WEBVTT - Special 200th episode! 0:00:08.480 --> 0:00:10.960 Yeah, orgey, do you know what today is? Is it 0:00:11.039 --> 0:00:13.840 a special day today? Oh my god, I can't believe 0:00:13.880 --> 0:00:18.160 your forgot? Is it your birthday? Try again? Is it 0:00:18.239 --> 0:00:24.160 the anniversary of the Higgs Boson closer? It's actually our anniversary. 0:00:24.320 --> 0:00:28.360 Today is our two hundredth episode of Daniel and Jorge 0:00:28.400 --> 0:00:32.720 Explain the Universe. Two hundred episodes. Oh my gosh, it's 0:00:32.760 --> 0:00:34.960 a lot of physics and a lot of banana jots. 0:00:35.200 --> 0:00:54.120 It's a whole universe of banana physics. Hi am orhand 0:00:54.120 --> 0:00:57.400 my cartoonists and the creator of PhD comment. Hi. I'm Daniel. 0:00:57.480 --> 0:00:59.960 I'm a particle physicist, and I know at least two 0:01:00.080 --> 0:01:02.480 hundred things about physics, and I know at least two 0:01:02.560 --> 0:01:06.280 hundred bad jokes about physics. I've made ten to the 0:01:06.319 --> 0:01:09.119 two hundred bad jokes about physics, but our editor has 0:01:09.160 --> 0:01:13.279 removed most. And Welcome to our podcast, Daniel and Jorge 0:01:13.319 --> 0:01:16.120 Explained the Universe, a production of I Heart Radio, a 0:01:16.160 --> 0:01:19.240 project we started to explain to you all the amazing 0:01:19.280 --> 0:01:21.880 and crazy things out there in the universe, all the 0:01:21.959 --> 0:01:24.960 things we do know, the facts we've learned about the universe, 0:01:25.000 --> 0:01:28.920 the secret truth that we've revealed, and also the incredible questions, 0:01:28.959 --> 0:01:31.560 the things that science still has to figure out, the 0:01:31.680 --> 0:01:34.759 questions that scientists are asking, and the questions that you 0:01:34.840 --> 0:01:37.920 are asking, the deep mysteries of the universe around us. 0:01:37.959 --> 0:01:39.840 Because it turns out that there are more than two 0:01:39.959 --> 0:01:42.399 hundred questions you can ask about the universe and more 0:01:42.440 --> 0:01:46.000 than two hundred amazing facts to learn and to discover 0:01:46.280 --> 0:01:49.240 about how this crazy cosmos works. At least that's what 0:01:49.320 --> 0:01:52.520 we've discovered in doing this podcast. We had no idea 0:01:52.760 --> 0:01:55.000 how long we could keep going on. Yeah, today is 0:01:55.040 --> 0:01:59.120 a very special episode. It's our two hundred episode. What 0:01:59.160 --> 0:02:01.480 does that make it anial? Is it like a birthday, 0:02:01.920 --> 0:02:05.320 a broadcast day at pot day? I don't know, but 0:02:05.400 --> 0:02:07.560 you know, if you look up anniversaries, like you know, 0:02:07.960 --> 0:02:11.320 the fifth anniversaries paper, and the tenth anniversary is silver 0:02:11.400 --> 0:02:14.760 or whatever, the fiftieth anniversary is diamond. There is no 0:02:14.880 --> 0:02:19.440 culturally acceptable gift for two hundredth anniversary because he's ever 0:02:19.560 --> 0:02:21.200 lasted that long. I think they give you a Nobel 0:02:21.240 --> 0:02:25.480 price if you somehow managed to celebrate two hundredth anniversary, 0:02:25.520 --> 0:02:28.040 Maybe you should be the fossil anniversary something, because you've 0:02:28.080 --> 0:02:31.920 become fossilized. But congratulations Daniel, two hundred episodes. Did you 0:02:31.960 --> 0:02:34.040 ever think we would get to two hundred episodes? No? 0:02:34.200 --> 0:02:35.880 I thought you get sick of talking to me about 0:02:35.919 --> 0:02:39.440 physics after about ten or twenty. No, congratulations to you. Also, 0:02:39.520 --> 0:02:41.320 it's been a really fun ride. And thank you to 0:02:41.480 --> 0:02:44.079 all of our listeners who have listened to us talking 0:02:44.120 --> 0:02:48.160 about science and joking about bananas and shared your goofy 0:02:48.240 --> 0:02:51.400 curiosity with us. That's really what's powered us forward. So 0:02:51.480 --> 0:02:54.519 thanks for listening, and thanks for all the feedback and support. Well, 0:02:54.560 --> 0:02:57.920 I have definitely not gotten tired of listening to amazing 0:02:57.960 --> 0:03:01.120 physics and to listen to you explain rated. Um, I 0:03:01.120 --> 0:03:04.080 feel like I could go another two hundred episodes. Let's 0:03:04.120 --> 0:03:07.119 do it. Well. In honor of our two hundredth episode, 0:03:07.280 --> 0:03:09.880 I put out a tweet asking folks what we should 0:03:09.880 --> 0:03:12.959 do to celebrate our two hundredth episode, and as usual, 0:03:13.000 --> 0:03:16.120 I put out some silly suggestions and we did a 0:03:16.120 --> 0:03:19.080 little Twitter poll. Yeah, and so Daniel asked what should 0:03:19.080 --> 0:03:21.160 we do for a two hundred episode? And the options 0:03:21.160 --> 0:03:26.480 were one, eat two hundred bananas, to answer two hundred questions, 0:03:26.919 --> 0:03:32.080 three to two hundred different accents, and number four just 0:03:32.120 --> 0:03:35.040 shut up. And explain. That's right, and clearly I was 0:03:35.080 --> 0:03:36.720 going to do the explaining, but I was hoping that 0:03:36.760 --> 0:03:40.480 you would do the bananas in the accents seems a 0:03:40.520 --> 0:03:44.320 little lopsided. Daniel, Well, you're the creative one, right. How 0:03:44.360 --> 0:03:46.800 can I eat bananas and accents at the same time? 0:03:46.880 --> 0:03:49.120 Those count as different accents, you know, like Scottish or 0:03:49.160 --> 0:03:51.680 Scottish with the banana in your mouth sound very different. 0:03:51.800 --> 0:03:54.160 It was a close pole. It was a close poll, yes, 0:03:54.200 --> 0:03:56.520 exactly what it was. It dramatic like as you saw 0:03:56.560 --> 0:03:59.800 the numbers come in. Um, well, bananas was racing to 0:03:59.880 --> 0:04:03.120 the lead in the beginning, but eventually people voted for 0:04:03.280 --> 0:04:08.040 Answer two hundred questions got about thirty five Eat two 0:04:08.160 --> 0:04:11.320 hundred bananas in second place, and you know in last 0:04:11.320 --> 0:04:13.880 place was due two hundred accidents, which I was sort 0:04:13.920 --> 0:04:15.440 of hoping for. I think we have to trust the 0:04:15.480 --> 0:04:19.040 wisdom of the crowd here and not offend two hundred 0:04:19.040 --> 0:04:23.080 countries we can. There aren't two hundred countries to offend, 0:04:23.279 --> 0:04:25.719 so that would be pretty impressive if we could offend 0:04:25.800 --> 0:04:29.000 non existing countries. Yeah. So the top option was Answer 0:04:29.080 --> 0:04:32.200 two hundred questions, which when Daniel told me, I said 0:04:32.240 --> 0:04:34.800 it was a little impractical for a fifty minute podcast, 0:04:34.839 --> 0:04:36.920 that's right. They have to be like true or false questions, 0:04:37.000 --> 0:04:38.760 or you know, yes or no, or something which wouldn't 0:04:38.800 --> 0:04:41.240 be too satisfied, right. I started to think, if we 0:04:41.360 --> 0:04:44.120 take five minutes to answer each question, that's a thousand 0:04:44.200 --> 0:04:49.719 minute episode. That's basically the next two hundred episodes. Basically, 0:04:49.839 --> 0:04:53.080 we'd be done. We could celebrate our four hundred anniversary 0:04:53.200 --> 0:04:55.960 next week. Then, well, this podcast is really accelerating the 0:04:56.000 --> 0:05:00.080 logarithmic scales. We'll be doing our four thousand one in 0:05:00.080 --> 0:05:02.560 a month, that's right. And I started looking through the 0:05:02.560 --> 0:05:05.200 list of questions we've answered over email, because I answered 0:05:05.279 --> 0:05:08.320 hundreds of questions a week from listeners, and there's a 0:05:08.320 --> 0:05:10.400 lot of common things in there. But then or I 0:05:10.480 --> 0:05:12.440 had a better idea something else we could do to 0:05:12.520 --> 0:05:15.200 celebrate our two hundredth episode. Yeah, so it's be on 0:05:15.240 --> 0:05:24.039 the podcast. We'll be asking two hundred questions, but not 0:05:24.440 --> 0:05:27.640 two hundred number of questions, but a couple of questions 0:05:27.680 --> 0:05:30.400 about the number two hundred. That's right, because while the 0:05:30.520 --> 0:05:32.640 number ten and the number one hundred, and therefore the 0:05:32.760 --> 0:05:35.719 number two hundred are really just artifacts of the number 0:05:35.760 --> 0:05:38.080 of fingers we have in the way the human mind works. 0:05:38.320 --> 0:05:41.160 It's also an interesting way to ask questions about the universe, 0:05:41.160 --> 0:05:43.880 to think about like how far away are things or 0:05:43.960 --> 0:05:46.440 what happened in certain moments of time in the universe. 0:05:46.600 --> 0:05:49.440 It gives you like a fixed window to examine the universe. 0:05:49.520 --> 0:05:54.200 We'll be asking coincidentally to two hundred questions here in 0:05:54.240 --> 0:05:57.080 the podcast, and the first question has to do with 0:05:57.120 --> 0:05:59.000 what happened at the beginning of the universe. So the 0:05:59.080 --> 0:06:02.680 question is what happened in the first two hundred micro 0:06:02.880 --> 0:06:06.640 seconds of the universe. And then later on we'll tackle 0:06:06.720 --> 0:06:09.240 the another question about with the number two hundred, which 0:06:09.279 --> 0:06:13.320 is what can we find within two hundred light years 0:06:13.320 --> 0:06:15.680 of Earth? So a little bit of time and a 0:06:15.720 --> 0:06:18.039 little bit of space, a little bit of space time, Daniel, 0:06:18.920 --> 0:06:21.040 that's right. What can you find within two hundred light 0:06:21.120 --> 0:06:23.200 years of Earth? Makes me think like, are you looking 0:06:23.240 --> 0:06:25.880 for your keys? Are they somewhere out there in space? 0:06:28.200 --> 0:06:30.760 I do lose my keys a lot, even even in 0:06:30.800 --> 0:06:33.599 a pandemic where you don't go anywhere. Somehow I managed 0:06:33.600 --> 0:06:35.360 to lose my keys like every day. Well, we'll see 0:06:35.360 --> 0:06:37.080 if we can find them, all right, we'll tackle this 0:06:37.120 --> 0:06:40.320 first question first, which is what happened in the first 0:06:40.400 --> 0:06:45.000 two hundred micro seconds of the universe. Now, two hundred microseconds, 0:06:45.040 --> 0:06:48.440 that's like, boy, that's like point to milliseconds. It's not 0:06:48.560 --> 0:06:50.640 a lot of time. But it turns out a whole 0:06:50.760 --> 0:06:53.919 lot of stuff happened in the first two hundred microseconds 0:06:53.920 --> 0:06:58.080 to the universe. Basically everything's been boring ever since. Well, 0:06:58.120 --> 0:07:01.480 two d micro seconds. That's that's shorter than a blink, right, 0:07:01.560 --> 0:07:04.760 Like a blink is maybe a couple of microseconds, a 0:07:04.760 --> 0:07:08.480 couple of milliseconds. It's a very small amount of time. Absolutely, Yeah, 0:07:08.680 --> 0:07:12.000 So a lot happened in those first microseconds. A lot happened. 0:07:12.000 --> 0:07:14.840 And one of the most interesting questions really is how 0:07:14.920 --> 0:07:18.560 you even define like moment zero. If you're gonna say, 0:07:18.640 --> 0:07:20.880 let's take a window of time from the very beginning 0:07:20.880 --> 0:07:24.160 of the universe to two d microseconds afterwards, it's interesting 0:07:24.200 --> 0:07:26.880 to think about, like how the universe expands and cools, 0:07:26.880 --> 0:07:28.560 and we'll get into all of that. But then you 0:07:28.600 --> 0:07:31.320 have to wonder, like where does T equal zero? How 0:07:31.320 --> 0:07:33.640 do you define that moment? Do we even know that 0:07:33.680 --> 0:07:37.440 there was a T equal zero? So already like anchoring 0:07:37.640 --> 0:07:40.600 the left side, the early side of that window is very, 0:07:40.720 --> 0:07:42.960 very difficult. It makes me think, like was there a 0:07:43.000 --> 0:07:46.360 T minus one or like a countdown to the universe. 0:07:46.440 --> 0:07:49.240 Nobody really knows, And the problem is that we don't 0:07:49.360 --> 0:07:51.760 think about the history of the universe in that sort 0:07:51.760 --> 0:07:54.680 of forward way because we don't really have anything to 0:07:54.760 --> 0:07:57.200 build on. We don't know what was in the beginning 0:07:57.280 --> 0:07:59.680 or when the beginning was. Usually we think about it 0:07:59.760 --> 0:08:02.360 sort of in the reverse. We look at the universe now, 0:08:03.000 --> 0:08:05.360 and we look backwards in time as we look further 0:08:05.440 --> 0:08:08.880 further out into space, right, because remember the further out 0:08:08.920 --> 0:08:11.800 in space, you look older the universe is. So we 0:08:11.840 --> 0:08:14.320 can see how the universe looked a hundred years ago, 0:08:14.360 --> 0:08:16.920 a thousand years ago, a million years ago, a billion 0:08:17.000 --> 0:08:20.440 years ago, etcetera. And we can project backwards in time. 0:08:20.840 --> 0:08:22.360 So we tend to think of the history of the 0:08:22.400 --> 0:08:26.120 universe sort of from now and running the clock backwards, 0:08:26.200 --> 0:08:28.320 and we can do it pretty well, you know, back 0:08:28.360 --> 0:08:31.480 about thirteen billion years or so, But then it gets 0:08:31.520 --> 0:08:35.040 pretty murky and we have trouble extrapolating back. We don't 0:08:35.040 --> 0:08:37.000 know if there was a T equal zero, if there 0:08:37.080 --> 0:08:39.839 was like a T equals question mark, or who knows 0:08:39.920 --> 0:08:43.440 what was happening at the very beginning. That's interesting. Now, 0:08:43.480 --> 0:08:47.040 why does the picture he get fuzzy beyond if you 0:08:47.160 --> 0:08:50.520 rewind back to more than a few hundred thousand years 0:08:50.559 --> 0:08:52.960 from what what might be the beginning of time? Like 0:08:53.000 --> 0:08:56.520 what what? What actually marks up? Well, the reason is 0:08:56.559 --> 0:08:59.320 that things change, Things get really hot and dense. Right, 0:08:59.360 --> 0:09:02.520 the overall history of the universe is cooling and expanding, 0:09:02.840 --> 0:09:04.640 and so if you run that backwards from now we 0:09:04.679 --> 0:09:08.000 have a cold, large universe. You run that backwards, things 0:09:08.080 --> 0:09:11.360 get hotter and denser. And of course you could just 0:09:11.400 --> 0:09:14.880 do that naively, like assume that the laws of physics 0:09:14.920 --> 0:09:17.880 we have learned today from our cold universe still work 0:09:17.920 --> 0:09:20.880 back then, and just run the clock backwards and you 0:09:20.920 --> 0:09:23.839 get infinite density and you call that T equal zero. 0:09:23.960 --> 0:09:26.680 You could do that, but we don't think that's right. 0:09:27.040 --> 0:09:29.880 We don't think the laws we have work anymore as 0:09:29.920 --> 0:09:33.000 things get that hot and dense, just like you know, 0:09:33.040 --> 0:09:35.440 the physics of gases is different from the physics of 0:09:35.480 --> 0:09:38.439 liquids and the physics of solids, and so things change 0:09:38.440 --> 0:09:40.680 as you get hotter and denser, and then it becomes 0:09:40.679 --> 0:09:43.800 difficult to extrapolate because we're reaching into regions that we 0:09:43.880 --> 0:09:47.880 can't see anymore and we have no experience of because 0:09:48.080 --> 0:09:51.720 there's a moment in the early universe when the universe cooled. 0:09:51.960 --> 0:09:54.360 It was a hot, dense, nastiness, will talk about it, 0:09:54.600 --> 0:09:57.640 and it cooled to a place where light could fly through. 0:09:57.679 --> 0:10:00.680 It became transparent, And that's the last moment in the 0:10:00.679 --> 0:10:03.960 early universe that we can actually see. Beyond that, we're 0:10:04.000 --> 0:10:07.560 just really sort of guessing and extrapolating and using models, 0:10:07.800 --> 0:10:10.679 but those models are very uncertain. We really don't know 0:10:10.760 --> 0:10:13.040 what we're talking about. So a lot of the details 0:10:13.080 --> 0:10:16.679 we'll talk through today in this episode are really speculative. 0:10:16.679 --> 0:10:19.199 They're like, maybe it was this, and maybe it was that, 0:10:19.320 --> 0:10:22.920 and under various assumptions which seemed reasonable but could be 0:10:23.000 --> 0:10:27.000 totally wrong. You know, maybe this happened, But it's really guesswork. 0:10:27.120 --> 0:10:30.800 Is it guesswork because we don't know, like our simulations 0:10:30.960 --> 0:10:34.600 don't aren't very definitive, or like the physics of the 0:10:34.720 --> 0:10:37.719 universe might actually change it in those kind of conditions. 0:10:37.760 --> 0:10:39.880 We don't know how the physics of the universe operates 0:10:39.880 --> 0:10:42.840 in those very hot and dense environments. You know, we've 0:10:42.880 --> 0:10:46.920 only experienced it when it's pretty cold and separated, and 0:10:47.000 --> 0:10:49.680 so we're extrapolating back. We think we have ideas or 0:10:49.720 --> 0:10:52.360 how it might work, and we can simulate various ones 0:10:52.400 --> 0:10:54.600 of them, but we can't necessarily like tell the difference 0:10:54.640 --> 0:10:56.680 between if it's like this or if it's like that, 0:10:57.320 --> 0:11:00.120 and so we just we're extrapolating into the unknown, and 0:11:00.360 --> 0:11:03.080 and that's always very dangerous and delicate. Now, even the 0:11:03.120 --> 0:11:06.440 concept of time equals zero is weird, right, because I've 0:11:06.440 --> 0:11:09.480 heard people say that, you know, like it's it's almost 0:11:09.520 --> 0:11:12.960 like asking what is more north than the north Pole? 0:11:13.480 --> 0:11:15.240 Because once you get to the north pole, there's no 0:11:15.320 --> 0:11:19.080 more north? And is it the same? Also that you know, 0:11:19.120 --> 0:11:22.880 maybe time started at T equal zero and there was 0:11:22.920 --> 0:11:25.760 no time before that. It sounds bonkers to say that, right, 0:11:25.800 --> 0:11:29.600 like there was no time before that, because it's before 0:11:29.720 --> 0:11:33.000 mean if there was no time, right, It's it's confusing. 0:11:33.080 --> 0:11:35.280 It's hard to really get these ideas into your head. 0:11:35.640 --> 0:11:39.880 But it's true that some theories of the universe say 0:11:39.960 --> 0:11:44.320 that space and time were created at some moment and 0:11:44.679 --> 0:11:48.000 things have expanded and cooled since then, and before that point, 0:11:48.480 --> 0:11:51.240 there was no time, There was no space, there was 0:11:51.360 --> 0:11:55.080 no before that point. That's really hard to grasp your 0:11:55.080 --> 0:11:57.360 mind around because your mind lives in that space in 0:11:57.400 --> 0:12:00.320 that time. It's all you've experienced, and so it's all 0:12:00.360 --> 0:12:03.240 you can really imagine how you organize your thinking. It's 0:12:03.240 --> 0:12:06.440 how we think about causality and logic, and a it happens, 0:12:06.480 --> 0:12:09.160 then be happens, then see happens. But it doesn't mean 0:12:09.200 --> 0:12:12.000 it's the only way the universe can be. And so 0:12:12.080 --> 0:12:15.320 it's extraordinarily difficult to sort of extrapolate your brain and 0:12:15.320 --> 0:12:19.280 you're thinking into something completely unfamiliar, right, And so what 0:12:19.320 --> 0:12:21.959 we do is we have these frameworks like general relativity 0:12:22.000 --> 0:12:24.559 and quantum mechanics that try to tell us about what 0:12:24.720 --> 0:12:28.160 might have happened, But those aren't very conclusive either. I 0:12:28.160 --> 0:12:30.760 guess the North Pole analogy kind of works also in that, 0:12:30.960 --> 0:12:33.240 you know, like here where we are. You know, if 0:12:33.280 --> 0:12:36.280 you have like a compass, it's pretty clear how to 0:12:36.360 --> 0:12:38.560 use it, Like, you know, it tells you north and 0:12:38.640 --> 0:12:40.559 right and south and east and west, and you can 0:12:40.559 --> 0:12:42.320 walk around pretty easy blue. But if you are like 0:12:42.400 --> 0:12:44.920 near the North Pole, it might be a little tricky 0:12:45.000 --> 0:12:48.280 to use a compass, right, Yeah, if you're at the 0:12:48.320 --> 0:12:50.559 North Pole, you'd be a little disoriented. Yeah, if you're 0:12:50.559 --> 0:12:53.040 at the north pole. There is no more north to go, right, 0:12:53.120 --> 0:12:55.719 you can't go any north eier than that. But we 0:12:55.760 --> 0:12:58.200 don't know if time works that way. It could be 0:12:58.559 --> 0:13:02.120 that there was stuff for you know, these early moments, 0:13:02.160 --> 0:13:05.120 these singularities. There was a whole other universe perhaps which 0:13:05.200 --> 0:13:09.120 came down into a big crunch or something else totally different, 0:13:09.320 --> 0:13:11.839 some sort of other weird kind of thing which gave 0:13:11.880 --> 0:13:15.679 birth two hours space and time. You know, our entire universe, 0:13:15.679 --> 0:13:18.360 Our space and time could be a bubble of that 0:13:18.440 --> 0:13:22.240 other pre universe stuff like decaying into a universe. There 0:13:22.280 --> 0:13:24.640 could be a whole spectrum of other universes also that 0:13:24.679 --> 0:13:27.079 were created in the same moment, or the could that 0:13:27.120 --> 0:13:29.640 are still being created now. There could be like you know, 0:13:29.720 --> 0:13:32.360 moments of creation happening right now, really far away in 0:13:32.360 --> 0:13:36.360 this other meta space. It sounds like bonker speculation because 0:13:36.480 --> 0:13:39.480 it is mostly because we're so clueless. You mean, like now, 0:13:39.520 --> 0:13:41.680 like as we speak, there could be some time equal 0:13:41.800 --> 0:13:45.520 zero moments right now for other universes in this universe. Yeah. 0:13:45.720 --> 0:13:49.280 One idea of how our universe got started is that 0:13:49.320 --> 0:13:53.080 there was some sort of like pre universe stuff some 0:13:53.360 --> 0:13:58.320 Inflaton fields, and that our universe is essentially some random 0:13:58.360 --> 0:14:02.120 spontaneous decay of at and that's when our universe began, 0:14:02.600 --> 0:14:04.920 and that influence on Field is just like expanding and 0:14:05.000 --> 0:14:09.480 creating and eternally inflating. But all the time it's parts 0:14:09.480 --> 0:14:12.160 of it are decaying and starting whole new universes, their 0:14:12.240 --> 0:14:14.720 universes that haven't even gotten started yet, in universes that 0:14:14.760 --> 0:14:16.840 are trillions of years old. And none of this is 0:14:16.920 --> 0:14:19.840 anything we know. It's just like it's a crazy idea, 0:14:20.360 --> 0:14:22.800 and in a thousand years people will read about these 0:14:22.800 --> 0:14:25.240 ideas the way we think about, you know, the Greek's 0:14:25.320 --> 0:14:28.360 ideas about air, water, fire, and earth. We're like, well, 0:14:28.520 --> 0:14:31.280 that's cute, you know, and it could have been true. 0:14:31.360 --> 0:14:36.160 I suppose, yeah, it's it's well meaning, carefully thought out, 0:14:36.360 --> 0:14:39.320 totally wrong, And that could be the way we describe 0:14:39.400 --> 0:14:41.800 all of our current ideas about what happened to T 0:14:41.880 --> 0:14:44.200 equal zero and whether T equal zero even makes sense. 0:14:44.200 --> 0:14:48.400 It could be like cute to future busicists, exactly lessly 0:14:48.480 --> 0:14:50.960 cute to a future five year olds. Man, five year olds, 0:14:50.960 --> 0:14:53.960 and a thousand years will laugh at our ideas that 0:14:54.080 --> 0:14:58.280 were like, oh, you're ridiculous, that's silly, oh man, well, 0:14:58.440 --> 0:15:01.160 five year olds already laugh at me, Daniel, so that 0:15:01.320 --> 0:15:03.480 that's going to be We'll pretend that's on purpose though, 0:15:03.480 --> 0:15:05.880 all right, so it seems like, okay, so we can't 0:15:05.920 --> 0:15:10.200 see that well beyond a few hundred thousand years into 0:15:10.240 --> 0:15:12.840 the universe. So really asking like what happened in the 0:15:12.840 --> 0:15:17.080 first twohundred microseconds is really speculative, then that's right. All 0:15:17.120 --> 0:15:20.360 you can do is say, like, you know, extrapolate backwards 0:15:20.400 --> 0:15:23.040 from where we are it gets hotter and denser, hotter 0:15:23.080 --> 0:15:26.000 and denser, and pretend that you know how to extrapolate 0:15:26.200 --> 0:15:29.320 back to some point like general relativity says you can 0:15:29.320 --> 0:15:31.760 extrapolate all the way back to a point of infinite 0:15:31.800 --> 0:15:34.360 density and temperature. But you know, we know that general 0:15:34.400 --> 0:15:37.920 relativity is probably wrong when it talks about singularities and 0:15:37.960 --> 0:15:41.800 stuff like that, because it ignores important things like quantum mechanics, 0:15:42.040 --> 0:15:45.040 which tells us that you can't have an infinite amount 0:15:45.040 --> 0:15:47.760 of stuff in a tiny zero volume point and know 0:15:47.920 --> 0:15:51.640 all about it. So definitely something wonky happens. But you know, 0:15:51.960 --> 0:15:55.000 you can extrapolate sort of naively and say we'll call 0:15:55.080 --> 0:15:57.920 this t equal zero and we'll move forward from there. 0:15:58.280 --> 0:16:00.000 I see, I see so we're gonna plant the flow. 0:16:00.080 --> 0:16:02.280 I can say this is tequals zero, and then we're 0:16:02.280 --> 0:16:04.560 going to see what can the universe do to get 0:16:04.600 --> 0:16:07.600 us to where we are today? Kind of yeah, exactly. 0:16:07.680 --> 0:16:09.680 All right, well let's get into that and to the 0:16:09.760 --> 0:16:11.920 question of what is within two hundred light years of Earth? 0:16:12.000 --> 0:16:28.360 But first let's take a quick break. All right, Daniel, 0:16:28.560 --> 0:16:31.880 we're celebrating our two birthday. Does that mean that I'm 0:16:31.880 --> 0:16:34.120 two years old and you're two hundred years old, or 0:16:34.120 --> 0:16:36.960 we're each a hundred years old? It means we should 0:16:36.960 --> 0:16:40.640 have retired a hundred and thirty years ago. I feel 0:16:40.680 --> 0:16:43.040 like this podcast has aged me two years. I feel 0:16:43.080 --> 0:16:45.360 like I'm two hundred light years from where I started. There, 0:16:45.360 --> 0:16:47.840 you go, all right, well, so we're talking about the 0:16:47.840 --> 0:16:51.160 first two hundred microseconds of the universe, and so we'll 0:16:51.160 --> 0:16:54.200 start with time equals zero. What what happened at times zero? Daniel? 0:16:54.280 --> 0:16:56.640 We don't know, but one idea is that there was 0:16:56.680 --> 0:16:59.520 a singularity that you know, the universe was super hot 0:16:59.560 --> 0:17:01.640 and super dense. And I think a lot of people 0:17:01.720 --> 0:17:05.560 imagine this as a single point. They hear singularity to 0:17:05.640 --> 0:17:09.080 think a single point. They think one hot, dense spot 0:17:09.440 --> 0:17:12.239 like the entire energy and all the matter of the 0:17:12.320 --> 0:17:17.080 universe was in a really tiny dot. But it's better 0:17:17.119 --> 0:17:19.360 not to think about it as one place, but more 0:17:19.400 --> 0:17:21.960 to think about it as the density. Because we don't 0:17:22.000 --> 0:17:26.560 know if the universe is finite or infinite. Possible that 0:17:26.600 --> 0:17:30.000 when the universe started it was already infinite, and that 0:17:30.080 --> 0:17:36.440 this singularity we're talking about was everywhere like multiple singularity, yes, yes, precisely, 0:17:36.560 --> 0:17:39.960 like a non singular singularity. Yes. Like the singularity refers 0:17:40.160 --> 0:17:42.919 not to how many of them there were, but the 0:17:42.960 --> 0:17:46.320 fact that the density becomes infinite singularity refers to what 0:17:46.359 --> 0:17:50.000 happens to the equations, that the equations get infinities in them, 0:17:50.240 --> 0:17:53.360 because the density becomes infinite, not the size of it. 0:17:53.600 --> 0:17:56.080 And there's a i think a very common misconception that 0:17:56.080 --> 0:17:58.720 the Big Bang or pre Big Bang starts with a dot, 0:17:59.080 --> 0:18:02.040 and a dots small than an adam becomes the entire universe. 0:18:02.400 --> 0:18:04.480 And because we don't know how big the universe is, 0:18:04.480 --> 0:18:06.359 it could have been a little blob, it could have 0:18:06.359 --> 0:18:08.760 been an infinite extent. It's better to think about it 0:18:08.800 --> 0:18:12.399 in terms of infinite density, or like an infinite number 0:18:12.440 --> 0:18:15.200 of dots, an infinite number of dots. Yeah, The thing 0:18:15.240 --> 0:18:18.280 we do know is that the universe was denser and 0:18:18.359 --> 0:18:20.520 harder back then. We don't know how much of it 0:18:20.560 --> 0:18:23.119 there was, could have been infinite, could be finite, and 0:18:23.160 --> 0:18:26.040 loop all around on itself. That's a whole other episode 0:18:26.080 --> 0:18:28.639 about the size and shape of the universe, which is fascinating. 0:18:28.960 --> 0:18:30.679 But to think through the history of the universe is 0:18:30.720 --> 0:18:33.679 mostly to think about the density changing da days that 0:18:34.080 --> 0:18:37.159 you know, there's no real reason for this to exist, 0:18:37.359 --> 0:18:41.000 just somehow the universe what we know was really dance, 0:18:41.400 --> 0:18:43.600 almost like infinitely dance. Yeah, there must have been a 0:18:43.640 --> 0:18:45.879 reason for it to exist, because it does. And we 0:18:45.920 --> 0:18:48.760 think the universe follows reasons and laws. We just don't 0:18:48.800 --> 0:18:50.600 know what they are and we can't argue for it. 0:18:50.600 --> 0:18:53.160 We don't know why there was something instead of nothing, 0:18:53.200 --> 0:18:54.919 and why there was this, and could there have been 0:18:55.000 --> 0:18:58.320 other things, and you know, just really shockingly basic questions 0:18:58.560 --> 0:19:00.720 that we have really no clue about. Okay, so we 0:19:00.760 --> 0:19:04.440 had to super dance state almost infinitely dense, maybe everywhere, 0:19:04.520 --> 0:19:07.199 maybe just one dot, and then what's next thing that 0:19:07.320 --> 0:19:09.320 happened and what happened in the first tend to the 0:19:09.440 --> 0:19:11.879 minus you know, forty three seconds, so The picture you 0:19:11.880 --> 0:19:14.320 should have in your mind is that we have space, 0:19:14.840 --> 0:19:17.520 and space is really really hot, like there's a huge 0:19:17.520 --> 0:19:20.440 amount of energy. Right. The density we're really talking about 0:19:20.480 --> 0:19:24.160 there is energy density. And if you've been following the podcast, 0:19:24.200 --> 0:19:25.760 you know that we like to think about space in 0:19:25.840 --> 0:19:29.400 terms of quantum fields. Every point in space has fields 0:19:29.400 --> 0:19:33.440 in it, the electron fields of cork fields, the photon fields, etcetera. 0:19:33.800 --> 0:19:36.640 And particles that we think about today are little blobs 0:19:36.640 --> 0:19:40.000 of excitations of those fields. Today, most of those fields 0:19:40.000 --> 0:19:42.879 are very very low energy. Most of space is empty 0:19:42.880 --> 0:19:46.400 in those fields are zero. But back then, infinite density 0:19:46.440 --> 0:19:49.479 really means all those fields are going nuts. They're going crazy, 0:19:49.520 --> 0:19:53.000 they're oscillating, they're just full of energy. And so instead 0:19:53.000 --> 0:19:56.600 of thinking about individual particles, it's like having an ocean, right, 0:19:56.640 --> 0:19:59.080 you don't think about a drop of water. When you 0:19:59.119 --> 0:20:01.520 have an ocean. You can just think about the entire crazy, 0:20:01.520 --> 0:20:04.520 turbulent blob and it's doing all sorts of stuff. So 0:20:04.560 --> 0:20:07.439 the first ten to the minus forty three seconds of 0:20:07.480 --> 0:20:10.720 the universe we called this the plant epoch. Everything was 0:20:10.760 --> 0:20:12.959 hot and dense in these fields were just going crazy. 0:20:13.480 --> 0:20:16.040 Now I have a question, though, somebody's talk about that. 0:20:16.160 --> 0:20:19.640 It's not just like stuff that was crammed in together 0:20:19.720 --> 0:20:25.000 really tightly. It's also that space itself was smaller, much smaller. 0:20:26.000 --> 0:20:28.600 So it's like it's both those things. It's like everything 0:20:28.680 --> 0:20:31.959 was crowned in together and also space was smaller. That's right. 0:20:32.000 --> 0:20:34.680 There's two kinds of expansion we're gonna talk about later. 0:20:34.880 --> 0:20:38.360 One is the expansion of stuff through space as things 0:20:38.440 --> 0:20:41.520 spread out into existing space. The other is the expansion 0:20:41.880 --> 0:20:45.600 of space that you create more space, and new space 0:20:45.600 --> 0:20:48.879 itself is created. Because remember that space is not just 0:20:48.960 --> 0:20:52.600 like a backdrop on which things happen. There's a dynamical 0:20:52.640 --> 0:20:56.760 connection between space and energy. Space curves and bends and 0:20:56.800 --> 0:21:00.320 expands in response to the mass and energy that's in it, 0:21:00.720 --> 0:21:03.600 and then it shapes the motion of that mass and energy. 0:21:03.960 --> 0:21:06.639 So space and mass and energy are two things that 0:21:06.640 --> 0:21:10.280 are very tightly coupled and respond to each other. Okay, 0:21:10.440 --> 0:21:13.120 so in the first you know point zero zero zero 0:21:13.200 --> 0:21:17.840 zero down to forty zeros one seconds, you said, that's 0:21:17.880 --> 0:21:20.040