:10.960 --> 0:20:13.480 what what if it weren't controlled that might have been 0:20:13.520 --> 0:20:16.439 a little scary, but uh, you know, he got it 0:20:16.480 --> 0:20:18.639 to to to do what they thought. And this this 0:20:18.760 --> 0:20:22.199 was important because um again this is they realized that 0:20:22.520 --> 0:20:27.000 this could be a seriously potent weapon that they could 0:20:27.000 --> 0:20:30.080 be building. So um they realized that if they could 0:20:30.080 --> 0:20:33.000 harness this and do this in a controlled way, you know, 0:20:33.000 --> 0:20:36.000 then they could turn it to their advantage. Um. Around 0:20:36.040 --> 0:20:40.960 the same time that work was being done on uranium 0:20:41.520 --> 0:20:45.560 uh and and nuclear fission, scientists over at the University 0:20:45.560 --> 0:20:50.960 of California at Berkeley back in one discovered a new element, 0:20:51.840 --> 0:20:55.920 element ninety four uh and they thought that this could 0:20:55.960 --> 0:21:01.040 also work as a potential fuel for nuclear chain reactions. 0:21:01.560 --> 0:21:08.840 And this element they named plutonium and named for the dog. Yes, 0:21:08.920 --> 0:21:12.199 it was named for the dog the it took it 0:21:12.240 --> 0:21:17.119 took his name for the Roman god. But yeah, it 0:21:17.200 --> 0:21:21.560 was a year later they had actually produced enough plutonium 0:21:21.600 --> 0:21:24.280 to finally do some experiments on it, because it was 0:21:24.359 --> 0:21:27.119 not something that was easily found, which I guess we 0:21:27.160 --> 0:21:31.720 should all be thankful for. Um. And they they figured 0:21:31.760 --> 0:21:36.240 out that plutonium also would undergo fission when bombarded by neutrons. 0:21:37.160 --> 0:21:41.879 You know, we should talk about the criticality of about 0:21:41.920 --> 0:21:45.639 the of the the atoms themselves, because the thing is 0:21:46.160 --> 0:21:50.080 um say, say you have your your creative mousetratched and 0:21:50.119 --> 0:21:52.280 ping pong balls. You have to make sure that nothing 0:21:52.400 --> 0:21:55.600 is going to set it off before you mean to 0:21:55.600 --> 0:21:57.960 set it off. Yeah, you don't want to have something 0:21:58.240 --> 0:22:02.880 jostle that that's some and have it all go off prematurely. 0:22:03.000 --> 0:22:05.440 And of course with a nuclear bomb, this is truly 0:22:05.600 --> 0:22:09.159 important because of the the just the enormous amount of 0:22:09.240 --> 0:22:13.600 damage that it could it could, it could cause. We 0:22:13.680 --> 0:22:16.280 have more to say in this classic episode of tech stuff, 0:22:16.320 --> 0:22:18.800 but before we get into that, let's take a quick 0:22:18.840 --> 0:22:29.960 break to thank our sponsor. There's a couple different concepts here. 0:22:30.000 --> 0:22:34.320 There's a concept called critical mass, which is the minimum 0:22:34.359 --> 0:22:38.280 amount of mass necessary for you to have a sustain 0:22:38.440 --> 0:22:43.560 nuclear fission reaction. And then there's the subcritical mass, which 0:22:43.640 --> 0:22:48.000 is where you've got lower than that amount, And ideally 0:22:48.040 --> 0:22:50.400 what you want is to have lower than that amount 0:22:50.680 --> 0:22:54.040 up until the point where you actually want to detonate 0:22:54.080 --> 0:22:57.840 the bomb. Yes, because that's going to keep it as 0:22:57.880 --> 0:23:01.040 safe as you can you can get it. So there 0:23:01.080 --> 0:23:04.000 were a lot of challenges in trying to find a 0:23:04.040 --> 0:23:08.280 way to create a bomb where you had the material 0:23:08.720 --> 0:23:12.240 set up as subcritical until the moment of detonation where 0:23:12.240 --> 0:23:14.920 it would convert to a critical mass so that that 0:23:15.359 --> 0:23:19.119 nuclear reaction would remain sustained within it. Otherwise your bomb 0:23:19.320 --> 0:23:23.399 would still be dangerous. So it's still emit radiation. It 0:23:23.480 --> 0:23:25.560 was still a middle lot of energy. It just wouldn't 0:23:26.160 --> 0:23:29.359 cause as much damage as it was designed to do. 0:23:29.600 --> 0:23:32.320 Right now, now, critical mass is, as Jonathan said, the 0:23:32.400 --> 0:23:37.440 minimum amount needed to to achieve the fish and reaction. Now. Uh, 0:23:37.640 --> 0:23:40.840 ideally for a for a bomb condition, if you're you're 0:23:40.880 --> 0:23:43.680 trying to do this, um, you would want the fuel 0:23:43.720 --> 0:23:46.760 to be in a supercritical mass, which basically means there's 0:23:46.760 --> 0:23:50.120 more than enough necessary to achieve the fish and reaction. 0:23:50.560 --> 0:23:55.480 Um uh you know, because in this case it just 0:23:55.560 --> 0:23:58.320 applies and plenty. You want to make sure that it's 0:23:58.320 --> 0:24:00.919 going to happen. You don't wanna, you don't want to 0:24:00.920 --> 0:24:05.239 have it where through some weird set of circumstances, just 0:24:05.280 --> 0:24:11.600 some improbable but possible outcome that the bomb that as 0:24:11.680 --> 0:24:14.719 a smaller percentage of the reactions takes place than you 0:24:14.760 --> 0:24:17.280 had anticipated, because that means that the effect is going 0:24:17.320 --> 0:24:19.959 to be smaller than you had anticipated. And if you're 0:24:19.960 --> 0:24:22.920 gonna be building something as nasty and dangerous as a 0:24:23.000 --> 0:24:27.000 nuclear weapon, you kind of want it to be effective. Yes, Yeah. 0:24:27.000 --> 0:24:30.640 The point is again to to operate it when it's 0:24:30.680 --> 0:24:33.320 going to achieve the desired effect and not before, and 0:24:33.720 --> 0:24:35.280 which is really I mean, this is where it gets 0:24:35.280 --> 0:24:37.320 hard to talk about this, because the desired effect is 0:24:37.359 --> 0:24:41.639 so mind numbingly awful. I'm trying to speak of it 0:24:41.680 --> 0:24:46.000 in any scientific, clinical sense. Yeah, it's it's a little rough. 0:24:46.160 --> 0:24:51.280 So there there are two different ways to create a 0:24:51.480 --> 0:24:58.200 supercritical mass within a fission based bomb. Uh. And actually 0:24:58.240 --> 0:25:01.400