1 00:00:08,480 --> 00:00:13,640 Speaker 1: Hey, Daniel, you're often saying that things in space are beautiful. Yeah, 2 00:00:13,680 --> 00:00:16,000 Speaker 1: you know, I never look at a telescope image and 3 00:00:16,040 --> 00:00:19,760 Speaker 1: think yuck. I love the swirls of galaxies, I love 4 00:00:19,800 --> 00:00:23,040 Speaker 1: the explosions of stars. It's all gorgeous. But what makes 5 00:00:23,079 --> 00:00:26,080 Speaker 1: it beautiful? Is it the symmetry? No, I think it's 6 00:00:26,079 --> 00:00:28,800 Speaker 1: beautiful just to see the power of physics and action 7 00:00:28,880 --> 00:00:31,760 Speaker 1: at a grand scale. So would you still think something 8 00:00:31,800 --> 00:00:34,480 Speaker 1: in space was beautiful if it was a little off? 9 00:00:34,680 --> 00:00:36,880 Speaker 1: Why did you do something? Or hey, is there something 10 00:00:36,880 --> 00:00:38,519 Speaker 1: I should know about? I mean, I'm not saying I 11 00:00:38,560 --> 00:00:40,680 Speaker 1: had anything to do with it, but you know, maybe 12 00:00:40,760 --> 00:00:46,080 Speaker 1: just be open minded about the shape of things in space. Fortunately, 13 00:00:46,200 --> 00:00:49,479 Speaker 1: I love galaxies and stars of all shapes and sizes. 14 00:01:05,360 --> 00:01:09,200 Speaker 1: I am more handmade cartoonist and the creator of PhD comics. 15 00:01:09,360 --> 00:01:13,160 Speaker 1: I'm Daniel. I'm a particle physicist, and I do really 16 00:01:13,200 --> 00:01:16,240 Speaker 1: think the universe is beautiful. There's a lot to appreciate 17 00:01:16,319 --> 00:01:19,480 Speaker 1: out there, right. It's big and amazing and quite sparkly 18 00:01:19,720 --> 00:01:22,120 Speaker 1: spaces it is, and it makes me wonder, why do 19 00:01:22,200 --> 00:01:24,840 Speaker 1: we find our universe beautiful? Are we lucky that we 20 00:01:24,920 --> 00:01:27,320 Speaker 1: just ended up in the universe that we find beautiful 21 00:01:27,680 --> 00:01:30,679 Speaker 1: or is it sort of predetermined that any universe we 22 00:01:30,680 --> 00:01:33,840 Speaker 1: would find ourselves in we would appreciate Somehow do you 23 00:01:33,840 --> 00:01:37,480 Speaker 1: think it's there's an evolutionary advantage to finding the universe beautiful? 24 00:01:37,600 --> 00:01:39,960 Speaker 1: Like you know, maybe there were some early humans who 25 00:01:40,000 --> 00:01:43,240 Speaker 1: hated the universe, but you know they didn't make it 26 00:01:44,080 --> 00:01:48,200 Speaker 1: because they got depressed about living in something they didn't like. Yeah, 27 00:01:48,240 --> 00:01:50,920 Speaker 1: I would like to think that there's an evolutionary advantage 28 00:01:50,960 --> 00:01:53,560 Speaker 1: to joy, but I'm not a biologist, so it's too 29 00:01:53,560 --> 00:01:56,720 Speaker 1: far out of my Bailey way. But welcome to our podcast. 30 00:01:56,800 --> 00:01:59,960 Speaker 1: Daniel and Jorge explained the universe in production of I Heartare, 31 00:02:00,320 --> 00:02:02,880 Speaker 1: in which we marvel at the beauty of the universe 32 00:02:02,920 --> 00:02:05,919 Speaker 1: and try to unravel its intermting. We look at everything 33 00:02:05,960 --> 00:02:08,320 Speaker 1: around us and ask why is it that way? Why 34 00:02:08,560 --> 00:02:10,920 Speaker 1: isn't it this other way? What does it mean that 35 00:02:11,040 --> 00:02:13,720 Speaker 1: it swirls this way and bends that way and twist 36 00:02:13,840 --> 00:02:16,720 Speaker 1: this other direction. We look everywhere in the universe and 37 00:02:16,760 --> 00:02:19,560 Speaker 1: we never stop asking why because there is a lot 38 00:02:19,639 --> 00:02:23,880 Speaker 1: out there for us to observe and explore and appreciate. 39 00:02:24,240 --> 00:02:26,320 Speaker 1: And that's a very interesting word, isn't it. Daniel and 40 00:02:26,480 --> 00:02:30,920 Speaker 1: to appreciate the universe and space and everything in it absolutely. 41 00:02:30,960 --> 00:02:32,840 Speaker 1: And one thing I love when we look at like 42 00:02:32,919 --> 00:02:36,640 Speaker 1: Hubble images is seeing the dynamics. I mean, you imagine 43 00:02:36,639 --> 00:02:39,200 Speaker 1: that things out there in space are fixed, their static. 44 00:02:39,240 --> 00:02:41,120 Speaker 1: You're just sort of looking at a picture. But when 45 00:02:41,160 --> 00:02:44,080 Speaker 1: you see these images from Hubble, you see flows. You 46 00:02:44,120 --> 00:02:48,520 Speaker 1: see like explosions, you see gas clouds smashing into each other. 47 00:02:48,720 --> 00:02:51,200 Speaker 1: Of course, it's on the millions of years time scale, 48 00:02:51,240 --> 00:02:53,160 Speaker 1: so you're seeing one image of it. But even just 49 00:02:53,240 --> 00:02:56,760 Speaker 1: from that one image, you can tell there's stuff going on. 50 00:02:56,880 --> 00:02:59,560 Speaker 1: So you're thinking faster, like if you hit the fast 51 00:02:59,600 --> 00:03:02,760 Speaker 1: forward but and you'd be like, wow, now that's beautiful. Well, 52 00:03:02,800 --> 00:03:05,000 Speaker 1: I would like to hit the fastboard button and see 53 00:03:05,040 --> 00:03:07,040 Speaker 1: what happens to the university would answer a lot of 54 00:03:07,080 --> 00:03:09,800 Speaker 1: really fun questions. But I think there's also a lot 55 00:03:09,880 --> 00:03:13,640 Speaker 1: of beauty and taking some process that's dynamic, that's violent, 56 00:03:13,880 --> 00:03:16,480 Speaker 1: and then just freezing it. It's like looking at our 57 00:03:16,520 --> 00:03:19,800 Speaker 1: water drop hitting a surface and seeing those little mini 58 00:03:19,880 --> 00:03:23,040 Speaker 1: droplets in the ring come out. It captures something about 59 00:03:23,080 --> 00:03:24,880 Speaker 1: the physics that's happening in a way that I just 60 00:03:24,919 --> 00:03:29,000 Speaker 1: find beautiful. So lately you've been talking to an artist 61 00:03:29,240 --> 00:03:32,919 Speaker 1: right about this idea of beauty in the universe. Yeah, 62 00:03:32,960 --> 00:03:35,520 Speaker 1: that's right. We have some listeners who are scientists, and 63 00:03:35,560 --> 00:03:38,600 Speaker 1: listeners who are engineers, and also listeners who are rightists 64 00:03:38,600 --> 00:03:41,880 Speaker 1: and artists and cartoonists and of all stripes. And one 65 00:03:41,880 --> 00:03:43,800 Speaker 1: of them called me up recently and asked me what 66 00:03:43,880 --> 00:03:46,520 Speaker 1: I thought about the meaning of life and beauty in 67 00:03:46,560 --> 00:03:50,000 Speaker 1: the universe. And we had a really fascinating conversation. Wow, 68 00:03:50,240 --> 00:03:52,440 Speaker 1: what what do you have to say about the meaning 69 00:03:52,480 --> 00:03:55,400 Speaker 1: of life beauty in the universe? Sounds like a big question. 70 00:03:55,520 --> 00:03:58,560 Speaker 1: And the title of our next movie starting Juda Robbers 71 00:03:59,120 --> 00:04:02,600 Speaker 1: Life Beauty the Universe. Well, I think I said something 72 00:04:02,640 --> 00:04:05,400 Speaker 1: like scientists try to uncover beauty in the universe and 73 00:04:05,520 --> 00:04:08,720 Speaker 1: artists try to create it. Wow, but our artists part 74 00:04:08,760 --> 00:04:12,120 Speaker 1: of the universe. Yeah, and I guess that makes all artists. 75 00:04:13,160 --> 00:04:17,000 Speaker 1: I would agree with that, especially cartoonists. Yes, absolutely. But 76 00:04:17,080 --> 00:04:19,760 Speaker 1: she also asked me a really fascinating question. We were 77 00:04:19,800 --> 00:04:21,800 Speaker 1: like just about to get off the phone, and she said, 78 00:04:21,800 --> 00:04:24,240 Speaker 1: hold on a second, I have a question science question. 79 00:04:24,200 --> 00:04:27,000 Speaker 1: If you have always been curious about do you think 80 00:04:27,160 --> 00:04:30,000 Speaker 1: a lot of people have such a question that they've 81 00:04:30,040 --> 00:04:32,159 Speaker 1: always wanted to ask in case they ever talked to 82 00:04:32,200 --> 00:04:35,200 Speaker 1: a physicist. I don't know, I hope. So I think 83 00:04:35,240 --> 00:04:37,760 Speaker 1: everybody should be prepared. If you end up on an 84 00:04:37,760 --> 00:04:39,800 Speaker 1: airplane flight next to a physicist, you should be ready. 85 00:04:39,839 --> 00:04:43,000 Speaker 1: You should have that question in your pocket. But that 86 00:04:43,120 --> 00:04:45,479 Speaker 1: is a pretty great question. How do we know what 87 00:04:45,560 --> 00:04:47,960 Speaker 1: the shape of the Milky Way? Galaxia, Yeah, that was 88 00:04:47,960 --> 00:04:51,240 Speaker 1: her question. She said, we're inside the Milky Way, so 89 00:04:51,320 --> 00:04:53,560 Speaker 1: how is it that we can see pictures of the 90 00:04:53,680 --> 00:04:56,560 Speaker 1: Milky Way? Or more generally, how do we know the 91 00:04:56,600 --> 00:04:58,760 Speaker 1: shape of the Milky Way if we're stuck in the 92 00:04:58,760 --> 00:05:00,919 Speaker 1: middle of it? Right? Because I yes, we don't have 93 00:05:00,960 --> 00:05:05,920 Speaker 1: the equivalent of a galactic mirror. Right, we can't take 94 00:05:05,960 --> 00:05:08,880 Speaker 1: a selfie. So how do you know, like what your 95 00:05:08,920 --> 00:05:10,799 Speaker 1: nose looks like? Right? If you never had a mirror, 96 00:05:10,839 --> 00:05:12,560 Speaker 1: how would you know what your nose looks like? Yeah, 97 00:05:12,600 --> 00:05:15,240 Speaker 1: we need like a super long selfie stick, you know, 98 00:05:15,400 --> 00:05:17,400 Speaker 1: put a hubble on the edge of a stick that's 99 00:05:17,400 --> 00:05:19,680 Speaker 1: like a hundred thousand light years long to take a 100 00:05:19,720 --> 00:05:22,280 Speaker 1: picture of the Milky Way. That would take for a 101 00:05:22,279 --> 00:05:25,479 Speaker 1: long long time. So today we'll be answering this question 102 00:05:25,720 --> 00:05:28,680 Speaker 1: from one of our listeners. So today on the program, 103 00:05:28,720 --> 00:05:35,599 Speaker 1: we'll be asking the question how do we know the 104 00:05:35,760 --> 00:05:38,600 Speaker 1: shape of the Milky Way? And Daniel, it turns out 105 00:05:38,640 --> 00:05:41,159 Speaker 1: it has a very surprising shape, doesn't It does have 106 00:05:41,200 --> 00:05:43,359 Speaker 1: a weird shape. I think a lot of people have 107 00:05:43,400 --> 00:05:46,400 Speaker 1: an idea for what the Milky Way looks like. But 108 00:05:46,480 --> 00:05:48,479 Speaker 1: I was actually surprised when I dug into this to 109 00:05:48,520 --> 00:05:52,320 Speaker 1: discover it's not quite the shape that everybody expected. You know, 110 00:05:52,400 --> 00:05:56,000 Speaker 1: you just made me realize that most basically any picture 111 00:05:56,040 --> 00:05:57,880 Speaker 1: we've ever seen of the Milky Way was probably an 112 00:05:57,960 --> 00:06:00,680 Speaker 1: artist rendition. Oh I know, don't to even get me 113 00:06:00,720 --> 00:06:05,240 Speaker 1: started on artists renditions in astronomy. It's crazy. The renditions 114 00:06:05,240 --> 00:06:08,520 Speaker 1: are the artists probably both. But almost anytime you see 115 00:06:08,520 --> 00:06:11,360 Speaker 1: a new result in astronomy usually comes with some image, 116 00:06:11,360 --> 00:06:14,040 Speaker 1: and that image is not usually data. It's usually like 117 00:06:14,400 --> 00:06:18,040 Speaker 1: some artist rendition of how this might look, which includes 118 00:06:18,279 --> 00:06:22,200 Speaker 1: huge amounts of like it just invented stuff that's totally speculation, 119 00:06:22,520 --> 00:06:24,800 Speaker 1: and you can disentangle like what we know what it's 120 00:06:24,839 --> 00:06:27,960 Speaker 1: actually real from what like the artists just thought of 121 00:06:28,000 --> 00:06:30,520 Speaker 1: at three am when they were doodling on their computer. Right, 122 00:06:30,880 --> 00:06:33,320 Speaker 1: they should publish the data, right, Like, just show a 123 00:06:33,320 --> 00:06:35,520 Speaker 1: bunch of numbers. Yeah, at the top of the article. 124 00:06:35,960 --> 00:06:39,400 Speaker 1: I'm sure a lot of people would click on that. Well. 125 00:06:39,440 --> 00:06:41,800 Speaker 1: I think the data itself is fascinating. Think about the 126 00:06:41,800 --> 00:06:44,600 Speaker 1: picture of the black hole. That's fascinating to see an 127 00:06:44,600 --> 00:06:47,599 Speaker 1: actual picture of an actual black hole. The zillions of 128 00:06:47,680 --> 00:06:50,640 Speaker 1: artistic images of black holes. But there's only one truth, 129 00:06:50,880 --> 00:06:52,640 Speaker 1: and we want to know the truth, not just like 130 00:06:52,800 --> 00:06:56,200 Speaker 1: what some artists imagined. Imagine if particle physics we just 131 00:06:56,240 --> 00:07:00,279 Speaker 1: like published artists impressions of data from the collision, you know, 132 00:07:01,040 --> 00:07:03,920 Speaker 1: instead of actual data, we would get tossed out of science. 133 00:07:03,920 --> 00:07:06,359 Speaker 1: As like you said, Daniel, that artists do capture truth. 134 00:07:07,720 --> 00:07:09,600 Speaker 1: I think they create beauty. I don't know if it's 135 00:07:09,600 --> 00:07:14,680 Speaker 1: always true. It's not always true. That day succeed all right, 136 00:07:15,760 --> 00:07:17,960 Speaker 1: all right, well, this is an interesting question. How do 137 00:07:18,000 --> 00:07:20,120 Speaker 1: you know what the shape of the Milky Way is 138 00:07:20,160 --> 00:07:23,560 Speaker 1: if you are standing in the middle of it and 139 00:07:23,760 --> 00:07:25,480 Speaker 1: or at least off to a little bit of a 140 00:07:25,520 --> 00:07:28,200 Speaker 1: corner of it. So, as usual, Daniel went out there 141 00:07:28,240 --> 00:07:30,880 Speaker 1: into the wilds of the internet to ask people if 142 00:07:30,960 --> 00:07:34,560 Speaker 1: they knew how we know the shape of the Milky Way? 143 00:07:34,720 --> 00:07:37,920 Speaker 1: And so if you like to participate in future baseless 144 00:07:37,920 --> 00:07:41,160 Speaker 1: speculation with that research on topics of the day. Please 145 00:07:41,320 --> 00:07:44,239 Speaker 1: write to us. And also, if you have a question 146 00:07:44,280 --> 00:07:46,880 Speaker 1: for a physicist you've never had a chance to ask, 147 00:07:47,000 --> 00:07:50,320 Speaker 1: please write to us two questions at Daniel and Jorge 148 00:07:50,440 --> 00:07:53,080 Speaker 1: dot com. We love our listener emails and we really 149 00:07:53,080 --> 00:07:55,400 Speaker 1: do respond to every single one. We should change the 150 00:07:55,440 --> 00:08:00,680 Speaker 1: name of the podcast Daniel to baseless speculation. I think 151 00:08:00,680 --> 00:08:06,240 Speaker 1: that's implied already in physics or in our podcasts Daniel 152 00:08:06,280 --> 00:08:09,840 Speaker 1: and Jorge, so it must include baseless speculation. Yeah, so 153 00:08:09,880 --> 00:08:11,640 Speaker 1: I think about it for a second. Do you know 154 00:08:11,800 --> 00:08:14,080 Speaker 1: how we know the shape of the milk way? What 155 00:08:14,160 --> 00:08:17,720 Speaker 1: would you answer? It's what people had to say. I 156 00:08:17,800 --> 00:08:22,440 Speaker 1: believe our galaxy is relatively flat. So I assume if 157 00:08:22,480 --> 00:08:29,320 Speaker 1: you aim a telescope through the galaxy and then raise 158 00:08:29,400 --> 00:08:31,720 Speaker 1: it above or below the plane of our galaxy, you 159 00:08:31,760 --> 00:08:35,120 Speaker 1: can see there's nothing there. So the natural conclusion is 160 00:08:35,120 --> 00:08:37,280 Speaker 1: that the oxy is rather flat. I would guess that 161 00:08:37,360 --> 00:08:40,680 Speaker 1: the way we moved the shape our galaxy is by 162 00:08:40,960 --> 00:08:43,920 Speaker 1: using all the telescopes that we have, such as Hubble, 163 00:08:45,200 --> 00:08:49,640 Speaker 1: and looking at the whole range of radiation from UV 164 00:08:49,960 --> 00:08:53,800 Speaker 1: to visible lights, two X and gamma rays, and making 165 00:08:53,880 --> 00:08:57,520 Speaker 1: up an image of our galaxy. I think it is 166 00:08:58,840 --> 00:09:03,840 Speaker 1: by scientists and astronomers looking at distant stars in our 167 00:09:03,880 --> 00:09:09,120 Speaker 1: own galaxy and trying to uh map the distance. And 168 00:09:09,240 --> 00:09:13,080 Speaker 1: we also can observe the band of light in the 169 00:09:13,320 --> 00:09:16,960 Speaker 1: in the clear dark sky, which looks like, you know, 170 00:09:17,679 --> 00:09:20,439 Speaker 1: a straight line. And also more importantly, I think we 171 00:09:20,520 --> 00:09:24,959 Speaker 1: have observed distant galaxies and then we can see that 172 00:09:25,040 --> 00:09:29,120 Speaker 1: most galaxies are spiral. I'm assuming that it's mostly just 173 00:09:29,240 --> 00:09:35,160 Speaker 1: from you know, the telescope images and knowing where the 174 00:09:35,280 --> 00:09:38,760 Speaker 1: large sources of mass and our galaxy are, and performing 175 00:09:39,280 --> 00:09:42,200 Speaker 1: models and looking at gravity and to figure out what 176 00:09:42,320 --> 00:09:45,240 Speaker 1: kind of shape that's best. That's a tough one. I'm 177 00:09:45,280 --> 00:09:49,040 Speaker 1: honestly not really a hun percent sure. I do know, 178 00:09:49,800 --> 00:09:53,920 Speaker 1: just like from an energy perspective, I believe the shape 179 00:09:54,000 --> 00:09:57,880 Speaker 1: is um, you know, saddle, and I think it has 180 00:09:57,920 --> 00:10:01,560 Speaker 1: to do with offsetting energy. I don't know many clever 181 00:10:01,720 --> 00:10:09,000 Speaker 1: people fearing out how stars move around the center of 182 00:10:09,040 --> 00:10:13,480 Speaker 1: the galaxy, and that's that gives us a clue of 183 00:10:13,840 --> 00:10:17,880 Speaker 1: how everything is organized around us. All right, people had 184 00:10:18,160 --> 00:10:21,160 Speaker 1: some pretty good ideas here. Nobody said I don't know, 185 00:10:21,320 --> 00:10:25,320 Speaker 1: or that sounds impossible, right, Well, I think people know 186 00:10:25,360 --> 00:10:27,800 Speaker 1: that we've mostly figured it out, and so they imagine 187 00:10:27,840 --> 00:10:30,959 Speaker 1: there must be a way to do it. Oh. Interesting, 188 00:10:31,240 --> 00:10:36,120 Speaker 1: they just assume we figured it out many clever people. Yeah, 189 00:10:36,120 --> 00:10:39,480 Speaker 1: I guess nobody assumed that all this time physicists have 190 00:10:39,600 --> 00:10:42,640 Speaker 1: been making stuff up. It's just been an artist's impression 191 00:10:42,679 --> 00:10:46,160 Speaker 1: this entire time, this entire time. Yeah, Actually, the Milky 192 00:10:46,160 --> 00:10:49,720 Speaker 1: Way looks like a w or x. It's a top hat. 193 00:10:51,840 --> 00:10:54,520 Speaker 1: It looks like a glass of milk. Actually. Yeah, So 194 00:10:54,559 --> 00:10:56,960 Speaker 1: that's an interesting question because we are in the middle 195 00:10:56,960 --> 00:10:59,480 Speaker 1: of the galaxy, right or you know, a little bit 196 00:10:59,520 --> 00:11:01,760 Speaker 1: off to this, but we're not like very far away 197 00:11:01,800 --> 00:11:03,320 Speaker 1: from it, so we don't have a view of it. 198 00:11:03,520 --> 00:11:05,040 Speaker 1: So it's kind of hard to tell. I mean, when 199 00:11:05,040 --> 00:11:07,600 Speaker 1: you look out, you see a cloud of stars. Yeah, 200 00:11:07,640 --> 00:11:09,840 Speaker 1: when you look out, you just see a cloud of stars. 201 00:11:09,880 --> 00:11:12,440 Speaker 1: And that's why it took us actually a long time 202 00:11:12,480 --> 00:11:14,240 Speaker 1: to figure out the shape of the Milky Way. It's 203 00:11:14,240 --> 00:11:18,280 Speaker 1: something we've only recently understood, even like at its broadest scale. 204 00:11:18,400 --> 00:11:21,880 Speaker 1: You know, like people thousands of years ago didn't understand 205 00:11:21,960 --> 00:11:24,320 Speaker 1: the shape of the Milky Way. It's a modern idea 206 00:11:24,679 --> 00:11:27,080 Speaker 1: that the Milky Way is this spiral disk I guess 207 00:11:27,120 --> 00:11:29,120 Speaker 1: it'd be like, you know, trying to guess what the 208 00:11:29,160 --> 00:11:32,120 Speaker 1: shape of the Pacific Ocean is if you're a fish. 209 00:11:32,559 --> 00:11:35,600 Speaker 1: That kind of hard. Do you think fish wonder about that? 210 00:11:36,640 --> 00:11:39,320 Speaker 1: I don't think they want to know, you know. I 211 00:11:39,400 --> 00:11:43,360 Speaker 1: bet fish artists are constantly drawing images of the shape 212 00:11:43,360 --> 00:11:46,360 Speaker 1: of the Pacific Ocean that are just totally baseless speculation 213 00:11:46,960 --> 00:11:50,200 Speaker 1: for their knees articles. Yeah, and I'm sure the fishes 214 00:11:50,640 --> 00:11:54,000 Speaker 1: have a real problem with that, I know on their 215 00:11:54,000 --> 00:11:57,040 Speaker 1: fish casts. Yeah. So, um, it's a pretty interesting question. 216 00:11:57,080 --> 00:11:58,760 Speaker 1: And I guess we figured it out. And so the 217 00:11:58,840 --> 00:12:00,560 Speaker 1: question is how did we figure out out? What is 218 00:12:00,559 --> 00:12:03,800 Speaker 1: the shape of the Milky Way galaxy? So Daniel step 219 00:12:03,880 --> 00:12:06,040 Speaker 1: us through what is kind of a history of this? 220 00:12:06,160 --> 00:12:08,400 Speaker 1: Why did we realize we are in a galaxy? First 221 00:12:08,400 --> 00:12:11,160 Speaker 1: of all, those are two actually fascinating but different questions. 222 00:12:11,200 --> 00:12:13,400 Speaker 1: Like people have looked up in the night sky and 223 00:12:13,840 --> 00:12:16,600 Speaker 1: seeing this band, this thing we call the Milky win 224 00:12:16,640 --> 00:12:19,120 Speaker 1: the night sky, this band of light that looks like 225 00:12:19,160 --> 00:12:22,240 Speaker 1: spilled milk that people have seen obviously for thousands of years. 226 00:12:22,280 --> 00:12:24,839 Speaker 1: For that you only need eyeballs, And people have been 227 00:12:24,840 --> 00:12:27,920 Speaker 1: wondering like what is that, you know, and It was 228 00:12:28,040 --> 00:12:31,079 Speaker 1: only like around the time of Galileo, when we had 229 00:12:31,080 --> 00:12:34,400 Speaker 1: telescopes that people realized it wasn't just some sort of 230 00:12:34,440 --> 00:12:37,120 Speaker 1: gas or some sort of fire in the sky, but 231 00:12:37,160 --> 00:12:41,439 Speaker 1: it was actually made of zillions of tiny little stars. 232 00:12:41,440 --> 00:12:44,880 Speaker 1: So that idea there is only a few hundred years old. Wow, 233 00:12:45,040 --> 00:12:47,360 Speaker 1: So how did Galileo figure it out? I mean, when 234 00:12:47,400 --> 00:12:49,520 Speaker 1: you look at the Milky Way with a telescope, you 235 00:12:49,520 --> 00:12:52,400 Speaker 1: can actually see the individual dots or you just see 236 00:12:52,400 --> 00:12:55,000 Speaker 1: a concentration of dots kind of in that area. Well both. 237 00:12:55,040 --> 00:12:56,959 Speaker 1: I mean, it gets denser in some regions and it's 238 00:12:56,960 --> 00:12:58,880 Speaker 1: dimmer in other regions, but you can look at the 239 00:12:58,960 --> 00:13:01,080 Speaker 1: edges of it and you can see that that cloud 240 00:13:01,160 --> 00:13:03,560 Speaker 1: is really just made up a lot of tiny little dots. 241 00:13:03,600 --> 00:13:06,160 Speaker 1: And of course, the more powerful your telescope, the more 242 00:13:06,240 --> 00:13:09,079 Speaker 1: you can resolve the denser and denser regions. But at 243 00:13:09,080 --> 00:13:11,600 Speaker 1: that time, I'm guessing gilly Little didn't know we were 244 00:13:11,920 --> 00:13:14,080 Speaker 1: in a galaxy or what a galaxy was, right, Like, 245 00:13:14,080 --> 00:13:17,080 Speaker 1: he probably just thought there's a there's a weird concentration 246 00:13:17,120 --> 00:13:19,600 Speaker 1: of stars along this line. Yeah, we didn't even have 247 00:13:19,640 --> 00:13:21,720 Speaker 1: the idea of a galaxy. We just thought, well, there 248 00:13:21,800 --> 00:13:24,200 Speaker 1: was just a universe and it was filled with stars. 249 00:13:24,480 --> 00:13:28,120 Speaker 1: And the whole idea of that stars were clumped into galaxies, 250 00:13:28,320 --> 00:13:31,880 Speaker 1: these little like island universes, they called them, originally came 251 00:13:31,920 --> 00:13:35,000 Speaker 1: about only about a hundred years ago when people started 252 00:13:35,040 --> 00:13:38,560 Speaker 1: measuring the distances to these other faint little smudges, like 253 00:13:38,800 --> 00:13:41,120 Speaker 1: you have the big Milky Way or at this huge 254 00:13:41,200 --> 00:13:43,880 Speaker 1: spilled milk in the sky, and people understood, oh, that's 255 00:13:43,920 --> 00:13:46,480 Speaker 1: just a bunch of stars. But then people also saw 256 00:13:46,559 --> 00:13:49,559 Speaker 1: these little smudges that they couldn't quite resolve that looked 257 00:13:49,559 --> 00:13:52,800 Speaker 1: like distant gas clouds, and they thought, oh, these are 258 00:13:52,840 --> 00:13:56,160 Speaker 1: other just you know, gas clouds that are fairly nearby um. 259 00:13:56,200 --> 00:13:58,160 Speaker 1: And it wasn't until about a hundred years ago that 260 00:13:58,200 --> 00:14:01,600 Speaker 1: they realized that those were entire different galaxies that were 261 00:14:01,720 --> 00:14:05,040 Speaker 1: super far away. And that's sort of the origin of 262 00:14:05,080 --> 00:14:08,240 Speaker 1: this idea that we are a cluster of stars gathered 263 00:14:08,280 --> 00:14:11,480 Speaker 1: together into this little island in space. Right. What year 264 00:14:11,559 --> 00:14:13,760 Speaker 1: was that? That was in about nineteen twenty. That was 265 00:14:13,800 --> 00:14:16,560 Speaker 1: the year of the Great Debate in astronomy, when there 266 00:14:16,559 --> 00:14:19,520 Speaker 1: were folks arguing that the Milky Way basically was the 267 00:14:19,520 --> 00:14:22,720 Speaker 1: whole universe and those little smudges were just gas clouds 268 00:14:22,720 --> 00:14:24,960 Speaker 1: in the Milky Way, and other folks arguing that the 269 00:14:24,960 --> 00:14:27,400 Speaker 1: Milky Way was just a little island and those smudges 270 00:14:27,560 --> 00:14:31,480 Speaker 1: were other distant galaxies. So even in nineteen twenty there 271 00:14:31,520 --> 00:14:34,320 Speaker 1: was a huge debate about that, and that's around the 272 00:14:34,360 --> 00:14:36,520 Speaker 1: time when we started to kind of get a sense 273 00:14:36,520 --> 00:14:38,760 Speaker 1: of the shape of the Milky Way. Right, Yeah, exactly, 274 00:14:38,760 --> 00:14:41,920 Speaker 1: because the whole idea, the basic concept for how you 275 00:14:41,960 --> 00:14:44,840 Speaker 1: build a map for something you're inside of, is that 276 00:14:44,880 --> 00:14:48,000 Speaker 1: you need to measure the distances to the things you're seeing. 277 00:14:48,440 --> 00:14:50,120 Speaker 1: But if you're just looking at the night sky and 278 00:14:50,120 --> 00:14:52,120 Speaker 1: you seeing a bunch of pin pricks, you can't tell 279 00:14:52,160 --> 00:14:55,160 Speaker 1: the difference between lots of different shapes. Is everything far 280 00:14:55,240 --> 00:14:58,240 Speaker 1: away and really bright? Is everything close by and not 281 00:14:58,360 --> 00:15:01,040 Speaker 1: that bright? Are some things far and something's close. It's 282 00:15:01,040 --> 00:15:03,160 Speaker 1: really hard to tell if you don't know the distances. 283 00:15:03,240 --> 00:15:05,920 Speaker 1: So you have to build basically a three D map 284 00:15:06,160 --> 00:15:10,160 Speaker 1: to everything you're seeing from the inside. And that started 285 00:15:10,160 --> 00:15:13,040 Speaker 1: to happen only when we develop better techniques for measuring 286 00:15:13,080 --> 00:15:16,800 Speaker 1: the distances. Two stars, right, because from where we are, 287 00:15:16,840 --> 00:15:19,640 Speaker 1: all stars look like little pinpoints, right, It's not like 288 00:15:19,960 --> 00:15:22,640 Speaker 1: stars that are closer to us actually looked like a circle. 289 00:15:22,880 --> 00:15:26,440 Speaker 1: Everything is so far away that everything looks like a pinpoint. Basically, Yeah, 290 00:15:26,480 --> 00:15:28,320 Speaker 1: the only things that you can actually resolve in the 291 00:15:28,400 --> 00:15:31,760 Speaker 1: telescope are planets and things in our solar system. Everything 292 00:15:31,800 --> 00:15:34,080 Speaker 1: else is so far away that it looks just like 293 00:15:34,120 --> 00:15:37,200 Speaker 1: a point. Remember, the nearest star is more than four 294 00:15:37,400 --> 00:15:39,800 Speaker 1: light years away, so there's no way you're going to 295 00:15:39,920 --> 00:15:41,920 Speaker 1: see the difference between like the left side of the 296 00:15:41,960 --> 00:15:43,920 Speaker 1: star and the right side of the star, and you 297 00:15:43,920 --> 00:15:46,400 Speaker 1: can't resolve it. And even if you could, that wouldn't 298 00:15:46,440 --> 00:15:49,280 Speaker 1: tell you necessarily how far away it was because you 299 00:15:49,280 --> 00:15:51,880 Speaker 1: wouldn't have any recognizable features on it to give you 300 00:15:51,920 --> 00:15:54,600 Speaker 1: a sense of scale, So you still wouldn't know is 301 00:15:54,600 --> 00:15:57,520 Speaker 1: it close by and pretty small or really far away 302 00:15:57,760 --> 00:16:00,320 Speaker 1: and huge. And that was actually the question of about 303 00:16:00,360 --> 00:16:02,760 Speaker 1: these nebula. I mean, with the nebula, you can see 304 00:16:02,800 --> 00:16:04,760 Speaker 1: the left and the right side of it, these smudges, 305 00:16:05,080 --> 00:16:08,040 Speaker 1: and people were wondering are they close by and pretty 306 00:16:08,040 --> 00:16:13,080 Speaker 1: big or really far away and incredibly enormous. And that 307 00:16:13,160 --> 00:16:16,160 Speaker 1: was one argument actually against the idea that these nebula 308 00:16:16,440 --> 00:16:19,600 Speaker 1: other galaxies. People thought, if there are other galaxies, they 309 00:16:19,640 --> 00:16:23,760 Speaker 1: must be just like unfathomily far away and really really big. 310 00:16:24,360 --> 00:16:26,560 Speaker 1: So yeah, you definitely need some sort of system to 311 00:16:26,600 --> 00:16:29,480 Speaker 1: measure the distance to these things, because you can't just 312 00:16:29,600 --> 00:16:32,360 Speaker 1: look at a star and tell how far away it is. Yeah, okay, 313 00:16:32,360 --> 00:16:34,440 Speaker 1: So then how did we start to get a sense 314 00:16:34,520 --> 00:16:36,440 Speaker 1: of the shape of the Milky Way? Did we just 315 00:16:36,440 --> 00:16:40,520 Speaker 1: start looking out into the swirl and gave us somehow 316 00:16:40,560 --> 00:16:43,440 Speaker 1: a sense of the shape of it. Yeah, it dates back, 317 00:16:43,520 --> 00:16:45,760 Speaker 1: you know, more than a hundred years. People just sort 318 00:16:45,760 --> 00:16:48,160 Speaker 1: of started looking at stars and trying to get a map. 319 00:16:48,600 --> 00:16:51,840 Speaker 1: And the way you can tell the distance to nearby stars. 320 00:16:52,200 --> 00:16:55,600 Speaker 1: He's using something called parallax, which means you look at 321 00:16:55,640 --> 00:16:57,840 Speaker 1: the star when we're on one side of the sun, 322 00:16:58,080 --> 00:17:00,840 Speaker 1: and then again when we are on the other side 323 00:17:00,880 --> 00:17:03,120 Speaker 1: of the sun, and that gives you a sense based 324 00:17:03,160 --> 00:17:05,880 Speaker 1: on how much it moves in the sky how far 325 00:17:05,920 --> 00:17:08,280 Speaker 1: away it is. It's sort of like putting your finger 326 00:17:08,480 --> 00:17:10,679 Speaker 1: at arms length and then looking at it through your 327 00:17:10,760 --> 00:17:13,240 Speaker 1: left eye or your right eye. You can see that 328 00:17:13,320 --> 00:17:16,120 Speaker 1: it changes, and then as your finger gets closer and closer, 329 00:17:16,160 --> 00:17:18,640 Speaker 1: it makes a bigger and bigger difference. So by how 330 00:17:18,720 --> 00:17:21,400 Speaker 1: much your view changes as you look from one eye 331 00:17:21,400 --> 00:17:23,800 Speaker 1: to the other you can tell how far away something is. 332 00:17:23,840 --> 00:17:27,080 Speaker 1: It's binocular vision, right, So that was the first idea 333 00:17:27,240 --> 00:17:31,040 Speaker 1: to use parallax to measure the distance to fairly nearby stars. Wow, 334 00:17:31,240 --> 00:17:33,920 Speaker 1: and how well does that work? It works pretty well 335 00:17:33,960 --> 00:17:37,119 Speaker 1: for stars up to you know, ten twenty fifty light 336 00:17:37,200 --> 00:17:40,400 Speaker 1: years maybe, But there's a problem and that it only 337 00:17:40,440 --> 00:17:43,600 Speaker 1: really lets you see pretty nearby stars, stars that are 338 00:17:43,640 --> 00:17:46,960 Speaker 1: bright enough, and stars that can penetrate like the interstellar 339 00:17:47,080 --> 00:17:50,240 Speaker 1: fog of the gas and the dust. So the first 340 00:17:50,280 --> 00:17:52,280 Speaker 1: ideas we had of the shape of the Milky Way 341 00:17:52,280 --> 00:17:55,000 Speaker 1: where oh, it's basically a blob and we're in the 342 00:17:55,000 --> 00:17:58,000 Speaker 1: middle of it, because that's what happens when you're standing 343 00:17:58,000 --> 00:18:00,399 Speaker 1: in a fog. Like imagine you're in a crowd of 344 00:18:00,400 --> 00:18:02,919 Speaker 1: people in a fog. You look around, you think, oh, 345 00:18:03,119 --> 00:18:05,680 Speaker 1: I'm at the center of this crowd, right, But everybody 346 00:18:05,680 --> 00:18:07,880 Speaker 1: thinks that because they have a limited vision, crock could 347 00:18:07,920 --> 00:18:10,399 Speaker 1: look like a hot dog or a top hat. Right. 348 00:18:10,480 --> 00:18:13,119 Speaker 1: You never know, Yeah, you'd never know. And so what 349 00:18:13,160 --> 00:18:14,760 Speaker 1: we have to do is develop a way to see 350 00:18:14,840 --> 00:18:17,960 Speaker 1: further away stars, to see out to the edges of 351 00:18:18,000 --> 00:18:20,480 Speaker 1: the Milky Way, to find something really bright that we 352 00:18:20,480 --> 00:18:23,000 Speaker 1: could calibrate that we could figure out how far away 353 00:18:23,000 --> 00:18:25,080 Speaker 1: it is, and that let us get a sense for 354 00:18:25,119 --> 00:18:28,000 Speaker 1: the shape of the Milky Way. All right, let's get 355 00:18:28,000 --> 00:18:32,080 Speaker 1: into how we finally cracked this method for measuring the 356 00:18:32,119 --> 00:18:35,480 Speaker 1: shape of the galaxy and what the shape actually is. 357 00:18:35,960 --> 00:18:50,200 Speaker 1: But first let's take a quick break. All right, we're 358 00:18:50,200 --> 00:18:52,919 Speaker 1: asking the question how do we know the shape of 359 00:18:52,960 --> 00:18:56,119 Speaker 1: the Milky Way? And Daniel so, so far we have 360 00:18:56,280 --> 00:19:00,159 Speaker 1: one method for telling how far stars are, but it 361 00:19:00,200 --> 00:19:03,000 Speaker 1: doesn't get us far enough. So how do we know 362 00:19:03,200 --> 00:19:05,160 Speaker 1: what the shape of the blob of stars that were 363 00:19:05,200 --> 00:19:08,119 Speaker 1: in looks like? So we take advantage of some really weird, 364 00:19:08,440 --> 00:19:12,480 Speaker 1: really lucky stars. It's almost like somebody has sprinkled these 365 00:19:12,520 --> 00:19:15,359 Speaker 1: stars out there precisely to allow us to measure the 366 00:19:15,440 --> 00:19:18,199 Speaker 1: distance to them. It's amazing how perfectly they work for 367 00:19:18,280 --> 00:19:21,440 Speaker 1: exactly this purpose. So it has to do something with 368 00:19:21,560 --> 00:19:24,480 Speaker 1: a special kind of star. There's a special kind of star. Now, 369 00:19:24,480 --> 00:19:27,800 Speaker 1: a normal star burns at the same brightness all the time, 370 00:19:27,920 --> 00:19:30,880 Speaker 1: and so you can't tell the difference between it being 371 00:19:30,960 --> 00:19:33,800 Speaker 1: really far away and super bright or it being close 372 00:19:33,920 --> 00:19:36,800 Speaker 1: up and fairly dim. But there's another kind of star, 373 00:19:36,960 --> 00:19:41,280 Speaker 1: a variable star whose brightness changes week to week and 374 00:19:41,400 --> 00:19:44,280 Speaker 1: month to month. These are called sephids, and they're first 375 00:19:44,320 --> 00:19:49,119 Speaker 1: discovered by famous female astronomer Henrietta Levitt. And so on 376 00:19:49,160 --> 00:19:51,800 Speaker 1: the time scale like days or months, they get brighter 377 00:19:51,840 --> 00:19:53,800 Speaker 1: and then they get dimmer, and they get brighter and 378 00:19:53,800 --> 00:19:57,600 Speaker 1: then they get dimmer, right, And that tells us a 379 00:19:57,640 --> 00:20:00,760 Speaker 1: little bit about where it is the frequen or is 380 00:20:00,800 --> 00:20:02,919 Speaker 1: it more like we know that these stars are all 381 00:20:02,960 --> 00:20:06,480 Speaker 1: about the same size. They're not all about the same size, 382 00:20:06,600 --> 00:20:10,280 Speaker 1: But there's a really key relationship. There's a connection between 383 00:20:10,359 --> 00:20:13,520 Speaker 1: how quickly they change, like the period between going from 384 00:20:13,560 --> 00:20:16,840 Speaker 1: brightest to dimmest. There's a close connection between that time 385 00:20:17,440 --> 00:20:20,520 Speaker 1: and the brightness of the star, the actual brightness of 386 00:20:20,560 --> 00:20:23,440 Speaker 1: the star. And so while you can't measure how bright 387 00:20:23,480 --> 00:20:25,200 Speaker 1: this star would be if you were standing right next 388 00:20:25,200 --> 00:20:27,919 Speaker 1: to it, you can measure how long it takes to 389 00:20:27,920 --> 00:20:30,679 Speaker 1: go from its brightest to its dimmest. And what they 390 00:20:30,720 --> 00:20:33,800 Speaker 1: discovered when they looked at nearby sephids ones that they 391 00:20:33,840 --> 00:20:36,800 Speaker 1: could measure the distance to using other techniques was that 392 00:20:36,840 --> 00:20:40,639 Speaker 1: there was this incredible relationship, this very clean relationship. So 393 00:20:40,720 --> 00:20:43,960 Speaker 1: if you measured the period, you could extract the luminosity. 394 00:20:44,080 --> 00:20:45,960 Speaker 1: If you knew how long it took to go from 395 00:20:46,040 --> 00:20:49,760 Speaker 1: bright to dim and back, you could then calculate how 396 00:20:49,800 --> 00:20:52,840 Speaker 1: bright it actually was. Oh, I see, that's pretty clever. 397 00:20:52,960 --> 00:20:55,760 Speaker 1: It's like we and I guess we use parallel axes, 398 00:20:55,960 --> 00:20:58,600 Speaker 1: is what they would use to sort of calibrate all this. 399 00:20:58,760 --> 00:21:03,680 Speaker 1: Like we using parallax. We figured out that close by 400 00:21:04,040 --> 00:21:09,080 Speaker 1: sephids are brighter when they blink faster or something like that. 401 00:21:09,080 --> 00:21:11,080 Speaker 1: That's right. We use the close by ones, the ones 402 00:21:11,119 --> 00:21:14,760 Speaker 1: where we could measure their brightness and their actual distance 403 00:21:14,840 --> 00:21:18,240 Speaker 1: using parallax, And we figured out that there's this relationship 404 00:21:18,440 --> 00:21:21,320 Speaker 1: between the period and the luminosity. And if you know 405 00:21:21,520 --> 00:21:24,360 Speaker 1: the actual brightness of a star and you can measure 406 00:21:24,440 --> 00:21:26,600 Speaker 1: the brightness here on Earth, then you can tell how 407 00:21:26,640 --> 00:21:29,400 Speaker 1: far away it is, because everything goes by one over 408 00:21:29,480 --> 00:21:32,480 Speaker 1: our squared, Like the further you are away from the star, 409 00:21:32,800 --> 00:21:35,080 Speaker 1: the dimm or it will be. But that's something that's 410 00:21:35,160 --> 00:21:38,480 Speaker 1: very simple and easy to understand. Twice as far away 411 00:21:38,880 --> 00:21:41,840 Speaker 1: be four times as dim. You're ten times as far away, 412 00:21:41,880 --> 00:21:44,199 Speaker 1: it will be a hundred times as dim. So if 413 00:21:44,200 --> 00:21:46,679 Speaker 1: you know the actual brightness, you know the brightness that 414 00:21:46,720 --> 00:21:49,639 Speaker 1: you measure here you can figure out how far away 415 00:21:49,640 --> 00:21:52,240 Speaker 1: from it you must be, right. That's pretty clever. And 416 00:21:52,280 --> 00:21:54,800 Speaker 1: so that's our main method for getting the shape of 417 00:21:54,800 --> 00:21:57,720 Speaker 1: the galaxy, Like just going by these stars. That's our 418 00:21:57,720 --> 00:22:00,960 Speaker 1: main method. Yea. The sefid stars really are the key, 419 00:22:01,040 --> 00:22:03,920 Speaker 1: and we can see them because they're super duper bright. 420 00:22:04,200 --> 00:22:07,080 Speaker 1: Like some of these stars are like ten thousand times 421 00:22:07,119 --> 00:22:10,400 Speaker 1: brighter than the Sun, so they can penetrate through those 422 00:22:10,400 --> 00:22:12,960 Speaker 1: clouds of gas and dust and you can see them 423 00:22:13,000 --> 00:22:15,600 Speaker 1: even on the other side of the Milky Way. Well, 424 00:22:15,680 --> 00:22:18,640 Speaker 1: sometimes there are ten thousand times brighter, sometimes they're demmer. 425 00:22:19,720 --> 00:22:22,800 Speaker 1: On a good day, they're so bright that you can 426 00:22:22,840 --> 00:22:25,919 Speaker 1: see them in other galaxies. That was the clue that 427 00:22:26,000 --> 00:22:29,800 Speaker 1: Hubble needed to understand that these nebula, these little smudges 428 00:22:29,840 --> 00:22:33,200 Speaker 1: in space, were super duper far away, because he saw 429 00:22:33,240 --> 00:22:36,840 Speaker 1: these sephids varying in other galaxies, like you can see 430 00:22:36,840 --> 00:22:40,399 Speaker 1: sefids in Andromeda. You can see them in other galaxies 431 00:22:40,600 --> 00:22:43,200 Speaker 1: blinking on and off and telling us how far away 432 00:22:43,240 --> 00:22:46,160 Speaker 1: it was. Really. Yeah, like within this mug there would 433 00:22:46,160 --> 00:22:49,119 Speaker 1: be like a little pixel that turned on and off, Yes, exactly. 434 00:22:49,440 --> 00:22:51,800 Speaker 1: And that's the key that told them that these nebula 435 00:22:51,840 --> 00:22:55,920 Speaker 1: were not just pretty big gas clouds inside our galaxies, 436 00:22:56,040 --> 00:23:00,320 Speaker 1: but actually entire other galaxies because his distance measurements put 437 00:23:00,359 --> 00:23:03,439 Speaker 1: them much further away than anything else we saw in 438 00:23:03,480 --> 00:23:06,600 Speaker 1: the sky. It's like if you map the stuff around 439 00:23:06,640 --> 00:23:08,440 Speaker 1: you and you find there's an edge and then there's 440 00:23:08,480 --> 00:23:11,840 Speaker 1: a huge gap, and they see these other dots. That's 441 00:23:11,840 --> 00:23:15,800 Speaker 1: what gives you this like island universe picture of our cosmos. 442 00:23:16,080 --> 00:23:18,440 Speaker 1: It's not just a bunch of stars sprinkled through space 443 00:23:18,440 --> 00:23:21,080 Speaker 1: which with occasional clumping, but that there are these little 444 00:23:21,119 --> 00:23:25,280 Speaker 1: localized blobs which we now called galaxies, these island universes. 445 00:23:25,560 --> 00:23:27,960 Speaker 1: It's almost like somebody on purpose put a bunch of 446 00:23:28,000 --> 00:23:31,240 Speaker 1: light posts all over the universe for us to see 447 00:23:31,280 --> 00:23:33,920 Speaker 1: what the shape and the structures of it are. It's 448 00:23:34,000 --> 00:23:37,639 Speaker 1: really incredible. Without sephids, we would know so much less 449 00:23:37,680 --> 00:23:40,600 Speaker 1: about the nature of the universe. Now recently we've developed 450 00:23:40,640 --> 00:23:43,480 Speaker 1: even more powerful techniques to do sort of the same 451 00:23:43,480 --> 00:23:46,480 Speaker 1: thing on a grander scale. See Deeper into the Universe, 452 00:23:46,840 --> 00:23:49,520 Speaker 1: And we talked to another podcast about the whole structure 453 00:23:50,000 --> 00:23:53,320 Speaker 1: of our cosmos, the large scale structure like where galaxies 454 00:23:53,400 --> 00:23:56,320 Speaker 1: themselves are distributed, and for that we use type one 455 00:23:56,359 --> 00:23:59,240 Speaker 1: a supernova, which is another space object in the same 456 00:23:59,320 --> 00:24:02,000 Speaker 1: kind of category ory where by watching it from far 457 00:24:02,040 --> 00:24:05,040 Speaker 1: away you can tell how bright it actually is and 458 00:24:05,080 --> 00:24:07,960 Speaker 1: then you can figure out how far away it must be. 459 00:24:08,000 --> 00:24:10,840 Speaker 1: But sepids are sort of like the middle ground. Parallax 460 00:24:10,920 --> 00:24:13,359 Speaker 1: is for really close stuff, sefids is for sort of 461 00:24:13,400 --> 00:24:17,400 Speaker 1: intermediate and type one a supernova take you the furthest distance. 462 00:24:17,760 --> 00:24:19,720 Speaker 1: But when it comes to mapping the Milky Way, it's 463 00:24:19,760 --> 00:24:22,800 Speaker 1: really the sefids that are leading the charge, and they're 464 00:24:22,800 --> 00:24:25,439 Speaker 1: sort of amazing, Like you might wonder, like, why is 465 00:24:25,480 --> 00:24:28,640 Speaker 1: the star blinking on and off so regularly? Yeah, it's 466 00:24:28,640 --> 00:24:30,399 Speaker 1: almost like we don't really have a picture of the 467 00:24:30,440 --> 00:24:32,920 Speaker 1: real Milky Way. We just have a picture of sefond 468 00:24:32,960 --> 00:24:35,760 Speaker 1: Milky Way. Have they sort of map out? It's like tracers, right, 469 00:24:36,080 --> 00:24:37,840 Speaker 1: you can tell where the sephids are, and then you 470 00:24:37,840 --> 00:24:39,840 Speaker 1: can assume where the rest of the Milky Way is 471 00:24:40,119 --> 00:24:42,800 Speaker 1: because that's something we can anchor to. Yeah, hopefully the 472 00:24:43,000 --> 00:24:47,600 Speaker 1: sefond galaxy looks like the regular Milky Way galaxy, right, Like, 473 00:24:47,680 --> 00:24:50,760 Speaker 1: hopefully there's nothing weird that makes them a different shape. Yeah. Well, 474 00:24:50,800 --> 00:24:52,520 Speaker 1: if you look at some of the most recent papers 475 00:24:52,520 --> 00:24:54,959 Speaker 1: and we'll talk about these results in a minute. Mapping 476 00:24:55,000 --> 00:24:57,359 Speaker 1: the shape of the Milky Way to great detail, you 477 00:24:57,400 --> 00:25:00,399 Speaker 1: can see that we have the most concentration of sefids nearby, 478 00:25:00,480 --> 00:25:02,399 Speaker 1: because those are the ones that are easiest to see. 479 00:25:02,440 --> 00:25:04,600 Speaker 1: So we know the shape of our side of the 480 00:25:04,640 --> 00:25:06,919 Speaker 1: Milky Way much better than the other side of the 481 00:25:06,960 --> 00:25:10,400 Speaker 1: Milky Way because we haven't seen as many sephids over there. 482 00:25:10,480 --> 00:25:12,480 Speaker 1: That's all right, because we're probably in the good side 483 00:25:12,480 --> 00:25:15,119 Speaker 1: of the galaxy, right Everyone has a good side, and 484 00:25:15,119 --> 00:25:17,440 Speaker 1: if we're on this side, we're probably the better side. 485 00:25:17,600 --> 00:25:20,119 Speaker 1: If we're taking a selfie, we definitely want this profile 486 00:25:20,200 --> 00:25:23,040 Speaker 1: to show up. Yeah, yeah, And and I guess maybe 487 00:25:23,080 --> 00:25:27,440 Speaker 1: a question is why exactly are these seffids blinking so regularly? 488 00:25:27,600 --> 00:25:30,120 Speaker 1: I know it's weird, right because our son just burns, 489 00:25:30,119 --> 00:25:32,640 Speaker 1: and it burns pretty steadily, and you know, it varies 490 00:25:32,680 --> 00:25:34,840 Speaker 1: a little bit, and there's these eleven year cycles, but 491 00:25:34,880 --> 00:25:37,600 Speaker 1: it doesn't just like go up and down on time 492 00:25:37,600 --> 00:25:39,720 Speaker 1: scales of weeks and months. Imagine wou would be like 493 00:25:39,880 --> 00:25:41,600 Speaker 1: to live at a solar system like that where the 494 00:25:41,800 --> 00:25:44,800 Speaker 1: it got substantially brighter and then dimmer and brighter than dimmer. 495 00:25:45,200 --> 00:25:48,639 Speaker 1: But there's some really interesting physics going on inside the star. 496 00:25:49,080 --> 00:25:52,280 Speaker 1: It happens because these stars are mostly burning helium, and 497 00:25:52,359 --> 00:25:55,600 Speaker 1: as they get hot, the helium gets ionized, gets stripped 498 00:25:55,600 --> 00:25:59,040 Speaker 1: away from its electrons, and then it becomes opaque. So 499 00:25:59,160 --> 00:26:01,560 Speaker 1: it's still burning on the inside, but that light is 500 00:26:01,600 --> 00:26:05,720 Speaker 1: no longer leaving the star, so it absorbs its own radiation, 501 00:26:06,040 --> 00:26:09,040 Speaker 1: which makes it really hot, and then it expands, which 502 00:26:09,040 --> 00:26:12,199 Speaker 1: then cools it down, so then it's less ionized and 503 00:26:12,320 --> 00:26:15,639 Speaker 1: less transparent, and so then it sort of collapses again 504 00:26:16,240 --> 00:26:19,920 Speaker 1: until it heats up and gets more opaque and absorbs 505 00:26:19,920 --> 00:26:23,040 Speaker 1: its own radiation, which fluffs it back out again. Since 506 00:26:23,160 --> 00:26:26,720 Speaker 1: incredible cycle, and it's amazing that it's so regular. You know, 507 00:26:26,800 --> 00:26:29,280 Speaker 1: these stars go on and off, on and off on 508 00:26:29,320 --> 00:26:32,800 Speaker 1: the time scale of weeks, for millions of years. It 509 00:26:32,840 --> 00:26:36,840 Speaker 1: sounds like my diet, how much helium re meading these 510 00:26:36,920 --> 00:26:42,960 Speaker 1: days and makes me feel light? Right, Um, that's pretty cool. 511 00:26:43,040 --> 00:26:44,639 Speaker 1: So it's yeah, it's pretty regular. I wonder what it 512 00:26:44,680 --> 00:26:47,240 Speaker 1: would be like to live in a solar system like that, Like, 513 00:26:47,520 --> 00:26:49,720 Speaker 1: you know, you wouldn't just have seasons, you would also 514 00:26:49,800 --> 00:26:54,040 Speaker 1: have potentially you know, like hot sun colt sun season. Yeah, 515 00:26:54,200 --> 00:26:56,960 Speaker 1: amazingly I don't think I've ever read a science fiction 516 00:26:57,000 --> 00:27:00,280 Speaker 1: novel set on a planet orbiting a sethod. That would 517 00:27:00,320 --> 00:27:03,480 Speaker 1: be pretty fascinating. Somebody should write that one, or if 518 00:27:03,520 --> 00:27:05,720 Speaker 1: somebody has written it, please email me and let me 519 00:27:05,760 --> 00:27:07,480 Speaker 1: know because I want to read it. Yeah, and I 520 00:27:07,520 --> 00:27:10,280 Speaker 1: guess you know, we also maybe had a sense of 521 00:27:10,359 --> 00:27:14,880 Speaker 1: what our galaxy could look like by looking at other galaxies. Right, 522 00:27:14,920 --> 00:27:16,840 Speaker 1: Like we saw these mudges, and once we got a 523 00:27:16,840 --> 00:27:19,800 Speaker 1: better view of and we saw that they mostly only 524 00:27:19,840 --> 00:27:23,040 Speaker 1: fall in a couple of shapes, right, Yeah, it's pretty fascinating. 525 00:27:23,280 --> 00:27:25,359 Speaker 1: If you look at the other galaxies, you can see 526 00:27:25,480 --> 00:27:28,000 Speaker 1: a bunch of patterns, like a lot of them are 527 00:27:28,160 --> 00:27:32,080 Speaker 1: spiral galaxies like ours, where you have a heavy blob 528 00:27:32,119 --> 00:27:34,399 Speaker 1: in the middle, sort of like an egg, you know, 529 00:27:34,440 --> 00:27:37,640 Speaker 1: with a yolk, and then a few arms spiraling out 530 00:27:37,680 --> 00:27:40,520 Speaker 1: past it. And that's pretty awesome. Yeah, and what else? 531 00:27:40,560 --> 00:27:42,719 Speaker 1: You also have other kinds of galaxies, like you have 532 00:27:42,760 --> 00:27:45,840 Speaker 1: elliptical galaxies. This is the name we give galaxies that 533 00:27:46,040 --> 00:27:49,600 Speaker 1: don't really have any interesting features like these arms. And 534 00:27:49,640 --> 00:27:53,600 Speaker 1: sometimes these are big and older galaxies with older stars 535 00:27:53,600 --> 00:27:55,919 Speaker 1: in them. They're not making stars as much anymore. But 536 00:27:56,040 --> 00:27:59,920 Speaker 1: you can actually also find smaller elliptical galaxies. And then 537 00:28:00,040 --> 00:28:03,400 Speaker 1: there are the galaxies we call irregular galaxies. These are 538 00:28:03,440 --> 00:28:06,840 Speaker 1: just like smears of stars in space. They're not like 539 00:28:07,160 --> 00:28:11,400 Speaker 1: nicely organized or spinning or tight or compact in any way. 540 00:28:11,440 --> 00:28:14,320 Speaker 1: And I think these are mostly galaxies that have recently 541 00:28:14,400 --> 00:28:17,720 Speaker 1: had some sort of interaction, like two galaxies are colliding, 542 00:28:18,160 --> 00:28:19,960 Speaker 1: and in the meantime it's a bit of a mess 543 00:28:20,040 --> 00:28:23,320 Speaker 1: until gravity sort of reorganizes it back into something nice 544 00:28:23,320 --> 00:28:26,240 Speaker 1: and neat. Right to eat more fiber, maybe that might 545 00:28:26,280 --> 00:28:29,200 Speaker 1: help a little less helium in their diet. And then 546 00:28:29,200 --> 00:28:32,240 Speaker 1: there's another kind of galaxy called a dwarf galaxy. These 547 00:28:32,240 --> 00:28:34,880 Speaker 1: galaxies are much smaller. You can have galaxies of all 548 00:28:34,960 --> 00:28:37,439 Speaker 1: sorts of sizes, you know, from like three thousand to 549 00:28:38,120 --> 00:28:41,600 Speaker 1: three hundred thousand light years, but these dwarf galaxies are like, 550 00:28:41,600 --> 00:28:43,800 Speaker 1: you know, maybe a thousand light years across, contains just 551 00:28:43,880 --> 00:28:47,480 Speaker 1: about like a billion stars. And some of these are 552 00:28:47,520 --> 00:28:51,000 Speaker 1: like satellites of other galaxies, like the Milky Way has 553 00:28:51,080 --> 00:28:54,160 Speaker 1: other little galaxies orbiting it. These little dwarf galaxies sort 554 00:28:54,160 --> 00:28:56,720 Speaker 1: of going around us, right, And how did they form? 555 00:28:56,800 --> 00:28:59,960 Speaker 1: Did they form on their own? Like did they make 556 00:29:00,040 --> 00:29:03,160 Speaker 1: their own stars or did they just kind of grouped 557 00:29:03,200 --> 00:29:05,960 Speaker 1: together and got kicked out of a galaxy. Totally fascinating 558 00:29:06,000 --> 00:29:08,840 Speaker 1: topic of current research. You know, we think that some 559 00:29:08,920 --> 00:29:11,400 Speaker 1: of these formed on their own when the structure of 560 00:29:11,400 --> 00:29:13,880 Speaker 1: the universe came to be, that these pockets of dark 561 00:29:13,960 --> 00:29:17,479 Speaker 1: matter gathered together gas and dust to make galaxies. And 562 00:29:17,680 --> 00:29:19,440 Speaker 1: some of those pockets were bigger and some of them 563 00:29:19,440 --> 00:29:21,800 Speaker 1: were smaller, which is why you have a variation in 564 00:29:21,840 --> 00:29:25,600 Speaker 1: the size of galaxies. But also galaxies are turbulent, and 565 00:29:25,640 --> 00:29:28,160 Speaker 1: sometimes you have collisions, and when you have collisions, you 566 00:29:28,160 --> 00:29:30,480 Speaker 1: have like the main clump sticks together to make a 567 00:29:30,520 --> 00:29:33,480 Speaker 1: big new galaxy, but some bits get tossed off and 568 00:29:33,520 --> 00:29:35,560 Speaker 1: you end up with these little dwarf galaxies. Is sort 569 00:29:35,600 --> 00:29:39,120 Speaker 1: of like the shards of galaxies after collisions. But it's 570 00:29:39,160 --> 00:29:42,560 Speaker 1: not something we totally understand. And dwarf galaxies are a 571 00:29:42,640 --> 00:29:46,000 Speaker 1: really fascinating area of study, especially for dark matter, because 572 00:29:46,040 --> 00:29:48,000 Speaker 1: some of them have a lot of dark matter and 573 00:29:48,040 --> 00:29:50,600 Speaker 1: some of them have, like we're the almost no dark matter, 574 00:29:50,840 --> 00:29:53,200 Speaker 1: So it's something we're still trying to understand. Some of 575 00:29:53,240 --> 00:29:58,400 Speaker 1: them have dwarf matter. Probably all right, let's get into 576 00:29:59,000 --> 00:30:00,880 Speaker 1: well we actually know about the shape of the galaxy. 577 00:30:00,920 --> 00:30:03,400 Speaker 1: We talked about how we can tell what the shape is, 578 00:30:03,480 --> 00:30:07,000 Speaker 1: but let's talk about what it actually looks like. But first, 579 00:30:07,040 --> 00:30:21,720 Speaker 1: let's take another quick break. All right, the shape of 580 00:30:21,720 --> 00:30:24,760 Speaker 1: the galaxy, Daniel, Do we have a shapely milky way 581 00:30:24,920 --> 00:30:27,479 Speaker 1: or do we have a blobby note way? Does they 582 00:30:27,520 --> 00:30:29,040 Speaker 1: need to go on a diet. It definitely has a 583 00:30:29,040 --> 00:30:31,160 Speaker 1: blob in the middle, you know, like many of us 584 00:30:31,200 --> 00:30:34,240 Speaker 1: do these days. But I think it's quite a nice shape. 585 00:30:34,560 --> 00:30:36,680 Speaker 1: I like the bar in the middle and then the 586 00:30:36,720 --> 00:30:40,000 Speaker 1: spirals coming out of it. I think it's really pretty gorgeous. Well, 587 00:30:40,120 --> 00:30:42,280 Speaker 1: let's describe the milky way. What do we know about 588 00:30:42,280 --> 00:30:44,760 Speaker 1: the shape that isn't an artist rendition? What do you 589 00:30:44,760 --> 00:30:46,640 Speaker 1: mean has a bar in the middle? Yeah, so a 590 00:30:46,720 --> 00:30:49,600 Speaker 1: spiral galaxy is not just like a point in the 591 00:30:49,640 --> 00:30:53,200 Speaker 1: middle with spiral arms coming out our galaxy and like 592 00:30:53,320 --> 00:30:56,600 Speaker 1: something like two thirds of spiral galaxies have a bar. 593 00:30:56,760 --> 00:30:59,560 Speaker 1: It's like an elongated blob instead of a circle in 594 00:30:59,640 --> 00:31:02,320 Speaker 1: the middle. And then the spiral arms come out of 595 00:31:02,360 --> 00:31:05,440 Speaker 1: the edges of those bars. Wait, what what do you 596 00:31:05,440 --> 00:31:08,000 Speaker 1: mean it's a bar that's laying flat or it's like 597 00:31:08,080 --> 00:31:11,720 Speaker 1: standing up on the plane of the galaxy. No, it's 598 00:31:11,800 --> 00:31:14,160 Speaker 1: laying flat like a tassel, like a like a stick 599 00:31:14,200 --> 00:31:17,600 Speaker 1: with tassel. Yeah, exactly, it's like a stick with tassels, 600 00:31:17,640 --> 00:31:20,400 Speaker 1: and it's laying flat on the plane of the Milky Way. 601 00:31:20,440 --> 00:31:22,840 Speaker 1: And then the spiral arms started the edge of the 602 00:31:22,840 --> 00:31:26,200 Speaker 1: bar and they spin around. So we just have two arms. 603 00:31:26,240 --> 00:31:29,400 Speaker 1: We actually have multiple arms. We have a four major arms, 604 00:31:29,640 --> 00:31:32,000 Speaker 1: two really big ones and two smaller ones, and then 605 00:31:32,200 --> 00:31:35,480 Speaker 1: other little strands, so you can have multiple tassels. Out 606 00:31:35,480 --> 00:31:37,560 Speaker 1: of the edge of one side of the bar. They 607 00:31:37,600 --> 00:31:40,120 Speaker 1: go off in different directions. Yeah, they leave from sort 608 00:31:40,120 --> 00:31:42,840 Speaker 1: of like different parts of the bar, then spiral out. 609 00:31:43,200 --> 00:31:45,240 Speaker 1: Really gorgeous. You should spend some time looking at the 610 00:31:45,240 --> 00:31:48,240 Speaker 1: images of galaxies. It's beautiful. And something I only recently 611 00:31:48,320 --> 00:31:51,640 Speaker 1: understood about these spirals is that they're not just like 612 00:31:51,760 --> 00:31:54,880 Speaker 1: a bunch of stars clumped together. They're actually a shock 613 00:31:54,960 --> 00:31:59,360 Speaker 1: wave moving through the galaxy. Wait, what it's It's not 614 00:31:59,440 --> 00:32:01,840 Speaker 1: a tassel. It's more like a wave when you move 615 00:32:01,880 --> 00:32:04,200 Speaker 1: your arms through water. Yeah, there's like a shock wave 616 00:32:04,240 --> 00:32:07,480 Speaker 1: of density moving through the galaxy. And as that happens, 617 00:32:07,840 --> 00:32:11,240 Speaker 1: new stars are formed, and so it's like this new 618 00:32:11,280 --> 00:32:15,120 Speaker 1: star forming region is sort of passing through the galaxy. 619 00:32:15,160 --> 00:32:18,200 Speaker 1: I mean, the galaxy is definitely spinning, but these spiral 620 00:32:18,400 --> 00:32:22,440 Speaker 1: arms also spin relative to the galaxy. It's like one 621 00:32:22,480 --> 00:32:25,320 Speaker 1: of those toys with flashing lights, where which light is 622 00:32:25,360 --> 00:32:29,000 Speaker 1: lit up is moving and it gives the impression of motion. Right. 623 00:32:29,240 --> 00:32:31,480 Speaker 1: The spiral arms are something like that. There are these 624 00:32:31,720 --> 00:32:35,600 Speaker 1: shock waves of gas creating new stars as they move, 625 00:32:35,920 --> 00:32:39,120 Speaker 1: and so they rotate relative to the galaxy. Oh wait, 626 00:32:39,160 --> 00:32:43,040 Speaker 1: so the arms of the galaxy are not they're not 627 00:32:43,120 --> 00:32:47,360 Speaker 1: streaming stars. They're not like we were spinning, and you know, 628 00:32:47,360 --> 00:32:49,600 Speaker 1: it's sort of like the trail of a comet. Maybe 629 00:32:49,720 --> 00:32:51,920 Speaker 1: you're saying it's more it's the opposite. It's like they're 630 00:32:51,960 --> 00:32:54,280 Speaker 1: being created by something else. They're being created by this 631 00:32:54,360 --> 00:32:56,720 Speaker 1: shock wave that's passing through the galaxy. It's like the 632 00:32:56,760 --> 00:32:59,520 Speaker 1: shock wave of density that's moving through. You know, like 633 00:32:59,720 --> 00:33:02,600 Speaker 1: if you have traffic, right, somebody slams on the brake 634 00:33:02,960 --> 00:33:06,480 Speaker 1: in traffic, then this shock wave passes through the traffic, 635 00:33:06,640 --> 00:33:08,520 Speaker 1: the shock wave of density where the cars are like 636 00:33:08,600 --> 00:33:11,320 Speaker 1: all closer near to each other. And that's what's happening 637 00:33:11,320 --> 00:33:14,120 Speaker 1: in the galaxy. And that's what these arms are. And 638 00:33:14,200 --> 00:33:17,080 Speaker 1: when that happens, you get many more stars being formed, 639 00:33:17,080 --> 00:33:18,959 Speaker 1: because you know, it's not actually that easy to make 640 00:33:19,000 --> 00:33:22,040 Speaker 1: a star. You have hot gas that's all swirling around. 641 00:33:22,320 --> 00:33:24,680 Speaker 1: It's not easy for gravity to condense that down because 642 00:33:24,680 --> 00:33:27,080 Speaker 1: remember gravity is really weak. Things need to be sort 643 00:33:27,080 --> 00:33:30,160 Speaker 1: of cold and slow moving for gravity to win, and 644 00:33:30,200 --> 00:33:32,880 Speaker 1: so it needs some help. And so these shock waves 645 00:33:32,880 --> 00:33:37,280 Speaker 1: that compress the gas get things started. All right, let's continue, 646 00:33:37,360 --> 00:33:39,880 Speaker 1: And this shock wave is coming from the center of 647 00:33:39,880 --> 00:33:43,200 Speaker 1: the galaxy, like there's some some kind of event or 648 00:33:43,280 --> 00:33:45,840 Speaker 1: what created this shock wave? That's a great question. I 649 00:33:45,840 --> 00:33:48,760 Speaker 1: think it must come from the history of the galaxy formation. 650 00:33:49,120 --> 00:33:51,680 Speaker 1: A lot of these spiral galaxies are formed from the 651 00:33:51,720 --> 00:33:55,200 Speaker 1: collisions of smaller galaxies. So what you're seeing is sort 652 00:33:55,200 --> 00:33:59,360 Speaker 1: of leftover angular momentum from those collisions that's then turned 653 00:33:59,400 --> 00:34:02,040 Speaker 1: into this chocolo. Somebody spilled a lot of milk in 654 00:34:02,080 --> 00:34:06,640 Speaker 1: the Milky Way and they're still crying about it. Alright, 655 00:34:06,680 --> 00:34:08,200 Speaker 1: So then what else do we know? What else have 656 00:34:08,280 --> 00:34:10,880 Speaker 1: we found? And and I guess what's our best measurement 657 00:34:11,040 --> 00:34:13,000 Speaker 1: of the shape of the galaxy. So there's a recent 658 00:34:13,040 --> 00:34:14,920 Speaker 1: couple of papers in the last few years by this 659 00:34:15,000 --> 00:34:17,920 Speaker 1: really awesome project that's been doing a careful job of 660 00:34:18,000 --> 00:34:20,759 Speaker 1: trying to map the shape of the Milky Way. And 661 00:34:20,800 --> 00:34:23,200 Speaker 1: the project actually is a great name. It's called the 662 00:34:23,320 --> 00:34:26,160 Speaker 1: Ogol Project o g l E because hey, you know, 663 00:34:26,200 --> 00:34:28,120 Speaker 1: they're checking out the shape of the Milky Way, so 664 00:34:28,120 --> 00:34:33,840 Speaker 1: they're sort of at the stars exactly, they're creeping the 665 00:34:33,920 --> 00:34:39,000 Speaker 1: stars though. It stands for Optical Gravitational Lensing Experiment, and 666 00:34:39,120 --> 00:34:42,880 Speaker 1: it's a Polish project that's actually based in Chili, and 667 00:34:43,200 --> 00:34:46,280 Speaker 1: they can search for micro lensing like these little events, 668 00:34:46,440 --> 00:34:49,680 Speaker 1: these little gravitational lensing events where some object in our 669 00:34:49,719 --> 00:34:52,520 Speaker 1: galaxy passes in front of something in the background and 670 00:34:52,600 --> 00:34:55,719 Speaker 1: gives a little gravitational blur to it. But they can 671 00:34:55,840 --> 00:34:58,840 Speaker 1: also do a really good job of looking for sethids. 672 00:34:59,320 --> 00:35:03,400 Speaker 1: So they have the largest catalog of sephids anybody's ever collected, 673 00:35:03,600 --> 00:35:05,360 Speaker 1: and they used it to map the shape of the 674 00:35:05,400 --> 00:35:08,440 Speaker 1: Milky Way. Did they also consider calling it the lensing 675 00:35:08,480 --> 00:35:13,880 Speaker 1: Experiment with gravitational and optics, but couldn't couldn't get the copyright. 676 00:35:13,920 --> 00:35:20,960 Speaker 1: They would have been supered by Scandinavia. Can't get l copyright, no, exactly, 677 00:35:21,080 --> 00:35:22,879 Speaker 1: they have to let that go, all right, So it's 678 00:35:22,920 --> 00:35:25,920 Speaker 1: it's maybe our best view of the galaxy because they 679 00:35:26,120 --> 00:35:28,680 Speaker 1: like nobody else has looked at it with this much detail. Yeah, 680 00:35:28,680 --> 00:35:31,200 Speaker 1: they have the biggest collection. So they have twenty four 681 00:35:31,400 --> 00:35:34,799 Speaker 1: hundred sephids and they're scattered all over the galaxy, though 682 00:35:34,840 --> 00:35:37,000 Speaker 1: most of them are on our side of the galaxy 683 00:35:37,040 --> 00:35:40,160 Speaker 1: because it's easier to spot closer by sefids. And they've 684 00:35:40,280 --> 00:35:42,480 Speaker 1: learned something kind of amazing about the shape of the 685 00:35:42,480 --> 00:35:45,640 Speaker 1: Milky Way. They learned the Milky Way is not actually flat. 686 00:35:45,880 --> 00:35:48,600 Speaker 1: What it's not like a like a cooked egg. Yeah, 687 00:35:48,640 --> 00:35:50,680 Speaker 1: it's not like a cooked egg. It's got to warp 688 00:35:50,760 --> 00:35:53,600 Speaker 1: to it, so like you imagine a flat surface and 689 00:35:53,880 --> 00:35:56,120 Speaker 1: there's a blob in the middle. Well, as you move 690 00:35:56,160 --> 00:35:58,040 Speaker 1: away from the edge of the milky Way, the arms 691 00:35:58,080 --> 00:36:00,640 Speaker 1: tilt up, and on the other side the arms sort 692 00:36:00,640 --> 00:36:04,160 Speaker 1: of tilt down. So it makes like a very gentle 693 00:36:04,360 --> 00:36:06,480 Speaker 1: sort of s shape if you look at it from 694 00:36:06,480 --> 00:36:09,600 Speaker 1: the side, or like a what he said, like a tilda, 695 00:36:09,719 --> 00:36:12,480 Speaker 1: like a little squiggles from the side, the galaxy looks 696 00:36:12,480 --> 00:36:14,360 Speaker 1: like a squiggle. Yes, it's sort of cool. So I 697 00:36:14,360 --> 00:36:16,120 Speaker 1: guess you could figure that out. Yeah, if you look 698 00:36:16,280 --> 00:36:19,120 Speaker 1: close enough, you know, you would see that some stars 699 00:36:19,200 --> 00:36:21,680 Speaker 1: are higher or lower at the tips. Yeah, exactly, so 700 00:36:21,719 --> 00:36:24,799 Speaker 1: these tips are bent, we're spinning around. We have these 701 00:36:24,840 --> 00:36:27,000 Speaker 1: cool structure, We have the bar, we have the spirals. 702 00:36:27,120 --> 00:36:29,960 Speaker 1: But then we also have this twist, like this literal 703 00:36:30,040 --> 00:36:32,600 Speaker 1: twist in the story about the shape of the Milky Way, 704 00:36:32,840 --> 00:36:35,319 Speaker 1: this thing we've been trying to understand for hundreds of 705 00:36:35,400 --> 00:36:38,680 Speaker 1: years now has this really interesting wrinkle to it. And 706 00:36:38,760 --> 00:36:41,320 Speaker 1: that shape. Is it rotating with the galaxy or is 707 00:36:41,360 --> 00:36:44,720 Speaker 1: the galaxy kind of like undulating as well as it's spinning. 708 00:36:44,960 --> 00:36:49,319 Speaker 1: It's fascinating, it's actually undulating. Like the galaxy takes two 709 00:36:49,440 --> 00:36:52,319 Speaker 1: hundred twenty million years for a star to go all 710 00:36:52,360 --> 00:36:55,040 Speaker 1: the way around. That's like the length of a galactic year. 711 00:36:55,440 --> 00:36:57,920 Speaker 1: Our son will be back where it is today in 712 00:36:58,000 --> 00:37:02,640 Speaker 1: two hundred twenty million years. But this twist takes like 713 00:37:02,760 --> 00:37:06,200 Speaker 1: six or seven hundred million years to rotate. It's moving 714 00:37:06,360 --> 00:37:09,719 Speaker 1: slower than the actual stars. Wow. So like if you 715 00:37:09,760 --> 00:37:12,439 Speaker 1: spit up a movie of the galaxy, you would see 716 00:37:12,440 --> 00:37:14,680 Speaker 1: it like rippling kind of yes, exactly, And that's what 717 00:37:14,719 --> 00:37:17,400 Speaker 1: I'm talking about that you're seemed as like really long 718 00:37:17,520 --> 00:37:20,520 Speaker 1: term physics, sort of a frozen moment of it in 719 00:37:20,600 --> 00:37:24,040 Speaker 1: time like the galaxy is not just a blob sitting there. 720 00:37:24,280 --> 00:37:28,040 Speaker 1: It's undulating, it's rippling, it's twisting, it's torking, right, But 721 00:37:28,120 --> 00:37:31,440 Speaker 1: we're seeing just a moment of it. These incredible galactic 722 00:37:31,520 --> 00:37:34,840 Speaker 1: forces that operate over like millions and billions of years. 723 00:37:35,280 --> 00:37:37,799 Speaker 1: We can spot it with just these images. That's when 724 00:37:37,800 --> 00:37:42,080 Speaker 1: I find really beautiful about these dynamic astronomical images. Did 725 00:37:42,080 --> 00:37:48,279 Speaker 1: you say torking or torking, say the galaxy twirking? I 726 00:37:48,320 --> 00:37:50,960 Speaker 1: think actually that's what's going on, is that it's twerking 727 00:37:50,960 --> 00:37:54,480 Speaker 1: with some other nearby galaxy. We need the galaxy kid 728 00:37:54,520 --> 00:37:58,160 Speaker 1: party so much. I know, who knew the galaxy was 729 00:37:58,200 --> 00:38:00,520 Speaker 1: not safe for work? Yeah? Alright, so but why is 730 00:38:00,560 --> 00:38:04,960 Speaker 1: it tworking or warping or undulating after all this time? 731 00:38:04,960 --> 00:38:07,040 Speaker 1: Wouldn't it just settle into a nice disc kind of 732 00:38:07,080 --> 00:38:09,200 Speaker 1: like the Solar system? Yeah, you would think so. And 733 00:38:09,239 --> 00:38:11,880 Speaker 1: if this was an ancient effect, then it would settle 734 00:38:11,920 --> 00:38:14,640 Speaker 1: into a fixed shape and it would just rotate in 735 00:38:14,680 --> 00:38:17,600 Speaker 1: that shape. But we think that probably what's going on 736 00:38:17,800 --> 00:38:19,759 Speaker 1: is that this is something more recent, something in the 737 00:38:19,800 --> 00:38:23,759 Speaker 1: last fifty million years, not something ancient that's then been 738 00:38:23,840 --> 00:38:27,040 Speaker 1: ironed out. It's something which is still happening, and so 739 00:38:27,120 --> 00:38:30,880 Speaker 1: we think it's probably not something like intergalactic magnetic fields 740 00:38:31,080 --> 00:38:34,080 Speaker 1: or the shape of dark matter, which are more static 741 00:38:34,120 --> 00:38:36,680 Speaker 1: and not changing as much. We think probably what's going 742 00:38:36,719 --> 00:38:39,960 Speaker 1: on is that it's interacting with some other galaxy. Really 743 00:38:40,239 --> 00:38:45,120 Speaker 1: what that the ripple could be our reaction to another galaxy. Yeah, 744 00:38:45,160 --> 00:38:48,799 Speaker 1: Like there could be some dwarf galaxy that's orbiting the 745 00:38:48,840 --> 00:38:52,160 Speaker 1: Milky Way or that's in the process of being absorbed 746 00:38:52,280 --> 00:38:54,959 Speaker 1: by the Milky Way. Think about what happens when two 747 00:38:55,040 --> 00:38:58,280 Speaker 1: objects like galaxies absorb each other. They don't just smash 748 00:38:58,360 --> 00:39:01,760 Speaker 1: together and form one thing. They passed through each other first, 749 00:39:02,040 --> 00:39:04,600 Speaker 1: slow down, and then come back. They sort of slashed 750 00:39:04,680 --> 00:39:08,200 Speaker 1: back and forth a few times before they coalesced into 751 00:39:08,239 --> 00:39:10,560 Speaker 1: one object. And if you looked at that, just like 752 00:39:10,719 --> 00:39:14,400 Speaker 1: one snapshot, one moment in time, you might see this 753 00:39:14,520 --> 00:39:17,120 Speaker 1: kind of thing that the objects start to distort each 754 00:39:17,160 --> 00:39:20,479 Speaker 1: other before they actually coalesce. So this could be some 755 00:39:20,880 --> 00:39:24,240 Speaker 1: dwarf galaxy nearby, you know, like fifty or a hundred 756 00:39:24,239 --> 00:39:27,319 Speaker 1: thousand light years away, that has already crashed through the 757 00:39:27,360 --> 00:39:29,840 Speaker 1: disc of the galaxy once, creating this kind of ripple, 758 00:39:30,080 --> 00:39:32,400 Speaker 1: and it's slowing down turning around to come back for 759 00:39:32,440 --> 00:39:36,400 Speaker 1: another pass. It's pretty fascinating. Yeah, it seems like the 760 00:39:36,480 --> 00:39:39,680 Speaker 1: galaxy has a much more interesting shape than maybe we 761 00:39:39,760 --> 00:39:42,080 Speaker 1: thought before. Yeah, and that's because it's part of a 762 00:39:42,120 --> 00:39:45,000 Speaker 1: huge dynamical system. These galaxies are all in a dance 763 00:39:45,080 --> 00:39:48,080 Speaker 1: with each other. You know, they're separated by millions of 764 00:39:48,160 --> 00:39:50,440 Speaker 1: light years, but they still tug on each other. And 765 00:39:50,520 --> 00:39:53,520 Speaker 1: remember that our galaxy is not just sprinkled in space 766 00:39:53,560 --> 00:39:56,120 Speaker 1: with other galaxies. There's a bunch of other ones nearby. 767 00:39:56,239 --> 00:39:59,759 Speaker 1: We're all orbiting a common central point. And so each 768 00:39:59,800 --> 00:40:02,480 Speaker 1: g EAXI is like a particle of gas in this 769 00:40:02,600 --> 00:40:05,160 Speaker 1: larger system, you know, and each one has like spin 770 00:40:05,239 --> 00:40:07,520 Speaker 1: and bounce and it's all story and it's you know, 771 00:40:07,600 --> 00:40:09,520 Speaker 1: hit this other one and bounced off this wall and 772 00:40:09,560 --> 00:40:12,680 Speaker 1: crazy stuff. So each one has a real dynamical history. 773 00:40:12,719 --> 00:40:15,000 Speaker 1: They're not just like hanging out in space doing nothing, 774 00:40:15,040 --> 00:40:17,520 Speaker 1: and we are just a tiny little spec in one 775 00:40:17,600 --> 00:40:20,440 Speaker 1: corner of it, right, Yeah, Like we're just a tiny 776 00:40:20,480 --> 00:40:23,759 Speaker 1: speck in a tiny speck in a tiny speck in 777 00:40:23,840 --> 00:40:26,120 Speaker 1: one of its arms, Yeah, exactly. And we're not at 778 00:40:26,160 --> 00:40:28,120 Speaker 1: the center of our milky Way, and we're not out 779 00:40:28,160 --> 00:40:30,120 Speaker 1: at the edge that we are in the center when 780 00:40:30,120 --> 00:40:31,600 Speaker 1: it comes to us sort of the up and down, 781 00:40:31,680 --> 00:40:34,799 Speaker 1: Like we're pretty close to the galactic plane when it 782 00:40:34,840 --> 00:40:37,719 Speaker 1: comes to being off for on the galactic plane, but 783 00:40:37,760 --> 00:40:39,920 Speaker 1: we're not that close to the center or midtwerk or 784 00:40:40,040 --> 00:40:42,400 Speaker 1: mid twerk. Yeah, but it's good that we're not that 785 00:40:42,440 --> 00:40:45,279 Speaker 1: close to the center because there's a huge amount of 786 00:40:45,400 --> 00:40:48,120 Speaker 1: radiation from stuff going on in the center of the galaxy. 787 00:40:48,400 --> 00:40:50,160 Speaker 1: And it's also probably because they were not too far 788 00:40:50,280 --> 00:40:53,239 Speaker 1: out from the center because there are fewer metals out 789 00:40:53,320 --> 00:40:56,160 Speaker 1: there to be harder to have awesome things like steel 790 00:40:56,320 --> 00:40:58,120 Speaker 1: and aluminum and all that kind of stuff we need 791 00:40:58,120 --> 00:41:01,160 Speaker 1: to build our civilization. So we're in a pretty good spot. Yeah, 792 00:41:01,239 --> 00:41:03,160 Speaker 1: you don't want to be too far away from a party, 793 00:41:03,200 --> 00:41:04,680 Speaker 1: but you don't want to be too close to the 794 00:41:04,680 --> 00:41:08,560 Speaker 1: party either, that's right. You want to go to work 795 00:41:08,600 --> 00:41:13,080 Speaker 1: and just the right spot, just like Goldilocks. All right. Well, 796 00:41:13,200 --> 00:41:16,080 Speaker 1: it's overall really amazing that we can get a sense 797 00:41:16,120 --> 00:41:17,680 Speaker 1: of what the shape of the galaxy. I mean, think 798 00:41:17,719 --> 00:41:20,120 Speaker 1: about what a huge problem it is to know what 799 00:41:20,200 --> 00:41:23,399 Speaker 1: the shape of the ocean you're in or the land 800 00:41:23,440 --> 00:41:26,640 Speaker 1: you're on. The fact that we can you know understand 801 00:41:26,640 --> 00:41:30,160 Speaker 1: the universe that much and have these amazing telescopes and 802 00:41:30,160 --> 00:41:33,640 Speaker 1: techniques and engineering and technology. Is pretty incredible that we 803 00:41:33,640 --> 00:41:37,040 Speaker 1: can get a sense of our home in our place 804 00:41:37,080 --> 00:41:39,960 Speaker 1: in the galaxy. Yeah, it really is selfies on a 805 00:41:40,040 --> 00:41:43,600 Speaker 1: cosmic scale. You know, Before we had cameras, people would 806 00:41:43,600 --> 00:41:46,360 Speaker 1: like look in lakes to see their reflection and wonder like, 807 00:41:46,440 --> 00:41:48,640 Speaker 1: what do I look? Likely they knew what all their 808 00:41:48,680 --> 00:41:51,160 Speaker 1: family and friends and everybody around them look like, But 809 00:41:51,200 --> 00:41:53,440 Speaker 1: it's harder to get a picture of your own body, 810 00:41:53,520 --> 00:41:56,240 Speaker 1: your own face. And in the same way, we wonder 811 00:41:56,320 --> 00:41:59,320 Speaker 1: like what does our galaxy look like? It's weirdly more 812 00:41:59,400 --> 00:42:02,799 Speaker 1: challenging to understand the shape of our own galaxy then 813 00:42:02,880 --> 00:42:06,080 Speaker 1: our neighboring galaxy for just the same reasons. So it's 814 00:42:06,120 --> 00:42:08,239 Speaker 1: cool that we've developed all these techniques to get a 815 00:42:08,280 --> 00:42:11,120 Speaker 1: map for like our own home. Yeah, although I think 816 00:42:11,120 --> 00:42:14,000 Speaker 1: I guess technically you should call an ugly maybe not 817 00:42:14,120 --> 00:42:19,279 Speaker 1: a selfie, that's an ugly word for it. Yeah, all right, Well, 818 00:42:19,320 --> 00:42:21,480 Speaker 1: the next time you get to see some stars out 819 00:42:21,480 --> 00:42:23,720 Speaker 1: there in the sky, or maybe even get a glimpse 820 00:42:23,760 --> 00:42:26,960 Speaker 1: of the Milky Way, think about how much we know 821 00:42:27,000 --> 00:42:30,200 Speaker 1: about it and how we know about it and what 822 00:42:30,280 --> 00:42:35,160 Speaker 1: an incredible and maybe beautiful structure it is. That's right. 823 00:42:35,200 --> 00:42:37,880 Speaker 1: And any time you find yourself contemplating the universe and 824 00:42:37,920 --> 00:42:41,080 Speaker 1: there's something about it you just don't quite understand or 825 00:42:41,160 --> 00:42:44,279 Speaker 1: are wondering about, please write to us, suggested as a 826 00:42:44,280 --> 00:42:47,520 Speaker 1: podcast or just ask us a question. We love our 827 00:42:47,560 --> 00:42:51,000 Speaker 1: listener emails, so send them on to Questions at Daniel 828 00:42:51,040 --> 00:42:53,839 Speaker 1: and Jorhey dot com. We hope you enjoyed that, and hey, 829 00:42:54,120 --> 00:42:56,680 Speaker 1: do us a favorite this week? Maybe tell your friends 830 00:42:56,680 --> 00:43:00,320 Speaker 1: about the podcast or follow us on Instagram or Twitter 831 00:43:00,640 --> 00:43:02,719 Speaker 1: so you can learn more about what we're up to. 832 00:43:03,280 --> 00:43:13,280 Speaker 1: Thanks for joining us. Let's see you next time. Thanks 833 00:43:13,280 --> 00:43:15,880 Speaker 1: for listening, and remember that Daniel and Jorge explained the 834 00:43:16,000 --> 00:43:19,080 Speaker 1: Universe is a production of I Heart Radio. For more 835 00:43:19,200 --> 00:43:22,200 Speaker 1: podcast from my Heart Radio, visit the I Heart Radio 836 00:43:22,239 --> 00:43:26,280 Speaker 1: Apple Apple Podcasts, or wherever you listen to your favorite shows.