1 00:00:08,560 --> 00:00:11,600 Speaker 1: Hey, Daniel, do you ever get frustrated by, you know, 2 00:00:11,680 --> 00:00:14,840 Speaker 1: asking the biggest questions in the universe all the time? Never? 3 00:00:15,080 --> 00:00:17,720 Speaker 1: I live for it. I mean, what could be more fun? 4 00:00:18,320 --> 00:00:22,919 Speaker 1: How about finding the answers sometimes? Oh? There are always 5 00:00:22,960 --> 00:00:26,639 Speaker 1: answers out there waiting for us to discover them. You know, really, 6 00:00:26,680 --> 00:00:28,840 Speaker 1: you think all the big questions in the universe have 7 00:00:29,040 --> 00:00:31,160 Speaker 1: answers to them? What if they don't. I think that 8 00:00:31,200 --> 00:00:35,479 Speaker 1: even the deepest, hardest, craziest questions in the universe have answers, 9 00:00:35,560 --> 00:00:38,360 Speaker 1: and one day some human will know them. Hopefully that 10 00:00:38,440 --> 00:00:40,800 Speaker 1: human is you or one of our listeners. What if 11 00:00:40,840 --> 00:00:43,519 Speaker 1: the big questions don't have answers? You mean, like, is 12 00:00:43,560 --> 00:00:46,239 Speaker 1: white chocolate really chocolate? Can you just say? I don't know. 13 00:00:46,880 --> 00:00:48,639 Speaker 1: That's what I told my kids all the time. That's 14 00:00:48,680 --> 00:00:50,920 Speaker 1: an answer, right? How about ask your mother? Is that 15 00:00:50,960 --> 00:00:53,000 Speaker 1: an answer to the question? Who ate all the chocolate? 16 00:00:53,159 --> 00:01:10,560 Speaker 1: That one is also asked your mother? Hi? I'm poor 17 00:01:10,600 --> 00:01:13,479 Speaker 1: Hammy car Tennis and the creator of PhD comics. Hi, 18 00:01:13,640 --> 00:01:16,280 Speaker 1: I'm Daniel. I'm a particle of physicist and a professor 19 00:01:16,319 --> 00:01:19,000 Speaker 1: at UC Irvine, and I will continue to eat chocolate 20 00:01:19,080 --> 00:01:21,640 Speaker 1: until all the questions are answered. I thought you were 21 00:01:21,680 --> 00:01:23,440 Speaker 1: going to say that you you ate all the chocolate, 22 00:01:24,080 --> 00:01:26,240 Speaker 1: but I guess you still have answers to find. That's right. 23 00:01:26,240 --> 00:01:28,880 Speaker 1: As long as they keep making chocolate, I'll keep asking 24 00:01:28,959 --> 00:01:31,080 Speaker 1: questions and looking for answers. I'm not sure where this 25 00:01:31,080 --> 00:01:34,319 Speaker 1: correlation between answers and chocolate came from, Daniel, Are you 26 00:01:34,360 --> 00:01:36,559 Speaker 1: sure you're not just making it up? I'm not making 27 00:01:36,560 --> 00:01:38,720 Speaker 1: that up. You know that there's a tight correlation between 28 00:01:38,760 --> 00:01:42,080 Speaker 1: the amount of chocolate consumed per capita and the number 29 00:01:42,080 --> 00:01:46,040 Speaker 1: of Nobel prizes one per capita for countries Switzerland is 30 00:01:46,080 --> 00:01:49,600 Speaker 1: like knocking it out of the park. Isn't that weird? Though? 31 00:01:49,800 --> 00:01:52,960 Speaker 1: Isn't the Nobel price based out of Switzerland? No, it's Sweden, man, 32 00:01:53,160 --> 00:01:58,760 Speaker 1: Hello Sweden. Wrong as w country were. Clearly, Sweden just 33 00:01:58,800 --> 00:02:01,880 Speaker 1: needs to be more chocolate. Clearly, everybody needs to eat 34 00:02:01,880 --> 00:02:04,080 Speaker 1: more chocolate. I mean, it's good for everything. It's good 35 00:02:04,120 --> 00:02:05,920 Speaker 1: for your mind, it's good for your soul. I'm not 36 00:02:05,920 --> 00:02:09,640 Speaker 1: sure it's good for your waistline or your heart a 37 00:02:09,680 --> 00:02:12,760 Speaker 1: little bit. That's a true correlation, right like that. If 38 00:02:12,840 --> 00:02:15,120 Speaker 1: you make a plot of the countries that have Nobel 39 00:02:15,160 --> 00:02:18,079 Speaker 1: Prizes and the amount of chocolate they eat per capita. Supposedly, 40 00:02:18,160 --> 00:02:20,520 Speaker 1: I mean I haven't looked into the data, but supposedly 41 00:02:20,520 --> 00:02:22,239 Speaker 1: there's a correlation, right, Yeah, I think we have a 42 00:02:22,280 --> 00:02:24,400 Speaker 1: plot of that in the opening of one of our books. 43 00:02:24,440 --> 00:02:28,079 Speaker 1: So the data is there, the correlation is true. The causality, 44 00:02:28,520 --> 00:02:31,040 Speaker 1: I'm not exactly sure. It doesn't mean that you should 45 00:02:31,120 --> 00:02:33,840 Speaker 1: force feed chocolate to your school children in order to 46 00:02:33,840 --> 00:02:36,520 Speaker 1: get Nobel prizes in twenty years. You mean, like the 47 00:02:36,560 --> 00:02:39,240 Speaker 1: causality could be the other way around, Like winning a 48 00:02:39,240 --> 00:02:41,359 Speaker 1: lot of Noble prices could cause you to eat a 49 00:02:41,400 --> 00:02:44,160 Speaker 1: lot of chocolate. Yeah. Maybe they're just celebrating their Noble 50 00:02:44,200 --> 00:02:46,920 Speaker 1: prizes by eating chocolate, right, Or maybe there's a chemical 51 00:02:46,960 --> 00:02:49,520 Speaker 1: and chocolate. It could be big chocolate, you know, just 52 00:02:49,600 --> 00:02:53,920 Speaker 1: be a big conspiracy, Oh, conspiracy between big chocolate and 53 00:02:53,919 --> 00:02:58,560 Speaker 1: big Nobele. Yeah, the big science and big chocolate. They're 54 00:02:58,600 --> 00:03:00,880 Speaker 1: already trying to make us all bigger. I guess that's 55 00:03:01,000 --> 00:03:05,239 Speaker 1: right exactly. We're asking bigger questions by making our scientists 56 00:03:05,320 --> 00:03:08,520 Speaker 1: even bigger, especially around the waistline. I occupy a larger 57 00:03:08,560 --> 00:03:11,080 Speaker 1: and larger fraction in the universe every year, that's right. 58 00:03:11,120 --> 00:03:13,839 Speaker 1: If you occupy larger fractions of the universe. There's less 59 00:03:13,840 --> 00:03:17,200 Speaker 1: of the universe to explore. Technically speaking, Yeah, well that 60 00:03:17,280 --> 00:03:20,000 Speaker 1: must be what dark matter is. After all, it's just 61 00:03:20,960 --> 00:03:24,760 Speaker 1: overweight physicists. I guess eating dark chocolate because white chocolate 62 00:03:25,000 --> 00:03:27,440 Speaker 1: not chocolate. Maybe that's what happened out in space, like 63 00:03:27,480 --> 00:03:30,399 Speaker 1: all these aliens that are more advanced, you know, sort 64 00:03:30,400 --> 00:03:35,040 Speaker 1: of reach the chocolate singularity and just based out of 65 00:03:35,080 --> 00:03:38,240 Speaker 1: the electronic neetic spectrum. See how much progress we've made already. 66 00:03:38,280 --> 00:03:41,920 Speaker 1: I don't think anybody ever said the phrase chocolate singularity before. 67 00:03:42,320 --> 00:03:46,080 Speaker 1: So that's progress right there, chocolate fuel progress. Yeah, just 68 00:03:46,120 --> 00:03:50,320 Speaker 1: talking about chocolate makes even a noble price boom. But anyways, 69 00:03:50,320 --> 00:03:52,720 Speaker 1: welcome to our podcast, Daniel and Horror Explain the Universe, 70 00:03:52,800 --> 00:03:55,119 Speaker 1: a production of I Heart Radio in which we eat 71 00:03:55,120 --> 00:03:58,440 Speaker 1: our way towards answers to some of the biggest, tastiest, 72 00:03:58,520 --> 00:04:02,760 Speaker 1: most delicious question humans have ever asked. Questions about the 73 00:04:02,800 --> 00:04:05,120 Speaker 1: size of the universe, the shape of the universe, the 74 00:04:05,160 --> 00:04:08,720 Speaker 1: motion of the universe, the fundamental nature of the reality 75 00:04:08,800 --> 00:04:12,840 Speaker 1: we find ourselves in as curious conscious beings trying desperately 76 00:04:12,880 --> 00:04:15,800 Speaker 1: to understand what's going on and where is my next 77 00:04:15,800 --> 00:04:18,440 Speaker 1: piece of chocolate? Coming from that's right, because the universe 78 00:04:18,520 --> 00:04:22,320 Speaker 1: is full of amazing and incredible things like delicious snacks 79 00:04:22,360 --> 00:04:25,680 Speaker 1: and dark matter and sometimes dark delicious snacks at all 80 00:04:25,720 --> 00:04:28,640 Speaker 1: at the same time, and we're all just wondering what's 81 00:04:28,680 --> 00:04:30,799 Speaker 1: going on, what's out there, and how does it work. 82 00:04:31,000 --> 00:04:33,279 Speaker 1: And some of us get to do that for a living. 83 00:04:33,400 --> 00:04:36,080 Speaker 1: I mean, ask questions, not each chocolate. Nobody pays me 84 00:04:36,120 --> 00:04:39,320 Speaker 1: to do that yet, but it does fuel my curiosity 85 00:04:39,320 --> 00:04:42,680 Speaker 1: about the fundamental nature of what things are like out there. Yeah, 86 00:04:42,720 --> 00:04:45,720 Speaker 1: I guess you're a professional question asker, Daniel. Would you 87 00:04:45,760 --> 00:04:48,440 Speaker 1: say that's that's how you can describe a researcher. Yeah. 88 00:04:48,440 --> 00:04:51,240 Speaker 1: Everybody who have decided to spend their life doing science 89 00:04:51,360 --> 00:04:54,320 Speaker 1: has done so because there's a question that drives them. 90 00:04:54,520 --> 00:04:57,120 Speaker 1: Of course, I'm curious about lots of questions in science 91 00:04:57,160 --> 00:04:59,400 Speaker 1: that I don't personally work on, But everybody who's a 92 00:04:59,440 --> 00:05:03,400 Speaker 1: scientist has their own personal questions that drive them to 93 00:05:03,440 --> 00:05:06,119 Speaker 1: spend their life asking it. You know. Maybe it's about 94 00:05:06,320 --> 00:05:10,080 Speaker 1: how birds communicate and choose partners. Maybe it's about how 95 00:05:10,120 --> 00:05:13,080 Speaker 1: the Earth was formed. Maybe it's about the fundamental nature 96 00:05:13,200 --> 00:05:17,080 Speaker 1: of space and time. It's this personal curiosity that drives 97 00:05:17,200 --> 00:05:20,240 Speaker 1: science forward. Yeah, and you forgot the very important question 98 00:05:20,240 --> 00:05:22,360 Speaker 1: how do you make chocolate fat free? That would also 99 00:05:22,400 --> 00:05:25,160 Speaker 1: move signs forward a lot. Apparently, you mean, how do 100 00:05:25,200 --> 00:05:30,600 Speaker 1: you make chocolate chocolate free? How do you make chocolate 101 00:05:30,600 --> 00:05:33,479 Speaker 1: still delicious but a little healthier? Maybe? Yeah, The answer 102 00:05:33,520 --> 00:05:36,760 Speaker 1: that one is you can't. The unhealthiness is part of 103 00:05:36,800 --> 00:05:39,320 Speaker 1: why it's so delicious. Oh, I say, it's the guilty 104 00:05:39,360 --> 00:05:42,200 Speaker 1: pleasure of it that you like. Oh my goodness, it's 105 00:05:42,240 --> 00:05:45,440 Speaker 1: just got a little extra dark. But I guess. Yeah, 106 00:05:45,480 --> 00:05:48,000 Speaker 1: you're a professional question asker, which means you're also sort 107 00:05:48,000 --> 00:05:50,880 Speaker 1: of a professional head spinner, right, because I mean your 108 00:05:50,960 --> 00:05:52,880 Speaker 1: job is not just to answer questions that your job 109 00:05:52,960 --> 00:05:56,080 Speaker 1: is to find answers to crazy questions and find crazy 110 00:05:56,080 --> 00:05:59,440 Speaker 1: answers right to leave people's head spinning. That's right. Sometimes 111 00:05:59,440 --> 00:06:03,159 Speaker 1: when you under these deep questions about the universe, you wonder, like, 112 00:06:03,279 --> 00:06:05,680 Speaker 1: how can we even get started? How do we take 113 00:06:05,720 --> 00:06:09,360 Speaker 1: that first step towards that future where some human knows 114 00:06:09,440 --> 00:06:12,279 Speaker 1: the answer to those questions as like an actual fact. 115 00:06:12,800 --> 00:06:16,640 Speaker 1: Sometimes it can be inconceivable to probe such big questions 116 00:06:16,640 --> 00:06:19,360 Speaker 1: and know like how to get started. Yeah, and hopefully 117 00:06:19,400 --> 00:06:22,239 Speaker 1: it's a future we're not just one human not the answer. 118 00:06:22,279 --> 00:06:25,240 Speaker 1: Hopefully that person gets to tell other humans yes. But 119 00:06:25,279 --> 00:06:28,360 Speaker 1: there's always a first human, right. That's the joy of discovery, 120 00:06:28,400 --> 00:06:31,520 Speaker 1: to be the first person to know something about the 121 00:06:31,640 --> 00:06:34,000 Speaker 1: universe that nobody else knows, just like there was a 122 00:06:34,080 --> 00:06:36,800 Speaker 1: first person to taste every kind of fruit on Earth, 123 00:06:37,160 --> 00:06:40,000 Speaker 1: or first person to see every single mountain or to 124 00:06:40,120 --> 00:06:42,800 Speaker 1: walk along a beach. There's always a first and that's 125 00:06:42,839 --> 00:06:45,240 Speaker 1: the joy of discovery. You want to be the one 126 00:06:45,279 --> 00:06:47,400 Speaker 1: who figures it out, not reading about it in the 127 00:06:47,440 --> 00:06:50,080 Speaker 1: science times of the newspaper, right right, Although the way 128 00:06:50,120 --> 00:06:52,599 Speaker 1: science works, you're never quite the first human, right because 129 00:06:52,640 --> 00:06:55,080 Speaker 1: you always need things to be pu reviewed, right, like 130 00:06:55,400 --> 00:06:57,520 Speaker 1: somebody needs to check your answer. You can't just like 131 00:06:57,839 --> 00:07:00,240 Speaker 1: come up with an idea and have absolute certain that 132 00:07:00,279 --> 00:07:03,160 Speaker 1: it's true, can you. You can't ever certain. But there 133 00:07:03,160 --> 00:07:06,200 Speaker 1: are moments when you do an experiment and the results 134 00:07:06,200 --> 00:07:09,320 Speaker 1: are just very conclusive. These moments of discovery where you've 135 00:07:09,320 --> 00:07:11,680 Speaker 1: designed your experiment in a way to like corner the 136 00:07:11,760 --> 00:07:15,120 Speaker 1: universe to revealing some truth to you. That a podcast 137 00:07:15,120 --> 00:07:18,200 Speaker 1: about pulsar discovery last year in which we played audio 138 00:07:18,240 --> 00:07:20,840 Speaker 1: of the astronomers watching the data come in in real 139 00:07:21,000 --> 00:07:24,120 Speaker 1: time and having that moment of discovery. They almost shouted 140 00:07:24,120 --> 00:07:27,520 Speaker 1: eureka live on the tape. So sometimes there really are 141 00:07:27,920 --> 00:07:31,960 Speaker 1: those moments when you know something about the universe. Yeah, 142 00:07:32,000 --> 00:07:33,520 Speaker 1: I guess you. Then you want to be the first 143 00:07:33,560 --> 00:07:38,360 Speaker 1: human to be with like you know something. But it 144 00:07:38,360 --> 00:07:40,880 Speaker 1: does leave your head spinning. This search for truth and 145 00:07:40,960 --> 00:07:44,400 Speaker 1: the cosmos and searching for the idea of how things 146 00:07:44,440 --> 00:07:46,800 Speaker 1: work in the explanation for why things are the way 147 00:07:46,840 --> 00:07:50,600 Speaker 1: they are, including some very interesting questions about whether or 148 00:07:50,640 --> 00:07:54,200 Speaker 1: not things are even spinning in the first place. That's right, 149 00:07:54,240 --> 00:07:56,760 Speaker 1: because we see lots of things spinning in the universe. 150 00:07:56,800 --> 00:07:58,760 Speaker 1: We know the Earth is spinning, and the Earth is 151 00:07:58,760 --> 00:08:01,440 Speaker 1: spinning around the Sun, which is spinning around the center 152 00:08:01,480 --> 00:08:04,480 Speaker 1: of the galaxy, which is itself spinning, which is moving 153 00:08:04,520 --> 00:08:07,320 Speaker 1: around the center of the galaxy cluster. And so naturally, 154 00:08:07,360 --> 00:08:10,120 Speaker 1: as a curious human being, you wonder how far does 155 00:08:10,200 --> 00:08:12,760 Speaker 1: that spinning go? Yes, So to be on the program, 156 00:08:12,760 --> 00:08:22,720 Speaker 1: we'll be asking the question, is the whole universe spinning? So, Daniel, 157 00:08:22,760 --> 00:08:25,880 Speaker 1: how are we spinning? This question is the question it's 158 00:08:25,880 --> 00:08:28,239 Speaker 1: self spinning? Is that what you're saying? This question definitely 159 00:08:28,240 --> 00:08:30,840 Speaker 1: makes my head spin. And it's been one that's been 160 00:08:30,880 --> 00:08:34,440 Speaker 1: debated sort of on the boundary of physics and philosophy 161 00:08:34,520 --> 00:08:37,240 Speaker 1: for a few hundred years. You know, not just the 162 00:08:37,320 --> 00:08:40,840 Speaker 1: question of is our universe spinning? But could it be spinning? 163 00:08:40,880 --> 00:08:43,840 Speaker 1: What does it mean or the whole universe to spin 164 00:08:43,960 --> 00:08:47,880 Speaker 1: spinning relative to what you know? Could you even tell 165 00:08:47,920 --> 00:08:51,120 Speaker 1: if the whole universe was spinning? It's really fascinating question 166 00:08:51,160 --> 00:08:53,920 Speaker 1: that tells us a lot about the nature of space 167 00:08:54,040 --> 00:08:57,760 Speaker 1: itself and what is absolute and what is relative? Right, 168 00:08:57,800 --> 00:09:00,160 Speaker 1: Because I guess you can, you know, ask if ace 169 00:09:00,240 --> 00:09:03,040 Speaker 1: itself is spinning, right, because you know, we know sort 170 00:09:03,040 --> 00:09:05,200 Speaker 1: of spaces kind of a thing that can bend and 171 00:09:05,200 --> 00:09:08,640 Speaker 1: twist and ripple. What if the space itself is turning around? Well, 172 00:09:08,679 --> 00:09:11,600 Speaker 1: you just blew my mind? Man? Did I make your 173 00:09:11,600 --> 00:09:15,319 Speaker 1: head spin? Didn't make you want to eat more chocolate? 174 00:09:16,200 --> 00:09:19,600 Speaker 1: That's always the case. That's a pretty low standard. But yeah, 175 00:09:19,640 --> 00:09:23,080 Speaker 1: you can ask questions like is the stuff in space spinning? 176 00:09:23,559 --> 00:09:27,040 Speaker 1: Is space itself spinning? What would space itself be spinning? 177 00:09:27,160 --> 00:09:31,240 Speaker 1: Relative to? All sorts of really fun, big, mind blowing 178 00:09:31,320 --> 00:09:34,320 Speaker 1: head spinning questions are involved. Well, I guess the question 179 00:09:34,400 --> 00:09:37,600 Speaker 1: we're asking today is the universe spinning. So really we're 180 00:09:37,679 --> 00:09:41,559 Speaker 1: we're asking about the whole shebanging like everything right. Yeah, 181 00:09:41,720 --> 00:09:47,600 Speaker 1: now here's another one, Daniel, Is the multiverse spinning, It's 182 00:09:47,640 --> 00:09:52,440 Speaker 1: definitely spinning money for the Marvel Universe. The Marvel Universe 183 00:09:52,520 --> 00:09:56,640 Speaker 1: is spinning out cash. Yeah, they're shooting out of Spider 184 00:09:56,640 --> 00:10:01,080 Speaker 1: Man's spinning web shooters. If the universe is spinning, and 185 00:10:01,120 --> 00:10:03,360 Speaker 1: that spin is random, then you can imagine there might 186 00:10:03,400 --> 00:10:05,560 Speaker 1: be a whole set of universes which each have their 187 00:10:05,559 --> 00:10:08,360 Speaker 1: own different random spin. And then if we measured our 188 00:10:08,480 --> 00:10:10,760 Speaker 1: universe to have a particular spin, we could ask like, well, 189 00:10:10,800 --> 00:10:13,640 Speaker 1: why this spin not some other spin? You can add 190 00:10:13,640 --> 00:10:16,439 Speaker 1: the multiverse that basically any questions, But then the multiverse 191 00:10:16,480 --> 00:10:18,439 Speaker 1: would would be infinite and it would average out to 192 00:10:18,720 --> 00:10:22,280 Speaker 1: nothing or not. I think this conversation is spinning out 193 00:10:22,280 --> 00:10:27,000 Speaker 1: of control. Dinner, let's get back on track here. Yes, So, 194 00:10:27,040 --> 00:10:29,000 Speaker 1: as usually, we were wondering how many people out there 195 00:10:29,000 --> 00:10:32,360 Speaker 1: had thought about this spinning question, whether or not the 196 00:10:32,400 --> 00:10:35,480 Speaker 1: whole universe is spinning or not, And so Daniel went 197 00:10:35,520 --> 00:10:37,440 Speaker 1: out there into the wilds of the Internet to ask 198 00:10:37,480 --> 00:10:41,800 Speaker 1: people the question, is the whole universe spinning? And thanks 199 00:10:41,840 --> 00:10:45,280 Speaker 1: again to our cadre of volunteers who participate in these 200 00:10:45,320 --> 00:10:48,920 Speaker 1: difficult to answer questions without any chance to do any googling. 201 00:10:49,320 --> 00:10:51,200 Speaker 1: If that sounds fun to you and you'd like to 202 00:10:51,240 --> 00:10:53,200 Speaker 1: hear your voice on the podcast, we would love to 203 00:10:53,240 --> 00:10:56,040 Speaker 1: hear from you, So please don't be shy. It's free, 204 00:10:56,120 --> 00:10:59,520 Speaker 1: it's easy, it's fun right to us. Two questions at 205 00:10:59,679 --> 00:11:02,600 Speaker 1: Daniel and Joge dot com. Think about it for a second. 206 00:11:02,640 --> 00:11:05,880 Speaker 1: Do you feel or think that the universe around you 207 00:11:06,280 --> 00:11:10,079 Speaker 1: is spinning? Here's what people had to say. It wouldn't 208 00:11:10,120 --> 00:11:13,319 Speaker 1: surprise me if the whole universe is spinning because so 209 00:11:13,360 --> 00:11:17,000 Speaker 1: many things are spinning. You know, we're on a spinning 210 00:11:17,120 --> 00:11:21,120 Speaker 1: Earth that, in turn is revolving around the Sun, which 211 00:11:21,200 --> 00:11:24,800 Speaker 1: in turn is revolving around the galaxy, and the galaxy 212 00:11:24,960 --> 00:11:29,280 Speaker 1: itself is spinning, and then our galaxy is probably spinning 213 00:11:29,280 --> 00:11:33,760 Speaker 1: around other galaxies in the local group, which then uh 214 00:11:34,000 --> 00:11:37,880 Speaker 1: itself probably is spinning within the bigger group. Well, I 215 00:11:37,920 --> 00:11:40,640 Speaker 1: feel like we know it's expanding, but I have no 216 00:11:40,679 --> 00:11:43,880 Speaker 1: idea if I've heard that it's spinning or not. Everything 217 00:11:43,880 --> 00:11:46,400 Speaker 1: else in the universe is spinning, so why wouldn't the 218 00:11:46,520 --> 00:11:51,319 Speaker 1: universe spin? Yes, without question, the universe is definitely spinning. 219 00:11:52,360 --> 00:11:56,520 Speaker 1: There's a center of gravity, But I don't think that 220 00:11:56,559 --> 00:12:03,120 Speaker 1: there is a center of gravity across the entire universe. 221 00:12:04,040 --> 00:12:09,880 Speaker 1: I think there are local galactic clusters that rotate um, 222 00:12:09,920 --> 00:12:12,440 Speaker 1: but yeah, because they share a center of gravity, I 223 00:12:12,480 --> 00:12:15,760 Speaker 1: don't think that there's a center of gravity across the universe. 224 00:12:15,800 --> 00:12:18,839 Speaker 1: So I'm going to say, no, it's not. Spin is 225 00:12:18,840 --> 00:12:22,640 Speaker 1: a little relative, right, So in order for it to 226 00:12:22,640 --> 00:12:26,520 Speaker 1: be spinning, it would need to be spinning relative to 227 00:12:26,679 --> 00:12:33,000 Speaker 1: something outside the universe. So that's really a question. Is 228 00:12:33,040 --> 00:12:38,320 Speaker 1: there anything outside the universe for which the universe could 229 00:12:38,360 --> 00:12:41,880 Speaker 1: be spinning? When I think about the universe, I think 230 00:12:41,920 --> 00:12:46,040 Speaker 1: of everything like it's just a word that is sort 231 00:12:46,040 --> 00:12:50,040 Speaker 1: of all encompassing, and I I don't know if if 232 00:12:50,080 --> 00:12:52,600 Speaker 1: we were, if the universe is all encompassing, what would 233 00:12:52,600 --> 00:12:55,720 Speaker 1: it be spinning relative to? Is it that, like space 234 00:12:55,760 --> 00:12:58,200 Speaker 1: itself spinning? Which doesn't make a lot of intuitive sense 235 00:12:58,240 --> 00:13:00,199 Speaker 1: to me. I mean, you could probably figure out if 236 00:13:00,240 --> 00:13:03,120 Speaker 1: it was spinning using I don't know, like the Michaelson 237 00:13:03,160 --> 00:13:06,160 Speaker 1: Morley experiment with like the the the ether or whatever 238 00:13:06,240 --> 00:13:07,719 Speaker 1: you can like test for that kind of a thing. 239 00:13:07,760 --> 00:13:11,800 Speaker 1: I guess if the whole universe was spinning, then everything 240 00:13:12,200 --> 00:13:14,840 Speaker 1: were be moving at the same time. So I don't 241 00:13:14,840 --> 00:13:17,920 Speaker 1: know how we'd be able to tell, but maybe it is. 242 00:13:18,320 --> 00:13:21,360 Speaker 1: All right, a wide range of answers. Some people said yes, 243 00:13:22,480 --> 00:13:26,320 Speaker 1: no hesitation there, yes it's spinning. We got the whole 244 00:13:26,440 --> 00:13:28,800 Speaker 1: range of answers here. We got from yes it's spinning 245 00:13:28,800 --> 00:13:31,720 Speaker 1: to what does that even mean? To how could you 246 00:13:31,800 --> 00:13:34,800 Speaker 1: even tell? It? Really pretty much represents the entire spectrum 247 00:13:34,800 --> 00:13:37,320 Speaker 1: of possible answers, right, even a little bit of a 248 00:13:37,400 --> 00:13:40,640 Speaker 1: maybe there, maybe it's spinning. So it's a fascinating question, 249 00:13:40,800 --> 00:13:43,400 Speaker 1: is the whole universe spinning? And so let's get into 250 00:13:43,400 --> 00:13:47,199 Speaker 1: the particulars of that question. I have questions about it, Daniel, 251 00:13:47,280 --> 00:13:50,360 Speaker 1: could uh could the university spinning? It's a really interesting 252 00:13:50,440 --> 00:13:53,559 Speaker 1: question just to ask, like what does that mean? First 253 00:13:53,600 --> 00:13:56,640 Speaker 1: of all? Right, like could the university spinning? Spinning? Relative 254 00:13:56,720 --> 00:13:59,080 Speaker 1: to what we've talked on this podcast for a while 255 00:13:59,200 --> 00:14:02,480 Speaker 1: about real activity, you know, we talked to Carlo Rovelli, 256 00:14:02,520 --> 00:14:05,240 Speaker 1: for example, about relative motion, and he made a really 257 00:14:05,280 --> 00:14:07,319 Speaker 1: interesting point that we've talked about a few times that 258 00:14:07,400 --> 00:14:10,640 Speaker 1: if you, for example, lived in the universe all by yourself, 259 00:14:10,840 --> 00:14:14,000 Speaker 1: there's nothing else in the universe, then velocity would have 260 00:14:14,040 --> 00:14:18,200 Speaker 1: no meaning. Because velocity is purely a relative quantity. You 261 00:14:18,200 --> 00:14:22,160 Speaker 1: can only be moving relative to other stuff, and so 262 00:14:22,320 --> 00:14:25,400 Speaker 1: in an empty universe, velocity has no meaning. Wait, what 263 00:14:25,480 --> 00:14:28,040 Speaker 1: if the like the universe has a like an extent, 264 00:14:28,200 --> 00:14:29,920 Speaker 1: you know what I mean, like a border or an edge, 265 00:14:29,960 --> 00:14:32,200 Speaker 1: then you could be being relative to that even if 266 00:14:32,240 --> 00:14:35,160 Speaker 1: you were alone in the universe. In our understanding of relativity, 267 00:14:35,240 --> 00:14:38,560 Speaker 1: space is isotropic and homogeneous, meaning there are no special 268 00:14:38,600 --> 00:14:41,960 Speaker 1: locations in space. The kind of cosmology you're talking about 269 00:14:41,960 --> 00:14:45,000 Speaker 1: where there are special locations in space would break a 270 00:14:45,000 --> 00:14:47,520 Speaker 1: lot of the rules that we think we understand, you know, 271 00:14:47,560 --> 00:14:51,000 Speaker 1: like conservation of momentum. And so for now, let's operate 272 00:14:51,040 --> 00:14:53,960 Speaker 1: in a universe that's essentially either infinite in extent or 273 00:14:53,960 --> 00:14:56,960 Speaker 1: where every location in space is the same. So you 274 00:14:57,000 --> 00:14:59,680 Speaker 1: can't be moving just relative to space. You have to 275 00:14:59,680 --> 00:15:02,760 Speaker 1: be moving relative to other stuff in space. So from 276 00:15:02,760 --> 00:15:05,760 Speaker 1: that point of view, you can't ask questions like is 277 00:15:05,800 --> 00:15:10,000 Speaker 1: the whole universe moving? Right now, imagine the universe filled 278 00:15:10,040 --> 00:15:13,280 Speaker 1: with stars and galaxies just like ours. It doesn't make 279 00:15:13,320 --> 00:15:16,000 Speaker 1: sense to ask is all of that stuff moving? Because 280 00:15:16,040 --> 00:15:18,600 Speaker 1: it would have nothing to move relative to if you're 281 00:15:18,600 --> 00:15:21,800 Speaker 1: talking about the whole universe. So from that point of view, 282 00:15:21,840 --> 00:15:25,240 Speaker 1: things like you know, velocity are purely relative. And the 283 00:15:25,320 --> 00:15:28,560 Speaker 1: question then is like, is the same thing true for spin? 284 00:15:29,040 --> 00:15:32,080 Speaker 1: If you were alone in a universe, all by yourself, 285 00:15:32,080 --> 00:15:36,000 Speaker 1: an empty space, could you tell if you were spinning? Right? 286 00:15:36,040 --> 00:15:39,320 Speaker 1: Because velocity, like you're saying, is relative, but acceleration is 287 00:15:39,360 --> 00:15:41,680 Speaker 1: not relative. Right, Like, you could also ask the question 288 00:15:41,760 --> 00:15:44,160 Speaker 1: is the universe accelerating? And that one would have meaning 289 00:15:44,240 --> 00:15:48,120 Speaker 1: right because moving could also apply to acceleration. Yes, velocity 290 00:15:48,200 --> 00:15:52,080 Speaker 1: is purely relative, but acceleration is absolute. Some you can 291 00:15:52,120 --> 00:15:54,640 Speaker 1: measure the acceleration of an object. If you were alone 292 00:15:54,720 --> 00:15:57,040 Speaker 1: in the universe, you could build a little device that 293 00:15:57,080 --> 00:15:59,800 Speaker 1: would tell you whether or not you were accelerating. And 294 00:15:59,800 --> 00:16:01,760 Speaker 1: it's not a complicated device. You could just like have 295 00:16:01,840 --> 00:16:04,480 Speaker 1: a ball in a box and hold it steady. If 296 00:16:04,480 --> 00:16:06,880 Speaker 1: the ball moves towards one side, it means you are 297 00:16:06,920 --> 00:16:11,280 Speaker 1: accelerating in the other direction. That's just how an accelerometer works. 298 00:16:11,680 --> 00:16:13,960 Speaker 1: Or if you're inside a box, you can tell whether 299 00:16:14,000 --> 00:16:17,360 Speaker 1: you're accelerating because you would feel an effective gravity against 300 00:16:17,440 --> 00:16:19,560 Speaker 1: one side or the box. Right, So you can build 301 00:16:19,600 --> 00:16:22,200 Speaker 1: an accelerometer. You don't have to be accelerating relative to 302 00:16:22,240 --> 00:16:25,600 Speaker 1: any other thing. You can be accelerating relative to absolute 303 00:16:25,640 --> 00:16:28,760 Speaker 1: space time. It's interesting the history of how we came 304 00:16:28,800 --> 00:16:31,520 Speaker 1: to these realizations. The first person to think about this 305 00:16:31,640 --> 00:16:36,240 Speaker 1: question whether spin is absolute or relative? You know, can 306 00:16:36,280 --> 00:16:38,360 Speaker 1: you be spinning relative to space or do you have 307 00:16:38,440 --> 00:16:42,280 Speaker 1: to spin relative to other stuff? Was actually Isaac Newton, Right, yeah, 308 00:16:42,400 --> 00:16:44,360 Speaker 1: because where I guess the question is whether or not 309 00:16:44,440 --> 00:16:47,520 Speaker 1: we're spinning or not, and that one can be relative, right, 310 00:16:47,800 --> 00:16:50,040 Speaker 1: or not relative. So that was a question, if you're spinning, 311 00:16:50,120 --> 00:16:52,480 Speaker 1: what are you spinning relative to Are you spinning relative 312 00:16:52,520 --> 00:16:55,240 Speaker 1: to space or are you only spinning relative to other 313 00:16:55,640 --> 00:16:58,760 Speaker 1: stuff out there in the universe? Right, So it's spin 314 00:16:58,840 --> 00:17:02,320 Speaker 1: sort of like acceleration or is it more like velocity? 315 00:17:02,400 --> 00:17:05,040 Speaker 1: And at the time, of course of Newton, Newton thought 316 00:17:05,040 --> 00:17:07,960 Speaker 1: that velocity was absolute, that you were moving relative to 317 00:17:08,200 --> 00:17:11,240 Speaker 1: space itself. But he proposed a really fun thought experiment 318 00:17:11,280 --> 00:17:13,480 Speaker 1: as a way to sort of like measure whether or 319 00:17:13,520 --> 00:17:16,320 Speaker 1: not you're spinning and basically, like you know, a spinometer 320 00:17:16,480 --> 00:17:18,520 Speaker 1: in the same way you can build an accelerometer to 321 00:17:18,560 --> 00:17:21,240 Speaker 1: see if you're accelerating. He thought, let's build an experiment 322 00:17:21,240 --> 00:17:24,200 Speaker 1: that measures whether or not you're spinning. And it's pretty simple. 323 00:17:24,640 --> 00:17:26,840 Speaker 1: You take a bucket of water, and you know the 324 00:17:26,880 --> 00:17:29,160 Speaker 1: surface of the water is flat, and then you start 325 00:17:29,200 --> 00:17:31,240 Speaker 1: spinning the bucket and you spin it sort of along 326 00:17:31,240 --> 00:17:33,199 Speaker 1: its access You could like twist a rope on the 327 00:17:33,240 --> 00:17:35,560 Speaker 1: handle or something like that. Now, what happens, of course, 328 00:17:35,680 --> 00:17:38,240 Speaker 1: is that the bucket starts spinning, and then eventually the 329 00:17:38,280 --> 00:17:40,439 Speaker 1: water gets dragged along by the buckets, and now the 330 00:17:40,480 --> 00:17:42,879 Speaker 1: water is also spinning. And what happens is that the 331 00:17:42,920 --> 00:17:45,479 Speaker 1: water gets pushed up against the sides of the buckets. 332 00:17:45,520 --> 00:17:47,879 Speaker 1: So the surface of the water is no longer flat. 333 00:17:48,040 --> 00:17:50,800 Speaker 1: It's now concave. And so this, he says, is a 334 00:17:50,840 --> 00:17:53,800 Speaker 1: way to measure whether or not you're spinning, because even 335 00:17:53,880 --> 00:17:55,679 Speaker 1: if you're like on the bucket, if you're like an 336 00:17:55,680 --> 00:17:59,040 Speaker 1: ant on the bucket, you can still tell that it's concave. 337 00:17:59,280 --> 00:18:01,359 Speaker 1: Right every it you will agree that the surface of 338 00:18:01,359 --> 00:18:03,560 Speaker 1: the water is now concave. So it's like a way 339 00:18:03,560 --> 00:18:06,159 Speaker 1: to measure the fact that you are spinning, right, It's 340 00:18:06,200 --> 00:18:08,080 Speaker 1: sort of like it's trying to measure whether or not 341 00:18:08,200 --> 00:18:12,040 Speaker 1: there are centripetal acceleration or forces on you because like, 342 00:18:12,080 --> 00:18:15,320 Speaker 1: if you're spinning, something must be causing you to to 343 00:18:15,400 --> 00:18:17,960 Speaker 1: spin to change directions all the time, and that's what 344 00:18:18,119 --> 00:18:22,000 Speaker 1: the centripetal acceleration is. Yes, centripe tol acceleration is pulling 345 00:18:22,000 --> 00:18:25,040 Speaker 1: you towards the center's changing your velocity vector so you're 346 00:18:25,080 --> 00:18:29,639 Speaker 1: moving in a circle. For example, centrifugal acceleration is the 347 00:18:29,720 --> 00:18:32,160 Speaker 1: fictional force that you feel because you're in a non 348 00:18:32,160 --> 00:18:35,000 Speaker 1: inertial reference frame, so that the ant, for example, or 349 00:18:35,000 --> 00:18:37,359 Speaker 1: the water feels that force pushing them outwards. You know, 350 00:18:37,400 --> 00:18:39,040 Speaker 1: the same way. For example, if you are on a 351 00:18:39,080 --> 00:18:42,080 Speaker 1: spaceship out in deep space and it was spinning, you 352 00:18:42,080 --> 00:18:44,680 Speaker 1: would feel an effective gravity. You'd be able to walk 353 00:18:44,720 --> 00:18:47,640 Speaker 1: along the inside of that spinning can as if there 354 00:18:47,680 --> 00:18:51,120 Speaker 1: was gravity. This is one plan for having effective gravity 355 00:18:51,119 --> 00:18:55,600 Speaker 1: and deep spaces. Make your spaceships spin, right. So Newton thought, well, obviously, 356 00:18:55,720 --> 00:18:59,600 Speaker 1: then spin is absolute right that you're spinning relative to 357 00:18:59,760 --> 00:19:02,439 Speaker 1: spa ace, because you can build this thing that measures it. 358 00:19:02,880 --> 00:19:05,040 Speaker 1: And even if you were in the frame of the bucket, 359 00:19:05,040 --> 00:19:07,440 Speaker 1: if you were spinning with the bucket, you could still 360 00:19:07,480 --> 00:19:10,080 Speaker 1: tell that the bucket was spinning. So now imagine that 361 00:19:10,080 --> 00:19:12,520 Speaker 1: bucket in deep and empty space. You should be able 362 00:19:12,520 --> 00:19:15,240 Speaker 1: to tell whether you're spinning or not based on whether 363 00:19:15,280 --> 00:19:18,200 Speaker 1: the water is concave or whether it's flat. So Newton 364 00:19:18,280 --> 00:19:22,200 Speaker 1: was like, I'm very sure that spin is absolute, meaning 365 00:19:22,240 --> 00:19:25,240 Speaker 1: that you could tell maybe if the universe, the whole universe, 366 00:19:25,320 --> 00:19:27,280 Speaker 1: was spinning, right, like if we were just sitting here 367 00:19:27,359 --> 00:19:30,600 Speaker 1: and we felt this in tripital exceloration um, even though 368 00:19:30,640 --> 00:19:33,120 Speaker 1: nothing seemed to be moving, then maybe you could tell 369 00:19:33,160 --> 00:19:36,959 Speaker 1: that the everything was spinning exactly. And if spin is absolute, 370 00:19:37,280 --> 00:19:39,760 Speaker 1: then you could measure the spin of the universe, right, 371 00:19:39,800 --> 00:19:43,359 Speaker 1: because the whole universe could be spinning in space, and 372 00:19:43,400 --> 00:19:46,439 Speaker 1: if that was happening, according to Newton, you could measure it. 373 00:19:46,960 --> 00:19:49,720 Speaker 1: But not everybody agreed with Newton. There was a guy 374 00:19:49,800 --> 00:19:52,120 Speaker 1: named Ernst Mock who came along and said, no, no, no, 375 00:19:52,200 --> 00:19:56,080 Speaker 1: that's not true at all. Spin is purely relative. Motion 376 00:19:56,160 --> 00:19:58,919 Speaker 1: is relative, after all, right, like if you're moving through space, 377 00:19:58,960 --> 00:20:02,840 Speaker 1: that's purely relative. So Mark said, maybe everything is relative, 378 00:20:03,359 --> 00:20:06,879 Speaker 1: maybe all motion in the universe, acceleration and velocity, and 379 00:20:06,880 --> 00:20:10,760 Speaker 1: this is before relativity, right before Einstein said maybe everything 380 00:20:10,840 --> 00:20:13,320 Speaker 1: is relative. And then people said, well, what about the bucket, right, 381 00:20:13,400 --> 00:20:16,320 Speaker 1: the bucket can tell if you're rotating, and Mark said, well, 382 00:20:16,320 --> 00:20:20,120 Speaker 1: the bucket is rotating relative to the stars out there. 383 00:20:20,600 --> 00:20:23,720 Speaker 1: That's why the surface of the bucket gets concave, because 384 00:20:23,720 --> 00:20:26,480 Speaker 1: it's rotating not relative to space, but to the stars 385 00:20:26,520 --> 00:20:29,119 Speaker 1: out there in the universe. That doesn't make a lot 386 00:20:29,119 --> 00:20:30,800 Speaker 1: of sense. It doesn't make a lot of sense to 387 00:20:30,840 --> 00:20:33,160 Speaker 1: me either. But remember, at the time, people didn't really 388 00:20:33,240 --> 00:20:36,280 Speaker 1: understand the notion of space and time and relativity, and 389 00:20:36,320 --> 00:20:38,080 Speaker 1: these questions were sort of up in the air, you know. 390 00:20:38,080 --> 00:20:41,520 Speaker 1: People wanted to know, for example, if velocity is relative, 391 00:20:41,560 --> 00:20:45,119 Speaker 1: as we all accept, then why isn't acceleration relative? Like 392 00:20:45,160 --> 00:20:47,919 Speaker 1: you said it earlier that velocity is relative but acceleration 393 00:20:48,000 --> 00:20:50,600 Speaker 1: is not. But why not? And at the time people 394 00:20:50,680 --> 00:20:53,520 Speaker 1: didn't understand, and so this was sort of a beautiful 395 00:20:53,560 --> 00:20:56,520 Speaker 1: idea to say, well, maybe everything is actually relative, and 396 00:20:56,600 --> 00:20:59,040 Speaker 1: the reason that the surface of the bucket gets concave 397 00:20:59,200 --> 00:21:02,560 Speaker 1: is somehow because of the distant stars. And on the 398 00:21:02,600 --> 00:21:04,639 Speaker 1: other side, people say, well, that's ridiculous, Like, are you 399 00:21:04,680 --> 00:21:07,040 Speaker 1: saying that if you spun a bucket in empty space 400 00:21:07,320 --> 00:21:10,280 Speaker 1: that it would stay flat? Right? He said, absolutely, If 401 00:21:10,280 --> 00:21:12,600 Speaker 1: you spin your bucket and then you start removing the 402 00:21:12,720 --> 00:21:15,760 Speaker 1: stars out there in the universe that the surface of 403 00:21:15,760 --> 00:21:18,760 Speaker 1: the bucket would go from concave to flat, that somehow 404 00:21:19,080 --> 00:21:22,119 Speaker 1: those distant, distant stars are telling the bucket surface what 405 00:21:22,240 --> 00:21:24,000 Speaker 1: to do. I feel like MOK should have stuck to 406 00:21:24,080 --> 00:21:29,399 Speaker 1: like sound research, maybe not trying to do astronomy here. 407 00:21:29,400 --> 00:21:31,040 Speaker 1: But I guess you're saying that's kind of the thinking 408 00:21:31,080 --> 00:21:33,600 Speaker 1: at the time, like maybe if you sort of like 409 00:21:33,720 --> 00:21:36,399 Speaker 1: removed a reference frame, and maybe that's kind of what 410 00:21:36,400 --> 00:21:38,199 Speaker 1: he was getting at. It's like, if you remove the 411 00:21:38,240 --> 00:21:41,960 Speaker 1: reference frame of the stars, then somehow, um, maybe you 412 00:21:42,040 --> 00:21:45,600 Speaker 1: lose all relativity. Yeah. Max said that spinning is relative. 413 00:21:45,640 --> 00:21:48,000 Speaker 1: If you're not spinning relative to something else, then you're 414 00:21:48,040 --> 00:21:51,320 Speaker 1: not spinning. Spinning in an empty universe has no meaning 415 00:21:51,320 --> 00:21:53,000 Speaker 1: that you could never tell. You know that if you 416 00:21:53,040 --> 00:21:55,119 Speaker 1: were in an empty universe and I started to spin you, 417 00:21:55,119 --> 00:21:58,080 Speaker 1: you wouldn't feel your arms get pushed out towards the side. 418 00:21:58,119 --> 00:22:00,200 Speaker 1: If you build a spaceship and spun it in an 419 00:22:00,200 --> 00:22:04,280 Speaker 1: empty universe, you wouldn't feel effective gravity that comes somehow 420 00:22:04,400 --> 00:22:07,680 Speaker 1: from the distant stars that are defining a reference frame. 421 00:22:07,760 --> 00:22:10,440 Speaker 1: And this was a beautiful idea, and even Einstein liked that. 422 00:22:10,480 --> 00:22:13,120 Speaker 1: Einstein thought Oh, this sounds really nice, and he tried 423 00:22:13,240 --> 00:22:16,359 Speaker 1: really hard to work it into his theory of relativity, 424 00:22:16,400 --> 00:22:18,959 Speaker 1: because I think the idea was that motion is relative, right, 425 00:22:19,000 --> 00:22:21,640 Speaker 1: like everything is relative. So Einstein basically came up later 426 00:22:21,680 --> 00:22:24,520 Speaker 1: and said, actually, turns out Newton is wrong and also 427 00:22:24,680 --> 00:22:27,840 Speaker 1: Mock is wrong. They're both wrong in slightly different ways. 428 00:22:28,080 --> 00:22:30,520 Speaker 1: All right, Well, let's get into how Einstein proved them 429 00:22:30,520 --> 00:22:33,720 Speaker 1: wrong and whether or not the whole universe is spinning, 430 00:22:34,080 --> 00:22:36,080 Speaker 1: because my head is spinning a little bit right now, 431 00:22:36,119 --> 00:22:39,480 Speaker 1: and I kind of made a little break, so we'll 432 00:22:39,520 --> 00:22:54,359 Speaker 1: be right back. All right, we're asking the question is 433 00:22:54,400 --> 00:22:57,359 Speaker 1: the whole universe spinning? I am getting a little dizzy 434 00:22:57,400 --> 00:23:00,480 Speaker 1: just thinking about and talking about this question. And where 435 00:23:00,480 --> 00:23:03,359 Speaker 1: we left off was that Einstein looked at Newton and 436 00:23:03,359 --> 00:23:06,000 Speaker 1: then he looked at another researcher back in the day, 437 00:23:06,000 --> 00:23:09,520 Speaker 1: and he said, um, you're both wrong. Actually, maybe spinning 438 00:23:10,000 --> 00:23:14,440 Speaker 1: is also relative. So Einstein said, definitely, Newton is wrong, 439 00:23:14,640 --> 00:23:18,359 Speaker 1: because Newton said that all motion is absolute, that space 440 00:23:18,480 --> 00:23:22,000 Speaker 1: is like its own absolute frame, and velocity is absolute, 441 00:23:22,280 --> 00:23:24,760 Speaker 1: that in an empty universe and object moving in his 442 00:23:24,840 --> 00:23:27,600 Speaker 1: train line, you could somehow measure its velocity relative to 443 00:23:27,640 --> 00:23:31,359 Speaker 1: absolute space. So Einstein said, no, that's ridiculous. There is 444 00:23:31,400 --> 00:23:35,080 Speaker 1: no preferred location in space, There is no preferred velocity 445 00:23:35,160 --> 00:23:37,560 Speaker 1: in space. That doesn't make any sense. And he built 446 00:23:37,560 --> 00:23:40,200 Speaker 1: that into his theory of relativity. But he also said 447 00:23:40,240 --> 00:23:42,560 Speaker 1: that Mack was wrong because Mak wanted to go even 448 00:23:42,560 --> 00:23:46,520 Speaker 1: further and say, well, even acceleration is relative, and Einstein 449 00:23:46,560 --> 00:23:48,920 Speaker 1: liked that idea, but he found that it didn't actually work. 450 00:23:49,480 --> 00:23:52,760 Speaker 1: And so what Einstein says is that space is relative. 451 00:23:52,960 --> 00:23:54,640 Speaker 1: And we've talked up on the podcast a few times 452 00:23:54,680 --> 00:23:58,280 Speaker 1: about how time is relative. Also different observers in the 453 00:23:58,400 --> 00:24:01,959 Speaker 1: universe feel timed differently. But when you put the two together, 454 00:24:02,240 --> 00:24:06,560 Speaker 1: space time, you actually do get something absolute. Einstein didn't 455 00:24:06,560 --> 00:24:10,240 Speaker 1: actually like calling his theory relativity theory because he thought 456 00:24:10,240 --> 00:24:12,920 Speaker 1: it oversawled the relativity aspect of it. He wanted to 457 00:24:12,960 --> 00:24:15,919 Speaker 1: call it invariance theory. But anyway, what he found was 458 00:24:15,960 --> 00:24:19,199 Speaker 1: that space is relative and time is relative, but that 459 00:24:19,440 --> 00:24:23,760 Speaker 1: space time together had some absolutes in it that lets 460 00:24:23,760 --> 00:24:28,840 Speaker 1: you measure whether something is accelerating, and spinning counts as accelerating. 461 00:24:29,160 --> 00:24:33,160 Speaker 1: So acceleration and spin are absolute, but velocity is relative. 462 00:24:33,920 --> 00:24:36,439 Speaker 1: I guess it sort of maybe depends on your definition, right, 463 00:24:36,480 --> 00:24:40,360 Speaker 1: Like is spinning motion also motion, or is spinning motion 464 00:24:41,160 --> 00:24:43,600 Speaker 1: like something that's not motioned, you know what I mean? 465 00:24:43,640 --> 00:24:47,560 Speaker 1: Like maybe you're saying, you know, spinning involves acceleration, and 466 00:24:47,600 --> 00:24:50,320 Speaker 1: therefore it's not sort of the same as moving with 467 00:24:50,359 --> 00:24:55,000 Speaker 1: a constant velocity exactly. Spinning is definitely a kind of acceleration. 468 00:24:55,400 --> 00:24:58,800 Speaker 1: So then the question really is is acceleration absolute. If 469 00:24:58,840 --> 00:25:01,840 Speaker 1: acceleration is absolut if you can measure acceleration out in 470 00:25:01,920 --> 00:25:05,439 Speaker 1: deep space, that means that spinning is absolute, that you 471 00:25:05,440 --> 00:25:08,960 Speaker 1: could also measure spin in deep space. And so Einstein's 472 00:25:08,960 --> 00:25:12,000 Speaker 1: theory of relativity shows us that velocity is relative, but 473 00:25:12,080 --> 00:25:15,880 Speaker 1: that acceleration is absolute. That you can tell if an 474 00:25:15,880 --> 00:25:19,080 Speaker 1: object is accelerating, which also means you can tell if 475 00:25:19,119 --> 00:25:21,399 Speaker 1: it's spinning, right, which means that if you even if 476 00:25:21,400 --> 00:25:23,679 Speaker 1: you were alone in the universe, you can still get dizzy. 477 00:25:23,840 --> 00:25:25,800 Speaker 1: You can get dizzy in an empty universe. And we've 478 00:25:25,800 --> 00:25:28,359 Speaker 1: seen this other times when we've talked about Einstein's theory 479 00:25:28,400 --> 00:25:31,760 Speaker 1: of relativity and spin. Because Einstein's theory, for example, predicts 480 00:25:31,760 --> 00:25:34,840 Speaker 1: a difference between the gravity of an object that's spinning 481 00:25:34,880 --> 00:25:37,679 Speaker 1: a gravity of an object that's not spinning. A spinning 482 00:25:37,680 --> 00:25:41,440 Speaker 1: object has this weird effect frame dragging, where like drags 483 00:25:41,560 --> 00:25:44,840 Speaker 1: space along behind it a little bit. And Newton doesn't 484 00:25:44,880 --> 00:25:47,320 Speaker 1: predict that because Newton says there's no difference between the 485 00:25:47,320 --> 00:25:50,400 Speaker 1: gravity of a spinning object and a non spinning object, 486 00:25:50,440 --> 00:25:53,360 Speaker 1: and that wouldn't make any sense if spinning was purely relative. Right, 487 00:25:53,400 --> 00:25:56,359 Speaker 1: So spinning objects have a different gravitational effect, and therefore 488 00:25:56,400 --> 00:25:58,840 Speaker 1: you must be able to tell the difference between spinning 489 00:25:58,840 --> 00:26:01,760 Speaker 1: and non spinning objects, right, But I wonder if that 490 00:26:01,920 --> 00:26:04,159 Speaker 1: is that something. I guess that's just kind of built 491 00:26:04,200 --> 00:26:07,280 Speaker 1: into the laws of the universe that we that we 492 00:26:07,320 --> 00:26:09,720 Speaker 1: can tell, Like why does the universe draw the line 493 00:26:09,760 --> 00:26:14,119 Speaker 1: between velocity and acceleration, because you know, mathematically, it's just 494 00:26:14,160 --> 00:26:19,040 Speaker 1: like one derivative over. It is just one derivative like 495 00:26:19,040 --> 00:26:21,600 Speaker 1: it could have been acceleration is also invariant, but then 496 00:26:21,800 --> 00:26:25,240 Speaker 1: the derivative of acceleration the next one over, is not relative. 497 00:26:25,480 --> 00:26:27,600 Speaker 1: It does seem sort of arbitrary to like draw the 498 00:26:27,640 --> 00:26:30,000 Speaker 1: line at the first derivative and not the second derivative. 499 00:26:30,040 --> 00:26:31,760 Speaker 1: And there are a lot of really deep ideas here. 500 00:26:31,840 --> 00:26:34,399 Speaker 1: One of them has to do with symmetry and conservation laws. 501 00:26:34,720 --> 00:26:37,160 Speaker 1: We'll talk about that in an episode coming up soon 502 00:26:37,480 --> 00:26:39,480 Speaker 1: on Nuther's Theorem. I think the best way to think 503 00:26:39,480 --> 00:26:41,639 Speaker 1: about it is to think about what is invariant, what 504 00:26:41,840 --> 00:26:44,920 Speaker 1: is preserved in the universe. The reason, for example, that 505 00:26:44,960 --> 00:26:48,159 Speaker 1: you can tell that something is accelerating versus something is 506 00:26:48,200 --> 00:26:51,520 Speaker 1: not is because of their path through space time. You know, 507 00:26:51,560 --> 00:26:53,879 Speaker 1: this has to do with things like free fall. Right, 508 00:26:53,920 --> 00:26:56,840 Speaker 1: if you are just moving through space without accelerating, you 509 00:26:56,880 --> 00:26:59,720 Speaker 1: don't feel any forces, which you're effectively doing is making 510 00:26:59,720 --> 00:27:03,359 Speaker 1: a straight line through space time. Like your path through 511 00:27:03,480 --> 00:27:06,760 Speaker 1: space time is just a straight line. If you're accelerating, 512 00:27:06,760 --> 00:27:09,439 Speaker 1: you like burn your rocket. If you're being pushed by something, 513 00:27:09,640 --> 00:27:12,520 Speaker 1: then you make a curve in spacetime. So the reason 514 00:27:12,520 --> 00:27:14,840 Speaker 1: that you can tell whether something is accelerating or not 515 00:27:15,040 --> 00:27:18,639 Speaker 1: is because everybody agrees. All observers agree whether or not 516 00:27:18,680 --> 00:27:21,000 Speaker 1: you're making a straight line in space time or a 517 00:27:21,040 --> 00:27:23,520 Speaker 1: curve in spacetime. That's what it means to say that 518 00:27:23,600 --> 00:27:26,919 Speaker 1: spacetime itself is absolute, that the universe can tell the 519 00:27:26,920 --> 00:27:31,560 Speaker 1: difference between straight paths and spacetime and curved paths in spacetime. Well, 520 00:27:31,600 --> 00:27:33,199 Speaker 1: I guess that's kind of what I mean, like, you know, 521 00:27:33,240 --> 00:27:36,000 Speaker 1: you said, it's all sort of depends or it's all 522 00:27:36,040 --> 00:27:38,960 Speaker 1: because of some symmetry in the universe. But then like, 523 00:27:39,000 --> 00:27:41,119 Speaker 1: what if the universe they didn't have those symmetries, or 524 00:27:41,119 --> 00:27:43,480 Speaker 1: what if we lived in another universe without those symmetries, 525 00:27:43,520 --> 00:27:48,760 Speaker 1: would those RULs be different? Or is that invariant about 526 00:27:49,240 --> 00:27:53,240 Speaker 1: the velocity and acceleration kind of baked into math itself. 527 00:27:53,280 --> 00:27:56,000 Speaker 1: It's not baked in the math. You could construct cosmologies 528 00:27:56,040 --> 00:27:57,960 Speaker 1: where things were different. This is the universe that we 529 00:27:58,080 --> 00:28:00,760 Speaker 1: find ourselves in. These are the rule that we discover. 530 00:28:01,280 --> 00:28:02,960 Speaker 1: You know. It's sort of like asking the question and 531 00:28:03,000 --> 00:28:05,720 Speaker 1: why is momentum conserved? And the answer is space is 532 00:28:05,760 --> 00:28:08,440 Speaker 1: the same everywhere? All right, well, why is this space 533 00:28:08,480 --> 00:28:11,640 Speaker 1: the same everywhere? It's not required by mathematics. You could 534 00:28:11,720 --> 00:28:14,280 Speaker 1: have a universe where the rules of physics vary from 535 00:28:14,280 --> 00:28:16,960 Speaker 1: place to place. We just don't seem to have that universe. 536 00:28:17,080 --> 00:28:18,920 Speaker 1: So this is sort of like a discovery of ours. 537 00:28:19,000 --> 00:28:22,040 Speaker 1: The universe seems to obey this principle, and these are 538 00:28:22,040 --> 00:28:25,160 Speaker 1: the consequences of that principle. Why does it obey this principle? 539 00:28:25,480 --> 00:28:28,000 Speaker 1: We don't know, But we've discovered it. It's sort of 540 00:28:28,040 --> 00:28:31,360 Speaker 1: like saying, okay, the speed of light is invariant for everybody. 541 00:28:31,359 --> 00:28:33,600 Speaker 1: Everybody measures the speed of light to be the same. Why, 542 00:28:33,800 --> 00:28:36,680 Speaker 1: we don't know, but here are the consequences of it. 543 00:28:36,760 --> 00:28:39,720 Speaker 1: This is the invariance that Einstein discovered that space is 544 00:28:39,760 --> 00:28:43,200 Speaker 1: not invariant, but space time is. You know. Another way 545 00:28:43,240 --> 00:28:45,360 Speaker 1: to think about these paths is to think about like, 546 00:28:45,400 --> 00:28:47,720 Speaker 1: you know, imagine how you get from your house to 547 00:28:47,800 --> 00:28:50,240 Speaker 1: your work. Somebody could draw like a set of axes X, 548 00:28:50,360 --> 00:28:52,800 Speaker 1: y Z and say Joge gets from his house to 549 00:28:52,880 --> 00:28:55,160 Speaker 1: his work and from this coordinate to that coordinate. And 550 00:28:55,280 --> 00:28:56,880 Speaker 1: somebody else could come along and say, well, I have 551 00:28:56,880 --> 00:28:59,760 Speaker 1: a totally different set of coordinates for Jorges path from 552 00:29:00,040 --> 00:29:02,680 Speaker 1: him to work, and those are totally different coordinates, but 553 00:29:02,760 --> 00:29:05,960 Speaker 1: doesn't matter. And it doesn't matter because the path itself 554 00:29:06,160 --> 00:29:08,240 Speaker 1: is the same. The two observers would look at the 555 00:29:08,240 --> 00:29:10,160 Speaker 1: path and say, oh, it's a straight line or no, 556 00:29:10,240 --> 00:29:12,320 Speaker 1: it's a wiggle because he stops at the fridge on 557 00:29:12,360 --> 00:29:15,080 Speaker 1: the way from his bed to his cartooning studio. Right, 558 00:29:15,200 --> 00:29:17,480 Speaker 1: So people agree about the shape of the path even 559 00:29:17,520 --> 00:29:20,760 Speaker 1: if they don't agree about the actual coordinates. That's what 560 00:29:20,800 --> 00:29:23,600 Speaker 1: it means that space time, your path through space time 561 00:29:24,240 --> 00:29:29,240 Speaker 1: is absolute, even if your coordinates are arbitrary. Well sometimes 562 00:29:29,240 --> 00:29:33,200 Speaker 1: I work from bed. Even everyone would agree that it's 563 00:29:33,240 --> 00:29:35,800 Speaker 1: a short community. Yeah, exactly. If your path is a point, 564 00:29:35,920 --> 00:29:38,840 Speaker 1: then everybody would agree. Yeah, that's the whole point of 565 00:29:38,840 --> 00:29:41,720 Speaker 1: being a cartoonist is to live in a point. But 566 00:29:41,760 --> 00:29:43,520 Speaker 1: I think what you're saying is that you know, it's 567 00:29:43,520 --> 00:29:45,760 Speaker 1: sort of baked into the laws of at least this 568 00:29:45,880 --> 00:29:48,520 Speaker 1: universe that we live in, that you can't tell if 569 00:29:48,560 --> 00:29:51,160 Speaker 1: something is spinning, Like it's not something that you can hid, 570 00:29:51,280 --> 00:29:54,040 Speaker 1: or it's not something that you can like maybe never tell. 571 00:29:54,200 --> 00:29:56,320 Speaker 1: But the question we're asking today is whether the whole 572 00:29:56,600 --> 00:29:59,840 Speaker 1: universe is spinning, which kind of makes me wonder, like 573 00:30:00,040 --> 00:30:02,600 Speaker 1: feel like, now it could go either way, because yes, 574 00:30:02,640 --> 00:30:04,800 Speaker 1: you can tell if something is spinning in the universe, 575 00:30:04,920 --> 00:30:07,920 Speaker 1: but what if the universe itself is spinning? Could you tell? Here? 576 00:30:07,920 --> 00:30:09,400 Speaker 1: I think we have to be careful about what we 577 00:30:09,480 --> 00:30:12,120 Speaker 1: mean by the universe. And I'm talking now about the 578 00:30:12,160 --> 00:30:14,920 Speaker 1: matter in the universe. Like I take all the stuff, 579 00:30:14,920 --> 00:30:18,240 Speaker 1: the galaxies, the dust, the gas, the dark matter, is 580 00:30:18,280 --> 00:30:21,240 Speaker 1: all of that stuff spinning and that here it's spinning 581 00:30:21,280 --> 00:30:25,320 Speaker 1: relative to space time. Spacetime itself can that spin? Like, well, 582 00:30:25,360 --> 00:30:28,480 Speaker 1: what would that be spinning relative too? There's no external 583 00:30:28,520 --> 00:30:32,000 Speaker 1: metric for spacetime itself to spin. So we're talking about, like, 584 00:30:32,040 --> 00:30:34,440 Speaker 1: you know, the Earth is spinning, is it possible that 585 00:30:34,520 --> 00:30:37,479 Speaker 1: everything else is also spinning in that same way that 586 00:30:37,520 --> 00:30:39,719 Speaker 1: the Earth is spinning? Oh? I see You're you've been 587 00:30:39,760 --> 00:30:42,640 Speaker 1: spinning this question the whole time, Daniel. You're really asking 588 00:30:42,800 --> 00:30:45,480 Speaker 1: is the whole stuff in the universe spinning? You're not 589 00:30:45,560 --> 00:30:48,200 Speaker 1: asking if the universe is spinning. Well, it depends on 590 00:30:48,280 --> 00:30:51,320 Speaker 1: whether you're including space time in that spin. And I 591 00:30:51,320 --> 00:30:54,080 Speaker 1: would say it doesn't make sense for space time itself 592 00:30:54,120 --> 00:30:58,400 Speaker 1: to spin, but stuff in space time can spin relative 593 00:30:58,600 --> 00:31:01,160 Speaker 1: to space time. Well, I guess maybe let's explore that 594 00:31:01,200 --> 00:31:03,240 Speaker 1: a little bit. Like we've talked about space being a thing, 595 00:31:03,440 --> 00:31:05,560 Speaker 1: How do you know it's not spinning? It could be 596 00:31:05,640 --> 00:31:08,720 Speaker 1: spinning even if it's not relative to anything. Right, the 597 00:31:08,760 --> 00:31:11,040 Speaker 1: same way that we talked about expansion of spacetime, we 598 00:31:11,080 --> 00:31:14,560 Speaker 1: don't say that spacetime is expanding into something else. We 599 00:31:14,640 --> 00:31:17,920 Speaker 1: only have intrinsic measurements. We are in spacetime. There's nothing 600 00:31:18,000 --> 00:31:20,400 Speaker 1: outside of space time to measure, so we can only 601 00:31:20,440 --> 00:31:24,800 Speaker 1: measure internally. Right, So we say spaces expanding, people ask 602 00:31:24,840 --> 00:31:27,600 Speaker 1: what is it expanding into? Well, it's not expanding into anything. 603 00:31:27,640 --> 00:31:31,760 Speaker 1: It's just increasing the relative distances between stuff in space. 604 00:31:32,200 --> 00:31:34,800 Speaker 1: So in the same way, you can't really ask what 605 00:31:35,000 --> 00:31:38,920 Speaker 1: is spacetime rotating in It's not in anything. It just 606 00:31:39,000 --> 00:31:41,840 Speaker 1: sort of is. And so there's no sense in which 607 00:31:41,840 --> 00:31:44,440 Speaker 1: space time could spin. But I thought you were going 608 00:31:44,480 --> 00:31:46,560 Speaker 1: the other way, because you know, you can say that 609 00:31:46,680 --> 00:31:50,000 Speaker 1: space is expanding, but it's not expanding relative to anything. 610 00:31:50,320 --> 00:31:53,000 Speaker 1: Couldn't I just say spacetime is spinning, but it's just 611 00:31:53,040 --> 00:31:55,320 Speaker 1: not spinning relative to anything. Then what does that mean 612 00:31:55,360 --> 00:31:56,920 Speaker 1: for it to be spinning? What does it mean for 613 00:31:56,960 --> 00:32:01,360 Speaker 1: its expanding nothingness? It means that the distances between stuff 614 00:32:01,400 --> 00:32:03,760 Speaker 1: are getting larger, right, But what does it mean for 615 00:32:04,240 --> 00:32:07,200 Speaker 1: space time itself as a whole to spin? You can 616 00:32:07,240 --> 00:32:10,000 Speaker 1: tell whether's something is spinning relative to space time same 617 00:32:10,040 --> 00:32:12,440 Speaker 1: way you can tell whether you know distances are growing, 618 00:32:12,800 --> 00:32:15,600 Speaker 1: but you can't tell whether spacetime itself is spinning. You 619 00:32:15,680 --> 00:32:17,720 Speaker 1: could maybe, like maybe if I was alone in the 620 00:32:17,800 --> 00:32:20,520 Speaker 1: universe and I got dizzy, you know what I mean? 621 00:32:20,520 --> 00:32:22,080 Speaker 1: Like I guess what I'm wondering is, could there be 622 00:32:22,120 --> 00:32:26,000 Speaker 1: like an inherent centripital acceleration to the universe. I think 623 00:32:26,040 --> 00:32:29,560 Speaker 1: it's possible. Mathematically, there is always an ambiguity there, even 624 00:32:29,600 --> 00:32:32,320 Speaker 1: in the case of expansion, because general relativity has this 625 00:32:32,440 --> 00:32:35,280 Speaker 1: weird difficulty by talking about the velocities of things that 626 00:32:35,280 --> 00:32:38,719 Speaker 1: are very far away, you always define either relative velocities 627 00:32:38,840 --> 00:32:42,240 Speaker 1: or velocities relative to space. And so probably there's a 628 00:32:42,280 --> 00:32:45,320 Speaker 1: way you could construct a universe that had a rotating 629 00:32:45,400 --> 00:32:49,680 Speaker 1: space time that had an inherent built in centrifugal acceleration. 630 00:32:50,000 --> 00:32:52,600 Speaker 1: You know, for example, a curvature of space would give 631 00:32:52,640 --> 00:32:55,240 Speaker 1: you that effect if space was curved in such a 632 00:32:55,240 --> 00:32:58,920 Speaker 1: way that you effectively felt a negative gravity. And there 633 00:32:58,960 --> 00:33:02,080 Speaker 1: are some folks out there argue that dark energy may 634 00:33:02,200 --> 00:33:06,200 Speaker 1: partially be due to some like inherent and trifugal force 635 00:33:06,600 --> 00:33:09,880 Speaker 1: due to the rotation of space time itself, rather than 636 00:33:10,040 --> 00:33:14,880 Speaker 1: some expansion of space. WHOA wait, so like the space 637 00:33:14,920 --> 00:33:16,960 Speaker 1: and could be spinning and it might be the answer 638 00:33:17,040 --> 00:33:19,680 Speaker 1: to dark energy. That's one thing people were probably and 639 00:33:19,680 --> 00:33:22,000 Speaker 1: we'll talk about how people use type one a supernova 640 00:33:22,080 --> 00:33:24,200 Speaker 1: to try to answer that question. You a little bit 641 00:33:24,200 --> 00:33:26,960 Speaker 1: when we talk about how to measure whether space is spinning. 642 00:33:27,000 --> 00:33:29,120 Speaker 1: All right, we'll leave that for another episode, but I 643 00:33:29,120 --> 00:33:31,880 Speaker 1: guess in this episode we are now shifting the question too. 644 00:33:32,400 --> 00:33:36,560 Speaker 1: Is everything in the universe in spacetime it's self spinning, 645 00:33:36,600 --> 00:33:39,160 Speaker 1: because you know, it could be spinning, right Like, like 646 00:33:39,200 --> 00:33:41,400 Speaker 1: you said earlier, the Earth is spinning, and we're spinning 647 00:33:41,440 --> 00:33:43,920 Speaker 1: around the Sun, and the Sun is spinning around the 648 00:33:43,960 --> 00:33:47,600 Speaker 1: gaxy and the GALSSI. It's probably spinning around some larger 649 00:33:47,800 --> 00:33:50,880 Speaker 1: cluster of galaxies, and that could also be spinning relative 650 00:33:50,960 --> 00:33:54,200 Speaker 1: to other clusters. You know, is everything may be spinning. 651 00:33:54,280 --> 00:33:56,800 Speaker 1: It's a really fun question, and what we expect, what 652 00:33:56,920 --> 00:34:00,480 Speaker 1: physics predicts, is sort of counterintuitive because on one hand, 653 00:34:00,520 --> 00:34:02,320 Speaker 1: we see that everything is spinning, as you say, the 654 00:34:02,320 --> 00:34:04,360 Speaker 1: Earth is spinning, of the galaxy is spinning, but we 655 00:34:04,400 --> 00:34:08,359 Speaker 1: don't actually expect, on very very large scales for all 656 00:34:08,400 --> 00:34:10,200 Speaker 1: the stuff in the universe to be spinning. That if 657 00:34:10,239 --> 00:34:12,560 Speaker 1: you added up all the stuff in the universe, we 658 00:34:12,640 --> 00:34:15,920 Speaker 1: actually predict that it should have zero spin, right because 659 00:34:15,960 --> 00:34:20,480 Speaker 1: it seems kind of implausible almost that everything would not 660 00:34:20,680 --> 00:34:23,960 Speaker 1: to be spinning, that it would be sort of standing still. 661 00:34:24,080 --> 00:34:27,480 Speaker 1: It doesn't. It's actually a very specific prediction of inflation. Remember, 662 00:34:27,520 --> 00:34:30,319 Speaker 1: inflation is this prediction that the universe started out much 663 00:34:30,400 --> 00:34:33,279 Speaker 1: much denser, much much more compact, and then spread out 664 00:34:33,320 --> 00:34:36,000 Speaker 1: and expanded and blew out, and that all the structure 665 00:34:36,040 --> 00:34:38,319 Speaker 1: we see in the universe comes from like the little 666 00:34:38,440 --> 00:34:41,279 Speaker 1: quantum fluctuations in density from the early universe. And it's 667 00:34:41,280 --> 00:34:44,560 Speaker 1: that expansion itself that we think would have killed effectively 668 00:34:44,560 --> 00:34:48,040 Speaker 1: any rotation. Remember what happens when you're spinning. If you're 669 00:34:48,040 --> 00:34:50,279 Speaker 1: like on ice in your figure skater, if you pull 670 00:34:50,320 --> 00:34:53,240 Speaker 1: your arms towards yourself, then you start to spin faster. 671 00:34:53,560 --> 00:34:55,520 Speaker 1: And that's why, for example, the Earth is spinning because 672 00:34:55,560 --> 00:34:57,360 Speaker 1: it started out from a cloud of stuff that was 673 00:34:57,560 --> 00:35:00,239 Speaker 1: very gently spinning and then collapsed, and the is now 674 00:35:00,280 --> 00:35:03,879 Speaker 1: spinning faster. But expansion has the opposite effect. So as 675 00:35:03,880 --> 00:35:06,960 Speaker 1: the universe expands, we expected to spin less and less. 676 00:35:07,520 --> 00:35:10,440 Speaker 1: Because inflation expanded the universe by like ten to the 677 00:35:10,560 --> 00:35:14,439 Speaker 1: thirty than any tiny random rotation of that initial blob 678 00:35:14,480 --> 00:35:17,040 Speaker 1: of stuff, we would expect that to be effectively zeroed 679 00:35:17,040 --> 00:35:20,040 Speaker 1: out by inflation. Right, I guess maybe I'm getting a 680 00:35:20,040 --> 00:35:22,920 Speaker 1: little confused here because of what we're actually asking, Like, 681 00:35:23,080 --> 00:35:25,680 Speaker 1: I guess, are we asking whether all this stuff in 682 00:35:25,719 --> 00:35:30,720 Speaker 1: the universe has a zero or non zero average spin? 683 00:35:30,840 --> 00:35:32,360 Speaker 1: Do you know what I mean? Like, for sure I 684 00:35:32,400 --> 00:35:34,759 Speaker 1: can spin in my chair here, and the Earth is 685 00:35:34,920 --> 00:35:37,279 Speaker 1: for sure spinning, and the Sun is definitely spinning, and 686 00:35:37,320 --> 00:35:40,440 Speaker 1: the galaxy and the galaxy clusters are definitely moving relative 687 00:35:40,480 --> 00:35:43,239 Speaker 1: to other things. I guess is the question, like, if 688 00:35:43,239 --> 00:35:45,840 Speaker 1: you average out everything, all the stuff in the universe, 689 00:35:46,200 --> 00:35:48,440 Speaker 1: does it have a spin to it or does it 690 00:35:48,480 --> 00:35:51,480 Speaker 1: all cancel out to exactly zero? Is that kind of 691 00:35:51,480 --> 00:35:54,200 Speaker 1: what we're really asking here? Yeah, draw line through space 692 00:35:54,200 --> 00:35:56,759 Speaker 1: and measure the spin relative to that line, and then 693 00:35:56,840 --> 00:36:00,800 Speaker 1: ask is that overall spinning all the stuff in the universe? 694 00:36:01,360 --> 00:36:03,480 Speaker 1: Is that zero or not? Right? Sort of like if 695 00:36:03,480 --> 00:36:05,799 Speaker 1: you have a snow globe, maybe I'm thinking, you know, 696 00:36:06,120 --> 00:36:08,840 Speaker 1: you can have all the snowflakes inside moving and twirling 697 00:36:08,960 --> 00:36:12,399 Speaker 1: and looking chaotic, but overall you can sort of tell 698 00:36:12,480 --> 00:36:15,480 Speaker 1: whether or not this stuff in it is spinning relative 699 00:36:15,560 --> 00:36:18,200 Speaker 1: to the globe. What you're saying is that it maybe 700 00:36:18,680 --> 00:36:21,560 Speaker 1: has to do with the beginning of the unse like 701 00:36:21,600 --> 00:36:23,520 Speaker 1: if this stuff at the beginning of the universe had 702 00:36:23,560 --> 00:36:26,640 Speaker 1: a little bit of a spin, that's the only way 703 00:36:26,680 --> 00:36:29,440 Speaker 1: it could still have spin today, Yeah, because angular momentum 704 00:36:29,600 --> 00:36:33,040 Speaker 1: is conserved. Right, If you are spinning, you will always 705 00:36:33,080 --> 00:36:35,800 Speaker 1: be spinning. There's no way to stop something from spinning 706 00:36:36,000 --> 00:36:38,479 Speaker 1: unless you're coming in from the outside with some other 707 00:36:38,560 --> 00:36:40,840 Speaker 1: spin to cancel it out. If you're talking about the 708 00:36:40,840 --> 00:36:43,600 Speaker 1: whole universe, then there is nothing outside and so if 709 00:36:43,640 --> 00:36:46,760 Speaker 1: the whole universe somehow started out spinning, it should still 710 00:36:46,800 --> 00:36:50,439 Speaker 1: be spinning today, although that spin would get dampened out 711 00:36:50,560 --> 00:36:53,160 Speaker 1: and go to very very small values because of the 712 00:36:53,200 --> 00:36:55,920 Speaker 1: expansion of the universe, like a figure skater shooting her 713 00:36:56,000 --> 00:36:59,000 Speaker 1: arms out for like millions and millions of miles or spin, 714 00:36:59,040 --> 00:37:01,399 Speaker 1: but then go to the to the zero. So that's 715 00:37:01,400 --> 00:37:03,279 Speaker 1: what we're talking about, is is there spin to this 716 00:37:03,320 --> 00:37:06,359 Speaker 1: stuff in the universe and it should persist if it's there, right, 717 00:37:06,520 --> 00:37:08,800 Speaker 1: Because I think what you're saying is that the universe 718 00:37:08,840 --> 00:37:10,920 Speaker 1: had no spin at the Big Bang when it was 719 00:37:10,960 --> 00:37:14,280 Speaker 1: super super tiny small, and thence if it had no spin, 720 00:37:14,880 --> 00:37:18,560 Speaker 1: there's no way for it to gain spin since then 721 00:37:18,880 --> 00:37:22,160 Speaker 1: like it can't like push off against anything right to 722 00:37:22,239 --> 00:37:25,000 Speaker 1: get spin. There's no way to spin the entire universe. 723 00:37:25,040 --> 00:37:27,560 Speaker 1: There's nothing to like push against. Right. If you're talking 724 00:37:27,560 --> 00:37:29,840 Speaker 1: about the whole universe is nothing that you can push against, 725 00:37:29,880 --> 00:37:31,920 Speaker 1: because that would mean something outside the universe and the 726 00:37:31,960 --> 00:37:35,759 Speaker 1: universe is everything, right, unless maybe, like spacetime itself has 727 00:37:35,800 --> 00:37:38,600 Speaker 1: a like a lean, like a lean to it, right, 728 00:37:38,719 --> 00:37:40,600 Speaker 1: or something, you know, like it has a preference for 729 00:37:40,640 --> 00:37:42,839 Speaker 1: a matter and not antimatter. It has a preference for 730 00:37:43,000 --> 00:37:45,040 Speaker 1: certain things, you know, four wards some time and not 731 00:37:45,120 --> 00:37:47,520 Speaker 1: backwards some time. Could it also have like a little 732 00:37:47,520 --> 00:37:49,680 Speaker 1: bit of a spin preference. Yeah, we usually ask this 733 00:37:49,760 --> 00:37:53,759 Speaker 1: question under the assumption that spacetime is homogeneous, meaning it's 734 00:37:53,800 --> 00:37:57,040 Speaker 1: the same everywhere and in every direction. But it's certainly 735 00:37:57,040 --> 00:37:59,480 Speaker 1: possible if we discovered an overall spin to the universe 736 00:37:59,480 --> 00:38:02,320 Speaker 1: to wonder that comes from and you know, could be 737 00:38:02,360 --> 00:38:05,600 Speaker 1: generated by like some features in spacetime that aren't the 738 00:38:05,640 --> 00:38:08,719 Speaker 1: same everywhere I see. But your your basic answer is 739 00:38:08,760 --> 00:38:10,839 Speaker 1: that the stuff in the universe has any spin. Now, 740 00:38:11,080 --> 00:38:13,120 Speaker 1: it must be due to any kind of spin it 741 00:38:13,120 --> 00:38:15,600 Speaker 1: has at the beginning of the universe. But even if 742 00:38:15,600 --> 00:38:16,920 Speaker 1: it had a little bit of a rotation at the 743 00:38:16,920 --> 00:38:19,080 Speaker 1: beginning of the universe, that would have all sort of 744 00:38:19,239 --> 00:38:22,719 Speaker 1: gone to almost zero by now. Yes, So we would 745 00:38:22,760 --> 00:38:25,480 Speaker 1: be very surprised if we look out into the universe, 746 00:38:25,719 --> 00:38:28,800 Speaker 1: measure its overall spin, and find it to be spinning 747 00:38:29,120 --> 00:38:31,480 Speaker 1: at any significant rate. That would be a big shock. 748 00:38:31,640 --> 00:38:34,360 Speaker 1: It would make all your head spin for sure, relative 749 00:38:34,440 --> 00:38:36,360 Speaker 1: to all the chocolate you're eating. It would be a 750 00:38:36,400 --> 00:38:39,800 Speaker 1: fantastic and delicious discovery because it would be a clue 751 00:38:39,920 --> 00:38:43,040 Speaker 1: that's something we think is true, is not that there's 752 00:38:43,080 --> 00:38:45,640 Speaker 1: something else going on that we don't understand, and like 753 00:38:45,800 --> 00:38:49,279 Speaker 1: the biggest, most delicious scales. All right, well, let's get 754 00:38:49,280 --> 00:38:52,480 Speaker 1: into how we could tell if the universe, or at 755 00:38:52,520 --> 00:38:55,040 Speaker 1: least the stuff in the universe, is spinning at any 756 00:38:55,040 --> 00:38:58,279 Speaker 1: significant rate, because I think Daniel is hungry, so let's 757 00:38:58,280 --> 00:39:13,880 Speaker 1: get that answer asap. But first let's stick another quick break. Alright, 758 00:39:13,920 --> 00:39:15,719 Speaker 1: we're talking about whether or not all this stuff in 759 00:39:15,760 --> 00:39:19,200 Speaker 1: the universe is spinning, Dan, and you said it's unlikely 760 00:39:19,239 --> 00:39:22,400 Speaker 1: for it to have any kind of spin, because expanding 761 00:39:22,400 --> 00:39:25,560 Speaker 1: the universe would have killed any sort of momentum. But 762 00:39:25,680 --> 00:39:28,440 Speaker 1: what if I'm thinking, what if the universe was spinning 763 00:39:28,440 --> 00:39:30,600 Speaker 1: a lot at the beginning, couldn't it also have some 764 00:39:30,680 --> 00:39:35,280 Speaker 1: sort of remnant spin twit at this point? Yeah, it would, 765 00:39:35,440 --> 00:39:37,600 Speaker 1: and we might be able to measure that if we 766 00:39:37,800 --> 00:39:41,279 Speaker 1: devise tests that are very very sensitive, and so you're 767 00:39:41,320 --> 00:39:44,760 Speaker 1: right that the current theories of physics suggests that spin 768 00:39:44,880 --> 00:39:48,240 Speaker 1: is dampened by expansion. But we don't have an idea 769 00:39:48,320 --> 00:39:51,759 Speaker 1: for why the universe would or would not be spinning originally. 770 00:39:52,080 --> 00:39:55,840 Speaker 1: So if the universe was somehow born spinning super duper fast, 771 00:39:55,960 --> 00:39:57,719 Speaker 1: we could still measure that today, and that would be 772 00:39:57,719 --> 00:40:01,439 Speaker 1: interesting because our cosmology allows for the universe to spin. 773 00:40:01,520 --> 00:40:04,840 Speaker 1: It's possible for the whole universe to have been born spinning, 774 00:40:04,960 --> 00:40:08,120 Speaker 1: for it to have been a spinning baby shot out 775 00:40:08,120 --> 00:40:12,680 Speaker 1: of the universe womb and doing a triple lets. And 776 00:40:12,760 --> 00:40:14,800 Speaker 1: remember we don't really know much about that birth. We 777 00:40:14,880 --> 00:40:19,319 Speaker 1: talked about possible theories of like infloton fields decaying into 778 00:40:19,400 --> 00:40:22,400 Speaker 1: normal matter. There's are really displaceholders for like where to 779 00:40:22,440 --> 00:40:25,680 Speaker 1: have future ideas the shape of those ideas, but we 780 00:40:25,760 --> 00:40:28,480 Speaker 1: definitely don't have ideas firm enough to where we can say, like, 781 00:40:28,560 --> 00:40:30,880 Speaker 1: the universe should not have been born with any spin. 782 00:40:31,360 --> 00:40:34,239 Speaker 1: For sure, there's a huge opening there for ways the 783 00:40:34,280 --> 00:40:36,560 Speaker 1: universe could have been born and allowing for it to spin, 784 00:40:36,600 --> 00:40:40,440 Speaker 1: And definitely Einstein's ther relativity says it is possible. It's 785 00:40:40,560 --> 00:40:43,920 Speaker 1: meaningful for the stuff in the universe to be spinning, right, 786 00:40:43,960 --> 00:40:45,920 Speaker 1: So I guess that means that if you do discover 787 00:40:46,000 --> 00:40:48,399 Speaker 1: that all the stuff in the universe is spinning right now, 788 00:40:48,760 --> 00:40:50,759 Speaker 1: it maybe shouldn't be that surprising. You'll just tell you 789 00:40:50,800 --> 00:40:52,520 Speaker 1: if it was spinning at the beginning or not. It 790 00:40:52,520 --> 00:40:54,520 Speaker 1: would tell you that it was spinning a lot at 791 00:40:54,520 --> 00:40:56,400 Speaker 1: the beginning, and then you'd have to go into your 792 00:40:56,440 --> 00:40:58,480 Speaker 1: theories and say, like, well, how do I make that happen? 793 00:40:59,000 --> 00:41:01,120 Speaker 1: You know? Is it a diverse where the spin is 794 00:41:01,160 --> 00:41:03,279 Speaker 1: somehow random and we just got a big serving of 795 00:41:03,320 --> 00:41:07,360 Speaker 1: it is necessary because of some property of the universe beforehand, 796 00:41:07,400 --> 00:41:10,120 Speaker 1: the universe is inherently always spinning. It would be a 797 00:41:10,120 --> 00:41:13,160 Speaker 1: lot of really fun questions. Yeah, or maybe the universe 798 00:41:13,200 --> 00:41:16,920 Speaker 1: mom just hit a lot of chocolate before the baby 799 00:41:17,000 --> 00:41:22,120 Speaker 1: universe was born and made the baby universe spin out 800 00:41:22,120 --> 00:41:24,200 Speaker 1: of control. All right, So then what are some of 801 00:41:24,200 --> 00:41:26,959 Speaker 1: the ways that we could maybe test today, like where 802 00:41:27,000 --> 00:41:30,000 Speaker 1: we are now in this spinning or not spinning universe, 803 00:41:30,000 --> 00:41:32,680 Speaker 1: whether or not things are spinning everything, whether or not 804 00:41:32,760 --> 00:41:35,080 Speaker 1: everything is spinning. So people have been thinking about this 805 00:41:35,160 --> 00:41:37,880 Speaker 1: for decades, and remember Einstein's theory of relativity is only 806 00:41:37,920 --> 00:41:40,719 Speaker 1: about a hundred years old. To this concept that the 807 00:41:40,800 --> 00:41:44,719 Speaker 1: universe can spin absolutely relative to space time. He's only 808 00:41:44,719 --> 00:41:47,160 Speaker 1: about a hundred years old, and it took a while 809 00:41:47,200 --> 00:41:49,719 Speaker 1: for people to understand what it means. You know, Einstein 810 00:41:49,760 --> 00:41:52,359 Speaker 1: actually believed Mark for decades until later in his life 811 00:41:52,360 --> 00:41:55,080 Speaker 1: when he was like, no, beautiful, but I think he's wrong. 812 00:41:55,600 --> 00:41:57,920 Speaker 1: And it's really only like fifty or so years that 813 00:41:57,920 --> 00:41:59,680 Speaker 1: people have been are thinking about this in a way 814 00:41:59,680 --> 00:42:01,960 Speaker 1: that they test it. And one of the simplest ideas 815 00:42:02,080 --> 00:42:04,399 Speaker 1: is just like, well, let's just look and see if 816 00:42:04,400 --> 00:42:08,880 Speaker 1: the universe appears to be spinning relative to some fixed point. 817 00:42:09,200 --> 00:42:11,080 Speaker 1: You mean looking at all the stuff in the universe, 818 00:42:11,120 --> 00:42:13,640 Speaker 1: not the universe itself. Yeah, all the stuff in the universe. 819 00:42:13,680 --> 00:42:16,839 Speaker 1: And so, for example, are the galaxies, the distant galaxies? 820 00:42:16,880 --> 00:42:20,880 Speaker 1: Are they spinning relative to the Milky Way or relative 821 00:42:20,920 --> 00:42:22,759 Speaker 1: to the Solar System? And the cool thing is that 822 00:42:22,800 --> 00:42:25,800 Speaker 1: you can treat the Solar System, because itself is spinning, 823 00:42:25,840 --> 00:42:28,560 Speaker 1: as a sort of gyroscope. That the Solar System is spinning, 824 00:42:28,600 --> 00:42:30,600 Speaker 1: and it's going to continue to spin, and because of 825 00:42:30,640 --> 00:42:33,680 Speaker 1: conservation of Anglo momentum, it has to keep spinning and 826 00:42:33,719 --> 00:42:37,400 Speaker 1: basically the same direction, so it like defines an access 827 00:42:37,760 --> 00:42:39,880 Speaker 1: and then you can ask, well, is the rest of 828 00:42:39,920 --> 00:42:43,759 Speaker 1: the universe sort of spinning around us relative to the 829 00:42:43,800 --> 00:42:45,520 Speaker 1: Milky Way? What do you mean? I would that tell 830 00:42:45,560 --> 00:42:47,440 Speaker 1: you if the universe was spinning, I mean the stuff 831 00:42:47,440 --> 00:42:49,400 Speaker 1: in the universe was spinning. Well, it would tell you 832 00:42:49,440 --> 00:42:52,200 Speaker 1: whether the universe was spinning relative to the Milky Way. 833 00:42:52,239 --> 00:42:55,120 Speaker 1: At least we can measure the Milky Way spin, right, 834 00:42:55,320 --> 00:42:57,960 Speaker 1: because we can tell whether an individual object needs spinning, 835 00:42:58,360 --> 00:43:00,360 Speaker 1: and so that gives us like a reference point, and 836 00:43:00,360 --> 00:43:02,200 Speaker 1: then we can ask whether the rest of the universe 837 00:43:02,239 --> 00:43:04,600 Speaker 1: is spinning relative to us. So we can measure our 838 00:43:04,680 --> 00:43:07,400 Speaker 1: spin relative to spacetime, and then we can measure the 839 00:43:07,440 --> 00:43:10,080 Speaker 1: rest of the universe is spin relative to the Milky Way, 840 00:43:10,160 --> 00:43:12,680 Speaker 1: just by looking at the galaxies and saying, like, are 841 00:43:12,719 --> 00:43:16,160 Speaker 1: they moving relative to us? Oh? I see, But isn't 842 00:43:16,160 --> 00:43:18,320 Speaker 1: that sort of a given, Like don't we expect the 843 00:43:18,360 --> 00:43:21,520 Speaker 1: Milky Way to be, you know, spinning in some weird 844 00:43:21,560 --> 00:43:24,960 Speaker 1: direction relative to everything else, all the stuff in the universe. 845 00:43:25,120 --> 00:43:27,600 Speaker 1: We can measure the Milky Way spin relative to spacetime 846 00:43:27,640 --> 00:43:30,760 Speaker 1: because it's absolute, and then we can measure the motion 847 00:43:30,800 --> 00:43:33,360 Speaker 1: of the distance galaxies relative to the Milky Way, and 848 00:43:33,400 --> 00:43:36,040 Speaker 1: if that's exactly the opposite, then that suggests that the 849 00:43:36,080 --> 00:43:39,440 Speaker 1: whole rest of the universe is essentially not spinning. Oh, 850 00:43:39,480 --> 00:43:42,560 Speaker 1: I see, Because you're saying that you can measure the 851 00:43:42,600 --> 00:43:45,400 Speaker 1: spinning of stuff relatives to spacetime. There is sort of 852 00:43:45,400 --> 00:43:48,000 Speaker 1: like a reference frame in the universe, and that's called 853 00:43:48,040 --> 00:43:50,719 Speaker 1: space time. And you're saying, because the Milky Way is 854 00:43:50,719 --> 00:43:53,760 Speaker 1: close to us, we can measure that pretty accurately. It 855 00:43:53,760 --> 00:43:55,840 Speaker 1: gives us sort of a compass of how we're spinning 856 00:43:55,840 --> 00:43:58,440 Speaker 1: relative to spacetime. And then you're saying, let's look at 857 00:43:58,480 --> 00:44:03,680 Speaker 1: everything else and see if it's rotating relative to that exactly. So, 858 00:44:03,960 --> 00:44:06,440 Speaker 1: say you're spinning around inside of a room, you can 859 00:44:06,480 --> 00:44:08,480 Speaker 1: have a way to measure your own spin. You have 860 00:44:08,480 --> 00:44:11,040 Speaker 1: like a gyroscope that tells you your own spin, and 861 00:44:11,040 --> 00:44:13,200 Speaker 1: you can also measure your spin relative to the walls. 862 00:44:13,200 --> 00:44:15,680 Speaker 1: So those two numbers agree, that tells you the walls 863 00:44:15,719 --> 00:44:18,600 Speaker 1: are not spinning. Those two numbers disagree. That tells you, Oh, well, 864 00:44:18,640 --> 00:44:20,680 Speaker 1: I guess the walls are also spinning. So that's what 865 00:44:20,719 --> 00:44:22,279 Speaker 1: we can do. We can measure our spin of the 866 00:44:22,320 --> 00:44:24,000 Speaker 1: Milky Way and then we can measure the spin of 867 00:44:24,000 --> 00:44:26,680 Speaker 1: the Milky Way relative to the distant galaxies, and then 868 00:44:26,680 --> 00:44:30,680 Speaker 1: we can ask are the distant galaxies spinning in absolute sense? 869 00:44:31,280 --> 00:44:33,120 Speaker 1: But I guess my question is why do even need 870 00:44:33,160 --> 00:44:34,759 Speaker 1: to go that far? Like, couldn't I just use the 871 00:44:34,800 --> 00:44:38,200 Speaker 1: gyroscope here on Earth and then measure the galaxies relative 872 00:44:38,239 --> 00:44:40,319 Speaker 1: to my little gyroscope. Yeah, but the Milky Way is 873 00:44:40,320 --> 00:44:43,239 Speaker 1: a better gyroscope than your little gyroscope. The Milky Way 874 00:44:43,239 --> 00:44:46,279 Speaker 1: and the Solar System provide pretty nice gyroscope because it's 875 00:44:46,320 --> 00:44:48,759 Speaker 1: a huge amount of mass and a very long lever arm, 876 00:44:49,280 --> 00:44:51,440 Speaker 1: and so they're very precise. But there are lots of 877 00:44:51,440 --> 00:44:54,280 Speaker 1: ways you can construct this experiment. The real limitation, though, 878 00:44:54,680 --> 00:44:57,360 Speaker 1: is that it's very hard to observe the motion of 879 00:44:57,400 --> 00:45:01,520 Speaker 1: those distant galaxies because they're really really far away, and 880 00:45:01,560 --> 00:45:04,040 Speaker 1: so they hardly move at all. And we've only been 881 00:45:04,040 --> 00:45:06,040 Speaker 1: looking at them for like a hundred years. It's only 882 00:45:06,200 --> 00:45:08,680 Speaker 1: Hubble a hundred years ago they even discover that there 883 00:45:08,680 --> 00:45:11,400 Speaker 1: were other galaxies out there. So if they are moving, 884 00:45:11,440 --> 00:45:14,040 Speaker 1: they're moving very very slow, not in a way that 885 00:45:14,080 --> 00:45:20,000 Speaker 1: we can tell relative to spacetime, right, They're moving super slow. 886 00:45:20,200 --> 00:45:22,520 Speaker 1: They're moving they're expanding, right, they're moving away from us. 887 00:45:22,520 --> 00:45:25,520 Speaker 1: But now we're talking about not radial motion away from us, 888 00:45:25,719 --> 00:45:29,600 Speaker 1: the rotational motion right perpendicular to the line between us 889 00:45:29,640 --> 00:45:32,280 Speaker 1: and them, and we haven't seen that kind of rotation. 890 00:45:32,560 --> 00:45:34,279 Speaker 1: Like I think you're saying, like, if you correct for 891 00:45:34,320 --> 00:45:36,319 Speaker 1: the motion of the Earth and correct for the motion 892 00:45:36,360 --> 00:45:38,200 Speaker 1: of the Earth around the Solar System and the milk 893 00:45:38,200 --> 00:45:40,560 Speaker 1: away and all that, it would be hard to tell 894 00:45:40,600 --> 00:45:43,040 Speaker 1: because they're so far away, Like for us to see 895 00:45:43,040 --> 00:45:46,719 Speaker 1: them spinning around and around the cosmos, it would have 896 00:45:46,760 --> 00:45:49,920 Speaker 1: to be moving like ridiculously fast, right, Because we can 897 00:45:49,960 --> 00:45:53,359 Speaker 1: measure their velocity in a radial direction pretty well because 898 00:45:53,360 --> 00:45:56,480 Speaker 1: of Doppler effect. Measuring their velocity in the other direction, 899 00:45:56,560 --> 00:46:00,600 Speaker 1: you know, requires seeing their change in their own relative 900 00:46:00,640 --> 00:46:02,840 Speaker 1: to the Milky Way, which requires like you know, seeing 901 00:46:02,880 --> 00:46:05,440 Speaker 1: them actually move, and that's really hard to do for 902 00:46:05,480 --> 00:46:07,920 Speaker 1: stars and even harder to do for galaxies. They need 903 00:46:07,960 --> 00:46:09,799 Speaker 1: to be either moving really really fast, or you have 904 00:46:09,840 --> 00:46:11,880 Speaker 1: to observe for like a billion years and we're only 905 00:46:11,920 --> 00:46:14,319 Speaker 1: a hundred years in. Yeah, that's the real limitation. Like 906 00:46:14,360 --> 00:46:16,000 Speaker 1: it's possible, and you just need a lot of time, 907 00:46:16,239 --> 00:46:17,880 Speaker 1: or they need to be moving really really fast in 908 00:46:17,880 --> 00:46:20,200 Speaker 1: an obvious way that we can see it, and that's 909 00:46:20,200 --> 00:46:24,040 Speaker 1: not happening. Can you just to ask him? Call him 910 00:46:24,080 --> 00:46:26,880 Speaker 1: all right? So that that one has its limitations. You're 911 00:46:26,920 --> 00:46:29,560 Speaker 1: not gonna gonna get a Nobel prize anytime soon with 912 00:46:29,600 --> 00:46:31,760 Speaker 1: that method. What are some other ways we can measure? 913 00:46:31,920 --> 00:46:33,799 Speaker 1: Other things we can do is to look at the 914 00:46:33,840 --> 00:46:37,279 Speaker 1: expansion of the universe. So we know that things that 915 00:46:37,320 --> 00:46:39,440 Speaker 1: are far away from us are moving away from us, 916 00:46:39,480 --> 00:46:42,440 Speaker 1: and we know that that expansion is accelerating. So this 917 00:46:42,520 --> 00:46:45,359 Speaker 1: is the discovery of dark energy. That something is stretching out. 918 00:46:45,400 --> 00:46:48,880 Speaker 1: The universe seems to be creating new space between points 919 00:46:48,920 --> 00:46:51,279 Speaker 1: all of the time. And the interesting thing is that 920 00:46:51,320 --> 00:46:54,719 Speaker 1: cosmologists say that if the whole universe was rotating, if 921 00:46:54,719 --> 00:46:57,200 Speaker 1: everything was spinning, then that would look a little different. 922 00:46:57,200 --> 00:46:59,800 Speaker 1: That expansion would look different than it would if the 923 00:47:00,040 --> 00:47:03,080 Speaker 1: universe was not spinning. And so the way that we 924 00:47:03,120 --> 00:47:05,920 Speaker 1: measure that the universe is expanding is a couple of ways. 925 00:47:06,280 --> 00:47:08,560 Speaker 1: One is that we look at type one A supernova, 926 00:47:08,640 --> 00:47:11,520 Speaker 1: these standard candles that we know exactly how bright they 927 00:47:11,520 --> 00:47:13,719 Speaker 1: should be, and so when we see one, we can 928 00:47:13,719 --> 00:47:16,319 Speaker 1: tell how far away it is because of how bright 929 00:47:16,360 --> 00:47:18,680 Speaker 1: we see it. We have these like tracer points in 930 00:47:18,719 --> 00:47:21,760 Speaker 1: the universe, so we can see their expansion over time, 931 00:47:21,760 --> 00:47:23,560 Speaker 1: and we can see the history of the expansion of 932 00:47:23,600 --> 00:47:27,080 Speaker 1: the universe. And if there was a swirl in that expansion, 933 00:47:27,080 --> 00:47:30,480 Speaker 1: if the universe was rotating at the same time as expanding, 934 00:47:30,800 --> 00:47:32,640 Speaker 1: then that would look a little different than if it 935 00:47:32,719 --> 00:47:35,640 Speaker 1: was just expanding in a purely radial way. What do 936 00:47:35,640 --> 00:47:37,680 Speaker 1: you mean, because I would mess with the I guess 937 00:47:37,719 --> 00:47:41,239 Speaker 1: the basic motion of things, right, because it suddenly has 938 00:47:41,400 --> 00:47:44,680 Speaker 1: an extra component of velocity and it's feeling an extra 939 00:47:44,719 --> 00:47:47,879 Speaker 1: component of exploration. Yeah. Imagine you're like on a Merry 940 00:47:47,920 --> 00:47:49,920 Speaker 1: Go Round and you have a bunch of friends and 941 00:47:49,960 --> 00:47:53,040 Speaker 1: you all throw ping pong balls out. If you're spinning, 942 00:47:53,160 --> 00:47:55,440 Speaker 1: or if you're not spinning, then those ping pong balls 943 00:47:55,480 --> 00:47:58,760 Speaker 1: have a different path, right, They would curve if you're spinning. 944 00:47:58,840 --> 00:48:01,560 Speaker 1: That's one way to measure or rotation. And so we're 945 00:48:01,560 --> 00:48:03,640 Speaker 1: trying to measure the rotation of all the stuff in 946 00:48:03,640 --> 00:48:06,160 Speaker 1: the universe by looking at the path of these tracers, 947 00:48:06,200 --> 00:48:08,880 Speaker 1: these type one a supernova to see is it consistent 948 00:48:08,880 --> 00:48:11,800 Speaker 1: which is flying straight out or is it consistent with curving. 949 00:48:12,239 --> 00:48:14,640 Speaker 1: We can't observe them for very long. But we have 950 00:48:14,840 --> 00:48:17,520 Speaker 1: these momentary tracers, then you can do some sort of 951 00:48:17,520 --> 00:48:20,279 Speaker 1: like back calculation to say, like are they consistent with 952 00:48:20,440 --> 00:48:23,600 Speaker 1: rotation or are they consistent with pure expansion? Oh? I see. 953 00:48:23,640 --> 00:48:25,479 Speaker 1: I think what you're saying is like, like if everything 954 00:48:25,520 --> 00:48:27,920 Speaker 1: in the universe was in a Merry Go round, we 955 00:48:27,960 --> 00:48:30,920 Speaker 1: would see the stars, the supernova or at least the 956 00:48:30,960 --> 00:48:33,680 Speaker 1: stuff around like the equator. That stuff would be maybe 957 00:48:33,680 --> 00:48:37,600 Speaker 1: expanding faster, maybe or moving differently than the stuff like 958 00:48:37,680 --> 00:48:40,239 Speaker 1: above and below us on the Merry Go round. Yeah, 959 00:48:40,239 --> 00:48:42,880 Speaker 1: if there's an overall rotation, that implies that there's a 960 00:48:42,960 --> 00:48:46,200 Speaker 1: rotation in some plane, right, some access around which you 961 00:48:46,239 --> 00:48:49,400 Speaker 1: are rotating, and that essentially defines a north and a 962 00:48:49,520 --> 00:48:52,280 Speaker 1: south just the same way like the Earth's rotation defines 963 00:48:52,320 --> 00:48:54,440 Speaker 1: a north pole and a south pole, and the Solar 964 00:48:54,480 --> 00:48:57,120 Speaker 1: system has a north and the south defined by its rotation. 965 00:48:57,520 --> 00:49:00,200 Speaker 1: So that would create different directions in the sky where 966 00:49:00,200 --> 00:49:04,319 Speaker 1: things look different, basically a huge anisotropy. We actually talked 967 00:49:04,320 --> 00:49:06,840 Speaker 1: about on the podcast once about this access of evil, 968 00:49:06,880 --> 00:49:09,399 Speaker 1: this idea that maybe things in the universe do look 969 00:49:09,440 --> 00:49:12,359 Speaker 1: a little bit different north to south if depending on 970 00:49:12,360 --> 00:49:14,560 Speaker 1: how you define it. That's exactly the kind of thing 971 00:49:14,560 --> 00:49:16,920 Speaker 1: you would expect to see if the universe was rotating. 972 00:49:16,920 --> 00:49:19,319 Speaker 1: You'd expect to see some difference in one half of 973 00:49:19,320 --> 00:49:21,319 Speaker 1: the sky versus the other half of the sky. Right, 974 00:49:21,320 --> 00:49:23,080 Speaker 1: you would expect it to be a little wider in 975 00:49:23,120 --> 00:49:27,720 Speaker 1: the middle around the waistline. The universe is either rotating 976 00:49:27,800 --> 00:49:29,680 Speaker 1: or been eating too much chocolate, you know, one of 977 00:49:29,680 --> 00:49:32,200 Speaker 1: those two. There's only two posibilities. You can use similar 978 00:49:32,280 --> 00:49:35,840 Speaker 1: tests with another very sensitive probe of the universe's expansion. 979 00:49:36,080 --> 00:49:39,560 Speaker 1: That's the cosmic microwave background radiation. That's this light from 980 00:49:39,560 --> 00:49:42,479 Speaker 1: the very very early universe. And we were talking about 981 00:49:42,520 --> 00:49:45,560 Speaker 1: how if this rotation exists, it should have existed a 982 00:49:45,560 --> 00:49:47,960 Speaker 1: long time ago. It's actually much more powerful to see 983 00:49:47,960 --> 00:49:51,000 Speaker 1: it earlier on, before the universe expanded so much, because 984 00:49:51,000 --> 00:49:53,440 Speaker 1: the rotation would be more dramatic and so in the 985 00:49:53,480 --> 00:49:55,960 Speaker 1: same way that if the universe is rotating, it would 986 00:49:56,000 --> 00:49:58,600 Speaker 1: affect the way things are expanding, it would also affect 987 00:49:58,600 --> 00:50:02,240 Speaker 1: that plasma that generates did that CNB light The plasma 988 00:50:02,280 --> 00:50:04,759 Speaker 1: is very sensitive to like how much dark matter there 989 00:50:04,920 --> 00:50:07,680 Speaker 1: is and how it's moving, and how the normal matter 990 00:50:07,760 --> 00:50:10,560 Speaker 1: is sloshing around into and out of those dark matter 991 00:50:10,600 --> 00:50:13,840 Speaker 1: gravitational wells, and if there was an overall spin, it 992 00:50:13,880 --> 00:50:16,400 Speaker 1: would affect those patterns in very subtle ways, and people 993 00:50:16,400 --> 00:50:20,720 Speaker 1: have studied those and not seeing any evidence for universal rotation. 994 00:50:21,000 --> 00:50:23,279 Speaker 1: M M. It's kind of like you we talked about 995 00:50:23,320 --> 00:50:25,879 Speaker 1: it before, how the cosmic microwave background is like a 996 00:50:25,920 --> 00:50:29,080 Speaker 1: picture of the baby universe, like an early picture of 997 00:50:29,080 --> 00:50:32,200 Speaker 1: the universe, and so you you don't see any Basically, 998 00:50:32,200 --> 00:50:34,279 Speaker 1: what you're saying is you don't see any spin in 999 00:50:34,320 --> 00:50:38,440 Speaker 1: that picture, nor do you see it being uh, like 1000 00:50:38,480 --> 00:50:40,799 Speaker 1: the baby's not extra wide around the middle. Yeah, And 1001 00:50:40,800 --> 00:50:43,440 Speaker 1: it's a little subtle because it's not like you're looking 1002 00:50:43,480 --> 00:50:46,200 Speaker 1: at the actual universe and seeing it's spin. You're looking 1003 00:50:46,239 --> 00:50:49,600 Speaker 1: at like the patterns that spin would cause in the 1004 00:50:49,640 --> 00:50:53,360 Speaker 1: clumpiness of the universe. It would make very distinctive patterns. 1005 00:50:53,400 --> 00:50:55,879 Speaker 1: And this is actually the most sensitive test we have 1006 00:50:56,280 --> 00:50:59,719 Speaker 1: for the universe's rotation, is this cosmic microwave background light. 1007 00:51:00,200 --> 00:51:02,600 Speaker 1: In their early eighties, people saw some weird stuff in 1008 00:51:02,600 --> 00:51:05,160 Speaker 1: the sky from radio signals that led them to believe 1009 00:51:05,360 --> 00:51:08,759 Speaker 1: maybe the universe was rotating. There's a paper in two 1010 00:51:08,800 --> 00:51:11,480 Speaker 1: I read from a guy in Manchester in Birch who 1011 00:51:11,480 --> 00:51:13,840 Speaker 1: claimed to be measuring the rotation of the universe that 1012 00:51:14,000 --> 00:51:18,040 Speaker 1: attended the minus thirteen radiants per year. But this measurement 1013 00:51:18,080 --> 00:51:21,040 Speaker 1: in the CNB is more powerful and is not consistent 1014 00:51:21,080 --> 00:51:24,759 Speaker 1: with any rotation, So people think Burchess measurement was probably wrong. Well, 1015 00:51:24,800 --> 00:51:26,719 Speaker 1: I'm getting this sort of the picture that if you're 1016 00:51:26,760 --> 00:51:30,200 Speaker 1: asking the question, is the stuff in the universe spinning? 1017 00:51:30,760 --> 00:51:33,040 Speaker 1: If it was spinning, then you would see some sort 1018 00:51:33,080 --> 00:51:36,600 Speaker 1: of like you said, an isotriptropy, meaning like it would 1019 00:51:36,640 --> 00:51:39,239 Speaker 1: the universe would look differently whether you're looking at the 1020 00:51:39,440 --> 00:51:42,400 Speaker 1: spinning direction or whether you're looking at the its waistline 1021 00:51:42,440 --> 00:51:45,200 Speaker 1: or the equator of the spinning stuff in the universe. 1022 00:51:45,320 --> 00:51:48,239 Speaker 1: And it seems like for for all accounts looking at 1023 00:51:48,280 --> 00:51:50,960 Speaker 1: galaxies and looking at the baby picture of the universe, 1024 00:51:51,360 --> 00:51:54,279 Speaker 1: there is no different or like preferred direction that you 1025 00:51:54,320 --> 00:51:56,520 Speaker 1: can see as far as we can tell. Here's a 1026 00:51:56,520 --> 00:51:58,640 Speaker 1: study we talked about on the Access of Evil episode 1027 00:51:58,640 --> 00:52:00,600 Speaker 1: where people looked at the spin of Alexis and they 1028 00:52:00,600 --> 00:52:03,200 Speaker 1: found that galaxies in one direction of sky tend to 1029 00:52:03,239 --> 00:52:06,400 Speaker 1: be spinning left more than any other direction of the sky. 1030 00:52:06,480 --> 00:52:08,720 Speaker 1: And they claim this is maybe evidence for the universe 1031 00:52:08,760 --> 00:52:11,120 Speaker 1: to be rotating. But a lot of people criticize that 1032 00:52:11,120 --> 00:52:14,480 Speaker 1: paper and think that it probably underestimates systematic effects that 1033 00:52:14,520 --> 00:52:17,719 Speaker 1: could cause that, you know, local gravitational effects or or 1034 00:52:17,760 --> 00:52:20,440 Speaker 1: other uncertainties that they didn't take into account. So overall, 1035 00:52:20,760 --> 00:52:25,520 Speaker 1: there's no evidence for universal rotation, although our cosmology allows it. Right, 1036 00:52:25,520 --> 00:52:28,480 Speaker 1: it is possible our universe to rotate, it just doesn't 1037 00:52:28,520 --> 00:52:31,319 Speaker 1: seem to be doing that right, or at least not 1038 00:52:31,520 --> 00:52:34,920 Speaker 1: to tend to the negative nine radiance per year, which 1039 00:52:35,120 --> 00:52:37,520 Speaker 1: sounds like a small number. It's like point zero zero 1040 00:52:37,600 --> 00:52:41,200 Speaker 1: zero zero nine zeros and then a one. But if you, 1041 00:52:41,320 --> 00:52:43,840 Speaker 1: like you said before, like you know, the universe expanded 1042 00:52:43,880 --> 00:52:48,200 Speaker 1: tend to the what like thirties sixty two times since 1043 00:52:48,239 --> 00:52:51,040 Speaker 1: the Big Bang, And so it could just be that 1044 00:52:51,120 --> 00:52:54,600 Speaker 1: are these instruments this way of knowing, it's not accurate 1045 00:52:54,719 --> 00:52:56,320 Speaker 1: enough yet, Like there could be a little bit of 1046 00:52:56,360 --> 00:52:59,160 Speaker 1: spin down there still underneath the what we can measure. 1047 00:52:59,280 --> 00:53:02,320 Speaker 1: You will never have infinite precision, and so either the 1048 00:53:02,400 --> 00:53:05,879 Speaker 1: universe is not spinning or spinning very very gently. Yeah, 1049 00:53:05,920 --> 00:53:09,319 Speaker 1: it's a kitty merry go around. You know, nobody wants 1050 00:53:09,360 --> 00:53:13,640 Speaker 1: us to throw up all that chocolate. Yeah, nobody wants 1051 00:53:13,719 --> 00:53:17,320 Speaker 1: the six flags crazy roller coaster eversion of the universe. 1052 00:53:17,800 --> 00:53:20,279 Speaker 1: So I guess the answer is, is the stuff in 1053 00:53:20,320 --> 00:53:22,799 Speaker 1: the universe spinning? Not that we can tell, but it 1054 00:53:22,840 --> 00:53:26,000 Speaker 1: could still be spinning a little bit. We just don't 1055 00:53:26,000 --> 00:53:29,359 Speaker 1: know for sure yet. And fascinatingly, we could tell if 1056 00:53:29,400 --> 00:53:33,640 Speaker 1: the stuff in the universe was spinning. Spin itself is absolute, 1057 00:53:33,680 --> 00:53:36,360 Speaker 1: and that tells you something really deep about the nature 1058 00:53:36,400 --> 00:53:40,080 Speaker 1: of space and time and motion. That velocity is relative, 1059 00:53:40,120 --> 00:53:44,680 Speaker 1: but acceleration is not. Acceleration is absolute relative to space 1060 00:53:44,800 --> 00:53:47,239 Speaker 1: time itself. Yeah, and it would also sort of tell 1061 00:53:47,280 --> 00:53:49,960 Speaker 1: you that the universe kind of has a direction, right, 1062 00:53:50,000 --> 00:53:52,160 Speaker 1: It kind of would have a north and a south, 1063 00:53:52,360 --> 00:53:56,240 Speaker 1: and a tropical zone. It prefers dark chocolate to white chocolate. 1064 00:53:56,400 --> 00:53:59,000 Speaker 1: All right, Well, um, we hope your head is not 1065 00:53:59,120 --> 00:54:02,239 Speaker 1: spinning from all that discussion about spinning. Well, we hope 1066 00:54:02,239 --> 00:54:04,239 Speaker 1: that it does sort of make you think about whether 1067 00:54:04,360 --> 00:54:06,279 Speaker 1: or not the things around you are moving the way 1068 00:54:06,320 --> 00:54:08,960 Speaker 1: you think they are, and whether or not the universe 1069 00:54:09,080 --> 00:54:12,720 Speaker 1: was maybe born a pretty chill baby or a crazy 1070 00:54:12,719 --> 00:54:14,840 Speaker 1: spinning baby. And I hope you come away a little 1071 00:54:14,880 --> 00:54:17,240 Speaker 1: bit in awe of the fact that we can ask 1072 00:54:17,400 --> 00:54:21,400 Speaker 1: such amazing enormous questions about the nature of the cosmos, 1073 00:54:21,680 --> 00:54:24,160 Speaker 1: and that we have ways just from this tiny spinning 1074 00:54:24,280 --> 00:54:28,000 Speaker 1: rock finding initial answers to these questions. Yeah, and that 1075 00:54:28,040 --> 00:54:31,319 Speaker 1: we can talk about it in an hour and only 1076 00:54:31,360 --> 00:54:35,560 Speaker 1: make forty seven chocolate references. That's right, only make the 1077 00:54:35,719 --> 00:54:39,239 Speaker 1: forty seven bad chocolate plants. All right, Well, we hope 1078 00:54:39,280 --> 00:54:42,480 Speaker 1: you enjoyed that. Thanks for joining us, see you next time. 1079 00:54:50,280 --> 00:54:53,080 Speaker 1: Thanks for listening, and remember that Daniel and Jorge Explain 1080 00:54:53,160 --> 00:54:56,000 Speaker 1: the Universe is a production of I heart Radio. For 1081 00:54:56,200 --> 00:54:59,120 Speaker 1: more podcast from my heart Radio, visit the i heart 1082 00:54:59,200 --> 00:55:02,759 Speaker 1: Radio app, Apple Podcasts, or wherever you listen to your 1083 00:55:02,840 --> 00:55:04,560 Speaker 1: favorite shows. H