WEBVTT - How long does a neutron live? 0:00:08.440 --> 0:00:11.120 Hey, Katie, how do your particles feel today? I guess 0:00:11.119 --> 0:00:14.000 it depends on which particle you ask. All right, well, 0:00:14.080 --> 0:00:16.280 let's start with your protons. How are they feeling this morning? 0:00:16.440 --> 0:00:21.680 They're feeling pretty positive. And your electrons any negativity there? Well, 0:00:21.720 --> 0:00:25.480 I would say they're all charged up. And what about 0:00:25.480 --> 0:00:27.600 those neutrons. We don't want to overlook them? How are 0:00:27.640 --> 0:00:32.160 they doing? There? Come scums? All right, well, let's see 0:00:32.200 --> 0:00:35.320 if this podcast can get them excited. Well, I'm excited 0:00:35.360 --> 0:00:55.200 even if my neutrons are kind of just meth. Hello. 0:00:55.280 --> 0:00:58.400 I'm Daniel. I'm a particle of physicist and a professor 0:00:58.440 --> 0:01:03.000 at UC Irvine, and I contain multitudes of particles. And 0:01:03.200 --> 0:01:07.200 I am Katie Golden. I host the podcast Creature feature 0:01:07.240 --> 0:01:11.600 about animals and my particles. Uh, I think I've got 0:01:11.600 --> 0:01:16.080 at least ten of them. You know, really, your podcast 0:01:16.160 --> 0:01:19.240 is also about particles, since all animals are also made 0:01:19.240 --> 0:01:23.319 of particles. That's right, So who's the physicist? Now? We're 0:01:23.360 --> 0:01:27.920 all physicists. That's the point. Every podcast is really about particles, 0:01:28.120 --> 0:01:31.920 even those true crime podcasts, even the Bigfoot podcast, even 0:01:31.959 --> 0:01:36.160 those paranormal e sp podcasts that consistently outrank ours in 0:01:36.200 --> 0:01:42.360 the natural science category, but welcome to the podcast. Daniel 0:01:42.400 --> 0:01:45.440 and Jorge explain the universe in which we treat the 0:01:45.680 --> 0:01:49.600 entire universe as a crazy swarm of particles. Particles that 0:01:49.640 --> 0:01:53.080 are mysterious, particles that are weird, particles that follow very 0:01:53.120 --> 0:01:57.080 strange quantum rules, but particles that do follow rules in 0:01:57.120 --> 0:02:00.200 the end, rules that we think we can understand, we 0:02:00.240 --> 0:02:03.840 can digest, that we can explain to you. On this podcast, 0:02:03.840 --> 0:02:07.080 we hope to wrap our minds around everything in the universe, 0:02:07.160 --> 0:02:10.120 break it down to its time little particles, and feed 0:02:10.120 --> 0:02:13.320 them to you one by one. My co host and friend, 0:02:13.360 --> 0:02:15.480 Jorge Champ can't be here today, but we are very 0:02:15.560 --> 0:02:18.840 lucky to have our regular co host, Katie. Katie thanks 0:02:18.840 --> 0:02:21.000 a lot for joining us. Of course, I am ready 0:02:21.040 --> 0:02:26.760 to learn about particles because you know, they seem important, 0:02:27.280 --> 0:02:30.440 given that I need them in me to make me, me, 0:02:31.080 --> 0:02:34.360 to make you you. Indeed, but you know what is 0:02:34.440 --> 0:02:38.519 the units of you? Diving right into the philosophical questions 0:02:38.560 --> 0:02:40.960 at the heart of particle physics, one thing we have 0:02:41.160 --> 0:02:45.240 learned recently about particles and the universe is that we 0:02:45.280 --> 0:02:47.840 all seem to be made up of the same kinds 0:02:47.880 --> 0:02:51.519 of particles. I'm made of protons, neutrons, and electrons. You're 0:02:51.600 --> 0:02:55.280 made of protons, neutrons and electrons. What's the difference? Are 0:02:55.320 --> 0:02:59.160 there Katie particles and Daniel particles? No, it turns out 0:02:59.200 --> 0:03:02.480 that the only different it's between Daniel and Katie fundamentally, 0:03:02.639 --> 0:03:05.560 or between an apple and a banana, or between kittens 0:03:05.639 --> 0:03:09.520 and lava, is how those particles are put together. You 0:03:09.560 --> 0:03:11.680 take that same basic set of building box and you 0:03:11.680 --> 0:03:14.640 can make anything. You're blowing my mind. So if we 0:03:14.960 --> 0:03:19.160 sort of melted down Katie and Daniel into just the 0:03:19.240 --> 0:03:22.840 particles and then rearranged all the Katie particles into Daniel 0:03:22.880 --> 0:03:26.160 particle like the Daniel blueprints, then now would just create 0:03:26.200 --> 0:03:29.800 a Daniel even though uh, those were originally my particles. 0:03:30.120 --> 0:03:33.400 That's exactly right. It seems like our universe follows the 0:03:33.440 --> 0:03:37.200 same principles as legos, that the same basic building blox 0:03:37.280 --> 0:03:40.600 can be used to make anything. Right, if your little 0:03:40.640 --> 0:03:43.440 brother used your legos to make a huge dinosaur and 0:03:43.440 --> 0:03:45.600 then you smashed it and used it to build a 0:03:45.680 --> 0:03:49.440 pirate boat, you could reuse those dinosaur legos to make 0:03:49.440 --> 0:03:51.040 your pirate hip. Now Here, of course, I have to 0:03:51.120 --> 0:03:55.240 quibble with the fundamental flaw of Lego toys. The original Legos, 0:03:55.520 --> 0:03:57.640 We're just the basic building blocks, and I love that 0:03:57.720 --> 0:04:00.080 simplicity that I had no bias to them. You you 0:04:00.120 --> 0:04:03.720 could use them to make anything. These fancy new modern Legos, 0:04:03.800 --> 0:04:05.800 you know, they come with stuff printed on the sides 0:04:05.960 --> 0:04:09.400 or specific shapes, right, so the sort of like predetermine 0:04:09.480 --> 0:04:11.760 what you have to build. I'm talking about the true 0:04:11.800 --> 0:04:16.000 original Legos. Yeah. I usually just built the tallest tower 0:04:16.040 --> 0:04:18.960 I could make out of my Legos, and then usually 0:04:19.360 --> 0:04:21.720 put a bunch of guys on it, so it's like 0:04:21.800 --> 0:04:24.839 just this big tower of Babel. I don't know what 0:04:24.880 --> 0:04:27.120 that says about me, but yeah, I agree, Although I 0:04:27.160 --> 0:04:31.480 do like that modern legos do have different kinds of Legos. 0:04:31.520 --> 0:04:33.640 Like it started out, I think, with just the one 0:04:34.240 --> 0:04:37.880 Lego block unit, but now you have all sorts of 0:04:37.880 --> 0:04:41.040 different types of Legos. You have like the sort of 0:04:41.080 --> 0:04:44.760 o G blocks, but you also have these long, skinny ones, 0:04:44.839 --> 0:04:48.359 you have ones that can rotate, you have like connector legos. 0:04:48.640 --> 0:04:53.160 But is that at all similar to how the universe works? 0:04:53.400 --> 0:04:55.800 Seems to be very similar to how the universe works. 0:04:55.839 --> 0:04:58.080 You know, I'm made of protons and neutrons and electrons 0:04:58.120 --> 0:05:00.760 and store are you and so is basically everything that 0:05:00.800 --> 0:05:04.080 you've ever eaten, everything you've ever tripped over, everything you've 0:05:04.080 --> 0:05:06.479 ever thrown at your sibling. They're all made of the 0:05:06.480 --> 0:05:08.400 same ingredients. And if you look at the periodic table, 0:05:08.760 --> 0:05:11.000 you can see that that's true, right, Every element on 0:05:11.040 --> 0:05:14.359 the periodic table is just made of protons and neutrons 0:05:14.360 --> 0:05:17.840 and electrons arranged in different numbers. You start with one 0:05:17.880 --> 0:05:21.160 proton and electron, you have hydrogen. You added another proton, 0:05:21.440 --> 0:05:24.440 you get helium. Keep adding protons, do you get different elements? 0:05:24.560 --> 0:05:26.719 You're just adding more of the same basic building blocks, 0:05:26.720 --> 0:05:30.520 but you make fundamentally different elements. But those different elements 0:05:30.560 --> 0:05:34.320 are not really fundamentally different. The only difference between carbon 0:05:34.440 --> 0:05:37.880 and neon, or between lead and gold is the number 0:05:37.920 --> 0:05:41.760 of protons inside those nuclei. So really you can build 0:05:41.760 --> 0:05:44.720 anything with the same basic building blocks. It's so hard 0:05:44.800 --> 0:05:48.160 to wrap my head around that. So, you know, just 0:05:48.240 --> 0:05:51.080 like it's just seems that it's a numbers game, because 0:05:51.120 --> 0:05:54.920 like usually with legos, if you just have like five legos, 0:05:54.960 --> 0:05:57.760 it doesn't suddenly turn into from like you know, a 0:05:57.839 --> 0:06:02.080 sugar into like gold or something like that. But with 0:06:02.200 --> 0:06:06.040 these on the atomic levels. When you change just the 0:06:06.160 --> 0:06:10.840 number of these these tiny particles, it turns from you know, 0:06:10.960 --> 0:06:13.120 something that if you eat nothing would happen to you, 0:06:13.200 --> 0:06:15.200 to something if you eat it it would be bad 0:06:15.240 --> 0:06:19.680 and drive you crazy, like eating lead versus drinking air. 0:06:19.920 --> 0:06:22.160 I guess we don't really drink air, but you get 0:06:22.160 --> 0:06:25.440 the idea. Yeah. Absolutely. It might seem like a small difference. 0:06:25.560 --> 0:06:27.960 You're just adding a proton, what's the big deal, But 0:06:28.040 --> 0:06:32.280 it completely changes its emergent behavior. All these characteristics that 0:06:32.360 --> 0:06:35.880 were familiar with the way metals are shiny and conduct electricity, 0:06:36.080 --> 0:06:38.600 the way some of these elements are float around and 0:06:38.640 --> 0:06:40.800 ignore the other ones that are not very active. All 0:06:40.839 --> 0:06:44.800 of those properties are determined by how many protons and 0:06:44.960 --> 0:06:48.160 how many electrons there are in each atom, and so like, 0:06:48.200 --> 0:06:51.840 the fact that metals are metallic and conductive comes from 0:06:51.839 --> 0:06:54.400 the fact that their electron shells are not filled, which 0:06:54.440 --> 0:06:58.960 is determined by the number of protons inside the nucleus. 0:06:58.960 --> 0:07:01.599 So it's not just an relevant detail, it's a totally 0:07:01.640 --> 0:07:04.760 determining fact. But it's fascinating they're all made out of 0:07:04.760 --> 0:07:07.760 the same bits. The other fascinating thing to me is 0:07:07.839 --> 0:07:10.360 that we're all made out of roughly the same ratios 0:07:10.360 --> 0:07:13.280 of bits, Like any given atom has basically a one 0:07:13.360 --> 0:07:16.960 to one to one proton to neutron to electron ratio. 0:07:17.160 --> 0:07:20.880 So lead has more protons than hydrogen, but it also 0:07:20.920 --> 0:07:24.080 has more neutrons and also has more electrons. That means 0:07:24.120 --> 0:07:25.800 that not only are we all made out of the 0:07:25.840 --> 0:07:28.520 same three basic building blocks, but we're made out of 0:07:28.520 --> 0:07:31.440 them in the same proportions. It's not like Katie has 0:07:31.440 --> 0:07:34.160 more electrons and Daniel has more protons, right, where the 0:07:34.200 --> 0:07:38.120 same building blocks in the same proportions just rearranged differently. 0:07:38.360 --> 0:07:43.440 So you you mentioned that the number of protons sort 0:07:43.440 --> 0:07:46.080 of changes the element. In the number of electrons, it's 0:07:46.160 --> 0:07:49.720 kind of changes the characteristic of these elements, But you 0:07:49.760 --> 0:07:54.200 didn't mention neutrons too much being sort of the determinant 0:07:54.320 --> 0:07:58.680 of what these elements are. Why are neutrons different in 0:07:58.800 --> 0:08:01.960 terms of pro tons and electrons. Yeah, it's a good point, 0:08:01.960 --> 0:08:05.120 and neutrons are sadly often overlooked, which is why we 0:08:05.160 --> 0:08:08.840 are dedicating almost our entire podcast today to talking about 0:08:08.840 --> 0:08:12.520 these mysterious, funny particles. But you're right that neutrons don't 0:08:12.520 --> 0:08:16.000 really determine as much the identity of the atom, and 0:08:16.000 --> 0:08:18.880 that's because they are electrically neutral. Like if you add 0:08:18.920 --> 0:08:21.440 another proton to the atom, then in order to make 0:08:21.440 --> 0:08:24.160 it electrically neutral, you have to add another electron in 0:08:24.320 --> 0:08:28.040 orbit around it, and that really changes the chemical properties. 0:08:28.200 --> 0:08:30.840 It changes how this thing interacts, whether or not it's 0:08:30.880 --> 0:08:33.480 electron orbitals are filled, or whether it's got an opening 0:08:33.559 --> 0:08:36.040 that very strongly affects the behavior of the atom. You 0:08:36.080 --> 0:08:39.040 add another neutron, then you don't need to add another electron. 0:08:39.200 --> 0:08:41.560 So you can add neutrons, no big deal. You can't 0:08:41.559 --> 0:08:44.280 just add neutrons anytime you like to any atom. It 0:08:44.320 --> 0:08:47.079 doesn't make them heavier, and it makes these other versions 0:08:47.280 --> 0:08:50.280 of the elements. These are called isotopes. So, for example, 0:08:50.400 --> 0:08:52.760 you can have hydrogen, which is just a proton, but 0:08:52.840 --> 0:08:55.320 you can also have deuterium, which is a proton and 0:08:55.480 --> 0:08:58.280 a neutron. So you put those together inside the nucleus, 0:08:58.480 --> 0:09:01.120 you have an electron around it. It's still called hydrogen, 0:09:01.320 --> 0:09:04.120 but it's like a heavy version of hydrogen. For example, 0:09:04.120 --> 0:09:06.400 if you put that together into H two O, but 0:09:06.480 --> 0:09:08.920 instead of the hydrogen, you have this heavy version of 0:09:09.000 --> 0:09:11.480 hydrogen with a neutron also in the nucleus. Then you 0:09:11.520 --> 0:09:14.240 get what's called heavy water, which we sometimes use in 0:09:14.360 --> 0:09:16.840 nuclear experiments. Right, so it does change a little bit 0:09:16.880 --> 0:09:19.400 sort of the flavor of the element to add neutron, 0:09:19.480 --> 0:09:21.480 sort to take them away, but it doesn't change its 0:09:21.520 --> 0:09:25.240 fundamental identity, which is determined by the charged objects of 0:09:25.280 --> 0:09:28.040 proton and the electron. So that's really interesting to me. 0:09:28.640 --> 0:09:32.520 Why is the neutron involved at all in the atomic 0:09:32.559 --> 0:09:35.760 structure if it's just kind of this It seems like 0:09:35.840 --> 0:09:40.160 this neutral fluff particle just this like dead weight, But 0:09:40.400 --> 0:09:44.760 is that really true. No, the neutron often overlooked, but 0:09:44.800 --> 0:09:48.040 it does play a vital role in keeping the nucleus together. 0:09:48.080 --> 0:09:50.319 We're gonna dig into it a bit more on the podcast, 0:09:50.360 --> 0:09:53.880 but very briefly, think about how the nucleus stays together. Right, 0:09:54.000 --> 0:09:56.439 If you have the nucleus of an atom that has 0:09:56.480 --> 0:09:59.480 like twenty five protons in it, those things are all 0:09:59.559 --> 0:10:02.600 positive of lee charged. Why don't they just like bust apart? 0:10:02.920 --> 0:10:04.720 You know, why don't they repel each other because they 0:10:04.760 --> 0:10:08.280 all have the same positive charge. The answer is that 0:10:08.320 --> 0:10:11.080 the nucleus is held together by the strong force, which 0:10:11.120 --> 0:10:15.360 is much more powerful than electromagnetism and neutrons. Even though 0:10:15.400 --> 0:10:19.480 they are neutral electromagnetically, they do involve the strong force. 0:10:19.640 --> 0:10:21.840 Turns out, the nucleus is a bit of a delicate 0:10:21.880 --> 0:10:25.600 puzzle keeping those protons from flying apart. You need the neutrons. 0:10:25.600 --> 0:10:27.600 It's a little bit of a spacer, and so it's 0:10:27.640 --> 0:10:31.520 easier to make stable nuclei if you include the neutrons. 0:10:31.559 --> 0:10:35.080 I see, So without the neutrons, the protons would not 0:10:35.280 --> 0:10:38.120 be able to stand each other's presence. I know people 0:10:38.160 --> 0:10:40.959 like that and like in group dynamics, that kind of 0:10:41.080 --> 0:10:43.920 keep the peace. So that's that is really interesting. So 0:10:43.960 --> 0:10:47.120 I guess without neutrons we wouldn't exist, we would not 0:10:47.280 --> 0:10:50.760 be held together. But it's odd to me though, that 0:10:50.760 --> 0:10:55.240 that neutrons have. It seems like they're fundamentally different from 0:10:55.280 --> 0:10:57.839 like a proton or an election because they don't have 0:10:57.920 --> 0:11:01.720 this charge. So you know, how did that even really happen? Yeah, well, 0:11:01.760 --> 0:11:04.200 these are deep questions about the universe, like why do 0:11:04.240 --> 0:11:07.360 we have neutrons anyway? Right, it's just sort of how 0:11:07.400 --> 0:11:10.400 the universe coalesces. Remember, we go back to the very 0:11:10.480 --> 0:11:13.400 early part of the universe where everything is just energy, 0:11:13.440 --> 0:11:16.640 and the universe then expands and cools and as it cools. 0:11:16.679 --> 0:11:20.240 It's sort of like crystallizes into lower energy states. Things 0:11:20.280 --> 0:11:23.080 sort of like come together and form stable particles. And 0:11:23.080 --> 0:11:25.440 by looking around in the universe and seeing sort of 0:11:25.480 --> 0:11:27.640 what was made, we can tell sort of like what 0:11:27.679 --> 0:11:30.719 the options were. We don't know like why it's possible 0:11:30.760 --> 0:11:33.240 to build neutrons necessarily, but we see that a lot 0:11:33.240 --> 0:11:36.240 of them sort of emerged from the chaos of the 0:11:36.280 --> 0:11:39.360 early universe. And that's another really fascinating aspect of these 0:11:39.360 --> 0:11:43.679 particles is their age. Like protons, we think that protons 0:11:43.760 --> 0:11:47.480 probably live forever. Like you make a proton, you can 0:11:47.559 --> 0:11:50.600 just hang out forever and stick around till the end 0:11:50.679 --> 0:11:54.080 of time. Same with an electron. Electron is stable, right, 0:11:54.120 --> 0:11:56.240 you have an electron sitting in empty space, it will 0:11:56.280 --> 0:11:59.360 just stay an electron for a billion years, maybe a 0:11:59.400 --> 0:12:03.200 trillion years, a quadrillion years. And what that means is 0:12:03.240 --> 0:12:07.000 that the protons and electrons inside your body were probably 0:12:07.160 --> 0:12:10.560 made during the Big Bang. So you are made of 0:12:10.800 --> 0:12:14.640 ancient multitudes. I mean, you know, thank you for that, 0:12:14.920 --> 0:12:19.720 thank you for calling me old. So neutrons weren't necessarily 0:12:19.760 --> 0:12:22.439 made during the Big Bang. You're saying, so neutrons were 0:12:22.480 --> 0:12:25.520 also made during the Big bang, right as the universe cooled, 0:12:25.559 --> 0:12:28.160 we got protons, we've got electrons, we've got neutrons. But 0:12:28.240 --> 0:12:31.440 there's a difference between protons, electrons, and neutrons that goes 0:12:31.520 --> 0:12:35.679 beyond just their electric charge. Neutrons don't seem to last 0:12:35.760 --> 0:12:39.439 forever the same way that protons and electrons do. In fact, 0:12:39.600 --> 0:12:42.520 they don't last very long at all. So that makes 0:12:42.520 --> 0:12:47.000 them fundamentally weird and different. And by studying the details 0:12:47.000 --> 0:12:49.120 of how long the neutron lives and what it turns into, 0:12:49.200 --> 0:12:51.320 we might get some clues to these questions about like 0:12:51.600 --> 0:12:55.479 why are there neutrons after all? What's going on inside 0:12:55.480 --> 0:12:58.840 the neutrons? Are they irrelevant little particles? Are they the 0:12:58.920 --> 0:13:02.400 most important clue we have to the nature of the universe? 0:13:02.679 --> 0:13:05.120 So yeah, no, I'm really curious, like what does it 0:13:05.160 --> 0:13:08.280 mean for a neutron to be alive? And then how 0:13:08.320 --> 0:13:11.080 does it die? And how long does that process take? 0:13:11.559 --> 0:13:14.200 And so today on the podcast we'll be answering the 0:13:14.280 --> 0:13:23.079 question how long does a neutron live? Alright, Katie, and 0:13:23.080 --> 0:13:25.160 you've already called me out, I see for using the 0:13:25.200 --> 0:13:29.719 word live in the title, because our neutrons alive after all, 0:13:29.760 --> 0:13:31.959 and you know, as a particle physicist, I think about 0:13:31.960 --> 0:13:35.760 these particles as sort of having a lifetime. But you're right, 0:13:35.880 --> 0:13:38.880 neutrons are not alive, nor are they dead in any 0:13:38.880 --> 0:13:41.640 sort of biological sense. I mean, if you corner a 0:13:41.679 --> 0:13:44.400 biologist and try to get them to answer the question 0:13:44.520 --> 0:13:47.120 what is life, They're gonna start sweating and giving you 0:13:47.160 --> 0:13:50.440 a really complex answer. So it's not a simple question. 0:13:50.480 --> 0:13:52.600 But but no, I get it. So it's like a 0:13:52.720 --> 0:13:56.880 neutron does not always remain a neutron in the sense 0:13:56.920 --> 0:14:00.640 that it does not stay the same forever, and so 0:14:00.720 --> 0:14:04.520 that could be seen as it, you know, essentially decaying 0:14:04.600 --> 0:14:07.920 or dying. Right exactly, When we talk about particle lifetimes, 0:14:07.960 --> 0:14:10.719 we're talking about how long the particle exists before it 0:14:10.760 --> 0:14:14.160 turns into something else. So some particles in the universe 0:14:14.160 --> 0:14:18.160 are stable, like electrons and protons and the corks that 0:14:18.240 --> 0:14:21.640 make up those protons and photons. For example, you can 0:14:21.680 --> 0:14:24.600 create a photon with a flashlight, shoot it out into space, 0:14:24.640 --> 0:14:27.640 and it might fly for billions or trillions of years. 0:14:27.800 --> 0:14:30.600 Some of the photons received by your eyeballs when you 0:14:30.640 --> 0:14:33.920 look up at night have been crawling across the universe 0:14:34.000 --> 0:14:38.200 for billions of years. It's incredible how long they have survived. 0:14:38.520 --> 0:14:41.280 So some particles sort of live forever. And again we're 0:14:41.360 --> 0:14:45.280 using to live in a sort of anthropomorphic biological analogy 0:14:45.320 --> 0:14:49.040 to life. Really we just mean exists, but other particles don't. 0:14:49.160 --> 0:14:52.200 Other particles are not stable, and the neutron is one 0:14:52.240 --> 0:14:56.080 of those. That's really interesting. So yeah, I didn't really 0:14:56.160 --> 0:15:00.320 think of neutrons as being an impermanent thing. I think 0:15:00.360 --> 0:15:02.800 about the building blocks of life. I mean I pictured 0:15:02.800 --> 0:15:06.120 them as these like little permanent speares that you know, 0:15:06.240 --> 0:15:09.480 make everything and just stay the same, and you know 0:15:09.760 --> 0:15:13.560 that is just this kind of like solid foundation to everything. 0:15:13.560 --> 0:15:15.400 But now you're shaking that all up. What if I 0:15:15.440 --> 0:15:17.680 told you that one of your legos a specific kind 0:15:17.720 --> 0:15:19.640 of lego, if you didn't use it, it would just 0:15:19.720 --> 0:15:23.320 like evaporate or turn into other kinds of legos. That 0:15:23.400 --> 0:15:25.680 sounds like an excuse a little brother would give when 0:15:25.680 --> 0:15:28.160 you're stealing all my legos. All right, but this is 0:15:28.200 --> 0:15:32.160 not a family therapy podcast, at least not yet. So 0:15:32.240 --> 0:15:35.080 I was curious if other people had thought about the 0:15:35.160 --> 0:15:38.440 lifetime of the neutron, if people were aware that neutrons 0:15:38.440 --> 0:15:41.080 don't live forever, and how long they thought it might live. 0:15:41.200 --> 0:15:43.440 So I went out there to our cadre of Internet 0:15:43.480 --> 0:15:47.000 volunteers who are willing to answer hard physics questions without 0:15:47.040 --> 0:15:50.480 any opportunity to prepare themselves. Thank you very much, and 0:15:50.560 --> 0:15:53.560 if you would like to join this hearty group, then please, 0:15:53.600 --> 0:15:56.600 they'll be shy right to me. Two questions at Daniel 0:15:56.640 --> 0:15:59.680 and Jorge dot com. So think about it for a moment. 0:15:59.800 --> 0:16:03.360 Do you know how long a neutron lives? Here's what 0:16:03.480 --> 0:16:06.200 people had to say. I guess. My guess would be 0:16:06.320 --> 0:16:14.080 that it would live indefinitely until some other force overpowers 0:16:14.160 --> 0:16:19.240 the forces that hold it together. Tron lives um like 0:16:19.280 --> 0:16:22.720 a free nel tron shouldn't been that long, but I 0:16:22.760 --> 0:16:27.480 don't know, probably not more than a few minutes. I 0:16:27.520 --> 0:16:33.040 think that actually this is something that's really confused me 0:16:34.200 --> 0:16:38.280 as I've started to look into and tried to understand 0:16:38.760 --> 0:16:42.480 particle physics and quantum physics and everything, and I think 0:16:42.560 --> 0:16:46.600 that possibly it's just an instant. Yeah, neutrons, just like 0:16:46.600 --> 0:16:49.440 like a lot of particles, just exists for an instant. 0:16:49.680 --> 0:16:51.880 On the other hand, it could be they could last 0:16:51.960 --> 0:16:56.000 for by entire lifetime, so yeah, it could be a 0:16:56.040 --> 0:17:00.960 long time as well. Well. Neutrons makeup part of stomic nuclei, 0:17:01.560 --> 0:17:04.960 so they live for at least as long as the 0:17:05.040 --> 0:17:10.320 longest lived elements UM, so at least a few million years. 0:17:10.359 --> 0:17:14.120 But I think UH universe skills tend to be quite extreme, 0:17:14.600 --> 0:17:18.080 so I guess since they don't live for only fractions 0:17:18.200 --> 0:17:20.199 of a millisecond, I'm going to guess they live for 0:17:20.320 --> 0:17:22.840 billions of years. I don't know if a neutron lives forever, 0:17:23.040 --> 0:17:25.640 and I think the answer to that question is we 0:17:26.040 --> 0:17:29.639 don't know if neutrons live forever. I know that proton 0:17:29.720 --> 0:17:33.040 decay is still actively being studied and debated, and I 0:17:33.080 --> 0:17:36.320 don't think a neutron would be much different. And as 0:17:36.320 --> 0:17:39.480 of now, I believe we do not know how long 0:17:39.520 --> 0:17:41.639 they live or if they decay away. I know that 0:17:41.720 --> 0:17:47.640 protons decay inter neutrons UM because they emit a positron, 0:17:48.359 --> 0:17:51.240 so I'm gonna wonder whether neutrons can also emit an 0:17:51.280 --> 0:17:55.239 electron and in a sense decay into protons. But this 0:17:55.280 --> 0:17:58.560 process doesn't happen, so all the proton has a lifetime 0:17:58.880 --> 0:18:01.560 of I don't know if the order of a few 0:18:01.600 --> 0:18:05.560 seconds UM, and you'tron. I know it's a number of 0:18:05.640 --> 0:18:10.440 years and I think it's the amount amount of time 0:18:10.520 --> 0:18:13.040 is comfortable to the age of the universe something like that. 0:18:13.760 --> 0:18:17.520 I really like the answer, probably just an instant, or 0:18:17.600 --> 0:18:21.479 maybe my entire lifetime, because even though that seems funny, 0:18:21.640 --> 0:18:24.640 like how could you compare an instant to an entire lifetime? 0:18:24.680 --> 0:18:28.000 How could you be so equivocal? On the universal scale, 0:18:28.080 --> 0:18:31.560 those are almost the same in a certain way, right, 0:18:31.600 --> 0:18:35.440 Like when you look at the entire lifetime of the universe, 0:18:35.480 --> 0:18:39.719 an instant in one human lifetime or not that different exactly. 0:18:39.800 --> 0:18:42.679 And that's the incredible thing about all of these numbers 0:18:42.760 --> 0:18:45.359 in physics that when you're talking about how long something lives, 0:18:45.400 --> 0:18:49.240 it could be some crazy, tiny tiny number ten to 0:18:49.280 --> 0:18:52.199 the minus twenty seconds, or it could be cosmic the 0:18:52.240 --> 0:18:55.280 scale of the lifetime of the universe, right, which is like, 0:18:55.320 --> 0:18:58.720 you know, six tillions of seconds, and so it's hard 0:18:58.760 --> 0:19:01.640 to know, like on that huge scale where to put 0:19:01.680 --> 0:19:03.879 these numbers, And so if you don't have any information, 0:19:04.000 --> 0:19:06.840 then you're right, his entire lifetime does feel sort of 0:19:06.880 --> 0:19:09.320 like an instant. And that's one of my favorite things 0:19:09.359 --> 0:19:12.120 about physics that it may think about these cosmic sweeps 0:19:12.119 --> 0:19:15.640 of time and recognize the fact that something that might 0:19:15.640 --> 0:19:18.840 take our entire lifetime is basically meaningless on the time 0:19:18.840 --> 0:19:22.760 scale of the universe. Well, way to make me feel 0:19:22.760 --> 0:19:27.040 both old and small. So in terms of neutrons, like 0:19:27.160 --> 0:19:31.240 it is interesting, like if they live like a human lifetime, 0:19:31.720 --> 0:19:34.479 that makes me feel a little less alone, or if 0:19:34.520 --> 0:19:37.560 they live like an instant, that almost makes me feel 0:19:37.560 --> 0:19:40.879 sorry for them. It's really hard not to anthropomorphize something 0:19:40.920 --> 0:19:43.440 once we're talking about how long it lasts, as if 0:19:43.440 --> 0:19:47.200 the neutron particularly cares. But I guess I want to know, like, 0:19:47.440 --> 0:19:52.360 what what is the neutron? Should I feel sorry for it? Well, 0:19:52.400 --> 0:19:54.080 I'm not going to tell you how to feel about 0:19:54.080 --> 0:19:56.600 the particles, but I'm happy to tell you how they're 0:19:56.640 --> 0:19:58.480 put together and what they mean. And so in the 0:19:58.520 --> 0:20:00.639 case of a neutron, we've been talking about it as 0:20:00.680 --> 0:20:03.600 if it was a particle in itself, like atoms. We 0:20:03.680 --> 0:20:05.879 said are made out of protons and neutrons in the 0:20:05.960 --> 0:20:08.840 nucleus surrounded by electrons. And that's true, but we can 0:20:08.880 --> 0:20:12.359 also drill one step deeper to understand what is the 0:20:12.359 --> 0:20:15.280 neutron itself made out of? Now, in the case of 0:20:15.320 --> 0:20:18.439 some fundamental particles like the electron, we don't know if 0:20:18.480 --> 0:20:22.200 they're actually fundamental or made out of even smaller lego 0:20:22.240 --> 0:20:25.040 building blocks. So far, the electron just looks like it's 0:20:25.080 --> 0:20:27.240 only made out of itself, but that might just be 0:20:27.240 --> 0:20:29.560 because we haven't zoomed in far enough. We don't have 0:20:29.640 --> 0:20:33.240 colliders capable of blowing up electrons and seeing what's inside them. 0:20:33.240 --> 0:20:36.040 In the case of protons and neutrons, we actually have 0:20:36.200 --> 0:20:38.680 been able to break them up and see what's inside. 0:20:38.960 --> 0:20:41.000 For about the last fifty years or so, we have 0:20:41.160 --> 0:20:44.960 had colliders capable of smashing these particles and showing us 0:20:45.160 --> 0:20:47.920 what they are made out of. And fascinatingly, the proton 0:20:48.000 --> 0:20:50.680 and the neutron are made out of the same two 0:20:50.840 --> 0:20:55.000 building blocks, up quarks and down corks, so there are 0:20:55.040 --> 0:20:59.119 two funny little particles. They have weird fractional electric charges, 0:20:59.160 --> 0:21:00.879 which allows them to get added up to make a 0:21:00.920 --> 0:21:04.680 neutron or a proton. So, for example, a neutron is 0:21:04.720 --> 0:21:08.120 an up cork which is charged two thirds, and then 0:21:08.160 --> 0:21:12.359 two down corks, each of which are charged minus one third. 0:21:12.800 --> 0:21:16.480 So neutron is an up, down, down Three of these 0:21:16.480 --> 0:21:21.400 corks put together, and you get zero electric charge. So physicists, 0:21:21.880 --> 0:21:25.399 when you're asked what's up cork? Do you just say 0:21:25.640 --> 0:21:28.520 not much what's up cork with you? Or do you 0:21:28.560 --> 0:21:30.720 have an actual answer to what's an up cork? And 0:21:30.760 --> 0:21:32.840 I guess what's a down cork? I don't know what's 0:21:32.880 --> 0:21:35.600 up is down, what's down is up? Sometimes in physics, 0:21:35.680 --> 0:21:37.159 you know, as I always say, I'm not going to 0:21:37.240 --> 0:21:39.840 be held responsible for the names of these particles, but 0:21:39.960 --> 0:21:42.320 you know, there are some reasons why we called them 0:21:42.400 --> 0:21:45.320 up corks and down corks. They're organized together by the 0:21:45.359 --> 0:21:48.680 weak force into this pair, this up and down pair 0:21:48.920 --> 0:21:51.400 that get linked together by the w boson, which we're 0:21:51.400 --> 0:21:53.399 going to talk about in just a minute. But actually 0:21:53.400 --> 0:21:55.520 in the nucleus, the upcorks and down corks are not 0:21:55.640 --> 0:21:58.240 held together by the weak force. They're held together by 0:21:58.280 --> 0:22:02.320 the strong force. So quarks have electric charges, but that's 0:22:02.359 --> 0:22:05.040 not what's holding them together. Like you think about the 0:22:05.040 --> 0:22:07.560 way molecules are held together, they're held together because of 0:22:07.600 --> 0:22:10.679 the electric charges. These electrons are like whizzing around and 0:22:10.720 --> 0:22:14.080 making these ionic bonds or covalent bonds. The electric charges 0:22:14.119 --> 0:22:17.040 are basically irrelevant once you get inside the proton and 0:22:17.080 --> 0:22:20.720 the neutron because there's a much more powerful force at play. 0:22:21.040 --> 0:22:24.639 And that's the strong nuclear force, which totally overwhelms the 0:22:24.680 --> 0:22:27.879 electromagnetic force, is able to hold all of these particles together. 0:22:28.040 --> 0:22:30.680 And the strong nuclear force does that by using gluons. 0:22:31.080 --> 0:22:33.600