WEBVTT - Why Do We Have Stars? 0:00:07.160 --> 0:00:09.200 So I was outside the other night with my son 0:00:09.280 --> 0:00:11.119 looking up at the sky, and we were having a 0:00:11.119 --> 0:00:12.880 great time, and he turned to me and he asked 0:00:12.920 --> 0:00:16.760 me a question. He said, Hey, Dad, why are there stars? 0:00:17.480 --> 0:00:22.440 You mean like movie stars? No, No, why astronomical stars? 0:00:22.440 --> 0:00:24.599 He wanted to know. Wow, what did you say? Well? 0:00:24.640 --> 0:00:27.320 I thought he was asking me, like, why do stars exist? 0:00:27.440 --> 0:00:29.120 You know, why do we have bright stars in the sky. 0:00:29.240 --> 0:00:31.760 So of course I give him a long physics explanation 0:00:31.840 --> 0:00:33.720 for you know, how funion works and all this kind 0:00:33.720 --> 0:00:35.559 of stuff. I wonder what it's like to have your 0:00:35.640 --> 0:00:41.000 dad be a physics professor. It's awesome. It's awesome. I 0:00:41.320 --> 0:00:42.879 wonder how many times he's just like dad. I just 0:00:42.880 --> 0:00:48.800 wanted a one sentence answer. I once heard him explaining 0:00:48.800 --> 0:00:52.080 to his friends about black holes, and I thought, Hey, 0:00:52.400 --> 0:00:57.440 that dude is cool because of me. I think cool 0:00:57.480 --> 0:01:01.120 as might not be the appropriate adjective here. But what's 0:01:01.120 --> 0:01:04.520 the What's he satisfied with your explanation? No? Not at all. 0:01:04.600 --> 0:01:07.119 In fact, it turns out I totally misunderstood his question. 0:01:07.640 --> 0:01:09.960 When he asked why are their stars? He didn't mean 0:01:10.040 --> 0:01:12.520 like why does the star burn? He meant like, why 0:01:12.520 --> 0:01:15.039 are their stars? Plural, like why don't we just have 0:01:15.440 --> 0:01:18.440 one star? Right? Or like why isn't everything just spread 0:01:18.440 --> 0:01:21.040 out smoothly in the universe? Why does things clump together 0:01:21.080 --> 0:01:23.720 to make planets and stars and all that stuff? WHOA, 0:01:24.640 --> 0:01:27.640 That is a good question. Yeah, it's a great question. 0:01:27.640 --> 0:01:29.560 It's a kind of question kids ask, right, the kind 0:01:29.560 --> 0:01:32.160 of question you don't necessarily think to ask. It's such 0:01:32.200 --> 0:01:34.840 a basic, simple question. That's a question I have. And 0:01:34.840 --> 0:01:55.680 I'm I'm definitely not five years old. Ye I am 0:01:55.680 --> 0:01:59.120 Morhan and I'm Daniel, and welcome to our podcast, Daniel 0:01:59.160 --> 0:02:01.800 and Jorgey Wayne the Universe, in which we try to 0:02:01.840 --> 0:02:05.000 take everything or anything in the universe, even the obvious 0:02:05.040 --> 0:02:07.520 stuff like stars, and explain it to you. Why is 0:02:07.560 --> 0:02:09.480 it there? How does it work? Do I have to 0:02:09.480 --> 0:02:12.160 worry about it? Can I buy one online? We try 0:02:12.200 --> 0:02:15.600 to answer the smooth questions and also the lumpy questions. 0:02:16.840 --> 0:02:18.320 And today is going to be a bit of a 0:02:18.400 --> 0:02:21.440 lumpy episode. Today on the program, we're asking the question 0:02:26.680 --> 0:02:30.240 why are there stars? The universe has a really strange 0:02:30.360 --> 0:02:34.480 kind of shape. I mean, it's huge, but it's mostly empty, right, 0:02:34.560 --> 0:02:38.679 Like there's vast distances between stars and even vaster ones 0:02:38.720 --> 0:02:42.079 between galaxies. But then you have these hot little points, right, 0:02:42.200 --> 0:02:45.200 all this matter concentrated in these little dots. It's a 0:02:45.360 --> 0:02:48.960 really weird arrangement. Why is it concentrating these little pin points? 0:02:49.400 --> 0:02:53.000 Why isn't more diffuse or why don't all those pin 0:02:53.040 --> 0:02:55.640 points just clumped together? Yeah? Why don't we have just 0:02:55.760 --> 0:02:59.960 one mega star or like a big pudding of delute 0:03:00.080 --> 0:03:03.120 gas everywhere? Right? Why is the universe the way it 0:03:03.240 --> 0:03:05.280 is and not any of those other ways? It could 0:03:05.280 --> 0:03:08.519 have been those ways in some alternate multiverse. It probably 0:03:08.560 --> 0:03:10.720 is those ways, but in those multiverses they don't have 0:03:10.760 --> 0:03:14.079 awesome podcasts to ask this question. Yeah. Yeah, because you 0:03:14.080 --> 0:03:16.440 look at the night sky and it's beautiful, right, I 0:03:16.440 --> 0:03:19.839 mean it's it's like this black void with little white pinpoints. 0:03:20.040 --> 0:03:23.320 But you gotta wonder why does it look that way? Okay, 0:03:23.320 --> 0:03:25.360 so I have to take a digression here an artistic 0:03:25.440 --> 0:03:28.800 question for you or here, which is why do you 0:03:28.880 --> 0:03:31.960 think we find the night sky beautiful? I mean, I agree, 0:03:32.000 --> 0:03:34.200 it's gorgeous. This is the best view in the universe, right, 0:03:34.560 --> 0:03:36.680 But is it necessary do we find it beautiful to 0:03:36.760 --> 0:03:39.520 be evolved to find it beautiful? Is it just chance? Like? 0:03:39.560 --> 0:03:41.080 Could we have evolved in a way. We look up 0:03:41.080 --> 0:03:45.680 at the night stine, We're like, yuck, that's gross. M h. Well, 0:03:45.720 --> 0:03:50.160 I think we have a innate appreciation for sparkly things, right, 0:03:50.200 --> 0:03:55.200 we like we'll all pyromaniacs. Yeah, no, I mean evolved 0:03:55.200 --> 0:03:59.440 evolved from liking water maybe or being attracted to water 0:03:59.600 --> 0:04:02.920 or spark the water. I don't know, sparkling water. They 0:04:02.920 --> 0:04:07.520 had ivan then caved mondays right, Yeah, I think people 0:04:07.600 --> 0:04:09.600 used to carbonate their own water back in cave men days. 0:04:09.600 --> 0:04:12.080 I'm pretty sure that we should have asked that question 0:04:12.160 --> 0:04:13.920 Ryan North when we had him on the podcast. When 0:04:13.960 --> 0:04:18.160 did they invent sparkling water? The greatest invention all time? 0:04:18.480 --> 0:04:23.920 Sparkling water. That's a great question is why are there 0:04:24.040 --> 0:04:29.480 stars and planets as opposed to just having a monotonous, 0:04:30.640 --> 0:04:39.120 monogamous no homogeneous, monochronous, monochromatic Yeah, I mean like a 0:04:39.160 --> 0:04:41.520 plane universe. I guess why do we have stars and 0:04:41.520 --> 0:04:46.640 planets and objects and spark the objects and things rather 0:04:46.760 --> 0:04:50.800 than we're just living in a giant gas cloud. That's right. Yeah, 0:04:50.880 --> 0:04:53.279 So that's the question we're gonna try to tackle today, 0:04:53.680 --> 0:04:56.080 give you a solid answer for it. And so as 0:04:56.200 --> 0:04:59.440 usual before we answer the question we I went out 0:04:59.480 --> 0:05:02.320 and I asked bunch of unsuspecting you see, Irvine students, 0:05:02.400 --> 0:05:04.919 off the top of their head. I asked them that question. 0:05:05.120 --> 0:05:07.679 So think about it at home or wherever you're listening. 0:05:07.839 --> 0:05:10.280 Why do you think there are stars and planets and 0:05:10.360 --> 0:05:14.520 not just a smooth universe? Here's what people had to say. 0:05:14.680 --> 0:05:17.120 Why is the universe so lumpy like? Why doesn't matter 0:05:17.200 --> 0:05:19.760 just spread out totally smoothly and evenly through the universe. 0:05:20.279 --> 0:05:23.599 I want to say gravity, because there's like a certain 0:05:23.680 --> 0:05:28.120 kind of gravity putting things in place. And I have 0:05:28.320 --> 0:05:32.760 no idea. Okay, gravity, it's a result of the big bank. 0:05:32.960 --> 0:05:36.599 You had matter and antimatter, and they made clumps and 0:05:36.720 --> 0:05:40.640 they kept expanding, and that's just how it occurred. At 0:05:40.720 --> 0:05:45.600 least that's the model that I've heard. There were at 0:05:45.680 --> 0:05:48.719 some point areas where there was a slight greater density, 0:05:49.200 --> 0:05:52.120 and you know, in the matter in the universevity works, 0:05:52.120 --> 0:05:55.320 a greater density will kind of collapse in the greater 0:05:55.320 --> 0:05:57.040 and greater and greater density to you have a galaxy, 0:05:57.040 --> 0:06:01.400 your plans or whatever the ions. Okay, all right, so 0:06:01.480 --> 0:06:03.760 that's pretty interesting. I feel like you should maybe stop 0:06:03.800 --> 0:06:07.120 advertising that they're U s Irvine students because I don't 0:06:07.120 --> 0:06:10.200 know if you're helping the marketing there. I think it's 0:06:10.240 --> 0:06:13.040 wonderful all these U see Irvine students are willing to 0:06:13.080 --> 0:06:16.359 stop and think about a random question from a randy, 0:06:16.760 --> 0:06:21.040 random scruffy looking dude and think about the universe. Likecent 0:06:21.120 --> 0:06:23.800 of people answer these questions. To me, they get full 0:06:23.800 --> 0:06:26.280 credit even just for trying, for thinking about it, for 0:06:26.440 --> 0:06:29.480 engaging right. To me, that's wonderful. When we first started 0:06:29.480 --> 0:06:31.200 this project, I was sure I was going to get 0:06:31.240 --> 0:06:34.000 one percent answers. So the fact that they don't know 0:06:34.320 --> 0:06:36.520 not a big deal. The fact that they try to answer, 0:06:36.800 --> 0:06:38.520 that's wonderful. I think you should try it down the 0:06:38.520 --> 0:06:40.400 streets of New York next and see what kind of 0:06:40.400 --> 0:06:43.080 reaction you get get out of here. Yeah, well, as 0:06:43.080 --> 0:06:45.160 you were suggesting, maybe I should go up to cal 0:06:45.200 --> 0:06:48.400 Tech and see see if they get them more precise answers. 0:06:48.800 --> 0:06:51.919 But everyone seems to say gravity as the answer to 0:06:51.960 --> 0:06:54.960 the question. Yeah, everybody says gravity, And I think that 0:06:55.120 --> 0:06:59.600 comes from everybody's feeling correctly that gravity plays a big role, right. 0:06:59.640 --> 0:07:02.280 Gravity is the thing that made these structures. Gravity is 0:07:02.279 --> 0:07:06.200 which responsible for holding a start together. Gravity controls the 0:07:06.200 --> 0:07:09.159 shape of the galaxy. Gravity certainly plays a big role, 0:07:09.960 --> 0:07:13.240 but I guess the twist is that it's not the 0:07:13.280 --> 0:07:15.760 only thing you need to make stars. Right. Gravity only 0:07:15.760 --> 0:07:19.200 clumps links together if you if you already have small 0:07:19.240 --> 0:07:22.200 clumps to begin with, right, that's right, Gravity is not 0:07:22.280 --> 0:07:25.440 the complete answer. If you had a universe that was 0:07:25.600 --> 0:07:30.200 totally smooth, right, completely smooth, then gravity couldn't do anything 0:07:30.920 --> 0:07:33.520 because each particle in the universe would be pulled both 0:07:33.640 --> 0:07:36.480 left and right with equal force because it would be 0:07:36.560 --> 0:07:39.240 equal amounts of stuff on both sides of it, And 0:07:39.280 --> 0:07:42.119 so every object would be sort of like pinned down 0:07:42.160 --> 0:07:45.800 by gravity. But it couldn't form any structures, right, So 0:07:45.880 --> 0:07:49.840 gravity can't make lumps. It can only exaggerate lumps. Once 0:07:49.880 --> 0:07:52.520 you've gotten a little bit started, we paint that picture 0:07:52.560 --> 0:07:54.360 a little bit more for me. So let's imagine a 0:07:54.440 --> 0:07:59.120 perfectly smooth universe, meaning that all the particles in the 0:07:59.240 --> 0:08:02.360 universe are kind of at the same distance from each 0:08:02.360 --> 0:08:06.320 other as every other particle in the universe exactly. So imagine, 0:08:06.680 --> 0:08:08.720 you know, every particle is on a grid, right, and 0:08:09.120 --> 0:08:11.800 they have one particle every centimeter or something. Right, So 0:08:12.200 --> 0:08:15.680 take a perfectly exact grid. Everyone. Every particle is one 0:08:15.720 --> 0:08:18.960 centimeter apart from the next particle exactly. And if you're 0:08:18.960 --> 0:08:22.080 thinking this is strange and artificial, it's actually very simple, right, 0:08:22.080 --> 0:08:25.680 And it's very natural. The opposite idea that there's one 0:08:25.680 --> 0:08:28.640 place where there's particles are closer together, or they're denser 0:08:28.760 --> 0:08:32.280 and they're denser, or something that's strange, that's unusual, that 0:08:32.320 --> 0:08:34.920 would be like, well, why they're not here. So having 0:08:34.960 --> 0:08:38.360 a perfectly smooth, symmetric universe as a as a starting 0:08:38.400 --> 0:08:41.680 point actually makes the most sense. It's the most natural concept, 0:08:42.320 --> 0:08:46.080 like a perfect jelly or like a perfect crystal exactly, 0:08:46.320 --> 0:08:49.000 like a perfectly smooth chocolate pudding with new lumps in it. Right. 0:08:49.880 --> 0:08:53.000 So if and and if the universe is infinite, you're 0:08:53.000 --> 0:08:58.440 saying that cloud of perfectly ordered particles would not clump 0:08:58.480 --> 0:09:01.760 together exactly. So take one random particle, right, And it 0:09:01.760 --> 0:09:03.760 doesn't matter which one you choose, because we set this 0:09:03.840 --> 0:09:06.280 up so that all the particles are exactly the same. 0:09:06.600 --> 0:09:09.760 So pick one random particle. Now, that particle is going 0:09:09.800 --> 0:09:12.199 to get pulled on by all the other particles in 0:09:12.240 --> 0:09:14.559 the universe due to gravity and other forces. But let's 0:09:14.600 --> 0:09:17.959 just think about gravity right now. Now, Um, there's an 0:09:18.000 --> 0:09:20.240 infinite number of particles pulling it to the left, and 0:09:20.280 --> 0:09:22.600 an infinite number of particles pulling it to the right, 0:09:22.840 --> 0:09:25.280 and up and down to right exactly, and in any 0:09:25.400 --> 0:09:28.679 any way you slice it, you get the same answer. Right. Um, 0:09:28.760 --> 0:09:31.520 you divide the universe into two halves around this particle, 0:09:31.840 --> 0:09:33.560 and one half of the universe is pulling it one way, 0:09:33.600 --> 0:09:35.080 the other half is pulling it the other way. It 0:09:35.160 --> 0:09:39.400 exactly balances out. It cancels perfectly. Right. It's like if 0:09:39.440 --> 0:09:41.160 you have two kids and each one is pulling on 0:09:41.160 --> 0:09:44.440 one arm, You're not going anywhere. Right. Does that happen 0:09:44.480 --> 0:09:47.920 to you often? That's a random hypothetical I just invented. 0:09:47.960 --> 0:09:49.520 It's not that I have two kids who often have 0:09:49.640 --> 0:09:53.440 totally different ideas about what we should do or um, 0:09:53.480 --> 0:09:55.280 where they want to go or where they want to eat. 0:09:55.880 --> 0:09:59.360 That's right, um. And so in this scenario, every particle 0:09:59.600 --> 0:10:03.760 is an equilibrium. Right. There's no way to begin lumpiness 0:10:03.760 --> 0:10:07.240 because everything is being tugged equally left and right or 0:10:07.400 --> 0:10:10.160 up and down, or you know, back and forth. So 0:10:10.200 --> 0:10:13.320 you would the universe would just sit there, It would 0:10:13.320 --> 0:10:16.760 just stay static. It would it wouldn't wouldn't move right, like, 0:10:17.200 --> 0:10:19.520 we would just stay there forever, because every particle would 0:10:19.520 --> 0:10:22.640 just be perfectly bounds where it is. Exactly. It's like 0:10:22.679 --> 0:10:25.240 if you put a ball in the bottom of a bowl, right, 0:10:25.240 --> 0:10:28.120 it's just gonna sit there. It's not gonna go anywhere, right, 0:10:28.160 --> 0:10:30.600 And that's exactly the situation of each of those particles. 0:10:30.600 --> 0:10:33.240 They're sitting in the bottom of a bowl. That bowl 0:10:33.320 --> 0:10:35.920 is the gravitational well made by all the other particles 0:10:35.920 --> 0:10:38.960 in the universe. And so if the universe is infinite, 0:10:39.080 --> 0:10:42.400 then you can apply the same argument to every particle, right. 0:10:42.480 --> 0:10:45.679 And so if you start out with an infinite, smooth universe, 0:10:46.240 --> 0:10:50.000 then you can't get any structure. You can't start to 0:10:50.000 --> 0:10:52.640 build anything. Hold on, you said that if that's only 0:10:52.679 --> 0:10:54.920 if the universe is infinite, But what happens if we 0:10:54.960 --> 0:10:58.319 have this perfect jelly and the universe is finite, meaning 0:10:58.880 --> 0:11:01.960 that at some point ends. Yeah, well, then this argument 0:11:01.960 --> 0:11:05.679 doesn't apply because there's some point um Because then this 0:11:05.800 --> 0:11:08.800 argument only applies to the very center of the universe. Right. Then, 0:11:08.840 --> 0:11:11.760 if the universe is finite, that means that it has 0:11:11.800 --> 0:11:14.400 a center, right, that there's someplace where there's an equal 0:11:14.440 --> 0:11:16.040 amount of stuff to the left and to the right 0:11:16.080 --> 0:11:19.079 and up and down right, and this argument would only 0:11:19.080 --> 0:11:21.680 apply right there, or if you go to the edge 0:11:21.720 --> 0:11:24.280 of all that stuff right. This is again assuming the 0:11:24.360 --> 0:11:26.160 universe is finite. If you go to the edge of 0:11:26.160 --> 0:11:28.560 all that stuff, the argument doesn't hold anymore. You have 0:11:28.640 --> 0:11:31.240 more stuff on one side than on the other. So 0:11:31.280 --> 0:11:34.280 in the scenario of a finite universe, everything would be 0:11:34.320 --> 0:11:37.319 attracted towards the center. Everything would be attracted towards the center. 0:11:37.600 --> 0:11:40.440 All everyone, all the particles would just go towards the center. 0:11:40.960 --> 0:11:42.720 And then what would happen? Man, I think it would 0:11:42.760 --> 0:11:45.559 get like a huge star or a massive black hole, 0:11:45.679 --> 0:11:47.920 or it would be a pretty crazy party, So the 0:11:48.000 --> 0:11:51.680 universe would be just one star or one black hole. 0:11:51.840 --> 0:11:55.160 I'm because I would be pretty complicated, but I think, yeah, 0:11:55.160 --> 0:11:58.400 you would end up with one really big blob of matter, um, 0:11:58.400 --> 0:12:00.200 and it would be you know, it wouldn't be compally 0:12:00.240 --> 0:12:03.920 compressed into a point because matter resists being compressed and 0:12:03.920 --> 0:12:06.319 and if it was spinning right then that keeps it 0:12:06.360 --> 0:12:09.920 from being compressed further. Um. I don't know if anybody's 0:12:09.960 --> 0:12:11.719 really studied what would happen if you just like had 0:12:11.720 --> 0:12:15.319 a huge universized blob of finite matter and then let 0:12:15.360 --> 0:12:18.800 it collapse. That would be fascinating. So it would be 0:12:19.040 --> 0:12:22.240 kind of this one just one, not two, not three, 0:12:22.320 --> 0:12:25.400 just one giant lump of stuff. That's right. And even 0:12:25.400 --> 0:12:29.400 in that scenario where the universe is perfectly smooth but finite, right, 0:12:29.840 --> 0:12:33.400 you can't get any asymmetries. Everything has to be perfectly 0:12:33.400 --> 0:12:35.920 balanced in every direction. Right. Yes, you have a center, 0:12:35.960 --> 0:12:38.480 so everything's attracted towards the center, but you can't like 0:12:39.000 --> 0:12:42.000 make stars clumping along the way as they're getting dragged 0:12:42.000 --> 0:12:44.640 towards the center. Still has to be perfectly smooth because 0:12:44.640 --> 0:12:47.240 it's the same in every direction, right, In order to 0:12:47.280 --> 0:12:49.120 get the kind of structure that we see when we 0:12:49.120 --> 0:12:50.720 look at the night sky, you have like a star 0:12:50.800 --> 0:12:53.079 here and no star there, and or galaxy here and 0:12:53.440 --> 0:12:57.079 galaxy there. That's and those are asymmetry. So right, that's 0:12:57.080 --> 0:13:00.480 a structure, that's a lump. Yeah, it's a in the 0:13:00.559 --> 0:13:03.720 universe exactly. So that's obviously not the universe we're in. 0:13:03.800 --> 0:13:06.719 We're not in a perfectly smooth, jelly universe, and we're 0:13:06.760 --> 0:13:12.080 not living in one giant, singular super cluster of stuff. 0:13:12.720 --> 0:13:15.560 We live in this kind of a stranger universe, right, 0:13:15.640 --> 0:13:17.320 and thank god we do, right. I mean, it would 0:13:17.360 --> 0:13:20.000 be pretty boring to live in an infinitely smooth pudding 0:13:20.559 --> 0:13:22.960 or even just have like one big star living in 0:13:22.960 --> 0:13:26.720 a perfect jelly. Seems pretty pretty peaceful to me. Again, 0:13:26.760 --> 0:13:28.440 I think you should have a snack before we do 0:13:28.520 --> 0:13:31.240 this podcast. Okay, although, as you tell you tend towards 0:13:31.240 --> 0:13:33.240 these food analogies that I think it just reflects what 0:13:33.360 --> 0:13:37.439 you're feeling rather than what you're thinking. Well, let's let's 0:13:37.720 --> 0:13:39.800 get into how lumpy the universe is and how it 0:13:39.880 --> 0:13:42.360 got that way. But first let's take a quick break. 0:13:54.880 --> 0:13:57.400 All right, So we don't live in a perfectly smooth universe, 0:13:57.440 --> 0:13:59.280 and we don't live in a universe such as one 0:13:59.480 --> 0:14:04.280 giant cluster, black hole, slash star. That's not the universe 0:14:04.280 --> 0:14:06.319 we'll live in, right, We are actually in a very 0:14:06.400 --> 0:14:09.520 lumpy universe. Yeah, And the universe, the structure universe is 0:14:09.520 --> 0:14:12.280 really fascinating. We should dig into it really deeply in 0:14:12.320 --> 0:14:14.560 another podcast episode and talk about it and why it 0:14:14.640 --> 0:14:16.520 is this way in that way. Um, but let's just 0:14:16.559 --> 0:14:19.360 review briefly sort of where we are in the universe, 0:14:20.000 --> 0:14:23.840 the the status of the lumps, the level of lumpiness 0:14:23.840 --> 0:14:26.080 of the universe. Yeah, so we we are sitting here 0:14:26.120 --> 0:14:29.000 on Earth presumably, that's right. We are two lumps on 0:14:29.040 --> 0:14:32.320 a rock. Yeah. Um, presumably most of our listeners are 0:14:32.560 --> 0:14:34.240 on Earth. And if you're not, by the way, if 0:14:34.240 --> 0:14:36.040 you're listening to this podcast and you're not on Earth, 0:14:36.160 --> 0:14:40.480 we really want to hear from you. Yeah. Absolutely, But 0:14:40.600 --> 0:14:43.160 we are in a big rock around rock, going around 0:14:43.280 --> 0:14:47.320 a sun, a star, and that's our solar system, right, 0:14:47.440 --> 0:14:49.880 and even that is super lumpy. I mean from the 0:14:49.880 --> 0:14:52.680 point of view of like how smooth this stuff distributed. 0:14:53.080 --> 0:14:55.200 You know, people are probably familiar with how far away 0:14:55.240 --> 0:14:57.880 the Sun is. It's you know, it takes a time 0:14:57.920 --> 0:15:00.000 for light to even get there. It's minutes and minute, 0:15:00.000 --> 0:15:02.000 it's in minutes, right, And the Sun itself is a 0:15:02.120 --> 0:15:05.560 huge blov of matter, but it's super far away. You know. 0:15:05.640 --> 0:15:08.200 The size of the Earth is enormous and the size 0:15:08.240 --> 0:15:09.800 of the Sun is enormous, but the size of the 0:15:09.840 --> 0:15:14.040 distance between them dwarfs both of them. Right, So even 0:15:14.080 --> 0:15:16.600 just the solar system is really really lumpy in that 0:15:16.640 --> 0:15:19.280 sense that the matter is concentrated and not spread out. 0:15:19.720 --> 0:15:22.640 And then our solarcism is inside of a galaxy. Right, 0:15:23.640 --> 0:15:26.240 and that's even lumpier from that point of view, right, 0:15:26.280 --> 0:15:29.960 Like the distance between stars is huge compared to the 0:15:29.960 --> 0:15:32.720 size of the stars. And it had some sort of structure, right, 0:15:32.720 --> 0:15:36.720 Like the galaxy has spirals and it's kind of thicker 0:15:36.760 --> 0:15:39.280 and more dense in the middle. Right, there's no structure 0:15:39.640 --> 0:15:42.120 at that scale too. Yeah, the galaxy told me it 0:15:42.160 --> 0:15:44.520 doesn't like when you talk about it's thickening waistline rhead. 0:15:45.000 --> 0:15:51.560 But it's true. It sparkly. I'm talking about its sparkliness. 0:15:51.880 --> 0:15:55.040 It's beautiful. It's beautiful, the milky way. Um, yeah, exactly. 0:15:55.040 --> 0:15:56.920 We got all these stars, hundred billions of stars, but 0:15:56.960 --> 0:15:59.080 they're not just a blob, right, They're not just distributed 0:15:59.160 --> 0:16:01.520 evenly all THEO. For a long time people thought that's 0:16:01.280 --> 0:16:03.920 what happened, But now we know that they're arranged in 0:16:03.920 --> 0:16:07.720 this amazing swirl pattern right or the center of the galaxy. 0:16:07.760 --> 0:16:09.400 And then we have these arms that come out and 0:16:09.440 --> 0:16:12.760 because it's rotating, those arms sort of dragged behind it, 0:16:13.320 --> 0:16:15.560 and uh, and you get this amazing swirl and then 0:16:15.560 --> 0:16:17.960 you can keep going like the galaxy is part of 0:16:17.960 --> 0:16:21.480 a supercluster of galaxies and that's super. No, you missed one? 0:16:21.680 --> 0:16:23.720 What you missed one? The galaxy is part of a 0:16:23.760 --> 0:16:26.880 cluster of galaxies, right, And when we talk about a cluster, 0:16:27.000 --> 0:16:29.920 we mean things that are gravitationally bound to each other, 0:16:29.960 --> 0:16:32.960 that essentially are orbiting each other over billions and billions 0:16:33.000 --> 0:16:36.320 of years. So we and ours is called the local group, 0:16:36.440 --> 0:16:40.000 right Like our cluster of galaxies is very imaginatively called 0:16:40.040 --> 0:16:43.400 the local group. I know that sounds like a temporary 0:16:43.480 --> 0:16:45.240 name somebody came up with, like, oh, I need to 0:16:45.280 --> 0:16:47.400 call this something and talk to my advisor, and then 0:16:47.400 --> 0:16:49.120 it just stuck and they're like, dang, and I should 0:16:49.160 --> 0:16:52.960 have named it after my dog. What's the opposite of local? 0:16:53.200 --> 0:16:57.520 Like basically, just here, it means the galaxies near us, right, 0:16:58.040 --> 0:17:02.520 It's pretty lame name. Um yeah, so that's the cluster. 0:17:03.000 --> 0:17:05.760 You know, our galaxy cluster is green and you know 0:17:06.520 --> 0:17:12.480 local sources locally, that's right. I don't think it's vegan, 0:17:12.800 --> 0:17:22.160 but at least it's local, right. Um yeah, exactly. Our 0:17:22.200 --> 0:17:24.879 galaxy is part of a structure of of other with 0:17:25.040 --> 0:17:29.920 other galaxies. Even that cluster is part of another structure 0:17:29.960 --> 0:17:33.000 in the universe, right. Yeah. They call those superclusters, and 0:17:33.040 --> 0:17:37.560 these are basically clusters of clusters another imaginative name. Huh. 0:17:37.680 --> 0:17:39.920 And again you might ask, like, are these totally arbitrary? 0:17:39.920 --> 0:17:42.080 Is just making this up? Could you have organized it differently? 0:17:42.280 --> 0:17:44.640 The answers, No, there's some science behind it. We think 0:17:44.680 --> 0:17:48.159 about how these groups operate, you know, And essentially a 0:17:48.240 --> 0:17:52.000 supercluster is not just a really really big cluster, it's 0:17:52.080 --> 0:17:56.000 a cluster of clusters, meaning that the each cluster inside 0:17:56.000 --> 0:17:59.720 a supercluster is gravitationally bound to itself, and then those 0:17:59.760 --> 0:18:02.880 things themselves are gravitationally bound to each other, and that's 0:18:02.880 --> 0:18:05.199 what makes the super clustered. They're sort of trapped in 0:18:05.240 --> 0:18:08.520 a sort of gravitational bubble almost. Yeah, the way like 0:18:08.760 --> 0:18:11.280 you know, the Earth and the Moon are a gravitational system, right, 0:18:11.280 --> 0:18:13.880 which is embedded inside the Solar System, which is embedded 0:18:13.880 --> 0:18:17.000 inside the galaxy. Right, you might say it's arbitrary to 0:18:17.040 --> 0:18:18.760 define whether or not the Moon is part of the 0:18:18.760 --> 0:18:20.760 Earth system, of the Solar System, whatever. Really makes much 0:18:20.760 --> 0:18:22.919 more sense to consider the Earth to be part of 0:18:22.960 --> 0:18:25.239 our system, and then the Solar System may be part 0:18:25.280 --> 0:18:27.280 of the galaxy, rather than just say like, oh, it's 0:18:27.280 --> 0:18:30.439 all one big galaxy. So that's why we get these hierarchies, 0:18:30.640 --> 0:18:32.639 and it's amazing that we have these hierarchies, you know, 0:18:32.680 --> 0:18:34.840 and like also because you can zoom down right and 0:18:34.840 --> 0:18:36.719 you get like down to the atom and things are 0:18:36.800 --> 0:18:39.840 orbiting and stuff. So we have this over incredible the 0:18:40.000 --> 0:18:45.400 different distances from microscopic to what megascopic we have similar 0:18:45.400 --> 0:18:47.800 structures of things orbiting each other and right on these 0:18:47.840 --> 0:18:51.080 on these large scales, like an infinite Russian doll, you 0:18:51.119 --> 0:18:54.280 can stack them up almost infinitely, seems yeah, but infinite, 0:18:54.280 --> 0:18:56.120 we don't know, right, We talked about that another time, 0:18:56.160 --> 0:18:59.800 Like we think the universe probably has the smallest scale, 0:19:00.119 --> 0:19:02.480 and when we talk about the structure of the galaxy 0:19:02.560 --> 0:19:04.720 as the structure of the the universe, and another podcast episode 0:19:04.720 --> 0:19:07.240 we'll talk about the biggest structures in the university is 0:19:07.280 --> 0:19:09.720 a whole other fascinating topic. You can keep going in. 0:19:09.720 --> 0:19:12.080 There are bigger, bigger structures, right. Well, there's a point 0:19:12.080 --> 0:19:15.560 where they stop. Yeah, at some point they stop. At 0:19:15.600 --> 0:19:19.119 some point they stop. There's an end to the Russian doll, 0:19:19.280 --> 0:19:21.600 as far as we know, there is. There's the largest 0:19:21.640 --> 0:19:23.960 Russian doll. Yeah. Um, anyway, but that's the topic for 0:19:24.000 --> 0:19:28.200 another another day. Let's talk about why why we have structure. Yeah, 0:19:28.200 --> 0:19:30.080 the point is that there is structure, right, Like, we're 0:19:30.119 --> 0:19:32.880 not in a smooth universe and we're not just one 0:19:32.920 --> 0:19:36.520 giant lump. There is like texture to the universe, right, 0:19:36.520 --> 0:19:40.399 there's features, there's things to look at, there's good stuff 0:19:40.440 --> 0:19:44.960 to see exactly, and as our you see I question 0:19:45.040 --> 0:19:49.240 answers earlier said gravity is responsible for forming those things. 0:19:49.240 --> 0:19:52.000 But gravity couldn't start those structures, right, That was the 0:19:52.000 --> 0:19:54.480 point we were making earlier. So the point is that 0:19:54.520 --> 0:19:57.960 gravity can't make lumps. When you start a lump, gravity 0:19:57.960 --> 0:20:00.399 will accelerate like a chain reaction. Right, when you have 0:20:00.520 --> 0:20:03.119 one point that's denser than everything else, it will have 0:20:03.160 --> 0:20:06.320 a stronger gravitational pull and it'll start to attract stuff 0:20:06.359 --> 0:20:09.080 and then look at heavier and have a stronger gravitational pull, 0:20:09.359 --> 0:20:11.919 and it will feed on itself. But if everything is smooth, 0:20:12.000 --> 0:20:14.400 then you can't. So the question is, so gravity can 0:20:14.400 --> 0:20:17.600 make lumps bigger, but the question really comes down to 0:20:17.880 --> 0:20:20.119 where did the first lumps come from. It's kind of 0:20:20.160 --> 0:20:23.760 like gravity can roll a snowball down the hill, but 0:20:23.840 --> 0:20:28.320 it can't sort of start the snowball rolling, Yeah, exactly, exactly, 0:20:28.359 --> 0:20:30.360 Like once it's rolling, it gets bigger and lump here. 0:20:30.400 --> 0:20:33.560 But you need some sort of something to get that 0:20:33.640 --> 0:20:35.760 snowball going. Yeah, you have to knock it out of 0:20:35.800 --> 0:20:41.920 equilibrium to get it to get things snowballing exactly. Okay, 0:20:44.480 --> 0:20:47.000 all right, So how did the universe key head lumps? 0:20:47.320 --> 0:20:50.560 How is it not perfectly smooth or one giant? So 0:20:50.600 --> 0:20:52.479 that was a big mystery for a long time, right, 0:20:52.520 --> 0:20:55.840 because it's very natural to think that the universe started symmetrically. 0:20:56.160 --> 0:20:58.119 I think probably the most popular model for how the 0:20:58.160 --> 0:21:01.680 universe started is the universe versus infinite and that has 0:21:01.760 --> 0:21:03.920 infinite amount of matter in it, and that was created 0:21:03.920 --> 0:21:07.240 in the first moments, right that we don't understand at all. 0:21:07.680 --> 0:21:09.800 But not understanding it means we want to start with 0:21:09.840 --> 0:21:12.600 the simplest idea. Okay, And it's not very simple to 0:21:12.640 --> 0:21:14.760 imagine the creation of an infinite universe with an infinite 0:21:14.760 --> 0:21:16.720 amount of stuff in it. But if you're gonna go there, 0:21:17.200 --> 0:21:19.359 it makes more sense to say that the universe starts 0:21:19.359 --> 0:21:22.360 out smooth. That's where this idea of smoothness comes right, right, 0:21:22.400 --> 0:21:26.080 like simplicity, because the opposite like, oh, that the universe 0:21:26.160 --> 0:21:28.679 was created with some initial lumpiness, that's weird. Because then 0:21:28.720 --> 0:21:31.320