1 00:00:01,560 --> 00:00:04,760 Speaker 1: Welcome to Stuff from the Science Lab from how stuff 2 00:00:04,760 --> 00:00:16,200 Speaker 1: works dot com. Hey guys, and welcome to the podcast. 3 00:00:16,239 --> 00:00:19,320 Speaker 1: This is Alice Madam, science how stuff works dot com. 4 00:00:19,360 --> 00:00:21,400 Speaker 1: And this is Robert Lamb, science writer at how stuff 5 00:00:21,400 --> 00:00:24,439 Speaker 1: works dot com. Today we're doing the third podcast in 6 00:00:24,520 --> 00:00:29,080 Speaker 1: our very first recurring series, and that series has been 7 00:00:29,120 --> 00:00:32,120 Speaker 1: looking at how different celestial bodies get their start. Today 8 00:00:32,120 --> 00:00:34,760 Speaker 1: we're talking about galaxies. If I had to listen to 9 00:00:34,760 --> 00:00:37,440 Speaker 1: the series, I would start with galaxies, then go to stars, 10 00:00:37,479 --> 00:00:40,000 Speaker 1: and then listen to planets, just for heads up if 11 00:00:40,040 --> 00:00:42,000 Speaker 1: you haven't heard any of them. Okay, but not because 12 00:00:42,000 --> 00:00:46,400 Speaker 1: of preference, right, because no, just because because one thing 13 00:00:46,400 --> 00:00:48,839 Speaker 1: that occurred to me when I was actually writing our 14 00:00:48,960 --> 00:00:51,560 Speaker 1: article about that galaxy formation is that this one, I 15 00:00:51,560 --> 00:00:55,400 Speaker 1: think is often overlooked because like the formation of the universe, 16 00:00:55,880 --> 00:00:58,760 Speaker 1: like that, like the Big Bang, like that's so huge 17 00:00:58,840 --> 00:01:01,520 Speaker 1: and mind boggling that you instantly think of that, and 18 00:01:01,560 --> 00:01:04,640 Speaker 1: then things like the formation of a planet or the 19 00:01:04,640 --> 00:01:06,640 Speaker 1: solar system that's a lot closer to home and you 20 00:01:06,640 --> 00:01:08,360 Speaker 1: can relate to that a little better. But a galaxy 21 00:01:08,400 --> 00:01:11,679 Speaker 1: that's just kind of somewhere in between. It's not Yeah, 22 00:01:11,959 --> 00:01:14,840 Speaker 1: I mean, it's enormous. It's on such an enormous scale, 23 00:01:14,880 --> 00:01:19,720 Speaker 1: but not on such a just mind boggling cosmic scale 24 00:01:19,959 --> 00:01:22,320 Speaker 1: that people set around and I think, ponderate unless you're 25 00:01:22,440 --> 00:01:26,399 Speaker 1: you know, like actually a cosmologist or after physicist. So 26 00:01:26,440 --> 00:01:28,480 Speaker 1: we have to back up to the Big Bang. But 27 00:01:28,480 --> 00:01:31,360 Speaker 1: we're not going to get into the Big Bang. Um. 28 00:01:31,480 --> 00:01:36,360 Speaker 1: So it is a galaxy. A galaxy, Well, it is 29 00:01:36,400 --> 00:01:40,240 Speaker 1: the largest structure in the universe, and it binds billions 30 00:01:40,319 --> 00:01:43,800 Speaker 1: or even trillions of stars together in a big gravitational yoke. 31 00:01:44,680 --> 00:01:46,959 Speaker 1: What else is in galaxies besides stars? Well, you've got 32 00:01:46,959 --> 00:01:52,600 Speaker 1: planets yep, yeah, cats, dog, Well that's on the smaller scale. 33 00:01:52,640 --> 00:01:57,360 Speaker 1: But no, you've got cosmic dust, vast clouds of gas, um, 34 00:01:57,400 --> 00:02:01,200 Speaker 1: you know, comets, like every thing really if you can 35 00:02:01,280 --> 00:02:04,600 Speaker 1: name it, it's in the galaxy, including dark matter, yes, 36 00:02:04,680 --> 00:02:09,160 Speaker 1: dark matter, dark energy, all that good stuff. So let's 37 00:02:09,200 --> 00:02:13,320 Speaker 1: rewind roughly fourteen billion years ago, two win galaxies got 38 00:02:13,320 --> 00:02:16,120 Speaker 1: their start. Yeah, back to the Big Bang, which is 39 00:02:16,120 --> 00:02:19,200 Speaker 1: our best theory about how all this came about. And 40 00:02:19,360 --> 00:02:21,640 Speaker 1: I like to think of and this is a this 41 00:02:21,680 --> 00:02:24,600 Speaker 1: is a very basic analogy, but I like to think 42 00:02:24,639 --> 00:02:26,639 Speaker 1: that this way. Imagine you have a map of the 43 00:02:26,760 --> 00:02:30,680 Speaker 1: universe right spread out on a table. Yes, now, no, now, 44 00:02:30,720 --> 00:02:33,440 Speaker 1: imagine the entire map like wadded up into a single 45 00:02:33,480 --> 00:02:37,600 Speaker 1: ball of paper. But a ball of paper like just 46 00:02:37,720 --> 00:02:41,120 Speaker 1: microscopic and size, you know, just ridiculously small. Yeah. I've 47 00:02:41,120 --> 00:02:45,280 Speaker 1: come across a different a few different estimations of how 48 00:02:46,000 --> 00:02:50,000 Speaker 1: big or how small via that singularity was. Some people 49 00:02:50,040 --> 00:02:51,640 Speaker 1: say it's about the size of a dime. Other people 50 00:02:51,680 --> 00:02:54,080 Speaker 1: say it's smaller than an electron. Yeah, yeah, you see it. 51 00:02:54,160 --> 00:02:59,200 Speaker 1: See size estimation is bearing. But whatever the exact size, 52 00:02:59,480 --> 00:03:03,440 Speaker 1: a whole lot, like everything, the entire universe crunched down 53 00:03:03,440 --> 00:03:06,600 Speaker 1: to one unimaginably small because whether we're talking about the 54 00:03:06,600 --> 00:03:08,400 Speaker 1: size of a quarter or the size of a basketball 55 00:03:08,520 --> 00:03:11,040 Speaker 1: or the size of an atom. Um that's a lot 56 00:03:11,080 --> 00:03:15,560 Speaker 1: of universe packed into one god stopper. And then it 57 00:03:15,960 --> 00:03:20,160 Speaker 1: then it expands and yeah, and you have hot matter, 58 00:03:20,280 --> 00:03:22,800 Speaker 1: it ends up cooling. But but nothing has there's not 59 00:03:22,840 --> 00:03:25,840 Speaker 1: really any structure. It's not like wham, now we have 60 00:03:25,880 --> 00:03:28,480 Speaker 1: you know, galaxies and planets, etcetera. You just have a 61 00:03:28,480 --> 00:03:32,280 Speaker 1: lot of like it's like raw uncooked galaxy. No not, 62 00:03:32,400 --> 00:03:34,800 Speaker 1: I mean raw uncooked universe out there. Yeah, you have 63 00:03:34,800 --> 00:03:38,320 Speaker 1: the ingredients. You just have a lot of gas, a 64 00:03:38,320 --> 00:03:43,120 Speaker 1: lot of dust just floating out there. So how those 65 00:03:43,240 --> 00:03:47,040 Speaker 1: ingredients evolve in somewhere than a hundred billion galaxies. Well, 66 00:03:47,080 --> 00:03:50,680 Speaker 1: there are two bodies of theories according to NASA about 67 00:03:50,680 --> 00:03:55,160 Speaker 1: how this came about, all right. There are bottom up 68 00:03:55,200 --> 00:04:00,960 Speaker 1: theories and they're top down theories, and this sort of 69 00:04:00,960 --> 00:04:03,080 Speaker 1: sounds like what they are. Yeah, you know, it's it's 70 00:04:03,120 --> 00:04:06,280 Speaker 1: kind of like in a bottom up theory, the gas, 71 00:04:06,440 --> 00:04:09,520 Speaker 1: all this gas and dust collapses and compresses into a 72 00:04:09,600 --> 00:04:13,600 Speaker 1: clump about the size of a million sons. And that's 73 00:04:13,800 --> 00:04:18,040 Speaker 1: that's starting small for something that's gonna become, you know, galaxies. 74 00:04:18,360 --> 00:04:21,720 Speaker 1: All right. These clumps then merge to build galaxies. All right. 75 00:04:21,839 --> 00:04:26,240 Speaker 1: Again bottom up, and as we touched onto some previous podcasts, 76 00:04:26,480 --> 00:04:29,640 Speaker 1: this is acretion. This is the process of little particles 77 00:04:29,640 --> 00:04:33,200 Speaker 1: coming together forming slightly larger particles which then have a 78 00:04:33,240 --> 00:04:36,080 Speaker 1: gravitational pull on other particles. It's like a snowball going 79 00:04:36,080 --> 00:04:38,240 Speaker 1: down a hill. Right. If you're listening to these podcasts, 80 00:04:38,240 --> 00:04:41,279 Speaker 1: there's definitely a theme of acretion running through all of them. Yeah. 81 00:04:41,880 --> 00:04:44,160 Speaker 1: So yeah, this one is just that the gas collapse 82 00:04:44,360 --> 00:04:49,840 Speaker 1: into enormous but cosmically small clumps which then end up 83 00:04:49,839 --> 00:04:54,080 Speaker 1: forming larger clumps which become galaxies. And then you have 84 00:04:54,160 --> 00:04:57,120 Speaker 1: your top down theories, which of course start big. And 85 00:04:57,160 --> 00:04:58,839 Speaker 1: the school of thought is going to argue that the 86 00:04:58,880 --> 00:05:01,960 Speaker 1: resulting clumps were each of us of multiple galaxies, and 87 00:05:02,000 --> 00:05:03,840 Speaker 1: then the size got too big to manage, and they 88 00:05:03,839 --> 00:05:07,480 Speaker 1: broke down into our individual galaxy, like the Milky Way galaxy. 89 00:05:07,640 --> 00:05:11,680 Speaker 1: And if you follow this train of thought, then you 90 00:05:11,680 --> 00:05:15,160 Speaker 1: get an understanding of why galaxies occur in clusters, but 91 00:05:15,240 --> 00:05:17,680 Speaker 1: either way bottom up, top down. The resulting clumps then 92 00:05:17,720 --> 00:05:21,200 Speaker 1: collapsed into proto galaxies, which consisted of dark matter and 93 00:05:21,279 --> 00:05:25,680 Speaker 1: hydrogen gas. Yeah, and then the hydrogen then falls to 94 00:05:25,760 --> 00:05:27,960 Speaker 1: the center of the proto galaxy, wanted the dark matter 95 00:05:28,000 --> 00:05:32,400 Speaker 1: remains as an outer halo surrounding everything. You know. When 96 00:05:32,400 --> 00:05:35,599 Speaker 1: we're researching this podcast, it came across another interesting theory, 97 00:05:35,920 --> 00:05:40,640 Speaker 1: that of hierarchical formation, in which merging of established galaxies 98 00:05:40,640 --> 00:05:44,000 Speaker 1: occurs too, And so the story on it was this. 99 00:05:44,320 --> 00:05:47,320 Speaker 1: Researchers from University of Switzerland saw some merging galaxies in 100 00:05:47,360 --> 00:05:51,120 Speaker 1: a group dubed s g oh Dash one two, which 101 00:05:51,120 --> 00:05:55,080 Speaker 1: is a very sexy name for those galaxies. Right, and 102 00:05:55,320 --> 00:05:58,040 Speaker 1: roughly four billion light years away, and they reported their 103 00:05:58,080 --> 00:06:00,479 Speaker 1: findings in the August two thousand eight issue of the 104 00:06:00,600 --> 00:06:06,480 Speaker 1: Astrophysical Journal Letters. Have you read that, lady, Robert so Um, 105 00:06:06,520 --> 00:06:09,080 Speaker 1: they were saying that smaller galaxies were destined for one 106 00:06:09,080 --> 00:06:11,920 Speaker 1: another courtesy of the mutual gravitational attraction, and then they 107 00:06:11,960 --> 00:06:15,400 Speaker 1: formed these massive galaxies. Okay, so that was that was 108 00:06:15,440 --> 00:06:18,320 Speaker 1: their take on it, and their theory also stipulated that 109 00:06:18,360 --> 00:06:22,120 Speaker 1: star formation would primarily occur when galaxies were small, but 110 00:06:22,400 --> 00:06:25,640 Speaker 1: they would gather all their mass during the mergers. But 111 00:06:25,720 --> 00:06:28,720 Speaker 1: we'll get to star formation in the second. So astronomers 112 00:06:28,760 --> 00:06:34,840 Speaker 1: recognized to basic shapes for galaxies. There's elliptical and then 113 00:06:34,880 --> 00:06:37,960 Speaker 1: their spiral and we're spiral galaxies, but we're technically a 114 00:06:38,000 --> 00:06:40,880 Speaker 1: spiral bar galaxy. Yeah right, a lot of them are 115 00:06:40,880 --> 00:06:45,440 Speaker 1: actually yeah, well the spiral galaxies are essentially we're spiral galaxy. 116 00:06:45,600 --> 00:06:47,880 Speaker 1: And you also have you disorganized galaxies, which are kind 117 00:06:47,880 --> 00:06:52,800 Speaker 1: of my favorite. Which, um, if you think about two 118 00:06:52,880 --> 00:06:56,760 Speaker 1: galaxies merging, um, maybe when they first merged, they they're 119 00:06:57,040 --> 00:06:59,360 Speaker 1: disorganized and then they sort themselves out into their neat 120 00:06:59,400 --> 00:07:02,080 Speaker 1: spiral shape for their elliptical shape, but who knows, they're 121 00:07:02,080 --> 00:07:04,640 Speaker 1: not sure of that. And then there's a third type 122 00:07:04,680 --> 00:07:07,800 Speaker 1: of galaxy, UM, the disorganized galaxy, which you have to 123 00:07:07,880 --> 00:07:10,520 Speaker 1: kind of identify with this kind of galaxy, right, um, 124 00:07:10,920 --> 00:07:14,000 Speaker 1: that disorganized but no, no, no no, that was not a 125 00:07:14,000 --> 00:07:20,400 Speaker 1: personal rabbert. Although are you disorganized? No, just I'm organized, 126 00:07:20,440 --> 00:07:22,840 Speaker 1: but in a disorganized fashion at times. Depends on what 127 00:07:22,880 --> 00:07:24,760 Speaker 1: I'm doing. Well, they say, the people who have very 128 00:07:24,840 --> 00:07:26,960 Speaker 1: organized deaths have too much time in their hands, right yeah. 129 00:07:26,960 --> 00:07:29,240 Speaker 1: And then some people don't don't decorate their offices at all, 130 00:07:29,320 --> 00:07:31,480 Speaker 1: or their cubicles. That's just I don't know if that's 131 00:07:31,640 --> 00:07:33,760 Speaker 1: not being if that's being really organized, or that's just 132 00:07:33,800 --> 00:07:37,920 Speaker 1: being lame. I know somebody at work who had decorated 133 00:07:38,040 --> 00:07:40,960 Speaker 1: their cubicle and then took it down in protest when 134 00:07:40,960 --> 00:07:42,720 Speaker 1: she had a bad day one day, and she never 135 00:07:42,720 --> 00:07:45,440 Speaker 1: put it back up. I don't think it's an odd 136 00:07:45,480 --> 00:07:51,040 Speaker 1: form of protests. It didn't convey anything to me. Attachment detachment. 137 00:07:51,320 --> 00:07:55,400 Speaker 1: I think say these UM, so you have your your spirals, 138 00:07:55,400 --> 00:07:58,240 Speaker 1: you have your ellipticals, and then UM, at least initially, 139 00:07:58,240 --> 00:08:01,080 Speaker 1: emerged galaxies might not like these two main shapes. They 140 00:08:01,120 --> 00:08:06,360 Speaker 1: might be disorganized, but eventually astronomers believe that the merge 141 00:08:06,400 --> 00:08:11,400 Speaker 1: galaxies result in an elliptical galaxy. As such, our Milky 142 00:08:11,400 --> 00:08:14,000 Speaker 1: Way has probably never emerged with another galaxy, because again 143 00:08:14,000 --> 00:08:18,040 Speaker 1: it's that's hard spiral shape. But the massive elliptical galaxies 144 00:08:18,040 --> 00:08:20,800 Speaker 1: found at the center of galaxy clusters are probably the 145 00:08:20,840 --> 00:08:23,840 Speaker 1: result of some serious cosmic mashups. Yeah, it's just it's 146 00:08:23,840 --> 00:08:27,560 Speaker 1: almost it's kind of like accretion on a huge scale, 147 00:08:27,640 --> 00:08:30,880 Speaker 1: with just galaxies running into each other, just becoming this big, 148 00:08:31,000 --> 00:08:35,920 Speaker 1: enormous thing. But the interesting thing that I was reading 149 00:08:35,920 --> 00:08:39,400 Speaker 1: about is just because two galaxies passed close by, they 150 00:08:39,440 --> 00:08:41,120 Speaker 1: don't have to merge, they don't have to make this 151 00:08:41,200 --> 00:08:44,679 Speaker 1: one big galactic family. Rapidly moving ones I read can 152 00:08:44,720 --> 00:08:48,320 Speaker 1: pass through one another, sort of like ghosts almost, but 153 00:08:48,400 --> 00:08:50,360 Speaker 1: the slower moving ones seemed to be likely to get 154 00:08:50,360 --> 00:08:53,600 Speaker 1: all up in each other's business and merge. Something to 155 00:08:53,640 --> 00:08:58,120 Speaker 1: keep in mind when we went eventually merged with Andromeda. Right, indeed, 156 00:08:59,480 --> 00:09:04,400 Speaker 1: so let's about star formation and the elliptical and spiral galaxies. Okay, 157 00:09:04,440 --> 00:09:07,000 Speaker 1: how does that figure in? All? Right? Well, stars develop 158 00:09:07,080 --> 00:09:09,440 Speaker 1: inside a proto galaxy when the cloud, when the clouds 159 00:09:09,440 --> 00:09:12,240 Speaker 1: of gas mix and collide, so of all the stars 160 00:09:12,240 --> 00:09:14,760 Speaker 1: in a proto galaxy form at once, and the mature 161 00:09:14,840 --> 00:09:18,440 Speaker 1: galaxy essentially retains the roundest shape of the proto galaxy 162 00:09:18,520 --> 00:09:23,640 Speaker 1: and becomes an elliptical galaxy. Spiral galaxies, however, occur when 163 00:09:23,679 --> 00:09:26,520 Speaker 1: the stars inside the proto galaxy or as at different intervals, 164 00:09:26,920 --> 00:09:28,839 Speaker 1: so you know, they're not popping up all at once, 165 00:09:28,880 --> 00:09:31,800 Speaker 1: They're happening at different times, and the gas between the 166 00:09:31,800 --> 00:09:35,520 Speaker 1: developing stars continues to collapse, and the resulting gravitational differences 167 00:09:35,600 --> 00:09:38,360 Speaker 1: manhandle the proto galaxy stars, the dust, and the gas. 168 00:09:39,800 --> 00:09:42,000 Speaker 1: What do you know? This motion starts to force everything 169 00:09:42,040 --> 00:09:46,040 Speaker 1: into a rotating disk, and additional differences in gravity result 170 00:09:46,080 --> 00:09:48,840 Speaker 1: in the spiral arms. It's kind of like when I 171 00:09:48,880 --> 00:09:50,400 Speaker 1: was trying to make sense of this, I thought of 172 00:09:50,400 --> 00:09:53,080 Speaker 1: it in terms of, like imagine like with an elliptical galaxy, 173 00:09:53,120 --> 00:09:56,040 Speaker 1: Like imagine a town where everybody's the same age, you know, 174 00:09:56,720 --> 00:09:59,280 Speaker 1: only like everybody's like thirty five, so you only have 175 00:09:59,360 --> 00:10:01,280 Speaker 1: the kind of places thirty five year olds hang out, 176 00:10:01,600 --> 00:10:05,920 Speaker 1: like no, you know, no place where like teenagers roll 177 00:10:06,120 --> 00:10:08,679 Speaker 1: or where it's one of those over fifty communities. That's 178 00:10:08,720 --> 00:10:10,640 Speaker 1: what it is. Yeah, Yeah, that kind of thing whereas 179 00:10:10,679 --> 00:10:13,440 Speaker 1: elliptical has would like an elliptical galaxy is like a 180 00:10:13,440 --> 00:10:16,480 Speaker 1: town where you have guys of all ages with his 181 00:10:16,520 --> 00:10:20,760 Speaker 1: diversity and conflict spinning everything around, so much more interesting 182 00:10:20,760 --> 00:10:22,959 Speaker 1: place to live if you're into that. Yeah, so that's 183 00:10:23,000 --> 00:10:25,520 Speaker 1: my convoluted analogy of the day. Did you know that 184 00:10:25,600 --> 00:10:29,680 Speaker 1: the Milky Way galaxy is rotating and will complete a 185 00:10:29,720 --> 00:10:35,640 Speaker 1: revolution in two fifty million years, like a galactic year? 186 00:10:36,320 --> 00:10:39,360 Speaker 1: That would be okay, Yeah, it's a lot longer than 187 00:10:39,360 --> 00:10:41,120 Speaker 1: one of those restaurants that rotates at the top of 188 00:10:41,120 --> 00:10:45,360 Speaker 1: the hotel will market on the calendar. Put them in 189 00:10:45,400 --> 00:10:52,400 Speaker 1: Google calendar alert. Galactic year just finished. Well, said Robert. 190 00:10:52,679 --> 00:10:55,280 Speaker 1: So that was kind of a light intro to galaxy formation. 191 00:10:55,320 --> 00:10:57,719 Speaker 1: If you guys want to hear more about the mechanics 192 00:10:57,760 --> 00:11:00,480 Speaker 1: of galaxy formation or get deeper into the topic, send 193 00:11:00,520 --> 00:11:02,280 Speaker 1: us an email at science Stuff at hows to first 194 00:11:02,320 --> 00:11:04,520 Speaker 1: dot com and we'll see what we can do. For instance, 195 00:11:04,679 --> 00:11:06,439 Speaker 1: like bottom up theories, there are a number of bottom 196 00:11:06,480 --> 00:11:08,240 Speaker 1: up theories. There are a number of top down theories, 197 00:11:08,480 --> 00:11:10,920 Speaker 1: but they're a number of steps. Yeah, and but these 198 00:11:10,920 --> 00:11:13,480 Speaker 1: are the basics, and obviously there's a lot of formation 199 00:11:13,520 --> 00:11:17,840 Speaker 1: that continues um, you know at lower levels within the galaxy, 200 00:11:17,920 --> 00:11:21,839 Speaker 1: which we've touched down on in uh in other podcasts. Yeah, 201 00:11:21,960 --> 00:11:24,200 Speaker 1: as always, you can take galaxies into the search part 202 00:11:24,360 --> 00:11:26,920 Speaker 1: on how Stuff Works homepage and see what good stuff 203 00:11:26,920 --> 00:11:30,400 Speaker 1: that brings up. They're gonna see how galaxies work. Maybe 204 00:11:30,400 --> 00:11:32,280 Speaker 1: whether space has a shape? This is a good one. 205 00:11:33,440 --> 00:11:35,240 Speaker 1: Is there a hole in space? That's another one that 206 00:11:35,280 --> 00:11:37,960 Speaker 1: we have, Yeah, or the big bank very written by Strickland. 207 00:11:37,960 --> 00:11:40,040 Speaker 1: But I think you did a good job. Hey, and 208 00:11:40,080 --> 00:11:42,439 Speaker 1: we also have a Facebook and a Twitter account now, 209 00:11:42,559 --> 00:11:46,920 Speaker 1: so um you can check those out. Just to search 210 00:11:47,000 --> 00:11:50,000 Speaker 1: for stuff in the science lab or lab stuff on 211 00:11:50,080 --> 00:11:52,840 Speaker 1: Twitter on Twitter or Facebook and then lead you right 212 00:11:52,920 --> 00:11:57,280 Speaker 1: to us, and uh we update that thing pretty pretty regularly. 213 00:11:58,880 --> 00:12:02,520 Speaker 1: Come see what science the topics we're thinking about this week. 214 00:12:03,400 --> 00:12:05,400 Speaker 1: So that's all the galactic goodness we have for you 215 00:12:05,440 --> 00:12:15,840 Speaker 1: guys today. Thanks for listening. For more on this and 216 00:12:15,880 --> 00:12:19,240 Speaker 1: thousands of other topics. Is it how stuff works dot com? 217 00:12:19,520 --> 00:12:22,280 Speaker 1: Want more how stuff works? Check out our blogs on 218 00:12:22,360 --> 00:12:24,120 Speaker 1: the house stuff works dot com home page