WEBVTT - How does carbon dating work? 0:00:08.520 --> 0:00:11.119 Hey Daniel, it's been a long time. Did you have 0:00:11.160 --> 0:00:13.600 a nice holiday with your family? We did, thank you 0:00:13.800 --> 0:00:17.479 very much. We did some of our favorite holiday traditions. Oh, 0:00:17.720 --> 0:00:20.279 like like you cooked specific meals that you only cook 0:00:20.360 --> 0:00:22.160 once a year or something like that. Well, you know, 0:00:22.280 --> 0:00:25.560 one of our favorite holiday traditions is a little bit unusual. 0:00:25.720 --> 0:00:28.520 It's trash Day, like when you roll your bins to 0:00:28.600 --> 0:00:32.159 the street because I call that Tuesday. Does that count 0:00:32.240 --> 0:00:35.080 as a holiday? CD? No? No, No. Trash Day is 0:00:35.120 --> 0:00:37.199 a much bigger deal. It's when you take all the 0:00:37.240 --> 0:00:40.200 stuff out of your closets, decide what you actually need, 0:00:40.360 --> 0:00:43.760 and donate or throw away the rest of it. Oh, 0:00:43.800 --> 0:00:46.120 I bet you find some real treasures. You know, every 0:00:46.200 --> 0:00:49.400 year we try to go one layer deeper into the 0:00:49.479 --> 0:00:53.640 archaeology of our closets. Do you think you'll ever reach 0:00:53.720 --> 0:00:57.360 the back. I'm not even convinced a back exists anymore. 0:00:57.440 --> 0:01:02.800 It might just be like an infinite stack of useless junk. Well, 0:01:02.840 --> 0:01:05.360 maybe you'll get lucky and it will have compressed for 0:01:05.480 --> 0:01:08.600 long enough that it will become diamonds or something, or 0:01:08.800 --> 0:01:10.720 be a black hole in there that'll just eat you. 0:01:11.720 --> 0:01:30.759 That's not lucky, that's less lucky. That's still interesting. Hi. 0:01:30.959 --> 0:01:34.000 I'm Daniel. I'm a professor at UC Irvine and a 0:01:34.160 --> 0:01:37.959 particle physicist, and I love throwing stuff away. I'm Kelly 0:01:38.000 --> 0:01:41.480 Wayder Smith. I'm a parasitologist with Rice University, and I 0:01:41.600 --> 0:01:45.399 love throwing stuff away. But my family doesn't know. Do 0:01:45.400 --> 0:01:49.040 you guys have arguments about how many nostalgic elements to keep? Yes, 0:01:50.600 --> 0:01:53.280 that might be the thing we argue about the most often. Actually, 0:01:53.640 --> 0:01:56.400 And are you ever right where they really need something? 0:01:56.440 --> 0:01:58.160 And you're like, Hi, you shouldn't have thrown away that 0:01:58.240 --> 0:02:01.880 melon baller. I knew we would come in Andy very rarely. 0:02:02.120 --> 0:02:04.880 And also, you know, with things like Amazon, it could 0:02:04.920 --> 0:02:06.640 show up at your house in less than a day. 0:02:06.760 --> 0:02:08.920 So even if I'm wrong, you can just get a 0:02:08.919 --> 0:02:13.240 new melon baller. That's true. Amazon has undermined your argument. 0:02:13.520 --> 0:02:15.280 That's right, That's right. You can always just use the spoon. 0:02:15.400 --> 0:02:19.400 Am I right? Well? I feel like you might appreciate 0:02:19.400 --> 0:02:22.600 the melonballer, but you'll appreciate the lack of the melonballer 0:02:22.760 --> 0:02:26.280 even more. You know, nothing is better than negative space. 0:02:26.800 --> 0:02:29.120 If you've succeeded in like cleaning out a closet or 0:02:29.120 --> 0:02:30.880 cleaning out some corner of your room, and then you 0:02:30.880 --> 0:02:34.400 can just appreciate the emptiness. I agree, I like not 0:02:34.480 --> 0:02:36.239 trimping over things in the middle of the night because 0:02:36.280 --> 0:02:37.560 I get up a lot the middle of the night. 0:02:37.680 --> 0:02:40.679 I value that well. Welcome to the podcast Daniel and 0:02:40.840 --> 0:02:44.680 Jorge Explain the Universe, in which we explore the meaning 0:02:44.760 --> 0:02:48.720 of nothingness and the very fabric of space itself. We 0:02:48.800 --> 0:02:52.160 take the whole universe apart from the junk in your closets, 0:02:52.280 --> 0:02:54.640 to the junk between your toes, to the junk that 0:02:54.760 --> 0:02:58.040 fills the whole cosmos. We want to understand it. We 0:02:58.080 --> 0:02:59.760 want to take it apart. We want to understand what 0:02:59.760 --> 0:03:01.720 it means when it's there and it's not there, and 0:03:01.840 --> 0:03:04.240 how it all got to be the way that it is. 0:03:04.440 --> 0:03:07.400 So what are we working on today? Then? Today we 0:03:07.440 --> 0:03:10.359 are thinking about the universe as a sort of mystery. 0:03:10.440 --> 0:03:13.200 I like to think of physicists as like detectives trying 0:03:13.240 --> 0:03:16.360 to crack the murder mystery of the universe, Like what 0:03:16.520 --> 0:03:19.120 happened here? We are showing up at the scene and 0:03:19.240 --> 0:03:21.880 wondering how did it all get to be the way 0:03:21.919 --> 0:03:24.320 that it is? And today you get to be the 0:03:24.400 --> 0:03:27.720 forensic scientist that dates the dead body. That's always a 0:03:27.720 --> 0:03:30.480 good character. That's right, because when you show but the scene, 0:03:30.520 --> 0:03:33.160 you want to understand what happened. You want to put 0:03:33.240 --> 0:03:35.760 things in order. You want to say, what this happened, 0:03:35.800 --> 0:03:38.200 then that happened, then the other happened, like the Solar 0:03:38.240 --> 0:03:40.680 system formed and then the Earth cooled and then life 0:03:40.680 --> 0:03:43.440 evolved on the planet, or the Big Bang happened, and 0:03:43.520 --> 0:03:46.600 then helium formed, and then much much later stars happened. 0:03:46.920 --> 0:03:49.160 The whole point of doing science is to put the 0:03:49.280 --> 0:03:52.320 universe in some sort of order. That's what a story is. 0:03:52.360 --> 0:03:55.040 And I'm a firm believer in the philosophy that human 0:03:55.080 --> 0:03:58.560 thinking is mostly about storytelling. And so in order to 0:03:58.600 --> 0:04:01.040 do that, you have to figure out why, how old 0:04:01.240 --> 0:04:04.880 is stuff, what came before what other stuff? You need 0:04:04.920 --> 0:04:07.640 to have dates and clocks and times if you're going 0:04:07.680 --> 0:04:10.600 to unravel the murder mystery of the universe. And there's 0:04:10.640 --> 0:04:12.800 a lot of different ways that we've done that throughout 0:04:12.840 --> 0:04:15.280 the years, and some of them work better for particular 0:04:15.360 --> 0:04:17.960 kinds of mysteries than others. So what sort of mysteries 0:04:18.000 --> 0:04:20.680 are we solving today? Well, of course we are interested 0:04:20.720 --> 0:04:23.440 in the mysteries of deep time. What happened in the 0:04:23.440 --> 0:04:26.159 first few moments of the universe. How long has the 0:04:26.200 --> 0:04:29.240 Earth been around? And what's been going on? How did 0:04:29.240 --> 0:04:33.160 everything come together? One of my favorite things about dating 0:04:33.240 --> 0:04:38.200 stuff is discovering those surprises, those realizations like wow, oh 0:04:38.240 --> 0:04:41.600 my gosh, the Earth is so much older than anybody 0:04:41.680 --> 0:04:45.480 ever imagined, or that the universe is shockingly old, or 0:04:45.640 --> 0:04:48.440 you know, for some people the universe might be shockingly young. 0:04:48.839 --> 0:04:51.320 Maybe some people bought the universe had been around forever 0:04:51.480 --> 0:04:54.120 or trillions of years. So anytime you get one of 0:04:54.120 --> 0:04:56.520 these dates, it's this glorious moment where you get to 0:04:56.560 --> 0:04:59.760 like pin down the universe and say, ah, now I 0:05:00.080 --> 0:05:02.800 know something about you, and that like eliminates a bunch 0:05:02.839 --> 0:05:06.640 of possibilities. When you're a reader digesting a mystery novel, 0:05:06.720 --> 0:05:08.960 you have like lots of different options in your head. 0:05:09.080 --> 0:05:10.960 Maybe it was this person, maybe it was that person, 0:05:11.040 --> 0:05:13.719 maybe it was this third person. And as you get clues, 0:05:13.800 --> 0:05:17.279 you get to eliminate possibilities, which finally reveals to you 0:05:17.520 --> 0:05:20.200 the truth, right, what actually happened in the universe. The 0:05:20.279 --> 0:05:23.200 story is revealed by elimination, and so those clues are 0:05:23.240 --> 0:05:25.800 absolutely essential. But you're right, Kelly, that there's lots of 0:05:25.800 --> 0:05:28.120 different ways to date things in the universe, and today 0:05:28.160 --> 0:05:30.920 we're gonna be focusing on something a little bit more recent, 0:05:31.360 --> 0:05:35.560 how we can use physics to understand fairly recent history 0:05:35.839 --> 0:05:39.359 here on Earth. Oh, that sounds a lot less disgusting 0:05:39.400 --> 0:05:43.960 than using flymaggots. Fly maggots, what are you talking about? 0:05:44.160 --> 0:05:47.240 That's for dating things like you know, dead bodies that 0:05:47.320 --> 0:05:49.520 you find like what stage are the fly eggs that 0:05:49.520 --> 0:05:51.320 have been laid on the body? So that's you know, 0:05:51.360 --> 0:05:53.640 we're working with like days to weeks there. So are 0:05:53.640 --> 0:05:56.400 we working on that skill or are we working like 0:05:56.560 --> 0:06:00.760 past the writing DiPT in phase. Definitely past the rotting 0:06:00.800 --> 0:06:03.000 corpse phase. But I think you put your finger on 0:06:03.040 --> 0:06:05.479 a really interesting point, which is that there are all 0:06:05.520 --> 0:06:09.560 these clocks build into nature, right like maggots take a 0:06:09.560 --> 0:06:12.760 certain amount of time to digest a corpse, or rocks 0:06:12.800 --> 0:06:15.520 take a certain amount of time to cool, and these 0:06:15.520 --> 0:06:18.159 clocks are things we can take advantage of in order 0:06:18.160 --> 0:06:21.040 to figure out how old things are, how long they've 0:06:21.080 --> 0:06:23.800 been digesting, or how long they've been cooling, or how 0:06:23.800 --> 0:06:27.000 long they've been radioactively decaying. We don't get to like 0:06:27.160 --> 0:06:29.760 design these things go back in the past and like 0:06:29.960 --> 0:06:33.280 leave clocks in place to tell us how long things took. Instead, 0:06:33.360 --> 0:06:35.880 we have to just take advantage of the clocks that 0:06:35.920 --> 0:06:38.320 we find. And some of these clocks, as you say, 0:06:38.600 --> 0:06:40.640 are really short lived, like they tell us about things 0:06:40.640 --> 0:06:42.720 that happened just for over weeks. Some of them can 0:06:42.720 --> 0:06:45.159 tell us about things that happened for billions of years, 0:06:45.240 --> 0:06:46.960 and other ones can tell us about things that happened 0:06:46.960 --> 0:06:49.800 in the last ten fifty thousand years, which is a 0:06:49.800 --> 0:06:53.520 super interesting time for the story of human civilization, how 0:06:53.600 --> 0:06:56.200 we got to be who we are. And of course, 0:06:56.240 --> 0:06:59.360 it turns out physics plays a big role. I love 0:06:59.480 --> 0:07:01.760 learning about this topic because it's so exciting to me 0:07:01.880 --> 0:07:03.920 how we figure out what tools are the best ones 0:07:03.960 --> 0:07:06.640 to use to explore the past. And I specifically like 0:07:06.720 --> 0:07:09.640 hearing about sort of physics and chemistry sorts of tools 0:07:09.880 --> 0:07:12.000 because my sense is that they're a little bit less 0:07:12.040 --> 0:07:15.840 susceptible to uncertainty. So, for example, you know, temperature can 0:07:15.880 --> 0:07:20.040 impact how fast those flies are developing. But maybe today 0:07:20.040 --> 0:07:22.320 you're going to explain to me that chemistry and physics 0:07:22.320 --> 0:07:25.640 aren't that straightforward either. It turns out to be a 0:07:25.680 --> 0:07:30.800 twisty and complicated topic. And of course sewage is involved. Yea, 0:07:33.200 --> 0:07:35.520 my wife is very happy to hear about that. And 0:07:35.640 --> 0:07:38.280 so today on the podcast, we'll be answering the question 0:07:43.400 --> 0:07:47.960 how does radiocarbon dating work? Well, should we start by 0:07:47.960 --> 0:07:51.000 seeing what the listeners think? Yes, absolutely, I was curious 0:07:51.040 --> 0:07:53.760 to hear what people had to say about this. Radiocarbon 0:07:53.840 --> 0:07:55.720 dating is something I think a lot of people have 0:07:55.960 --> 0:07:58.400 heard about. It's on television all the time, and we 0:07:58.520 --> 0:08:00.280 date this and we date that. But I was wondering 0:08:00.280 --> 0:08:03.440 if people like really understood the mechanism of it, like 0:08:03.600 --> 0:08:06.080 what the physics is of these clocks? Why is there 0:08:06.080 --> 0:08:08.240 a clock? Why does it start when you die? And 0:08:08.320 --> 0:08:10.600 how do we read it out? So thanks very much 0:08:10.600 --> 0:08:13.360 to everyone who participates in this segment of the podcast, 0:08:13.440 --> 0:08:16.200 sharing your thoughts without a chance to prepare. If you 0:08:16.240 --> 0:08:19.400 would like to participate in the future, please don't be shy. 0:08:19.560 --> 0:08:22.000 I'll be gentle. It's fun. Just write to me two 0:08:22.120 --> 0:08:25.760 questions at Daniel Njorge dot com. So before you hear 0:08:25.800 --> 0:08:29.400 these answers, think to yourself, do you know how radiocarbon 0:08:29.520 --> 0:08:33.480 dating works? Here's what people had to say. If we 0:08:33.640 --> 0:08:37.959 find some animal spoon, let's say some dinosaur spone, but 0:08:38.200 --> 0:08:41.240 it inside the Earth, and then we calculate the amount 0:08:41.240 --> 0:08:45.839 of carbon cfteen specifically present in it. Through those calculations, 0:08:45.880 --> 0:08:50.600 we can easily calculate the age of that skeleton. I've 0:08:50.640 --> 0:08:54.360 heard it get called carbon fourteen dating before, so that 0:08:54.400 --> 0:08:56.600 makes me think that it has something to do with 0:08:56.920 --> 0:09:01.400 the isotope and the decay of that carbon. Adam, you 0:09:01.480 --> 0:09:06.640 can do tet the age of organic objects by looking 0:09:06.640 --> 0:09:12.000 at the ratio of carbon isotopes. I feel like carbon 0:09:12.120 --> 0:09:19.400 dating is when like two particles of carbon or like connected. 0:09:19.880 --> 0:09:21.760 I don't know, I don't really know anything about that. 0:09:22.160 --> 0:09:24.760 I felt like the answers to these fell into two camps. 0:09:24.840 --> 0:09:26.839 People who sounded like they really knew what they were 0:09:26.840 --> 0:09:30.319 talking about and people who had maybe not even heard 0:09:30.360 --> 0:09:33.480 of carbon dating. And to me, that's it's sort of 0:09:33.600 --> 0:09:36.600 interesting that it's like an either or scenario, like maybe 0:09:36.720 --> 0:09:40.000 either you're into the kinds of TV shows that this 0:09:40.120 --> 0:09:43.680 is shown in, or maybe you're not watching and cis 0:09:43.760 --> 0:09:46.360 or what was that ship bones where the archaeologist was 0:09:46.400 --> 0:09:49.320 doing carbon fourteen dating? Yeah, what do you think? I 0:09:49.400 --> 0:09:51.520 was pretty tickled by the answer that suggested that, like 0:09:51.600 --> 0:09:54.480 carbon fourteen atoms are like hooking up. You know, they're 0:09:54.520 --> 0:09:58.440 like on Tinder, He's still finding each other and making magic. 0:09:58.840 --> 0:10:02.040 It was a clever the cuff response there. Yeah, I 0:10:02.040 --> 0:10:06.640 like our listeners are funny, funny people, absolutely, and I 0:10:06.760 --> 0:10:09.040 had a lot of fun digging into the details of this. 0:10:09.040 --> 0:10:11.320 This is not something I use in my research and 0:10:11.360 --> 0:10:13.840 so not something i'd really ever wrapped my mind around. 0:10:14.160 --> 0:10:16.640 And one of my favorite things about this podcast is 0:10:16.640 --> 0:10:18.560 that I get an excuse to go off and learn 0:10:18.600 --> 0:10:21.160 about something I always wanted to understand but never really 0:10:21.240 --> 0:10:24.080 given myself the time to dig into. So thanks for 0:10:24.120 --> 0:10:27.640 the listener who suggested this topic. How can listeners suggest 0:10:27.679 --> 0:10:30.240 topics to you? Just shoot you an email. Absolutely, if 0:10:30.280 --> 0:10:33.240 there's something you'd like to understand, please just write to 0:10:33.280 --> 0:10:36.600 me to questions at Daniel and jorhe dot com. We 0:10:36.679 --> 0:10:38.560 put it on our list and we get to every 0:10:38.559 --> 0:10:41.120 single one eventually. And I'm with you. There are a 0:10:41.120 --> 0:10:44.120 few things I enjoy more than an excuse to study 0:10:44.120 --> 0:10:47.040 a topic that's interesting that isn't part of my research program. 0:10:47.160 --> 0:10:49.080 I know, And it's weird that sometimes you feel like 0:10:49.120 --> 0:10:51.440 you need an excuse, you know, you don't just like 0:10:51.679 --> 0:10:53.400 get to slice off a few hours of your day 0:10:53.400 --> 0:10:55.880 and go read about how something works. For some reason, 0:10:55.920 --> 0:10:58.080 I feel like I have to give myself the opportunity 0:10:58.080 --> 0:11:00.640 and having to do a podcast on it, explained of 0:11:00.760 --> 0:11:03.120 the books is a good excuse to go and actually 0:11:03.200 --> 0:11:05.000 learn how something works. That is one of the weird 0:11:05.040 --> 0:11:06.920 things about academia. You don't feel like you have a 0:11:06.920 --> 0:11:09.040 lot of time to just sit and think. But I too, 0:11:09.080 --> 0:11:11.440 have created a bunch of tricks in my life, you know, like, oh, 0:11:11.440 --> 0:11:13.640 I'm going to write a book about ten emerging technology, 0:11:13.720 --> 0:11:16.079 so I have to read about all of them and 0:11:16.240 --> 0:11:19.000 so yeah, but at least we have these tricks, all right. 0:11:19.000 --> 0:11:22.520 So what is carbon fourteen? Right? So, radiocarbon dating or 0:11:22.600 --> 0:11:26.640 carbon fourteen dating uses this weird form of carbon called 0:11:26.720 --> 0:11:30.480 carbon fourteen. And when we say carbon fourteen, that number 0:11:30.600 --> 0:11:35.240 fourteen tells us how many nucleons there are in the atom. 0:11:35.320 --> 0:11:37.840 So remember that an atom has electrons around it, and 0:11:37.960 --> 0:11:41.920 in the nucleus there are protons and neutrons. Now, usually 0:11:42.040 --> 0:11:46.800 carbon has six protons and six neutrons, and so that's 0:11:46.880 --> 0:11:50.280 carbon twelve. That's like the vanilla kind of carbon, the 0:11:50.360 --> 0:11:53.200 kind that makes up most of you. And if it's 0:11:53.200 --> 0:11:55.960 in carbon dioxide, and everywhere in the atmosphere. So that's 0:11:56.000 --> 0:11:59.880 carbon twelve, which is stable. Carbon fourteen is a weird 0:12:00.240 --> 0:12:03.000 version of carbon. It's still carbon, So there are six 0:12:03.080 --> 0:12:06.840 protons inside, but there's two extra neutrons, so it's like 0:12:06.880 --> 0:12:10.240 a heavier nucleus. So that's what carbon fourteen is. And 0:12:10.320 --> 0:12:13.200 do those neutrons want to stay there or do they 0:12:13.200 --> 0:12:15.680 want to escape? So you know, the stability of the 0:12:15.800 --> 0:12:19.920 nucleus is a really interesting and complicated question. Some collections 0:12:19.920 --> 0:12:23.680 of protons and neutrons are stable. You can build carbon 0:12:23.760 --> 0:12:26.200 twelve and have it sit in space and come back 0:12:26.240 --> 0:12:29.320 a billion years later and it'll still be carbon twelve. 0:12:29.400 --> 0:12:32.520 Other constructions are not stable, Like you had two more 0:12:32.600 --> 0:12:34.760 neutrons and all of a sudden you have carbon fourteen. 0:12:34.880 --> 0:12:37.600 It's not stable. It will fall apart after a few 0:12:37.679 --> 0:12:40.320 thousand years. And this all comes down to how those 0:12:40.320 --> 0:12:43.880 protons and neutrons like to put themselves together inside the nucleus. 0:12:43.960 --> 0:12:46.640 Remember that the nucleus is only protons and neutrons, and 0:12:46.720 --> 0:12:50.520 the protons are positively charged. The neutrons are neutral, of course, 0:12:50.600 --> 0:12:52.559 and so initially you might wonder, like, well, how does 0:12:52.559 --> 0:12:56.000 the nucleus stay together anyway? It's all positive charges. Why 0:12:56.000 --> 0:12:58.440 don't they just blow each other apart? And there is 0:12:58.559 --> 0:13:01.320 that desire, right, They definitely are pushing against each other, 0:13:01.760 --> 0:13:03.920 But on the other hand, they're held together by a 0:13:04.040 --> 0:13:07.640 much stronger force. The strong nuclear force sticks the protons 0:13:07.640 --> 0:13:10.720 and the neutrons all together. So it's a delicate balance 0:13:10.760 --> 0:13:13.760 in some cases between the strong force sticking it together 0:13:13.920 --> 0:13:16.840 and the electromagnetic force trying to push it apart. You 0:13:16.840 --> 0:13:19.240 have one prototon and one neutron held together by the 0:13:19.240 --> 0:13:22.240 strong nuclear force. That's stable. And then when you've got 0:13:22.280 --> 0:13:25.120 extra neutrons floating around so that they don't pair evenly, 0:13:25.600 --> 0:13:27.760 is that what makes it unstable? Yeah, that's right. You 0:13:27.760 --> 0:13:30.760 can actually think about the construction of the nucleus in 0:13:30.800 --> 0:13:34.080 a similar way to how we think about electron orbitals. 0:13:34.440 --> 0:13:37.400 You remember learning in like high school chemistry. The electrons 0:13:37.440 --> 0:13:40.199 aren't all just buzzing around the nucleus the same way. 0:13:40.400 --> 0:13:42.920 It's like one in the lowest energy level and another 0:13:42.920 --> 0:13:44.840 one in the next energy level. They sort of fill 0:13:44.960 --> 0:13:46.760 up and they get to like more and more elaborate 0:13:46.840 --> 0:13:49.199 orbitals as they get to higher and higher energy. Well, 0:13:49.200 --> 0:13:51.800 the nucleus is constructed sort of in the same way. 0:13:52.000 --> 0:13:54.520 The picture you often have of the nucleus is just 0:13:54.600 --> 0:13:57.560 like a scoopful of protons and neutrons, But that's not 0:13:57.600 --> 0:14:01.160 really very accurate. It's more like there are shells, you're 0:14:01.200 --> 0:14:04.200 like an inner core or protons and neutrons have clicked together, 0:14:04.320 --> 0:14:06.840 and then you can surround that with another layer of 0:14:06.880 --> 0:14:10.040 like protons and neutrons, and the most stable atoms are 0:14:10.040 --> 0:14:13.640 the ones where those layers are filled. You've like clicked 0:14:13.679 --> 0:14:15.679 in all the protons and neutrons. It's sort of like 0:14:15.800 --> 0:14:18.480 making a roman arch. When you have all the bricks together, 0:14:18.679 --> 0:14:21.520 they click together to make a very stable structure. If 0:14:21.520 --> 0:14:24.520 you're just missing one, then it can be very unstable. 0:14:24.800 --> 0:14:29.240 So I didn't do great in high school chemistry? Is 0:14:29.280 --> 0:14:32.000 the reason that that sounds new to me? Because we've 0:14:32.080 --> 0:14:34.960 learned this in the twenty plus years since I've been 0:14:35.000 --> 0:14:36.760 in high school? Or is that something we usually just 0:14:36.760 --> 0:14:39.120 sort of, you know, skip over in high school, or 0:14:39.240 --> 0:14:41.840 what's the story there? How long have we known that? Well? 0:14:41.840 --> 0:14:43.520 I think we're gonna have to interview your high school 0:14:43.560 --> 0:14:45.920 chemistry teacher to really find the answer to that. Let's 0:14:46.200 --> 0:14:48.880 dig deep into your past. In fact, we have them 0:14:48.920 --> 0:14:53.000 here on the podcast Surprise Surprise is Your Life, Kelly, 0:14:53.080 --> 0:14:54.880 I don't think they like to be very much. Let's 0:14:54.880 --> 0:14:58.280 move on. No, my high school chemistry teacher would not 0:14:58.280 --> 0:15:01.920 be happy to hear from me either. I think it's 0:15:01.960 --> 0:15:04.960 a combination of both things. We have understood what's going 0:15:04.960 --> 0:15:07.600 on in the nucleus much much better in the last 0:15:07.640 --> 0:15:10.080 few decades because we've been shooting stuff at it and 0:15:10.160 --> 0:15:12.080 breaking it up and seeing what's inside of it, and 0:15:12.320 --> 0:15:15.120 it's a hard project. We've also been building heavier and 0:15:15.160 --> 0:15:18.560 heavier nuclei to understand, like what are the limits of stability? 0:15:18.800 --> 0:15:21.760 How many protons and neutrons can you stick together and 0:15:21.880 --> 0:15:24.800 have something which will stick around for billions of years. 0:15:24.880 --> 0:15:26.800 We have a whole podcast episode about what are the 0:15:26.880 --> 0:15:29.640 heaviest stable atoms And we think, for example, there might 0:15:29.680 --> 0:15:32.240 be an island of stability where you get like hundreds 0:15:32.280 --> 0:15:35.160 of protons and neutrons stuck together to make new super 0:15:35.240 --> 0:15:38.520 heavy stable elements nobody's ever seen before. So it's a 0:15:38.560 --> 0:15:40.760 complex field of study and it's probably not taught in 0:15:40.840 --> 0:15:44.480 high school chemistry because it's evolving, and also because it's messy, 0:15:44.800 --> 0:15:47.480 and I don't think that high school sophomores aren't necessarily 0:15:47.520 --> 0:15:49.400 ready for it. I'm not sure that I was ready 0:15:49.400 --> 0:15:52.480 for the electron stuff either, But all right, so these 0:15:52.480 --> 0:15:54.840 things aren't stable, and every once in a while the 0:15:54.960 --> 0:15:58.600 neutrons get picked out. How long are we talking before 0:15:58.640 --> 0:16:02.840 the neutrons get picked doubt? Does it take like weeks? Years, millennia? 0:16:03.080 --> 0:16:06.040 What are we looking at? So every atom is different. Uranium, 0:16:06.080 --> 0:16:08.480 for example, has a half life which is like the 0:16:08.560 --> 0:16:12.320 age of the Earth, but carbon fourteen only lasts about 0:16:12.400 --> 0:16:15.000 fifty seven hundred years. Now, remember when we say that, 0:16:15.040 --> 0:16:17.360 we don't mean that there's like a little clock inside 0:16:17.400 --> 0:16:20.560 every carbon and when the time expires, it dies. What 0:16:20.600 --> 0:16:22.480 we mean is that that's how long it takes, like 0:16:22.720 --> 0:16:26.680 a population of carbon atoms for half of them to decay. 0:16:27.080 --> 0:16:31.120 Each individual one might take longer or less time, because 0:16:31.160 --> 0:16:35.200 fundamentally it's a quantum mechanical effect. There's a randomness to 0:16:35.240 --> 0:16:38.560 win these things decay. So like five seven hundred years, 0:16:38.640 --> 0:16:41.120 that's much longer than any of us live. And so 0:16:41.480 --> 0:16:44.360 certainly there was no scientists who was sitting around, you know, 0:16:44.400 --> 0:16:46.800 watching these things for five thousand, seven hundred years. How 0:16:46.800 --> 0:16:49.160 do we figure something like that out? That's a great question, 0:16:49.240 --> 0:16:51.760 And you know if it did take fifty seven hundred 0:16:51.800 --> 0:16:54.840 years for every carbon atom to decay, then you couldn't 0:16:54.880 --> 0:16:57.760 measure that half life without waiting for the first one 0:16:57.800 --> 0:17:00.560 to decay, would literally take thousands of year years After 0:17:00.600 --> 0:17:03.040 one thousand years or three thousand years, you would have 0:17:03.080 --> 0:17:05.879 seen none decay, and you still wouldn't know is the 0:17:05.920 --> 0:17:09.000 half life five thousand years or five billion years right? 0:17:09.119 --> 0:17:12.600 And you wouldn't get ten year. You need a very 0:17:12.680 --> 0:17:16.640 understanding department chare that's right. And so it's the statistical 0:17:16.720 --> 0:17:19.440 nature of that, the randomness that really helps you because 0:17:19.840 --> 0:17:22.840 even though the half life is five thousand, seven hundred years, 0:17:22.880 --> 0:17:25.240 after one hundred years, there is a chance that a 0:17:25.280 --> 0:17:27.640 few of them will have decayed. So all you need 0:17:27.760 --> 0:17:31.320 is like a lot of carbon atoms, millions and billions 0:17:31.320 --> 0:17:33.679 and zillions. Unfortunately, there are a lot of them around, 0:17:33.880 --> 0:17:36.520 and you just watch for a few years or even 0:17:36.560 --> 0:17:38.760 a few months, and a few of them will decay, 0:17:38.800 --> 0:17:41.679 and from that you can extrapolate. Right as soon as 0:17:41.680 --> 0:17:43.440 you start to see some of them decay, you know 0:17:43.680 --> 0:17:45.959 how likely it is for any of them to decay, 0:17:46.119 --> 0:17:48.440 and from that you can calculate how long it would 0:17:48.480 --> 0:17:50.960 take for half of them to decay as a decay 0:17:51.000 --> 0:17:53.600 is does it go from carbon fourteen the carbon thirteen, 0:17:53.640 --> 0:17:57.000 the carbon twelves, or does it go right from fourteen 0:17:57.040 --> 0:17:59.760 to twelve? Does it lose two neutrons all in one step? 0:18:00.040 --> 0:18:04.000 So actually, carbon fourteen doesn't decay to carbon twelve. What 0:18:04.080 --> 0:18:07.679 it does when it decays is that it goes to nitrogen. 0:18:07.880 --> 0:18:13.080 Like normal nitrogen is nitrogen fourteen, but it has seven protons. 0:18:13.480 --> 0:18:16.199 So you go from something which has eight neutrons and 0:18:16.480 --> 0:18:20.240 six protons that's carbon fourteen, into something that has seven 0:18:20.320 --> 0:18:23.080 neutrons and seven protons. So you take one of the 0:18:23.119 --> 0:18:26.600 neutrons and you do a beta decay into a proton, 0:18:26.680 --> 0:18:30.879 and now carbon fourteen has flipped into nitrogen fourteen. And 0:18:30.920 --> 0:18:32.840 to me, this is really cool because this is the 0:18:32.920 --> 0:18:36.080 quantum mechanics of it. Like carbon fourteen is not totally stable, 0:18:36.119 --> 0:18:38.640 but it's also not totally unstable, like it will stick 0:18:38.680 --> 0:18:41.240 around for a long long time. It's like a particle 0:18:41.400 --> 0:18:45.159 trapped in a little potential well, and nitrogen fourteen is 0:18:45.200 --> 0:18:48.440 other state it can flip into is also a little 0:18:48.440 --> 0:18:51.680 potential well. And like classically, if you had a particle 0:18:52.000 --> 0:18:54.399 trapped in a little well, it could never get out. 0:18:54.840 --> 0:18:57.600 So what happens is that this atom switches from one 0:18:57.680 --> 0:19:00.760 state to another state even though there's like a potential 0:19:00.800 --> 0:19:04.160 barrier in between it. It does this by quantum tunneling. 0:19:04.240 --> 0:19:07.119 It's like an electron stuck in one little hole that 0:19:07.240 --> 0:19:09.359 ends up in another little hole, even though it doesn't 0:19:09.359 --> 0:19:12.119 have the energy to go over the barrier. So carbon 0:19:12.160 --> 0:19:16.639 fourteen turns into nitrogen fourteen through this random quantum mechanical 0:19:16.720 --> 0:19:19.639 tunneling process that lets a switch from one state to 0:19:19.720 --> 0:19:23.119 a lower energy state without having enough energy to actually 0:19:23.119 --> 0:19:25.840 go over the barrier in between them. That's another thing 0:19:25.840 --> 0:19:28.600 I'm amazed we ever managed to figure out. I know, 0:19:28.720 --> 0:19:31.440 so like quantum mechanics is happening all over the place 0:19:31.480 --> 0:19:35.040 in the atmosphere right in front of us. That's crazy. 0:19:35.200 --> 0:19:38.040 So where do we get carbon fourteen in the first place? Yeah, 0:19:38.119 --> 0:19:40.720 carbon fourteen only sticks around for a few thousand years. 0:19:40.720 --> 0:19:43.000 So you might wonder, like the Earth is billions of 0:19:43.080 --> 0:19:45.200 years old, why do we have a new carbon fourteen? 0:19:45.600 --> 0:19:47.560 And the only reason we do is that we have 0:19:47.600 --> 0:19:50.400 a source of it, right, this new carbon fourteen being 0:19:50.440 --> 0:19:54.440 made all the time, and of course it comes from space. 0:19:55.240 --> 0:19:58.040 The Earth is not just sitting out in empty space. 0:19:58.200 --> 0:20:02.080 Space is very far from We're being inundated with high 0:20:02.160 --> 0:20:05.480 energy particles all the time, from the Sun, from black 0:20:05.520 --> 0:20:08.920 hole accretion disks, from other galaxies. All sorts of stuff 0:20:08.920 --> 0:20:12.040 are smashing into the Earth all the time. And then 0:20:12.119 --> 0:20:14.560 we call these things cosmic rays, and when they hit 0:20:14.600 --> 0:20:18.120 the upper atmosphere, they cause all sorts of reactions. They 0:20:18.119 --> 0:20:20.960 smash into stuff and they change it. What happens is 0:20:21.240 --> 0:20:24.960 a cosmic ray will smash into like a proton that's 0:20:24.960 --> 0:20:28.359 in nitrogen, which is seven P seven N, and convert 0:20:28.400 --> 0:20:32.240 it into a neutron. So you have nitrogen fourteen smash 0:20:32.359 --> 0:20:34.640 banging with a proton, and you end up with carbon 0:20:34.720 --> 0:20:38.200 fourteen because one of those protons has gotten converted into 0:20:38.200 --> 0:20:41.800 a neutron. WHOA Okay, And that's all happening in the 0:20:41.840 --> 0:20:44.560 atmosphere and not happening much on Earth, Is that right? 0:20:44.600 --> 0:20:47.159