1 00:00:08,440 --> 00:00:10,680 Speaker 1: Hey, Daniel, you own a cat, right? You know we 2 00:00:10,800 --> 00:00:13,200 Speaker 1: used to have a cat, but no longer. Oh no, 3 00:00:13,360 --> 00:00:16,800 Speaker 1: what happened local pack of coyotes? I'm afraid? Whoa where 4 00:00:16,840 --> 00:00:20,760 Speaker 1: do you live? And to the wild. We have colonized 5 00:00:20,800 --> 00:00:23,320 Speaker 1: the wild and turned it into suburbs. Yeah, it is 6 00:00:23,320 --> 00:00:25,720 Speaker 1: a concrete jungle out there. But I wonder is that 7 00:00:25,800 --> 00:00:27,880 Speaker 1: really the whole story or is there more to it? 8 00:00:28,200 --> 00:00:30,040 Speaker 1: What do you mean? What are you accusing me of? 9 00:00:30,240 --> 00:00:32,519 Speaker 1: I don't know. I think cats and physicists. It never 10 00:00:32,520 --> 00:00:35,080 Speaker 1: seems to go, well, did you do some kind of 11 00:00:35,080 --> 00:00:37,280 Speaker 1: crazy experiment on the cat? I did have a cat, 12 00:00:37,400 --> 00:00:39,279 Speaker 1: and I did have a box. Whether or not I 13 00:00:39,320 --> 00:00:42,400 Speaker 1: did that experiment, I'd rather not say. Maybe you did 14 00:00:42,440 --> 00:00:45,760 Speaker 1: and maybe you didn't both at the same time. Now 15 00:00:45,800 --> 00:00:47,760 Speaker 1: I'm feeling boxed in. But you know, if we live 16 00:00:47,760 --> 00:00:51,879 Speaker 1: in a multiverse, technically there are probably cat physicists out there, 17 00:00:52,080 --> 00:00:56,000 Speaker 1: maybe experimenting on human pets or what did the aliens 18 00:00:56,040 --> 00:00:58,120 Speaker 1: that come to visit Earth are cats? What are you 19 00:00:58,120 --> 00:01:00,560 Speaker 1: gonna do? Maybe the coyotes will protect us. That's like 20 00:01:00,600 --> 00:01:04,400 Speaker 1: the idea for an animated movie. Cats versus coyotes versus physicists. 21 00:01:19,680 --> 00:01:23,080 Speaker 1: Hi I'm Jory mccartoonists and the creator of PhD Comics. Hi. 22 00:01:23,200 --> 00:01:25,800 Speaker 1: I'm Daniel. I'm a particle physicist and a professor at 23 00:01:25,880 --> 00:01:29,319 Speaker 1: UC Irvine, and I really do miss my cats. Oh 24 00:01:29,400 --> 00:01:32,160 Speaker 1: you had multiple cats? Is it starting to feel like 25 00:01:32,200 --> 00:01:35,160 Speaker 1: a trend here, like a string of clues? Not just 26 00:01:35,280 --> 00:01:38,760 Speaker 1: one cat in multiple superpositions, but two cats at the 27 00:01:38,800 --> 00:01:42,080 Speaker 1: same time, which we've lost both the same summer. Oh, no, 28 00:01:42,360 --> 00:01:44,920 Speaker 1: to coyotes, both of them, I'm afraid. So we had 29 00:01:44,959 --> 00:01:48,600 Speaker 1: indoor outdoor cats in Chicago, where it's pretty safe, very 30 00:01:48,600 --> 00:01:51,600 Speaker 1: few coyotes, but when we moved to Irvine, they didn't 31 00:01:51,600 --> 00:01:53,840 Speaker 1: really last very long. We tried to keep them inside 32 00:01:53,840 --> 00:01:56,200 Speaker 1: for a while, but it just wasn't possible. You need 33 00:01:56,240 --> 00:01:58,760 Speaker 1: to get coyotes for pets, you know, just move up 34 00:01:58,800 --> 00:02:02,760 Speaker 1: the food chain. Coyotes and raccoons. Yeah, those are great ideas. 35 00:02:05,320 --> 00:02:07,280 Speaker 1: I mean, that's kind of what dogs are, sort of. 36 00:02:07,480 --> 00:02:09,640 Speaker 1: What's the difference between a kyote and a dog? I 37 00:02:09,680 --> 00:02:14,359 Speaker 1: think several thousands of years of breeding that can come 38 00:02:14,400 --> 00:02:16,960 Speaker 1: in handy. But anyways, welcome to our podcast, Daniel and 39 00:02:17,040 --> 00:02:20,440 Speaker 1: Jorge Explain the Universe, a production of iHeartRadio in which 40 00:02:20,440 --> 00:02:23,359 Speaker 1: we do our best to tame the wild universe out 41 00:02:23,400 --> 00:02:26,480 Speaker 1: there with all of its crazy feral physics, everything that's 42 00:02:26,480 --> 00:02:29,720 Speaker 1: happening out there in the universe, the crazy quantum frothing 43 00:02:29,800 --> 00:02:32,359 Speaker 1: foam all the way up to the huge black holes 44 00:02:32,440 --> 00:02:35,799 Speaker 1: sucking up enormous amounts of gas and dust. We want 45 00:02:35,840 --> 00:02:38,000 Speaker 1: to tame all of that and try to bring it 46 00:02:38,120 --> 00:02:41,400 Speaker 1: under human understanding. We want to build an explanation of 47 00:02:41,520 --> 00:02:43,560 Speaker 1: it that makes sense to our human minds, and that 48 00:02:43,639 --> 00:02:46,120 Speaker 1: lets us think about what else we could do in 49 00:02:46,160 --> 00:02:49,720 Speaker 1: this universe. It's right, the universe is a gigantic jungle 50 00:02:49,800 --> 00:02:53,280 Speaker 1: of amazing information and facts, of incredible things that are 51 00:02:53,280 --> 00:02:56,280 Speaker 1: happening out there in the cosmos between the galaxies and 52 00:02:56,320 --> 00:02:59,720 Speaker 1: the supercluster of galaxies, and also here on Earth inside 53 00:02:59,720 --> 00:03:02,680 Speaker 1: of our molecules. Scientists are there to explore and to 54 00:03:02,880 --> 00:03:05,720 Speaker 1: map out everything and us in it. That's right. We 55 00:03:05,760 --> 00:03:08,360 Speaker 1: are hacking our way through the jungle of the universe, 56 00:03:08,440 --> 00:03:10,360 Speaker 1: trying to figure out where everything is, what does the 57 00:03:10,440 --> 00:03:13,919 Speaker 1: landscape look like underneath, how has everything worked together? Though 58 00:03:13,919 --> 00:03:16,000 Speaker 1: our goal, of course, is not to pave over it 59 00:03:16,040 --> 00:03:19,560 Speaker 1: with suburbs, but just to understand it, to describe it, 60 00:03:19,600 --> 00:03:23,440 Speaker 1: to appreciate its magnificence and beauty. We're here to pave 61 00:03:23,480 --> 00:03:27,519 Speaker 1: it over with knowledge, I guess right, and curiosity. I 62 00:03:27,560 --> 00:03:29,760 Speaker 1: don't want to pave over anything, really, I mean, I 63 00:03:29,760 --> 00:03:31,680 Speaker 1: don't want to come to some alien planet and just 64 00:03:31,760 --> 00:03:34,680 Speaker 1: like cover it and concrete and Starbucks unless is pretty 65 00:03:34,720 --> 00:03:38,760 Speaker 1: inhospitable in the first place. Isn't concrete and Starbucks better 66 00:03:38,800 --> 00:03:41,600 Speaker 1: than like the serves of Venus right now? I suppose, 67 00:03:41,640 --> 00:03:43,720 Speaker 1: But you know, let Venus be Venus. Maybe there's some 68 00:03:43,800 --> 00:03:47,000 Speaker 1: kind of life form that loves sulfuric acid clouds and 69 00:03:47,080 --> 00:03:50,600 Speaker 1: super high pressures and temperatures and would be pretty offended 70 00:03:50,680 --> 00:03:54,160 Speaker 1: or even exterminated by the presence of concrete and Starbucks. 71 00:03:54,440 --> 00:03:56,960 Speaker 1: Or maybe it's just because they haven't discovered a nice 72 00:03:56,960 --> 00:03:59,520 Speaker 1: spice latting, you know, and they'd be like, oh, thank 73 00:03:59,560 --> 00:04:02,480 Speaker 1: you so much for opening my eyes to the true 74 00:04:02,480 --> 00:04:05,560 Speaker 1: wonders of the universe. Maybe it wasn't fosphine in their atmosphere, 75 00:04:05,600 --> 00:04:09,240 Speaker 1: it was pumpkin spice, after all, the beginning of a 76 00:04:09,320 --> 00:04:14,320 Speaker 1: downfall of any civilization. We've discovered Starbucks on Venus, But 77 00:04:14,400 --> 00:04:17,039 Speaker 1: it is a pretty wild universe out there, full of 78 00:04:17,240 --> 00:04:20,040 Speaker 1: undiscovered things that we can discover and learn about and 79 00:04:20,080 --> 00:04:22,720 Speaker 1: ponder about to get a better perspective of how the 80 00:04:22,800 --> 00:04:25,400 Speaker 1: universe works. And the way to get these answers is 81 00:04:25,440 --> 00:04:27,760 Speaker 1: to explore, to go out there and try to find 82 00:04:27,800 --> 00:04:30,200 Speaker 1: things that don't make sense to us, things that are new, 83 00:04:30,279 --> 00:04:33,160 Speaker 1: things that our brains can't quite yet grapple with that 84 00:04:33,200 --> 00:04:36,520 Speaker 1: our mathematical stories do not yet include, or sometimes we 85 00:04:36,560 --> 00:04:38,720 Speaker 1: try to take those mathematical stories and apply them to 86 00:04:38,800 --> 00:04:41,520 Speaker 1: things we thought we understood. But the common thread there 87 00:04:41,839 --> 00:04:44,680 Speaker 1: is asking questions. In the end, it all comes down 88 00:04:44,720 --> 00:04:48,000 Speaker 1: to people being curious and wanting to understand how the 89 00:04:48,080 --> 00:04:51,440 Speaker 1: universe works, applying our understanding to it, and asking questions 90 00:04:51,480 --> 00:04:54,440 Speaker 1: when it doesn't quite work out in their minds. That's right. 91 00:04:54,480 --> 00:04:56,919 Speaker 1: We are all explorers in this jungle of a universe, 92 00:04:56,920 --> 00:04:59,400 Speaker 1: and I guess there are our main tool for hacking 93 00:04:59,400 --> 00:05:02,760 Speaker 1: our weights through all of this mystery, our questions, Right, 94 00:05:02,920 --> 00:05:06,359 Speaker 1: questions are kind of the machete of physicists. Yeah, some 95 00:05:06,400 --> 00:05:09,880 Speaker 1: people might say the experiments are the machete, but questions 96 00:05:09,920 --> 00:05:12,240 Speaker 1: are the first step. Right. That's how you decide what 97 00:05:12,279 --> 00:05:14,360 Speaker 1: you're going to look for, That's how you decide what 98 00:05:14,480 --> 00:05:16,880 Speaker 1: experiments you're going to do. That's how you frame the 99 00:05:16,960 --> 00:05:20,720 Speaker 1: possible answers you might get to your crazy scientific questions. 100 00:05:20,839 --> 00:05:23,440 Speaker 1: So in the end, it's questions and curiosity that is 101 00:05:23,520 --> 00:05:26,520 Speaker 1: driving all of human science and maybe alien science and 102 00:05:26,720 --> 00:05:28,960 Speaker 1: coyote science. I guess you just have to make sure 103 00:05:29,000 --> 00:05:31,680 Speaker 1: that your questions are sharp, right, Like, if you had 104 00:05:31,760 --> 00:05:34,080 Speaker 1: dull questions, that wouldn't get you very far. Yeah, you 105 00:05:34,080 --> 00:05:37,279 Speaker 1: wouldn't slice through very much science jungle with a dull question. 106 00:05:37,480 --> 00:05:41,040 Speaker 1: But questions people ask, and questions scientists ask in questions 107 00:05:41,040 --> 00:05:43,360 Speaker 1: we ask here on the podcast, and sometimes we even 108 00:05:43,400 --> 00:05:46,200 Speaker 1: answer them for listeners. That's right. We want you to 109 00:05:46,240 --> 00:05:49,720 Speaker 1: be an active participant in this podcast, not just sitting 110 00:05:49,720 --> 00:05:52,160 Speaker 1: back and listening to me and Jorge joke about bananas 111 00:05:52,160 --> 00:05:55,159 Speaker 1: and talk about science, but to engage your brain, because 112 00:05:55,200 --> 00:05:57,719 Speaker 1: our goal is not just entertain you, but to really 113 00:05:57,800 --> 00:06:00,840 Speaker 1: bring a level of understanding into your mind. We want 114 00:06:00,839 --> 00:06:03,120 Speaker 1: to put these pieces into your brain and teach you 115 00:06:03,200 --> 00:06:05,359 Speaker 1: how to manipulate them so you can use them to 116 00:06:05,400 --> 00:06:08,719 Speaker 1: answer new questions, your own questions. And so we love 117 00:06:08,720 --> 00:06:10,520 Speaker 1: when listeners do that, and then they come back to 118 00:06:10,600 --> 00:06:12,400 Speaker 1: us with things that didn't quite make sense to them 119 00:06:12,520 --> 00:06:14,919 Speaker 1: that let us unravel a little bit of misunderstanding or 120 00:06:14,960 --> 00:06:17,440 Speaker 1: help them get a clear picture for how things work. 121 00:06:17,520 --> 00:06:25,960 Speaker 1: So today on the podcast we'll be tackling listener questions 122 00:06:26,360 --> 00:06:30,679 Speaker 1: number thirty seven. This is our thirty seventh listener question episode. 123 00:06:30,920 --> 00:06:33,719 Speaker 1: Absolutely and if you have a question that you have 124 00:06:33,839 --> 00:06:36,360 Speaker 1: been wondering about, please don't be shy right to us 125 00:06:36,400 --> 00:06:39,479 Speaker 1: to questions at Daniel d Jorge dot com. We really 126 00:06:39,480 --> 00:06:42,000 Speaker 1: do write back emails to all of our listener questions 127 00:06:42,000 --> 00:06:44,000 Speaker 1: and some of them get put here on the podcast 128 00:06:44,000 --> 00:06:47,080 Speaker 1: for us to talk about. Just don't ask about Daniel's cats. 129 00:06:47,440 --> 00:06:49,920 Speaker 1: Don't ask too many questions about that, because this whole 130 00:06:49,960 --> 00:06:53,320 Speaker 1: coyote theory is a little suspicious. You know, there's only 131 00:06:53,360 --> 00:06:55,719 Speaker 1: so many answers the universe can provide. There's a quantum 132 00:06:55,760 --> 00:07:00,480 Speaker 1: uncertainty to everything. Sounds like a great criminals there. It 133 00:07:00,480 --> 00:07:03,320 Speaker 1: sounds like even practicing that that's right. On advice of counsel, 134 00:07:03,360 --> 00:07:05,719 Speaker 1: I would like to invoke the Heisenberg on certainty principle. 135 00:07:06,040 --> 00:07:08,080 Speaker 1: Oh that would be a funny courtroom scene. And then 136 00:07:08,240 --> 00:07:11,800 Speaker 1: the lawyer, the opposing articles all drat, they got us, 137 00:07:11,800 --> 00:07:15,360 Speaker 1: he got us. He can't do anything against the Heisenberg defense. Well, 138 00:07:15,400 --> 00:07:17,520 Speaker 1: you have the Boeian attack. Right, I got a little 139 00:07:17,560 --> 00:07:19,840 Speaker 1: too deep for me. Yeah, we'd like to answer listener 140 00:07:19,960 --> 00:07:22,440 Speaker 1: questions here on the podcast at people send in and 141 00:07:22,600 --> 00:07:25,280 Speaker 1: people still send you questions, right, Daniel, Oh, absolutely, I 142 00:07:25,280 --> 00:07:28,240 Speaker 1: get dozens of questions every day, and I enjoy reading 143 00:07:28,280 --> 00:07:31,000 Speaker 1: all of them because they show me what people understand 144 00:07:31,000 --> 00:07:33,440 Speaker 1: and what people don't understand. You know, as a teacher 145 00:07:33,480 --> 00:07:36,760 Speaker 1: and educator, the actual material that I'm teaching isn't always 146 00:07:36,840 --> 00:07:38,720 Speaker 1: terribly exciting to me because I've been doing it for 147 00:07:38,840 --> 00:07:41,680 Speaker 1: decades and decades. What's always a really fun puzzle is 148 00:07:41,720 --> 00:07:44,880 Speaker 1: what confuses people, What got people to some point in 149 00:07:44,920 --> 00:07:48,000 Speaker 1: their understanding that they ask a certain question. The question 150 00:07:48,040 --> 00:07:50,760 Speaker 1: always reveals how they got there and the misstep they took. 151 00:07:50,800 --> 00:07:52,360 Speaker 1: So for me, it's a fun puzzle to go from 152 00:07:52,400 --> 00:07:55,400 Speaker 1: the question to understanding where they went wrong and then 153 00:07:55,480 --> 00:07:59,480 Speaker 1: helping them find a path to clarity. You enjoy seeing 154 00:07:59,520 --> 00:08:05,440 Speaker 1: their confus sort of like a cat plays with its praying. Well, 155 00:08:05,440 --> 00:08:08,760 Speaker 1: that's very confrontational approach, But yeah, I do enjoy seeing 156 00:08:08,760 --> 00:08:12,560 Speaker 1: where people got confused. It helps me sharpen my explanations. Yeah. Cool, Well, 157 00:08:12,600 --> 00:08:15,960 Speaker 1: today we have three awesome questions from listeners. One of 158 00:08:15,960 --> 00:08:19,720 Speaker 1: them is about Schrodinger's cat, another one is about the 159 00:08:19,800 --> 00:08:22,440 Speaker 1: heat death of the universe, and the last one is 160 00:08:22,480 --> 00:08:26,800 Speaker 1: about parallel universes and dark matter and are those two 161 00:08:26,840 --> 00:08:30,240 Speaker 1: things tied together? So we'll jump right into our first question, 162 00:08:30,280 --> 00:08:33,120 Speaker 1: and this one comes from Nils, who's fourteen years old 163 00:08:33,160 --> 00:08:36,120 Speaker 1: and comes from Sweden. Hi, my name is Nieves Pasel. 164 00:08:36,320 --> 00:08:39,000 Speaker 1: I'm a Swedish fourteen year old very interested in both 165 00:08:39,080 --> 00:08:43,040 Speaker 1: physics and philosophy. And my name's Jacob and I'm Niel's dad. 166 00:08:43,320 --> 00:08:46,480 Speaker 1: I'm an ICU nurse currently working on my PhD in 167 00:08:46,600 --> 00:08:50,400 Speaker 1: clinical neuroscience and I share my son's passion for physics 168 00:08:50,400 --> 00:08:53,520 Speaker 1: and philosophy. The other day we had a discussion about 169 00:08:53,520 --> 00:08:56,440 Speaker 1: Schrodinger's cat and we would absolutely love it if you 170 00:08:56,480 --> 00:08:59,840 Speaker 1: guys shed some light on this Shuliess cat is well 171 00:09:00,200 --> 00:09:04,040 Speaker 1: a cat and therefore a quite intelligent and curious creature. 172 00:09:04,600 --> 00:09:08,000 Speaker 1: Couldn't this cat itself be considered to be an observer 173 00:09:08,480 --> 00:09:12,000 Speaker 1: inside the box? And if there is an observer inside 174 00:09:12,040 --> 00:09:16,240 Speaker 1: the box, wouldn't that collapse the quantum uncertainty immediately upon 175 00:09:16,320 --> 00:09:19,240 Speaker 1: being observed by this cat? We would love to hear 176 00:09:19,280 --> 00:09:22,160 Speaker 1: your thoughts outside as well as inside the Box on 177 00:09:22,240 --> 00:09:24,920 Speaker 1: this and thank you for a great podcast. All Right, 178 00:09:24,960 --> 00:09:27,319 Speaker 1: that's an awesome question. I would say that's a pretty 179 00:09:27,320 --> 00:09:32,760 Speaker 1: awesome question. Categorically speaking, it is awesome and especially awesome 180 00:09:32,840 --> 00:09:36,719 Speaker 1: to hear parents and kids talking about science and philosophy together. 181 00:09:36,920 --> 00:09:38,800 Speaker 1: That's wonderful. So thank you very much to all the 182 00:09:38,840 --> 00:09:42,600 Speaker 1: parents out there encouraging your kids to think about science. Yeah. 183 00:09:42,679 --> 00:09:44,920 Speaker 1: We get a lot of kids asking questions with their 184 00:09:44,920 --> 00:09:47,320 Speaker 1: parents sometimes. Yeah, and we hear from people who listen 185 00:09:47,400 --> 00:09:50,040 Speaker 1: to the podcast with their kids and talk about it. 186 00:09:50,080 --> 00:09:52,560 Speaker 1: And while that's a dream come true for me, awesome. Well, 187 00:09:52,559 --> 00:09:54,960 Speaker 1: the question is an interesting one. They're asking us to 188 00:09:55,080 --> 00:09:58,520 Speaker 1: basically sort of explain what Shroudinger's cat is. Yeah, And 189 00:09:58,600 --> 00:10:01,560 Speaker 1: Shroudinger's cat is a really fun thought experiment that puts 190 00:10:01,559 --> 00:10:04,080 Speaker 1: its finger or I guess it's paw or its claw 191 00:10:04,320 --> 00:10:07,520 Speaker 1: on a big problem in quantum mechanics and at the 192 00:10:07,559 --> 00:10:11,360 Speaker 1: intersection of physics and philosophy. Yeah. And their question then 193 00:10:11,400 --> 00:10:14,200 Speaker 1: gets very specifically about the nature of an observer in 194 00:10:14,240 --> 00:10:17,960 Speaker 1: a quantum experiment and what that means and whether cats 195 00:10:17,960 --> 00:10:19,719 Speaker 1: are smart. I guess that's where those part of the 196 00:10:19,800 --> 00:10:23,199 Speaker 1: question that might take up the whole episode though our 197 00:10:23,240 --> 00:10:25,600 Speaker 1: cats as smartest people, and does that solve the quantum 198 00:10:25,600 --> 00:10:28,160 Speaker 1: mechanics measurement problem. In the end, you're gonna have to 199 00:10:28,200 --> 00:10:33,400 Speaker 1: continue this with Katie to talk about cats. But Yees 200 00:10:33,440 --> 00:10:36,960 Speaker 1: steps through Daniel. What is Schrodinger's cat Shortinger's Cat is 201 00:10:36,960 --> 00:10:40,440 Speaker 1: a thought experiment that tries to expose a conflict in 202 00:10:40,640 --> 00:10:43,920 Speaker 1: quantum theory. Right, So, for hundreds of years, we had 203 00:10:43,960 --> 00:10:47,280 Speaker 1: a classical theory of the universe, one that said that 204 00:10:47,320 --> 00:10:50,760 Speaker 1: you know, objects have locations and that they have velocities, 205 00:10:50,800 --> 00:10:53,800 Speaker 1: that there is a reality out there that has infinite 206 00:10:53,800 --> 00:10:56,920 Speaker 1: information and can be knowable, and that an object is 207 00:10:56,920 --> 00:10:59,160 Speaker 1: in one place and in no other place. But then 208 00:10:59,200 --> 00:11:02,199 Speaker 1: we developed quantum theory when we discovered that tiny little 209 00:11:02,240 --> 00:11:05,520 Speaker 1: objects like photons and electrons don't follow those same rules. 210 00:11:05,720 --> 00:11:08,840 Speaker 1: They don't have trajectories where they have a specific location 211 00:11:09,160 --> 00:11:12,640 Speaker 1: and a velocity at every point in time. Instead, they 212 00:11:12,640 --> 00:11:15,800 Speaker 1: can have multiple possibilities. The electron could be here and 213 00:11:15,840 --> 00:11:18,400 Speaker 1: it could also be there at the same time, so 214 00:11:18,400 --> 00:11:22,079 Speaker 1: we call this a superposition of possibilities. So we had 215 00:11:22,200 --> 00:11:25,839 Speaker 1: new quantum rules for quantum stuff, and we had classical 216 00:11:25,920 --> 00:11:29,200 Speaker 1: rules for classical stuff. Because like me and you and 217 00:11:29,400 --> 00:11:32,280 Speaker 1: baseballs and cats don't seem to be able to do 218 00:11:32,360 --> 00:11:35,040 Speaker 1: that thing that quantum objects can do have a possibility 219 00:11:35,040 --> 00:11:37,880 Speaker 1: of being in multiple places at once. So there's this 220 00:11:38,040 --> 00:11:41,200 Speaker 1: weird conflict between the classical rules and the quantum rules 221 00:11:41,200 --> 00:11:44,720 Speaker 1: and where they overlap. So Schroedinger's cat is a thought 222 00:11:44,760 --> 00:11:46,840 Speaker 1: experiment that tries to put its finger on this conflict 223 00:11:46,880 --> 00:11:51,079 Speaker 1: and raise difficult questions. Okay, so then the basic conflict 224 00:11:51,080 --> 00:11:54,480 Speaker 1: here between quantum mechanics and classical physics, it's kind of 225 00:11:54,520 --> 00:11:59,160 Speaker 1: this idea of certainty, right like in classical there's nothing 226 00:11:59,240 --> 00:12:02,360 Speaker 1: uncertain about the baseball flying through the air. You sort 227 00:12:02,400 --> 00:12:04,000 Speaker 1: of know where it's going to land, and when you're 228 00:12:04,000 --> 00:12:05,960 Speaker 1: holding in your hand, it's like it's there, there's no 229 00:12:06,040 --> 00:12:09,480 Speaker 1: question that it's there. But in quantum mechanics there's no 230 00:12:09,559 --> 00:12:11,840 Speaker 1: such thing kind of as certainty, right Like you can't 231 00:12:11,840 --> 00:12:14,800 Speaker 1: hold a photon or an electron in your hand. You 232 00:12:15,240 --> 00:12:18,480 Speaker 1: only can only sort of know where it could be. 233 00:12:18,559 --> 00:12:20,680 Speaker 1: There's a lot of uncertainty about where it actually is. 234 00:12:20,840 --> 00:12:23,880 Speaker 1: That's right, And in the classical case, we can't have 235 00:12:24,040 --> 00:12:27,400 Speaker 1: uncertainty about where the baseball is. But that uncertainty is 236 00:12:27,440 --> 00:12:30,440 Speaker 1: just our lack of knowing the information does exist. The 237 00:12:30,440 --> 00:12:34,200 Speaker 1: baseball is in one particular location, it has one particular velocity, 238 00:12:34,280 --> 00:12:36,959 Speaker 1: we just might not know it. In the quantum case, 239 00:12:37,280 --> 00:12:40,240 Speaker 1: we think that information doesn't actually exist, Like when the 240 00:12:40,320 --> 00:12:42,520 Speaker 1: particle is going through the double slit experiment, it really 241 00:12:42,559 --> 00:12:45,040 Speaker 1: has the possibility to go through both slits at the 242 00:12:45,080 --> 00:12:47,600 Speaker 1: same time, or the electron really could be here and 243 00:12:47,600 --> 00:12:49,920 Speaker 1: it really also could be there, not just that we 244 00:12:50,000 --> 00:12:53,280 Speaker 1: don't know the answer, but that it really isn't determined. 245 00:12:53,360 --> 00:12:55,839 Speaker 1: And then the conflict is what happens when classical stuff 246 00:12:55,840 --> 00:12:59,599 Speaker 1: and quantum stuff interact. Right, when you, as a classical 247 00:12:59,600 --> 00:13:02,240 Speaker 1: object act look for an electron and say, hey, I 248 00:13:02,240 --> 00:13:06,000 Speaker 1: want to know which slit the electron went through. What happens, right, 249 00:13:06,000 --> 00:13:08,440 Speaker 1: and so at that interface is the really awkward part, 250 00:13:08,720 --> 00:13:11,200 Speaker 1: because classical objects can't be in two different states, but 251 00:13:11,280 --> 00:13:14,679 Speaker 1: quantum objects kind of canm Well, I guess, first of all, 252 00:13:14,679 --> 00:13:17,920 Speaker 1: thanks for calling me classy. A lot of people do that. 253 00:13:18,160 --> 00:13:20,600 Speaker 1: So then you were saying that Schrodinger's cat is sort 254 00:13:20,600 --> 00:13:23,600 Speaker 1: of an example or like a thought experiment that doesn't 255 00:13:23,720 --> 00:13:27,120 Speaker 1: it's not there to explain what happens between quantum and 256 00:13:27,200 --> 00:13:30,199 Speaker 1: classical physics. It's more there to like kind of like 257 00:13:30,240 --> 00:13:34,000 Speaker 1: a point a finger to it, or illustrate this conflict. Yeah, 258 00:13:34,040 --> 00:13:35,719 Speaker 1: there are a lot of these great thought experiments in 259 00:13:35,800 --> 00:13:37,920 Speaker 1: quantum mechanics that say, hey, look what you're saying about 260 00:13:37,920 --> 00:13:41,439 Speaker 1: reality is kind of ridiculous. Here's a ridiculous outcome if 261 00:13:41,440 --> 00:13:43,520 Speaker 1: what you're saying is true. And Shortinger's cat is a 262 00:13:43,520 --> 00:13:45,400 Speaker 1: great example of it, and it tries to put its 263 00:13:45,400 --> 00:13:48,040 Speaker 1: finger on this question of like what happens when something 264 00:13:48,040 --> 00:13:51,720 Speaker 1: classical touches something quantum. If you're observing a quantum particle, 265 00:13:51,920 --> 00:13:54,160 Speaker 1: you don't observe it to be in two places at once. 266 00:13:54,440 --> 00:13:57,800 Speaker 1: Somehow it collapses into just one choice. If the electron 267 00:13:57,840 --> 00:14:00,880 Speaker 1: could be spin up or could be spin down when 268 00:14:00,920 --> 00:14:02,800 Speaker 1: you observe it, you just get one or the other. 269 00:14:02,840 --> 00:14:05,640 Speaker 1: How does that work? What is the distinction between a 270 00:14:05,720 --> 00:14:08,400 Speaker 1: quantum object and a classical object? When does the classical 271 00:14:08,400 --> 00:14:12,520 Speaker 1: object know to collapse? So Shortinger thought this was fairly ridiculous, 272 00:14:12,520 --> 00:14:14,320 Speaker 1: So he came up with this example where you have 273 00:14:14,360 --> 00:14:17,480 Speaker 1: a box and inside the box is some quantum process 274 00:14:17,559 --> 00:14:20,760 Speaker 1: like an atom that decays radioactively, and so it might 275 00:14:20,760 --> 00:14:23,800 Speaker 1: decay sooner or might decay later. Based on quantum mechanics. 276 00:14:23,840 --> 00:14:26,760 Speaker 1: But now that's linked to something classical like a cat. 277 00:14:26,840 --> 00:14:28,880 Speaker 1: So when the atom decays, for example, it's linked to 278 00:14:28,880 --> 00:14:32,160 Speaker 1: some mechanism that releases a poison gas and kills the cat. 279 00:14:32,320 --> 00:14:34,720 Speaker 1: So if the atom has decayed, the cat is dead. 280 00:14:34,800 --> 00:14:37,640 Speaker 1: If the atom has not decayed, then the cat is alive. 281 00:14:37,760 --> 00:14:40,680 Speaker 1: And this is a fascinating thought experiment because before you 282 00:14:40,720 --> 00:14:43,000 Speaker 1: look in the box, you can say that the atom 283 00:14:43,080 --> 00:14:46,360 Speaker 1: is in a superposition of having decayed and not having decayed. 284 00:14:46,400 --> 00:14:49,360 Speaker 1: It's not one or the other, has a probability of both, 285 00:14:49,400 --> 00:14:52,200 Speaker 1: which means that the cat in that same sense, has 286 00:14:52,240 --> 00:14:54,640 Speaker 1: a probability of being alive and the probability of being 287 00:14:54,680 --> 00:14:57,480 Speaker 1: dead at the same time. I see. So then the 288 00:14:57,520 --> 00:15:00,200 Speaker 1: cat is inside and it could be alive or it 289 00:15:00,200 --> 00:15:03,640 Speaker 1: could be dead, depending on the outcome of some quantum process. 290 00:15:04,120 --> 00:15:06,920 Speaker 1: But I guess the name question that Neils and Jacob 291 00:15:06,920 --> 00:15:09,440 Speaker 1: were asking is that you know the cat is alive 292 00:15:09,560 --> 00:15:13,960 Speaker 1: and dead only to us from the outside of the box, right, Yeah, 293 00:15:14,000 --> 00:15:16,320 Speaker 1: that's exactly right. And what they're asking is why doesn't 294 00:15:16,320 --> 00:15:19,000 Speaker 1: the cat collapse? The uncertainty, right, if the cat is 295 00:15:19,040 --> 00:15:22,360 Speaker 1: a big, curious creature and a classical object. It can't 296 00:15:22,360 --> 00:15:24,960 Speaker 1: be in multiple states. It can't be dead and alive 297 00:15:25,000 --> 00:15:27,600 Speaker 1: at the same time. Then why doesn't it collapse the 298 00:15:27,600 --> 00:15:31,560 Speaker 1: possibilities and force this atom to either decay or not decay. 299 00:15:31,760 --> 00:15:35,160 Speaker 1: That's essentially their question, right because to us, technically the 300 00:15:35,200 --> 00:15:37,880 Speaker 1: cat is alive and dead according to quantum mechanics. But 301 00:15:37,960 --> 00:15:40,160 Speaker 1: to the cat, the cat knows if it's alive or dead. 302 00:15:40,360 --> 00:15:42,480 Speaker 1: I think that's what they're kind of asking, right, Like, 303 00:15:42,560 --> 00:15:46,440 Speaker 1: the cat is a somewhat conscious creature, and it knows 304 00:15:46,440 --> 00:15:49,200 Speaker 1: whether it's sort of it's observing things, right, it's looking 305 00:15:49,240 --> 00:15:52,120 Speaker 1: at things inside and it's it knows if it's breathing 306 00:15:52,200 --> 00:15:55,920 Speaker 1: or not. So does that mean that the cat definitely 307 00:15:56,120 --> 00:15:59,280 Speaker 1: is alive or dead for the cat, But it's alive 308 00:15:59,360 --> 00:16:01,880 Speaker 1: and dead for us outside of the box. So the 309 00:16:01,960 --> 00:16:06,320 Speaker 1: answer depends on which interpretation or quantum mechanics you prefer, right, 310 00:16:06,360 --> 00:16:08,640 Speaker 1: Because we can't know without opening the box. So you 311 00:16:08,680 --> 00:16:11,360 Speaker 1: can't make a definite statement about what really happens when 312 00:16:11,400 --> 00:16:13,800 Speaker 1: you don't open the box. All we can do is 313 00:16:13,800 --> 00:16:16,000 Speaker 1: say what we think might happen and what it means. 314 00:16:16,080 --> 00:16:18,840 Speaker 1: So we're in the era of philosophy because we don't 315 00:16:18,880 --> 00:16:22,120 Speaker 1: have experiments we can do to distinguish between these various ideas, 316 00:16:22,160 --> 00:16:24,240 Speaker 1: And one of the key problems is that we don't 317 00:16:24,280 --> 00:16:27,240 Speaker 1: have a good distinction between what counts as quantum, what 318 00:16:27,400 --> 00:16:30,400 Speaker 1: is allowed to be described by quantum rules can have uncertainty, 319 00:16:30,600 --> 00:16:33,960 Speaker 1: and what counts as classical. Right, And the Copenhagen interpretation 320 00:16:34,000 --> 00:16:36,760 Speaker 1: is sort of standard interpretation or quantum mechanics that's taught 321 00:16:36,800 --> 00:16:40,880 Speaker 1: to physics majors doesn't define these things. It leaves it uncertain, 322 00:16:41,040 --> 00:16:43,920 Speaker 1: and so there's no clear distinction like when does a 323 00:16:43,960 --> 00:16:46,520 Speaker 1: wave function collapse and when does it not? It's not 324 00:16:46,800 --> 00:16:50,960 Speaker 1: defined or maybe it's only defined or respect to an observer, right, 325 00:16:51,080 --> 00:16:53,960 Speaker 1: what counts is a classical observer that has classical interactions, 326 00:16:53,960 --> 00:16:56,200 Speaker 1: and what counts is a quantum observer that can have 327 00:16:56,280 --> 00:16:59,760 Speaker 1: quantum interactions without collapsing the wave function. That's not to 328 00:17:00,440 --> 00:17:02,440 Speaker 1: I guess. I mean it's like it feels like, you know, 329 00:17:02,680 --> 00:17:05,720 Speaker 1: it definitely collapse for the cat, but for us outside 330 00:17:05,720 --> 00:17:08,720 Speaker 1: of the box where we have like zero information exchange, 331 00:17:09,200 --> 00:17:11,640 Speaker 1: the cat is still alive and dead to us. So 332 00:17:11,680 --> 00:17:15,080 Speaker 1: that's a specific interpretation of quantum mechanics. Carlo Rovelli would 333 00:17:15,119 --> 00:17:17,639 Speaker 1: totally agree with you, because he's a proponent of relational 334 00:17:17,720 --> 00:17:21,199 Speaker 1: quantum mechanics, which says that the collapse is relative, it 335 00:17:21,240 --> 00:17:24,159 Speaker 1: depends on who's doing the observing. Carlo would say that 336 00:17:24,160 --> 00:17:27,080 Speaker 1: the cat collapses the way function, but for us outside 337 00:17:27,119 --> 00:17:30,280 Speaker 1: the box, it's not yet collapsed. That this question of 338 00:17:30,280 --> 00:17:33,280 Speaker 1: whether or not you are collapsed is everything relative between 339 00:17:33,280 --> 00:17:36,480 Speaker 1: an observer and the observed, and not everybody has to 340 00:17:36,520 --> 00:17:38,399 Speaker 1: agree on it. The same way we don't have to 341 00:17:38,440 --> 00:17:42,199 Speaker 1: agree about velocity, because you can have different velocities for 342 00:17:42,280 --> 00:17:46,080 Speaker 1: different objects, he thinks, and relational quantum mechanics suggests that 343 00:17:46,240 --> 00:17:49,199 Speaker 1: collapse is not a universal thing, that you don't have 344 00:17:49,240 --> 00:17:51,560 Speaker 1: to collapse for everybody. You can only collapse for some 345 00:17:51,600 --> 00:17:54,280 Speaker 1: observers and not yet for others. M I see. It 346 00:17:54,359 --> 00:17:58,120 Speaker 1: seems so like philosophy Option one is that it's collapse 347 00:17:58,200 --> 00:18:00,480 Speaker 1: for the cat. The cat knows it's alive or dead, 348 00:18:00,640 --> 00:18:03,800 Speaker 1: but for us it's alive and did that's philosophy option one. 349 00:18:04,119 --> 00:18:08,240 Speaker 1: Philosophy option B or two is that nobody knows. Right, 350 00:18:08,280 --> 00:18:11,320 Speaker 1: it's like it's alive and dead for everybody, even for 351 00:18:11,359 --> 00:18:14,040 Speaker 1: the dead cat. That's right. So relational quantum mechanics would 352 00:18:14,040 --> 00:18:16,720 Speaker 1: say the cat has collapsed the wave function, but we 353 00:18:16,800 --> 00:18:20,360 Speaker 1: have not. Copenhagen sort of orthodox quantum mechanics doesn't even 354 00:18:20,440 --> 00:18:23,840 Speaker 1: really have an agreed upon answer. Essentially, how you define 355 00:18:23,880 --> 00:18:27,080 Speaker 1: the difference between what collapses and what doesn't is something 356 00:18:27,119 --> 00:18:30,080 Speaker 1: people agree on for every experiment. It's like, let's call 357 00:18:30,160 --> 00:18:32,600 Speaker 1: this the observer or let's not call that the observer. 358 00:18:32,800 --> 00:18:34,919 Speaker 1: It's even fuzzier than like not to find. It's like, 359 00:18:34,960 --> 00:18:37,080 Speaker 1: you know, let's just have a consensus for everything and 360 00:18:37,119 --> 00:18:39,960 Speaker 1: define where this cut is between quantum and classical. And 361 00:18:40,240 --> 00:18:43,880 Speaker 1: so even people who believe in Copenhagen might disagree about 362 00:18:43,920 --> 00:18:46,200 Speaker 1: how to interpret this experiment. Some might say, look, the 363 00:18:46,359 --> 00:18:48,919 Speaker 1: cat is a classical object. It collapses the way of function, 364 00:18:49,000 --> 00:18:51,399 Speaker 1: there's no question. And other people might say, I just 365 00:18:51,480 --> 00:18:53,600 Speaker 1: view the whole box is a quantum object, and the 366 00:18:53,680 --> 00:18:55,960 Speaker 1: cat is just like a big quantum object and it's 367 00:18:55,960 --> 00:18:58,560 Speaker 1: not yet collapsed until we open it. So even people 368 00:18:58,600 --> 00:19:01,800 Speaker 1: who believe in Copenhagen interpret, I think, would disagree about 369 00:19:01,800 --> 00:19:04,120 Speaker 1: what's happening in this experiment. Well, I feel like maybe 370 00:19:04,160 --> 00:19:07,320 Speaker 1: there's an option see for philosophy in the philosophy here, 371 00:19:07,440 --> 00:19:10,560 Speaker 1: which is kind of this idea of the quantum multiverse, right, 372 00:19:10,720 --> 00:19:14,000 Speaker 1: like maybe nothing ever collapses at all, Like maybe there's 373 00:19:14,000 --> 00:19:16,919 Speaker 1: no such thing as collapse, and things just kind of 374 00:19:17,000 --> 00:19:20,040 Speaker 1: stay uncertain for everyone forever, and you get all these 375 00:19:20,040 --> 00:19:24,080 Speaker 1: different multiple universes, right, like maybe the cat is alive 376 00:19:24,119 --> 00:19:27,439 Speaker 1: and dead inside the box, and we us outside of 377 00:19:27,440 --> 00:19:30,280 Speaker 1: the box. There are two universes, one in which if 378 00:19:30,320 --> 00:19:32,080 Speaker 1: I open the box, it's going to be alive, and 379 00:19:32,280 --> 00:19:34,080 Speaker 1: one which if I open the box is going to 380 00:19:34,119 --> 00:19:35,800 Speaker 1: be dead, and so we are also kind of in 381 00:19:35,880 --> 00:19:39,080 Speaker 1: a state of superposition. Yeah. Absolutely, And that's the many 382 00:19:39,200 --> 00:19:42,200 Speaker 1: worlds interpretation of quantum mechanics. So Sean Carroll would probably 383 00:19:42,240 --> 00:19:44,600 Speaker 1: agree with you. The question there is when does the 384 00:19:44,680 --> 00:19:47,440 Speaker 1: universe split. Does it split when the cat is looking 385 00:19:47,440 --> 00:19:49,560 Speaker 1: at the atom with a Harry eyeball wondering if it's 386 00:19:49,560 --> 00:19:51,720 Speaker 1: about to kill it, or when you open the box 387 00:19:51,760 --> 00:19:53,960 Speaker 1: and observe it. But you're right, in this many worlds view, 388 00:19:54,000 --> 00:19:57,040 Speaker 1: there is no collapse. It says. Collapse is nonsense. It's 389 00:19:57,119 --> 00:19:59,760 Speaker 1: not consistent with the Shortener equation, it's not consistent with 390 00:19:59,760 --> 00:20:02,440 Speaker 1: every anything we know about quantum mechanics. That information is 391 00:20:02,480 --> 00:20:06,920 Speaker 1: preserved because it's collapsed, like violates the conservation of quantum information. 392 00:20:06,960 --> 00:20:09,520 Speaker 1: It makes no sense mathematically, and so they say, let's 393 00:20:09,520 --> 00:20:12,159 Speaker 1: just have the shorting your equation dictate everything. And what 394 00:20:12,200 --> 00:20:14,359 Speaker 1: happens when you observe something as the wave function gets 395 00:20:14,359 --> 00:20:17,080 Speaker 1: two branches, one for each slice of them multiverse, and 396 00:20:17,160 --> 00:20:19,000 Speaker 1: now you're in one of them, so you only see 397 00:20:19,040 --> 00:20:20,840 Speaker 1: one and not the other. I've always found that a 398 00:20:20,880 --> 00:20:23,240 Speaker 1: little bit unsatisfying because it doesn't really answer the question 399 00:20:23,280 --> 00:20:25,560 Speaker 1: of why you're in one of those branches and not 400 00:20:25,600 --> 00:20:28,560 Speaker 1: the other branches. You're supposed to believe those other branches 401 00:20:28,560 --> 00:20:31,160 Speaker 1: are at the same philosophical level as yours, even though 402 00:20:31,400 --> 00:20:35,160 Speaker 1: you're in this one. But mathematically it's a very pretty view, 403 00:20:36,040 --> 00:20:38,760 Speaker 1: all right. Then what's the answer for Niels and Jacob then, 404 00:20:38,880 --> 00:20:42,320 Speaker 1: is that there's a superposition of answers here and they're 405 00:20:42,359 --> 00:20:45,920 Speaker 1: all true and false at the same time. Yeah. Absolutely, 406 00:20:45,960 --> 00:20:48,159 Speaker 1: And there's even philosophy option D, which is that there 407 00:20:48,240 --> 00:20:51,840 Speaker 1: is no randomness. Right. Boemian mechanics believes the quantum mechanics 408 00:20:51,880 --> 00:20:55,159 Speaker 1: isn't even random at all. It's deterministic, and either the 409 00:20:55,200 --> 00:20:57,040 Speaker 1: cat is dead or it is alive, and it was 410 00:20:57,080 --> 00:21:00,400 Speaker 1: determined before anything happened that went into the box. Maybe 411 00:21:00,440 --> 00:21:03,080 Speaker 1: even by the Big Bang. So the answer for Neils 412 00:21:03,080 --> 00:21:04,919 Speaker 1: and Jacob is that this is not something we're going 413 00:21:05,000 --> 00:21:07,520 Speaker 1: to answer today on the podcast. Nobody knows where it 414 00:21:07,520 --> 00:21:11,000 Speaker 1: really happens. None of our views of quantum mechanics really 415 00:21:11,040 --> 00:21:14,399 Speaker 1: answered this question satisfactorily. No, no, no, Daniel, let's just 416 00:21:14,400 --> 00:21:17,200 Speaker 1: collapse the question itself and let's just pick an answer, 417 00:21:17,240 --> 00:21:18,840 Speaker 1: and that's the universe that we live in, and a 418 00:21:18,920 --> 00:21:20,440 Speaker 1: quarter of the time will be right. Well, then I 419 00:21:20,480 --> 00:21:21,960 Speaker 1: want the cat to be alive so that it can 420 00:21:21,960 --> 00:21:27,560 Speaker 1: survive and then later get eaten by coyotes. I don't 421 00:21:27,560 --> 00:21:30,119 Speaker 1: know what's worse to die in a physic experiment or 422 00:21:30,119 --> 00:21:32,479 Speaker 1: to be eaten by coyotes. Well, you know, my cats 423 00:21:32,520 --> 00:21:34,679 Speaker 1: had the option to be stuck in the box of 424 00:21:34,760 --> 00:21:38,160 Speaker 1: my home or to live outside and enjoy the outdoor 425 00:21:38,200 --> 00:21:40,320 Speaker 1: life of a cat, and that's what they chose, and 426 00:21:40,440 --> 00:21:43,359 Speaker 1: they paid the price. Wow, now we're getting into free 427 00:21:43,359 --> 00:21:46,159 Speaker 1: will and feline free will. We're gonna eat the not 428 00:21:46,240 --> 00:21:48,560 Speaker 1: just katies, some kind of philosopher in here too. And 429 00:21:48,640 --> 00:21:50,960 Speaker 1: for those of you worried about outdoor birds, we also 430 00:21:51,000 --> 00:21:53,240 Speaker 1: worried about them, and we put very loud bells on 431 00:21:53,280 --> 00:21:55,600 Speaker 1: the cats. Though that might not have been helpful when 432 00:21:55,600 --> 00:21:57,679 Speaker 1: it came to the coyotes. All right, well, I think 433 00:21:57,720 --> 00:22:00,280 Speaker 1: that's the as for Neils and Jacob, which is at 434 00:22:00,960 --> 00:22:04,200 Speaker 1: it kind of depends and the very nature, the philosophical 435 00:22:04,280 --> 00:22:06,480 Speaker 1: nature of the universe. It could be that they're right, 436 00:22:06,560 --> 00:22:09,000 Speaker 1: that the cat collapses inside of the box and we 437 00:22:09,119 --> 00:22:10,840 Speaker 1: just have to open it to find out what happened. 438 00:22:11,000 --> 00:22:13,320 Speaker 1: It could be that the cat is alive and dead 439 00:22:13,359 --> 00:22:16,040 Speaker 1: inside of the box and we just don't know it. 440 00:22:16,440 --> 00:22:18,159 Speaker 1: And it could be that we're all in some kind 441 00:22:18,200 --> 00:22:20,960 Speaker 1: of multiverse where every decision gets played out in a 442 00:22:21,000 --> 00:22:23,360 Speaker 1: whole different plane of existence. That's right. If you want 443 00:22:23,359 --> 00:22:25,920 Speaker 1: to go further down the philosophical rabbit hole, I recommend 444 00:22:25,960 --> 00:22:29,159 Speaker 1: you read about Vigner's friends experiment, where you have people 445 00:22:29,280 --> 00:22:32,560 Speaker 1: inside the box, and then the whole experiment inside another box, 446 00:22:32,600 --> 00:22:36,640 Speaker 1: and then that whole experiment inside another box, etc. Etc. Oh, man, 447 00:22:36,640 --> 00:22:41,040 Speaker 1: now you're gonna experiment with rabbits and humans. Let's not 448 00:22:41,119 --> 00:22:43,679 Speaker 1: open that box. All right, Well, thank you Nielson Jacob 449 00:22:43,720 --> 00:22:46,000 Speaker 1: for this question. Let's get to some of our other 450 00:22:46,080 --> 00:22:48,959 Speaker 1: questions about the heat death of the universe and also 451 00:22:49,680 --> 00:22:53,119 Speaker 1: dark matter and parallel universes. But first, let's take a 452 00:22:53,200 --> 00:23:08,520 Speaker 1: quick break. All right. We are answering listener questions here 453 00:23:08,520 --> 00:23:12,920 Speaker 1: today from curious listeners who have amazing questions. One question 454 00:23:13,119 --> 00:23:15,639 Speaker 1: we didn't quite answer in the last segment, Daniel was 455 00:23:15,760 --> 00:23:19,000 Speaker 1: about Truedinger's cat, which is, what's the origin of Trudinger's cat? 456 00:23:19,040 --> 00:23:23,520 Speaker 1: The Truedinger really have a cat? Schroedinger is actually quite 457 00:23:23,520 --> 00:23:27,280 Speaker 1: a colorful figure, and now a controversial one. It's not 458 00:23:27,400 --> 00:23:29,399 Speaker 1: really that nice a dude. It turns out the kind 459 00:23:29,440 --> 00:23:31,119 Speaker 1: of things he got into is not the kind of 460 00:23:31,119 --> 00:23:33,679 Speaker 1: things we should dig into on a family friendly podcast. 461 00:23:33,800 --> 00:23:36,000 Speaker 1: So I don't know what that says about the likelihood 462 00:23:36,000 --> 00:23:37,680 Speaker 1: that he was nice to his cat. But I guess 463 00:23:37,680 --> 00:23:39,760 Speaker 1: maybe what I'm asking is like, did he come up 464 00:23:39,760 --> 00:23:42,560 Speaker 1: with this example of the Schulinger's cat maybe based on 465 00:23:42,600 --> 00:23:44,360 Speaker 1: a cat you may or may not have had, or 466 00:23:44,400 --> 00:23:46,520 Speaker 1: did somebody else come up with the cat in the 467 00:23:46,600 --> 00:23:49,879 Speaker 1: box idea and just assigned it the Schroedinger. Oh no, 468 00:23:49,920 --> 00:23:53,080 Speaker 1: it was very much Schroedinger's example. Yes, it is his 469 00:23:53,359 --> 00:23:56,399 Speaker 1: idea of the cat in the box. M interesting, and 470 00:23:56,440 --> 00:23:59,880 Speaker 1: he naended my cat. He's a here's an experiment, it's 471 00:24:00,240 --> 00:24:02,080 Speaker 1: my cat. I don't know, maybe he hated cats, and 472 00:24:02,119 --> 00:24:03,760 Speaker 1: that's why I put a cat in the boxing's trying 473 00:24:03,760 --> 00:24:06,800 Speaker 1: to protect theoretical rabbits and theoretical dogs. I don't know, 474 00:24:06,960 --> 00:24:10,040 Speaker 1: oh Man physicists or I just get to a second 475 00:24:10,080 --> 00:24:13,320 Speaker 1: question here, and this one comes from Mattis. Hello, Daniel, 476 00:24:13,359 --> 00:24:15,960 Speaker 1: and I have a question for the podcast. If all 477 00:24:16,040 --> 00:24:18,600 Speaker 1: energy a movement stops at the heat that of the universe, 478 00:24:18,800 --> 00:24:22,080 Speaker 1: which things still be moving at a quantum level? Thanks 479 00:24:22,080 --> 00:24:24,719 Speaker 1: for answering, all right, nice and brief. I like that 480 00:24:25,960 --> 00:24:29,000 Speaker 1: He's like, here's my question. Bam. He's got that very 481 00:24:29,000 --> 00:24:32,119 Speaker 1: efficient Dutch attitude. He probably recorded this wall he was 482 00:24:32,119 --> 00:24:36,119 Speaker 1: on his bicycle writing past some windmills, probably next to 483 00:24:36,160 --> 00:24:39,800 Speaker 1: assume tulips eating at m cheese. I've seen the Dutch 484 00:24:39,880 --> 00:24:42,479 Speaker 1: folks do things on bikes I've never imagined, like they 485 00:24:42,520 --> 00:24:45,000 Speaker 1: bike away from the train station with a rolling suitcase 486 00:24:45,119 --> 00:24:48,880 Speaker 1: next to them on the bicycle. It's amazing. Nice. Well, 487 00:24:48,960 --> 00:24:52,040 Speaker 1: Mattie's question here is about the heat death of the universe, 488 00:24:52,400 --> 00:24:54,480 Speaker 1: and I guess what it really means and whether or 489 00:24:54,520 --> 00:24:57,280 Speaker 1: not quantum things still apply at the end of the 490 00:24:57,359 --> 00:24:59,600 Speaker 1: universe if it dies by heat death. Yeah, this is 491 00:24:59,640 --> 00:25:01,560 Speaker 1: a great question and one that I'm very hambid I 492 00:25:01,600 --> 00:25:04,240 Speaker 1: talked about on the podcast today because there's a common 493 00:25:04,280 --> 00:25:07,520 Speaker 1: misconception about what the heat death of the universe is. 494 00:25:07,720 --> 00:25:09,680 Speaker 1: The heat death of the universe does not mean when 495 00:25:09,720 --> 00:25:13,639 Speaker 1: everything is zero temperature and totally frozen at absolute zero. 496 00:25:14,080 --> 00:25:16,640 Speaker 1: The heat death of the universe instead means when all 497 00:25:16,640 --> 00:25:20,600 Speaker 1: the heat is smoothed out, when everything is the same temperature, 498 00:25:20,720 --> 00:25:23,840 Speaker 1: when there's no more energy flow in the universe, basically 499 00:25:23,840 --> 00:25:27,840 Speaker 1: when everything is in perfect thermodynamic equilibrium. Let's take a 500 00:25:27,840 --> 00:25:30,119 Speaker 1: step back here and maybe talk about what is the 501 00:25:30,119 --> 00:25:31,960 Speaker 1: heat death of the universe. It's it's kind of an 502 00:25:31,960 --> 00:25:35,520 Speaker 1: idea about how the universe might end, right, and it 503 00:25:35,520 --> 00:25:38,120 Speaker 1: comes from this idea that if the universe keeps expanding 504 00:25:38,119 --> 00:25:40,840 Speaker 1: and expanding and further and further, eventually it's going to 505 00:25:40,880 --> 00:25:43,000 Speaker 1: get to a point which, you know, some people might 506 00:25:43,000 --> 00:25:44,760 Speaker 1: call it the end of the universe. Some people might 507 00:25:44,760 --> 00:25:47,399 Speaker 1: just call it like the universe getting stuck, but they 508 00:25:47,400 --> 00:25:49,800 Speaker 1: call it the heat death of the universe, even though 509 00:25:49,840 --> 00:25:53,719 Speaker 1: it has nothing to do well, it won't be very hot, 510 00:25:53,960 --> 00:25:55,920 Speaker 1: but it does have something to do with heat because 511 00:25:55,920 --> 00:25:59,320 Speaker 1: it is a thermodynamic analysis and it's basically just trying 512 00:25:59,320 --> 00:26:01,480 Speaker 1: to predict the future of the universe. You're right, because 513 00:26:01,520 --> 00:26:04,760 Speaker 1: something we notice in the universe is that energy likes 514 00:26:04,800 --> 00:26:06,960 Speaker 1: to even itself out. You have a hot spot on 515 00:26:07,000 --> 00:26:09,480 Speaker 1: your counter, that energy is going to bleed out to 516 00:26:09,520 --> 00:26:11,280 Speaker 1: the rest of your counter, and it's going to even out. 517 00:26:11,359 --> 00:26:12,920 Speaker 1: You put an ice cube in a hot cup of coffee, 518 00:26:12,960 --> 00:26:14,600 Speaker 1: you come back five minutes later, you don't still have 519 00:26:14,640 --> 00:26:17,040 Speaker 1: an ice cube. You don't have half the coffee being 520 00:26:17,080 --> 00:26:19,119 Speaker 1: hot and half of it being cold. You have it 521 00:26:19,160 --> 00:26:22,000 Speaker 1: all about the same temperature. And so what we notice 522 00:26:22,040 --> 00:26:25,000 Speaker 1: in the universe is that things tend to basically smooth 523 00:26:25,080 --> 00:26:28,320 Speaker 1: themselves out in terms of temperature and in terms of energy. 524 00:26:28,800 --> 00:26:31,520 Speaker 1: And so if you extrapolate that really far in the future, 525 00:26:31,680 --> 00:26:34,080 Speaker 1: then you end up with universe that's sort of smooth 526 00:26:34,359 --> 00:26:37,080 Speaker 1: that way, where there's no hot spots and no cold spots. 527 00:26:37,119 --> 00:26:39,000 Speaker 1: And that would be a bummer because we kind of 528 00:26:39,040 --> 00:26:41,879 Speaker 1: rely on energy flow to do most of the things 529 00:26:41,920 --> 00:26:44,359 Speaker 1: we do, like living. I see. So it's kind of 530 00:26:44,400 --> 00:26:46,840 Speaker 1: the idea that if you just leave the universe out 531 00:26:47,080 --> 00:26:50,919 Speaker 1: on your coffee table, eventually, right now it has a 532 00:26:50,920 --> 00:26:52,960 Speaker 1: lot of hot spots and cold spots. Right there's the 533 00:26:53,000 --> 00:26:55,159 Speaker 1: Sun that's really hot. There's the center of the galaxy 534 00:26:55,240 --> 00:26:57,639 Speaker 1: that's really hot, and some pots spots that are really cold. 535 00:26:57,760 --> 00:26:59,639 Speaker 1: Like if you leave your universe out on the table 536 00:26:59,760 --> 00:27:03,240 Speaker 1: for or you know, a few trillions of years, eventually 537 00:27:03,280 --> 00:27:05,840 Speaker 1: it's all going to smooth out and just be like 538 00:27:05,880 --> 00:27:08,720 Speaker 1: a room temperature universe. Yeah, exactly. It's sort of like 539 00:27:08,720 --> 00:27:11,920 Speaker 1: the battery runs out on the universe, you know, batteries 540 00:27:11,960 --> 00:27:14,640 Speaker 1: and any other sort of technique we have to extract 541 00:27:14,760 --> 00:27:17,919 Speaker 1: energy from the universe relies on energy flowing, right, maybe 542 00:27:18,119 --> 00:27:21,560 Speaker 1: water is flowing downhill, or steam is rising to turn 543 00:27:21,600 --> 00:27:24,879 Speaker 1: a turbine or something that relies on energy flows, and 544 00:27:24,920 --> 00:27:26,960 Speaker 1: so if the energy is not flowing anymore, you can't 545 00:27:27,000 --> 00:27:29,760 Speaker 1: extract any more energy from the universe. So it's sort 546 00:27:29,800 --> 00:27:31,840 Speaker 1: of like if you put ice in your drink and 547 00:27:31,920 --> 00:27:34,399 Speaker 1: you come back later, it's all the same temperature. You 548 00:27:34,400 --> 00:27:37,760 Speaker 1: can't do anything with that because there's no energy moving around. 549 00:27:37,760 --> 00:27:41,480 Speaker 1: Even if there still is energy inside that drink, there's 550 00:27:41,520 --> 00:27:44,840 Speaker 1: no useful energy. So there's a distinction there between useful 551 00:27:44,960 --> 00:27:48,879 Speaker 1: energy and actual energy temperature in the universe. You can 552 00:27:48,920 --> 00:27:51,080 Speaker 1: get to a place where the universe is totally smooth, 553 00:27:51,160 --> 00:27:53,760 Speaker 1: everything is the same temperature, so you can't do anything 554 00:27:54,080 --> 00:27:57,360 Speaker 1: without that temperature actually being zero, right, And maybe just 555 00:27:57,400 --> 00:28:00,360 Speaker 1: for our listeners, maybe paint a picture of how that happens. 556 00:28:00,400 --> 00:28:02,560 Speaker 1: Like right now, we have hot spots, like, for example, 557 00:28:02,600 --> 00:28:04,680 Speaker 1: the Sun or like the core of the Earth. It's 558 00:28:04,720 --> 00:28:06,640 Speaker 1: pretty hot. But I guess I should just like run 559 00:28:06,720 --> 00:28:09,879 Speaker 1: the clock forward to what happens. I guess eventually the 560 00:28:09,920 --> 00:28:13,399 Speaker 1: Sun will go out, they'll run out of fuel, and 561 00:28:13,400 --> 00:28:15,240 Speaker 1: then it'll be sit there hot and then but then 562 00:28:15,240 --> 00:28:18,120 Speaker 1: eventually all that heat will sort of radiate out into 563 00:28:18,160 --> 00:28:21,080 Speaker 1: the universe, right, and it will just get cold. That's right. 564 00:28:21,080 --> 00:28:23,240 Speaker 1: There's a lot of energy stored in the Sun, but 565 00:28:23,320 --> 00:28:25,280 Speaker 1: that energy is not going to be stored there forever. 566 00:28:25,680 --> 00:28:27,920 Speaker 1: It's getting released. That's what the Sun is doing. It's 567 00:28:27,920 --> 00:28:30,600 Speaker 1: blasting its energy out into the rest of the universe. 568 00:28:30,920 --> 00:28:33,000 Speaker 1: But the Sun will not last forever, and so that 569 00:28:33,160 --> 00:28:35,520 Speaker 1: energy will fly out in terms of photons and get 570 00:28:35,560 --> 00:28:38,160 Speaker 1: absorbed by other stuff. But energy likes to move around. 571 00:28:38,280 --> 00:28:40,720 Speaker 1: If those photons heat something up, then that thing will 572 00:28:40,760 --> 00:28:43,800 Speaker 1: also emit photons on its own. It will emit black 573 00:28:43,800 --> 00:28:46,400 Speaker 1: body radiation to sort of heat up the stuff around it. 574 00:28:46,640 --> 00:28:48,680 Speaker 1: So the energy in the whole universe just sort of 575 00:28:48,720 --> 00:28:52,560 Speaker 1: spreads out. And this is a basic rule of thermodynamics. 576 00:28:52,560 --> 00:28:55,760 Speaker 1: It's because entropy has to increase in the universe, and 577 00:28:55,760 --> 00:28:58,520 Speaker 1: the way to increase entropy is to spread the energy 578 00:28:58,600 --> 00:29:01,600 Speaker 1: out because it increases like the number of possible micro 579 00:29:01,720 --> 00:29:04,520 Speaker 1: states you can have going on inside the thing, like 580 00:29:04,560 --> 00:29:06,480 Speaker 1: for example, the Earth, Like the Earth is pretty warm 581 00:29:06,480 --> 00:29:08,880 Speaker 1: at the center now, but eventually, over time it's just 582 00:29:08,920 --> 00:29:11,800 Speaker 1: going to turn into a cold rock, and all that 583 00:29:11,920 --> 00:29:13,800 Speaker 1: energy is going to go out into space and maybe 584 00:29:13,880 --> 00:29:16,000 Speaker 1: hit other things. But eventually those think everything's going to 585 00:29:16,160 --> 00:29:18,800 Speaker 1: kind of reach room temperature. Yeah, not quite room temperature, 586 00:29:18,960 --> 00:29:21,960 Speaker 1: like comfortable temperature for us, but sort of like universe 587 00:29:22,040 --> 00:29:24,160 Speaker 1: room temperature, which is going to be like a couple 588 00:29:24,200 --> 00:29:27,000 Speaker 1: degrees above absolute zero. And you might wonder, like, how 589 00:29:27,080 --> 00:29:29,080 Speaker 1: is the Earth going to lose that energy? It's not 590 00:29:29,160 --> 00:29:32,800 Speaker 1: glowing like the sun, But actually it is right, everything 591 00:29:33,040 --> 00:29:35,880 Speaker 1: is glowing. The Earth actually is glowing, just not in 592 00:29:35,920 --> 00:29:38,080 Speaker 1: the visible light. If you looked at the Earth with 593 00:29:38,120 --> 00:29:40,760 Speaker 1: an infrared camera, you would see it glowing just in 594 00:29:40,760 --> 00:29:45,120 Speaker 1: a spectrum that's too long wavelength for our eyeballs to see. 595 00:29:45,240 --> 00:29:47,560 Speaker 1: So we can see other planets out there glowing with 596 00:29:47,600 --> 00:29:50,720 Speaker 1: a James Web infrared telescope. That's one way that they 597 00:29:50,760 --> 00:29:53,840 Speaker 1: can discover exoplanets, for example. So everything out there in 598 00:29:53,880 --> 00:29:56,800 Speaker 1: the universe is shedding its energy, and as time goes 599 00:29:56,800 --> 00:29:59,400 Speaker 1: on and energy tends to smooth out more and more 600 00:29:59,440 --> 00:30:02,280 Speaker 1: and more, and the heat death is just extrapolate that 601 00:30:02,440 --> 00:30:05,280 Speaker 1: really really far out in the future where all the 602 00:30:05,400 --> 00:30:08,280 Speaker 1: energy has managed to leak out and spread around. Yeah, 603 00:30:08,360 --> 00:30:10,360 Speaker 1: so then now you kind of have to imagine the 604 00:30:10,400 --> 00:30:13,400 Speaker 1: future of the universe where you know, the Earth is cold, 605 00:30:13,560 --> 00:30:16,400 Speaker 1: the Sun has gone out and it's cold. Everything's cold. 606 00:30:16,440 --> 00:30:19,560 Speaker 1: All the stars in the entire universe are cold, and 607 00:30:19,680 --> 00:30:22,560 Speaker 1: now maybe even like pulverized, and it's all sort of 608 00:30:22,600 --> 00:30:25,880 Speaker 1: this kind of basically super cold place. There's no energy 609 00:30:26,280 --> 00:30:29,040 Speaker 1: stored in any one place for there to spark a 610 00:30:29,080 --> 00:30:31,360 Speaker 1: new sun for example. Right, that's right, But even a 611 00:30:31,440 --> 00:30:34,200 Speaker 1: cold Earth does have some energy stored inside of it. 612 00:30:34,520 --> 00:30:36,640 Speaker 1: So you've got to go even deeper into the future 613 00:30:37,000 --> 00:30:40,600 Speaker 1: when everything falls into the supermassive black holes at the 614 00:30:40,600 --> 00:30:43,880 Speaker 1: hearts of galaxies and then is radiated back out by 615 00:30:43,920 --> 00:30:47,320 Speaker 1: a Hawking radiation. So now everything has basically been converted 616 00:30:47,320 --> 00:30:49,880 Speaker 1: to whatever is inside a black hole and then radiated 617 00:30:49,920 --> 00:30:53,120 Speaker 1: back out sort of like fed through these cosmic shredder. 618 00:30:53,320 --> 00:30:55,440 Speaker 1: Now the whole universe is just sort of bathed in 619 00:30:55,560 --> 00:30:59,080 Speaker 1: Hawking radiation, so there's no like hard lumps of cold 620 00:30:59,160 --> 00:31:01,640 Speaker 1: Earth or any thing I see. Eventually, even the cold 621 00:31:01,640 --> 00:31:04,200 Speaker 1: Earth and the cold Sun will collapse, right because orbits 622 00:31:04,240 --> 00:31:07,320 Speaker 1: don't last forever. Eventually everything's going to collapse, the galaxy 623 00:31:07,320 --> 00:31:09,560 Speaker 1: of cold stars and planets, it's all going to collapse 624 00:31:09,560 --> 00:31:11,400 Speaker 1: into a black hole. But then you're saying the black 625 00:31:11,440 --> 00:31:15,280 Speaker 1: hole evaporates at some point, even if it's super gigantic massive, 626 00:31:15,720 --> 00:31:19,560 Speaker 1: it's going to evaporate eventually right into what light. Well, 627 00:31:19,560 --> 00:31:21,760 Speaker 1: Hawking radiation can be light, but it can also be 628 00:31:21,800 --> 00:31:24,800 Speaker 1: other particles. It's really fascinating because it's sort of democratic, 629 00:31:24,920 --> 00:31:27,880 Speaker 1: meaning it can create any kind of particle that's out there, 630 00:31:28,320 --> 00:31:30,080 Speaker 1: which is a really awesome kind of tool because you 631 00:31:30,120 --> 00:31:32,000 Speaker 1: want to study like what particles are out there in 632 00:31:32,000 --> 00:31:34,280 Speaker 1: the universe. You can just go like observe the edge 633 00:31:34,320 --> 00:31:36,360 Speaker 1: of a black hole and it'll basically show you all 634 00:31:36,400 --> 00:31:39,880 Speaker 1: of nature's menu, which is amazing. Though that's technically quite 635 00:31:39,920 --> 00:31:42,840 Speaker 1: difficult to do, and we've never actually observed hawking radiation. 636 00:31:42,920 --> 00:31:45,640 Speaker 1: But in theory, all black holes, even the really really 637 00:31:45,680 --> 00:31:49,120 Speaker 1: big ones, do emit hawking radiation because they have an entropy, 638 00:31:49,160 --> 00:31:51,760 Speaker 1: they have a temperature, and everything in the universe with 639 00:31:51,840 --> 00:31:55,560 Speaker 1: a temperature does emit some kind of radiation. And so 640 00:31:55,600 --> 00:31:58,440 Speaker 1: then if you keep fast forwarding, these black holes will 641 00:31:58,520 --> 00:32:01,520 Speaker 1: evaporate out, and so now universe is what just filled 642 00:32:01,560 --> 00:32:07,080 Speaker 1: with flying photons and tiny matter particles. And the idea 643 00:32:07,280 --> 00:32:09,800 Speaker 1: is that everything is perfectly spread out, so there's no 644 00:32:09,960 --> 00:32:13,600 Speaker 1: like hot clumps of matter, there's no overdensities, there's no 645 00:32:13,760 --> 00:32:16,720 Speaker 1: under densities. This is sort of like the very deep future. 646 00:32:16,760 --> 00:32:19,920 Speaker 1: And we're not talking about like twenty fifty or five 647 00:32:19,920 --> 00:32:22,240 Speaker 1: thousand years from now, or ten million years from now 648 00:32:22,320 --> 00:32:25,920 Speaker 1: or ten trillion years from now. We're talking so far 649 00:32:26,040 --> 00:32:28,160 Speaker 1: deep in the future it's hard to even really wrap 650 00:32:28,200 --> 00:32:31,360 Speaker 1: your mind around the time we're talking about. It's like 651 00:32:31,560 --> 00:32:34,920 Speaker 1: ten to the one hundred years in the future. But 652 00:32:34,960 --> 00:32:36,720 Speaker 1: I guess maybe a question is if black holes do 653 00:32:36,760 --> 00:32:40,280 Speaker 1: evaporate into matter particles, when of these matter particles flying 654 00:32:40,320 --> 00:32:43,800 Speaker 1: around eventually like stick together or be attracted to each 655 00:32:43,800 --> 00:32:46,160 Speaker 1: other by gravity, and then then you get more stuff, 656 00:32:46,200 --> 00:32:50,160 Speaker 1: and then suddenly you have like new planets and new stars. 657 00:32:50,480 --> 00:32:52,920 Speaker 1: So this is really the hard I think of Matthias's question, Right, 658 00:32:52,920 --> 00:32:54,920 Speaker 1: it's like, what's going on with that stuff? Do you 659 00:32:54,960 --> 00:32:58,040 Speaker 1: still have quantum frothiness or not? And you still do 660 00:32:58,120 --> 00:33:00,280 Speaker 1: have particles and they are still flying around own and 661 00:33:00,320 --> 00:33:03,400 Speaker 1: photons will still interact with electrons, right, Just like when 662 00:33:03,440 --> 00:33:06,600 Speaker 1: your drink cools down to an even temperature because you 663 00:33:06,640 --> 00:33:09,200 Speaker 1: put ice in it, you still have particles in that 664 00:33:09,320 --> 00:33:11,440 Speaker 1: drink that are moving around. There's still motion, there's still 665 00:33:11,480 --> 00:33:14,400 Speaker 1: interactions that are happening. It's not like everything is stuck 666 00:33:14,440 --> 00:33:17,280 Speaker 1: and frozen. It's just that everything is smooth and even 667 00:33:17,560 --> 00:33:20,160 Speaker 1: so nothing can get started, Like gravity in order to 668 00:33:20,160 --> 00:33:23,360 Speaker 1: get started requires some overdensity. If you had a perfectly 669 00:33:23,360 --> 00:33:27,600 Speaker 1: smooth universe, gravity couldn't do anything. Gravity can accentuate lumps, 670 00:33:27,680 --> 00:33:31,040 Speaker 1: but it can't start lumps. Right, Well, you're assuming you 671 00:33:31,520 --> 00:33:34,360 Speaker 1: start with like a universe where every particle standing still 672 00:33:34,360 --> 00:33:38,120 Speaker 1: and it's a perfectly equal distance from all other particles. 673 00:33:38,200 --> 00:33:40,200 Speaker 1: But that's not kind of like it. It seems very 674 00:33:40,240 --> 00:33:42,680 Speaker 1: unlikely that we'll get to that point, you know what 675 00:33:42,680 --> 00:33:44,840 Speaker 1: I mean? Like, if there are black holes evaporating, wouldn't 676 00:33:44,880 --> 00:33:47,400 Speaker 1: they have you know, wouldn't the particles have some velocity 677 00:33:47,480 --> 00:33:49,480 Speaker 1: coming out of the black hole, and then wouldn't those 678 00:33:49,560 --> 00:33:52,440 Speaker 1: mixed with other things, and you know, wouldn't gravity eventually 679 00:33:53,120 --> 00:33:55,480 Speaker 1: take hole somewhere? Like what's the scenario in which we 680 00:33:55,520 --> 00:33:58,400 Speaker 1: suddenly everything suddenly freezes and is at the same distance 681 00:33:58,440 --> 00:34:00,640 Speaker 1: from each other everywhere? Right, that's not the picture that 682 00:34:00,640 --> 00:34:02,600 Speaker 1: we're painting. We are painting the picture where things are 683 00:34:02,600 --> 00:34:05,800 Speaker 1: still flying around and still frothing. And so what thermodynamic 684 00:34:05,880 --> 00:34:08,880 Speaker 1: says is that the most likely outcome is that things 685 00:34:08,880 --> 00:34:11,600 Speaker 1: stay smooth. But this is just statistics. It just says 686 00:34:11,640 --> 00:34:14,719 Speaker 1: it's the most likely. There's, of course, quantum randomness. Things 687 00:34:14,760 --> 00:34:18,399 Speaker 1: can fluctuate. It's quantum mechanics, and so things can accidentally 688 00:34:18,440 --> 00:34:20,880 Speaker 1: bump into each other and start to form a hot, spotted, 689 00:34:20,880 --> 00:34:24,000 Speaker 1: denser spot that then collects stuff. Right, We actually talked 690 00:34:24,000 --> 00:34:26,200 Speaker 1: about the probability of this kind of thing happening in 691 00:34:26,239 --> 00:34:29,640 Speaker 1: our Boltspin Brain episode, Like, if you had a perfectly 692 00:34:29,640 --> 00:34:32,960 Speaker 1: smooth universe, what's the possibily fluctuating an atom or a 693 00:34:33,000 --> 00:34:35,840 Speaker 1: star or a brain out of that sort of quantum 694 00:34:35,840 --> 00:34:39,480 Speaker 1: frothing void. Now in our universe, we got a head start, 695 00:34:39,560 --> 00:34:43,000 Speaker 1: because we had inflation. We had tiny little quantum fluctuations 696 00:34:43,000 --> 00:34:46,480 Speaker 1: that got blown up to much bigger fluctuations that then 697 00:34:46,560 --> 00:34:49,320 Speaker 1: gravity you could grab a hold of. But yes, absolutely, 698 00:34:49,320 --> 00:34:52,080 Speaker 1: even in this heat death scenario, you could have random 699 00:34:52,160 --> 00:34:55,759 Speaker 1: quantum fluctuations that lead to overdensities and then do lead 700 00:34:55,800 --> 00:34:59,000 Speaker 1: to the formation of structure. Thermodynamics doesn't say it's impossible. 701 00:34:59,000 --> 00:35:01,440 Speaker 1: It just says it's un likely because that would effectively 702 00:35:01,480 --> 00:35:04,319 Speaker 1: be decreasing entropy. Well, I wonder if in a way, 703 00:35:04,440 --> 00:35:07,359 Speaker 1: gravity is kind of like the anti entropy. You know, 704 00:35:07,480 --> 00:35:09,719 Speaker 1: like I understand this theory of entropy and that if 705 00:35:09,719 --> 00:35:14,160 Speaker 1: you had a perfectly smooth liquid it wouldn't start collapsing. 706 00:35:14,320 --> 00:35:18,799 Speaker 1: But I feel like maybe gravity is there to counteract that, right, Like, 707 00:35:18,920 --> 00:35:22,080 Speaker 1: first of all, you need an infinitely sized universe for 708 00:35:22,160 --> 00:35:25,920 Speaker 1: that to work, otherwise gravity would bring everything together. But 709 00:35:25,960 --> 00:35:29,359 Speaker 1: I feel like, yeah, I feel like gravity somehow counteracts 710 00:35:29,360 --> 00:35:32,640 Speaker 1: this idea that entropy always wins. Well, gravity definitely obeys 711 00:35:32,680 --> 00:35:36,160 Speaker 1: the same laws of thermodynamics. I mean, gravity also wants 712 00:35:36,200 --> 00:35:39,200 Speaker 1: things to like roll downhill. It doesn't like things having 713 00:35:39,200 --> 00:35:41,920 Speaker 1: a lot of potential energy, for example. It likes to 714 00:35:42,000 --> 00:35:44,280 Speaker 1: balance things. So I think it follows the same rules. 715 00:35:44,400 --> 00:35:47,560 Speaker 1: Black holes, for example, which are gravitationally very dense objects, 716 00:35:47,840 --> 00:35:51,359 Speaker 1: do contain an enormous amount of entropy. Entropy is not 717 00:35:51,440 --> 00:35:55,239 Speaker 1: just like order versus disorder, right, It's about how many 718 00:35:55,280 --> 00:35:58,840 Speaker 1: ways you can arrange the microphysical states and represent the 719 00:35:58,880 --> 00:36:01,800 Speaker 1: same macroscopic object. Yeah, I guess it does get a 720 00:36:01,840 --> 00:36:04,600 Speaker 1: little bit philosophical. But just to answer mat Tis this question, 721 00:36:04,680 --> 00:36:07,399 Speaker 1: I guess the answer is. What you're saying is that, yes, 722 00:36:07,520 --> 00:36:09,799 Speaker 1: even in a heat death of the universe, things are 723 00:36:09,840 --> 00:36:12,200 Speaker 1: going to be moving at the quantum level, which maybe 724 00:36:12,320 --> 00:36:14,799 Speaker 1: we'll end up kind of breaking the heat death of 725 00:36:14,800 --> 00:36:17,400 Speaker 1: the universe exactly. There will always be quantum dancing. These 726 00:36:17,440 --> 00:36:20,400 Speaker 1: quantum fields can never go down to zero energy. There 727 00:36:20,440 --> 00:36:23,200 Speaker 1: will always be some energy and so some fluctuations, and 728 00:36:23,239 --> 00:36:26,040 Speaker 1: so it's possible for the universe to get totally smooth 729 00:36:26,120 --> 00:36:28,759 Speaker 1: and ten to the one hundred years and then fluctuate 730 00:36:28,880 --> 00:36:32,279 Speaker 1: some new spot around which structure forms again. And some 731 00:36:32,320 --> 00:36:35,879 Speaker 1: people even think maybe that's the story of our universe. Yeah. Well, 732 00:36:35,920 --> 00:36:37,520 Speaker 1: I think you're saying two things. One is that they 733 00:36:37,520 --> 00:36:40,720 Speaker 1: maybe things fluctuate and maybe they'll start clumping again together. 734 00:36:40,800 --> 00:36:43,680 Speaker 1: But you're also saying maybe they'll fluctuates so crazily like 735 00:36:43,800 --> 00:36:46,480 Speaker 1: suddenly the universe will just going to flip over and 736 00:36:46,520 --> 00:36:49,640 Speaker 1: start over again. Yeah, randomly exactly, But we all have 737 00:36:49,680 --> 00:36:51,560 Speaker 1: to wait ten to the one hundred years to find out. 738 00:36:51,680 --> 00:36:54,000 Speaker 1: I think I'll just watch the recap episode for that. 739 00:36:54,920 --> 00:36:56,880 Speaker 1: Who has time to binch that? Make sure you're not 740 00:36:57,040 --> 00:36:59,520 Speaker 1: watching it while you're on your bicycle. All right, let's 741 00:36:59,520 --> 00:37:02,480 Speaker 1: get to our last question here about dark matter and 742 00:37:02,760 --> 00:37:19,960 Speaker 1: parallel universes. But first let's take a quick break. All right. 743 00:37:19,960 --> 00:37:23,120 Speaker 1: We're answering listener questions about all kinds of things in 744 00:37:23,160 --> 00:37:28,600 Speaker 1: the universe, including cats, rabbits, and ethically questionable physicists, at 745 00:37:29,400 --> 00:37:32,439 Speaker 1: least in thought experiments. And our last question here comes 746 00:37:32,480 --> 00:37:35,840 Speaker 1: from Craig, who hails from Ontario. Hi, Danielle and Horry, 747 00:37:36,200 --> 00:37:39,239 Speaker 1: This is Craig from Ontario, Canada. Thanks for such an 748 00:37:39,239 --> 00:37:43,480 Speaker 1: awesome pod. I was wondering about dark matter. Is there 749 00:37:43,520 --> 00:37:46,360 Speaker 1: any chance that what we experience is dark matter in 750 00:37:46,480 --> 00:37:50,080 Speaker 1: our universe could actually be stuffed with mass in an 751 00:37:50,120 --> 00:37:54,200 Speaker 1: adjacent universe lending its gravity to us. Thank you guys 752 00:37:54,200 --> 00:37:56,320 Speaker 1: for the pod, and I wish you both all the best. 753 00:37:56,840 --> 00:38:01,360 Speaker 1: Whoa mind blown Craig just blue my mind. Also, I 754 00:38:01,400 --> 00:38:04,000 Speaker 1: think I heard a cat in the background of Craig's recording. 755 00:38:04,440 --> 00:38:06,560 Speaker 1: Did you really think I did? I think there's a 756 00:38:06,640 --> 00:38:09,440 Speaker 1: meal there. Or maybe you're just hearing it in your head, Daniel, 757 00:38:09,800 --> 00:38:13,040 Speaker 1: maybe your cats are haunting you. I'm just saying I'm 758 00:38:13,160 --> 00:38:15,960 Speaker 1: looking for new subjects for thought experiments, and Craig, maybe 759 00:38:15,960 --> 00:38:20,320 Speaker 1: you want to volunteer thought experiment or psychological experiments. Can't 760 00:38:20,360 --> 00:38:23,880 Speaker 1: it be both? I guess all psychological experiments are thought experiments. 761 00:38:24,600 --> 00:38:26,760 Speaker 1: That's right, And I'm gonna push back and defend physicist 762 00:38:26,840 --> 00:38:28,600 Speaker 1: a little bit there. We do have a lot of 763 00:38:28,600 --> 00:38:31,640 Speaker 1: crazy thought experiments, like a person in a box out 764 00:38:31,680 --> 00:38:33,799 Speaker 1: in deep space and you got to wonder, how did 765 00:38:33,800 --> 00:38:36,080 Speaker 1: this person sign a consent for him? Is somebody going 766 00:38:36,120 --> 00:38:38,040 Speaker 1: to rescue them? Or they do they have a bathroom 767 00:38:38,080 --> 00:38:39,839 Speaker 1: and water and this kind of stuff. But that's why 768 00:38:39,880 --> 00:38:43,759 Speaker 1: these are just thought experiments and not experiments anybody's ever 769 00:38:43,840 --> 00:38:46,160 Speaker 1: actually going to do right, right, Like you would never 770 00:38:46,200 --> 00:38:50,080 Speaker 1: like build a giant ring Niva, and you know, you know, 771 00:38:50,239 --> 00:38:52,680 Speaker 1: shooting things in incredible energy and then put people on 772 00:38:52,719 --> 00:38:54,520 Speaker 1: top of it, or put an exco city or anything 773 00:38:54,560 --> 00:38:57,600 Speaker 1: like that, right, that would be totally ethically you're RESPONSI, well, 774 00:38:57,600 --> 00:38:59,839 Speaker 1: for example, we would never accelerate cats near the speed 775 00:38:59,840 --> 00:39:03,040 Speaker 1: of light and collide them. Absolutely not. But protons don't 776 00:39:03,040 --> 00:39:07,600 Speaker 1: have the same rights. You're categorically against them. But anyways, Craig, 777 00:39:07,640 --> 00:39:09,200 Speaker 1: whether or not you have a cat, you have an 778 00:39:09,200 --> 00:39:13,520 Speaker 1: interesting question here about dark matter adjacent universes, which is 779 00:39:13,560 --> 00:39:16,640 Speaker 1: an interesting phrase, and so I think his question, and 780 00:39:16,680 --> 00:39:19,400 Speaker 1: I have to say, I think I told you this 781 00:39:19,480 --> 00:39:22,080 Speaker 1: theory a long time ago. I remember we were driving 782 00:39:22,120 --> 00:39:24,520 Speaker 1: somewhere for our book tour and I was like, hey, Daniel, 783 00:39:24,560 --> 00:39:26,440 Speaker 1: I have a theory about dark matter, and I think 784 00:39:26,480 --> 00:39:30,360 Speaker 1: it was exactly this theory, which means Craig is a genius, 785 00:39:31,760 --> 00:39:34,520 Speaker 1: or it means Craig should be a cartoonist. Yeah, maybe 786 00:39:35,160 --> 00:39:37,839 Speaker 1: maybe you'll find more success in that like I did. 787 00:39:38,120 --> 00:39:40,400 Speaker 1: But yeah, it's kind of an interesting question, like because 788 00:39:40,400 --> 00:39:42,560 Speaker 1: we don't know there's dark matter in this universe. We 789 00:39:42,680 --> 00:39:45,080 Speaker 1: notice it's there, but we don't know what it is. 790 00:39:45,560 --> 00:39:48,440 Speaker 1: And so his idea, or I guess I should say 791 00:39:48,440 --> 00:39:53,399 Speaker 1: our idea, the Craig cam theory about dark matter, that 792 00:39:54,040 --> 00:39:57,319 Speaker 1: maybe what we feel as dark matter is actually like 793 00:39:57,880 --> 00:40:01,040 Speaker 1: mass in a parallel universe at some how leaking over 794 00:40:01,400 --> 00:40:05,359 Speaker 1: that somehow we can see through gravity. M Yeah, and 795 00:40:05,400 --> 00:40:08,160 Speaker 1: I love this idea. It's really clever. But let's take 796 00:40:08,160 --> 00:40:10,640 Speaker 1: a step back because you said there's dark matter in 797 00:40:10,640 --> 00:40:13,520 Speaker 1: our universe. But I think Craig's question is asking us 798 00:40:13,560 --> 00:40:16,719 Speaker 1: to reconsider that, because really, what do we observe. We 799 00:40:16,719 --> 00:40:22,479 Speaker 1: observe gravity. We see something is contributing gravity to how 800 00:40:22,520 --> 00:40:26,080 Speaker 1: galaxies spin, and how the large scale structure the universe formed, 801 00:40:26,080 --> 00:40:29,160 Speaker 1: and how the ripples in the early universe plasma were 802 00:40:29,200 --> 00:40:32,440 Speaker 1: created and propagated. What we see is gravity that we 803 00:40:32,560 --> 00:40:35,680 Speaker 1: cannot explain. We attribute that to dark matter. We say 804 00:40:35,760 --> 00:40:37,759 Speaker 1: there must be some missing mass in our universe we 805 00:40:37,800 --> 00:40:41,239 Speaker 1: never observed before. It's basically what we say dark matter is. 806 00:40:41,480 --> 00:40:44,560 Speaker 1: But what we actually observe is the gravity. So I 807 00:40:44,600 --> 00:40:46,359 Speaker 1: think Craig's question is, like, how do we know that's 808 00:40:46,400 --> 00:40:49,040 Speaker 1: mass in our universe and not just gravity leaking in 809 00:40:49,160 --> 00:40:52,920 Speaker 1: from some other universe where that mass is right? Right, 810 00:40:52,960 --> 00:40:55,080 Speaker 1: Although you're kind of parsing hare is here, because like 811 00:40:55,160 --> 00:40:57,839 Speaker 1: if there is another universe and leaking into ours, then 812 00:40:57,920 --> 00:41:01,200 Speaker 1: there's like overlap, right, I mean that universe is partly 813 00:41:01,200 --> 00:41:04,960 Speaker 1: in our universe, right, and so it's technically kind of 814 00:41:05,040 --> 00:41:07,239 Speaker 1: in our universe too, exactly. And that is the hair 815 00:41:07,320 --> 00:41:09,200 Speaker 1: I think we are splitting here today, which is what 816 00:41:09,239 --> 00:41:12,839 Speaker 1: does it mean to be in an adjacent universe? Right? 817 00:41:13,000 --> 00:41:15,520 Speaker 1: If this mass is in another universe and we don't 818 00:41:15,560 --> 00:41:18,120 Speaker 1: interact with it except through gravity, is it really in 819 00:41:18,239 --> 00:41:21,080 Speaker 1: another universe? If we can interact with it, is it 820 00:41:21,120 --> 00:41:23,560 Speaker 1: in another universe? I mean, I'm interacting with my chair 821 00:41:23,640 --> 00:41:25,759 Speaker 1: and my desk right now. So we say that they're 822 00:41:25,840 --> 00:41:28,000 Speaker 1: part of the universe. Could you say they're in another 823 00:41:28,120 --> 00:41:31,759 Speaker 1: universe but we can still somehow interact with them. I 824 00:41:31,760 --> 00:41:34,080 Speaker 1: don't know. I would say that things in another universe 825 00:41:34,080 --> 00:41:36,920 Speaker 1: are things you cannot interact with. And so if we're 826 00:41:36,960 --> 00:41:39,799 Speaker 1: interacting with this stuff, if we're feeling it's gravity, then 827 00:41:39,840 --> 00:41:42,160 Speaker 1: it's in our universe. And that's not like a physics 828 00:41:42,280 --> 00:41:45,239 Speaker 1: argument or philosophy argument. It's really just sort of like semantics. 829 00:41:45,280 --> 00:41:48,160 Speaker 1: It's like, what do you call a universe? Yeah, and 830 00:41:48,200 --> 00:41:52,640 Speaker 1: we never argue semantics here on this podcast. Well, I 831 00:41:52,680 --> 00:41:55,759 Speaker 1: think there's kind of two interesting ideas here in Craig's question, right, 832 00:41:55,880 --> 00:41:59,239 Speaker 1: Like one like maybe in our universe there's a whole 833 00:41:59,239 --> 00:42:01,960 Speaker 1: other universe on top of us of particles that our 834 00:42:02,000 --> 00:42:05,120 Speaker 1: particles don't interact with. There's like planets and suns and 835 00:42:05,200 --> 00:42:08,000 Speaker 1: stars and photons and things like that that just don't 836 00:42:08,000 --> 00:42:11,279 Speaker 1: like interact with us, our kind of particles. So that's 837 00:42:11,320 --> 00:42:13,239 Speaker 1: why we don't see it, but they're there. They're like 838 00:42:13,280 --> 00:42:16,160 Speaker 1: it's like a ghost universe on top of ours, but somehow, 839 00:42:16,239 --> 00:42:19,000 Speaker 1: like the gravity, we do kind of feel its presence. 840 00:42:19,040 --> 00:42:22,520 Speaker 1: It's gravity, and that's what maybe we see as dark matter. 841 00:42:22,719 --> 00:42:25,880 Speaker 1: Then there's the other idea that maybe it is another universe, 842 00:42:25,920 --> 00:42:28,719 Speaker 1: like maybe it's the multiverse or the quantum multiverse or 843 00:42:29,000 --> 00:42:31,680 Speaker 1: you know these quantum foam bubble universes. It would be 844 00:42:31,680 --> 00:42:34,560 Speaker 1: considered by some as a totally different universe that somehow 845 00:42:34,760 --> 00:42:37,719 Speaker 1: leaks into hours. And so those are kind of two 846 00:42:37,719 --> 00:42:40,279 Speaker 1: different ideas, right, that's like maybe we share the same 847 00:42:40,280 --> 00:42:42,640 Speaker 1: space or maybe we don't share the same space. Yeah, 848 00:42:42,680 --> 00:42:44,920 Speaker 1: those are two different ideas and they're really fun. The 849 00:42:44,960 --> 00:42:47,680 Speaker 1: first one I think is beautiful because it's sort of 850 00:42:47,719 --> 00:42:51,000 Speaker 1: our current conception of the universe, suggesting that there is 851 00:42:51,000 --> 00:42:53,120 Speaker 1: all this matter out there that we can't interact with 852 00:42:53,200 --> 00:42:56,920 Speaker 1: except through gravity. Gravity is like the great unifier because 853 00:42:56,920 --> 00:43:00,240 Speaker 1: it interacts with everything. Anything that has mass or energy, 854 00:43:00,440 --> 00:43:03,759 Speaker 1: regardless of any other quantum properties, it has gravity will 855 00:43:03,800 --> 00:43:06,000 Speaker 1: talk to it. So if there's anything else out there 856 00:43:06,080 --> 00:43:08,239 Speaker 1: in the universe, even if we can't interact with it, 857 00:43:08,239 --> 00:43:11,160 Speaker 1: even if it has like weird particles and weird forces 858 00:43:11,200 --> 00:43:14,000 Speaker 1: that are not overlapping at all with ours, we would 859 00:43:14,000 --> 00:43:16,680 Speaker 1: know it because of its gravity. And you can sort 860 00:43:16,680 --> 00:43:18,799 Speaker 1: of think of that as like another universe, as you say, 861 00:43:18,840 --> 00:43:21,320 Speaker 1: like a ghost universe. You can imagine all these particles 862 00:43:21,320 --> 00:43:24,840 Speaker 1: out there with new dark forces and dark charges and 863 00:43:24,960 --> 00:43:27,640 Speaker 1: dark physics and doing their dark stuff, maybe making dark 864 00:43:27,640 --> 00:43:31,560 Speaker 1: planets or completely different emerging dark phenomena that we can't 865 00:43:31,600 --> 00:43:35,279 Speaker 1: even imagine because fundamentally they're very different physics at their core, 866 00:43:35,320 --> 00:43:38,319 Speaker 1: and how that bubbles up to creating ice cream or 867 00:43:38,400 --> 00:43:41,640 Speaker 1: not depends on that fundamental physics. So even that is 868 00:43:41,640 --> 00:43:44,800 Speaker 1: fascinating to me. That's sort of like being another universe 869 00:43:44,840 --> 00:43:46,719 Speaker 1: on top of ours, because it says that we are 870 00:43:46,800 --> 00:43:50,080 Speaker 1: only experiencing a slice of this universe, and we already 871 00:43:50,120 --> 00:43:52,200 Speaker 1: know that's true. We already know there's lots of stuff 872 00:43:52,200 --> 00:43:54,600 Speaker 1: out there. We can't see neutrinos and stuff, though we 873 00:43:54,600 --> 00:43:57,960 Speaker 1: can detect them through some quantum interactions. But gravity is 874 00:43:58,000 --> 00:44:00,800 Speaker 1: this awesome way to say if there's something else, anything 875 00:44:00,840 --> 00:44:03,400 Speaker 1: else in our space, then we will see it. And 876 00:44:03,400 --> 00:44:05,400 Speaker 1: so the other idea which you bring up is like, 877 00:44:05,440 --> 00:44:08,879 Speaker 1: maybe there's another universe that gravity can somehow interact with, 878 00:44:09,000 --> 00:44:12,239 Speaker 1: Like maybe there is other matter, and if it were 879 00:44:12,280 --> 00:44:14,600 Speaker 1: in our space, we would interact with it and we 880 00:44:14,680 --> 00:44:17,520 Speaker 1: would see it. Right, it is sort of normalish matter. 881 00:44:17,560 --> 00:44:20,720 Speaker 1: It's just like in some other space. But yet gravity 882 00:44:20,800 --> 00:44:23,759 Speaker 1: is connecting our space and their space. It's sort of 883 00:44:23,760 --> 00:44:26,080 Speaker 1: like the other idea you proposed, And that's a little 884 00:44:26,080 --> 00:44:30,480 Speaker 1: bit theoretically problematic because remember gravity is about space. Gravity 885 00:44:30,520 --> 00:44:33,319 Speaker 1: says when you have mass in space, it bends, and 886 00:44:33,360 --> 00:44:36,440 Speaker 1: so if this mass is bending our space, then it's 887 00:44:36,480 --> 00:44:39,719 Speaker 1: sort of in our space. There's no other way for 888 00:44:40,080 --> 00:44:43,640 Speaker 1: that mass to bend our space without being in our space. 889 00:44:44,440 --> 00:44:46,680 Speaker 1: You're saying like, if there is another universe out there 890 00:44:46,680 --> 00:44:49,839 Speaker 1: that's separate from ours, and I like that this you made, 891 00:44:49,880 --> 00:44:51,960 Speaker 1: like if it were in our universe, we would interact 892 00:44:52,000 --> 00:44:54,000 Speaker 1: with it. But it is in a different kind of 893 00:44:54,000 --> 00:44:57,560 Speaker 1: space or phase or whatever, and so therefore it's another universe. 894 00:44:57,600 --> 00:44:59,640 Speaker 1: But you're saying, like, if we do feel it somehow, 895 00:45:00,000 --> 00:45:02,759 Speaker 1: and there is a connection which means you should lump 896 00:45:02,800 --> 00:45:07,360 Speaker 1: both of our universe together into one word called the universe. Yeah, exactly, 897 00:45:07,640 --> 00:45:10,520 Speaker 1: if it's bending our space, then it's in our space. 898 00:45:10,640 --> 00:45:13,600 Speaker 1: By definition, it can't both be bending our space and 899 00:45:13,680 --> 00:45:16,520 Speaker 1: not be in our space, right, Like if I take 900 00:45:16,560 --> 00:45:19,000 Speaker 1: a tunnel from my house to your house, suddenly it's 901 00:45:19,040 --> 00:45:26,120 Speaker 1: my house too, it's our house. I guess, let's part 902 00:45:26,239 --> 00:45:30,320 Speaker 1: the legalism of that put all the work into the tunnel, 903 00:45:31,040 --> 00:45:33,919 Speaker 1: I suppose. So there are other interesting wrinkles here though, because, 904 00:45:33,960 --> 00:45:37,360 Speaker 1: for example, it's possible that gravity acts in ways different 905 00:45:37,400 --> 00:45:40,279 Speaker 1: from all the other interactions. Like it might be that 906 00:45:40,360 --> 00:45:44,279 Speaker 1: the universe has multiple dimensions, right the ways that we 907 00:45:44,320 --> 00:45:46,359 Speaker 1: can move x, y, and z, there might be more 908 00:45:46,440 --> 00:45:49,520 Speaker 1: of those, And one theory is that gravity can operate 909 00:45:49,600 --> 00:45:52,600 Speaker 1: in those other dimensions and the other forces cannot. So 910 00:45:52,640 --> 00:45:55,960 Speaker 1: it's possible there are other quantum objects and quantum forces 911 00:45:55,960 --> 00:45:59,279 Speaker 1: that can operate in those other dimensions that we can't 912 00:45:59,320 --> 00:46:02,000 Speaker 1: operate in. Gravity would be sort of unifying. It would 913 00:46:02,000 --> 00:46:04,719 Speaker 1: still be in our universe, right, but we wouldn't be 914 00:46:04,719 --> 00:46:06,960 Speaker 1: able to see them or interact with them, but they'd 915 00:46:06,960 --> 00:46:09,560 Speaker 1: be moving through sort of like other dimensions instead of 916 00:46:09,560 --> 00:46:11,759 Speaker 1: the three that we have. So I guess maybe it 917 00:46:11,800 --> 00:46:14,400 Speaker 1: all depends on how you define the universe, right, I mean, 918 00:46:14,520 --> 00:46:17,080 Speaker 1: physics came up with the cause of the word multiverse 919 00:46:17,160 --> 00:46:19,359 Speaker 1: for kind of a reason, right, to describe kind of 920 00:46:19,360 --> 00:46:23,200 Speaker 1: like a collection of mini universes. And there's a whole 921 00:46:23,239 --> 00:46:26,319 Speaker 1: set of different multiverses as like a multi multiverse, but 922 00:46:26,440 --> 00:46:29,200 Speaker 1: in all of them there's no way to interact. Like 923 00:46:29,239 --> 00:46:31,520 Speaker 1: there's the quantum multiverse that we just talked about in 924 00:46:31,600 --> 00:46:33,720 Speaker 1: terms of the Shooting verse cat Well, there's two different 925 00:46:33,719 --> 00:46:37,120 Speaker 1: branches of the universe reflecting different possibilities, but the branches 926 00:46:37,120 --> 00:46:39,920 Speaker 1: can never interact with each other gravity and one doesn't 927 00:46:39,960 --> 00:46:43,640 Speaker 1: leaked into the other. There's the bubble multiverse that suggests 928 00:46:43,800 --> 00:46:47,280 Speaker 1: the bubbles of normal space were popped out of inflationary matter, 929 00:46:47,440 --> 00:46:50,800 Speaker 1: but these would be separated by inflating matter, so that'd 930 00:46:50,800 --> 00:46:53,200 Speaker 1: be so far away we can never interact with them. 931 00:46:53,239 --> 00:46:56,200 Speaker 1: And all these different multiverse theories, you cannot interact with 932 00:46:56,280 --> 00:46:59,840 Speaker 1: the other universes in the multiverse. That's only something in 933 00:47:00,000 --> 00:47:03,359 Speaker 1: a Marvel cinematic universe that is possible, and that all 934 00:47:03,360 --> 00:47:07,279 Speaker 1: that stuff is real too anyways, Right, Well, it's making 935 00:47:07,320 --> 00:47:11,080 Speaker 1: real money, that's for sure. Well, I think maybe the 936 00:47:11,160 --> 00:47:14,120 Speaker 1: answer for Craig here to this question of whether dark 937 00:47:14,160 --> 00:47:17,480 Speaker 1: matter is just stuff that we feel from another universe. 938 00:47:17,960 --> 00:47:20,520 Speaker 1: I feel like the answer is, yes, it's possible it 939 00:47:20,520 --> 00:47:24,200 Speaker 1: could be the case. But then a physicist like you, 940 00:47:24,320 --> 00:47:26,759 Speaker 1: Daniel will come in and say, well, technically, if we're 941 00:47:26,760 --> 00:47:29,120 Speaker 1: feeling it, then it's part of our universe, and sort 942 00:47:29,120 --> 00:47:32,879 Speaker 1: of try to cancel out the question. I would say, 943 00:47:32,880 --> 00:47:35,560 Speaker 1: if we're feeling it, it's in our universe. Yeah, absolutely, 944 00:47:35,800 --> 00:47:38,000 Speaker 1: But I guess the main main idea is that it 945 00:47:38,000 --> 00:47:40,160 Speaker 1: could be that dark matter is just kind of part 946 00:47:40,160 --> 00:47:43,480 Speaker 1: of this whole set of things that exists out there 947 00:47:43,560 --> 00:47:46,359 Speaker 1: that we just don't mostly notice. And I think the 948 00:47:46,400 --> 00:47:49,560 Speaker 1: spirit of Craig's question is that there's the possibility of 949 00:47:49,560 --> 00:47:52,680 Speaker 1: a much wider and broader kind of reality than the 950 00:47:52,719 --> 00:47:55,520 Speaker 1: one we experience and that we think about. And that's 951 00:47:55,520 --> 00:47:57,960 Speaker 1: the cool thing about dark matter and about gravity is 952 00:47:58,000 --> 00:47:59,959 Speaker 1: that it lets us explore. It gives us a poor 953 00:48:00,000 --> 00:48:02,680 Speaker 1: to everything that's out there in every part of our 954 00:48:02,800 --> 00:48:07,080 Speaker 1: universe because gravity is universal, and so that's the really 955 00:48:07,160 --> 00:48:09,640 Speaker 1: exciting thing about it to me is not only the 956 00:48:09,680 --> 00:48:12,800 Speaker 1: universe could be very different from the universe we experience 957 00:48:12,840 --> 00:48:15,279 Speaker 1: and we've imagined, but that we have a way to 958 00:48:15,400 --> 00:48:18,640 Speaker 1: discover it and explore it. So gravity is really this 959 00:48:18,880 --> 00:48:23,000 Speaker 1: wonderful handle on everything that's out there. Interesting. Yeah, it's 960 00:48:23,040 --> 00:48:26,320 Speaker 1: sort of like a universal currency for the multiverse exactly. 961 00:48:26,360 --> 00:48:29,480 Speaker 1: It's pretty hard to exist without any gravity. All right, Well, 962 00:48:29,520 --> 00:48:31,640 Speaker 1: I think that answers correct questions and all of our 963 00:48:31,760 --> 00:48:34,520 Speaker 1: questions today. Those were really great questions. Thank you for 964 00:48:34,560 --> 00:48:37,000 Speaker 1: taking them in. Yes, thank you everybody who's thinking about 965 00:48:37,040 --> 00:48:40,040 Speaker 1: the universe and being curious. And if you have questions 966 00:48:40,040 --> 00:48:41,800 Speaker 1: and have been too shy to send them in, please 967 00:48:42,080 --> 00:48:44,319 Speaker 1: don't hold back or right to us two questions at 968 00:48:44,400 --> 00:48:46,799 Speaker 1: Daniel and Jorge dot com. The only thing we ask 969 00:48:46,960 --> 00:48:49,400 Speaker 1: is that you were ethical in your thought experiments, or 970 00:48:49,440 --> 00:48:51,400 Speaker 1: at least to them in another universe. Then then you 971 00:48:51,440 --> 00:48:54,880 Speaker 1: can do whatever you want, right, No, man, Other universes 972 00:48:54,880 --> 00:48:57,120 Speaker 1: have feelings too, though. I guess if we're feeling them, 973 00:48:57,160 --> 00:49:00,239 Speaker 1: then they're in our universe by my rule. Yeah, you 974 00:49:00,320 --> 00:49:03,680 Speaker 1: just canceled your own question. I guess I did. All right. Well, 975 00:49:03,719 --> 00:49:06,919 Speaker 1: we hope you enjoyed that. Thanks for joining us, see 976 00:49:06,920 --> 00:49:17,240 Speaker 1: you next time. Thanks for listening and remember that. Daniel 977 00:49:17,280 --> 00:49:20,680 Speaker 1: and Jorge Explain the Universe is a production of iHeartRadio. 978 00:49:20,960 --> 00:49:24,840 Speaker 1: For more podcast from my heart Radio, visit the iHeartRadio app, 979 00:49:25,120 --> 00:49:28,600 Speaker 1: Apple Podcasts, or wherever you listen to your favorite shows.