WEBVTT - What is making the Universe explode? 0:00:05.800 --> 0:00:09.440 Some of the most amazing moments in science were totally unexpected. 0:00:09.640 --> 0:00:13.680 You mean, like the discovery of microwave ovens or slinky 0:00:13.760 --> 0:00:16.200 So I heard it was also discovered by accident. Yeah, 0:00:16.280 --> 0:00:17.920 but I'm thinking about the times when you go out 0:00:17.960 --> 0:00:20.040 there just to double check something, something you thought you 0:00:20.079 --> 0:00:22.680 already understood, but you find an answer which makes no 0:00:22.760 --> 0:00:25.360 sense and forced you to change how you'd see things. Yeah. 0:00:25.400 --> 0:00:27.600 Like I heard one of the most fundamental things in 0:00:27.640 --> 0:00:31.240 the universe was actually discovered this way by accident, and 0:00:31.400 --> 0:00:33.879 it's totally amazing. It makes me wish that I had 0:00:33.920 --> 0:00:36.640 been involved, and it makes us see the universe differently, 0:00:36.720 --> 0:00:39.599 makes us see everything differently. Is it more impressive than 0:00:39.640 --> 0:00:42.960 as slinky in a microwave? That's pretty hard to top, 0:00:43.200 --> 0:00:58.600 but I think this one does. Hi, I'm RhE make cartoonists, 0:00:58.760 --> 0:01:01.560 and I'm Daniel. I'm a article physicists, and this is 0:01:01.600 --> 0:01:06.440 our podcast. Daniel and Jorgey explain the universe today on 0:01:06.480 --> 0:01:13.080 the program. What is dark energy and why is it 0:01:13.280 --> 0:01:18.000 everywhere in filling the universe? Is it powerful? Is it dangerous? 0:01:18.440 --> 0:01:20.880 Is it dark after all? Will it stain your clothes? 0:01:21.959 --> 0:01:25.919 And most important, why is it causing the universe to explode. 0:01:26.120 --> 0:01:28.840 The universe is exploding, people, but don't get out of 0:01:28.840 --> 0:01:31.559 your cars. It's going to take a while. Dark energy 0:01:31.600 --> 0:01:34.240 is a mysterious topic. We went around and we asked people, 0:01:34.319 --> 0:01:37.200 what do you know about dark energy? Um, is it 0:01:37.319 --> 0:01:39.760 like empty space? I'm not sure. No, I have no 0:01:39.840 --> 0:01:44.000 idea about it. It's like empty energy. Is dark energy 0:01:44.080 --> 0:01:47.200 something with black holes? I don't know, but that's my speculation. 0:01:48.400 --> 0:01:50.960 So most people really seem to have almost no idea 0:01:51.000 --> 0:01:54.040 what dark energy is, which as a physicist, really surprised 0:01:54.040 --> 0:01:56.360 me because it's one of the most dramatic and amazing 0:01:56.400 --> 0:01:59.840 discoveries of the last thirty years. Yeah, it's but people 0:02:00.000 --> 0:02:01.680 what it has seemed to have heard about it, right, 0:02:01.720 --> 0:02:04.600 It sounded really familiar, but they didn't know what it was. Yeah, 0:02:04.640 --> 0:02:06.920 some people thought it was dark matter. Some people maybe 0:02:06.960 --> 0:02:09.839 thought it was something in black panther like. People really 0:02:09.880 --> 0:02:12.200 didn't seem to have a good grip on what dark 0:02:12.280 --> 0:02:14.560 energy is, which is amazing, not just because it was 0:02:14.600 --> 0:02:18.040 a big discovery, but because it has huge consequences for 0:02:18.160 --> 0:02:21.480 our lives. Yeah, it's a great name. I mean, I 0:02:21.520 --> 0:02:23.639 think it's easy to see why people would confuse it 0:02:23.680 --> 0:02:26.640 with dark matter, they're both dark and that's right. It 0:02:26.720 --> 0:02:29.320 is a cool name, dark energy. It sounds so mysterious, though, 0:02:29.320 --> 0:02:31.560 you're right. In the in like the HR meeting where 0:02:31.560 --> 0:02:34.000 they decided what to call this weird physics thing, it 0:02:34.040 --> 0:02:36.079 should have considered the fact that dark matter and dark 0:02:36.160 --> 0:02:38.240 energy sounded like. I wonder if they do focus groups 0:02:38.240 --> 0:02:39.600 when they do that kind of thing. Do you think 0:02:39.600 --> 0:02:41.720 they thought, Hey, all those dark matter people get a 0:02:41.760 --> 0:02:44.560 ton of grant money. If we call our stark energy, 0:02:45.000 --> 0:02:47.160 we could also get some of that money. I'm sure. 0:02:47.480 --> 0:02:50.240 I'm sure that was the number one concern in their minds. Yeah, 0:02:50.320 --> 0:02:55.240 how will this play in my next grand proposal? Anyway? 0:02:55.280 --> 0:02:57.560 Let's tell people what dark energy is and why it's 0:02:57.600 --> 0:03:00.000 so important. Yeah, well, first of all, it's a huge, 0:03:00.040 --> 0:03:02.880 huge deal, right, Like, it's not like an obscure thing 0:03:03.040 --> 0:03:05.880 in physics. It's like a huge part of the universe. 0:03:06.120 --> 0:03:08.639 That's right. Most of the energy and the universe is 0:03:08.639 --> 0:03:13.520 actually taken up with dark energy, like sixties, right, that's right. Fully, 0:03:13.600 --> 0:03:16.239 two thirds of all the energy in the universe is 0:03:16.280 --> 0:03:20.080 devoted to this weird, mysterious force called dark energy, and 0:03:20.120 --> 0:03:22.040 that's about all we know about it. Like when you 0:03:22.080 --> 0:03:25.920 think of the universe and like atoms and protons and 0:03:25.960 --> 0:03:31.679 electrons and rocks, asteroids, planets, all those suns, hamsters and 0:03:31.840 --> 0:03:36.400 then the hamsters, yeah, hamsters, all that stuff out there 0:03:36.400 --> 0:03:39.760 in the universe. Stars. That's not all there is to 0:03:39.840 --> 0:03:42.760 it to the universe, right, A whole bunch of it 0:03:42.840 --> 0:03:45.560 is dark energy, that's right. Yeah, most of the stuff 0:03:45.560 --> 0:03:47.160 in the universe is not the kind of stuff that 0:03:47.200 --> 0:03:50.000 we see around us, as you were saying, even stars 0:03:50.000 --> 0:03:51.840 and planets and gas and dust, that all adds up 0:03:51.840 --> 0:03:55.680 to a tiny little slipper like five turns out. And 0:03:55.680 --> 0:03:57.520 this is the kind of stuff we've only learned recently. 0:03:57.760 --> 0:04:00.160 Most of the universe is weird. Stuff we never even 0:04:00.160 --> 0:04:02.600 thought about, we never even would have included in a 0:04:02.640 --> 0:04:05.240 pie chart of the universe thirty years ago. Is the 0:04:05.240 --> 0:04:08.760 biggest piece of the pie. It's this big kind of 0:04:08.800 --> 0:04:13.560 mysterious energy that's out there, that's right. So imagine, for example, 0:04:13.600 --> 0:04:16.360 you take like a cubic meter of space and you 0:04:16.440 --> 0:04:19.360 ask what's in it. Well, on average, you average over 0:04:19.360 --> 0:04:21.800 the whole universe that we can see, it has about 0:04:21.960 --> 0:04:26.039 five or six hydrogen atoms worth of energy. And most 0:04:26.080 --> 0:04:29.400 of that is not matter or or stuff that you're 0:04:29.400 --> 0:04:32.159 familiar with. Most of it is dark energy, and another 0:04:32.279 --> 0:04:34.360 big chunk of it is something called dark matter, which 0:04:34.400 --> 0:04:37.159 we can talk about it in another episode. Yeah, and 0:04:37.160 --> 0:04:39.320 and like dark energy is all around us, right, like 0:04:39.480 --> 0:04:42.400 right now, two thirds of the room right now that 0:04:42.440 --> 0:04:45.919 I'm in is filled with dark energy. That's right, most 0:04:45.920 --> 0:04:47.760 of the energy in the universe and most of the 0:04:47.800 --> 0:04:50.680 energy everywhere. And dark energy is not something that's out 0:04:50.680 --> 0:04:52.719 there in space. You're exactly right. It's here, it's with you. 0:04:52.800 --> 0:04:56.760 It's between your toes. It's getting refrigerator just other dark 0:04:56.800 --> 0:05:00.839 matter between my toes. Let's be honest. I don't think 0:05:00.839 --> 0:05:03.240 I want to know what he does, whether it's a 0:05:03.520 --> 0:05:06.240 cosmic mystery physics or not. Yeah, let's not let's not 0:05:06.240 --> 0:05:10.920 get into my toes on this. On this podcast, Daniel 0:05:11.000 --> 0:05:14.400 Jorge explained the universe and Jorge's toes. That's right, that's 0:05:14.440 --> 0:05:16.960 a winner right there. Um. But yeah, so it's a 0:05:17.040 --> 0:05:19.839 huge deal. It's all around this and it's causing the 0:05:19.920 --> 0:05:23.120 universe to explode. So that's that's kind of distressing. Yeah. 0:05:23.160 --> 0:05:25.280 Not only is it turned out to be most of 0:05:25.320 --> 0:05:28.640 the universe, it has huge consequences. Right. The universe is 0:05:28.680 --> 0:05:32.640 exploding in every direction, and in some ways dark energy 0:05:32.760 --> 0:05:35.280 is causing the universe to explode. Another way to think 0:05:35.320 --> 0:05:38.120 about it is that dark energy is our description of 0:05:38.160 --> 0:05:40.960 the fact that it is exploding. Like we saw the 0:05:41.040 --> 0:05:45.120 universe is exploding. We named that dark energy. It's not 0:05:45.200 --> 0:05:48.159 like there's two separate things where oh, here's dark energy, 0:05:48.160 --> 0:05:50.760 we know that's the thing. Here's it's cause it's more 0:05:50.800 --> 0:05:52.720 like dark energy is the description of the fact that 0:05:52.720 --> 0:05:55.720 the universe is exploding and we don't really know why. 0:05:55.960 --> 0:05:58.960 It's another name for the explosion of the universe. It's 0:05:58.960 --> 0:06:02.320 a fancy tide or our lack of understanding the explosion 0:06:02.320 --> 0:06:04.880 in the universe. It's like you don't understand something. You 0:06:04.960 --> 0:06:07.400 have the pr version. We could have called it what 0:06:07.560 --> 0:06:10.479 is going on with the universe? But dark energy sounds 0:06:10.520 --> 0:06:16.680 better w two F energy your t F universe man, Yeah, exactly. 0:06:19.720 --> 0:06:21.880 Well let's get into that. So how did how do 0:06:22.000 --> 0:06:24.800 we find out about this dark energy that's all around 0:06:24.880 --> 0:06:27.240 us and it's causing the universe to explode. Well, it's 0:06:27.279 --> 0:06:29.560 one of my favorite stories in science because it's a 0:06:29.600 --> 0:06:32.360 story where the answer was a surprise. You know, scientists 0:06:32.400 --> 0:06:35.159 went into it asking one question and learning something totally 0:06:35.200 --> 0:06:38.120 different about the universe. The question they started with was 0:06:38.600 --> 0:06:41.159 what is the history of the universe and what is 0:06:41.200 --> 0:06:45.560 the future of the universe? Like what's going to happen eventually? Yeah, exactly, 0:06:45.560 --> 0:06:48.920 Like is this whole universe gonna keep going forever? Is 0:06:48.960 --> 0:06:51.520 it going to compress into little dot? Do I have 0:06:51.680 --> 0:06:54.200 time to like write that novel I've always been wanting 0:06:54.240 --> 0:06:56.320 to write. You definitely have time to write that novel. 0:06:57.640 --> 0:06:59.719 I have no excuse. Is it another young adult novel? 0:06:59.720 --> 0:07:02.679 Because I have enough of those already. It's called dark 0:07:02.720 --> 0:07:07.880 youth dark, um dark. So you've got vampires, you've got 0:07:07.880 --> 0:07:13.920 where wolves have dark energy beings. Yeah. And so when physicists, 0:07:14.000 --> 0:07:16.400 when physicists want to predict the future, where they typically 0:07:16.440 --> 0:07:18.840 do is look into the past, try to understand what's 0:07:18.840 --> 0:07:22.000 happened so far, and then extrapolate so to figure out 0:07:22.080 --> 0:07:24.400 what the future of the universe was. They first looked 0:07:24.400 --> 0:07:26.880 into the past and said, what's been going on so far, 0:07:26.920 --> 0:07:33.600 and let's see what direction things are going in? Right, Like, um, uh, Like, 0:07:34.240 --> 0:07:36.400 how am I doing financially? Do I have more money 0:07:36.440 --> 0:07:39.080 now than I used to have money before? And that's 0:07:39.120 --> 0:07:40.920 a that will sort of tell me, what might I 0:07:41.000 --> 0:07:42.880 might expect in the future if I don't make ill 0:07:42.920 --> 0:07:45.600 advised decisions. That's right. Yeah, if your net worth has 0:07:45.600 --> 0:07:48.160 been rising, then you expected to keep going. What if 0:07:48.200 --> 0:07:50.640 your bank account is dropping every single month, then you 0:07:50.640 --> 0:07:53.720 can expect some sort of cataclysmic event in your near future. 0:07:53.800 --> 0:07:55.920 And I need to record more podcasts to make more money. 0:07:56.160 --> 0:07:59.760 That's right, that's right. And so in the physics world, 0:08:00.080 --> 0:08:02.000 we went back to the very beginning of the universe 0:08:02.040 --> 0:08:04.520 and said, okay, the universe started with a big bang, right, 0:08:04.920 --> 0:08:08.040 and things blew up from there. And the question people 0:08:08.080 --> 0:08:11.160 had in their minds was, you know, after the Big Bang, 0:08:11.200 --> 0:08:14.400 things flying out from that huge explosion. The question was, 0:08:14.720 --> 0:08:17.960 is there enough stuff in the universe for things to 0:08:18.240 --> 0:08:21.120 slow down, for the gravity from that stuff to slow 0:08:21.280 --> 0:08:25.200 things down, stop them, and then make them fall back in. 0:08:25.360 --> 0:08:28.160 So that was one possibility people were considering that the 0:08:28.240 --> 0:08:31.680 universe would stop, the expansion, would stop um and then 0:08:31.760 --> 0:08:34.480 come back into a big crunch. So like the stuff 0:08:34.520 --> 0:08:36.679 that flew out from the Big Bang, and now the 0:08:36.760 --> 0:08:39.319 question is like, are they going to keep flying off 0:08:39.880 --> 0:08:42.839 or maybe is there enough gravity pulling it all the 0:08:42.880 --> 0:08:46.880 stuff together that it's gonna like slow down and then 0:08:47.400 --> 0:08:51.080 pull back in, just kind of like how our solar 0:08:51.120 --> 0:08:53.839 system forms. Yeah, exactly. Most of the stuff that we 0:08:53.960 --> 0:08:56.680 know around us in the in the universe was formed 0:08:56.679 --> 0:08:59.640 by gravity. Right, Gravity gathered together rocks and dust and 0:08:59.720 --> 0:09:03.320 rubb and hamsters or whatever and coalesce it together. Right. 0:09:03.360 --> 0:09:06.200 That's why the Earth is round because that's gravity's work, 0:09:06.400 --> 0:09:09.360 tumbling everything towards a smooth surface. And that's how the 0:09:09.360 --> 0:09:12.640 Sun is formed, its gravity compressing dust and gas until 0:09:12.679 --> 0:09:14.760 it gets hot enough to burn. So gravity is is 0:09:14.880 --> 0:09:17.240 very powerful force and and has a lot of time. 0:09:17.800 --> 0:09:20.200 Um it's actually one of the weakest forces, but over 0:09:20.280 --> 0:09:23.000 cosmic scales and all this time, it has enough power 0:09:23.040 --> 0:09:25.959 to pull all this stuff together and compress it into objects. 0:09:26.000 --> 0:09:28.280 So people thought, maybe that's going to happen with the 0:09:28.320 --> 0:09:31.800 whole universe. Man, Like, maybe the whole universe is gonna 0:09:32.280 --> 0:09:35.280 come back together and compress back into a tiny dot. 0:09:35.320 --> 0:09:38.240 That would be pretty amazing, like a giant cloud. Does 0:09:38.360 --> 0:09:42.240 we all just kind of come get pulled together and 0:09:42.320 --> 0:09:45.480 we maybe come back down. That's one possible way that 0:09:45.520 --> 0:09:48.440 the future the universe could end up. That's right. Yeah, 0:09:48.440 --> 0:09:51.840 So option A was the big crunch. But people didn't know, 0:09:52.160 --> 0:09:54.480 like is there enough stuff in the universe? Is there 0:09:54.559 --> 0:09:57.320 enough gravity from that stuff to pull everything back together? 0:09:57.559 --> 0:10:00.200 Because it could totally have been that the explore ocean 0:10:00.280 --> 0:10:02.960 was more powerful essentially than the gravity, and the things 0:10:03.000 --> 0:10:06.080 spread out forever. Oh, that could happen, like things that 0:10:06.080 --> 0:10:09.319 are like a grenade out in space. It just blows 0:10:09.440 --> 0:10:14.120 up so violently that gravity is too weak to pull 0:10:14.200 --> 0:10:18.040 everything back together again. That's right, yeah, And that could 0:10:18.200 --> 0:10:19.600 that could have been the fate of the universe. It 0:10:19.640 --> 0:10:22.439 could be that the universe just keeps expanding, things spread 0:10:22.480 --> 0:10:25.760 out and slow down like gravity. Gravity is still slowing 0:10:25.800 --> 0:10:28.560 things down, but it doesn't have enough power to stop 0:10:28.600 --> 0:10:30.880 it and have it fall back in. And so it 0:10:30.920 --> 0:10:34.000 could be that just spreads out forever, getting cooler and 0:10:34.040 --> 0:10:37.040 cooler and more distant until something we call the heat 0:10:37.200 --> 0:10:40.760 death of the universe. That's when everything is the same temperature. Right, 0:10:40.800 --> 0:10:43.160 So physicists were like, are we ever going to be cool? 0:10:44.120 --> 0:10:49.520 That was a front question. We'll know in about to 0:10:49.559 --> 0:10:52.559 find out if physicists are ever cool. So that's I mean, 0:10:52.559 --> 0:10:55.320 that is a very significant question, right, Like we're we 0:10:55.400 --> 0:10:57.360 live in this universe. We kind of want to know, 0:10:57.520 --> 0:11:00.320 like where is this whole thing headed? Yeah, I wonder 0:11:00.400 --> 0:11:03.680 if it's interesting to most people. To me, as a physicist, 0:11:03.760 --> 0:11:05.920 I think it's one of the most interesting questions, Like 0:11:06.040 --> 0:11:09.319 what is the future of this whole amazing, beautiful experiment 0:11:09.360 --> 0:11:11.360 we're living in, you know, is it going to go 0:11:11.400 --> 0:11:13.599 on forever? Is it going to tear uself apart? Is 0:11:13.600 --> 0:11:16.440 it going to crunch together? Like? To me, that's a 0:11:16.480 --> 0:11:19.120 really interesting question, Like do we live at the peak 0:11:19.120 --> 0:11:21.280 of it? Or are we like in the after party, 0:11:21.480 --> 0:11:23.560 you know what I mean? Like, or are we or 0:11:23.600 --> 0:11:25.760 are our great grandchildren going to be like at the 0:11:25.800 --> 0:11:28.280 peak of the universe? Yeah? I think I think that's 0:11:28.280 --> 0:11:30.920 exactly right. And I think there's an issue of context there, right, 0:11:30.960 --> 0:11:33.640 Like as humans, we are always striving to understand the 0:11:33.720 --> 0:11:37.040 context of our existence. Why is this important? What's going on? 0:11:37.559 --> 0:11:40.280 And one of those questions is like is Earth at 0:11:40.320 --> 0:11:43.120 the center of the cosmos? Is Earth even important? And 0:11:43.160 --> 0:11:45.760 another question is like that but in time? Right, like 0:11:45.880 --> 0:11:49.040 are we living at an important time? What is the 0:11:49.120 --> 0:11:52.040 future going to be? Like where do we fit in? Yeah? 0:11:52.280 --> 0:11:54.040 Are people in a billion years going to look back 0:11:54.040 --> 0:11:56.280 and say, man, I wish I'd lived when Daniel L. Jorge, 0:11:56.280 --> 0:11:58.960 we're doing. They're awesome podcasts because those were the days, 0:11:59.080 --> 0:12:01.880 many the good old days of the universe. Yeah, this 0:12:01.920 --> 0:12:07.600 podcast is peak civilization, right, podcast is peak civilization. So 0:12:07.720 --> 0:12:21.720 state tuned state that one. Let's take a quick break. Yeah. 0:12:21.760 --> 0:12:24.080 So people were thinking about those two options, right, big 0:12:24.120 --> 0:12:28.240 crunch or heat death of the universe. So option A 0:12:28.520 --> 0:12:32.520 everything comes crashing back down. Option B things just gonna 0:12:32.559 --> 0:12:35.920 float away, yeah, exactly. And so what they wanted to 0:12:35.960 --> 0:12:38.040 do was look back in time because you can't actually 0:12:38.120 --> 0:12:40.800 see the future, but it's not that hard in physics 0:12:40.800 --> 0:12:43.600 to see the past, especially in astronomy. To see the past, 0:12:43.679 --> 0:12:45.600 all you have to do is look out into space, 0:12:46.040 --> 0:12:49.040 and everything you see in space happened in the past, 0:12:49.559 --> 0:12:52.520 just because it takes light time to get here from there. 0:12:52.679 --> 0:12:54.480 It's like back in the day when there was no 0:12:54.640 --> 0:12:58.880 email or internet, you would get your news from mail letters, right, 0:12:59.080 --> 0:13:04.319 And so the further away what did actually happened? At 0:13:04.360 --> 0:13:08.400 some point the internet did not exist, Daniel, what what what? 0:13:08.880 --> 0:13:14.000 It was all dark dark mail? Ye, dark mail. So yeah, 0:13:14.000 --> 0:13:16.280 so like the further away you get a letter the 0:13:16.360 --> 0:13:20.240 older that news was, yes, exactly. And some people think, oh, 0:13:20.240 --> 0:13:22.480 that's a bummer. I think it's actually pretty cool because 0:13:22.480 --> 0:13:24.600 it lets us look into the past, and so the 0:13:24.679 --> 0:13:26.720 further out you look, the further in the back in 0:13:26.720 --> 0:13:28.400 the past you can see. And the goal is to see, 0:13:28.440 --> 0:13:31.920 like how fast is stuff moving away from us, you know, 0:13:31.960 --> 0:13:34.240 the expansion of the universe. How fast is stuff moving 0:13:34.240 --> 0:13:36.440 away from us now? And how fast was it moving 0:13:36.440 --> 0:13:39.440 away from us earlier? So we could understand like, how 0:13:39.520 --> 0:13:41.280 is this changing, what is the faith going to be? 0:13:41.360 --> 0:13:45.080 Is its slowing down? How fast is it slowing down? Yeah, So, 0:13:45.120 --> 0:13:47.000 because like if the fate of the universe was for 0:13:47.080 --> 0:13:50.400 it to crunch down, then you would see things kind 0:13:50.440 --> 0:13:54.080 of expanding slower now than before. Like before you think 0:13:54.120 --> 0:13:56.280 this would be flying out, and now they would be 0:13:56.320 --> 0:13:58.920 kind of slowing down, And so we could expect things 0:13:58.920 --> 0:14:03.000 to crunch or if we measure things to be moving 0:14:03.000 --> 0:14:05.600 at about the same now as as they were before, 0:14:05.760 --> 0:14:07.720 then maybe the fate of the universe is just to 0:14:07.760 --> 0:14:11.120 kind of keep floating off and getting cooler exactly. And 0:14:11.160 --> 0:14:13.040 so that was the question. They were like, let's look 0:14:13.080 --> 0:14:15.439 and see how things are changing. How much is it 0:14:15.520 --> 0:14:18.080 slowing down? Is slowing down a lot, which means maybe 0:14:18.120 --> 0:14:20.440 big crunch are slowing down just a little, which means 0:14:20.480 --> 0:14:23.120 maybe heat death. That was the question they asked. But 0:14:23.120 --> 0:14:26.600 it's actually fascinating how they did it because it's tricky, right. 0:14:26.640 --> 0:14:29.160 In order to know how far back in the past 0:14:29.200 --> 0:14:31.360 you're looking, you have to know how far away a 0:14:31.440 --> 0:14:34.640 star is. And that's not easy to figure out, right, 0:14:34.720 --> 0:14:38.200 because like, if you look at a star, it's um, 0:14:38.240 --> 0:14:39.920 if it's dim, you don't know if it's just like 0:14:39.960 --> 0:14:42.040 a weak star or a really far away star. It's 0:14:42.040 --> 0:14:45.120 just a little point, right, it's hard to tell. You can't, like, um, 0:14:45.680 --> 0:14:47.640 tell how far away it is just from how bright 0:14:47.680 --> 0:14:49.880 that point is. That's right. You can't tell the difference 0:14:49.880 --> 0:14:52.760 between a star that's very bright and far away and 0:14:52.880 --> 0:14:55.960 very weak and close up. Um. We have some tricks, 0:14:56.160 --> 0:14:59.160 but none of them are really good. Um. The early days, 0:14:59.680 --> 0:15:01.960 UM people used to figure out how far away stars 0:15:01.960 --> 0:15:04.400 were by seeing how they shifted as their Earth went 0:15:04.440 --> 0:15:07.440 around the sun. Because if something was really close, then 0:15:07.480 --> 0:15:09.600 you could see it sliding back and forth as the 0:15:09.640 --> 0:15:12.080 Earth went around the Sun. That's called the parallax system. 0:15:12.120 --> 0:15:14.520 It's like how you triangulate with your eyes, right, like 0:15:14.560 --> 0:15:17.320 if yes, if something looks really different when you wink 0:15:17.400 --> 0:15:19.200 one eye and you wink the other one, then it 0:15:19.280 --> 0:15:22.040 must be pretty close. But if it doesn't change a 0:15:22.040 --> 0:15:26.280 lot when you wink between eyes, then uh, it's far away. Yeah, 0:15:26.360 --> 0:15:28.400 And so that's the original way people can figure out 0:15:28.440 --> 0:15:30.440 how far stuff away is. And then it was like 0:15:30.480 --> 0:15:33.240 in the nineteen twenties when Hubble figured out a new 0:15:33.240 --> 0:15:35.560 way to look at stuff in the sky and he 0:15:35.600 --> 0:15:39.000 found a particular kind of star called a seafid that 0:15:39.200 --> 0:15:42.480 rotated and its brightness was connected to how fast it 0:15:42.560 --> 0:15:45.000 was rotating, so you could figure out by measuring its 0:15:45.080 --> 0:15:47.360 rotation how bright it is, which told you how far 0:15:47.400 --> 0:15:49.440 away it was. So he was the first one to 0:15:49.440 --> 0:15:51.720 be able to see things that were further away. And 0:15:51.760 --> 0:15:54.200 he's actually the one who figured out not just that 0:15:54.240 --> 0:15:57.600 the universe is expanding. Before that, people thought, oh, the 0:15:57.680 --> 0:15:59.960 universe is just a bunch of stars hanging in space 0:16:00.000 --> 0:16:03.120 ace And he figured out two amazing things. One is 0:16:03.440 --> 0:16:06.320 the universe is expanding, and the other is that the 0:16:06.400 --> 0:16:09.400 universe is more than just our galaxy. And what do 0:16:09.480 --> 0:16:12.360 you mean more? He figured out that there were other galaxies. 0:16:12.720 --> 0:16:16.560 That's right, before Hubble, we thought there is just our galaxy, Like, 0:16:16.640 --> 0:16:20.600 imagine just a single galaxy floating in space. That's what 0:16:20.680 --> 0:16:24.240 people thought the universe was. He saw these little smudges 0:16:24.320 --> 0:16:26.080 up in the sky that people thought, oh, these should 0:16:26.120 --> 0:16:28.840 just dust or clouds or something turns, and that he 0:16:29.000 --> 0:16:32.040 proved by measuring the distance to them, that they were 0:16:32.160 --> 0:16:34.440 way too far away to be part of our galaxy. 0:16:34.640 --> 0:16:37.720 He proved that they were actually other galaxies, and that 0:16:37.800 --> 0:16:40.400 those galaxies who were running away from us. It must 0:16:40.440 --> 0:16:42.600 have been so mind blowing to be Hubble, you know, 0:16:42.640 --> 0:16:45.800 to have this moment of realization, Uh, to understand this 0:16:46.040 --> 0:16:49.680 huge context of our of our existence. Yeah, it must 0:16:49.680 --> 0:16:54.840 be very humble to be Hubble. You know, I don't 0:16:54.840 --> 0:16:57.280 know anything about Hubble, but a lot of these famous 0:16:57.280 --> 0:17:01.520 physicists were not the nicest guys. So is that you 0:17:01.720 --> 0:17:04.480 are their stories about Hubble. I don't know any of them, 0:17:04.680 --> 0:17:07.320 but if I had to guess any random famous physicist 0:17:07.359 --> 0:17:10.359 from history, they probably got there by not being the 0:17:10.440 --> 0:17:13.880 nicest of a person. Yeah, humble. Anyway, Hubble was able 0:17:13.920 --> 0:17:16.960 to see past our galaxy, but cosmically speaking, that's not 0:17:17.000 --> 0:17:18.679 far enough to be able to tell because that's just 0:17:18.720 --> 0:17:21.280 like the last you know, a little bit of the history. 0:17:21.600 --> 0:17:24.080 Then it was in the nineties nineties, people developed a 0:17:24.160 --> 0:17:26.919 powerful new technique that let them see much further, so 0:17:27.000 --> 0:17:29.360 we could tell how far away things were that were 0:17:29.480 --> 0:17:31.840 much much, much further, and that gave us a much 0:17:31.920 --> 0:17:36.280 deeper view, further than like the nearest galaxy, yeah, really 0:17:36.280 --> 0:17:39.320 far away galaxies. And that's a new kind of star 0:17:39.520 --> 0:17:43.400 that we started to understand, called a type one, a supernova. Right, 0:17:43.520 --> 0:17:46.560 they call him like the standard candles, right, exactly the 0:17:46.680 --> 0:17:49.320 standard candles because they act the same way everywhere in 0:17:49.320 --> 0:17:51.440 the universe. And so we can tell we know how 0:17:51.440 --> 0:17:54.160 bright they are, so based on how dim they are 0:17:54.320 --> 0:17:56.480 or how bright, we can tell how far away they are. 0:17:57.080 --> 0:18:00.400 So it was in the nineties people figured this thing out, like, look, 0:18:00.400 --> 0:18:02.880 we have a new standard candle that let's look much 0:18:02.960 --> 0:18:05.320 deeper into the history of the universe and how we 0:18:05.359 --> 0:18:07.680 can answer this question. We can figure out what is 0:18:07.720 --> 0:18:09.680 the future of the universe, What is it going to be? 0:18:09.840 --> 0:18:12.359 So most stars are you can't really tell, right, some 0:18:12.400 --> 0:18:14.399 of them are dim, some of them are far away. 0:18:14.480 --> 0:18:17.720 But there are this special type of star. It always 0:18:17.720 --> 0:18:21.280 explodes the same way, so that if you see it 0:18:21.920 --> 0:18:23.800 m really bright and must be closed, or if you 0:18:23.840 --> 0:18:25.960 see it really dim, it must be far away, right, 0:18:26.040 --> 0:18:27.800 that's right. And these are not just stars, as you said, 0:18:27.840 --> 0:18:30.919 these are supernova, right, they're the end of stars. Right. 0:18:30.960 --> 0:18:35.040 That's when stars collapse and implode, followed by huge, enormous 0:18:35.119 --> 0:18:38.919 cosmic explosion. And that explosion is super bright, like a 0:18:38.960 --> 0:18:43.000 single supernova can outshine the entire galaxy it's in, but 0:18:43.080 --> 0:18:45.520 just for a few days. It's like crazily burning up 0:18:45.560 --> 0:18:47.480 all of its fuel. It's like a flare. If you 0:18:47.520 --> 0:18:50.200 set your house on fire, it's brighter than the whole neighborhood, right, 0:18:50.040 --> 0:18:53.560 but not very long. So there were you know, people 0:18:53.560 --> 0:18:56.240 figure this out, and then people um sort of split 0:18:56.280 --> 0:18:58.159 into two teams. It was a team at Berkeley and 0:18:58.160 --> 0:19:00.480 there was a team in Australia, and and they were 0:19:00.600 --> 0:19:03.560 racing to discover to get as much data as possible 0:19:03.760 --> 0:19:06.560 because supernova are not regular. It's not like you know 0:19:06.600 --> 0:19:08.359 when it's going to happen. You have to just scan 0:19:08.520 --> 0:19:10.560 the sky and hope to see one. Then it developed 0:19:10.560 --> 0:19:13.359 special technology to look through all this telescope data and 0:19:13.359 --> 0:19:16.000 try to find new stars that were appearing in the sky, 0:19:16.000 --> 0:19:18.000 because that's what a supernova looks like, looks like a 0:19:18.040 --> 0:19:20.520 bright new star that appears and then it fades over 0:19:20.560 --> 0:19:22.880 a matter of days, and if you capture enough data 0:19:22.880 --> 0:19:25.080 about it, then you can learn about its brightness and 0:19:25.080 --> 0:19:27.400 figure out how far away it was. And so finally 0:19:27.560 --> 0:19:31.200 one of them discovered, like, hey, we have a measurement 0:19:31.359 --> 0:19:35.760 for how the universe is expanding, whether it's expanding faster 0:19:35.920 --> 0:19:38.320 or slower than before. Yeah, it took a took a 0:19:38.320 --> 0:19:40.399 couple of years for them to have enough data, and 0:19:40.400 --> 0:19:42.320 it was a scramble and think, I think those people 0:19:42.359 --> 0:19:44.560 must have been working twenty hour days in the seven 0:19:44.640 --> 0:19:47.119 days a week. Yeah, everyone wanted to be the first 0:19:47.160 --> 0:19:50.480 to say like, hey, here's that measurement exactly. Finally they 0:19:50.520 --> 0:19:53.760 had this plot of how fast the universe is expanding 0:19:53.960 --> 0:19:57.000 as a function of time. And what they discovered is 0:19:57.040 --> 0:20:00.000 that the universe is not slowing down a lot or 0:20:00.040 --> 0:20:02.720 slowing down a little. So it's not option A nor 0:20:02.760 --> 0:20:06.600 option B. That's right. The universe went for secret options. 0:20:06.680 --> 0:20:09.320 See secret Ope, you didn't even know it was on 0:20:09.359 --> 0:20:11.520 the menu. And that's what we got for dinner, right. 0:20:12.160 --> 0:20:14.480 And I love when the universe does that because it's like, oh, 0:20:14.520 --> 0:20:17.000 you silly little humans, you have no idea what even 0:20:17.119 --> 0:20:20.120 question you're asking? Right? You hadn't even thought about this answer. 0:20:20.320 --> 0:20:22.680