WEBVTT - What is the Big Rip? 0:00:08.520 --> 0:00:14.000 Hey, okay, I'm confused about something in the Star Wars universe. Well, 0:00:14.040 --> 0:00:16.960 I've seen those movies, which means I have a PhD 0:00:17.000 --> 0:00:19.200 in them. That's how they give out PhDs, right yeah, 0:00:19.200 --> 0:00:21.799 at Star Wars University. I think that's the only requirement 0:00:22.040 --> 0:00:26.400 sw go wookies. So my confusion is the Star Wars 0:00:26.520 --> 0:00:29.840 universe has humans in it, right, like people. Ah, well 0:00:29.840 --> 0:00:32.080 that's never clear. You know, they look like humans, but 0:00:32.159 --> 0:00:37.519 technically they're all aliens right there e t s extrat rest. Well, 0:00:37.520 --> 0:00:41.519 they're definitely biological humans. But they also have like super 0:00:41.560 --> 0:00:45.559 advanced technology, right like far future stuff. Yeah. Yeah, they 0:00:45.560 --> 0:00:48.720 have war drives and spaceships and light sabers. But it 0:00:48.840 --> 0:00:52.040 also says that it takes place a long, long time ago, 0:00:52.880 --> 0:00:55.160 So like, is it the past or is it the 0:00:55.280 --> 0:00:59.080 future with fancy technology? Yeah? Yeah, I know. That's the 0:00:59.080 --> 0:01:01.920 beauty of Georgia. Lucas is opening line a long time 0:01:01.960 --> 0:01:04.240 ago in a galaxy far far away. This is something 0:01:04.280 --> 0:01:06.559 that happened a long time ago, that's happening right now, 0:01:07.160 --> 0:01:09.600 or it's going to happen in the future. Maybe in 0:01:09.600 --> 0:01:12.200 the future I'll finally understand it. You just need to 0:01:12.200 --> 0:01:14.440 rewatch the movies a few times. Maybe it's time I 0:01:14.480 --> 0:01:32.240 get a second PhD hi am or handmade cartoonists and 0:01:32.319 --> 0:01:35.399 the co author frequently asked questions about the Universe. Hi, 0:01:35.480 --> 0:01:38.320 I'm Daniel. I'm a particle physicist and a professor at 0:01:38.360 --> 0:01:41.640 UC Irvine, and I'm not prepared to defend the physics 0:01:41.720 --> 0:01:44.840 of Star Wars. There is physics in Star Wars. That's 0:01:44.840 --> 0:01:47.480 the problem. There isn't that much, so we can't defend 0:01:47.520 --> 0:01:50.360 it well. I think from the beginning they say it's 0:01:50.360 --> 0:01:53.440 a fantasy. They never claim it's science. I think that's 0:01:53.440 --> 0:01:56.240 how George Lucas conceived it. He always thought of it 0:01:56.320 --> 0:01:59.680 as a fantasy. It's like fantasy plus Westerns in space. 0:02:00.160 --> 0:02:02.600 Anything is better in space, right except breathing? I guess 0:02:02.920 --> 0:02:05.560 I don't know. It's dessert better in space necessarily. If 0:02:05.560 --> 0:02:08.480 it's ice cream, sure that's gonna stay less and cold, 0:02:08.560 --> 0:02:11.400 isn't it. I've had astronaut ice cream. It doesn't compare. 0:02:11.760 --> 0:02:14.640 Welcome to our podcast, Daniel and Jorge Explain the Universe, 0:02:14.720 --> 0:02:17.079 a production of I Heart Radio, in which we think 0:02:17.120 --> 0:02:20.680 that the mysteries out in space are actually quite delicious. 0:02:20.760 --> 0:02:23.840 We take a deep sip of all of the questions 0:02:23.880 --> 0:02:26.440 we have about the nature of the universe, the way 0:02:26.480 --> 0:02:28.760 things work, the way things are, the way they come 0:02:28.760 --> 0:02:32.600 together to make this universe that we can somehow amazingly 0:02:32.800 --> 0:02:37.840 inexplicably analyze and understand with our tiny little brains. We 0:02:37.880 --> 0:02:41.399 can cast our simple mathematical stories over them and try 0:02:41.440 --> 0:02:44.639 to get some understanding for why things happen and how 0:02:44.680 --> 0:02:47.480 things happen. That's right, It's an amazing universe. And we 0:02:47.600 --> 0:02:50.840 like to use the Force here in this podcast to 0:02:50.960 --> 0:02:54.120 understand things like forces in the universe and particles and 0:02:54.560 --> 0:02:57.360 stars and galaxies and black holes, because one day we 0:02:57.440 --> 0:02:59.560 might be able to get really up close to these 0:02:59.639 --> 0:03:02.000 kinds of we use the force. Really, are you using 0:03:02.000 --> 0:03:04.399 the Jedi mind trick on me right now? I'm using 0:03:04.400 --> 0:03:08.200 the electromagnetic force that we're transmitting on That's true, we 0:03:08.240 --> 0:03:10.440 are using forces, But I thought there was a big 0:03:10.480 --> 0:03:12.959 difference between forces and the force. I mean, in the 0:03:13.000 --> 0:03:15.680 Star Wars universe, they have the normal forces, right, they 0:03:15.720 --> 0:03:19.520 also have the force. Mm. Well, we've always talked in 0:03:19.560 --> 0:03:22.160 this podcast how there might be one unifying force to 0:03:22.240 --> 0:03:26.560 the universe, right, so maybe there is the force. Do 0:03:26.720 --> 0:03:29.520 we also discuss miny Chlorians, where it's a far too 0:03:29.520 --> 0:03:32.919 controversial even for us. See that's an attempt to describe 0:03:32.919 --> 0:03:35.920 the force in terms of a scientific explanation. Maybe that's 0:03:35.920 --> 0:03:37.720 why it wasn't so popular that you mean the Star 0:03:37.720 --> 0:03:42.840 Wars movies weren't popular the prequels. Man, Yes, there's a 0:03:42.840 --> 0:03:46.160 lot of controversy there. Yeah, they only made three kajillion dollars. Yeah, 0:03:46.160 --> 0:03:48.400 but it is an awesome universe, full of galaxies that 0:03:48.640 --> 0:03:51.120 are far far away and lots of events that happened 0:03:51.160 --> 0:03:53.600 a long long time ago. Because the universe has been 0:03:53.640 --> 0:03:56.119 around for a pretty long time and hopefully it will 0:03:56.160 --> 0:03:59.960 be around for quite a while longer. Maybe, But because 0:04:00.040 --> 0:04:02.400 is that it is a physical universe. It is at 0:04:02.440 --> 0:04:05.720 the mercy of forces. We think that forces in this 0:04:05.880 --> 0:04:09.680 universe control the shape of everything we experience, from the 0:04:09.720 --> 0:04:11.640 reason that you don't fall through your chair to the 0:04:11.680 --> 0:04:13.840 reason you are held on the Earth and the Earth 0:04:13.920 --> 0:04:16.680 orbits around the Sun. The very structure of the galaxy 0:04:16.720 --> 0:04:19.920 and the large scale structure of the universe are determined 0:04:20.000 --> 0:04:22.400 by forces. Wait wait, wait, are you saying gravity is 0:04:22.400 --> 0:04:27.320 a force? Gravity is a fictitious force. Yes, absolutely, it's 0:04:27.360 --> 0:04:31.080 a Star Wars force. It's the Star Wars of forces. 0:04:31.360 --> 0:04:33.080 I always wonder how they can stand up in those 0:04:33.120 --> 0:04:35.440 spaceships when they're out in space fiction. That's how they 0:04:35.480 --> 0:04:38.039 can do it. But in our universe, forces do determine 0:04:38.040 --> 0:04:41.320 the large scale structure of everything if you include gravity 0:04:41.320 --> 0:04:43.320 on that list, and they control how the universe in 0:04:43.320 --> 0:04:46.600 the past has turned into universe we see today, and 0:04:46.640 --> 0:04:50.200 also they will determine the universe's future. That's right, because 0:04:50.400 --> 0:04:55.719 as still an ever lasting as the universe may seem, 0:04:55.760 --> 0:04:58.800 it's actually changing. It has been changing, and it will 0:04:58.880 --> 0:05:01.800 keep on changing. Used to be super super diverse, small 0:05:01.920 --> 0:05:04.679 or at least super super dense, and now it's much bigger, 0:05:04.839 --> 0:05:07.279 and it might keep changing in the future. Yeah, it 0:05:07.279 --> 0:05:09.599 can be difficult to sort of think on the time 0:05:09.640 --> 0:05:12.320 scale of the universe. You're used to looking up in 0:05:12.320 --> 0:05:14.479 the night sky and seeing it always be the same. 0:05:14.560 --> 0:05:17.440 The stars are not disappearing, they're not changing, they're not dancing. 0:05:17.520 --> 0:05:20.360 But we have learned in many situations that the universe, 0:05:20.440 --> 0:05:23.719 or even just the Earth changes on time scales that 0:05:23.760 --> 0:05:26.560 are well beyond what humans are used to thinking about. 0:05:26.720 --> 0:05:29.560 Millions of years ago, the Earth looked quite different. Billions 0:05:29.600 --> 0:05:32.840 of years ago, the Earth didn't even exist, and so 0:05:32.920 --> 0:05:36.080 the universe itself is rapidly changing, and we don't know 0:05:36.400 --> 0:05:38.840 if we are a significant fraction of the way through 0:05:38.880 --> 0:05:41.000 the history of the universe, or if this is just 0:05:41.160 --> 0:05:44.240 the first brief flash of a universe that will last 0:05:44.279 --> 0:05:48.359 for trillions or quadrillions or quintillions of years. Are you 0:05:48.400 --> 0:05:52.280 asking if the universe has peaked already? Exactly is it 0:05:52.360 --> 0:05:55.320 time to buy or sell shares in the universe? Well, 0:05:55.360 --> 0:05:57.760 I think by shares of the universe, you just won't 0:05:57.760 --> 0:06:01.560 be alive, probably by time someone catches in the universe. 0:06:01.720 --> 0:06:04.520 Who exactly can you sell your shares the universe too? 0:06:04.560 --> 0:06:06.320 I suppose is there a market out there in the 0:06:06.400 --> 0:06:09.920 multiverse stock market? Maybe you just enjoy the dividends. Life 0:06:09.920 --> 0:06:12.200 is pretty good, right, life is pretty good. In fact, 0:06:12.279 --> 0:06:15.200 I enjoy the universe. But I wonder how long this 0:06:15.240 --> 0:06:18.000 situation will last. How long will we be able to 0:06:18.080 --> 0:06:20.680 sit on a nice cozy rock toasting our toes by 0:06:20.680 --> 0:06:23.080 the fire of a distant sun. Is this something which 0:06:23.080 --> 0:06:26.120 will last for billions or trillions of years in our universe? 0:06:26.520 --> 0:06:28.920 Or is it a brief moment of respite on this 0:06:28.960 --> 0:06:31.880 resort we call Earth. Yeah, because the universe has been 0:06:31.960 --> 0:06:35.120 changing and it will keep on changing, probably, and so 0:06:35.200 --> 0:06:37.919 we can ask what does the future hold? Can we 0:06:37.960 --> 0:06:40.440 predict what's going to happen to the universe and we 0:06:40.560 --> 0:06:42.920 measure it, and how do we know that's what it's 0:06:42.920 --> 0:06:45.360 gonna do? Are we better able to predict the future 0:06:45.400 --> 0:06:47.520 of the universe than we are able to predict the 0:06:47.520 --> 0:06:50.159 future of the stock market, for example? And so to 0:06:50.200 --> 0:06:57.159 be on the podcast, we'll be asking the question what 0:06:57.440 --> 0:07:01.960 is the Big Rip? As this related to anyone's pants, Daniel, 0:07:02.120 --> 0:07:04.160 It's what happens if you eat too much astronaut ice 0:07:04.160 --> 0:07:06.200 cream or you sit down to watch the Star Wars 0:07:06.240 --> 0:07:09.720 movies one too many times. No, it's a fun speculative 0:07:09.760 --> 0:07:13.720 idea about the potential future of the universe because we're 0:07:13.720 --> 0:07:16.600 still developing our understanding of how the universe works and 0:07:16.640 --> 0:07:19.120 what all the forces at play are, and there are 0:07:19.320 --> 0:07:23.160 enormous gaps remaining in that understanding. There's a large set 0:07:23.200 --> 0:07:26.640 of possible futures for the universe, and the Big Rip 0:07:26.760 --> 0:07:29.600 is one of the craziest ones. Yeah. I think we've 0:07:29.640 --> 0:07:31.800 talked a little bit in this podcast about the end 0:07:31.800 --> 0:07:34.640 of the universe, right. We had Katie Mack here talked 0:07:34.640 --> 0:07:37.080 about her book The end of everything, and she kind 0:07:37.080 --> 0:07:39.280 of walked us through a couple of the possible scenarios 0:07:39.280 --> 0:07:41.040 for the universe. Yeah, that was a lot of fun 0:07:41.080 --> 0:07:42.880 and it's a great book folks should check out if 0:07:42.880 --> 0:07:46.280 you're interested in cosmology and reading about depressing ways we 0:07:46.320 --> 0:07:48.560 can all die. And we also talked in great depth 0:07:48.600 --> 0:07:51.120 on the podcast about some of the forces that are 0:07:51.160 --> 0:07:53.520 at play there and what we understand about them and 0:07:53.560 --> 0:07:56.840 what we don't understand about how they are still shaping 0:07:56.880 --> 0:07:59.920 our universe today. Now this is called the Big Rip. 0:08:00.080 --> 0:08:03.000 Now our physicist gonna change the name a little bit 0:08:03.080 --> 0:08:06.920 later on though, the bigger rip or the even larger, 0:08:07.160 --> 0:08:09.520 the even bigger rip. I'm looking forward to the super 0:08:09.600 --> 0:08:12.640 rip because then the rs blend together. The cosmic rip 0:08:12.680 --> 0:08:14.800 would in the cosmic rip be a better name for it, yeah, 0:08:14.880 --> 0:08:16.880 or the cosmic rift. But we do have a lot 0:08:16.880 --> 0:08:20.080 of ideas about how the universe might evolve and what 0:08:20.200 --> 0:08:22.320 might happen to it trillions of years into the future 0:08:22.400 --> 0:08:24.600 or maybe billions of years into the future, and this 0:08:24.680 --> 0:08:26.720 is one of those ideas, and it's pretty interesting. It's 0:08:26.720 --> 0:08:29.200 one of maybe what like three or four possible things 0:08:29.200 --> 0:08:31.000 that might happen to the universe. I think it's actually 0:08:31.000 --> 0:08:33.840 an infinite spectrum of possible outcomes to the universe. So yeah, 0:08:33.840 --> 0:08:36.000 this is one of those, right right, that's right. They 0:08:36.000 --> 0:08:38.480 could be a big rip, a bigger rip, small rip, 0:08:38.640 --> 0:08:41.200 a medium sized rip, a pocket size rip, and then 0:08:41.240 --> 0:08:43.720 of course there's all the ideas we just can't anticipate 0:08:43.800 --> 0:08:47.040 because we are just so clueless about how the universe works. 0:08:47.080 --> 0:08:50.680 We've only understood recently pretty basic stuff about things that 0:08:50.679 --> 0:08:53.439 are controlling the evolution of the universe, so we should 0:08:53.440 --> 0:08:57.120 definitely avoid being too confident but even categorizing the amount 0:08:57.200 --> 0:08:59.360 of our understanding. All right, So today we're going to 0:08:59.400 --> 0:09:02.040 focus on one possible thing that might happen to the universe. 0:09:02.240 --> 0:09:04.160 And so, as usual, we were wondering how many people 0:09:04.200 --> 0:09:06.600 have thought about the big Rip or what it could be. 0:09:06.720 --> 0:09:09.600 So thanks very much to everybody who answers these questions 0:09:09.600 --> 0:09:11.640 for the podcast, and if you would like to parts 0:09:11.679 --> 0:09:14.800 to pay for future episodes, please don't be shy. It's easy, 0:09:15.000 --> 0:09:17.760 it's fun, it doesn't hurt at all, Just right to me. 0:09:17.880 --> 0:09:20.920 Two questions at Daniel and Jorge dot com. So think 0:09:20.960 --> 0:09:22.760 about it for a second. What do you think the 0:09:22.800 --> 0:09:26.000 big rip is? Here's what people had to say. I 0:09:26.040 --> 0:09:27.880 think the big Rip is one of the possible ways 0:09:27.920 --> 0:09:31.400 the universe might end UM where something at the subatomic level, 0:09:31.760 --> 0:09:34.480 basically the whole universe on rabbles on itself. And I 0:09:34.520 --> 0:09:36.160 want to say it has something to do with anti matter. 0:09:36.240 --> 0:09:43.480 Maybe this was disgust UM two, like a meeting UM 0:09:43.679 --> 0:09:47.199 took place where a lot of known physicists We're talking 0:09:47.200 --> 0:09:54.839 about how the universe might end and theories, and reportedly 0:09:56.120 --> 0:10:01.680 UM at this meeting, bon Laborritos were or so I 0:10:01.800 --> 0:10:06.679 think somehow it's linked to this meeting. So the Big 0:10:06.760 --> 0:10:08.560 Rip is a scenario for the end of the universe 0:10:08.559 --> 0:10:13.600 where basically space time expands so quickly that every particle, 0:10:13.800 --> 0:10:17.240 every subparticle gets ripped apart from each other and basically 0:10:17.320 --> 0:10:20.360 can never meet another because the distance between any one 0:10:20.400 --> 0:10:22.319 and another it's expanding fast from the speed of light, 0:10:22.400 --> 0:10:25.079 so it's not very fun. The big rip is when 0:10:25.120 --> 0:10:28.240 the universe just rips itself apart because it doesn't have 0:10:28.360 --> 0:10:31.440 enough mass for the gravity to crunch back in on itself. 0:10:31.679 --> 0:10:35.280 The group is a theory that posits that at the 0:10:35.320 --> 0:10:37.760 auto is the end of the universe UM, there would 0:10:37.800 --> 0:10:42.439 be almost like an inflation that causes everything in the 0:10:42.520 --> 0:10:46.400 universe to move further apart, but um at a rapid 0:10:46.480 --> 0:10:50.280 rot almost like an explosion. I think, all right, some 0:10:50.360 --> 0:10:55.600 pretty definitive answers here. It's when everything ripped apart. Yeah, 0:10:55.600 --> 0:10:57.840 in that sense, you might say it's a well named 0:10:57.880 --> 0:11:00.719 physics theory. Yeah, yeah, I'll get it to them. Oh well, 0:11:00.800 --> 0:11:02.720 let's find out what it is first though, and see 0:11:02.720 --> 0:11:05.120 if it's related to a banana barrito and ripping into 0:11:05.160 --> 0:11:08.960 a banana bridle. I'm not sure where that comment was going. 0:11:09.120 --> 0:11:11.040 It was like a burrito made out of banana peals? 0:11:11.120 --> 0:11:12.920 Is that the reference? Yeah, I don't know. That's a 0:11:12.920 --> 0:11:17.439 slippery slope there. To mess with a burrito wrappings. I 0:11:17.480 --> 0:11:19.280 don't know if you're supposed to eat a banana barrito 0:11:19.440 --> 0:11:22.200 or smoke it. That's actually not a bad idea to 0:11:22.200 --> 0:11:24.760 put plantains inside of a burrito. I think you got 0:11:24.800 --> 0:11:28.040 something here. Listener, Well, let's get into a Daniel step 0:11:28.080 --> 0:11:30.120 us through what is the big rip? So the big 0:11:30.200 --> 0:11:33.640 rip is sort of like a super accelerated version of 0:11:33.640 --> 0:11:37.080 what we already think is happening to our universe. Current 0:11:37.240 --> 0:11:40.920 accepted idea of the cosmology of the universe. Is that 0:11:41.000 --> 0:11:45.120 the universe is expanding, and that that expansion is accelerating, 0:11:45.480 --> 0:11:48.480 meaning things are getting further and further apart. New spaces 0:11:48.559 --> 0:11:51.400 being created all the time, everywhere in the universe, and 0:11:51.440 --> 0:11:54.840 that's happening faster and faster every year. So even our 0:11:54.880 --> 0:11:58.600 current universe is sort of already tearing itself apart. An 0:11:58.640 --> 0:12:02.080 expansion is happening, and it's happening faster and faster every year. 0:12:02.240 --> 0:12:05.280 The Big Rip is like a super charged version of 0:12:05.320 --> 0:12:09.280 that that's going to accelerate the acceleration of that expansion, 0:12:09.640 --> 0:12:12.760 so that everything gets pulled apart to the tiniest bits 0:12:12.800 --> 0:12:15.160 at the end of time. Right, that's something we only 0:12:15.240 --> 0:12:17.920 learned about recently, right, maybe in the last hundred years, 0:12:17.920 --> 0:12:21.000 that the universe is actually expanding, it's not sitting still. Yeah, 0:12:21.120 --> 0:12:23.320 we learned about a hundred years ago that the universe 0:12:23.440 --> 0:12:26.360 is not just like a bunch of stars floating in space. 0:12:26.440 --> 0:12:28.920 Back before Edwin Hubble, in the beginning of the last century, 0:12:29.280 --> 0:12:32.240 people thought the universe was just like one galaxy. There's 0:12:32.240 --> 0:12:34.600 just a bunch of stars out there floating in space, 0:12:34.679 --> 0:12:37.120 and it was the way it was and always had been, 0:12:37.640 --> 0:12:39.680 and the most natural theory for the universe was that 0:12:39.720 --> 0:12:41.839 it always had been that way, and it always would 0:12:41.840 --> 0:12:43.520 be that way. It was just sort of like static 0:12:43.720 --> 0:12:47.800 and constant. But then Hubble saw other galaxies super duper 0:12:47.840 --> 0:12:51.040 far away. He identified smudges in the telescopes, not as 0:12:51.160 --> 0:12:55.160 nebula in our galaxy, but actual separate galaxies far away, 0:12:55.559 --> 0:12:57.720 and he was able to measure the velocity of those 0:12:57.720 --> 0:13:00.280 galaxies to see they were all moving away from us. 0:13:00.600 --> 0:13:04.520 So surprise, the prize the universe is actually expanding. Mm hmm, 0:13:04.679 --> 0:13:07.880 super interesting. How did he measure that the galaxy super 0:13:07.920 --> 0:13:10.240 moving away? You can measure the redshift of the light 0:13:10.400 --> 0:13:13.520 from those galaxies, so it looks a little redder than 0:13:13.720 --> 0:13:15.680 the life from our galaxy, Then you know it's moving 0:13:15.679 --> 0:13:17.439 away from me. If it looked a little bluer, it 0:13:17.480 --> 0:13:19.600 would mean that it was moving towards us. Things that 0:13:19.640 --> 0:13:22.679 emit light and have a relative velocity, the frequency of 0:13:22.720 --> 0:13:25.760 that light changes. It's a basic Doppler shift kind of effect, 0:13:26.040 --> 0:13:28.160 and things that are moving away from us, the light 0:13:28.200 --> 0:13:30.680 gets stretched out to make it redder. And Hubble was 0:13:30.760 --> 0:13:33.080 also able to measure the distance to these things, so 0:13:33.160 --> 0:13:34.920 he was able to show the things that are further 0:13:35.040 --> 0:13:37.920 away are moving away from us faster than things that 0:13:37.960 --> 0:13:40.880 are closer. Now that this makes sense with our sort 0:13:40.880 --> 0:13:44.320 of like theories about the universe and the makeup of 0:13:44.360 --> 0:13:47.160 it and what it could do, Like, what did Einstein 0:13:47.200 --> 0:13:49.360 think of this? Now, this was really confusing to folks 0:13:49.440 --> 0:13:52.880 like Einstein at the time. You know, before Einstein, we 0:13:52.920 --> 0:13:56.000 had an idea of gravity as a force. Mass pulls 0:13:56.040 --> 0:14:00.040 on other mass, stuffed tugs together gently. Right. Einstein in 0:14:00.160 --> 0:14:03.800 up with this idea that actually gravity is not a force, 0:14:03.840 --> 0:14:06.679 it's a curvature of the universe, that space itself is 0:14:06.720 --> 0:14:09.319 bent by mass and energy, and that's why things tend 0:14:09.440 --> 0:14:12.080 or sort of rolled together. The problem Einstein faced, even 0:14:12.120 --> 0:14:15.600 before Hubble's realization, was that this predicted that the universe 0:14:15.679 --> 0:14:17.880 would collapse, that all the mass and the energy and 0:14:17.880 --> 0:14:20.320 the universe would sort of pull itself together and shrink 0:14:20.360 --> 0:14:24.120 the universe. At the time, they thought the universe was static, right, 0:14:24.120 --> 0:14:25.800 They thought that it was just sort of hanging out there. 0:14:25.840 --> 0:14:30.240 So Einstein needed to invent something to balance the mass 0:14:30.240 --> 0:14:32.960 pulling everything together. So he added a fudge factor to 0:14:33.160 --> 0:14:37.000 his theory, something we now call the cosmological constant, which 0:14:37.000 --> 0:14:40.200 we've given outwards pressure to balance all of the mass 0:14:40.200 --> 0:14:42.920 coming in. So Einstein had this idea of a universe 0:14:42.960 --> 0:14:45.960 sort of balanced on a knife edge, this outward pressure 0:14:45.960 --> 0:14:49.120 providing exactly what you need to balance the inward pull 0:14:49.200 --> 0:14:52.080 of all the mass. And then Hubble literally blew that 0:14:52.160 --> 0:14:54.240 all up, right, because I guess if you imagine a 0:14:54.240 --> 0:14:56.720 bunch of stuff just floating out there in space as 0:14:56.720 --> 0:14:59.040 far as we knew back then, they should just all 0:14:59.040 --> 0:15:01.040 come together because of ay, right, Like, if you put 0:15:01.040 --> 0:15:03.160 two rocks out there in space, away from a lot 0:15:03.160 --> 0:15:05.440 of other stuff, is that there two rucks are going 0:15:05.480 --> 0:15:08.120 to attract each other and come together, right, And so 0:15:08.120 --> 0:15:10.000 if you have a bunch of stars or a bunch 0:15:10.040 --> 0:15:12.160 of planets out there in space, and the universe as 0:15:12.200 --> 0:15:14.720 we saw it, it should have all sort of crunched 0:15:14.800 --> 0:15:17.560 together by now, right. If things are just hanging out there, 0:15:17.600 --> 0:15:19.840 they have no relative velocity to start with. You put 0:15:19.840 --> 0:15:22.520 two rocks anywhere in the universe, they will tug on 0:15:22.560 --> 0:15:24.760 each other, and you give them enough time, they will 0:15:24.840 --> 0:15:27.480 come together. So Einstein was sort of like puzzled, like, 0:15:27.760 --> 0:15:30.360 why does my theory predict that the universe should collapse 0:15:30.560 --> 0:15:33.800 right into one giant black hole effectively? So he added 0:15:33.800 --> 0:15:36.240 a fudge factor, could in the universe be sort of 0:15:36.280 --> 0:15:39.600 like our Solar system, Like our Solar system is out 0:15:39.800 --> 0:15:42.080 out there in space, but it's not collapsing, right, Things 0:15:42.080 --> 0:15:44.480 are moving around in orbits. Yeah, there is something that's 0:15:44.560 --> 0:15:48.040 keeping the Solar system from collapsing rapidly, which is angular momentum. 0:15:48.160 --> 0:15:49.920 So the Earth, as you say, is in orbit around 0:15:49.920 --> 0:15:53.680 the Sun, just doesn't immediately collapse into the Sun. That orbit, though, 0:15:53.720 --> 0:15:56.840 will decay. You know, eventually the Earth will lose some 0:15:56.920 --> 0:15:59.640 of that velocity because it's bumping into stuff and it's 0:15:59.680 --> 0:16:03.080 really eating away energy and gravitational waves. So if you're 0:16:03.080 --> 0:16:06.760 talking about like the really deep future, then in Einstein's picture, 0:16:06.800 --> 0:16:10.560 eventually everything would collapse into a black hole. M But 0:16:10.960 --> 0:16:12.880 why did Einstein feel like you needed to add a 0:16:12.920 --> 0:16:15.520 fudge factor to make the universe static? Could in the 0:16:15.600 --> 0:16:17.800 universe be on its way to crunching down into a 0:16:17.800 --> 0:16:19.600 black hole? It could have been, and we didn't have 0:16:19.680 --> 0:16:22.320 great measurements, but the sort of prevailing view of the 0:16:22.400 --> 0:16:25.120 universe was that it was static. We didn't see anything moving, 0:16:25.160 --> 0:16:27.200 We didn't have great measurements. That which just sort of 0:16:27.200 --> 0:16:29.800 like the universe we thought we lived in. It looked static. 0:16:29.880 --> 0:16:32.160 It looks static, and so Hubble, you use this really 0:16:32.160 --> 0:16:36.600 cool observation by another astronomer, Henrietta Levitt, who discovered a 0:16:36.640 --> 0:16:39.440 certain kind of star called sephids. These are a particular 0:16:39.520 --> 0:16:41.160 kind of starring You can use a trick to tell 0:16:41.200 --> 0:16:43.280 how far away they are just by looking at the 0:16:43.360 --> 0:16:46.160 light from them. We have a whole episode about Ubble's discoveries. 0:16:46.360 --> 0:16:48.280 But Hubble was the first one to really be able 0:16:48.280 --> 0:16:50.400 to tell how far away things were, and so he 0:16:50.440 --> 0:16:53.080 could measure these velocities and he could tell that there 0:16:53.160 --> 0:16:55.400 was this trend that things further away we're moving away 0:16:55.400 --> 0:16:57.640 from us faster and faster. So that was the first 0:16:57.640 --> 0:17:01.520 clue that actually the universe is expanding. Yeah, that mustn't 0:17:01.520 --> 0:17:03.600 blown people's minds. How do you think that was received, 0:17:03.600 --> 0:17:05.960 that people believe Hubble at first, or were they like, no, 0:17:06.240 --> 0:17:08.640 you're crazy. I think the results were pretty solid because 0:17:08.680 --> 0:17:10.760 they were based on these sephids, which were pretty hard 0:17:10.760 --> 0:17:14.320 to dispute. And you can verify sephids using other distance 0:17:14.400 --> 0:17:17.439 metrics like parallax. For things that are close enough up, 0:17:17.720 --> 0:17:20.240 you can actually tell how far away something is based 0:17:20.240 --> 0:17:22.320 on how it wiggles in the sky as we go 0:17:22.440 --> 0:17:24.640 around the Sun. So there were a bunch of sefords 0:17:24.640 --> 0:17:28.479 that people could verify exactly how they work using other methods, 0:17:28.520 --> 0:17:30.560 and so it was kind of hard to dispute. But 0:17:30.680 --> 0:17:32.800 it did lead to a big puzzle. Right. People were like, 0:17:32.800 --> 0:17:34.840 hold on a second, we don't really understand what's going on. 0:17:35.000 --> 0:17:38.960 So then Einstein actually had bandoned the cosmological constant. He's like, well, 0:17:39.000 --> 0:17:41.560 scratch that. If the universe is expanding, we don't need 0:17:41.640 --> 0:17:44.840 the cosmological constant to resist the expansion. Things are just 0:17:44.880 --> 0:17:48.240 already zooming away from each other faster than gravity could 0:17:48.240 --> 0:17:51.760 otherwise pull them together. So the Einstein's fudge factor was 0:17:51.840 --> 0:17:54.920 actually holding back the universe in a way in his view, 0:17:55.119 --> 0:17:58.000 just by virtue of Einstein's equations, you're saying the universe 0:17:58.040 --> 0:18:01.160 would expand. What you're saying, No, you're saying the opposite. Right. 0:18:01.160 --> 0:18:04.000 Einstein's new view was like, all right, maybe mass is 0:18:04.080 --> 0:18:07.159 pulling the universe together, but it was already expanding. The 0:18:07.280 --> 0:18:09.360 sort of two different aspects to think about there. One 0:18:09.400 --> 0:18:11.120 is the rate of the expansion and the other sort 0:18:11.119 --> 0:18:15.040 of the acceleration. Mass tends to like slow down the 0:18:15.160 --> 0:18:18.679 rate of the expansion. But Einstein figured it's already expanding 0:18:18.680 --> 0:18:21.560 and expanding so fast that the mass doesn't have time 0:18:21.600 --> 0:18:24.199 to slow it down. It's sort of like hitting the 0:18:24.240 --> 0:18:26.960 brakes on a car that's already going super duper fast. 0:18:27.840 --> 0:18:31.280 So then he decided you didn't need that fudge factor. Yeah, 0:18:31.320 --> 0:18:34.480 he figured, look, the expansion is positive, maybe the acceleration 0:18:34.520 --> 0:18:36.919 is negative. Maybe mass is pulling everything forward, but we 0:18:36.960 --> 0:18:40.520 don't need the fudge factor the cosmological constant to explain 0:18:40.600 --> 0:18:43.560 why the universe is expanding anymore. Or he said, we 0:18:43.600 --> 0:18:45.639 don't need the fudge factor to explain why the universe 0:18:45.640 --> 0:18:48.719 hasn't crunched down. Yes, exactly, that's more accurate, thank you, 0:18:48.760 --> 0:18:52.199 because it's already like growing out of control, So you 0:18:52.200 --> 0:18:54.000 don't need to explain why it's not crunching that because 0:18:54.000 --> 0:18:57.200 it's on steroids the universe exactly. He invented the cosmological 0:18:57.280 --> 0:19:00.080 constant to explain why we had a static universe, and 0:19:00.119 --> 0:19:03.159 then we discovered, oh, the universe isn't static, it's expanding. 0:19:03.400 --> 0:19:05.000 So he sort of tossed it in the bin and 0:19:05.040 --> 0:19:07.840 apologized for it. Did it really well? Famously, he said 0:19:07.840 --> 0:19:10.880 that he thought it was one of his biggest scientific blunders. Yeah, 0:19:10.880 --> 0:19:14.320 that guy, I couldn't get anything right. I'd like to 0:19:14.320 --> 0:19:17.600 see humility in our great geniuses, you know. All right, well, 0:19:17.680 --> 0:19:20.399 let's talk about what could be causing this expansion and 0:19:20.400 --> 0:19:22.840 whether or not it's going to stay the same or 0:19:22.920 --> 0:19:26.520 maybe ripped the universe apart. But first, let's take a 0:19:26.600 --> 0:19:41.520 quick break. Alright, we're talking about the big rip, and 0:19:41.600 --> 0:19:44.520 so Daniel let it rip. So for a long time 0:19:44.520 --> 0:19:47.120 we knew that the universe was expanding, that we didn't 0:19:47.160 --> 0:19:49.919 really understand what had caused it to expand, and we 0:19:49.960 --> 0:19:52.080 thought maybe that mass in the universe was going to 0:19:52.160 --> 0:19:54.920 slow down that expansion, but we didn't understand like, is 0:19:54.960 --> 0:19:57.600 there enough mass in the universe to slow that expansion 0:19:57.640 --> 0:20:00.960 down eventually to zero and maybe bring it back to 0:20:01.000 --> 0:20:03.560 a big crunch, or is there not enough mass in 0:20:03.560 --> 0:20:06.000 the universe to slow down that expansion? Like a rock 0:20:06.160 --> 0:20:08.080 that you throw from the moon that will just go 0:20:08.160 --> 0:20:10.880 out forever, right, there's not enough mass on the moon 0:20:10.960 --> 0:20:13.199 to pull that rock back. Maybe the universe was like 0:20:13.240 --> 0:20:15.160 that and we just continue to drift further and further 0:20:15.200 --> 0:20:17.800 apart if there wasn't enough mass in the universe. So 0:20:17.840 --> 0:20:19.560 people wanted to know the answer to that question. They 0:20:19.560 --> 0:20:23.120