1 00:00:08,400 --> 00:00:13,160 Speaker 1: Hey, or hey, let's do a physics thought experiment. Do 2 00:00:13,200 --> 00:00:17,120 Speaker 1: I have to think about it? You have to have thoughts? Well, 3 00:00:17,200 --> 00:00:20,599 Speaker 1: does it involve you know, Einstein on a moving train 4 00:00:21,200 --> 00:00:23,560 Speaker 1: looking through a prison or something. No, No, we're going 5 00:00:23,680 --> 00:00:27,120 Speaker 1: bigger than that, Bigger than like a supermassive black hole, 6 00:00:27,320 --> 00:00:30,520 Speaker 1: even bigger. What could be bigger than billions of suns? Well, 7 00:00:30,640 --> 00:00:34,080 Speaker 1: imagine that you could visit the universe's control room and 8 00:00:34,159 --> 00:00:38,200 Speaker 1: just like turn something off. What would you remove from 9 00:00:38,200 --> 00:00:43,160 Speaker 1: our universe? I imagine that all the time, Daniel waited, 10 00:00:43,240 --> 00:00:45,480 Speaker 1: did you say what would I remove? Or who would 11 00:00:45,479 --> 00:00:48,960 Speaker 1: I remove? Let's not make it personal. What would you 12 00:00:49,040 --> 00:00:53,400 Speaker 1: remove from the universe? In that case? Probably Twitter? Twitter? 13 00:00:53,440 --> 00:00:57,240 Speaker 1: I would probably remove immediately. I thought you were going 14 00:00:57,280 --> 00:01:01,200 Speaker 1: to say, alarm clocks or emails? Yeah, those are pretty 15 00:01:01,240 --> 00:01:03,880 Speaker 1: bad too, deadlines if I can flip multiple switches, yeah, 16 00:01:03,920 --> 00:01:06,120 Speaker 1: they're all being flipped. Well, if that sounds good to you. 17 00:01:06,360 --> 00:01:08,600 Speaker 1: The next time we have an election, vote for Jorge 18 00:01:08,760 --> 00:01:28,600 Speaker 1: for Universe Control Room operating m Hi am Jorgemmay, cartoonists 19 00:01:28,640 --> 00:01:31,680 Speaker 1: and the creator of PhD comics. Hi, I'm Daniel, I'm 20 00:01:31,720 --> 00:01:35,080 Speaker 1: a particle of physicist, and I'm terrified to let Jorge 21 00:01:35,160 --> 00:01:37,400 Speaker 1: into the control room of the universe. Are you worried 22 00:01:37,440 --> 00:01:40,360 Speaker 1: I'm gonna do like a Homer Simpson and eat my 23 00:01:40,440 --> 00:01:44,240 Speaker 1: doughnuts and excellently press the red switch. No, I'm terrified 24 00:01:44,240 --> 00:01:47,280 Speaker 1: because you ask really good questions and so you'd be like, hmmm, 25 00:01:47,560 --> 00:01:49,880 Speaker 1: what happens Is I pushed this all the way up? 26 00:01:50,200 --> 00:01:52,080 Speaker 1: Or if I just flip all those knobs and the 27 00:01:52,080 --> 00:01:54,560 Speaker 1: physicists would be like, what, don't even think about that? 28 00:01:54,560 --> 00:01:58,720 Speaker 1: That's impossible. What if I flipped the switch on that 29 00:01:58,840 --> 00:02:02,040 Speaker 1: everyone that gets a physics agree, I would love that. 30 00:02:02,040 --> 00:02:04,440 Speaker 1: That is actually our goal, that's one of the missions 31 00:02:04,440 --> 00:02:07,280 Speaker 1: of this podcast, in fact, is to educate everybody out 32 00:02:07,280 --> 00:02:09,320 Speaker 1: there with a little bit of physics, to turn the 33 00:02:09,360 --> 00:02:11,800 Speaker 1: switch on in your head, to make you think about 34 00:02:11,800 --> 00:02:13,600 Speaker 1: the universe and to do a look out into the 35 00:02:13,639 --> 00:02:16,200 Speaker 1: cosmos and maybe a whole different way. One of my 36 00:02:16,240 --> 00:02:19,040 Speaker 1: proudest moments in this podcast was seeing somebody tweet that 37 00:02:19,080 --> 00:02:21,680 Speaker 1: they had learned more physics from our podcast than in 38 00:02:21,720 --> 00:02:25,760 Speaker 1: eight years as a PhD student in what But it 39 00:02:25,840 --> 00:02:28,280 Speaker 1: was on Twitter, so who knows if it was really Also, 40 00:02:28,440 --> 00:02:33,000 Speaker 1: could it have been one of your grad students or 41 00:02:33,080 --> 00:02:35,440 Speaker 1: my stock puppet account on Twitter. One of your students 42 00:02:35,440 --> 00:02:38,040 Speaker 1: is trying to tell you something, Daniel like, I hear 43 00:02:38,080 --> 00:02:41,600 Speaker 1: more from my professor through this podcast than in actual life. 44 00:02:41,600 --> 00:02:43,919 Speaker 1: I pay plenty of attention to my students, but thank 45 00:02:43,960 --> 00:02:46,240 Speaker 1: you for standing up for them. Well. Yeah, so, welcome 46 00:02:46,240 --> 00:02:48,920 Speaker 1: to our podcast, Daniel and Jorge Explained the Universe, a 47 00:02:48,960 --> 00:02:51,400 Speaker 1: production of I Heart Radio, in which we talk about 48 00:02:51,480 --> 00:02:55,680 Speaker 1: everything that's amazing in the universe, everything that's mysterious, everything 49 00:02:55,720 --> 00:02:57,880 Speaker 1: that we do know, everything that we don't know, everything 50 00:02:58,120 --> 00:03:00,840 Speaker 1: that we would like to know, and everything that Daniel 51 00:03:00,880 --> 00:03:02,960 Speaker 1: students want to ask him but can't seem to find 52 00:03:03,040 --> 00:03:05,040 Speaker 1: him in his office. For Yeah, I think they know 53 00:03:05,120 --> 00:03:07,359 Speaker 1: by now to pretend to be somebody else and then 54 00:03:07,360 --> 00:03:10,400 Speaker 1: send you a question. That's right because we think that 55 00:03:10,480 --> 00:03:13,000 Speaker 1: everything that you wonder about, everything that we wonder about, 56 00:03:13,040 --> 00:03:15,840 Speaker 1: everything that scientists are trying to figure out, We think 57 00:03:15,880 --> 00:03:19,240 Speaker 1: that those questions belong to everybody, and then everybody deserves 58 00:03:19,280 --> 00:03:21,600 Speaker 1: to know what's going on and what we know and 59 00:03:21,639 --> 00:03:24,359 Speaker 1: what we don't know. So our goal is to transport 60 00:03:24,440 --> 00:03:27,160 Speaker 1: you to the very forefront of human knowledge, and to 61 00:03:27,200 --> 00:03:30,200 Speaker 1: do it without using any fancy words, because there are 62 00:03:30,240 --> 00:03:32,880 Speaker 1: still a lot of questions out there in the universe. 63 00:03:33,200 --> 00:03:35,280 Speaker 1: There are a lot of big mysteries that scientists are 64 00:03:35,360 --> 00:03:39,040 Speaker 1: actively wondering about, and so scientists, for everyone, we should 65 00:03:39,040 --> 00:03:42,320 Speaker 1: all be involved in this quest to understand where we 66 00:03:42,360 --> 00:03:44,360 Speaker 1: are and how it is that we're here. Yeah, and 67 00:03:44,360 --> 00:03:46,720 Speaker 1: one of the biggest questions we have about the universe 68 00:03:46,880 --> 00:03:50,280 Speaker 1: is just why is it the way it is? Did 69 00:03:50,320 --> 00:03:52,480 Speaker 1: it have to be this way? Is there some rule 70 00:03:52,840 --> 00:03:55,480 Speaker 1: that tells us that the universe could only have been 71 00:03:55,520 --> 00:03:58,640 Speaker 1: this way or could it have been totally different? So 72 00:03:58,680 --> 00:04:01,360 Speaker 1: sometimes we look around with think, well, could the universe 73 00:04:01,400 --> 00:04:03,960 Speaker 1: work without this bit or that bit? Or what if 74 00:04:04,000 --> 00:04:07,640 Speaker 1: we flip these knobs with things still operate? Yeah, you mean, Daniel, 75 00:04:07,640 --> 00:04:10,640 Speaker 1: we can't just say it is what it is. It 76 00:04:10,720 --> 00:04:13,160 Speaker 1: definitely is what it is, But the question is why 77 00:04:13,360 --> 00:04:15,680 Speaker 1: is it what it is and not something else? Yeah? 78 00:04:15,680 --> 00:04:19,640 Speaker 1: Because I think you know, pondering these fundamental almost philosophical 79 00:04:19,720 --> 00:04:22,159 Speaker 1: questions is also a big part of physics, you know, 80 00:04:22,279 --> 00:04:25,000 Speaker 1: asking what if questions like why is it like that 81 00:04:25,080 --> 00:04:28,279 Speaker 1: and not something else? What if the universe was totally different? 82 00:04:28,440 --> 00:04:30,839 Speaker 1: Why isn't it what it Isn't that would be on 83 00:04:30,920 --> 00:04:35,279 Speaker 1: my tombstone? Right? Why you just made me think they're Daniel, 84 00:04:37,360 --> 00:04:40,120 Speaker 1: there's too many negatives in that one. Yeah, And we 85 00:04:40,160 --> 00:04:42,440 Speaker 1: are curious about that, and so we play these mind 86 00:04:42,480 --> 00:04:44,839 Speaker 1: games sometimes like do we need this bit or do 87 00:04:44,920 --> 00:04:46,839 Speaker 1: we need that bit? Or how do these two things 88 00:04:46,880 --> 00:04:49,600 Speaker 1: work together? And that's very helpful because it helps you 89 00:04:49,680 --> 00:04:53,120 Speaker 1: understand why we have the various pieces of the universe 90 00:04:53,160 --> 00:04:55,719 Speaker 1: that we have. We look out into the universe and 91 00:04:55,760 --> 00:04:57,919 Speaker 1: we see the way it works, and we try to 92 00:04:58,000 --> 00:05:00,280 Speaker 1: explain it, and we build up the minimal set of 93 00:05:00,320 --> 00:05:03,960 Speaker 1: bits that we need to explain everything that we see 94 00:05:04,040 --> 00:05:06,560 Speaker 1: in the universe. And so it's helpful to understand what 95 00:05:06,560 --> 00:05:08,440 Speaker 1: would happen if you yanked at one part of the 96 00:05:08,480 --> 00:05:11,039 Speaker 1: universe or yanked out another or turned something off. Ye. 97 00:05:11,320 --> 00:05:13,040 Speaker 1: And you know, it's not just kind of a fun 98 00:05:13,120 --> 00:05:15,480 Speaker 1: game to play, but it's also, you know, kind of 99 00:05:15,520 --> 00:05:19,760 Speaker 1: a fundamental way in which science is done, right. I mean, 100 00:05:20,360 --> 00:05:23,120 Speaker 1: when you ask yourself why something is like that, you 101 00:05:23,160 --> 00:05:25,640 Speaker 1: in science, you kind of have to ask yourself, what 102 00:05:25,960 --> 00:05:28,320 Speaker 1: if it wasn't like that? You know, I'm thinking about 103 00:05:28,320 --> 00:05:31,200 Speaker 1: the null hypothesis, Yeah, exactly. Sometimes you have to ask, 104 00:05:31,240 --> 00:05:34,040 Speaker 1: like do we really need this bit? Because the simpler 105 00:05:34,080 --> 00:05:37,359 Speaker 1: explanation is always preferred, and so if you can explain 106 00:05:37,720 --> 00:05:41,479 Speaker 1: the universe without some little extra you know, whiz bang 107 00:05:41,560 --> 00:05:44,040 Speaker 1: bit in your theory, then great. Like if you have 108 00:05:44,400 --> 00:05:47,040 Speaker 1: the current theory universe plus you have one with like 109 00:05:47,160 --> 00:05:50,279 Speaker 1: invisible space kittens, well, you don't really need the invisible 110 00:05:50,320 --> 00:05:54,440 Speaker 1: space kittens. They don't add anything to your theory. You 111 00:05:54,480 --> 00:05:57,760 Speaker 1: like the invisible space kittens, you don't need the invisible 112 00:05:57,760 --> 00:06:01,800 Speaker 1: space kitten. I would totally flip that swhich and that's 113 00:06:01,839 --> 00:06:04,240 Speaker 1: why we're not letting you into the control room. But 114 00:06:04,400 --> 00:06:06,480 Speaker 1: the point is we want the simplest theory, the one 115 00:06:06,520 --> 00:06:09,960 Speaker 1: that explains everything we see with a minimal set of ideas, 116 00:06:10,279 --> 00:06:14,240 Speaker 1: with the minimal set of numbers and details and complicated bits, 117 00:06:14,279 --> 00:06:17,840 Speaker 1: because we think, we hope the universe is simple, and 118 00:06:17,920 --> 00:06:20,640 Speaker 1: we can have long philosophical disagreements about whether the universe 119 00:06:20,640 --> 00:06:23,960 Speaker 1: should be beautiful and should be pretty, but the goal 120 00:06:24,040 --> 00:06:27,560 Speaker 1: of looking for simplicity has succeeded for a long time. Right, 121 00:06:27,600 --> 00:06:31,240 Speaker 1: I'm thinking simple space kittens. Then then then you can't 122 00:06:31,279 --> 00:06:33,599 Speaker 1: argue so single colors. For example, you don't have any 123 00:06:33,600 --> 00:06:37,440 Speaker 1: calico invisible space kittens. Alright, Well, on today's episode, we'll 124 00:06:37,440 --> 00:06:41,279 Speaker 1: be asking a really big what if question, maybe about 125 00:06:41,279 --> 00:06:43,320 Speaker 1: as big as you can ask about the universe, right, yeah, 126 00:06:43,360 --> 00:06:47,040 Speaker 1: I mean we're talking about the universe. What if it disappeared? 127 00:06:47,440 --> 00:06:51,000 Speaker 1: That's right. We are gonna let Jorge delete of the 128 00:06:51,080 --> 00:06:55,240 Speaker 1: universe Thanos could only do half the universe. Je has 129 00:06:55,279 --> 00:06:59,520 Speaker 1: even more power. That's right. I am even more inevitable. 130 00:06:59,800 --> 00:07:04,640 Speaker 1: I'm inevitably inevitable. Everybody out there, tremble in your headphones 131 00:07:04,920 --> 00:07:07,880 Speaker 1: that I'll just snap my fingers limping on my infinity 132 00:07:07,920 --> 00:07:12,520 Speaker 1: glove here, actually need to glove to get that's right. Yeah, 133 00:07:12,760 --> 00:07:16,560 Speaker 1: that's right. That's a whole second arc of the Avenger sequence, right, Avengers, 134 00:07:16,840 --> 00:07:20,280 Speaker 1: return of the Invisible Space Kittens, Jorges Army to destroy 135 00:07:20,320 --> 00:07:25,080 Speaker 1: the universe or maybe destroyed our Avengers after game post game, 136 00:07:25,920 --> 00:07:29,640 Speaker 1: still gaming anyways, So to be on the program, we'll 137 00:07:29,640 --> 00:07:37,760 Speaker 1: be asking the question what if dark matter and dark 138 00:07:37,920 --> 00:07:41,640 Speaker 1: energy disappear? Bom bom bomb or yes, the sound effect 139 00:07:41,720 --> 00:07:46,200 Speaker 1: would be like yow, I like that. You should do 140 00:07:46,240 --> 00:07:50,560 Speaker 1: that all the time here on the podcast. Due oh, 141 00:07:50,600 --> 00:07:52,040 Speaker 1: I make those sound effects when I talked to my 142 00:07:52,080 --> 00:07:55,600 Speaker 1: students in their meetings, and that's why they prefer to 143 00:07:55,600 --> 00:08:00,520 Speaker 1: listen to the podcast No No, But it's a really 144 00:08:00,560 --> 00:08:02,960 Speaker 1: fun question because, as you know, dark matter and dark 145 00:08:03,040 --> 00:08:06,080 Speaker 1: energy are huge for actions of the universe. They play 146 00:08:06,080 --> 00:08:09,200 Speaker 1: an enormous role, not just in how the universe look today, 147 00:08:09,240 --> 00:08:11,960 Speaker 1: but how it looked in its early stages when it 148 00:08:12,120 --> 00:08:15,960 Speaker 1: was a baby. Yeah, dark matter represents about of all 149 00:08:15,960 --> 00:08:18,680 Speaker 1: the mass and energy in the universe, and dark energy 150 00:08:18,840 --> 00:08:23,200 Speaker 1: represents about sixte right, Daniel, of all everything that there is. Yeah, 151 00:08:23,280 --> 00:08:26,320 Speaker 1: that's right. And we often get questions from listeners about 152 00:08:26,360 --> 00:08:29,240 Speaker 1: what that really means, like what's the denominator? You know, 153 00:08:29,320 --> 00:08:31,600 Speaker 1: if you don't know how big the universe is, how 154 00:08:31,640 --> 00:08:37,040 Speaker 1: can you say that dark matter is of what? And 155 00:08:37,200 --> 00:08:39,559 Speaker 1: it's a great question of the whole thing. You don't 156 00:08:39,600 --> 00:08:42,480 Speaker 1: need a denominate the whole thing. You don't need anominator 157 00:08:42,520 --> 00:08:44,600 Speaker 1: because we usually think about it in terms of density, 158 00:08:44,679 --> 00:08:48,160 Speaker 1: Like take any side blob of the universe. We're talking 159 00:08:48,160 --> 00:08:51,640 Speaker 1: about of that and not just of the matter, but 160 00:08:51,720 --> 00:08:55,360 Speaker 1: of the energy density, because remember that matter, that mass, 161 00:08:55,360 --> 00:08:58,000 Speaker 1: the stuff that makes me and you, it's just another 162 00:08:58,080 --> 00:09:00,720 Speaker 1: form of energy. And we talk go at the energy 163 00:09:00,760 --> 00:09:04,520 Speaker 1: density because that's really what controls the curvature of space. 164 00:09:04,600 --> 00:09:08,320 Speaker 1: In general, relativity it's not just stuff, but it's energy density. 165 00:09:08,480 --> 00:09:11,280 Speaker 1: So when we talk about this pie that five of 166 00:09:11,320 --> 00:09:13,480 Speaker 1: the universe is the kind of matter we're made out of, 167 00:09:13,520 --> 00:09:17,640 Speaker 1: in twenty seven is dark matter and sixty is dark energy. 168 00:09:17,920 --> 00:09:21,319 Speaker 1: We're really talking about the fractions of the energy density 169 00:09:21,360 --> 00:09:23,440 Speaker 1: of any volume of the universe, right, And so the 170 00:09:23,520 --> 00:09:27,040 Speaker 1: universe is really big or really small or infinite, it's 171 00:09:27,120 --> 00:09:29,360 Speaker 1: kind of still means the same thing. Yeah, let's just 172 00:09:29,440 --> 00:09:31,680 Speaker 1: talk about it without knowing the answer to that other 173 00:09:32,080 --> 00:09:37,120 Speaker 1: super massive, incredibly important question that we're amazingly totally clueless about. 174 00:09:37,160 --> 00:09:39,000 Speaker 1: And so we're asking the question, what would happen if 175 00:09:39,040 --> 00:09:41,160 Speaker 1: you take it away, like if you went to the 176 00:09:41,160 --> 00:09:43,440 Speaker 1: control room of the universe and just like flip the 177 00:09:43,600 --> 00:09:46,640 Speaker 1: off switch on those two things, that's right, and made 178 00:09:46,640 --> 00:09:50,120 Speaker 1: the dramatic sucking sound. And Daniel, do we mean like 179 00:09:50,520 --> 00:09:53,320 Speaker 1: if we trend them off now, or if we like 180 00:09:53,400 --> 00:09:55,360 Speaker 1: went back in time and took them out of the 181 00:09:55,400 --> 00:09:57,360 Speaker 1: birth of the universe. Yeah, well, immediately when you ask 182 00:09:57,440 --> 00:09:59,480 Speaker 1: that question, then I want to say, let's do all 183 00:09:59,520 --> 00:10:04,120 Speaker 1: of them, because they're all really fascinating different experiments, and 184 00:10:04,520 --> 00:10:06,920 Speaker 1: if you're going to understand the impact of these things 185 00:10:06,920 --> 00:10:09,280 Speaker 1: on the universe. You want to play different games, and 186 00:10:09,320 --> 00:10:11,520 Speaker 1: so yeah, we'll talk about if there had never been 187 00:10:11,600 --> 00:10:13,720 Speaker 1: dark matter and dark energy in the universe, what would 188 00:10:13,760 --> 00:10:16,400 Speaker 1: our universe look like? And also what would happen if 189 00:10:16,440 --> 00:10:20,640 Speaker 1: you just deleted them from the universe, like instantaneously. Right now, 190 00:10:20,880 --> 00:10:24,240 Speaker 1: we're going to cancel dark matter and dark energy. Right. 191 00:10:24,640 --> 00:10:26,760 Speaker 1: Have you heard what dark matter dark energy said a 192 00:10:26,800 --> 00:10:30,400 Speaker 1: hundred years ago? Boy, in modern context, it's embarrassing. We 193 00:10:30,520 --> 00:10:35,720 Speaker 1: heard of their workplace policies, oh man, exactly, they were 194 00:10:35,720 --> 00:10:38,120 Speaker 1: not very tolerant. But first, I was curious what our 195 00:10:38,160 --> 00:10:40,960 Speaker 1: listeners knew about this subject, and so, as usual, Daniel 196 00:10:41,000 --> 00:10:43,040 Speaker 1: went out there into the wilds of the Internet to 197 00:10:43,080 --> 00:10:47,120 Speaker 1: ask people what they thought would happen if dark matter 198 00:10:47,200 --> 00:10:50,480 Speaker 1: and dark energy disappear. So, if you're curious to play 199 00:10:50,520 --> 00:10:54,360 Speaker 1: intellectual thought experiments for future episodes, please write to us 200 00:10:54,400 --> 00:10:57,760 Speaker 1: two questions at Daniel and Jorge dot com. We'd love 201 00:10:57,920 --> 00:11:00,560 Speaker 1: to get your voice on the podcast. So think about 202 00:11:00,559 --> 00:11:02,400 Speaker 1: it for a second. What do you think would happen 203 00:11:02,640 --> 00:11:06,439 Speaker 1: if both of those big things disappeared. Here's what people 204 00:11:06,440 --> 00:11:10,400 Speaker 1: had to say if dark matter disappeared, assuming that it 205 00:11:10,440 --> 00:11:14,640 Speaker 1: did exist before and now it disappeared, then I would 206 00:11:14,679 --> 00:11:18,640 Speaker 1: assume that the galaxies would start to fall apart. The 207 00:11:18,720 --> 00:11:21,640 Speaker 1: solar systems will probably be okay because the gravity there 208 00:11:21,760 --> 00:11:23,959 Speaker 1: is enough to hold it together, but there wouldn't be 209 00:11:24,080 --> 00:11:31,479 Speaker 1: enough matter to hold the galaxies together. If dark energy disappeared, 210 00:11:32,240 --> 00:11:36,439 Speaker 1: then the universe would continue to expand it would stop accelerating. 211 00:11:36,520 --> 00:11:38,800 Speaker 1: I believe I'm gonna go ahead and assume that the 212 00:11:38,880 --> 00:11:41,679 Speaker 1: universe is is functioning the way it is now. I 213 00:11:41,679 --> 00:11:45,640 Speaker 1: would imagine if dark energy disappeared, there'd be enough momentum 214 00:11:46,000 --> 00:11:50,120 Speaker 1: of the expanding universe that it would continue expanding, and 215 00:11:50,160 --> 00:11:53,840 Speaker 1: that if dark matter disappeared, I don't know if there 216 00:11:53,840 --> 00:11:58,000 Speaker 1: would be enough regular matter to stop that expansion. Galaxies 217 00:11:58,000 --> 00:12:00,760 Speaker 1: would start flying apart, and possibly even and solar systems 218 00:12:00,800 --> 00:12:02,319 Speaker 1: might start flying apart. So would be kind of a 219 00:12:02,559 --> 00:12:05,400 Speaker 1: chaotic experience there. If we're saying dark energy is somehow 220 00:12:05,440 --> 00:12:08,679 Speaker 1: involved with the expansion of the universe, then I'm assuming 221 00:12:08,760 --> 00:12:12,600 Speaker 1: that that's not going to happen anymore. Plus, listening to 222 00:12:12,720 --> 00:12:17,880 Speaker 1: the latest episode on Black Holes, are not sure what's 223 00:12:17,920 --> 00:12:20,720 Speaker 1: actually going to happen there. But I'm not sure that 224 00:12:20,760 --> 00:12:23,440 Speaker 1: it actually interacts with us in any other way. That 225 00:12:23,520 --> 00:12:26,280 Speaker 1: we know of right now, So that's a total unknown 226 00:12:26,320 --> 00:12:30,480 Speaker 1: for me. Probably disaster. First of all, dark matter. Dark 227 00:12:30,559 --> 00:12:37,480 Speaker 1: matter is between twenty of the universe. That would be 228 00:12:37,640 --> 00:12:41,720 Speaker 1: pretty pretty bade. Everything would go crazy for sure if 229 00:12:42,040 --> 00:12:45,719 Speaker 1: dark matter disappears. We know that that is the thing 230 00:12:45,920 --> 00:12:49,360 Speaker 1: keeping us inside of our galaxy, and I did it, 231 00:12:49,720 --> 00:12:52,920 Speaker 1: and that galaxy is spinning, all the planets and all 232 00:12:52,960 --> 00:12:55,719 Speaker 1: the star starts with shootout and dark kind of is 233 00:12:55,760 --> 00:13:01,640 Speaker 1: the thing that's expanding University, So maybe Huntin stops or 234 00:13:01,800 --> 00:13:05,679 Speaker 1: maybe you know, to start to implode or something. All right, 235 00:13:05,760 --> 00:13:09,040 Speaker 1: it sounds like the main message here is disaster. That's right. 236 00:13:09,240 --> 00:13:12,000 Speaker 1: Nothing Good's right. The message is basically, keep Jorge out 237 00:13:12,040 --> 00:13:16,520 Speaker 1: of the control room called the Avengers, called the Avengers back, 238 00:13:18,600 --> 00:13:21,520 Speaker 1: knowing should have that much power, even the Avengers. I 239 00:13:21,520 --> 00:13:24,480 Speaker 1: think that was not thinking big enough, right, Yeah, exactly, 240 00:13:24,760 --> 00:13:27,319 Speaker 1: that was his problem. Yeah, he was not ambitious enough. 241 00:13:27,360 --> 00:13:30,120 Speaker 1: It actually wasn't one of the infinity stones of dark 242 00:13:30,160 --> 00:13:32,720 Speaker 1: matter or dark energy that they had, like a dark name. 243 00:13:32,960 --> 00:13:35,160 Speaker 1: I don't remember the physics of it, but one of 244 00:13:35,200 --> 00:13:38,400 Speaker 1: the cubes is supposed to be powered by dark energy, 245 00:13:38,440 --> 00:13:41,600 Speaker 1: if I remember, isn't one of the infinity stones, the 246 00:13:41,640 --> 00:13:45,199 Speaker 1: same cube that Thor was fighting over and that was 247 00:13:45,240 --> 00:13:48,120 Speaker 1: powered by dark energy. You're getting me excited here, Daniel. 248 00:13:48,160 --> 00:13:50,400 Speaker 1: We can spend the rest of the podcast going back 249 00:13:50,440 --> 00:13:55,160 Speaker 1: through the test rack and the power that's it is 250 00:13:55,200 --> 00:13:58,199 Speaker 1: powered by dark energy. That's the one. Yeah, but that 251 00:13:58,280 --> 00:14:00,840 Speaker 1: turned out to have a stone inside of it. Woe. Anyways, 252 00:14:00,920 --> 00:14:02,719 Speaker 1: back to physics. So not a lot of people have 253 00:14:02,720 --> 00:14:05,280 Speaker 1: predicted good things would happen. Most people seem to think 254 00:14:05,280 --> 00:14:07,679 Speaker 1: that the universe would sort of fall apart. Nobody is 255 00:14:07,720 --> 00:14:10,880 Speaker 1: in favor of this proposal. Everyone wants to keep those 256 00:14:10,920 --> 00:14:12,800 Speaker 1: things around as much as possible, which is why we're 257 00:14:12,840 --> 00:14:15,480 Speaker 1: doing it as a thought experiment and not in reality 258 00:14:17,160 --> 00:14:19,080 Speaker 1: that you know of, Daniel, And you know, there's a 259 00:14:19,080 --> 00:14:22,720 Speaker 1: long and great history of thought experiments. Einstein's development of 260 00:14:22,760 --> 00:14:25,840 Speaker 1: relativity was aided by thought experiments, just thinking what would 261 00:14:25,920 --> 00:14:28,800 Speaker 1: happen if and sometimes they're just very useful to get 262 00:14:28,840 --> 00:14:31,400 Speaker 1: you to think about the extreme situations. You know, you 263 00:14:31,440 --> 00:14:34,320 Speaker 1: can't really do the experiment of flying in a spaceship 264 00:14:34,360 --> 00:14:37,040 Speaker 1: at the speed of light and turning on a laser, 265 00:14:37,400 --> 00:14:39,760 Speaker 1: but you can think about what the rules that we 266 00:14:39,880 --> 00:14:42,800 Speaker 1: have suggest. You can think about what it would happen 267 00:14:42,960 --> 00:14:45,280 Speaker 1: if you did that experiment. Now, we'd love to actually 268 00:14:45,360 --> 00:14:47,280 Speaker 1: do it and to make those measurements, but even when 269 00:14:47,280 --> 00:14:49,520 Speaker 1: we can't, we can still do the thought experiment to 270 00:14:49,600 --> 00:14:51,960 Speaker 1: test the boundaries of the idea. Right, And you also 271 00:14:52,040 --> 00:14:54,960 Speaker 1: kind of do thought experiments before you do actual experiment, hope. 272 00:14:55,000 --> 00:14:57,840 Speaker 1: So like you probably work through all the possible ways 273 00:14:57,840 --> 00:14:59,600 Speaker 1: that it could go and then you that's how you 274 00:14:59,640 --> 00:15:01,880 Speaker 1: know to look for Yeah, we definitely thought about it 275 00:15:01,880 --> 00:15:04,440 Speaker 1: before we built the large change on collider. For example, 276 00:15:05,080 --> 00:15:08,040 Speaker 1: good will this destroy the world or not? We thought 277 00:15:08,080 --> 00:15:09,760 Speaker 1: about that, and we also thought about what we could 278 00:15:09,800 --> 00:15:11,960 Speaker 1: discover and how to build it, and so yeah, there's 279 00:15:12,000 --> 00:15:15,119 Speaker 1: a lot of four planning involved in all of these experiments. 280 00:15:15,120 --> 00:15:16,760 Speaker 1: All right, Well, just for those of you who might 281 00:15:16,760 --> 00:15:20,080 Speaker 1: not be familiar, let's recap really quickly what dark matter 282 00:15:20,160 --> 00:15:23,040 Speaker 1: and dark energy is. So let's start with dark matter. 283 00:15:23,160 --> 00:15:26,040 Speaker 1: Explain dark matter in three minutes before we delete it 284 00:15:26,040 --> 00:15:28,920 Speaker 1: from the universe. Let's remind people what it is. So 285 00:15:29,120 --> 00:15:33,040 Speaker 1: dark matter we know is matter. It's some invisible stuff 286 00:15:33,040 --> 00:15:35,520 Speaker 1: that's out there, and we know that it's matter and 287 00:15:35,560 --> 00:15:38,360 Speaker 1: that it's out there because we see its gravitational effects. 288 00:15:38,680 --> 00:15:42,560 Speaker 1: It's holding galaxies together that are otherwise spinning way too 289 00:15:42,640 --> 00:15:44,920 Speaker 1: fast to be held together by the gravity of the 290 00:15:44,960 --> 00:15:48,320 Speaker 1: stars that we can see. It controls the whole structure 291 00:15:48,320 --> 00:15:51,640 Speaker 1: of the universe, seeding the formation of galaxies and all 292 00:15:51,720 --> 00:15:54,560 Speaker 1: kinds of stuff. And we've measured that it's about twenty 293 00:15:54,680 --> 00:15:58,440 Speaker 1: seven percent of the energy budget of the universe, which 294 00:15:58,440 --> 00:16:01,320 Speaker 1: is about five times as as the normal matter, the 295 00:16:01,320 --> 00:16:03,800 Speaker 1: stuff that makes up stars and gas and planets and 296 00:16:03,840 --> 00:16:07,360 Speaker 1: bananas and all that good stuff, right and dark bananas obviously, 297 00:16:07,880 --> 00:16:09,960 Speaker 1: But it's a big deal. I mean, it's not just 298 00:16:10,040 --> 00:16:12,760 Speaker 1: like some small thing out there in space. It's it's 299 00:16:12,840 --> 00:16:17,360 Speaker 1: literally five times more than the kind of stuff that 300 00:16:17,440 --> 00:16:20,120 Speaker 1: we're made out of in stars and black and you know, 301 00:16:20,200 --> 00:16:23,360 Speaker 1: black holes and galaxies. Yeah, we are literally the tip 302 00:16:23,440 --> 00:16:26,200 Speaker 1: of the matter iceberg. And it's a wonderful lesson that 303 00:16:26,240 --> 00:16:28,960 Speaker 1: there's so much going on out there that we weren't 304 00:16:28,960 --> 00:16:31,560 Speaker 1: aware of until very recently, which means that there are 305 00:16:31,640 --> 00:16:35,120 Speaker 1: big surprises coming around the bend in the future. And 306 00:16:35,200 --> 00:16:37,520 Speaker 1: so we know that it's out there, we know that 307 00:16:37,560 --> 00:16:40,360 Speaker 1: it's matter. It's definitely made of stuff because it has gravity. 308 00:16:40,840 --> 00:16:42,160 Speaker 1: We don't know what it is. We don't know if 309 00:16:42,200 --> 00:16:43,920 Speaker 1: it's a particle. We don't know if it's something else. 310 00:16:43,960 --> 00:16:46,280 Speaker 1: We don't know, if it's seventies seven kinds of particles. 311 00:16:46,360 --> 00:16:47,920 Speaker 1: I don't know a lot about it other than that 312 00:16:48,000 --> 00:16:51,440 Speaker 1: it's dark and that it's matter. Hence the name dark matter, right, 313 00:16:51,440 --> 00:16:54,080 Speaker 1: and so that's dark matter, and so dark energy also, 314 00:16:54,200 --> 00:16:57,040 Speaker 1: how would you describe it? So dark energy is similar 315 00:16:57,080 --> 00:16:59,480 Speaker 1: to dark matter in the sense that it's important, it's 316 00:16:59,520 --> 00:17:01,720 Speaker 1: a big in the universe, and we don't know very 317 00:17:01,800 --> 00:17:04,679 Speaker 1: much about it. Otherwise, that's about all it has in 318 00:17:04,720 --> 00:17:08,000 Speaker 1: common with dark matter. Just basically the word dark dark 319 00:17:08,040 --> 00:17:10,720 Speaker 1: because we can't see it with visual light, right, Yeah, 320 00:17:10,760 --> 00:17:12,399 Speaker 1: we can't see it with visual light. And also we 321 00:17:12,440 --> 00:17:16,000 Speaker 1: just don't really understand it. Dark energy is not really 322 00:17:16,040 --> 00:17:19,040 Speaker 1: a thing. It's not something we understand, it's not something 323 00:17:19,040 --> 00:17:21,879 Speaker 1: we have a theory about. It's just the observation that 324 00:17:21,960 --> 00:17:26,600 Speaker 1: the universe is expanding and that that expansion is accelerating. 325 00:17:26,960 --> 00:17:30,159 Speaker 1: So space is getting bigger and bigger, but it's getting bigger, 326 00:17:30,320 --> 00:17:33,080 Speaker 1: faster and faster every year, and that takes energy. It 327 00:17:33,119 --> 00:17:36,359 Speaker 1: takes a lot of energy. And we only recently, like 328 00:17:37,400 --> 00:17:40,680 Speaker 1: years ago, discovered that this expansion is accelerating. So dark 329 00:17:40,800 --> 00:17:45,480 Speaker 1: energy is a description of that acceleration of the expansion. 330 00:17:45,680 --> 00:17:47,480 Speaker 1: We don't have a theory that describes that. We don't 331 00:17:47,480 --> 00:17:50,000 Speaker 1: have a model that makes it work. We've just seen 332 00:17:50,040 --> 00:17:52,440 Speaker 1: that this happens and we know that it's important. Right. 333 00:17:52,480 --> 00:17:54,280 Speaker 1: It's kind of like you're five year old when they 334 00:17:54,280 --> 00:17:55,680 Speaker 1: don't want to go to sleep and they're jumping in 335 00:17:55,760 --> 00:17:57,959 Speaker 1: the bed. You're like, where do they get this energy? Like, 336 00:17:58,119 --> 00:18:00,960 Speaker 1: it's not like they're glowing, they're just acting in a 337 00:18:01,000 --> 00:18:04,439 Speaker 1: funny way. That's right. But they both contribute to this pie. Right. 338 00:18:04,560 --> 00:18:07,960 Speaker 1: Dark energy takes a lot of energy. We can calculate 339 00:18:07,960 --> 00:18:10,000 Speaker 1: how much energy it takes to expand the universe and 340 00:18:10,040 --> 00:18:13,639 Speaker 1: to accelerate that expansion, and it's just under seventy percent 341 00:18:13,760 --> 00:18:16,960 Speaker 1: of the energy density of the universe. And dark matter 342 00:18:17,000 --> 00:18:19,720 Speaker 1: is and they fit together in this pie. And the 343 00:18:19,760 --> 00:18:22,920 Speaker 1: pie is important because various elements of the pie work 344 00:18:22,960 --> 00:18:27,000 Speaker 1: together to control whether the universe is expanding or contracting, 345 00:18:27,240 --> 00:18:30,320 Speaker 1: and whether stuff is being formed like galaxies and stars, 346 00:18:30,600 --> 00:18:32,560 Speaker 1: or whether everything is just sort of floating out their 347 00:18:32,600 --> 00:18:36,080 Speaker 1: diffuse and so as we'll learn, these two elements are 348 00:18:36,320 --> 00:18:39,600 Speaker 1: very important for the formation of our universe and to 349 00:18:39,720 --> 00:18:41,840 Speaker 1: keep it blowing up, or to make a contract, or 350 00:18:41,880 --> 00:18:44,160 Speaker 1: all of those things. So these are the most important 351 00:18:44,160 --> 00:18:48,040 Speaker 1: parameters into like determining the whole structure and the shape 352 00:18:48,040 --> 00:18:50,440 Speaker 1: and the size of the universe. Right, it's almost in 353 00:18:50,480 --> 00:18:52,240 Speaker 1: a way like if you like the universe way, it 354 00:18:52,320 --> 00:18:55,359 Speaker 1: is now like we are more expendable than dark matter 355 00:18:55,480 --> 00:18:58,000 Speaker 1: or dark energy. It's like you can take away all 356 00:18:58,000 --> 00:19:01,720 Speaker 1: the galaxies and stars and humans and bananas, and the 357 00:19:01,840 --> 00:19:04,000 Speaker 1: universe would be less affective than if you took out 358 00:19:04,000 --> 00:19:06,240 Speaker 1: one of these two things. That's right, If dark Corey 359 00:19:06,320 --> 00:19:09,520 Speaker 1: gets into the universe control room, Dark Daniel will say, yeah, sure, 360 00:19:09,600 --> 00:19:12,080 Speaker 1: turn off all the bananas another matter, It doesn't make 361 00:19:12,080 --> 00:19:17,440 Speaker 1: any difference. Let's just delete ourselves. But then who built 362 00:19:17,480 --> 00:19:20,760 Speaker 1: the control room Daniel? Well, you know, we don't know. 363 00:19:20,840 --> 00:19:24,520 Speaker 1: But we are a tiny, maybe irrelevant fraction of the universe, 364 00:19:24,520 --> 00:19:26,959 Speaker 1: and so we can't expect that everything is made in 365 00:19:27,040 --> 00:19:29,920 Speaker 1: our image. Right, All right, let's get into what would 366 00:19:29,960 --> 00:19:34,320 Speaker 1: happen to the universe if these two things suddenly disappeared. 367 00:19:34,640 --> 00:19:48,200 Speaker 1: But first let's take a quick break. All right, Daniel, 368 00:19:48,240 --> 00:19:51,000 Speaker 1: you've led me into the control room of the universe, 369 00:19:51,200 --> 00:19:53,920 Speaker 1: and I see a big switch here that says dark 370 00:19:54,000 --> 00:19:57,479 Speaker 1: matter with two options on or off. I'm gonna go 371 00:19:57,560 --> 00:19:59,720 Speaker 1: with off. Here, I'm gonna flip the switch. Are you 372 00:19:59,760 --> 00:20:05,359 Speaker 1: ready hold onto something? Click? All right, I've just made 373 00:20:05,440 --> 00:20:08,160 Speaker 1: dark matters. I hear. What's gonna happen? All right? Well, 374 00:20:08,200 --> 00:20:12,240 Speaker 1: it's important to know when we are in the universe simulation, like, 375 00:20:12,280 --> 00:20:14,320 Speaker 1: are we going to remove dark matter from the very 376 00:20:14,400 --> 00:20:17,080 Speaker 1: very beginning so there never was any, or are we 377 00:20:17,119 --> 00:20:19,280 Speaker 1: going to delete it? We're going to cancel dark matter 378 00:20:19,320 --> 00:20:23,359 Speaker 1: in the universe today. I guess that two different things 379 00:20:23,440 --> 00:20:26,040 Speaker 1: might happen, right, all right, So let's let's start with 380 00:20:26,080 --> 00:20:29,040 Speaker 1: the early universe. Let's say we pulled it back to 381 00:20:29,080 --> 00:20:31,800 Speaker 1: the future, went back to the early universe, and then 382 00:20:32,320 --> 00:20:35,879 Speaker 1: got rid of dark matter, but the universe be very different. 383 00:20:35,880 --> 00:20:39,040 Speaker 1: The universe would be really different fourteen billion years later 384 00:20:39,200 --> 00:20:41,680 Speaker 1: if there had never been any dark matter in it, 385 00:20:42,000 --> 00:20:44,399 Speaker 1: because dark matter is really the thing that makes the 386 00:20:44,520 --> 00:20:49,159 Speaker 1: universe interesting. Briefly, it's gravity is the reason that we 387 00:20:49,200 --> 00:20:53,160 Speaker 1: have formed stars and galaxies and all sorts of interesting stuff. 388 00:20:53,440 --> 00:20:55,800 Speaker 1: Like the gravity from our kind of matter is not 389 00:20:55,960 --> 00:21:00,320 Speaker 1: sufficient to pull together into interesting structures this early in 390 00:21:00,359 --> 00:21:05,400 Speaker 1: the universe. Without the gravitational assist of dark matter, because 391 00:21:05,680 --> 00:21:09,480 Speaker 1: I guess without the gravity that dark matter brings, things 392 00:21:09,560 --> 00:21:13,840 Speaker 1: wouldn't have clumped together as much or as interestingly, which 393 00:21:13,880 --> 00:21:15,880 Speaker 1: one are you saying, yeah, both of them. I mean, 394 00:21:15,920 --> 00:21:18,359 Speaker 1: the brief history of the universe is that you have 395 00:21:19,000 --> 00:21:22,960 Speaker 1: very small over densities, little places where stuff is denser 396 00:21:23,000 --> 00:21:26,240 Speaker 1: than other stuff that came out of quantum fluctuations in 397 00:21:26,280 --> 00:21:29,359 Speaker 1: the very early universe, and then gravity takes over and 398 00:21:29,440 --> 00:21:32,720 Speaker 1: stuff that's denser has more gravity attracts more stuff, which 399 00:21:32,760 --> 00:21:35,640 Speaker 1: makes more gravity, which attracts more stuff. It's a feedback cycle, 400 00:21:36,119 --> 00:21:38,560 Speaker 1: and what you need is stuff for that to happen. 401 00:21:38,960 --> 00:21:41,440 Speaker 1: And so if you have dark matter and it's five 402 00:21:41,520 --> 00:21:45,160 Speaker 1: times as much stuff as there is normal matter, then 403 00:21:45,160 --> 00:21:48,320 Speaker 1: that happens a lot faster. And something that people don't 404 00:21:48,320 --> 00:21:50,600 Speaker 1: typically understand is that dark matter is not just like 405 00:21:50,720 --> 00:21:54,679 Speaker 1: everywhere in the universe. It's clumped, are big blobs of it, 406 00:21:54,760 --> 00:21:58,320 Speaker 1: and those blobs are centered everywhere there is normal matter, 407 00:21:58,680 --> 00:22:01,960 Speaker 1: and it's not coincidence. Right. Think about dark matters forming 408 00:22:02,040 --> 00:22:05,200 Speaker 1: like depressions in the shape of the universe to collect 409 00:22:05,359 --> 00:22:08,719 Speaker 1: normal matter, so that gas and hydrogen and helium falls 410 00:22:08,760 --> 00:22:12,280 Speaker 1: into those depressions and then it squeezed together into stars 411 00:22:12,280 --> 00:22:15,320 Speaker 1: and galaxies, etcetera. Without them, it would be much smoother. 412 00:22:15,440 --> 00:22:17,720 Speaker 1: It take a lot longer for gravity to pull the 413 00:22:17,800 --> 00:22:21,040 Speaker 1: hydrogen together and to form stars and galaxies. That was 414 00:22:21,160 --> 00:22:25,560 Speaker 1: dark matter clumped initially, or was it out there in 415 00:22:25,640 --> 00:22:29,520 Speaker 1: the Big Bang pretty smooth or were there quantum fluctuations 416 00:22:29,560 --> 00:22:31,399 Speaker 1: in the dark matter as well? It was the quantum 417 00:22:31,400 --> 00:22:35,560 Speaker 1: fluctuations that caused any structure at all, Like everything else, 418 00:22:35,840 --> 00:22:38,399 Speaker 1: the universe would have started out perfectly smooth if not 419 00:22:38,520 --> 00:22:41,200 Speaker 1: for these quantum fluctuations, and then we would have dark matter, 420 00:22:41,280 --> 00:22:44,560 Speaker 1: even dark matter, Yeah, because dark matter and normal matter 421 00:22:44,600 --> 00:22:47,240 Speaker 1: were made in the Big Bang, right when we went 422 00:22:47,320 --> 00:22:49,840 Speaker 1: from really really hot and dense so that all the 423 00:22:49,840 --> 00:22:52,960 Speaker 1: fields were crazy, and then they broke down and created 424 00:22:52,960 --> 00:22:55,960 Speaker 1: the particles as the universe started to expand and cooled. 425 00:22:56,240 --> 00:22:59,639 Speaker 1: So they were all made essentially during this initial expansion 426 00:22:59,720 --> 00:23:02,119 Speaker 1: of the universe. But as you say, it would have 427 00:23:02,119 --> 00:23:05,240 Speaker 1: been perfectly smooth without those quantum fluctuations, and so dark 428 00:23:05,280 --> 00:23:09,680 Speaker 1: matter like accentuates it, like exaggerates the effect of these fluctuations, 429 00:23:09,720 --> 00:23:12,120 Speaker 1: and it speeds things up. If you do a simulation 430 00:23:12,240 --> 00:23:14,840 Speaker 1: of the universe without dark matter, we've literally done this. 431 00:23:15,160 --> 00:23:18,119 Speaker 1: Then you just don't get stars and galaxies fourteen billion 432 00:23:18,200 --> 00:23:21,439 Speaker 1: years into the universe, but you get them eventually, Like 433 00:23:21,520 --> 00:23:25,400 Speaker 1: it's the effect of dark matter just speeding things up, 434 00:23:25,640 --> 00:23:28,399 Speaker 1: or is it like we would never clump together as 435 00:23:28,400 --> 00:23:30,320 Speaker 1: a galaxy. Well, it depends a little bit on what's 436 00:23:30,359 --> 00:23:33,480 Speaker 1: going on with dark energy. It speeds things up, right, 437 00:23:33,520 --> 00:23:37,560 Speaker 1: And so given enough time without dark energy expanding the universe, 438 00:23:37,600 --> 00:23:40,439 Speaker 1: then yeah, it would form these gravitational structures and you 439 00:23:40,440 --> 00:23:42,800 Speaker 1: would get stars and galaxies. But there's a bit of 440 00:23:42,840 --> 00:23:45,479 Speaker 1: a race here, right. Dark energy is coming on the 441 00:23:45,480 --> 00:23:48,560 Speaker 1: scene and it's pulling the universe apart. It's making it 442 00:23:48,640 --> 00:23:51,240 Speaker 1: harder for gravity to form structures. So we got a 443 00:23:51,280 --> 00:23:53,639 Speaker 1: little bit of a window there right before dark energy 444 00:23:53,960 --> 00:23:56,639 Speaker 1: yanks the universe apart. It makes everything too far apart 445 00:23:56,680 --> 00:23:59,159 Speaker 1: to do anything interesting. You've got a window there to 446 00:23:59,240 --> 00:24:02,520 Speaker 1: form interest structures. So you don't have infinite time to 447 00:24:02,720 --> 00:24:04,800 Speaker 1: get stuff done. You've got a deadline. I mean you 448 00:24:04,880 --> 00:24:07,840 Speaker 1: have fourteen billion years, but you still got a deadline, right, Well, 449 00:24:07,840 --> 00:24:10,879 Speaker 1: assuming that dark energy keeps going, that's right, Assuming that 450 00:24:10,960 --> 00:24:12,880 Speaker 1: dark energy keeps going and that you know, you don't 451 00:24:12,880 --> 00:24:14,879 Speaker 1: stumble into the control room and turn it off or 452 00:24:14,920 --> 00:24:18,800 Speaker 1: accidentally double it or something. Stay tuned, Stay tuned. That's 453 00:24:18,800 --> 00:24:21,120 Speaker 1: the last part of the podcast. So we wouldn't get 454 00:24:21,480 --> 00:24:24,520 Speaker 1: interesting structures. So what would the universe look like today? 455 00:24:24,600 --> 00:24:27,920 Speaker 1: It would just look sparser, like there wouldn't be like 456 00:24:28,280 --> 00:24:30,960 Speaker 1: galaxies and stars will be more spread out apart, or 457 00:24:30,960 --> 00:24:33,040 Speaker 1: there'll be less stars. Yeah, we would essentially just be 458 00:24:33,160 --> 00:24:36,359 Speaker 1: earlier in the development of structure. And so whereas in 459 00:24:36,400 --> 00:24:39,080 Speaker 1: our universe we had the first population of stars form 460 00:24:39,119 --> 00:24:41,440 Speaker 1: in less than a billion years after the Big Bang, 461 00:24:41,720 --> 00:24:45,080 Speaker 1: that would have happened much later, and galaxies formed, you know, 462 00:24:45,359 --> 00:24:47,520 Speaker 1: in the first billion years or so. That would also 463 00:24:47,560 --> 00:24:50,159 Speaker 1: happen much much later. And so at this point in 464 00:24:50,200 --> 00:24:52,520 Speaker 1: the universe. It depends a little bit on the details 465 00:24:52,520 --> 00:24:54,720 Speaker 1: of how are you modeling dark energy, But we would 466 00:24:54,760 --> 00:24:58,439 Speaker 1: probably have some stars, but not big complicated galaxies like 467 00:24:58,480 --> 00:25:01,080 Speaker 1: we have today. So dark matters like this, steroids kind 468 00:25:01,080 --> 00:25:03,840 Speaker 1: of of the growth of the universe. All right, I 469 00:25:03,840 --> 00:25:07,560 Speaker 1: thought the universe was organic and you know, hormone free, 470 00:25:07,600 --> 00:25:10,040 Speaker 1: but I guess even the universe dopes a little. That's right. 471 00:25:10,040 --> 00:25:13,200 Speaker 1: Market pressures, man, market pressures, alright, So then the other 472 00:25:13,240 --> 00:25:15,840 Speaker 1: scenario that's interesting is like, what have you turned off 473 00:25:15,920 --> 00:25:18,280 Speaker 1: dark matter? Now? Like we are where we are now, 474 00:25:18,359 --> 00:25:20,680 Speaker 1: it is what it is, but then suddenly something happened 475 00:25:20,680 --> 00:25:23,240 Speaker 1: to dark matter. That's right. Say you have had dark 476 00:25:23,280 --> 00:25:26,880 Speaker 1: matter that super charged the acceleration of structure in the universe, 477 00:25:26,920 --> 00:25:29,520 Speaker 1: gave us stars and galaxies, and then you deleted it 478 00:25:29,680 --> 00:25:32,840 Speaker 1: Santos style from the universe. Well, you know, the structures 479 00:25:32,840 --> 00:25:35,960 Speaker 1: that we have now depend on dark matter. It's not 480 00:25:36,040 --> 00:25:38,480 Speaker 1: just like, well, we needed dark matter to get where 481 00:25:38,480 --> 00:25:40,200 Speaker 1: we are, but now that we're rich and famous, we 482 00:25:40,240 --> 00:25:43,280 Speaker 1: could forget about our friends from our hometown. We still 483 00:25:43,359 --> 00:25:47,440 Speaker 1: need dark matter because it's holding our galaxy together. Like 484 00:25:47,480 --> 00:25:50,840 Speaker 1: our galaxy is spinning, right, and things that are spinning 485 00:25:51,080 --> 00:25:54,240 Speaker 1: tend to fly apart if there's not something holding them together. 486 00:25:54,720 --> 00:25:56,560 Speaker 1: Like we say often in the podcast, you put ping 487 00:25:56,640 --> 00:25:58,720 Speaker 1: pong balls on a merry go round and spin it, 488 00:25:58,960 --> 00:26:01,880 Speaker 1: ping pong balls fly out. The reason that the stars 489 00:26:01,920 --> 00:26:05,119 Speaker 1: in our galaxy, which is spinning, don't fly out into 490 00:26:05,240 --> 00:26:08,760 Speaker 1: intergalactic space is because gravity is holding them together, and 491 00:26:08,920 --> 00:26:13,400 Speaker 1: mostly that's dark matter. So if you deleted dark matter 492 00:26:13,480 --> 00:26:16,640 Speaker 1: from the galaxy, then it'd be like as if you 493 00:26:16,720 --> 00:26:19,359 Speaker 1: suddenly turned the merry go around on five times as fast, 494 00:26:19,880 --> 00:26:22,480 Speaker 1: and you know, the stuff in the outer ring of 495 00:26:22,520 --> 00:26:26,040 Speaker 1: the galaxy would get tossed out into intergalactic space. There 496 00:26:26,040 --> 00:26:28,199 Speaker 1: wouldn't be enough gravity to hold it today. Would it 497 00:26:28,240 --> 00:26:30,399 Speaker 1: just fly off or would it just you know, the 498 00:26:30,400 --> 00:26:32,760 Speaker 1: galaxy would just get bigger in terms of things being 499 00:26:32,800 --> 00:26:34,840 Speaker 1: more spread out. It would get bigger. But the stuff 500 00:26:34,880 --> 00:26:38,439 Speaker 1: on the outside would essentially have escape velocity suddenly, so 501 00:26:38,480 --> 00:26:41,440 Speaker 1: they would get tossed into intergalactic space. We would lose 502 00:26:41,480 --> 00:26:45,600 Speaker 1: all those stars in the sort of exerbs of the galaxy. Well, 503 00:26:45,400 --> 00:26:49,320 Speaker 1: we don't really need those stars to be there's a 504 00:26:49,320 --> 00:26:51,879 Speaker 1: lot of crucial votes in those districts, man, so be careful. 505 00:26:51,920 --> 00:26:54,919 Speaker 1: Which is it's a lot of politics here today, Daniel. 506 00:26:55,440 --> 00:26:58,200 Speaker 1: But your fate depends sort of on your distance from 507 00:26:58,200 --> 00:27:00,760 Speaker 1: the center of the galaxy. If you're the very edge 508 00:27:00,760 --> 00:27:03,200 Speaker 1: of the galaxy, you're getting tossed out into space. You're 509 00:27:03,200 --> 00:27:06,080 Speaker 1: becoming a rogue star, which is, hey, maybe not that bad. Like, 510 00:27:06,200 --> 00:27:08,800 Speaker 1: what do you really need the galaxy for anyway? You know, 511 00:27:08,840 --> 00:27:11,720 Speaker 1: if you believe in in limited galaxies, then maybe that's 512 00:27:11,760 --> 00:27:13,840 Speaker 1: good for your philosophy. Well, what would happen to us 513 00:27:13,840 --> 00:27:16,880 Speaker 1: in particular, like would our solar system be affected at all? 514 00:27:17,000 --> 00:27:19,399 Speaker 1: Like would life go on the same for us, or 515 00:27:19,400 --> 00:27:21,320 Speaker 1: would we also fall apart. Well, we're in so of 516 00:27:21,359 --> 00:27:25,120 Speaker 1: that middle region and we would stay still gravitationally bound 517 00:27:25,160 --> 00:27:27,720 Speaker 1: to the main galaxy. But we get a little further 518 00:27:27,800 --> 00:27:30,760 Speaker 1: from the center, and probably what would happen is that 519 00:27:31,000 --> 00:27:33,399 Speaker 1: all the stars in our vicinity would clump together to 520 00:27:33,480 --> 00:27:36,760 Speaker 1: form basically like a little dwarf galaxy. You may not 521 00:27:36,840 --> 00:27:40,199 Speaker 1: be aware, but our galaxy has little satellites, like you 522 00:27:40,240 --> 00:27:43,440 Speaker 1: know our planet has a moon, right, our galaxy has 523 00:27:43,440 --> 00:27:47,119 Speaker 1: its own satellites, things that orbited called dwarf galaxies, little 524 00:27:47,240 --> 00:27:51,280 Speaker 1: clusters of stars that form many galaxies. So probably our 525 00:27:51,359 --> 00:27:53,600 Speaker 1: son would end up in one of these little clumps 526 00:27:53,760 --> 00:27:57,359 Speaker 1: that would be orbiting the old core of the Milky Way, really, 527 00:27:57,359 --> 00:28:00,000 Speaker 1: but maybe further out or something further out, So instead 528 00:28:00,040 --> 00:28:02,520 Speaker 1: of being like in the suburbs, would be a little 529 00:28:02,560 --> 00:28:05,280 Speaker 1: town out deep in the wilderness. So you're saying, without 530 00:28:05,359 --> 00:28:08,320 Speaker 1: dark matter, you would get more of these satellite galaxies. 531 00:28:08,480 --> 00:28:10,800 Speaker 1: Why would we get more Well, because the middle part 532 00:28:10,800 --> 00:28:13,480 Speaker 1: of the galaxy, this middle band where we live, wouldn't 533 00:28:13,480 --> 00:28:16,480 Speaker 1: be held into the galaxy anymore sort of get spread 534 00:28:16,520 --> 00:28:19,240 Speaker 1: out and instead of having being tossed all the way 535 00:28:19,240 --> 00:28:21,359 Speaker 1: into space, we don't have enough velocity for that, We 536 00:28:21,400 --> 00:28:25,760 Speaker 1: don't have escape velocity. We become gravitationally bound to the galaxy, 537 00:28:25,800 --> 00:28:28,440 Speaker 1: but in sort of a clump, and so this middle 538 00:28:28,480 --> 00:28:30,200 Speaker 1: part of the galaxy we sort of break up into 539 00:28:30,240 --> 00:28:32,840 Speaker 1: a bunch of little galaxies that are then orbiting the 540 00:28:32,840 --> 00:28:35,600 Speaker 1: old poor All right, Well, it sounds like if we 541 00:28:35,640 --> 00:28:37,880 Speaker 1: took it out early in the universe, we wouldn't be here. 542 00:28:38,360 --> 00:28:41,320 Speaker 1: The universe would look really different. But if he took 543 00:28:41,320 --> 00:28:44,040 Speaker 1: it out today, you know, daily life, We mean, we 544 00:28:44,040 --> 00:28:46,920 Speaker 1: we would sort of orbit around things differently, but it 545 00:28:46,920 --> 00:28:49,240 Speaker 1: maybe wouldn't affect us in our daily lives. Yeah, we're 546 00:28:49,240 --> 00:28:51,800 Speaker 1: almost not affected at all by the structure of the galaxy. 547 00:28:51,840 --> 00:28:53,840 Speaker 1: Doesn't really matter to us at all whether those other 548 00:28:53,920 --> 00:28:57,400 Speaker 1: stars are there. You know, we're dominated by the experience 549 00:28:57,440 --> 00:28:59,840 Speaker 1: of the Sun, but whether there are other stellar n 550 00:29:00,120 --> 00:29:02,560 Speaker 1: verse is not really a big deal. And you know, 551 00:29:02,600 --> 00:29:06,600 Speaker 1: it affects maybe our prospects for galaxy spanning civilizations once 552 00:29:06,640 --> 00:29:08,440 Speaker 1: in the future if we end up in a little 553 00:29:08,520 --> 00:29:11,440 Speaker 1: dwarf galaxy further from the main core. But you know, 554 00:29:11,480 --> 00:29:14,000 Speaker 1: if our ambitions are closer to home, then it doesn't 555 00:29:14,040 --> 00:29:17,200 Speaker 1: really change our lives if dark matter is deleted today, right? 556 00:29:17,320 --> 00:29:19,320 Speaker 1: Or I wonder how long before we would even notice 557 00:29:19,400 --> 00:29:21,160 Speaker 1: dark matter was gone? Oh my gosh, are you Are 558 00:29:21,160 --> 00:29:22,800 Speaker 1: you trying to admit? Are you trying to confess to 559 00:29:22,840 --> 00:29:26,240 Speaker 1: having done something last night? Where are they going to notice? 560 00:29:26,560 --> 00:29:28,680 Speaker 1: I'm like the bad guy and Watchman. It's like I 561 00:29:28,720 --> 00:29:33,200 Speaker 1: flipped the switch twenty four hours ago, Daniel. This is 562 00:29:33,240 --> 00:29:35,360 Speaker 1: the modern version of the tell tale heart, right, can 563 00:29:35,400 --> 00:29:39,760 Speaker 1: anybody tell? They're all looking at me? Yeah, Like, like 564 00:29:39,800 --> 00:29:42,040 Speaker 1: how long ago could I have flipped the switch before 565 00:29:42,120 --> 00:29:44,120 Speaker 1: we even notice? And that's a good question, and it 566 00:29:44,160 --> 00:29:46,600 Speaker 1: goes to like how well we know the structure of 567 00:29:46,640 --> 00:29:49,880 Speaker 1: our galaxy, which is a whole fascinating podcast topic. We 568 00:29:49,920 --> 00:29:52,720 Speaker 1: have schedules for a couple of weeks from now, but 569 00:29:52,760 --> 00:29:54,640 Speaker 1: we know that the structure of the galaxy pretty well, 570 00:29:54,640 --> 00:29:57,080 Speaker 1: and we can tell the distance to nearby stars, and 571 00:29:57,120 --> 00:29:59,920 Speaker 1: so if that's suddenly changed, we we would be able 572 00:29:59,920 --> 00:30:01,920 Speaker 1: to tell. But not for a few years, right, because 573 00:30:01,920 --> 00:30:05,080 Speaker 1: the information we're getting is years old, because the closest 574 00:30:05,080 --> 00:30:07,440 Speaker 1: stars are a few light years away and most of 575 00:30:07,440 --> 00:30:10,080 Speaker 1: the rest of the galaxy is five ten a hundred 576 00:30:10,080 --> 00:30:12,200 Speaker 1: thousand light years away, so it would be a while 577 00:30:12,280 --> 00:30:15,200 Speaker 1: before we actually saw hundreds of years or something, right, Yeah, 578 00:30:15,200 --> 00:30:17,120 Speaker 1: it could be hundreds or thousands of years before we 579 00:30:17,120 --> 00:30:19,520 Speaker 1: figure that out. Before we're like, holl hey, what did 580 00:30:19,520 --> 00:30:22,680 Speaker 1: you do? Or is great great great great great grandchildren 581 00:30:22,760 --> 00:30:24,560 Speaker 1: or to be held to account? So what would it 582 00:30:24,600 --> 00:30:26,720 Speaker 1: look like? Would we see less stars out in space 583 00:30:26,720 --> 00:30:28,360 Speaker 1: when we looked at the nice guy? Yeah, we would 584 00:30:28,400 --> 00:30:31,040 Speaker 1: see less stars out in space, and we'd be separated 585 00:30:31,040 --> 00:30:33,640 Speaker 1: from the main core of the galaxy. Now, the core 586 00:30:33,640 --> 00:30:36,320 Speaker 1: of the galaxy wouldn't change very much because it's got 587 00:30:36,360 --> 00:30:39,360 Speaker 1: so much gravity already in the supermassive black hole would 588 00:30:39,360 --> 00:30:41,640 Speaker 1: hang on to that. Instead of seeing the Milky Way 589 00:30:41,840 --> 00:30:44,080 Speaker 1: as a band across the sky, we would see the 590 00:30:44,120 --> 00:30:47,880 Speaker 1: core of the galaxy in our sky. Be pretty spectacular. Actually, 591 00:30:48,400 --> 00:30:50,480 Speaker 1: it would get more intense. Maybe, yeah, I might get 592 00:30:50,520 --> 00:30:53,560 Speaker 1: more intense. All right, Well that's um dark Matter. Thank 593 00:30:53,560 --> 00:30:55,880 Speaker 1: you for playing dark Matter. We like what you're doing. 594 00:30:55,920 --> 00:30:59,000 Speaker 1: We'll keep it. I guess I vote yes on dark 595 00:31:00,760 --> 00:31:02,840 Speaker 1: You don't even know what it is, Daniel, I don't 596 00:31:02,840 --> 00:31:04,360 Speaker 1: know what it is, but I want to keep it. 597 00:31:04,360 --> 00:31:07,239 Speaker 1: Wrong I like it, I fear changed. Right, let's talk 598 00:31:07,240 --> 00:31:09,840 Speaker 1: about what would happen if we took dark energy away? 599 00:31:09,880 --> 00:31:24,320 Speaker 1: But first let's take another quick break. All right, Dan, 600 00:31:24,520 --> 00:31:26,720 Speaker 1: we're talking about what would happen if we took out 601 00:31:26,800 --> 00:31:30,080 Speaker 1: these big chunks with the universe way dark matter and 602 00:31:30,200 --> 00:31:32,920 Speaker 1: dark energy, And so let's talk about what would happen 603 00:31:32,960 --> 00:31:36,520 Speaker 1: if I made dark energy disappear? And again, I guess 604 00:31:36,520 --> 00:31:38,960 Speaker 1: you can talk about taking it away at the beginning 605 00:31:39,000 --> 00:31:41,600 Speaker 1: of the universe and today, So what would happen if 606 00:31:41,640 --> 00:31:44,560 Speaker 1: I took it out when the universe started. It's fascinating 607 00:31:44,600 --> 00:31:47,640 Speaker 1: because these two different components, dark matter and dark energy 608 00:31:48,080 --> 00:31:50,520 Speaker 1: sort of dominate the stage at different part of the 609 00:31:50,560 --> 00:31:53,400 Speaker 1: history of the universe, Like dark matter controls the structure 610 00:31:53,400 --> 00:31:56,400 Speaker 1: of the universe from very early days, whereas dark energy 611 00:31:56,840 --> 00:31:59,920 Speaker 1: really only takes over in the last few billion years, 612 00:32:00,520 --> 00:32:02,400 Speaker 1: and so they really play a different role here, which 613 00:32:02,400 --> 00:32:06,320 Speaker 1: is fast. Yeah. To understand this, we have to understand 614 00:32:06,320 --> 00:32:09,600 Speaker 1: a little bit about the history of the expansion of 615 00:32:09,640 --> 00:32:12,600 Speaker 1: the universe. So go all the way back to the 616 00:32:12,720 --> 00:32:16,280 Speaker 1: very beginning and the universe somehow is created. We don't 617 00:32:16,320 --> 00:32:19,280 Speaker 1: understand that at all. And then there's inflation when the 618 00:32:19,360 --> 00:32:21,840 Speaker 1: universe goes from very hot and very dense to suddenly 619 00:32:22,240 --> 00:32:25,960 Speaker 1: much larger, and again we don't really understand that at all. 620 00:32:26,240 --> 00:32:28,440 Speaker 1: But from that going forward, we think we have an 621 00:32:28,520 --> 00:32:32,120 Speaker 1: understanding of how the universe expands and how that expansion 622 00:32:32,160 --> 00:32:35,880 Speaker 1: accelerates or decelerates, and it's controlled by how much matter 623 00:32:36,240 --> 00:32:38,760 Speaker 1: and radiation there is, how much energy there is in 624 00:32:38,800 --> 00:32:41,560 Speaker 1: the universe, and also in this dark energy, and the 625 00:32:41,560 --> 00:32:44,520 Speaker 1: two forces are usually working at odds with each other, 626 00:32:44,880 --> 00:32:47,920 Speaker 1: which so dark energy wasn't very instrumental in the Big Bang, 627 00:32:48,000 --> 00:32:50,640 Speaker 1: like it was an inflation sort of partly due to 628 00:32:50,680 --> 00:32:53,680 Speaker 1: dark energy, So we don't know. Inflation has a very 629 00:32:53,680 --> 00:32:56,440 Speaker 1: similar effect to dark energy, and that expands the universe 630 00:32:56,560 --> 00:32:59,200 Speaker 1: very rapidly, But we don't know if the mechanism of 631 00:32:59,240 --> 00:33:02,280 Speaker 1: inflation is the same as the mechanism of dark energy, 632 00:33:02,360 --> 00:33:04,880 Speaker 1: Like they both have the same effect, but we don't 633 00:33:04,920 --> 00:33:07,120 Speaker 1: know if they're the same thing. They could be, and 634 00:33:07,160 --> 00:33:09,960 Speaker 1: in some theories they are. In some theories they're totally different, 635 00:33:10,000 --> 00:33:12,360 Speaker 1: but we're really just at the very beginning stages of 636 00:33:12,480 --> 00:33:15,680 Speaker 1: understanding these things at all, and so we can't really 637 00:33:15,680 --> 00:33:17,880 Speaker 1: say that inflation is the same as dark energy. So 638 00:33:17,960 --> 00:33:21,880 Speaker 1: let's put inflation aside and think about what happens post inflation, 639 00:33:22,080 --> 00:33:24,960 Speaker 1: right basically after the Big Bang, if there was no 640 00:33:25,040 --> 00:33:27,160 Speaker 1: dark energy, I see, all right, So that the universe 641 00:33:27,280 --> 00:33:33,160 Speaker 1: just exploded or expanded rapidly after inflation, and now everything's 642 00:33:33,240 --> 00:33:35,080 Speaker 1: kind of hanging out there. So what would happen if 643 00:33:35,120 --> 00:33:37,400 Speaker 1: I turned off dark energy? So really not very much 644 00:33:37,480 --> 00:33:40,640 Speaker 1: like in the early universe, dark energy plays almost no role. 645 00:33:41,040 --> 00:33:43,040 Speaker 1: And the reason is that things are still really very 646 00:33:43,080 --> 00:33:45,440 Speaker 1: hot and dense. They have a lot of radiation. In 647 00:33:45,440 --> 00:33:49,320 Speaker 1: the first thousand years of the universe. Mostly the universe 648 00:33:49,400 --> 00:33:52,520 Speaker 1: is just radiation. We're talking like photons, like crazy, bouncing 649 00:33:52,560 --> 00:33:56,000 Speaker 1: around everywhere for the first forty seven thousand years. And 650 00:33:56,080 --> 00:33:58,520 Speaker 1: it's a little counterintuitive, but what happened in the very 651 00:33:58,560 --> 00:34:01,400 Speaker 1: beginning of the universe is that you expansion of the universe, 652 00:34:01,440 --> 00:34:04,200 Speaker 1: even though it's mostly just filled with stuff, right, And 653 00:34:04,200 --> 00:34:08,959 Speaker 1: typically think of stuff causing gravity, which causes you know, contraction, 654 00:34:09,560 --> 00:34:11,840 Speaker 1: But the matter in the radiation and the universe actually 655 00:34:11,880 --> 00:34:16,200 Speaker 1: caused some expansion early on. It made the universe get bigger. Now, 656 00:34:16,239 --> 00:34:19,840 Speaker 1: the effect of dark energy is to accelerate that expansion, 657 00:34:19,880 --> 00:34:22,319 Speaker 1: is to make that expansion happen faster and faster and 658 00:34:22,320 --> 00:34:25,920 Speaker 1: faster gravity works the other way, it makes the expansion 659 00:34:25,920 --> 00:34:30,400 Speaker 1: happen slower. Are you saying that dark energy didn't play 660 00:34:30,440 --> 00:34:33,680 Speaker 1: a role, Like it wasn't important or it was just 661 00:34:33,800 --> 00:34:35,920 Speaker 1: turned down in the early moments of the universe. It 662 00:34:35,960 --> 00:34:38,680 Speaker 1: didn't really play a role at all. Dark energy gets 663 00:34:38,719 --> 00:34:41,719 Speaker 1: more important as the universe gets bigger because it has 664 00:34:41,800 --> 00:34:45,080 Speaker 1: one really weird property is that it doesn't get diluted. 665 00:34:45,560 --> 00:34:48,640 Speaker 1: Like every chunk of space has the same amount of 666 00:34:48,680 --> 00:34:51,399 Speaker 1: dark energy, and if you double the space, you make 667 00:34:51,440 --> 00:34:55,000 Speaker 1: space bigger, you get more dark energy, whereas with matter 668 00:34:55,200 --> 00:34:58,280 Speaker 1: and radiation, like if you double the size of space, 669 00:34:58,640 --> 00:35:00,920 Speaker 1: then the matter gets less dense because you have the 670 00:35:01,000 --> 00:35:04,440 Speaker 1: same amount of matter, Like you have two protons in 671 00:35:04,480 --> 00:35:07,120 Speaker 1: a cubic meter of space, and then you expand the 672 00:35:07,200 --> 00:35:09,600 Speaker 1: universe to be twice as big. Now you have two 673 00:35:09,600 --> 00:35:12,640 Speaker 1: protons in two cubic meters of space, so you have 674 00:35:13,040 --> 00:35:16,920 Speaker 1: less matter density. But dark energy just doubles when you 675 00:35:17,000 --> 00:35:20,080 Speaker 1: double the space. So as space gets bigger, dark energy 676 00:35:20,120 --> 00:35:22,960 Speaker 1: gets more and more important. So dark energy, you could 677 00:35:22,960 --> 00:35:25,080 Speaker 1: have deleted it from the very early universe, it would 678 00:35:25,080 --> 00:35:27,480 Speaker 1: have had no role. But as the universe gets bigger 679 00:35:27,480 --> 00:35:30,120 Speaker 1: and bigger, it starts to take over and become dominant. Right, 680 00:35:30,160 --> 00:35:31,880 Speaker 1: I guess it's kind of like if you took it 681 00:35:31,880 --> 00:35:34,240 Speaker 1: out before it grew, then it wouldn't make a difference. 682 00:35:34,280 --> 00:35:38,040 Speaker 1: But now, in as the universe grew, dark energy also grew, 683 00:35:38,320 --> 00:35:40,880 Speaker 1: and so it just became more consequence. That's right. And 684 00:35:40,960 --> 00:35:43,080 Speaker 1: so if you had deleted it from the early universe 685 00:35:43,120 --> 00:35:46,000 Speaker 1: and it never had happened, right, we never had dark energy, 686 00:35:46,320 --> 00:35:48,239 Speaker 1: then the history of the universe would be like, you 687 00:35:48,320 --> 00:35:50,560 Speaker 1: have the Big Bang, you have all this matter, you 688 00:35:50,600 --> 00:35:53,120 Speaker 1: have all this radiation. You still have expansion of the 689 00:35:53,200 --> 00:35:56,480 Speaker 1: universe in the very early universe. But then gravity is 690 00:35:56,520 --> 00:36:00,400 Speaker 1: taking over. It's slowing down that expansion. Eventually it's stops 691 00:36:00,440 --> 00:36:02,360 Speaker 1: the expansion and it turns things around. We have a 692 00:36:02,400 --> 00:36:05,719 Speaker 1: contraction and the universe reverses and comes back into a 693 00:36:05,760 --> 00:36:09,760 Speaker 1: big crunch. So dark energy is the reason we're still around. 694 00:36:09,960 --> 00:36:11,879 Speaker 1: While we're still around, is the reason why we haven't 695 00:36:11,880 --> 00:36:13,920 Speaker 1: had a big crunch. But you wouldn't have noticed it 696 00:36:13,920 --> 00:36:16,439 Speaker 1: in the very early universe because it didn't really take 697 00:36:16,520 --> 00:36:19,600 Speaker 1: over until a little bit later. So wait, so I 698 00:36:19,640 --> 00:36:22,040 Speaker 1: took out dark energy at the beginning, the universe would 699 00:36:22,040 --> 00:36:24,319 Speaker 1: have expanded. And are you saying that by now, like 700 00:36:24,400 --> 00:36:27,040 Speaker 1: fourteen years into it, we wouldn't be here, like the 701 00:36:27,120 --> 00:36:31,400 Speaker 1: universe would have crunched already. Absolutely. Yeah. Without dark energy 702 00:36:31,440 --> 00:36:33,960 Speaker 1: in the universe, gravity would have won. It would have 703 00:36:34,000 --> 00:36:36,400 Speaker 1: slowed down the expansion. It would have stopped and turned 704 00:36:36,440 --> 00:36:39,360 Speaker 1: it around and crunched us. We wouldn't have this universe 705 00:36:39,440 --> 00:36:42,720 Speaker 1: without dark energy, Like none of the starts would have formed, 706 00:36:42,800 --> 00:36:44,960 Speaker 1: or they would have been starting to form. But then 707 00:36:45,000 --> 00:36:47,719 Speaker 1: the universe would crunch. Because you still have dark matter, 708 00:36:47,800 --> 00:36:51,000 Speaker 1: you would have formed stars and galaxies. But then without 709 00:36:51,120 --> 00:36:54,160 Speaker 1: dark energy, all that gravity would have gone into a 710 00:36:54,239 --> 00:36:57,399 Speaker 1: runaway effect and collapse the universe back into a very 711 00:36:57,520 --> 00:37:01,120 Speaker 1: very dense state. Okay, so you took it out early. 712 00:37:01,239 --> 00:37:03,719 Speaker 1: What have you waited a little bit before taking out 713 00:37:03,800 --> 00:37:05,880 Speaker 1: dark energy? So there's a bit of a dial there, right. 714 00:37:05,920 --> 00:37:08,920 Speaker 1: If you take it out too early, the universe crunches. 715 00:37:09,200 --> 00:37:11,040 Speaker 1: If you leave it in a little bit longer, then 716 00:37:11,120 --> 00:37:14,520 Speaker 1: allows the universe to expand more, It fights gravity longer, 717 00:37:14,719 --> 00:37:17,359 Speaker 1: and it gives you a longer and longer window at 718 00:37:17,440 --> 00:37:21,160 Speaker 1: some point. If you turn off dark energy late enough, 719 00:37:21,200 --> 00:37:24,600 Speaker 1: it's too late, like gravity can no longer win Like 720 00:37:24,719 --> 00:37:27,640 Speaker 1: in our universe today with dark energy, we have the 721 00:37:27,680 --> 00:37:31,680 Speaker 1: acceleration of the universe happening right now, like space is expanding, 722 00:37:31,680 --> 00:37:34,879 Speaker 1: and it's expanding faster and faster. So, for example, if 723 00:37:34,880 --> 00:37:38,080 Speaker 1: he turns it off today, gravity could not pull the 724 00:37:38,160 --> 00:37:41,600 Speaker 1: universe back into a dot. It's already too late for gravity. 725 00:37:41,600 --> 00:37:44,560 Speaker 1: Really is, because if you take out dark energy, the 726 00:37:44,640 --> 00:37:48,840 Speaker 1: universe stops expanding. It's like it's fixed in size. Wouldn't 727 00:37:48,880 --> 00:37:52,040 Speaker 1: gravity eventually bring everything together? Yes, But if you take 728 00:37:52,040 --> 00:37:54,600 Speaker 1: out dark energy, you don't stop the expansion. You stop 729 00:37:54,680 --> 00:37:58,880 Speaker 1: the acceleration of the expansion. You stop adding to the velocity. 730 00:37:58,920 --> 00:38:02,080 Speaker 1: Things still have a velocity. Remember Newton's lass tell us 731 00:38:02,160 --> 00:38:05,320 Speaker 1: that things and motions stay in motion unless you apply 732 00:38:05,400 --> 00:38:07,879 Speaker 1: a force to them, and so dark energy is that force. 733 00:38:07,960 --> 00:38:10,640 Speaker 1: If you stop pushing on things, they're still flying out. 734 00:38:10,680 --> 00:38:14,000 Speaker 1: Their space is still expanding. And so dark energy is 735 00:38:14,000 --> 00:38:17,880 Speaker 1: the acceleration of the expansion, not the expansion itself. So 736 00:38:17,920 --> 00:38:20,960 Speaker 1: if you take out dark energy, you stop the acceleration, 737 00:38:21,400 --> 00:38:24,359 Speaker 1: but things are still expanding and gravity does not have 738 00:38:24,400 --> 00:38:26,600 Speaker 1: the power to turn that around. Wait, what what is 739 00:38:26,600 --> 00:38:30,360 Speaker 1: still expanding? Like the distance between stars and galaxies or 740 00:38:30,480 --> 00:38:34,560 Speaker 1: with space itself still be you know, multiplying and growing both. 741 00:38:34,680 --> 00:38:38,239 Speaker 1: We're talking about the expansion of space itself, right, and 742 00:38:38,280 --> 00:38:41,799 Speaker 1: that expansion is accelerated by dark energy. But you still 743 00:38:41,800 --> 00:38:44,520 Speaker 1: get expansion even without dark energy. Really, so if you 744 00:38:44,560 --> 00:38:47,319 Speaker 1: take out dark energy, space would still be growing. What 745 00:38:47,520 --> 00:38:49,879 Speaker 1: is making it grow? Don't you need energy for that? Well, 746 00:38:49,880 --> 00:38:53,720 Speaker 1: the expansion can continue without dark energy. But matter itself 747 00:38:53,800 --> 00:38:56,520 Speaker 1: causes the expansion of the universe, like we were talking 748 00:38:56,520 --> 00:38:59,600 Speaker 1: about earlier in the very early university was just matter 749 00:39:00,200 --> 00:39:04,560 Speaker 1: causes the universe to expand. Gravity gives you a negative 750 00:39:04,800 --> 00:39:08,080 Speaker 1: derivative on that expansion. It slows down that expansion, and 751 00:39:08,200 --> 00:39:11,759 Speaker 1: dark energy increases that expansion. So sort of two things 752 00:39:11,800 --> 00:39:15,080 Speaker 1: to talk about there, like the velocity of space and 753 00:39:15,200 --> 00:39:20,640 Speaker 1: its acceleration. So matter gives space velocity to expand outwards, 754 00:39:20,960 --> 00:39:24,920 Speaker 1: gravity gives you a negative acceleration on that, and dark 755 00:39:25,040 --> 00:39:27,360 Speaker 1: energy gives you positive accelerat Dark energy is kind of 756 00:39:27,360 --> 00:39:30,279 Speaker 1: like the booster rocket or like the turbo yeah, and 757 00:39:30,360 --> 00:39:33,520 Speaker 1: the universe. Yeah, So if you take away dark energy 758 00:39:33,520 --> 00:39:35,880 Speaker 1: in the very very early universe, so it never happened, 759 00:39:36,120 --> 00:39:38,680 Speaker 1: then gravity would win and things would crunch. If you 760 00:39:38,719 --> 00:39:41,560 Speaker 1: take it away today, right then it's sort of too late. 761 00:39:41,560 --> 00:39:44,800 Speaker 1: He's already won the game. And gravity can't turn things around, 762 00:39:45,160 --> 00:39:47,279 Speaker 1: like things are moving out too fast and too far 763 00:39:47,320 --> 00:39:49,640 Speaker 1: away for things to turn around. And there's like a 764 00:39:49,719 --> 00:39:52,600 Speaker 1: middle time there where if you deleted dark energy just 765 00:39:52,800 --> 00:39:55,600 Speaker 1: the right moment, you would find like a balance there. 766 00:39:55,840 --> 00:39:58,080 Speaker 1: And there's some moment there there's a tipping point, and 767 00:39:58,080 --> 00:40:00,439 Speaker 1: I'm not sure you could actually walk that and stay 768 00:40:00,480 --> 00:40:03,240 Speaker 1: on that tipping point, but there's some point at which 769 00:40:03,320 --> 00:40:06,440 Speaker 1: if you don't delete dark energy before that moment, it's 770 00:40:06,440 --> 00:40:09,080 Speaker 1: gonna win. So I guess you're saying that dark energy 771 00:40:09,120 --> 00:40:12,399 Speaker 1: could retire right now. It's done its job, it's put 772 00:40:12,400 --> 00:40:15,800 Speaker 1: in its time, and now the universe will never crunch 773 00:40:15,880 --> 00:40:19,440 Speaker 1: back down into right, I mean without even if you 774 00:40:19,480 --> 00:40:21,920 Speaker 1: took out dark energy, that the universe will never crunch 775 00:40:22,160 --> 00:40:25,080 Speaker 1: back down into an inverse big bang. That's right. To 776 00:40:25,120 --> 00:40:27,840 Speaker 1: make an inverse big bang, now you need dark energy 777 00:40:27,880 --> 00:40:31,000 Speaker 1: to reverse, not just to disappear. You needed to turn 778 00:40:31,040 --> 00:40:34,960 Speaker 1: around and somehow cause the contraction of the universe. And 779 00:40:35,000 --> 00:40:37,200 Speaker 1: you might think, well, but it's only ever caused the 780 00:40:37,239 --> 00:40:40,839 Speaker 1: expansion of the universe. Why would it cause contraction, which 781 00:40:40,880 --> 00:40:43,080 Speaker 1: is a great question. But remember that we don't know 782 00:40:43,120 --> 00:40:45,960 Speaker 1: anything about dark energy. We have speculations that it might 783 00:40:46,000 --> 00:40:48,920 Speaker 1: be the cosmological constant or something else, so the energy 784 00:40:48,960 --> 00:40:51,920 Speaker 1: of empty space, but we really have no understanding of 785 00:40:51,960 --> 00:40:54,560 Speaker 1: what it is, which means we can't predict its future. 786 00:40:54,600 --> 00:40:57,920 Speaker 1: And it could do something bonkers like turn around and 787 00:40:58,160 --> 00:41:01,239 Speaker 1: change direction and cause the contract of the universe, like 788 00:41:01,320 --> 00:41:04,680 Speaker 1: it could start taking energy away from space almost and 789 00:41:04,800 --> 00:41:07,040 Speaker 1: we don't understand it, so we can't predict its future. 790 00:41:07,480 --> 00:41:11,080 Speaker 1: If dark energy disappeared today, then yes, there's already enough 791 00:41:11,120 --> 00:41:13,759 Speaker 1: expansion that gravity can't win. And if you kept dark 792 00:41:13,840 --> 00:41:16,480 Speaker 1: energy doing what it's doing, which is causing the acceleration, 793 00:41:16,719 --> 00:41:19,640 Speaker 1: then you know it's already game over. And we're accelerating 794 00:41:19,680 --> 00:41:23,799 Speaker 1: towards having more and more distance between galaxies, having these 795 00:41:23,840 --> 00:41:26,759 Speaker 1: little blobs of stuff being more and more separated and 796 00:41:26,800 --> 00:41:29,840 Speaker 1: more and more isolated, and each one gravity is strong 797 00:41:29,960 --> 00:41:32,040 Speaker 1: enough to hold together. Right, dark energy is not going 798 00:41:32,080 --> 00:41:34,480 Speaker 1: to rip you from the Earth or rip the Solar 799 00:41:34,520 --> 00:41:37,680 Speaker 1: System apart, because gravity has won these little micro battles 800 00:41:37,800 --> 00:41:41,480 Speaker 1: to hold these little structures together. More likely will collapse 801 00:41:41,520 --> 00:41:44,440 Speaker 1: into a bunch of black holes than separated with vast 802 00:41:44,480 --> 00:41:50,959 Speaker 1: distances between other black holes. Not a happy outlook black 803 00:41:50,960 --> 00:41:56,520 Speaker 1: holes to the end of time. White's you have a 804 00:41:56,680 --> 00:42:04,200 Speaker 1: dark choice here of people between lightness and dark that's right, 805 00:42:04,560 --> 00:42:07,320 Speaker 1: reality or fantasy. All right, Well, I'm getting the sense 806 00:42:07,360 --> 00:42:11,080 Speaker 1: of that dark energy and dark matter were super important 807 00:42:11,200 --> 00:42:13,880 Speaker 1: for us to be here. We needed them to get 808 00:42:13,920 --> 00:42:15,640 Speaker 1: to where we are. But now that the universe is 809 00:42:15,680 --> 00:42:18,479 Speaker 1: kind of chugging along, we really don't kind of need 810 00:42:18,520 --> 00:42:20,920 Speaker 1: either of them right now. Well, that's true, Like you 811 00:42:20,920 --> 00:42:24,120 Speaker 1: could turn them off now and the humanity would probably 812 00:42:24,160 --> 00:42:26,719 Speaker 1: go on the same trajectory as it would have been. Yeah, well, 813 00:42:26,719 --> 00:42:29,000 Speaker 1: you know that's not very grateful. You know, it's just like, 814 00:42:29,200 --> 00:42:30,919 Speaker 1: what can I remove from my life that I don't 815 00:42:30,920 --> 00:42:33,880 Speaker 1: need anymore now that I've made it. That's a very 816 00:42:33,920 --> 00:42:36,640 Speaker 1: generous attitude. We should remember how we got here and 817 00:42:36,680 --> 00:42:40,640 Speaker 1: all the little people necessary along the way. But you know, 818 00:42:40,680 --> 00:42:42,840 Speaker 1: as Mary consas is, you know, think about it and 819 00:42:43,000 --> 00:42:45,440 Speaker 1: does it brings you joy? Daniel, And if not, just 820 00:42:45,480 --> 00:42:48,839 Speaker 1: throw it out. Dark matter brings me joy. But you're right, 821 00:42:49,120 --> 00:42:51,279 Speaker 1: we don't need it. We could delete dark matter from 822 00:42:51,320 --> 00:42:54,200 Speaker 1: our universe and our solar system would be fine. We 823 00:42:54,239 --> 00:42:57,320 Speaker 1: can delete dark energy from our universe, and it wouldn't 824 00:42:57,320 --> 00:43:00,759 Speaker 1: really change the fate of our solar system all. So 825 00:43:00,840 --> 00:43:03,560 Speaker 1: you're right, there were instrumental in getting us here, but 826 00:43:03,600 --> 00:43:06,000 Speaker 1: we could cut them out of our enter. I guess. 827 00:43:06,080 --> 00:43:07,719 Speaker 1: I mean like in a way almost like if you 828 00:43:07,719 --> 00:43:10,120 Speaker 1: get rid of dark energy, it almost makes the universe 829 00:43:10,160 --> 00:43:13,760 Speaker 1: more accessible, right, because if things aren't accelerating further apart, 830 00:43:14,080 --> 00:43:17,640 Speaker 1: then it increases our chances of you know, reaching other 831 00:43:17,719 --> 00:43:20,640 Speaker 1: places in the universe. Yeah, that's true. It's a bit 832 00:43:20,640 --> 00:43:23,120 Speaker 1: of a grim picture to imagine that dark energy could 833 00:43:23,160 --> 00:43:27,479 Speaker 1: be creating these vast distances between superclusters of galaxies, making 834 00:43:27,520 --> 00:43:31,120 Speaker 1: it literally impossible to explore the universe. And so yeah, 835 00:43:31,320 --> 00:43:33,400 Speaker 1: I would actually like to turn off dark energy or 836 00:43:33,440 --> 00:43:35,200 Speaker 1: reverse it a little bit, bring some of that stuff 837 00:43:35,200 --> 00:43:37,360 Speaker 1: a little closer. We have our human rocket engines a 838 00:43:37,440 --> 00:43:39,520 Speaker 1: chance to explore that. You mean you would like me 839 00:43:39,560 --> 00:43:42,160 Speaker 1: to go into the control room and fiddle with the knob, 840 00:43:43,040 --> 00:43:49,719 Speaker 1: be like off on off sufficient adult supervision. Yes, so 841 00:43:49,760 --> 00:43:52,400 Speaker 1: I'd be like flipping the switch and then just so 842 00:43:52,520 --> 00:43:54,480 Speaker 1: that the eighties are close enough for you to say 843 00:43:54,560 --> 00:43:57,080 Speaker 1: hi to them, and then switching it back on. That 844 00:43:57,120 --> 00:43:59,759 Speaker 1: sounds great, Yeah, do that all right, let me, let 845 00:43:59,760 --> 00:44:04,640 Speaker 1: me put on my infinity glossier and uh twiddle my thumbs. 846 00:44:04,920 --> 00:44:07,680 Speaker 1: All right. Well, it sounds like these are a really 847 00:44:07,920 --> 00:44:11,000 Speaker 1: super fun thought experiments, but I feel like they're also 848 00:44:11,080 --> 00:44:15,240 Speaker 1: a big part of how you know that these things exist, meaning, 849 00:44:15,280 --> 00:44:17,759 Speaker 1: like you know, you play these experiments in your head, 850 00:44:17,800 --> 00:44:20,520 Speaker 1: like what if dark matter never existed, Well, the universe 851 00:44:20,520 --> 00:44:22,319 Speaker 1: wouldn't be the way it is, which sort of tells 852 00:44:22,360 --> 00:44:25,560 Speaker 1: you that dark matter does exist. Yeah, exactly. And it's 853 00:44:25,600 --> 00:44:28,799 Speaker 1: not just these large scale structures the organization and the 854 00:44:28,880 --> 00:44:31,560 Speaker 1: size the universe. There are a lot of other details 855 00:44:31,560 --> 00:44:34,000 Speaker 1: that tell us how much dark matter there is, how 856 00:44:34,080 --> 00:44:37,200 Speaker 1: much dark energy there is, how they interact, and that 857 00:44:37,320 --> 00:44:40,160 Speaker 1: come from lots of different observations, you know, from looking 858 00:44:40,160 --> 00:44:42,399 Speaker 1: at the early light of the universe at all sorts 859 00:44:42,440 --> 00:44:45,440 Speaker 1: of other crazy detailed measurements. So it really seems like 860 00:44:45,520 --> 00:44:47,560 Speaker 1: dark matter and dark energy are a thing and that 861 00:44:47,640 --> 00:44:50,520 Speaker 1: they are necessary things to make the universe the way 862 00:44:50,560 --> 00:44:52,920 Speaker 1: it is. And of course the next question is like 863 00:44:53,400 --> 00:44:56,319 Speaker 1: why are they at those values? Could there have been 864 00:44:56,719 --> 00:45:00,120 Speaker 1: more dark matter or more dark energy? Why these numbers 865 00:45:00,160 --> 00:45:02,400 Speaker 1: and not other number? Right, But we almost kind of 866 00:45:02,400 --> 00:45:04,760 Speaker 1: don't want to ask those questions, because then we wouldn't 867 00:45:04,760 --> 00:45:08,200 Speaker 1: be here. I want to ask those questions because I 868 00:45:08,239 --> 00:45:11,200 Speaker 1: want to know is it an accident that we're here? 869 00:45:11,360 --> 00:45:15,120 Speaker 1: Or are we inevitable as the only possible universe one 870 00:45:15,160 --> 00:45:17,360 Speaker 1: that has this kind of structure, or are we totally 871 00:45:17,440 --> 00:45:20,200 Speaker 1: lucky one in a trillion chance. To me, those are 872 00:45:20,239 --> 00:45:22,680 Speaker 1: the deepest questions of physics. Those are the reasons I 873 00:45:22,719 --> 00:45:25,560 Speaker 1: got into physics, is to try to answer these massive 874 00:45:25,640 --> 00:45:29,520 Speaker 1: philosophical questions about the context of our very lives. Right, yeah, See, 875 00:45:29,560 --> 00:45:32,680 Speaker 1: it's not just Sanna's who's inevitable or wants to be inevitable, 876 00:45:34,320 --> 00:45:39,000 Speaker 1: it's Daniel. It's questions. Really, it's wondering about the universe 877 00:45:39,120 --> 00:45:42,839 Speaker 1: that's ineviable. All right, Well, I think we've reached the 878 00:45:42,960 --> 00:45:46,680 Speaker 1: endgame here of our episode. We hope that you look 879 00:45:46,719 --> 00:45:49,600 Speaker 1: out into the universe tonight or tomorrow or the next 880 00:45:49,680 --> 00:45:51,600 Speaker 1: day and think about what are some of the things 881 00:45:51,640 --> 00:45:54,439 Speaker 1: that led to us being here, and how important they are, 882 00:45:54,480 --> 00:45:57,319 Speaker 1: and what would happen if things were totally different, and 883 00:45:57,360 --> 00:46:00,440 Speaker 1: share with us you're wondering in your thoughts and your questions. 884 00:46:00,480 --> 00:46:03,520 Speaker 1: Please write to us two questions at Daniel and Jorge 885 00:46:03,520 --> 00:46:06,760 Speaker 1: dot com or interact with us on Twitter at Daniel 886 00:46:06,800 --> 00:46:10,000 Speaker 1: and Jorge, where we make bad jokes and answer questions. 887 00:46:10,160 --> 00:46:20,960 Speaker 1: Thanks for joining us, see you next time. Thanks for listening, 888 00:46:21,000 --> 00:46:23,719 Speaker 1: and remember that Daniel and Jorge Explain the Universe is 889 00:46:23,760 --> 00:46:27,239 Speaker 1: a production of I Heart Radio. For more podcast from 890 00:46:27,280 --> 00:46:31,000 Speaker 1: my heart Radio, visit the i heart Radio app, Apple Podcasts, 891 00:46:31,160 --> 00:46:39,160 Speaker 1: or wherever you listen to your favorite shows. Yea