1 00:00:08,720 --> 00:00:10,559 Speaker 1: Hey, Daniel, do you think there are some questions out 2 00:00:10,600 --> 00:00:14,440 Speaker 1: there that will never know the answer to? Deep questions 3 00:00:14,480 --> 00:00:17,200 Speaker 1: like when is the best time to eat a banana? 4 00:00:18,120 --> 00:00:20,919 Speaker 1: What do you mean is there a controversy about that? Oh? Man, 5 00:00:20,960 --> 00:00:24,160 Speaker 1: people argue about this stuff online, you know, slightly green 6 00:00:24,360 --> 00:00:28,080 Speaker 1: or wait for the brown spots. There's a lot of debate. Yeah. Well, 7 00:00:28,240 --> 00:00:32,760 Speaker 1: I don't discriminate. I think every banana is delicious. But 8 00:00:33,040 --> 00:00:35,200 Speaker 1: I was thinking, you know, a bigger questions, bigger questions 9 00:00:35,200 --> 00:00:38,000 Speaker 1: about the universe, like are we alone? Are there aliens 10 00:00:38,040 --> 00:00:40,400 Speaker 1: out there? You just went right for the alien button. 11 00:00:41,240 --> 00:00:43,080 Speaker 1: I have it right here on my desk for a reason. 12 00:00:44,640 --> 00:00:47,839 Speaker 1: But yeah, yeah, I'm talking about huge mind blowing questions, 13 00:00:47,880 --> 00:00:51,720 Speaker 1: you know, like is like are we alone in the universe? 14 00:00:52,240 --> 00:00:55,360 Speaker 1: You know, is humanity destined to wonder these questions about 15 00:00:55,360 --> 00:00:58,800 Speaker 1: these questions forever? Or do you think we'll find answers eventually? 16 00:00:59,000 --> 00:01:01,000 Speaker 1: I think as long as we were around and we're 17 00:01:01,040 --> 00:01:04,240 Speaker 1: putting some money in basic research, we'll keep making progress. 18 00:01:04,280 --> 00:01:06,240 Speaker 1: So you know, it could take a hundred years, it 19 00:01:06,280 --> 00:01:09,199 Speaker 1: could take a thousand years, but I think some days 20 00:01:09,280 --> 00:01:11,600 Speaker 1: someone will come along with a clever way to give 21 00:01:11,680 --> 00:01:15,000 Speaker 1: us an answer. Even for the very biggest questions, like 22 00:01:15,160 --> 00:01:18,920 Speaker 1: when do aliens like to eat their bananas? I think 23 00:01:18,920 --> 00:01:21,360 Speaker 1: aliens like to eat you while you eat a banana. 24 00:01:21,600 --> 00:01:23,759 Speaker 1: I got dark. I got a bunch of dark spots 25 00:01:23,760 --> 00:01:42,520 Speaker 1: all of a sudden. Hi am Jorge. I'm a cartoonist 26 00:01:42,640 --> 00:01:45,920 Speaker 1: and the creator of PhD comics. I'm Daniel. I'm a 27 00:01:45,920 --> 00:01:49,680 Speaker 1: particle physicist, and I love really big questions we might 28 00:01:49,960 --> 00:01:52,240 Speaker 1: never know the answer to. And where do you fall 29 00:01:52,440 --> 00:01:56,840 Speaker 1: Daniel on the bananas, Kale, green or spotty? I think 30 00:01:57,120 --> 00:01:59,520 Speaker 1: right in between. Green makes you just your mouth feel 31 00:01:59,520 --> 00:02:02,920 Speaker 1: like you're eating cardboard, but too spotty, and you're basically 32 00:02:02,920 --> 00:02:05,680 Speaker 1: eating a smoothie, which is not something you want. That's 33 00:02:05,680 --> 00:02:08,280 Speaker 1: why they invented smoothies. That's right. I actually like the 34 00:02:08,320 --> 00:02:11,440 Speaker 1: red bananas. If you had the red bananas, I think 35 00:02:11,520 --> 00:02:14,040 Speaker 1: I have. Yeah. They have them in Asia, right, yeah, 36 00:02:14,080 --> 00:02:18,200 Speaker 1: and also in Central America. Slightly strawberry flavored, quite delicious. 37 00:02:18,280 --> 00:02:23,160 Speaker 1: It's got a bouquet of strawberry and oak carbon. They 38 00:02:23,200 --> 00:02:30,040 Speaker 1: are sassy but unpretentious. Here we are La. Here we 39 00:02:30,080 --> 00:02:32,720 Speaker 1: are shilling for Big Banana. But welcome to our podcast. 40 00:02:32,840 --> 00:02:37,080 Speaker 1: Daniel and Jorge explain the universe and apparently bananas, in 41 00:02:37,120 --> 00:02:40,040 Speaker 1: which we like to explore topics that are big, bigger 42 00:02:40,080 --> 00:02:44,120 Speaker 1: even than questions about bananas, questions so big you can't 43 00:02:44,120 --> 00:02:46,600 Speaker 1: even wrap your mind around them. Yeah, it's our show 44 00:02:46,919 --> 00:02:49,680 Speaker 1: produced by our Hard Radio, in which we think about 45 00:02:49,800 --> 00:02:52,720 Speaker 1: some of the biggest questions that they're that can be 46 00:02:52,760 --> 00:02:56,480 Speaker 1: asked about this crazy and pretty large universe we live in, 47 00:02:56,720 --> 00:02:58,280 Speaker 1: that's right, and we like to take you to the 48 00:02:58,360 --> 00:03:01,520 Speaker 1: forefront of knowledge, what scientists are thinking about, what the 49 00:03:01,600 --> 00:03:04,639 Speaker 1: experts in the world have in their minds, but then 50 00:03:04,720 --> 00:03:08,240 Speaker 1: translated so that you out there with your kids or 51 00:03:08,280 --> 00:03:11,640 Speaker 1: listening on your commute or everybody who loves questions and 52 00:03:11,680 --> 00:03:14,040 Speaker 1: wants to understand the universe can really dig into it 53 00:03:14,200 --> 00:03:16,920 Speaker 1: and get something out of it more than just banana jokes. 54 00:03:17,160 --> 00:03:18,360 Speaker 1: Part of our what you have to do is not 55 00:03:18,440 --> 00:03:21,600 Speaker 1: just talk about questions for which physicists know the answer 56 00:03:21,639 --> 00:03:23,519 Speaker 1: and try to explain to you those answers, but we 57 00:03:23,560 --> 00:03:26,200 Speaker 1: also kind of like to talk about the open questions 58 00:03:26,200 --> 00:03:29,160 Speaker 1: out there, the questions that not even people with PhD 59 00:03:29,240 --> 00:03:32,600 Speaker 1: s and universities have a good answer for. Are you 60 00:03:32,600 --> 00:03:35,360 Speaker 1: saying PhDs don't give you all the answers? I wish 61 00:03:35,400 --> 00:03:37,720 Speaker 1: I had an answer for that, Danny. I remember getting 62 00:03:37,720 --> 00:03:40,320 Speaker 1: my PhD. It was very unceremonious moment. Did you get 63 00:03:40,360 --> 00:03:44,080 Speaker 1: it by default? Is that what you're saying? No? At Berkeley, 64 00:03:44,160 --> 00:03:46,240 Speaker 1: when you turn in your PhD, you're in some sub 65 00:03:46,320 --> 00:03:48,560 Speaker 1: sub basement and you give it to the margins lady 66 00:03:48,840 --> 00:03:52,040 Speaker 1: and she measures the margins and your PhD, and if 67 00:03:52,040 --> 00:03:54,600 Speaker 1: everything looks ship shape, she gives you a lollipop that 68 00:03:54,680 --> 00:03:58,480 Speaker 1: says PhD on it. And that's the moment you have 69 00:03:58,520 --> 00:04:02,680 Speaker 1: a PhD? Uh? Did they? Um? Did you do? You 70 00:04:02,680 --> 00:04:05,320 Speaker 1: still have that lollipop? You know, we recently cleaned out 71 00:04:05,360 --> 00:04:07,640 Speaker 1: our house and I found a lollipop and my daughter Hayes, 72 00:04:07,640 --> 00:04:10,320 Speaker 1: I was like, why does this lollipop say PhD on it? 73 00:04:10,760 --> 00:04:13,800 Speaker 1: You found it? You still head it around, lapping around? 74 00:04:14,080 --> 00:04:15,920 Speaker 1: And did you let your daughter eat it? Because it's 75 00:04:15,960 --> 00:04:18,880 Speaker 1: probably like twenty years old? Man, I said, eat that 76 00:04:19,160 --> 00:04:21,240 Speaker 1: and you will learn all the secrets of the universe. 77 00:04:21,800 --> 00:04:25,920 Speaker 1: It's the red deal. Take the red lollipop and you 78 00:04:25,960 --> 00:04:28,599 Speaker 1: will never go back. No, but it's not very satisfied. 79 00:04:28,680 --> 00:04:30,200 Speaker 1: You know, that moment you get a PhD, you don't 80 00:04:30,200 --> 00:04:32,400 Speaker 1: feel like you know that much more. It's like a 81 00:04:32,480 --> 00:04:36,320 Speaker 1: slow accumulation of knowledge and understanding, and in some ways 82 00:04:36,400 --> 00:04:39,320 Speaker 1: you learn how little you know about the universe. Right, 83 00:04:39,360 --> 00:04:43,120 Speaker 1: You're like grappling with the infinity of our of our ignorance. Yeah, 84 00:04:43,160 --> 00:04:45,720 Speaker 1: I mean, at some point you basically become the world's 85 00:04:45,800 --> 00:04:49,880 Speaker 1: expert in a very particular topic, and you realize that 86 00:04:49,920 --> 00:04:53,800 Speaker 1: if you don't know, nobody knows. Like robots that run 87 00:04:53,800 --> 00:04:56,520 Speaker 1: like cockroaches, for example, Yeah, that's right, nobody knows how 88 00:04:56,560 --> 00:04:59,080 Speaker 1: to make them practical. Nobody knows. If I don't know 89 00:04:59,120 --> 00:05:02,920 Speaker 1: how to make them practical, nobody knows, that's right. And 90 00:05:02,960 --> 00:05:06,080 Speaker 1: one of the funnest questions, one of the really crazy 91 00:05:06,160 --> 00:05:08,679 Speaker 1: things to think about, is just sort of the nature 92 00:05:08,760 --> 00:05:12,000 Speaker 1: of the universe we find ourselves in. Yeah, what what 93 00:05:12,160 --> 00:05:14,680 Speaker 1: is it like really? I mean from we we know 94 00:05:14,720 --> 00:05:17,120 Speaker 1: what we can see from this little point in the universe, 95 00:05:17,120 --> 00:05:19,040 Speaker 1: in the in the milky Way, from this little rock 96 00:05:19,120 --> 00:05:22,680 Speaker 1: that we're all floating on, but and we can see 97 00:05:22,680 --> 00:05:24,680 Speaker 1: some stuff out there. But what is the universe really 98 00:05:24,760 --> 00:05:26,920 Speaker 1: like out there? You know, what's the shape of it? 99 00:05:27,160 --> 00:05:30,440 Speaker 1: How how far does it go? And and what's out there? 100 00:05:30,600 --> 00:05:34,000 Speaker 1: And it's fascinating to me that this is a fascinating question, 101 00:05:34,600 --> 00:05:37,359 Speaker 1: you know, like it's fascinating that it's fascinating. Yeah, that 102 00:05:37,440 --> 00:05:40,359 Speaker 1: it's one of the questions that people want answers to 103 00:05:40,440 --> 00:05:43,599 Speaker 1: that people want to know this about the universe. You know, 104 00:05:43,600 --> 00:05:45,600 Speaker 1: people have all sorts of questions about how stars are 105 00:05:45,600 --> 00:05:48,279 Speaker 1: formed and how planets are made, and whether they're aliens 106 00:05:48,279 --> 00:05:50,640 Speaker 1: out there, but people are also just curious about like 107 00:05:51,040 --> 00:05:54,240 Speaker 1: how far does it go? How does that all work? 108 00:05:54,279 --> 00:05:56,320 Speaker 1: And to me, that says something about you know, what 109 00:05:56,360 --> 00:05:58,280 Speaker 1: we want to know the answers to tells me something 110 00:05:58,320 --> 00:06:01,000 Speaker 1: about who we are and how we think. Do you 111 00:06:01,000 --> 00:06:04,640 Speaker 1: think this question of um, what the universe is like 112 00:06:04,720 --> 00:06:07,960 Speaker 1: out there is kind of primal to us as human beings, 113 00:06:07,960 --> 00:06:11,039 Speaker 1: Like there's something innate in our nature that really kind 114 00:06:11,040 --> 00:06:13,640 Speaker 1: of wants to know kind of what what is this 115 00:06:13,680 --> 00:06:15,960 Speaker 1: thing that we live in? Yeah, we want to understand ourselves. 116 00:06:16,000 --> 00:06:18,680 Speaker 1: We also really want to understand our context. You know, 117 00:06:19,320 --> 00:06:21,440 Speaker 1: like if you're born in a little village, you wonder 118 00:06:21,839 --> 00:06:24,160 Speaker 1: what else is out there beyond the edge of the village, 119 00:06:24,760 --> 00:06:27,200 Speaker 1: And if you're an explorer, you wonder like what's deep 120 00:06:27,240 --> 00:06:29,560 Speaker 1: in that jungle and what's out beyond the oceans, And 121 00:06:29,560 --> 00:06:31,680 Speaker 1: it's just something in humanity that wants to know, like 122 00:06:31,960 --> 00:06:35,440 Speaker 1: what is the nature of their context? What defines our existence? 123 00:06:35,480 --> 00:06:38,560 Speaker 1: What's beyond these four walls? Yeah, you can imagine being 124 00:06:38,600 --> 00:06:41,039 Speaker 1: like an early explorer and thinking, you know, is this 125 00:06:41,120 --> 00:06:43,760 Speaker 1: the only continent or are there more continent or there 126 00:06:43,800 --> 00:06:46,040 Speaker 1: three continents out there if I keep going, or are 127 00:06:46,040 --> 00:06:49,440 Speaker 1: there an infinite number of continents? Yeah? And I love 128 00:06:49,480 --> 00:06:51,680 Speaker 1: some of these sort of ancient arguments, you know, from 129 00:06:51,720 --> 00:06:54,440 Speaker 1: like the Greeks and those folks, about like how big 130 00:06:54,680 --> 00:06:57,400 Speaker 1: is space and how far does it go? And it 131 00:06:57,480 --> 00:07:00,240 Speaker 1: really reveals something about the way they thought. To the 132 00:07:00,320 --> 00:07:02,360 Speaker 1: on the podcast, we'll be tackling one of these big 133 00:07:02,680 --> 00:07:06,240 Speaker 1: questions about the universe, probably maybe the biggest question you 134 00:07:06,279 --> 00:07:10,400 Speaker 1: can ask about the universe, so to the on the podcast, 135 00:07:10,400 --> 00:07:19,040 Speaker 1: we'll be asking the question, is the universe infinite or 136 00:07:19,240 --> 00:07:24,160 Speaker 1: is it just mind modeling lee enormous, right, but enormous 137 00:07:24,200 --> 00:07:27,840 Speaker 1: but with a limit like finite finite? Right? Does it 138 00:07:27,920 --> 00:07:32,480 Speaker 1: have a size or does it go on literally forever 139 00:07:33,080 --> 00:07:36,440 Speaker 1: and ever? Yeah, it's totally a fascinating question. And I 140 00:07:36,480 --> 00:07:39,320 Speaker 1: was reading about this and I came across the sort 141 00:07:39,320 --> 00:07:42,480 Speaker 1: of ancient argument for the universe being infinite some of 142 00:07:42,480 --> 00:07:45,320 Speaker 1: the ancient Greeks. They believe the argument was infinite and 143 00:07:45,360 --> 00:07:49,960 Speaker 1: they just needed a javelin to prove their point. Really, Wow, 144 00:07:50,160 --> 00:07:52,320 Speaker 1: all this time, you guys have been building telescopes and 145 00:07:52,400 --> 00:07:55,600 Speaker 1: space telescopes and particle colliders. All you needed was a 146 00:07:55,680 --> 00:07:59,320 Speaker 1: stick exactly. I like the low tech solution to some 147 00:07:59,360 --> 00:08:02,920 Speaker 1: of these questions. Wait, so you're saying the Greeks wondering 148 00:08:03,000 --> 00:08:05,480 Speaker 1: that the universe was infinite. So they knew kind of 149 00:08:05,560 --> 00:08:07,640 Speaker 1: generally what was going on, like we're a planet, we're 150 00:08:07,640 --> 00:08:10,040 Speaker 1: in a solar system, and then they were they're just 151 00:08:10,080 --> 00:08:12,520 Speaker 1: wondering if the Earth was infinite. No, they knew that, 152 00:08:12,560 --> 00:08:14,800 Speaker 1: you know, there were planets. In fact, the Babylonians knew 153 00:08:14,800 --> 00:08:17,360 Speaker 1: that there were other planets out there in the sky. 154 00:08:17,440 --> 00:08:19,720 Speaker 1: We didn't know the nature of space or you know 155 00:08:19,760 --> 00:08:21,880 Speaker 1: that the Sun was just an example of other stars. 156 00:08:21,920 --> 00:08:24,080 Speaker 1: But they had the sense that, you know, the sky 157 00:08:24,240 --> 00:08:26,360 Speaker 1: wasn't a ceiling. The things went on for a while 158 00:08:26,400 --> 00:08:29,560 Speaker 1: and the question was how far do they go? So 159 00:08:29,960 --> 00:08:32,960 Speaker 1: how tall is the ceiling in this bio dome we 160 00:08:33,040 --> 00:08:35,840 Speaker 1: live in. Yeah, and they had this fun sort of 161 00:08:35,840 --> 00:08:38,400 Speaker 1: thought experiment because they couldn't venture out into space and 162 00:08:38,440 --> 00:08:42,280 Speaker 1: involved throwing a javelin, And the argument goes something like this, like, 163 00:08:42,720 --> 00:08:46,920 Speaker 1: imagine the universe is finite. Okay, like it has an 164 00:08:46,960 --> 00:08:49,160 Speaker 1: edge to it has an edge to it. Now go 165 00:08:49,240 --> 00:08:53,640 Speaker 1: to that edge and throw a javelin. What happens Either 166 00:08:54,320 --> 00:08:57,520 Speaker 1: the javelin keep going, in which case you're not actually 167 00:08:57,520 --> 00:09:01,760 Speaker 1: at the edge right and repeat forever, or the javelin 168 00:09:01,880 --> 00:09:05,240 Speaker 1: bounces off something like hits an obstruction, in which case 169 00:09:05,320 --> 00:09:09,360 Speaker 1: that obstruction is past the edge. And so this is 170 00:09:09,400 --> 00:09:11,720 Speaker 1: sort of an argument that suggests that the universe must 171 00:09:11,800 --> 00:09:13,880 Speaker 1: be infinite. Oh, I see, it's kind of like um 172 00:09:14,160 --> 00:09:16,880 Speaker 1: testing how big your your your house is. You know, 173 00:09:17,120 --> 00:09:19,320 Speaker 1: if you walk and you hit a fence, throw a 174 00:09:19,360 --> 00:09:22,160 Speaker 1: javelin and if it hits something good, jump the fence 175 00:09:22,280 --> 00:09:24,000 Speaker 1: and see if there's another fence. Is that kind of 176 00:09:24,000 --> 00:09:26,960 Speaker 1: what you mean? Yeah, precisely. This argument is essentially trying 177 00:09:27,000 --> 00:09:30,600 Speaker 1: to say that it's nonsense for the universe to be finite. 178 00:09:30,880 --> 00:09:33,280 Speaker 1: There is no way in which an edge makes any 179 00:09:33,320 --> 00:09:36,120 Speaker 1: sense at all, because if you get to an edge, 180 00:09:36,360 --> 00:09:39,160 Speaker 1: then you know, you have to think what's past it? Uh, 181 00:09:39,200 --> 00:09:41,240 Speaker 1: And the javelin is sort of a way to probe it. Now, 182 00:09:41,240 --> 00:09:44,280 Speaker 1: that argument of course, totally flawed. It's not approved to 183 00:09:44,360 --> 00:09:47,840 Speaker 1: the universe into Greek. Wrong, What do you can't prove 184 00:09:47,880 --> 00:09:50,920 Speaker 1: that the universe is infinite with the javelin? Turns out 185 00:09:51,400 --> 00:09:56,480 Speaker 1: we have learned one or two things since ancient times. Yeah, 186 00:09:57,160 --> 00:09:59,280 Speaker 1: and we'll get into it in much more detail. But 187 00:09:59,360 --> 00:10:02,120 Speaker 1: the essential idea is that this is flawed because the 188 00:10:02,200 --> 00:10:05,040 Speaker 1: universe could be closed. It could be to the universe 189 00:10:05,120 --> 00:10:07,560 Speaker 1: or loops on itself, and you could keep throwing that 190 00:10:07,640 --> 00:10:09,680 Speaker 1: javelin and picking it up and throwing it and picking 191 00:10:09,679 --> 00:10:13,760 Speaker 1: it up and throwing it forever, even in a finite universe. Interesting, 192 00:10:13,880 --> 00:10:16,240 Speaker 1: it is possible. You're saying for the universe to have 193 00:10:16,480 --> 00:10:19,120 Speaker 1: a wall at the end. I actually do think that 194 00:10:19,120 --> 00:10:21,960 Speaker 1: that's not nonsense. It's possible for the universe to have 195 00:10:22,040 --> 00:10:24,680 Speaker 1: a wall. But I think the simpler idea is for 196 00:10:24,720 --> 00:10:27,360 Speaker 1: the universe to sort of just be closed on itself, 197 00:10:27,400 --> 00:10:29,679 Speaker 1: like on the surface of a sphere. You know, if 198 00:10:29,720 --> 00:10:32,000 Speaker 1: you're gonna throw javelin and then follow it and pick 199 00:10:32,000 --> 00:10:33,400 Speaker 1: it up and throw it, you could do that on 200 00:10:33,440 --> 00:10:36,760 Speaker 1: the surface of the Earth basically forever without hitting a wall. 201 00:10:37,240 --> 00:10:40,679 Speaker 1: That doesn't mean the Earth is infinite. It's not all right, Well, 202 00:10:40,760 --> 00:10:43,640 Speaker 1: let's get into the different scenarios for what the universe 203 00:10:43,720 --> 00:10:47,520 Speaker 1: can look like, whether it's infinite or not infinite or finite. 204 00:10:48,200 --> 00:10:49,959 Speaker 1: But it's kind of a big question, right, It's kind 205 00:10:49,960 --> 00:10:52,199 Speaker 1: of a deep question whether or not the universe goes 206 00:10:52,240 --> 00:10:55,320 Speaker 1: on forever or whether it has a limit. But we 207 00:10:55,320 --> 00:10:57,800 Speaker 1: were wondering, you know, we kind of would like to wonder, hear, 208 00:10:57,920 --> 00:11:00,480 Speaker 1: how important is this is? This question? And does it 209 00:11:00,520 --> 00:11:03,199 Speaker 1: really matter to people? Yeah, so I walked around campus 210 00:11:03,360 --> 00:11:05,680 Speaker 1: and instead of asking them if they thought the universe 211 00:11:05,800 --> 00:11:08,760 Speaker 1: was infinite, I asked them if it mattered to them, 212 00:11:09,000 --> 00:11:10,800 Speaker 1: does it make a difference in your life if the 213 00:11:10,880 --> 00:11:15,360 Speaker 1: universe goes on literally forever or is just really really big? 214 00:11:15,840 --> 00:11:17,600 Speaker 1: And then I asked them if they wanted to know 215 00:11:17,679 --> 00:11:19,679 Speaker 1: the answer? And I think they replies to that we're 216 00:11:19,760 --> 00:11:22,400 Speaker 1: quite revealing. You asked them a two part question. First, 217 00:11:22,440 --> 00:11:24,240 Speaker 1: you asked him the technical one, and then you asked 218 00:11:24,280 --> 00:11:26,480 Speaker 1: them if they wanted to know the answer. All right, well, 219 00:11:26,760 --> 00:11:28,440 Speaker 1: think about it. Does if you listening, think about it 220 00:11:28,440 --> 00:11:30,800 Speaker 1: for a second, do you think the universe is infinite 221 00:11:30,920 --> 00:11:33,320 Speaker 1: or just really big? And would you want to know 222 00:11:33,440 --> 00:11:37,080 Speaker 1: the answer either way? Here's what people have to say. 223 00:11:37,440 --> 00:11:42,560 Speaker 1: I think it does matter because it changes the scale 224 00:11:42,559 --> 00:11:45,520 Speaker 1: of how it's just it's just weird to think that 225 00:11:45,640 --> 00:11:48,840 Speaker 1: it's infinite. You can't really see that it's infinite, but 226 00:11:48,880 --> 00:11:53,960 Speaker 1: it's just endless to me. No, No, it's interesting, but 227 00:11:54,160 --> 00:11:58,520 Speaker 1: it doesn't urge me to care. Which the answer is no, 228 00:11:58,720 --> 00:12:03,320 Speaker 1: not really. It's interesting, but not really, not really. But 229 00:12:03,400 --> 00:12:05,840 Speaker 1: do you want to know? Yes, So why do you 230 00:12:05,840 --> 00:12:08,880 Speaker 1: want to know if it doesn't make a difference. I 231 00:12:08,880 --> 00:12:10,960 Speaker 1: don't know. It's a question nobody can really answer right now, 232 00:12:11,040 --> 00:12:13,520 Speaker 1: and I just think that's the first time I definitely 233 00:12:13,520 --> 00:12:16,600 Speaker 1: want to know, but it doesn't influence my everyday to life. 234 00:12:16,800 --> 00:12:19,800 Speaker 1: So then why do you want to know out of curiosity? 235 00:12:19,920 --> 00:12:24,920 Speaker 1: I don't like not knowing things. I think that's the 236 00:12:24,920 --> 00:12:28,480 Speaker 1: whole reason they joined physics to gain more knowledge about 237 00:12:28,480 --> 00:12:30,200 Speaker 1: the universe that we live in. I think it'd be 238 00:12:30,240 --> 00:12:33,600 Speaker 1: cool to know, but it doesn't really affect me. So 239 00:12:33,640 --> 00:12:35,679 Speaker 1: why is it cool to know there's a higher or 240 00:12:35,679 --> 00:12:39,600 Speaker 1: lower chance of like finding like a new planet, or 241 00:12:39,880 --> 00:12:43,080 Speaker 1: maybe like there's a higher chance of finding aliens? I'd 242 00:12:43,080 --> 00:12:45,400 Speaker 1: say on a day to day no, probably not. But 243 00:12:45,440 --> 00:12:47,559 Speaker 1: do you want to know that? The answer I think 244 00:12:47,559 --> 00:12:49,079 Speaker 1: I would like to know the answer. Why do you 245 00:12:49,120 --> 00:12:50,520 Speaker 1: want to know? Because it would be nice to be 246 00:12:50,520 --> 00:12:52,760 Speaker 1: able to say that I know whether or not it's 247 00:12:52,840 --> 00:12:57,240 Speaker 1: infinite or just unfathomedly lige alright, No, do you want 248 00:12:57,240 --> 00:12:59,199 Speaker 1: to know the answer? Though? Yeah? So what do you 249 00:12:59,240 --> 00:13:01,240 Speaker 1: want to know the answer? Just because you always want 250 00:13:01,280 --> 00:13:04,280 Speaker 1: to know the answers to everything? I think if it 251 00:13:04,440 --> 00:13:07,320 Speaker 1: is infinite, that would blow my mind. I would be 252 00:13:07,400 --> 00:13:09,560 Speaker 1: interested in knowing the answer to that. Yeah, alright, So 253 00:13:09,600 --> 00:13:11,520 Speaker 1: why do you want to know? I think I'm someone 254 00:13:11,559 --> 00:13:14,240 Speaker 1: who just likes to know things, and it's it's hard 255 00:13:14,280 --> 00:13:17,000 Speaker 1: to actually articulate the reasons for that, but because it 256 00:13:17,000 --> 00:13:23,640 Speaker 1: doesn't matter to me personally, but I'm intellectually curious. Al right. Well, 257 00:13:23,800 --> 00:13:26,160 Speaker 1: it seems like people answered both of your questions. The 258 00:13:26,240 --> 00:13:30,000 Speaker 1: answered whether they thought that the universe was infinite or 259 00:13:30,040 --> 00:13:32,520 Speaker 1: just really big, and whether or not they wanted to 260 00:13:32,559 --> 00:13:34,920 Speaker 1: know the answer, and they were both kind of different. Yeah, 261 00:13:35,040 --> 00:13:37,280 Speaker 1: most people felt like, no, of course, it doesn't make 262 00:13:37,320 --> 00:13:39,600 Speaker 1: a difference. You know, it doesn't change how you're going 263 00:13:39,679 --> 00:13:41,679 Speaker 1: to live your life. It doesn't mean you should eat 264 00:13:41,720 --> 00:13:43,120 Speaker 1: it in is when they're green or when they have 265 00:13:43,160 --> 00:13:47,280 Speaker 1: spots in them. Right, there's no practical difference. Um. But 266 00:13:47,320 --> 00:13:49,360 Speaker 1: then when I asked people if they wanted to know 267 00:13:49,440 --> 00:13:52,040 Speaker 1: the answer, they perked up and maybe they thought like 268 00:13:52,080 --> 00:13:56,960 Speaker 1: I had the answer and I could totally he teased 269 00:13:57,000 --> 00:13:59,280 Speaker 1: them and then you let them down. But the thing 270 00:13:59,360 --> 00:14:02,560 Speaker 1: is you should have seen the curiosity in their eyes, like, 271 00:14:02,920 --> 00:14:05,800 Speaker 1: imagine knowing for a moment they imagine what would be 272 00:14:05,880 --> 00:14:10,760 Speaker 1: like to learn that truth that could change your relationship 273 00:14:10,880 --> 00:14:12,760 Speaker 1: with the cosmos? Right, And I think a lot of 274 00:14:12,800 --> 00:14:15,920 Speaker 1: people put that really well. One of my favorite responses 275 00:14:16,240 --> 00:14:18,360 Speaker 1: was the guy who said that I'm someone who likes 276 00:14:18,400 --> 00:14:21,120 Speaker 1: to know things, and it's hard to articulate the reason why, 277 00:14:21,560 --> 00:14:24,080 Speaker 1: but it is something really deep, you know that you'd 278 00:14:24,080 --> 00:14:27,200 Speaker 1: like to know. Interesting. Yeah, I guess it. So most people, 279 00:14:27,200 --> 00:14:30,240 Speaker 1: it seems, acknowledge that knowing whether the universe is infinite 280 00:14:30,320 --> 00:14:32,360 Speaker 1: or not won't make a difference in their lives. But 281 00:14:32,440 --> 00:14:35,440 Speaker 1: everyone still wants to know. Everybody wants to know, and 282 00:14:35,560 --> 00:14:38,000 Speaker 1: I want to know. Yeah, there is sort of an 283 00:14:38,000 --> 00:14:42,520 Speaker 1: inherent curiosity in people. Yeah, and I think this being 284 00:14:42,520 --> 00:14:45,600 Speaker 1: one of the biggest of questions really touches on that because, 285 00:14:45,800 --> 00:14:47,960 Speaker 1: as we were saying before, I think it connects to 286 00:14:47,960 --> 00:14:50,720 Speaker 1: our curiosity not just about ourselves, but about this place 287 00:14:50,760 --> 00:14:53,160 Speaker 1: we live in. And it's sort of the biggest question 288 00:14:53,200 --> 00:14:55,720 Speaker 1: about the biggest topic. And so that were they disappointed 289 00:14:55,760 --> 00:14:59,080 Speaker 1: that you didn't know the answer to this question, that 290 00:14:59,160 --> 00:15:01,880 Speaker 1: you wouldn't give it to the I said, hey, you 291 00:15:01,880 --> 00:15:06,080 Speaker 1: got to tune into the podcast. So yeah, I did. 292 00:15:06,200 --> 00:15:10,160 Speaker 1: Let at a time, You're you're teasing one listener at 293 00:15:10,160 --> 00:15:14,040 Speaker 1: a time. I did leave these people disappointed, unfortunately, you know, 294 00:15:14,200 --> 00:15:16,440 Speaker 1: but hey, if they listen to podcast, maybe they can 295 00:15:16,560 --> 00:15:19,400 Speaker 1: understand something about what we do know about the nature 296 00:15:19,400 --> 00:15:21,400 Speaker 1: of this question. Well, it seems like there are only 297 00:15:21,440 --> 00:15:24,920 Speaker 1: two options. Either the universe is really big or the 298 00:15:25,000 --> 00:15:27,760 Speaker 1: universe is infinite. There's there's sort of no third option, 299 00:15:27,880 --> 00:15:30,760 Speaker 1: is there, I guess? So, yeah, the third option is, 300 00:15:31,000 --> 00:15:33,440 Speaker 1: you know, the simulation when you're actually trapped in a 301 00:15:33,520 --> 00:15:35,760 Speaker 1: room somewhere in the universe is about ten feet across 302 00:15:35,800 --> 00:15:39,520 Speaker 1: and everything you're experiencing is just bologny. But now you're right, 303 00:15:40,000 --> 00:15:43,080 Speaker 1: if what we're experiencing is real and it's not a simulation, 304 00:15:43,520 --> 00:15:47,160 Speaker 1: then at the very minimum, the universe is ginormous, but 305 00:15:47,200 --> 00:15:49,680 Speaker 1: it could be really really big, or it could be 306 00:15:50,640 --> 00:15:54,240 Speaker 1: extremely infinitely big. Yeah, and there's a lot of gradations there. 307 00:15:54,240 --> 00:15:59,120 Speaker 1: It could be like ridiculously big. It could be radoculously big, 308 00:15:59,320 --> 00:16:03,440 Speaker 1: it could be like mind blowing the unfathomably big. It 309 00:16:03,480 --> 00:16:06,560 Speaker 1: could be like tend to that that big, or could 310 00:16:06,560 --> 00:16:15,000 Speaker 1: be actually infinite about tend to the ridiculous lead duntlessly big? Yeah, 311 00:16:15,040 --> 00:16:17,080 Speaker 1: I mean, any of these things. These are real numbers, 312 00:16:17,120 --> 00:16:20,240 Speaker 1: you know. And the crazy thing for me is that 313 00:16:20,440 --> 00:16:23,360 Speaker 1: one of these is true. Right, there is a truth 314 00:16:23,440 --> 00:16:26,400 Speaker 1: out there. The universe actually does have a size. Either 315 00:16:26,400 --> 00:16:29,520 Speaker 1: it's finite or it's infinite, and one of those is true, 316 00:16:29,560 --> 00:16:33,120 Speaker 1: And one day some human might actually know that truth 317 00:16:33,640 --> 00:16:36,040 Speaker 1: and have that experience that all these listeners, all those 318 00:16:36,080 --> 00:16:39,120 Speaker 1: interviewees were hoping to have. Well, I feel really teased now. 319 00:16:39,120 --> 00:16:40,440 Speaker 1: I hope you have an answer for me at the 320 00:16:40,520 --> 00:16:43,800 Speaker 1: end here, Daniel, otherwise I'm going to be disappointed as well. 321 00:16:43,920 --> 00:16:52,200 Speaker 1: The answer is fund more physics research. Give Daniel more money. 322 00:16:52,880 --> 00:16:55,240 Speaker 1: All right, Well, let's get into this question a little 323 00:16:55,240 --> 00:16:57,760 Speaker 1: bit more, and let's get into how we would know 324 00:16:58,040 --> 00:17:00,800 Speaker 1: if the universe is infinite or fine day, and what 325 00:17:00,840 --> 00:17:03,200 Speaker 1: would happen if we found out. But first let's take 326 00:17:03,240 --> 00:17:19,119 Speaker 1: a quick break, all right, Daniel we're asking the question 327 00:17:19,280 --> 00:17:22,080 Speaker 1: is the universe infinite or is it finite? And I 328 00:17:22,080 --> 00:17:25,080 Speaker 1: guess my first question is, you know, is it possible? 329 00:17:25,080 --> 00:17:27,560 Speaker 1: Which of these is possible? Are they? Are these both 330 00:17:27,640 --> 00:17:31,360 Speaker 1: possible possibilities for the universe? Can the universe be really infinite? 331 00:17:31,480 --> 00:17:33,600 Speaker 1: Or does it make sense for the universe to have 332 00:17:33,720 --> 00:17:36,080 Speaker 1: a wall at the end and be closed off? I 333 00:17:36,119 --> 00:17:39,760 Speaker 1: think unfortunately, all of these things are possible, and we 334 00:17:39,800 --> 00:17:42,440 Speaker 1: can go through the various scenarios. But you know, we're 335 00:17:42,440 --> 00:17:45,440 Speaker 1: talking about big questions here, and the questions we don't 336 00:17:45,440 --> 00:17:48,440 Speaker 1: have a lot of history in getting answers to. It's 337 00:17:48,440 --> 00:17:50,840 Speaker 1: not like we've been a lots of universes. We've seen 338 00:17:50,960 --> 00:17:53,200 Speaker 1: what happens, and we have a lot of experience where 339 00:17:53,240 --> 00:17:56,560 Speaker 1: grizzled veterans in measuring universes. Now, this is going to 340 00:17:56,640 --> 00:17:58,199 Speaker 1: be the first time if we ever do get an 341 00:17:58,240 --> 00:18:00,760 Speaker 1: answer that we would learn this about universe. So we've 342 00:18:00,760 --> 00:18:03,600 Speaker 1: got to be open minded. Things that seem crazy to 343 00:18:03,760 --> 00:18:07,320 Speaker 1: us are going to be based on our experience here, right. 344 00:18:08,040 --> 00:18:10,360 Speaker 1: So like if you think, oh, nobody has a PhD 345 00:18:10,440 --> 00:18:14,080 Speaker 1: yet on answering this question exactly, we all got to 346 00:18:14,080 --> 00:18:17,600 Speaker 1: be open minded. So anything that works mathematically, even if 347 00:18:17,640 --> 00:18:21,280 Speaker 1: it's like revolting to our physical intuition, we've got to 348 00:18:21,280 --> 00:18:23,680 Speaker 1: be open to it because well, we've been making progress. 349 00:18:23,760 --> 00:18:26,600 Speaker 1: Right before, we thought the universe was just us, and 350 00:18:26,600 --> 00:18:29,000 Speaker 1: then we find out that it's the size of the galaxy, 351 00:18:29,000 --> 00:18:31,200 Speaker 1: and then we find out there's more galaxy. So I 352 00:18:31,560 --> 00:18:35,480 Speaker 1: feel like our understanding of how big the universe is 353 00:18:35,560 --> 00:18:38,600 Speaker 1: has been getting bigger progressively. Yeah, we've been biggering and 354 00:18:38,640 --> 00:18:42,560 Speaker 1: biggering our imagination of the universe. But still all that is, 355 00:18:42,720 --> 00:18:45,679 Speaker 1: it doesn't really address the question of whether it's finite 356 00:18:45,800 --> 00:18:49,480 Speaker 1: or whether it's actually infinite. That just sort of increases 357 00:18:49,560 --> 00:18:51,840 Speaker 1: the sort of minimum distance of the universe as we 358 00:18:51,880 --> 00:18:54,800 Speaker 1: look further and further out. So you know, So to 359 00:18:54,800 --> 00:18:57,720 Speaker 1: answer your question, the universe could we finite or could 360 00:18:57,720 --> 00:19:00,320 Speaker 1: be infinite? Both of those things are possible. Well, let's 361 00:19:00,320 --> 00:19:02,359 Speaker 1: cycle each one at a time and and see what 362 00:19:02,480 --> 00:19:05,200 Speaker 1: each one would need. So let's say the let's let's 363 00:19:05,200 --> 00:19:09,479 Speaker 1: assume the universe is finite, meaning that there is a 364 00:19:09,520 --> 00:19:13,520 Speaker 1: limited amount of space in space um and and that 365 00:19:13,600 --> 00:19:16,280 Speaker 1: the universe doesn't go on forever. At some point, uh 366 00:19:16,400 --> 00:19:18,520 Speaker 1: it ends, it has like a volume like a set 367 00:19:18,760 --> 00:19:22,360 Speaker 1: number that's the volume of the universe. Is that possible? 368 00:19:22,440 --> 00:19:24,400 Speaker 1: Wouldn't that mean that there's like a wall at the end. 369 00:19:24,440 --> 00:19:26,240 Speaker 1: And if there's a wall, what's the on the other 370 00:19:26,280 --> 00:19:29,840 Speaker 1: side of the wall. You're gonna take your javel and 371 00:19:29,880 --> 00:19:32,960 Speaker 1: you're gonna go to that wall and you're gonna poke it. Right, Yeah, 372 00:19:33,040 --> 00:19:36,520 Speaker 1: I'm gonna spend forty billion years traveling just to throw 373 00:19:36,560 --> 00:19:39,480 Speaker 1: that javelin. Well, you have to remember what we're talking 374 00:19:39,480 --> 00:19:42,639 Speaker 1: about here is the shape of space, and space is 375 00:19:42,680 --> 00:19:46,080 Speaker 1: not nothing. It's not emptiness. Right. Space is a thing 376 00:19:46,160 --> 00:19:49,440 Speaker 1: that we are existing. It is the background on which 377 00:19:49,480 --> 00:19:52,360 Speaker 1: all of this physics happens. But it's not nothing. It's dynamical. 378 00:19:52,840 --> 00:19:55,280 Speaker 1: It can twist and bend and ripple and do all 379 00:19:55,320 --> 00:19:58,280 Speaker 1: sorts of crazy stuff. It's got like substance to that 380 00:19:58,600 --> 00:20:01,040 Speaker 1: to it, right, the space of universe. I don't know 381 00:20:01,040 --> 00:20:03,399 Speaker 1: if substance is the right word, but it has a 382 00:20:03,560 --> 00:20:06,960 Speaker 1: nature to it. It's not nothing. I see, there's there 383 00:20:07,080 --> 00:20:10,560 Speaker 1: is nothing, like literally nothing, and then there's space, which 384 00:20:10,560 --> 00:20:15,000 Speaker 1: has something we don't know if nothing is a physical possibility, right, 385 00:20:15,359 --> 00:20:17,880 Speaker 1: So when we're talking about like the edge of space, yes, 386 00:20:17,920 --> 00:20:22,080 Speaker 1: it's possible for space to be finite in different ways. 387 00:20:22,520 --> 00:20:24,960 Speaker 1: In one way, it could have an edge, like you 388 00:20:24,960 --> 00:20:27,200 Speaker 1: could just like you get to the edge of space 389 00:20:27,280 --> 00:20:30,160 Speaker 1: and there's and that's it. Now you might ask, well, 390 00:20:30,200 --> 00:20:32,600 Speaker 1: what's beyond it? Well, the answer could be that there's nothing. 391 00:20:32,640 --> 00:20:35,200 Speaker 1: There is not a thing beyond it. It's like when 392 00:20:35,240 --> 00:20:37,439 Speaker 1: you get to the north pole and you want to 393 00:20:37,480 --> 00:20:40,439 Speaker 1: go more north, there's just no more northiness to go. 394 00:20:40,760 --> 00:20:43,040 Speaker 1: Couldn't it be like like an like an island, and 395 00:20:43,080 --> 00:20:44,919 Speaker 1: you get to the edge of an island and beyond 396 00:20:44,960 --> 00:20:48,160 Speaker 1: that there's nothingness. It could be an island. The edge 397 00:20:48,160 --> 00:20:50,600 Speaker 1: is defined by the water, right, So what's the water 398 00:20:50,640 --> 00:20:52,879 Speaker 1: in this analogy, right, Well, the water could be nothing, 399 00:20:53,640 --> 00:20:55,840 Speaker 1: and then space could be something. Yeah, but then you've 400 00:20:55,920 --> 00:20:59,320 Speaker 1: sort of just redefined space to be the nothingness, and 401 00:20:59,320 --> 00:21:01,480 Speaker 1: then you could ask how far does that nothing go on? 402 00:21:01,720 --> 00:21:04,800 Speaker 1: Doesn't really answer the question, but there's a real possibility 403 00:21:04,840 --> 00:21:06,639 Speaker 1: that space is all there is, that there is that 404 00:21:06,720 --> 00:21:09,560 Speaker 1: nothing isn't an option that there's space and then there's 405 00:21:09,600 --> 00:21:12,240 Speaker 1: space and there's not. There's no place where there's no space. 406 00:21:12,760 --> 00:21:17,359 Speaker 1: Nothing is not an option by that's a confusing sentence. 407 00:21:17,440 --> 00:21:19,439 Speaker 1: And then you just you get to that edge and 408 00:21:19,480 --> 00:21:21,520 Speaker 1: you just can't go any further. Like what happens if 409 00:21:21,520 --> 00:21:23,760 Speaker 1: you try to keep going, you just what you would 410 00:21:23,760 --> 00:21:26,440 Speaker 1: not go anywhere. Maybe it's helpful to think about other 411 00:21:26,480 --> 00:21:29,639 Speaker 1: examples where space is not simply connected, like in a 412 00:21:29,680 --> 00:21:32,400 Speaker 1: black hole. If you're in a black hole, you can 413 00:21:32,440 --> 00:21:34,920 Speaker 1: only go in one direction. You can only go closer 414 00:21:35,000 --> 00:21:36,919 Speaker 1: to the center of the black hole, because that's the 415 00:21:36,960 --> 00:21:40,040 Speaker 1: only path the shape of space will allow. It's not 416 00:21:40,119 --> 00:21:42,720 Speaker 1: just that the gravity is really strong. It's the bending 417 00:21:42,760 --> 00:21:45,439 Speaker 1: of space that makes that means that every path points 418 00:21:45,440 --> 00:21:47,720 Speaker 1: towards the center of the black hole, right, and so 419 00:21:47,760 --> 00:21:49,639 Speaker 1: in the same way, if you've got to like the 420 00:21:49,760 --> 00:21:52,320 Speaker 1: edge of the universe, it just means that there's nowhere 421 00:21:52,359 --> 00:21:56,879 Speaker 1: to go but back or sideways. I see, like the 422 00:21:56,960 --> 00:21:59,760 Speaker 1: universe might redirect you. Yeah, like what happens when you 423 00:21:59,760 --> 00:22:02,040 Speaker 1: get to the edge of the subway system right where 424 00:22:02,080 --> 00:22:04,480 Speaker 1: you either you know, ride it back or you transfer 425 00:22:04,520 --> 00:22:06,760 Speaker 1: to another line. Like you would throw a javelin at 426 00:22:06,760 --> 00:22:08,360 Speaker 1: the edge of the universe and it would just get 427 00:22:08,359 --> 00:22:10,919 Speaker 1: deflected to the side maybe or come back at you 428 00:22:10,960 --> 00:22:13,679 Speaker 1: and spirit. Yeah, And that doesn't mean that there's a 429 00:22:13,680 --> 00:22:16,719 Speaker 1: wall they're holding it in. It just means space ends. 430 00:22:17,320 --> 00:22:21,280 Speaker 1: That's a total possibility. Space gets spacey or wonky at 431 00:22:21,320 --> 00:22:24,520 Speaker 1: the edges. Yeah, it gets because space is about it's 432 00:22:24,520 --> 00:22:27,719 Speaker 1: about the relative connections of these pieces, right, It's not 433 00:22:27,840 --> 00:22:30,800 Speaker 1: an emptiness. It's a thing where it's like this fluid 434 00:22:30,840 --> 00:22:33,960 Speaker 1: we're moving through. And what we're talking about is the 435 00:22:34,000 --> 00:22:37,280 Speaker 1: curvature space, the connectedness of space, the topology of it, 436 00:22:37,320 --> 00:22:39,600 Speaker 1: if you want to get technical, how it's connected to 437 00:22:39,640 --> 00:22:43,320 Speaker 1: other bits, and and that changes, right, that changes when 438 00:22:43,359 --> 00:22:46,159 Speaker 1: you put mass in something, it changes how that stuff 439 00:22:46,200 --> 00:22:48,520 Speaker 1: is connected. All right. So that's one possibility is that 440 00:22:48,600 --> 00:22:51,480 Speaker 1: the universe is finite with an edge that is kind 441 00:22:51,520 --> 00:22:54,200 Speaker 1: of wonking doesn't let you poke through it. Yeah, that 442 00:22:54,240 --> 00:22:57,200 Speaker 1: would be really weird and awesome to discover. But it 443 00:22:57,240 --> 00:22:59,879 Speaker 1: could also be finite in the way the surface of 444 00:22:59,880 --> 00:23:02,280 Speaker 1: the Earth is finite but doesn't have an edge. And 445 00:23:02,320 --> 00:23:04,600 Speaker 1: then it could be we call that closed. It could 446 00:23:04,600 --> 00:23:07,959 Speaker 1: be essentially be curved. And we know that that space 447 00:23:08,040 --> 00:23:11,720 Speaker 1: could be curved, right, gravity and energy bends it, and 448 00:23:11,720 --> 00:23:13,280 Speaker 1: so it could just be that you keep going and 449 00:23:13,320 --> 00:23:15,720 Speaker 1: you just sort of loop back to where you started. Right. 450 00:23:15,760 --> 00:23:18,080 Speaker 1: It's like asking what is the length of a circle, 451 00:23:18,200 --> 00:23:20,280 Speaker 1: Like if you take a leg the string string and 452 00:23:20,320 --> 00:23:23,200 Speaker 1: you tie it to itself into a circle, like, what's 453 00:23:23,240 --> 00:23:26,640 Speaker 1: the length of it. It's finite, but it's not um 454 00:23:26,680 --> 00:23:29,480 Speaker 1: like a set number because it just goes around and around. Yeah, 455 00:23:29,480 --> 00:23:31,800 Speaker 1: and it doesn't have an edge, right, there's no wonky 456 00:23:31,840 --> 00:23:34,639 Speaker 1: bit there. You just keep going. And so that's totally 457 00:23:34,640 --> 00:23:38,479 Speaker 1: possible and that is consistent. If space curves in a 458 00:23:38,520 --> 00:23:42,359 Speaker 1: certain way, then it can loop back on itself. And 459 00:23:42,400 --> 00:23:45,000 Speaker 1: so we're talking about now, is this curvature of space 460 00:23:45,080 --> 00:23:48,959 Speaker 1: is really important in understanding the possible shapes of the universe, 461 00:23:48,960 --> 00:23:52,640 Speaker 1: which determine the possible sizes, right, because if, for example, 462 00:23:53,040 --> 00:23:55,479 Speaker 1: space is curved in that way it's like the surface 463 00:23:55,480 --> 00:23:58,600 Speaker 1: of a sphere, then it can't be infinite. It cannot 464 00:23:59,240 --> 00:24:01,520 Speaker 1: if space is curve, right, If space is curved like 465 00:24:01,560 --> 00:24:03,920 Speaker 1: the surface of the sphere, then it cannot be infinite. Yeah, 466 00:24:03,920 --> 00:24:06,560 Speaker 1: then it would have to be closed and therefore finite. 467 00:24:06,880 --> 00:24:09,840 Speaker 1: Really couldn't it be like a spiral like it's curved, 468 00:24:09,840 --> 00:24:13,320 Speaker 1: but it just keeps spiraling outwards forever, like fucilit pasta 469 00:24:13,480 --> 00:24:17,160 Speaker 1: or something. Yeah, Like just take a string and keep 470 00:24:17,359 --> 00:24:22,840 Speaker 1: spiraling it up. It's interesting. Um, you can have topologies 471 00:24:22,880 --> 00:24:26,280 Speaker 1: that are like a donut, you know, a bagel or 472 00:24:26,320 --> 00:24:29,040 Speaker 1: something that have positive curvature, but that's still like a 473 00:24:29,280 --> 00:24:32,280 Speaker 1: like a like a like a seashell, you know, like 474 00:24:32,320 --> 00:24:36,640 Speaker 1: it just keep sparling out folding outwards. Isn't it possible 475 00:24:36,640 --> 00:24:39,080 Speaker 1: to Yeah, I wonder about that, you know, or like 476 00:24:39,359 --> 00:24:42,919 Speaker 1: the surface of a cylinder, surface of a cylinder is 477 00:24:42,960 --> 00:24:48,000 Speaker 1: also um curved, but could go on forever, But then 478 00:24:48,000 --> 00:24:50,359 Speaker 1: the curvature would only be in one dimension. So I 479 00:24:50,440 --> 00:24:54,440 Speaker 1: think if the curvature is sort of even in every direction, 480 00:24:54,760 --> 00:24:57,080 Speaker 1: then then the sphere is the only a sphere or 481 00:24:57,119 --> 00:25:00,000 Speaker 1: a toroid is the only shape that's consistent with that curvature. 482 00:25:00,359 --> 00:25:02,280 Speaker 1: What if it looks like a slinky, you know, like 483 00:25:02,320 --> 00:25:05,720 Speaker 1: a like a spring, then it could be finite, infinite 484 00:25:05,720 --> 00:25:08,600 Speaker 1: and curved. Well, but I think the slinky is essentially 485 00:25:08,640 --> 00:25:11,480 Speaker 1: the same topologically as a straight cylinder. It's just sort 486 00:25:11,520 --> 00:25:14,720 Speaker 1: of bent in another space, and that doesn't have curature 487 00:25:14,760 --> 00:25:18,159 Speaker 1: in every direction. But we're when we're talking about measuring 488 00:25:18,160 --> 00:25:20,080 Speaker 1: the curvature of space, it's something innate and it would 489 00:25:20,119 --> 00:25:22,159 Speaker 1: be the same in every direction. Oh, I see. If 490 00:25:22,160 --> 00:25:25,320 Speaker 1: it's if it's curved inwards in all directions, then you 491 00:25:25,400 --> 00:25:27,399 Speaker 1: sort of have to fold in on itself. And so 492 00:25:27,400 --> 00:25:30,000 Speaker 1: that's another possibility, right, the universe could be finite and 493 00:25:30,040 --> 00:25:32,040 Speaker 1: have a wonky edge, or it could be finite and 494 00:25:32,080 --> 00:25:35,439 Speaker 1: be closed on itself. Um and like the surface of 495 00:25:35,440 --> 00:25:38,480 Speaker 1: a sphere without any edges. So that that's how a 496 00:25:38,560 --> 00:25:42,399 Speaker 1: finite universe can make sense without imagining like a giant 497 00:25:42,400 --> 00:25:45,560 Speaker 1: brick wall at the end, which doesn't make sense. Yeah. Yeah, 498 00:25:45,600 --> 00:25:47,480 Speaker 1: And but and you say you always like to say 499 00:25:47,520 --> 00:25:50,840 Speaker 1: that this possibility that the universe is finite, it's sort 500 00:25:50,840 --> 00:25:54,160 Speaker 1: of maybe comforting to human brains, but it is kind 501 00:25:54,160 --> 00:25:58,120 Speaker 1: of a crazy idea, the idea that the universe ends 502 00:25:58,160 --> 00:26:00,720 Speaker 1: at some point, or that there there's it doesn't go 503 00:26:00,720 --> 00:26:02,840 Speaker 1: on forever. Yeah. Do you think it's comforting to think 504 00:26:02,840 --> 00:26:05,720 Speaker 1: that the universe is finite because because infinity is hard 505 00:26:05,720 --> 00:26:09,560 Speaker 1: to imagine? Yeah, I mean infinity is kind of scary, right, 506 00:26:09,720 --> 00:26:11,880 Speaker 1: It's like it's like living in an infinite house. It's 507 00:26:11,920 --> 00:26:17,680 Speaker 1: like a nightmare. The electricity bill, yeah, the cleaning bill, 508 00:26:17,720 --> 00:26:21,879 Speaker 1: and the how many beds you have to buy, how 509 00:26:21,920 --> 00:26:25,480 Speaker 1: many I kea furniture a dress as you have to build. 510 00:26:25,600 --> 00:26:28,320 Speaker 1: I mean, it's a it's the stuff nightmares are made up. 511 00:26:28,359 --> 00:26:31,840 Speaker 1: You could literally be building furniture forever. Yeah, and once 512 00:26:31,880 --> 00:26:34,560 Speaker 1: you lose your keys, they're just gone. Man, They're gone. 513 00:26:34,760 --> 00:26:37,199 Speaker 1: That's true. I'm not sure which is more comforting, But 514 00:26:37,280 --> 00:26:39,720 Speaker 1: I think the idea of a finite universe is really 515 00:26:39,760 --> 00:26:43,359 Speaker 1: odd because then there's a number, right, the universe would 516 00:26:43,400 --> 00:26:45,399 Speaker 1: have a size, And then you have to ask, like 517 00:26:45,600 --> 00:26:48,920 Speaker 1: why that number? Why not seven times that number or 518 00:26:49,080 --> 00:26:52,600 Speaker 1: half that number? What is important about that number? And 519 00:26:52,640 --> 00:26:54,879 Speaker 1: you wonder like is it random or is it fixed? 520 00:26:54,920 --> 00:26:57,359 Speaker 1: Is it determined by something? Right? It would there would 521 00:26:57,359 --> 00:27:01,600 Speaker 1: be like a fixed number of uh, you know, electrons 522 00:27:01,640 --> 00:27:04,600 Speaker 1: in it. You know, like there would be uh seven 523 00:27:04,680 --> 00:27:10,800 Speaker 1: point three trillion point one and not one electron more 524 00:27:10,920 --> 00:27:14,320 Speaker 1: or less, right is there? Yeah? That's what makes a 525 00:27:14,320 --> 00:27:18,120 Speaker 1: physicist worry. It's just hard to grapple with. But that's 526 00:27:18,119 --> 00:27:20,679 Speaker 1: why we're doing physics, right. We're asking these really basic 527 00:27:20,760 --> 00:27:23,439 Speaker 1: questions about the universe so that then we can do 528 00:27:23,520 --> 00:27:25,520 Speaker 1: the philosophy. Is so that then we can like do 529 00:27:25,560 --> 00:27:28,720 Speaker 1: the therapy. Were like, all right, turns out this is 530 00:27:28,760 --> 00:27:31,600 Speaker 1: the universe we live in. What does that mean? How 531 00:27:31,640 --> 00:27:34,040 Speaker 1: do I live my life in that kind of universe? 532 00:27:34,480 --> 00:27:35,760 Speaker 1: And does that mean that when you go to a 533 00:27:35,800 --> 00:27:38,040 Speaker 1: restaurant and you look at the menu, like the many 534 00:27:38,119 --> 00:27:41,160 Speaker 1: makes you uncomfortable, like why are there only thirteen dishes here? 535 00:27:41,480 --> 00:27:45,359 Speaker 1: Why aren't there fourteen dishes or twelve? I know that 536 00:27:45,359 --> 00:27:48,760 Speaker 1: that doesn't arise from some de fundamental principle of the universe. 537 00:27:49,080 --> 00:27:52,359 Speaker 1: That arises from some argument you know, between the managers 538 00:27:52,640 --> 00:27:54,640 Speaker 1: um when they were founding the restaurants, and not every 539 00:27:54,720 --> 00:27:59,359 Speaker 1: number you spot reveal something deep about the universe. Alright, alright, alright, 540 00:27:59,400 --> 00:28:03,160 Speaker 1: so then that's the finite possibility. So step me through 541 00:28:03,200 --> 00:28:05,919 Speaker 1: the infinite possibility, because to me, this one is the 542 00:28:05,920 --> 00:28:08,760 Speaker 1: one that seems impossible, like how can something be infinite? 543 00:28:08,800 --> 00:28:12,159 Speaker 1: But you're saying the universe could be infinite. The universe 544 00:28:12,200 --> 00:28:15,199 Speaker 1: could totally be infinite. Yeah, I mean if space is 545 00:28:15,280 --> 00:28:19,119 Speaker 1: very simple and flat, you know, like the surface of 546 00:28:19,200 --> 00:28:22,000 Speaker 1: a of a flat plane, then it could just keep 547 00:28:22,040 --> 00:28:24,359 Speaker 1: going on. It could just go on and on and on. 548 00:28:24,440 --> 00:28:27,359 Speaker 1: And in some ways, that's sort of the simplest idea 549 00:28:27,400 --> 00:28:31,359 Speaker 1: because it doesn't require an edge or complicated topology. I mean, 550 00:28:31,400 --> 00:28:34,320 Speaker 1: it requires you to somehow invent an infinite number of electrons, 551 00:28:34,359 --> 00:28:36,119 Speaker 1: which is you know, a whole other problem you have 552 00:28:36,160 --> 00:28:40,080 Speaker 1: to tackle at something like an infinite amount of energy, right, 553 00:28:40,280 --> 00:28:45,520 Speaker 1: and matter and possibilities like there's it means that there 554 00:28:45,560 --> 00:28:48,320 Speaker 1: are versions of this Earth somewhere out there in the 555 00:28:48,360 --> 00:28:51,240 Speaker 1: same universe as us. And if you had a lot 556 00:28:51,240 --> 00:28:54,240 Speaker 1: of experience measuring universes and finding them to be finite, 557 00:28:54,240 --> 00:28:58,000 Speaker 1: I would understand your skepticism. Right, But you have exactly 558 00:28:58,040 --> 00:29:00,200 Speaker 1: the same experience that everybody else has, which is you 559 00:29:00,240 --> 00:29:03,080 Speaker 1: have no idea how big a universe should be or 560 00:29:03,080 --> 00:29:06,479 Speaker 1: whether it's weird to have an infinite universe, And so 561 00:29:06,560 --> 00:29:08,719 Speaker 1: it could totally be and it could be very natural. 562 00:29:09,360 --> 00:29:13,280 Speaker 1: You're saying that that I don't have a PhD in universizing. 563 00:29:14,120 --> 00:29:16,720 Speaker 1: You have an incredible array of talents, but that is 564 00:29:16,760 --> 00:29:21,920 Speaker 1: not one of them. Well, um, all right, so I 565 00:29:21,920 --> 00:29:24,120 Speaker 1: guess as a physicist you kind of have to treat 566 00:29:24,160 --> 00:29:28,040 Speaker 1: all possibilities. Is possible? You know, if it's possible, then 567 00:29:28,080 --> 00:29:30,520 Speaker 1: it's a possibility. Yeah, And so all you can do 568 00:29:30,560 --> 00:29:33,360 Speaker 1: is say, what's possible, what would make sense from the 569 00:29:33,360 --> 00:29:36,040 Speaker 1: physics point of view, what can we make work, you know, 570 00:29:36,160 --> 00:29:39,080 Speaker 1: mathematically and theoretically, And then you go out and you 571 00:29:39,160 --> 00:29:41,680 Speaker 1: confront those theories with the data, and you say well, 572 00:29:41,920 --> 00:29:44,080 Speaker 1: do they predict something we can measure it is there's 573 00:29:44,080 --> 00:29:46,000 Speaker 1: something in the universe out there that can give us 574 00:29:46,040 --> 00:29:49,040 Speaker 1: a clue as to which of these scenarios we are 575 00:29:49,080 --> 00:29:52,600 Speaker 1: actually living in, right, because there might be clues out 576 00:29:52,640 --> 00:29:55,600 Speaker 1: there that tell you whether the universe is finite or 577 00:29:55,640 --> 00:29:57,880 Speaker 1: infinite without having to go to the edge to check 578 00:29:58,280 --> 00:30:00,880 Speaker 1: that's right. We certainly can learn think about this question 579 00:30:00,920 --> 00:30:04,600 Speaker 1: by doing actual measurements that don't involve javelins. Well, what 580 00:30:04,680 --> 00:30:07,000 Speaker 1: do we know right now about the universe? Like, how 581 00:30:07,040 --> 00:30:08,960 Speaker 1: how big do we think it is? As as we 582 00:30:09,000 --> 00:30:10,680 Speaker 1: know it right now? How big do you do we 583 00:30:10,720 --> 00:30:13,160 Speaker 1: think it is? Well, we've been looking out into space 584 00:30:13,200 --> 00:30:15,680 Speaker 1: for a while and we have these really clever tools 585 00:30:15,760 --> 00:30:18,880 Speaker 1: now for measuring how far away stuff is. You know, 586 00:30:18,960 --> 00:30:21,400 Speaker 1: we can we talked about this on the podcast, measuring 587 00:30:21,400 --> 00:30:24,480 Speaker 1: the distance to nearby stars by basically looking at them 588 00:30:24,480 --> 00:30:28,240 Speaker 1: in two ways like binocular vision, and then using supernovas 589 00:30:28,280 --> 00:30:30,719 Speaker 1: and stuff to measure the distance to even further stuff. 590 00:30:31,200 --> 00:30:33,000 Speaker 1: So basically what we can do is we can ask, 591 00:30:33,120 --> 00:30:35,960 Speaker 1: like how far out can we see? That sets a 592 00:30:36,120 --> 00:30:38,680 Speaker 1: minimum size for the universe, just like you know, what's 593 00:30:38,720 --> 00:30:43,000 Speaker 1: the observable universe? Right? Like what's the furthest thing that 594 00:30:43,080 --> 00:30:45,680 Speaker 1: we can see with our eyes or telescopes, And that 595 00:30:45,720 --> 00:30:48,360 Speaker 1: tells us at least the universe has to be that big. 596 00:30:48,560 --> 00:30:51,200 Speaker 1: That's right, And your naive calculation might be, well, it 597 00:30:51,280 --> 00:30:54,440 Speaker 1: must be the speed of light times the age of 598 00:30:54,480 --> 00:30:57,280 Speaker 1: the universe, which is almost fourteen billion years, and so 599 00:30:57,320 --> 00:31:01,040 Speaker 1: you might think, oh, it's a sphere for billion light 600 00:31:01,160 --> 00:31:04,760 Speaker 1: years in radius, but that's actually an underestimate. The universe 601 00:31:04,920 --> 00:31:08,040 Speaker 1: that we can see is much much bigger than that. Right, 602 00:31:08,080 --> 00:31:13,720 Speaker 1: that is so naive, Daniel, That's like what a third 603 00:31:13,800 --> 00:31:16,880 Speaker 1: year gradu stude in physics might think. But no, I 604 00:31:16,880 --> 00:31:18,200 Speaker 1: don't mean to be kind of saying at all. I 605 00:31:18,200 --> 00:31:20,480 Speaker 1: mean like that would make a lot of sense that 606 00:31:20,480 --> 00:31:22,560 Speaker 1: that's all we can see because light has to travel 607 00:31:22,560 --> 00:31:24,080 Speaker 1: here from those places. And we talk a lot in 608 00:31:24,120 --> 00:31:27,440 Speaker 1: the podcast about how you know, the further away you look, 609 00:31:27,480 --> 00:31:30,080 Speaker 1: the further back in time you're looking at, eventually you 610 00:31:30,200 --> 00:31:32,760 Speaker 1: run out of time. The universe is not infinitely old, 611 00:31:33,160 --> 00:31:35,280 Speaker 1: so stuff that's really far away just hasn't had a 612 00:31:35,360 --> 00:31:38,000 Speaker 1: chance to get here. Yeah, well that's how how how 613 00:31:38,000 --> 00:31:41,000 Speaker 1: many we would think it would be. But you're saying 614 00:31:41,000 --> 00:31:44,800 Speaker 1: that we can tell the size by how far the 615 00:31:44,880 --> 00:31:47,360 Speaker 1: then the furthest thing we can see is yeah, and 616 00:31:47,360 --> 00:31:50,400 Speaker 1: it turns out that stuff is further away than the 617 00:31:50,520 --> 00:31:52,920 Speaker 1: age of the universe times the speed of light. Because 618 00:31:52,920 --> 00:31:56,400 Speaker 1: the universe is not static, it's expanding. Stuff is moving 619 00:31:56,440 --> 00:31:59,160 Speaker 1: away from us. So light has gotten to us from 620 00:31:59,200 --> 00:32:02,960 Speaker 1: stuff that is how further away than the speed of 621 00:32:03,080 --> 00:32:05,959 Speaker 1: light times the age of the universe Because we know that, right, 622 00:32:05,960 --> 00:32:08,520 Speaker 1: whether it's finite or infinite, we know it's getting bigger. 623 00:32:08,640 --> 00:32:11,400 Speaker 1: We know it's stretching, it's expanding, it's getting more spread out. 624 00:32:11,800 --> 00:32:14,840 Speaker 1: So the furthest we can see is about forty three 625 00:32:15,040 --> 00:32:19,200 Speaker 1: billion light years away or or I guess twenty one 626 00:32:19,440 --> 00:32:22,440 Speaker 1: billion light years each way, No, it's forty three billion 627 00:32:22,520 --> 00:32:25,440 Speaker 1: light years in radius. So it's a diameter of more 628 00:32:25,480 --> 00:32:28,880 Speaker 1: than ninety billion light years across, which is I mean, 629 00:32:28,920 --> 00:32:31,560 Speaker 1: it's a huge number. Like why anybody even need more 630 00:32:31,680 --> 00:32:36,920 Speaker 1: universe than that? Well, depends on how many Daniel and 631 00:32:37,000 --> 00:32:40,160 Speaker 1: jorgees you want? You want. We've got big plans here. 632 00:32:40,200 --> 00:32:43,680 Speaker 1: Folks need a more room. We need we need more 633 00:32:43,760 --> 00:32:47,040 Speaker 1: of us obviously, all right, So our current estimate of 634 00:32:47,080 --> 00:32:51,840 Speaker 1: how big the universe is is ninety six billion light years. 635 00:32:51,840 --> 00:32:55,160 Speaker 1: What meaning it would take you right now ninety six 636 00:32:55,240 --> 00:32:57,560 Speaker 1: billion years to go from one end to the other 637 00:32:57,760 --> 00:33:00,320 Speaker 1: or more, I guess since it's growing. It's growing. Yeah, 638 00:33:00,320 --> 00:33:02,680 Speaker 1: so you couldn't actually go from one edge of the 639 00:33:02,680 --> 00:33:05,760 Speaker 1: observed universe to the other because it's growing in space 640 00:33:05,840 --> 00:33:08,840 Speaker 1: is expanding faster than like can move through it. So 641 00:33:08,920 --> 00:33:11,160 Speaker 1: a photon on one edge of the of the universe 642 00:33:11,400 --> 00:33:14,200 Speaker 1: will never reach the other side of the observable universe. 643 00:33:14,720 --> 00:33:17,000 Speaker 1: So we know at least it right now, as far 644 00:33:17,040 --> 00:33:20,400 Speaker 1: as we know, is eight six billion light years y. Yeah, 645 00:33:20,480 --> 00:33:22,880 Speaker 1: and that's the minimum, right, So that's an at least 646 00:33:22,960 --> 00:33:25,520 Speaker 1: and that's already a really big number. But we know 647 00:33:25,640 --> 00:33:28,040 Speaker 1: something else about the universe, which is really important. We 648 00:33:28,080 --> 00:33:30,120 Speaker 1: know not just how far we can see. We know 649 00:33:30,240 --> 00:33:33,040 Speaker 1: something about the shape of space. We know like how 650 00:33:33,160 --> 00:33:36,400 Speaker 1: things are curving. All right, let's get into the shape 651 00:33:36,400 --> 00:33:40,000 Speaker 1: of space and how shapely it is and whether or 652 00:33:40,000 --> 00:33:43,040 Speaker 1: not it is actually infinite or just crazy big. But 653 00:33:43,120 --> 00:33:58,480 Speaker 1: first let's take another quick break, all right, Daniel, So 654 00:33:58,520 --> 00:34:00,920 Speaker 1: we know that the universe right now, or at least 655 00:34:00,920 --> 00:34:04,400 Speaker 1: at some point is at least eighty six billion light 656 00:34:04,480 --> 00:34:06,760 Speaker 1: years wide, but we don't know if it if it 657 00:34:06,840 --> 00:34:10,960 Speaker 1: keeps going on much more than that, or a little 658 00:34:10,960 --> 00:34:14,759 Speaker 1: bit after that, or maybe that it's actually infinite and 659 00:34:14,800 --> 00:34:17,520 Speaker 1: it goes on forever beyond eighty six billion light years 660 00:34:18,480 --> 00:34:21,080 Speaker 1: that we can see. And so I guess the question is, 661 00:34:21,120 --> 00:34:23,279 Speaker 1: how could we even tell, you know, we're sitting here 662 00:34:23,280 --> 00:34:27,040 Speaker 1: in this little rock and this tiny galaxy, how could 663 00:34:27,040 --> 00:34:30,960 Speaker 1: we possibly tell whether the universe goes on forever or not, 664 00:34:31,200 --> 00:34:34,839 Speaker 1: because we can't really get travel is far, you know, 665 00:34:34,880 --> 00:34:37,880 Speaker 1: forever to check. Yeah, you're right, in some sense, we 666 00:34:37,920 --> 00:34:41,879 Speaker 1: know literally nothing about what's passed there. Like there could 667 00:34:41,960 --> 00:34:45,720 Speaker 1: be crazy blue dragons the size of galaxies out there 668 00:34:45,960 --> 00:34:48,480 Speaker 1: and we would have no information about it because photons 669 00:34:48,560 --> 00:34:52,560 Speaker 1: from those dragons haven't reached our eyeballs, and so almost 670 00:34:52,640 --> 00:34:56,720 Speaker 1: anything could be happening outside the observable universe. So any 671 00:34:56,840 --> 00:34:59,320 Speaker 1: argument we're gonna make, it's gonna be sort of frustratingly 672 00:34:59,480 --> 00:35:01,759 Speaker 1: in direc act because we can't go out there. And 673 00:35:01,760 --> 00:35:06,040 Speaker 1: even if you wait another billion years the observable universe grows, 674 00:35:06,120 --> 00:35:08,879 Speaker 1: we can see more of it, will never literally never 675 00:35:09,000 --> 00:35:11,399 Speaker 1: see all of it. Right, It's not like we will 676 00:35:11,640 --> 00:35:14,640 Speaker 1: could ever prove directly that the universe is infinite. So 677 00:35:14,640 --> 00:35:18,480 Speaker 1: it's going to rely on some sort of more indirect argument, right, 678 00:35:18,480 --> 00:35:20,239 Speaker 1: because you could send a probe out there to see 679 00:35:20,239 --> 00:35:22,360 Speaker 1: if you hit a wall or if it curves around, 680 00:35:22,520 --> 00:35:24,759 Speaker 1: but you would have to check forever to make sure 681 00:35:24,800 --> 00:35:27,520 Speaker 1: that the universe doesn't go on forever. So you could 682 00:35:27,560 --> 00:35:31,160 Speaker 1: prove that the universe is finite, but you can't prove directly, 683 00:35:31,200 --> 00:35:33,680 Speaker 1: at least that it's infinite. Like you could send a 684 00:35:33,680 --> 00:35:35,880 Speaker 1: probe out there and it does hit a wall, or 685 00:35:36,200 --> 00:35:38,479 Speaker 1: it loops back around itself and comes back to Earth 686 00:35:38,520 --> 00:35:41,879 Speaker 1: and it's very surprised. Right, You could you could make 687 00:35:41,920 --> 00:35:43,759 Speaker 1: that kind of demonstration, and people have looked, you know, 688 00:35:43,800 --> 00:35:45,839 Speaker 1: they've looked out of the space to see like our 689 00:35:45,880 --> 00:35:48,680 Speaker 1: stars repeating, do you see the same pattern over and 690 00:35:48,760 --> 00:35:51,319 Speaker 1: over again, which would suggest that the universe is sort 691 00:35:51,320 --> 00:35:54,600 Speaker 1: of small and finite and that light is zoomed through 692 00:35:54,600 --> 00:35:56,640 Speaker 1: it a few times in the history of the universe. 693 00:35:57,000 --> 00:36:00,239 Speaker 1: So you could prove that it's finite, but direct that 694 00:36:00,280 --> 00:36:04,560 Speaker 1: it's infinite is actually impossible. Wow, that's a little disturbing. 695 00:36:04,800 --> 00:36:07,480 Speaker 1: But we can make some interesting arguments, right. You know 696 00:36:07,520 --> 00:36:09,919 Speaker 1: you said before you were making arguments before about how 697 00:36:10,320 --> 00:36:13,360 Speaker 1: unusual or unnatural infinity is we can make sort of 698 00:36:13,440 --> 00:36:16,840 Speaker 1: the opposite set of arguments. We could argue that infinity 699 00:36:16,920 --> 00:36:21,040 Speaker 1: is actually the most natural explanation. You can find some 700 00:36:21,200 --> 00:36:25,359 Speaker 1: mathematical proof that the universe is infinite. You mean, like, 701 00:36:25,400 --> 00:36:27,880 Speaker 1: from what we can tell about the nature of the universe, 702 00:36:27,960 --> 00:36:30,759 Speaker 1: it says our formulas say that the universe should be 703 00:36:30,840 --> 00:36:34,440 Speaker 1: infinite or finite. Yeah, you can make that kind of argument. 704 00:36:34,440 --> 00:36:38,080 Speaker 1: And while that argument will never be like a satisfactory 705 00:36:38,120 --> 00:36:41,000 Speaker 1: because you can't ever prove that something is infinite, it 706 00:36:41,040 --> 00:36:44,040 Speaker 1: could still be pretty satisfactory. And a lot of other 707 00:36:44,120 --> 00:36:47,120 Speaker 1: things in physics or in science at least we accept 708 00:36:47,160 --> 00:36:50,520 Speaker 1: with the same level of proof. For example, we think 709 00:36:51,000 --> 00:36:53,719 Speaker 1: that momentum is conserved everywhere in the universe. You know, 710 00:36:53,760 --> 00:36:55,920 Speaker 1: we think that every time things bump into each other, 711 00:36:56,239 --> 00:36:58,759 Speaker 1: that the momentum is the same before and after. We 712 00:36:58,800 --> 00:37:02,160 Speaker 1: haven't checked every and all time rocks bump into each other, 713 00:37:02,360 --> 00:37:05,680 Speaker 1: the momentum didn't leak out of the universe somewhere, right, 714 00:37:05,719 --> 00:37:09,279 Speaker 1: We have a fundamental principle. There's a symmetry about translational 715 00:37:09,280 --> 00:37:13,840 Speaker 1: invariance that we invoke that we believe, and that momentum conservation, 716 00:37:13,880 --> 00:37:16,160 Speaker 1: momentum is a consequence of it. So in a similar way, 717 00:37:16,480 --> 00:37:19,719 Speaker 1: we make some argument that implies the universe has to 718 00:37:19,719 --> 00:37:23,160 Speaker 1: be infinite, then maybe we could believe it. I see, like, 719 00:37:23,239 --> 00:37:27,960 Speaker 1: maybe if a conservation of momentum uh necessitates like it 720 00:37:28,040 --> 00:37:30,360 Speaker 1: needs for the universe to be infinite for it to 721 00:37:30,360 --> 00:37:32,239 Speaker 1: be true, then we might as well say that, yes, 722 00:37:32,239 --> 00:37:35,320 Speaker 1: the universe is infinite, because if you believe conservation of momentum, 723 00:37:35,320 --> 00:37:37,719 Speaker 1: then you have to believe that the universe is infinite. Yes, 724 00:37:37,760 --> 00:37:39,920 Speaker 1: and I have to necessitate that, right, So you need 725 00:37:40,200 --> 00:37:43,920 Speaker 1: some theory of how the universe works that requires the 726 00:37:44,000 --> 00:37:46,840 Speaker 1: universe to be infinite. That so the theory only works 727 00:37:46,960 --> 00:37:49,960 Speaker 1: if the universe is infinite. And then you need to 728 00:37:50,040 --> 00:37:53,239 Speaker 1: rule out all other possible theories um and show that 729 00:37:53,280 --> 00:37:56,359 Speaker 1: the data are consistent with your theory that requires an 730 00:37:56,360 --> 00:38:00,440 Speaker 1: infinite universe. And in that case you could convince yourself 731 00:38:00,440 --> 00:38:02,480 Speaker 1: that the universe is infinite. If you had the right 732 00:38:02,520 --> 00:38:05,720 Speaker 1: pH D thesis, you could make the you could convince 733 00:38:05,800 --> 00:38:08,279 Speaker 1: yourself of anything. Yeah, And so I went around and 734 00:38:08,280 --> 00:38:11,560 Speaker 1: I actually asked cosmologists this question, you know, said, can 735 00:38:11,560 --> 00:38:14,520 Speaker 1: you imagine a theory of inflation or of the early 736 00:38:14,640 --> 00:38:18,960 Speaker 1: universe or cosmology that only works if the universe is infinite, 737 00:38:19,320 --> 00:38:23,879 Speaker 1: and that stumped all of them. Really, they couldn't imagine it. Well, 738 00:38:24,040 --> 00:38:26,800 Speaker 1: we have a theory of the universe. It's inflation. That's 739 00:38:26,920 --> 00:38:30,040 Speaker 1: most natural if the universe is infinite, but it could 740 00:38:30,080 --> 00:38:33,200 Speaker 1: probably work in a finite universe also, it can work 741 00:38:33,239 --> 00:38:37,280 Speaker 1: either way. It doesn't assume an edge. It doesn't assume 742 00:38:37,320 --> 00:38:39,840 Speaker 1: an edge or curvature. And you know, we've measured the 743 00:38:39,840 --> 00:38:43,040 Speaker 1: curvature of the universe and we've measured to be really flat, 744 00:38:43,120 --> 00:38:46,520 Speaker 1: like very very very very flat, and that's consistent with 745 00:38:46,560 --> 00:38:48,640 Speaker 1: what we think happened the very beginning of the universe. 746 00:38:48,719 --> 00:38:51,160 Speaker 1: We think the universe expanded really really quickly and that 747 00:38:51,320 --> 00:38:54,920 Speaker 1: stretched everything out um. But to cosmologists, the universe is 748 00:38:54,960 --> 00:38:59,319 Speaker 1: either infinite or like ridiculously big, like we're on the 749 00:38:59,360 --> 00:39:02,520 Speaker 1: surface of a huge sphere. And to them, it doesn't 750 00:39:02,560 --> 00:39:06,400 Speaker 1: really make that much difference for their calculations because theologists. 751 00:39:06,480 --> 00:39:10,560 Speaker 1: For the cosmologists, oh man, so everyday people care more 752 00:39:10,600 --> 00:39:13,399 Speaker 1: about whether the universe is fine it are infinite than cosmologist. 753 00:39:13,800 --> 00:39:15,520 Speaker 1: Well that's funny because I asked them, like, does it 754 00:39:15,600 --> 00:39:17,279 Speaker 1: make a difference to your theory whether the universe is 755 00:39:17,320 --> 00:39:20,520 Speaker 1: actually infinite or just really vast, like you know, like 756 00:39:20,680 --> 00:39:22,640 Speaker 1: it seems flat because we're on the surface of a 757 00:39:22,719 --> 00:39:25,319 Speaker 1: huge sphere, but it's actually not and it is. No, 758 00:39:25,360 --> 00:39:27,080 Speaker 1: it doesn't make any difference. And then I said, well, 759 00:39:27,200 --> 00:39:29,000 Speaker 1: would you like to know the answer? And then they 760 00:39:29,000 --> 00:39:32,560 Speaker 1: were like, oh, of course I'm curious, you know, And 761 00:39:32,600 --> 00:39:36,560 Speaker 1: so in that way they share this wondering curiosity, right, 762 00:39:36,680 --> 00:39:40,560 Speaker 1: even though it doesn't affect their job either, even as cosmologist. 763 00:39:40,600 --> 00:39:42,760 Speaker 1: That's right. But I did get an estimate, an estimate 764 00:39:43,000 --> 00:39:45,920 Speaker 1: of of how crazy the idea his or or what 765 00:39:46,000 --> 00:39:48,600 Speaker 1: this theory would look like. No, an estimate for sort 766 00:39:48,600 --> 00:39:51,399 Speaker 1: of the minimum size of the universe, given that what 767 00:39:51,440 --> 00:39:55,040 Speaker 1: we've measured is that the universe seems flat, than either 768 00:39:55,280 --> 00:39:59,200 Speaker 1: the universe is infinite or it's at least ten to 769 00:39:59,360 --> 00:40:03,040 Speaker 1: the ten to the ten to the hundred and twenty 770 00:40:03,080 --> 00:40:10,200 Speaker 1: two megaparsex wide. What And that's an that's an argument 771 00:40:10,280 --> 00:40:13,560 Speaker 1: from like looking at the quantum fluctuations in the early 772 00:40:13,680 --> 00:40:16,960 Speaker 1: universe and asking how did those blow up to give 773 00:40:17,040 --> 00:40:19,680 Speaker 1: us the universe that we have now, and if so, 774 00:40:19,880 --> 00:40:22,880 Speaker 1: how much must it have blown up? And that's the 775 00:40:22,960 --> 00:40:26,120 Speaker 1: number they come up with so if you ask its cosmologies, 776 00:40:27,040 --> 00:40:29,680 Speaker 1: people who think about the universe and the beginning of it, 777 00:40:29,920 --> 00:40:33,000 Speaker 1: they have a minimum size of the universe. Some of 778 00:40:33,040 --> 00:40:35,720 Speaker 1: them do. This is not like a widely believed numbers, 779 00:40:35,920 --> 00:40:38,759 Speaker 1: just like an estimate some of them, I see. But 780 00:40:39,640 --> 00:40:41,960 Speaker 1: so some of them, based on what they know about 781 00:40:41,960 --> 00:40:44,440 Speaker 1: the universe, they think that the universe has to be 782 00:40:44,520 --> 00:40:48,319 Speaker 1: at least that humongous number big. That's right. But but 783 00:40:48,400 --> 00:40:51,680 Speaker 1: I think another interesting thing to understand is that to cosmologists, 784 00:40:51,719 --> 00:40:54,319 Speaker 1: the universe being infinite is sort of the default. It's 785 00:40:54,360 --> 00:40:56,640 Speaker 1: the idea that makes the most sense to them. They 786 00:40:56,680 --> 00:40:59,000 Speaker 1: have no trouble with that at all. And the reason 787 00:40:59,080 --> 00:41:02,160 Speaker 1: is that they invoke a very basic argument. They say, look, 788 00:41:02,200 --> 00:41:05,680 Speaker 1: the universe should be the same everywhere, and if the 789 00:41:05,800 --> 00:41:08,560 Speaker 1: universe is finite, then you ask questions like why is 790 00:41:08,560 --> 00:41:10,239 Speaker 1: it finite? Why is it here? Why is it not 791 00:41:10,320 --> 00:41:13,960 Speaker 1: over there? And so this sort of like universal principle 792 00:41:14,080 --> 00:41:17,279 Speaker 1: the universe should look the same everywhere, makes it very 793 00:41:17,360 --> 00:41:20,640 Speaker 1: natural for them to think of the universe as being infinite. Right, 794 00:41:20,719 --> 00:41:22,759 Speaker 1: I'm a little suspicious, Daniel. I feel like you asked 795 00:41:22,800 --> 00:41:26,840 Speaker 1: this because those becausemologies and they they they believe the 796 00:41:26,920 --> 00:41:28,839 Speaker 1: universe is infinite. But when you pro them to give 797 00:41:28,880 --> 00:41:30,960 Speaker 1: you a minimum number, they just gave you a ridiculous, 798 00:41:31,520 --> 00:41:35,880 Speaker 1: made up, fake number. I mean, what kind of numbers 799 00:41:35,920 --> 00:41:37,560 Speaker 1: like ten to the tent to the tent to the tent. 800 00:41:37,640 --> 00:41:39,320 Speaker 1: That's that sounds like they just pull that out of 801 00:41:39,360 --> 00:41:42,400 Speaker 1: their pocket. Well, you know, you can read the paper 802 00:41:42,640 --> 00:41:46,000 Speaker 1: will link to it from this episode, and there actually 803 00:41:46,120 --> 00:41:48,120 Speaker 1: is a calculation there, you know, and you start from 804 00:41:48,160 --> 00:41:50,840 Speaker 1: small quantum fluctuations and what we know about the expansion 805 00:41:50,840 --> 00:41:53,200 Speaker 1: of the universe, and if you want to get a 806 00:41:53,280 --> 00:41:56,880 Speaker 1: universe that's this flat where space really does seem flat 807 00:41:56,920 --> 00:41:59,520 Speaker 1: than either it's infinite or you're on the surface of 808 00:41:59,560 --> 00:42:03,080 Speaker 1: a doncillous the big sphere of radius. I don't even 809 00:42:03,120 --> 00:42:05,200 Speaker 1: know what you name that. Oh, I see what you're saying. 810 00:42:05,200 --> 00:42:07,759 Speaker 1: You're saying that if the universe is finite, then we 811 00:42:07,800 --> 00:42:10,960 Speaker 1: would see more curvature in it, because that's the only 812 00:42:11,200 --> 00:42:14,400 Speaker 1: way to explain the finite universes is kind of the 813 00:42:14,400 --> 00:42:18,399 Speaker 1: sphere or tourist type of thing. Oh I see, nice, 814 00:42:18,480 --> 00:42:20,080 Speaker 1: but the only so, the only way to explain the 815 00:42:20,120 --> 00:42:24,040 Speaker 1: flatness that we see is by either assuming the universe 816 00:42:24,080 --> 00:42:28,440 Speaker 1: is infinite or it's a ridiculous number. Yes, And I 817 00:42:28,480 --> 00:42:32,359 Speaker 1: hold that hope that you know, someday these cosmologists will 818 00:42:32,400 --> 00:42:34,280 Speaker 1: think of a reason and will think of a way 819 00:42:34,640 --> 00:42:39,160 Speaker 1: to actually test the infinitude of the universe. Infinitude that 820 00:42:39,200 --> 00:42:42,840 Speaker 1: sounds like like a I don't know, like a brand 821 00:42:42,880 --> 00:42:47,200 Speaker 1: of of of a sound equipment or something. It sounds 822 00:42:47,239 --> 00:42:49,359 Speaker 1: like sneakers that Bill and Teddible were in their next 823 00:42:49,400 --> 00:42:52,760 Speaker 1: great adventure. But you know, we're in the early days 824 00:42:52,760 --> 00:42:55,600 Speaker 1: of understanding this question. You know, we don't understand how 825 00:42:55,640 --> 00:42:57,600 Speaker 1: the universe came to be. There as a lot of 826 00:42:57,600 --> 00:43:00,920 Speaker 1: possible constraints there. If we understood the mechanism that created 827 00:43:00,960 --> 00:43:03,960 Speaker 1: the universe and started inflation, then we can answer questions 828 00:43:04,000 --> 00:43:06,360 Speaker 1: like is it reasonable to have an infinite number of 829 00:43:06,400 --> 00:43:09,839 Speaker 1: electrons or just ten to the seventy jillion? And so 830 00:43:10,080 --> 00:43:12,319 Speaker 1: there's a lot more information coming down the pike, and 831 00:43:12,360 --> 00:43:14,759 Speaker 1: so I'm optimistic that one day we will know the 832 00:43:14,760 --> 00:43:17,120 Speaker 1: answer to this question. All right, Well, it sounds kind 833 00:43:17,120 --> 00:43:19,640 Speaker 1: of like you guys are leaning towards infinite, you know, 834 00:43:20,160 --> 00:43:22,520 Speaker 1: it definitely sounds like we should all be preparing our 835 00:43:22,600 --> 00:43:26,000 Speaker 1: brains for the fact that this is an infinite universe 836 00:43:26,120 --> 00:43:28,479 Speaker 1: and there there's an infinite number of mees out there 837 00:43:28,520 --> 00:43:33,600 Speaker 1: in other earths, repeating itself after a while. I hope, 838 00:43:33,640 --> 00:43:35,840 Speaker 1: so you know, I hope the universe goes on forever. 839 00:43:35,920 --> 00:43:39,160 Speaker 1: It'd be sort of claustrophobic mentally to imagine that there's 840 00:43:39,200 --> 00:43:41,319 Speaker 1: a limited amount of stuff. You know, that if we 841 00:43:41,440 --> 00:43:44,080 Speaker 1: somehow we're able to travel the stars, that there's like 842 00:43:44,120 --> 00:43:46,919 Speaker 1: a full list of all the stars you could visit, 843 00:43:46,960 --> 00:43:49,520 Speaker 1: and of course it'd be a big number. But it's 844 00:43:49,560 --> 00:43:52,239 Speaker 1: not that comfortable to imagine that there's an end to 845 00:43:52,320 --> 00:43:54,200 Speaker 1: that list, that at some point you'd be like, well, 846 00:43:54,280 --> 00:43:56,479 Speaker 1: I've done them all, kind of like this episode, which 847 00:43:56,520 --> 00:43:59,560 Speaker 1: we have to wrap up soon because it's not infinite 848 00:44:00,040 --> 00:44:02,800 Speaker 1: amount of time we have and too bad, right, wouldn't 849 00:44:02,840 --> 00:44:08,480 Speaker 1: you just like to talk forever? Well? Are you sure? 850 00:44:08,600 --> 00:44:11,239 Speaker 1: But what people like to listen to us forever? A 851 00:44:11,280 --> 00:44:16,440 Speaker 1: couple of dudes talking friend infinitude. Daniel and Jorgey Talk Forever, 852 00:44:18,040 --> 00:44:22,440 Speaker 1: the longest podcast ever. It's just a continuous stream that 853 00:44:23,480 --> 00:44:24,879 Speaker 1: and you'll never get to the end of it because 854 00:44:24,880 --> 00:44:28,240 Speaker 1: we keep talking. If you started after we already began talking, 855 00:44:28,280 --> 00:44:30,960 Speaker 1: you'll never catch up, right right, And after a while 856 00:44:31,000 --> 00:44:34,120 Speaker 1: we just keep repeating the same jokes, although I don't 857 00:44:34,120 --> 00:44:36,640 Speaker 1: think you need an infinite universe for that thing, or 858 00:44:36,680 --> 00:44:40,719 Speaker 1: a podcast. We've already we already closed the curvature of that. 859 00:44:41,520 --> 00:44:44,880 Speaker 1: I think we've measured the curvature of this podcast. Yeah, 860 00:44:44,920 --> 00:44:48,680 Speaker 1: it's fairly round. It's about fifty podcasts episodes before we 861 00:44:48,719 --> 00:44:50,799 Speaker 1: start repeating the jokes. But I think this is one 862 00:44:50,840 --> 00:44:53,000 Speaker 1: of my funnest questions because it really does touch on 863 00:44:53,040 --> 00:44:56,920 Speaker 1: our innate curiosity, our desire to understand the way the 864 00:44:56,920 --> 00:44:59,400 Speaker 1: world works and our place in it, you know, And 865 00:44:59,440 --> 00:45:03,960 Speaker 1: are we totally insignificant or are we just very insignificant? 866 00:45:04,080 --> 00:45:06,279 Speaker 1: And that's an important question. All right, Well, but in 867 00:45:06,320 --> 00:45:08,239 Speaker 1: this universe, we want to thank you for joining us, 868 00:45:08,239 --> 00:45:10,200 Speaker 1: and we hope you enjoyed that. Thanks to everyone for 869 00:45:10,239 --> 00:45:12,800 Speaker 1: tuning in and for lending us a non infinite slice 870 00:45:12,840 --> 00:45:22,879 Speaker 1: of your day. Before you still have a question after 871 00:45:22,960 --> 00:45:26,080 Speaker 1: listening to all these explanations, please drop us a line. 872 00:45:26,120 --> 00:45:28,279 Speaker 1: We'd love to hear from you. You can find us 873 00:45:28,280 --> 00:45:32,040 Speaker 1: on Facebook, Twitter, and Instagram at Daniel and Jorge that's 874 00:45:32,080 --> 00:45:35,480 Speaker 1: one word, or email us at Feedback at Daniel and 875 00:45:35,600 --> 00:45:39,040 Speaker 1: Jorge dot com. Thanks for listening, and remember that Daniel 876 00:45:39,080 --> 00:45:41,560 Speaker 1: and Jorge Explain the Universe is a production of I 877 00:45:41,800 --> 00:45:45,239 Speaker 1: Heart Radio. For more podcast from my heart Radio, visit 878 00:45:45,280 --> 00:45:49,160 Speaker 1: the i heart Radio Apple Podcasts, or wherever you listen 879 00:45:49,239 --> 00:45:55,799 Speaker 1: to your favorite shows. Yeah.