1 00:00:08,480 --> 00:00:13,440 Speaker 1: Hail. Hey, have you ever seen two stars collide? Well, 2 00:00:13,560 --> 00:00:16,880 Speaker 1: I live near Hollywood, so it does happen sometimes. What 3 00:00:16,920 --> 00:00:19,720 Speaker 1: do you mean, you know, like Brad Pitt and Angelina Julie, 4 00:00:19,720 --> 00:00:22,760 Speaker 1: they're like binary star system. I get it. And when 5 00:00:22,800 --> 00:00:26,360 Speaker 1: they collided, it sent out paparazzi waves or something. Yeah, 6 00:00:26,360 --> 00:00:29,160 Speaker 1: it sends out ripples in the fabric of the entertainment 7 00:00:29,200 --> 00:00:33,479 Speaker 1: space time. Well, I hope that's somewhere. Alien physicists have 8 00:00:33,520 --> 00:00:36,000 Speaker 1: built a device to measure those ripples and are wondering 9 00:00:36,320 --> 00:00:40,199 Speaker 1: what it is they're looking at. Probably two attractive human beings, hope, 10 00:00:40,200 --> 00:00:57,360 Speaker 1: only they're not thinking how delicious they look. Ye Hi 11 00:00:57,440 --> 00:01:00,520 Speaker 1: am Or Hammock cartoonists and the creator of pH D comment, Hi, 12 00:01:00,600 --> 00:01:03,160 Speaker 1: I'm Daniel. I'm a particle physicist, and I live in 13 00:01:03,200 --> 00:01:07,039 Speaker 1: southern California. But I've never accidentally bumped into a celebrity. 14 00:01:07,720 --> 00:01:10,360 Speaker 1: How about on purpose? Have you bumped into one on purpose? No? 15 00:01:10,480 --> 00:01:13,360 Speaker 1: Their bodyguards keep me away. It's so frustrating. Really, you 16 00:01:13,400 --> 00:01:15,920 Speaker 1: live down here and you've never had a celebrity sighting. 17 00:01:16,280 --> 00:01:18,559 Speaker 1: I've seen them from afar, but always imagine I would 18 00:01:18,560 --> 00:01:21,120 Speaker 1: bump into one at the grocery store or something m 19 00:01:21,560 --> 00:01:23,360 Speaker 1: I see. Well, sort of you're sort of becoming a 20 00:01:23,400 --> 00:01:26,200 Speaker 1: star yourself, Daniel, And at least in the Physics Podcast 21 00:01:26,280 --> 00:01:29,040 Speaker 1: universe whatever, I can walk around you see Irvine and 22 00:01:29,040 --> 00:01:31,959 Speaker 1: people think I'm just some homeless person or a professor, 23 00:01:31,959 --> 00:01:34,920 Speaker 1: one of those you need to confuse sometimes. How would 24 00:01:34,959 --> 00:01:36,920 Speaker 1: you have you had any good celebrity sightings and all 25 00:01:37,000 --> 00:01:40,479 Speaker 1: your years in Hollywood? Sure? Yeah, yeah, I've I've had severally. Yeah, 26 00:01:40,840 --> 00:01:43,360 Speaker 1: sometimes you or you can't get away from them sometimes. 27 00:01:44,200 --> 00:01:46,480 Speaker 1: But welcome to a podcast. Daniel and Jorge explain the 28 00:01:46,560 --> 00:01:49,600 Speaker 1: university production of I Heart Radio, in which we collide 29 00:01:49,600 --> 00:01:53,400 Speaker 1: your brain and the universe. We take all the incredible, 30 00:01:53,480 --> 00:01:56,280 Speaker 1: all the amazing, all the bonkers, all the wild stuff 31 00:01:56,280 --> 00:01:58,840 Speaker 1: that's out there, and we squish it all into your 32 00:01:58,880 --> 00:02:02,400 Speaker 1: head because we think that the entire universe should be 33 00:02:02,520 --> 00:02:06,480 Speaker 1: understandable and should be explainable to everyone. Yeah, because it 34 00:02:06,800 --> 00:02:09,160 Speaker 1: is sort of a wild universe. It's a lot happening 35 00:02:09,240 --> 00:02:12,960 Speaker 1: in it. There's obviously stars burning bright out there, and 36 00:02:13,080 --> 00:02:16,760 Speaker 1: planets orbiting them and asteroids flying around. But sometimes we 37 00:02:16,840 --> 00:02:21,040 Speaker 1: get some pretty interesting events happening. That's right, while you 38 00:02:21,080 --> 00:02:23,120 Speaker 1: look out into the sky and it seems sort of 39 00:02:23,160 --> 00:02:25,520 Speaker 1: like static. It seems like, hey, it's just sort of 40 00:02:25,560 --> 00:02:28,400 Speaker 1: hanging out, it's not really doing anything. If you watch 41 00:02:28,480 --> 00:02:32,000 Speaker 1: the universe in fast forward, it would seem like a crazy, 42 00:02:32,120 --> 00:02:35,120 Speaker 1: chaotic place. It would seem like a drink that somebody 43 00:02:35,200 --> 00:02:37,400 Speaker 1: is shaking really really fast. It would seem like the 44 00:02:37,440 --> 00:02:40,160 Speaker 1: mosh pit at a crazy concert. What's the music that 45 00:02:40,200 --> 00:02:43,280 Speaker 1: the universe is dancing to? Is it like punk rock 46 00:02:43,360 --> 00:02:46,800 Speaker 1: but it's super slow motion? Exactly? The universe is a 47 00:02:46,840 --> 00:02:50,000 Speaker 1: super slow mo punk rock concert. But it is interesting 48 00:02:50,040 --> 00:02:51,880 Speaker 1: to think about all the things that could be happening 49 00:02:51,880 --> 00:02:54,600 Speaker 1: out there, and all of the near misses and all 50 00:02:54,639 --> 00:02:56,560 Speaker 1: of the things sort of flying by each other, and 51 00:02:56,639 --> 00:03:00,160 Speaker 1: sometimes things sort of inevitably collide out there in the 52 00:03:00,240 --> 00:03:03,160 Speaker 1: universe because there's a lot of space out there in space, 53 00:03:03,400 --> 00:03:06,840 Speaker 1: but also a big universe, So eventually everything's going to 54 00:03:06,880 --> 00:03:09,480 Speaker 1: happen at some point exactly. And we're not unfamiliar with 55 00:03:09,520 --> 00:03:12,560 Speaker 1: the idea of collisions. After all, we know that sometimes 56 00:03:12,680 --> 00:03:15,960 Speaker 1: asteroids hit planets, right. We see craters all over the 57 00:03:16,000 --> 00:03:18,960 Speaker 1: surfaces of everything in the Solar System. We even see 58 00:03:19,000 --> 00:03:22,040 Speaker 1: comets smashing the planets, like Shoemaker Levy did a few 59 00:03:22,040 --> 00:03:25,399 Speaker 1: decades ago. But what about bigger collisions? Is it possible 60 00:03:25,440 --> 00:03:28,640 Speaker 1: for even larger things to smash into each other? Yeah? 61 00:03:28,720 --> 00:03:31,360 Speaker 1: Isn't the prevailing theory about our moon is that it 62 00:03:31,440 --> 00:03:34,720 Speaker 1: came from a big collision of the Earth with an asteroid, Right, 63 00:03:34,760 --> 00:03:37,520 Speaker 1: That's how the moon was born. Yeah, maybe not even 64 00:03:37,560 --> 00:03:41,680 Speaker 1: an asteroid. Maybe two proto planets collided merged in the 65 00:03:41,680 --> 00:03:44,200 Speaker 1: Earth on the Moon are like weird mixtures of those 66 00:03:44,240 --> 00:03:48,720 Speaker 1: two planets. It's an awesome titanic collision. Yeah, but you're 67 00:03:48,720 --> 00:03:53,160 Speaker 1: thinking even bigger than planets or proto planets colliding. You're 68 00:03:53,160 --> 00:03:57,480 Speaker 1: thinking maybe stars colliding. That's right, Why not always think bigger? Right? 69 00:03:57,760 --> 00:03:59,800 Speaker 1: These collisions are boring. Now when we go to the 70 00:03:59,800 --> 00:04:02,080 Speaker 1: next level, it's like fast and furious. They gotta get 71 00:04:02,120 --> 00:04:05,840 Speaker 1: even crazier. Yeah, what happens when vin diesel collides with 72 00:04:05,920 --> 00:04:09,960 Speaker 1: the rock. Everyone knows about that. Exactly what happens is 73 00:04:09,960 --> 00:04:12,680 Speaker 1: they each get their own movie franchise because they handworked. 74 00:04:13,040 --> 00:04:16,640 Speaker 1: That's the only way that it can go on. So yeah, 75 00:04:16,640 --> 00:04:18,800 Speaker 1: so that was an elastic collision because they both seem 76 00:04:18,839 --> 00:04:21,479 Speaker 1: to have survived it with their careers intact. But is 77 00:04:21,520 --> 00:04:24,960 Speaker 1: it always so clean? What happens when bigger things smash 78 00:04:25,000 --> 00:04:27,440 Speaker 1: into each other. Does that ever happen? Has it happened 79 00:04:27,440 --> 00:04:29,560 Speaker 1: to our son? These are the kind of questions that 80 00:04:29,720 --> 00:04:32,080 Speaker 1: keep me up at night. Yeah, so today we'll be 81 00:04:32,120 --> 00:04:35,320 Speaker 1: looking into some stellar events, and in particular, we'll be 82 00:04:35,360 --> 00:04:44,400 Speaker 1: asking the question what happens when stars collide? And are 83 00:04:44,440 --> 00:04:50,120 Speaker 1: their children as good looking as they are? Usually? Not? Right? Oh, 84 00:04:50,200 --> 00:04:53,560 Speaker 1: are you throwing shade on the children of stars right now? 85 00:04:53,600 --> 00:04:56,320 Speaker 1: Showley Jolie or whatever her name is. I thought you 86 00:04:56,320 --> 00:05:00,599 Speaker 1: were still talking about stars, like real stars. Put it 87 00:05:00,640 --> 00:05:04,600 Speaker 1: on me, like stellar objects. I think all stellar objects 88 00:05:04,600 --> 00:05:09,000 Speaker 1: are beautiful, even the ones that might inevitably come for us. 89 00:05:09,240 --> 00:05:11,400 Speaker 1: But yeah, it is pretty interesting. I guess that there 90 00:05:11,400 --> 00:05:13,400 Speaker 1: are so many stars out there in the galaxy and 91 00:05:13,440 --> 00:05:16,280 Speaker 1: the universe that eventually some of them might run into 92 00:05:16,279 --> 00:05:18,440 Speaker 1: each other, right, they might crash into each other. It 93 00:05:18,440 --> 00:05:20,440 Speaker 1: turns out to be quite interesting. In some parts of 94 00:05:20,440 --> 00:05:23,880 Speaker 1: the universe, stellar collisions are quite common, and in other 95 00:05:23,920 --> 00:05:26,800 Speaker 1: places they're very rare. So, as usually, we were wondering 96 00:05:26,839 --> 00:05:30,000 Speaker 1: how many people out there had thought about these stellar collisions, 97 00:05:30,000 --> 00:05:33,280 Speaker 1: these stars colliding, and what would happened, And so Daniel 98 00:05:33,279 --> 00:05:35,719 Speaker 1: went out there to ask people on the Internet. What 99 00:05:35,880 --> 00:05:39,080 Speaker 1: do you think happens when stars collide? That's right and 100 00:05:39,120 --> 00:05:42,560 Speaker 1: as usual. I'm grateful to our Internet volunteers for answering 101 00:05:42,640 --> 00:05:45,280 Speaker 1: random physics questions. If it sounds fun to you to 102 00:05:45,360 --> 00:05:48,320 Speaker 1: get four random physics questions and your inbox that you 103 00:05:48,360 --> 00:05:51,520 Speaker 1: have to answer without any preparation, please just write us 104 00:05:51,520 --> 00:05:54,600 Speaker 1: an email two questions at Daniel and Jorge dot com. 105 00:05:54,760 --> 00:05:56,360 Speaker 1: So think about it for a second. What do you think? 106 00:05:56,400 --> 00:05:58,240 Speaker 1: What do you see in your head when you imagine 107 00:05:58,279 --> 00:06:02,000 Speaker 1: two stars colliding. Here's what people have to say, Well, 108 00:06:02,040 --> 00:06:08,880 Speaker 1: I don't think they usually collide because um having this 109 00:06:09,200 --> 00:06:13,920 Speaker 1: um fusion inside them and all the energy coming out 110 00:06:14,000 --> 00:06:20,800 Speaker 1: of the sun. I think actually it's not usually for 111 00:06:20,960 --> 00:06:26,040 Speaker 1: the stars to collide. Yes, and very often, because there's 112 00:06:26,080 --> 00:06:28,960 Speaker 1: so many stars out in the universe. It seems like 113 00:06:29,000 --> 00:06:32,880 Speaker 1: a trick question, like everyone would say, yeah, they collide, 114 00:06:32,960 --> 00:06:36,039 Speaker 1: that's how they form mergers and stuff. But it's probably 115 00:06:36,720 --> 00:06:40,920 Speaker 1: really unlikely that two stars would hit each other smack 116 00:06:41,000 --> 00:06:44,760 Speaker 1: on on the first pass. They would pass close to 117 00:06:44,800 --> 00:06:49,479 Speaker 1: each other and lock into orbit around each other. Maybe 118 00:06:49,480 --> 00:06:51,599 Speaker 1: once they're locked in orbit around each other, either that's 119 00:06:51,600 --> 00:06:55,000 Speaker 1: stable or one of them is way bigger and it 120 00:06:55,240 --> 00:06:57,680 Speaker 1: sucks the matter out of the other one. Well, I 121 00:06:57,839 --> 00:07:01,200 Speaker 1: definitely think they do. And some terms, whole galaxies can 122 00:07:01,240 --> 00:07:06,440 Speaker 1: actually collide post each other's past and just became one. Um. 123 00:07:06,480 --> 00:07:08,599 Speaker 1: I could imagine that it would probably happen with a 124 00:07:08,680 --> 00:07:11,680 Speaker 1: huge explosion or just I don't know, depending on their 125 00:07:11,760 --> 00:07:15,440 Speaker 1: mass and like what gases are burning in them. And 126 00:07:15,560 --> 00:07:18,400 Speaker 1: for example, if there's like a Jewel star star system 127 00:07:18,680 --> 00:07:21,200 Speaker 1: and they just don't know, like really close to each 128 00:07:21,240 --> 00:07:24,720 Speaker 1: other and orbiting each other or just being really close 129 00:07:24,760 --> 00:07:27,720 Speaker 1: to each other, they can also exchange matter maybe just 130 00:07:27,800 --> 00:07:30,960 Speaker 1: get closer and closer to each other by gravitational pool 131 00:07:31,040 --> 00:07:33,480 Speaker 1: and at one point they can just get so close 132 00:07:33,560 --> 00:07:37,600 Speaker 1: that they actually collide. They do. They circle around one 133 00:07:37,640 --> 00:07:41,320 Speaker 1: another and then eventually collide into one another or fall 134 00:07:41,400 --> 00:07:43,800 Speaker 1: into one another. I think yes and no. I think 135 00:07:43,800 --> 00:07:45,720 Speaker 1: it is possible for things to crash into each other. 136 00:07:45,760 --> 00:07:48,600 Speaker 1: Things with master fall into each other, just like how 137 00:07:48,640 --> 00:07:51,840 Speaker 1: they discover gravity waves too, black holes crash into each other. 138 00:07:52,320 --> 00:07:55,320 Speaker 1: But also I think space is very spacey and for 139 00:07:55,520 --> 00:07:57,560 Speaker 1: things to death spiral into each other has to be 140 00:07:57,640 --> 00:08:02,120 Speaker 1: special uh circumstances. Because I think when objects roach each 141 00:08:02,160 --> 00:08:04,440 Speaker 1: other around each other, like say stars are rotating around 142 00:08:04,440 --> 00:08:06,960 Speaker 1: each other. I think they it's possible to have stable orbits, 143 00:08:06,960 --> 00:08:10,560 Speaker 1: so there has to be some special math where if 144 00:08:10,600 --> 00:08:14,040 Speaker 1: they fall over a certain criteria, then then yes, objects 145 00:08:14,080 --> 00:08:16,920 Speaker 1: in space like stars with mass will crash into each other. 146 00:08:17,480 --> 00:08:22,240 Speaker 1: I would say, very very rarely nowadays. Maybe it was 147 00:08:22,480 --> 00:08:26,440 Speaker 1: more common in the very early universe when the what 148 00:08:26,600 --> 00:08:30,040 Speaker 1: is it third generation of stars was firstborn. Maybe those 149 00:08:30,080 --> 00:08:33,720 Speaker 1: collided from time to time, but nowadays it's very rare. 150 00:08:34,080 --> 00:08:37,679 Speaker 1: All right. I'm seeing where it's like huge explosion crashes. 151 00:08:38,880 --> 00:08:42,280 Speaker 1: Some pretty exciting times here, also some very technical answers, 152 00:08:42,320 --> 00:08:45,200 Speaker 1: like space is very spacey. It's a good point. It 153 00:08:45,280 --> 00:08:48,080 Speaker 1: is pretty spacey. There's it's a roomy too. There's a 154 00:08:48,080 --> 00:08:50,520 Speaker 1: lot of room in the space of rooms. That's right. 155 00:08:50,559 --> 00:08:54,480 Speaker 1: It's very minimally appointed in the universe. It's not overcrowded. Yeah. Well, 156 00:08:54,480 --> 00:08:56,320 Speaker 1: I like the person who thought it was a trick question, 157 00:08:56,400 --> 00:09:00,679 Speaker 1: like maybe stars never collided, but is that possible? Maybe 158 00:09:00,720 --> 00:09:04,160 Speaker 1: they just bump into each other at the supermarket by 159 00:09:04,320 --> 00:09:07,120 Speaker 1: quote accident unquote. Hey, I was reaching for that box 160 00:09:07,120 --> 00:09:09,320 Speaker 1: of cookies exactly, and up in a tug of war 161 00:09:09,400 --> 00:09:11,320 Speaker 1: with Brad Pitt over a box of cookies. That's my 162 00:09:11,360 --> 00:09:14,040 Speaker 1: Southern California dream. There you go. I'm guessing Brad Pitt 163 00:09:14,160 --> 00:09:18,720 Speaker 1: will will win no offense. He's pretty strong. But yeah, 164 00:09:18,760 --> 00:09:21,320 Speaker 1: it seems like some people didn't think they would actually collide, 165 00:09:21,320 --> 00:09:24,000 Speaker 1: and some people thought that it happens, I mean, binary 166 00:09:24,040 --> 00:09:26,880 Speaker 1: star systems. There's a wide range of answers here, and 167 00:09:26,920 --> 00:09:29,280 Speaker 1: that maybe this is an interesting one. People thought that 168 00:09:29,400 --> 00:09:33,080 Speaker 1: maybe it happens more often in the early universe than 169 00:09:33,120 --> 00:09:36,080 Speaker 1: in the older universe. Yeah, really fascinating stuff. I like 170 00:09:36,160 --> 00:09:38,240 Speaker 1: the people are using their physics brains to think about 171 00:09:38,320 --> 00:09:41,080 Speaker 1: what would make this happen. Yeah, because I guess in 172 00:09:41,160 --> 00:09:44,120 Speaker 1: the early universe things were more crowded, right, technically, Well, 173 00:09:44,160 --> 00:09:46,160 Speaker 1: we'll get into it. It's quite interesting. You know, in 174 00:09:46,200 --> 00:09:48,840 Speaker 1: the early universe the stars had just formed and so 175 00:09:48,960 --> 00:09:52,360 Speaker 1: galaxies hadn't formed yet, so in some sense, things were 176 00:09:52,440 --> 00:09:55,240 Speaker 1: less dense. All right, well, let's jump into it, Daniel. 177 00:09:55,559 --> 00:09:59,240 Speaker 1: What happens when stars collide? How common are these star collisions? 178 00:09:59,280 --> 00:10:02,720 Speaker 1: It depends on lot on where you are, because star 179 00:10:02,880 --> 00:10:05,960 Speaker 1: densities vary a lot from place to place. Like in 180 00:10:06,000 --> 00:10:09,000 Speaker 1: the center of the galaxy, things are much denser. The 181 00:10:09,120 --> 00:10:13,320 Speaker 1: distances between stars are much smaller than they are out 182 00:10:13,360 --> 00:10:16,160 Speaker 1: here where we are where like twenty thousand light years 183 00:10:16,200 --> 00:10:18,280 Speaker 1: from the center of the galaxy, sort of like out 184 00:10:18,320 --> 00:10:21,200 Speaker 1: in the suburbs. Out here, there's like three or four 185 00:10:21,360 --> 00:10:24,920 Speaker 1: light years between stars, and so it's much less likely 186 00:10:25,200 --> 00:10:28,280 Speaker 1: for stars to collide. Like the closest star to us 187 00:10:28,400 --> 00:10:32,200 Speaker 1: is Proximus Centauri, just under four light years away. In 188 00:10:32,320 --> 00:10:35,240 Speaker 1: terms of the width of our Sun, that's like one 189 00:10:35,360 --> 00:10:38,600 Speaker 1: hundred million sun width. Like if you try to fill 190 00:10:38,679 --> 00:10:40,680 Speaker 1: up the space between our Sun and the next star, 191 00:10:40,920 --> 00:10:43,520 Speaker 1: you'd have to stack it with a hundred million copies 192 00:10:43,640 --> 00:10:45,600 Speaker 1: of our Sun. That gives you a sense for like 193 00:10:45,679 --> 00:10:49,079 Speaker 1: how far apart stars are in our neighborhood. M M, 194 00:10:49,360 --> 00:10:51,560 Speaker 1: that's interesting. What about closer to the center of the 195 00:10:51,559 --> 00:10:54,679 Speaker 1: galaxy or stars more crunched together, Like what are the 196 00:10:54,760 --> 00:10:57,480 Speaker 1: relative distances there? So in the center of the galaxy 197 00:10:57,480 --> 00:10:59,959 Speaker 1: it can get much much denser in the stars average 198 00:11:00,080 --> 00:11:02,480 Speaker 1: less than a light year apart, but it grows very 199 00:11:02,600 --> 00:11:05,440 Speaker 1: very quickly as you get closer to that black hole, 200 00:11:05,559 --> 00:11:07,760 Speaker 1: things get very very dense. And it's not just the 201 00:11:07,760 --> 00:11:10,560 Speaker 1: center of the galaxy where things are denser. Our galaxy 202 00:11:10,600 --> 00:11:14,520 Speaker 1: has these things called globular clusters, which are collections of 203 00:11:14,600 --> 00:11:17,360 Speaker 1: stars we think formed all at the same time or 204 00:11:17,559 --> 00:11:20,560 Speaker 1: might even be like many dwarf for galaxies that got 205 00:11:20,600 --> 00:11:23,360 Speaker 1: eaten by the Milky Way. But these are much much 206 00:11:23,400 --> 00:11:25,920 Speaker 1: denser than the rest of the galaxy. So you're saying 207 00:11:25,960 --> 00:11:28,520 Speaker 1: that even in the outer parts of the galaxy there 208 00:11:28,600 --> 00:11:31,160 Speaker 1: might be sort of like dense clusters where there could 209 00:11:31,160 --> 00:11:33,680 Speaker 1: be a lot of stars running into each other. Yeah, 210 00:11:33,679 --> 00:11:36,480 Speaker 1: these globular clusters, they're fascinating. We did a whole podcast 211 00:11:36,480 --> 00:11:39,000 Speaker 1: episode about them last year. Some of them are sort 212 00:11:39,040 --> 00:11:41,200 Speaker 1: of embedded in the Milky Way, and some of them 213 00:11:41,200 --> 00:11:43,920 Speaker 1: are sort of like in close orbit around the Milky Way, 214 00:11:43,920 --> 00:11:46,000 Speaker 1: but people consider it all to be part of the 215 00:11:46,040 --> 00:11:48,719 Speaker 1: Milky Way. So in the center of the galaxy and 216 00:11:48,840 --> 00:11:53,040 Speaker 1: in globular clusters, there are better conditions for having collisions. 217 00:11:53,040 --> 00:11:55,440 Speaker 1: Like out here where we are, for the Sun to 218 00:11:55,520 --> 00:11:59,040 Speaker 1: get into a collision is very very unlikely. Somebody actually 219 00:11:59,120 --> 00:12:02,120 Speaker 1: did a calculation and they estimate that the Sun should 220 00:12:02,120 --> 00:12:06,559 Speaker 1: collide with another star every ten to the twenty eight years. 221 00:12:07,040 --> 00:12:09,240 Speaker 1: Like that's a hard number to think about. Just remember 222 00:12:09,280 --> 00:12:12,600 Speaker 1: that the universe is ten to the ten years old, 223 00:12:12,800 --> 00:12:14,960 Speaker 1: so it would take a lot lot longer than the 224 00:12:15,000 --> 00:12:17,640 Speaker 1: age of the universe, so far before we expect the 225 00:12:17,720 --> 00:12:21,320 Speaker 1: Sun to collide with anything interesting, So it seems like 226 00:12:21,480 --> 00:12:23,840 Speaker 1: pretty unlikely, although I wonder if it's like, you know, 227 00:12:24,120 --> 00:12:25,800 Speaker 1: like in in the center of a downtown, there's a 228 00:12:25,840 --> 00:12:28,760 Speaker 1: lot more traffic, but people are going slower maybe, but 229 00:12:28,880 --> 00:12:31,480 Speaker 1: out in the submers where you have these empty highways 230 00:12:31,520 --> 00:12:33,640 Speaker 1: that maybe people are going faster, And so wonder of 231 00:12:33,720 --> 00:12:36,800 Speaker 1: that increases the likelihood of a crash. Things are actually 232 00:12:36,800 --> 00:12:39,520 Speaker 1: moving really rapidly in the center of the galaxy because 233 00:12:39,559 --> 00:12:42,280 Speaker 1: things are closer to the source of gravity. Right, there's 234 00:12:42,280 --> 00:12:44,920 Speaker 1: a huge black hole there, and when a star, for example, 235 00:12:45,000 --> 00:12:47,200 Speaker 1: swings around the back of that black hole, it picks 236 00:12:47,280 --> 00:12:49,560 Speaker 1: up a lot of speed. These stars can get up 237 00:12:49,559 --> 00:12:51,480 Speaker 1: to like half of the speed of light when the 238 00:12:51,520 --> 00:12:53,840 Speaker 1: whizz around the back of that black hole. So things 239 00:12:53,840 --> 00:12:56,520 Speaker 1: are moving pretty rapidly in the center of the galaxy. 240 00:12:56,679 --> 00:12:59,880 Speaker 1: They estimate that in globular clusters there's a stellar coll 241 00:13:00,040 --> 00:13:03,719 Speaker 1: vision every ten thousand years. Well it's a lot, right, 242 00:13:03,920 --> 00:13:06,040 Speaker 1: I mean, in terms of the age of the universe, 243 00:13:06,120 --> 00:13:08,760 Speaker 1: that's like crash every other day. That's a lot of 244 00:13:08,800 --> 00:13:12,680 Speaker 1: collisions exactly. And if you estimate how many globular clusters 245 00:13:12,720 --> 00:13:15,400 Speaker 1: there are in all of the galaxies out there. The 246 00:13:15,480 --> 00:13:18,200 Speaker 1: current estimate is about a trillion or so, you know, 247 00:13:18,440 --> 00:13:20,400 Speaker 1: give or take to a factor of ten. But if 248 00:13:20,400 --> 00:13:23,200 Speaker 1: you assume that there are a trillion globular clusters in 249 00:13:23,240 --> 00:13:26,360 Speaker 1: the observable universe, then that estimate tells you that there 250 00:13:26,400 --> 00:13:30,320 Speaker 1: are a thousand pairs of stars colliding at every moment, 251 00:13:30,559 --> 00:13:33,880 Speaker 1: Like right now, a thousand stars are colliding with a 252 00:13:33,920 --> 00:13:38,160 Speaker 1: thousand other stars. Wow, that's amazing to think about, for sure. Yeah, 253 00:13:38,480 --> 00:13:41,880 Speaker 1: like right now, boom or a thousand booms stars colliding 254 00:13:43,400 --> 00:13:46,319 Speaker 1: a thousand booms exactly. And these are not stars that 255 00:13:46,360 --> 00:13:49,640 Speaker 1: are colliding like in neighborhoods similar to our son. These 256 00:13:49,640 --> 00:13:51,679 Speaker 1: are stars colliding in the center of the galaxy or 257 00:13:51,720 --> 00:13:55,240 Speaker 1: again in these globular clusters that these pockets of density 258 00:13:55,360 --> 00:13:58,199 Speaker 1: elsewhere in the galaxy. But we're not near any one 259 00:13:58,200 --> 00:14:00,400 Speaker 1: of these globular clusters, right, I mean, we have them 260 00:14:00,400 --> 00:14:02,480 Speaker 1: in the Milky Way, but are we near one. We 261 00:14:02,520 --> 00:14:05,440 Speaker 1: aren't near any globular clusters, not near enough to be 262 00:14:05,520 --> 00:14:08,040 Speaker 1: worried about it or like to be sucked in or anything. 263 00:14:08,320 --> 00:14:11,080 Speaker 1: So these collisions are happening in other places, But globular 264 00:14:11,080 --> 00:14:14,440 Speaker 1: clusters are really fascinating scientifically and help us probe really 265 00:14:14,440 --> 00:14:17,600 Speaker 1: interesting questions about the formations of stars. And there's still 266 00:14:17,640 --> 00:14:21,320 Speaker 1: a lot of things that we don't understand about globular clusters. Yeah, 267 00:14:21,360 --> 00:14:24,120 Speaker 1: they're sort of almost sort of where people call them 268 00:14:24,160 --> 00:14:26,080 Speaker 1: like the cradle of stars, right like sort of, or 269 00:14:26,240 --> 00:14:28,640 Speaker 1: nursery star nurseries they call them, right, Yeah, And these 270 00:14:28,680 --> 00:14:31,160 Speaker 1: things are typically really really old, like they think they 271 00:14:31,240 --> 00:14:34,720 Speaker 1: might mostly be population two stars. So these things were 272 00:14:34,720 --> 00:14:37,680 Speaker 1: formed billions and billions of years ago in the second 273 00:14:37,720 --> 00:14:40,520 Speaker 1: generation of stars, after the first ones blew up, the 274 00:14:40,560 --> 00:14:43,800 Speaker 1: second generation formed, and these sort of low metalisity. They 275 00:14:43,800 --> 00:14:46,480 Speaker 1: don't have as many heavy elements in them as our 276 00:14:46,560 --> 00:14:50,200 Speaker 1: stars do because the universe hadn't made as much heavy metals, 277 00:14:50,440 --> 00:14:52,360 Speaker 1: but they were all born about the same time. And 278 00:14:52,400 --> 00:14:54,760 Speaker 1: so when you look at the globular cluster, you're seeing 279 00:14:54,760 --> 00:14:57,760 Speaker 1: a lot of really old stars, or at least we thought. 280 00:14:58,280 --> 00:15:00,960 Speaker 1: And they found a bunch of stars inside these globular 281 00:15:01,000 --> 00:15:04,400 Speaker 1: clusters that look sort of unusually young, like they're really 282 00:15:04,440 --> 00:15:08,040 Speaker 1: really blue stars, which means that glow really really brightly 283 00:15:08,440 --> 00:15:11,320 Speaker 1: and really bright glowing stars tend to not live very long, 284 00:15:11,360 --> 00:15:13,760 Speaker 1: they like burn out really fast. So there are these 285 00:15:13,760 --> 00:15:16,840 Speaker 1: stars in these globular clusters that look really blue, look 286 00:15:16,880 --> 00:15:19,200 Speaker 1: really young when the rest of the globular cluster is 287 00:15:19,240 --> 00:15:21,760 Speaker 1: really old. So they imagine that what might be happening 288 00:15:21,840 --> 00:15:23,480 Speaker 1: is that you could be getting like a bunch of 289 00:15:23,480 --> 00:15:26,040 Speaker 1: stars that collide. They're like on their way at the 290 00:15:26,160 --> 00:15:27,840 Speaker 1: end of their life, and then they collide to form 291 00:15:27,880 --> 00:15:30,880 Speaker 1: a new huge star which then burns brightly. So these 292 00:15:30,880 --> 00:15:34,400 Speaker 1: are called blue stragglers. They are currently a mystery in astronomy, 293 00:15:34,400 --> 00:15:37,840 Speaker 1: but that's one possible explanation for them. Interesting. So they're 294 00:15:37,880 --> 00:15:40,640 Speaker 1: old and so maybe they're not as heavy metals, so 295 00:15:40,640 --> 00:15:44,080 Speaker 1: maybe they're listening to music under parties. It's sort of 296 00:15:44,120 --> 00:15:46,520 Speaker 1: like two stars at the end of their career decide, hey, 297 00:15:46,680 --> 00:15:49,720 Speaker 1: let's have kids and they can carry on burning brightly 298 00:15:49,760 --> 00:15:52,400 Speaker 1: and earning money to support us in retirement. So that's 299 00:15:52,440 --> 00:15:55,240 Speaker 1: sort of our chances of running into another star or 300 00:15:55,640 --> 00:15:58,440 Speaker 1: star colliining nero us doesn't seem very likely. But let's 301 00:15:58,440 --> 00:16:00,920 Speaker 1: talk about maybe what would happen if our star did 302 00:16:00,960 --> 00:16:03,600 Speaker 1: collide with another star, or generally what happens when stars 303 00:16:03,640 --> 00:16:06,360 Speaker 1: collide with each other. Yeah, it can be pretty dramatic, 304 00:16:06,360 --> 00:16:09,680 Speaker 1: But it also depends on exactly how fast the collision 305 00:16:09,720 --> 00:16:12,920 Speaker 1: happens and whether there's actually a collision or just sort 306 00:16:12,920 --> 00:16:15,160 Speaker 1: of a near miss. You might feel a little bit 307 00:16:15,160 --> 00:16:17,120 Speaker 1: relieved to think, well, our son is not going to 308 00:16:17,200 --> 00:16:19,360 Speaker 1: hit any other stars for another you know, ten to 309 00:16:19,400 --> 00:16:22,840 Speaker 1: the eighteen years, so I can relax. But our Solar 310 00:16:22,880 --> 00:16:26,040 Speaker 1: system might be seriously impacted. Even if just another star 311 00:16:26,160 --> 00:16:29,040 Speaker 1: comes somewhere near us. You could have a real impact 312 00:16:29,080 --> 00:16:31,280 Speaker 1: on our lives. Right, Like, they don't have to actually 313 00:16:31,320 --> 00:16:33,880 Speaker 1: touch each other for there to be a disaster, right yeah, 314 00:16:33,920 --> 00:16:37,160 Speaker 1: because those stars are huge sources of gravity and they're 315 00:16:37,200 --> 00:16:39,800 Speaker 1: already sort of tugging on each other a little bit. 316 00:16:40,080 --> 00:16:42,760 Speaker 1: Remember that our Solar system doesn't just have a star 317 00:16:42,840 --> 00:16:45,560 Speaker 1: and a bunch of planets. It's surrounded by this vast 318 00:16:45,720 --> 00:16:49,160 Speaker 1: cloud of trillions of icy objects. We call this the 319 00:16:49,320 --> 00:16:51,800 Speaker 1: ort cloud, and we think that's where comments come from. 320 00:16:51,880 --> 00:16:54,720 Speaker 1: And so if another star passes anywhere near our Solar system, 321 00:16:54,760 --> 00:16:56,880 Speaker 1: it can perturb some of those and then they can 322 00:16:57,000 --> 00:17:00,240 Speaker 1: fall into the gravitational well of our Solar system, picking 323 00:17:00,280 --> 00:17:02,840 Speaker 1: up a huge amount of speed and energy as they 324 00:17:02,880 --> 00:17:06,119 Speaker 1: fall in zooming down through the inner Solar System and 325 00:17:06,200 --> 00:17:08,600 Speaker 1: right past the planets, and these comments, if they hit 326 00:17:08,640 --> 00:17:11,880 Speaker 1: the Earth, for example, they could wipe out humanity. It's 327 00:17:11,880 --> 00:17:14,639 Speaker 1: an incredible source of energy in a real danger. So 328 00:17:14,680 --> 00:17:17,720 Speaker 1: if a star comes nearby, they could disturb one of those, 329 00:17:17,760 --> 00:17:19,720 Speaker 1: and if they come even closer, they could even like 330 00:17:19,880 --> 00:17:22,879 Speaker 1: toss a planet out of the Solar system. Wow, you 331 00:17:22,920 --> 00:17:25,880 Speaker 1: could get booted off the island or the Solar system. Yeah, 332 00:17:25,880 --> 00:17:28,679 Speaker 1: because our orbits are fairly fragile. We have to be 333 00:17:28,720 --> 00:17:31,840 Speaker 1: going in the right direction, at the right velocity and 334 00:17:31,960 --> 00:17:35,439 Speaker 1: at the right radius for everything to balance. So orbits 335 00:17:35,480 --> 00:17:37,639 Speaker 1: are not that hard to perturb and they're sort of 336 00:17:37,720 --> 00:17:40,360 Speaker 1: hard to recover. And so you're saying that even if 337 00:17:40,480 --> 00:17:43,879 Speaker 1: our star doesn't collide with another star, just having a 338 00:17:43,920 --> 00:17:46,960 Speaker 1: near miss could be potentially fatal to us. It could 339 00:17:47,000 --> 00:17:49,479 Speaker 1: be fatally Earth could get tossed out of our Solar 340 00:17:49,480 --> 00:17:52,520 Speaker 1: system into the galaxy itself without a star, or we 341 00:17:52,520 --> 00:17:55,440 Speaker 1: could get hit by a comment that gets perturbed by 342 00:17:55,440 --> 00:17:58,320 Speaker 1: a passing star. So how close do we need to 343 00:17:58,440 --> 00:18:01,720 Speaker 1: come to another star for it to be sort of dangerous? 344 00:18:01,800 --> 00:18:03,639 Speaker 1: In order for the Earth to get like tossed out 345 00:18:03,680 --> 00:18:05,800 Speaker 1: of orbit, the star would need to come sort of 346 00:18:05,960 --> 00:18:08,480 Speaker 1: within a few au of our star in order to 347 00:18:08,560 --> 00:18:11,000 Speaker 1: have like the gravity to really perturb the orbit, in 348 00:18:11,080 --> 00:18:14,040 Speaker 1: order to perturb the Org cloud. Well, we don't really know. 349 00:18:14,119 --> 00:18:16,879 Speaker 1: And there's actually a lot of really interesting theories that 350 00:18:16,960 --> 00:18:19,400 Speaker 1: suggests that there might be another star out there. It's 351 00:18:19,400 --> 00:18:23,000 Speaker 1: called the Nemesis that every like thirty million years swoops 352 00:18:23,040 --> 00:18:26,440 Speaker 1: around near our Sun and perturbs all those objects in 353 00:18:26,480 --> 00:18:29,359 Speaker 1: the Org cloud and rains down comments on us. People 354 00:18:29,359 --> 00:18:32,760 Speaker 1: look back at the history of commentary impacts on Earth 355 00:18:33,000 --> 00:18:35,000 Speaker 1: and they think they might see like a pattern, like 356 00:18:35,040 --> 00:18:38,160 Speaker 1: a thirty million years cycle, and that suggests there could 357 00:18:38,200 --> 00:18:41,200 Speaker 1: be something out there doing this regularly every thirty million years. 358 00:18:41,320 --> 00:18:43,120 Speaker 1: Maybe that's how we got our water. It was one 359 00:18:43,160 --> 00:18:46,120 Speaker 1: of these commage howers, right, Yeah, it could be exactly 360 00:18:46,119 --> 00:18:48,560 Speaker 1: a lot of the water on Earth came from comets, 361 00:18:48,640 --> 00:18:51,639 Speaker 1: and so maybe you know, fed us, nurtured us, and 362 00:18:51,640 --> 00:18:54,040 Speaker 1: then it's going to come back and kill us. Well, 363 00:18:54,040 --> 00:18:56,680 Speaker 1: we just have to get umbrellas to fend off all 364 00:18:56,680 --> 00:19:01,080 Speaker 1: that water rain and down giant ice block. So you're saying, 365 00:19:01,119 --> 00:19:03,040 Speaker 1: if another star comes within a few a U s, 366 00:19:03,080 --> 00:19:05,920 Speaker 1: and a U is sort of the distance between the 367 00:19:05,960 --> 00:19:08,440 Speaker 1: Sun and the Earth, right, So if it comes within 368 00:19:08,480 --> 00:19:10,719 Speaker 1: a few distances of Earth and the Sun, then it 369 00:19:10,720 --> 00:19:13,800 Speaker 1: could be big trouble. But if it comes far away, 370 00:19:13,840 --> 00:19:17,320 Speaker 1: it could still cause some trouble by raining comments on us. Yeah, 371 00:19:17,320 --> 00:19:19,359 Speaker 1: anything less than like a light year or so, it 372 00:19:19,359 --> 00:19:22,199 Speaker 1: could be serious problems. What about a direct hit? What 373 00:19:22,200 --> 00:19:24,560 Speaker 1: would happen when two stars sort of directly hit each other, 374 00:19:24,880 --> 00:19:27,879 Speaker 1: So this is much more exciting. If another star comes 375 00:19:27,920 --> 00:19:30,919 Speaker 1: in sort of at high speed, then basically what's going 376 00:19:30,960 --> 00:19:33,479 Speaker 1: to happen is the Sun would be destroyed. If you imagine, 377 00:19:33,520 --> 00:19:36,600 Speaker 1: for example, like a white dwarf, which is a solar remnant, 378 00:19:36,640 --> 00:19:39,359 Speaker 1: like a big hot chunk of metal, and it plows 379 00:19:39,440 --> 00:19:42,360 Speaker 1: into the Sun, and people actually have done simulations about this, 380 00:19:42,520 --> 00:19:45,240 Speaker 1: it would trigger the whole Sun to start burning. Currently, 381 00:19:45,280 --> 00:19:47,560 Speaker 1: fusion is happening, but mostly at the heart of the Sun. 382 00:19:47,760 --> 00:19:50,159 Speaker 1: If a white dwarf comes in, it would increase the 383 00:19:50,160 --> 00:19:52,919 Speaker 1: pressure and the temperature of the Sun so dramatically that 384 00:19:53,000 --> 00:19:55,560 Speaker 1: it would release as much energy through fusion in an 385 00:19:55,600 --> 00:19:59,280 Speaker 1: hour as it would have otherwise in a hundred million years. 386 00:20:00,200 --> 00:20:02,240 Speaker 1: You mean, like just from the impact. It would sort 387 00:20:02,240 --> 00:20:05,320 Speaker 1: of as it's impacting or crashing into the Sun, it 388 00:20:05,320 --> 00:20:09,159 Speaker 1: would actually cause fusion on its way in exactly, it 389 00:20:09,160 --> 00:20:11,680 Speaker 1: would increase the temperature, and so the rate of fusion 390 00:20:11,880 --> 00:20:14,680 Speaker 1: depends on the temperature. So basically the Sun would just 391 00:20:14,720 --> 00:20:17,560 Speaker 1: like burn up super duper fast as this thing passes 392 00:20:17,560 --> 00:20:20,520 Speaker 1: through it. But then it would also explode like that 393 00:20:20,600 --> 00:20:23,600 Speaker 1: much fusion would blow the star out, and so a 394 00:20:23,720 --> 00:20:26,639 Speaker 1: huge chunk of the Sun's energy would be burned up 395 00:20:26,840 --> 00:20:29,160 Speaker 1: in this rapid fusion. A lot of it would get 396 00:20:29,160 --> 00:20:31,960 Speaker 1: blown out because of the radiation from this fusion. And 397 00:20:32,000 --> 00:20:34,560 Speaker 1: then also the Sun might lose its cohesion, like it 398 00:20:34,640 --> 00:20:37,080 Speaker 1: might get sprayed out, like you know, an egg yolk 399 00:20:37,320 --> 00:20:41,280 Speaker 1: or something against the wall sprayed out into the galaxy. Whoa, 400 00:20:42,000 --> 00:20:44,479 Speaker 1: and there goes plans for an over easy solar system. 401 00:20:45,280 --> 00:20:47,000 Speaker 1: But I guess you're saying, you know, the Sun is 402 00:20:47,040 --> 00:20:49,520 Speaker 1: not solid, right, It's a sort of a giant cloud 403 00:20:49,520 --> 00:20:52,119 Speaker 1: of plasma, and so when something crashes into it, it it 404 00:20:52,240 --> 00:20:55,520 Speaker 1: doesn't like crack or break or you know, sort of 405 00:20:55,640 --> 00:20:58,280 Speaker 1: break apart. It sort of takes in whatever it comes 406 00:20:58,280 --> 00:21:00,880 Speaker 1: at it, and maybe that's a lot of energy. Then 407 00:21:00,880 --> 00:21:03,360 Speaker 1: it starts to burn faster. Yeah, but if it comes 408 00:21:03,400 --> 00:21:05,320 Speaker 1: in with enough energy, it could also like pop that 409 00:21:05,440 --> 00:21:08,080 Speaker 1: yoke and spread it everywhere. Imagine like, you know, a 410 00:21:08,080 --> 00:21:11,399 Speaker 1: big fraction of the Sun getting ejected out into the 411 00:21:11,400 --> 00:21:14,560 Speaker 1: Solar system. It could just like totally vaporize a planet. 412 00:21:14,600 --> 00:21:16,520 Speaker 1: What about if it comes in at low speed. If 413 00:21:16,520 --> 00:21:18,520 Speaker 1: it comes in at a smaller speed, then there's a 414 00:21:18,600 --> 00:21:21,320 Speaker 1: chance that it wouldn't actually impact the Sun, that the 415 00:21:21,320 --> 00:21:23,720 Speaker 1: Sun could capture it, that you could end up with 416 00:21:23,800 --> 00:21:26,520 Speaker 1: like a binary star system, or if it comes in 417 00:21:26,560 --> 00:21:28,919 Speaker 1: at just the right angle, you could just get absorbed. 418 00:21:29,200 --> 00:21:31,440 Speaker 1: It's sort of like you know, two yolks forming one 419 00:21:31,600 --> 00:21:34,280 Speaker 1: mega yoke. If it comes in sort of gently and gradually, 420 00:21:34,640 --> 00:21:36,760 Speaker 1: then the two stars could just sort of like merge 421 00:21:36,800 --> 00:21:40,720 Speaker 1: into one bigger star. Interesting, like it can suck it 422 00:21:40,760 --> 00:21:42,720 Speaker 1: in kind of, yeah, it could just suck it in 423 00:21:42,960 --> 00:21:45,680 Speaker 1: because it's not that much interesting structure to the Sun. 424 00:21:45,920 --> 00:21:48,359 Speaker 1: We don't actually really know that much about the convection 425 00:21:48,440 --> 00:21:50,800 Speaker 1: and the currents inside the Sun because things like the 426 00:21:50,840 --> 00:21:53,240 Speaker 1: solar magnetic field are still a mystery to us. But 427 00:21:53,320 --> 00:21:55,399 Speaker 1: in our best model is that it's basically just a 428 00:21:55,440 --> 00:21:58,000 Speaker 1: bag of hydrogen. So you add another bag of hydrogen 429 00:21:58,040 --> 00:21:59,680 Speaker 1: to it, and you know it take a little while 430 00:21:59,760 --> 00:22:01,920 Speaker 1: to stay able. Eyes well, get brighter and have shock 431 00:22:02,000 --> 00:22:04,040 Speaker 1: waves and all sorts of stuff for a few million years, 432 00:22:04,080 --> 00:22:06,440 Speaker 1: but eventually we'd settle down and just be a bigger star. 433 00:22:06,640 --> 00:22:08,159 Speaker 1: So I guess what you're saying is that, you know, 434 00:22:08,200 --> 00:22:10,240 Speaker 1: the collision itself is sort of rare, and you would 435 00:22:10,240 --> 00:22:12,800 Speaker 1: eat sort of a high speed and just enough luck 436 00:22:12,880 --> 00:22:15,520 Speaker 1: to actually have the two stars hit each other. But 437 00:22:15,600 --> 00:22:17,800 Speaker 1: a lot of interesting things canna happen even if there 438 00:22:17,800 --> 00:22:20,359 Speaker 1: are near missus. Yeah, even if they are near missus. 439 00:22:20,440 --> 00:22:22,840 Speaker 1: So if this is star coming near at anytime soon, 440 00:22:22,960 --> 00:22:25,439 Speaker 1: it's going to be dramatic no matter what happens. All right, Well, 441 00:22:25,520 --> 00:22:28,000 Speaker 1: let's talk about other places in the universe where collisions 442 00:22:28,080 --> 00:22:31,800 Speaker 1: between stars are actually inevitable. But first let's take a 443 00:22:31,920 --> 00:22:47,679 Speaker 1: quick break. Alright, we're talking about when stars collide, the 444 00:22:47,720 --> 00:22:49,879 Speaker 1: ones in space, not the ones here on earth that 445 00:22:49,960 --> 00:22:53,680 Speaker 1: make movies, although those are the best crossover events, right, Yeah, 446 00:22:54,119 --> 00:22:57,480 Speaker 1: it does make the best headlines Batman versus Superman, Marvel 447 00:22:57,640 --> 00:23:00,600 Speaker 1: versus DC. When does that movie come? Now? I'm looking 448 00:23:00,600 --> 00:23:03,879 Speaker 1: forward to. Yeah, I know, but we're talking about stars colliding, 449 00:23:04,000 --> 00:23:06,399 Speaker 1: and we talked about how they're sort of rare in 450 00:23:06,440 --> 00:23:09,119 Speaker 1: our neighborhood, but there they happen a lot in other 451 00:23:09,200 --> 00:23:11,600 Speaker 1: places in the galaxy, in the center of the galaxy 452 00:23:11,640 --> 00:23:14,480 Speaker 1: and colobular clusters, and there are sort of um other 453 00:23:14,520 --> 00:23:18,399 Speaker 1: particular situations where these collisions happen a lot and almost 454 00:23:18,440 --> 00:23:20,960 Speaker 1: all the time. Yeah, and our solar system is a 455 00:23:21,040 --> 00:23:23,959 Speaker 1: little bit unusual because it just has one star. If 456 00:23:24,000 --> 00:23:25,840 Speaker 1: you look out into the night sky, turns out that 457 00:23:25,880 --> 00:23:28,760 Speaker 1: a lot of the solar systems out there are binary 458 00:23:28,840 --> 00:23:32,480 Speaker 1: star systems. Stars that were born together, like near each other, 459 00:23:32,520 --> 00:23:36,119 Speaker 1: from the same huge cloud of gas and dust. Doesn't 460 00:23:36,119 --> 00:23:39,680 Speaker 1: always just coalesce into a single star. Sometimes you get 461 00:23:39,800 --> 00:23:42,879 Speaker 1: two dense points there and you get two stars forming. 462 00:23:43,040 --> 00:23:45,400 Speaker 1: It's a lot more common than we used to think. 463 00:23:45,480 --> 00:23:48,040 Speaker 1: And the binary star system like that is really cool. 464 00:23:48,119 --> 00:23:51,600 Speaker 1: It's fun to imagine, but also it's not stable. That 465 00:23:51,680 --> 00:23:56,200 Speaker 1: kind of situation can't last forever. Eventually those two stars 466 00:23:56,320 --> 00:24:00,399 Speaker 1: will collide. Interesting, Now, why are two stars sy them's 467 00:24:00,760 --> 00:24:04,440 Speaker 1: unstable like it's our sources them unstable? Or are all 468 00:24:04,600 --> 00:24:07,280 Speaker 1: orbits unstable? Or is it just the ones between two 469 00:24:07,280 --> 00:24:12,280 Speaker 1: stars that are particularly unstable? Fundamentally, all orbits are unstable. 470 00:24:12,359 --> 00:24:15,480 Speaker 1: And the reason is that when you move in a circle, 471 00:24:15,960 --> 00:24:20,480 Speaker 1: that's acceleration like acceleration is anytime you change your velocity, 472 00:24:20,600 --> 00:24:23,199 Speaker 1: and not just the magnitude of your velocity, not just 473 00:24:23,240 --> 00:24:25,920 Speaker 1: your speed, but your direction. So when the Earth is 474 00:24:25,960 --> 00:24:28,879 Speaker 1: moving around the Sun, for example, it's accelerating. Is a 475 00:24:29,000 --> 00:24:31,919 Speaker 1: velocity vector goes from pointing in one way to pointing 476 00:24:32,040 --> 00:24:36,720 Speaker 1: another way. And anytime there's acceleration, there is radiation. Like 477 00:24:36,760 --> 00:24:39,760 Speaker 1: when an electron turns and goes left, it has to 478 00:24:39,840 --> 00:24:42,919 Speaker 1: kick off a photon in the other direction it radiates. 479 00:24:43,240 --> 00:24:45,920 Speaker 1: This is actually a major puzzle In early quantum mechanics, 480 00:24:45,920 --> 00:24:49,399 Speaker 1: people were wondering, like, why do electrons orbit the atom 481 00:24:49,440 --> 00:24:51,800 Speaker 1: in a stable way? Why don't they emit photons and 482 00:24:51,840 --> 00:24:54,479 Speaker 1: just collapse into the center of the atom. Now, of 483 00:24:54,480 --> 00:24:56,840 Speaker 1: course we understand the answer to that is quantum mechanics 484 00:24:56,840 --> 00:25:00,800 Speaker 1: prevents it from happening. But what about planets. When planets 485 00:25:00,880 --> 00:25:03,679 Speaker 1: orbit a star, or when stars orbit each other, or 486 00:25:03,680 --> 00:25:06,680 Speaker 1: two black holes orbit each other, they are giving off 487 00:25:06,960 --> 00:25:13,399 Speaker 1: gravitational radiation. They are emitting gravitational waves. Any acceleration of 488 00:25:13,440 --> 00:25:18,199 Speaker 1: an object emits gravitational waves. So two huge objects in 489 00:25:18,280 --> 00:25:22,439 Speaker 1: orbit around each other eventually will radiate away some of 490 00:25:22,480 --> 00:25:25,960 Speaker 1: that energy and collapse into the center. Interesting, and that's 491 00:25:25,960 --> 00:25:28,399 Speaker 1: sort of true also for even our Solar system, right like, 492 00:25:28,440 --> 00:25:31,760 Speaker 1: eventually in the far far far far far future are 493 00:25:31,880 --> 00:25:34,280 Speaker 1: orbit it will eventually have fall into the Sun. That 494 00:25:34,480 --> 00:25:37,040 Speaker 1: is true. There's competing effects there because the Earth is 495 00:25:37,080 --> 00:25:39,600 Speaker 1: not nearly as massive as another star, so it doesn't 496 00:25:39,640 --> 00:25:43,040 Speaker 1: generate as much gravitational radiation. But you know, even the 497 00:25:43,080 --> 00:25:45,760 Speaker 1: Earth moving through sort of the solar wind, right the 498 00:25:45,760 --> 00:25:48,600 Speaker 1: Solar system is not empty. As we move through that stuff, 499 00:25:48,640 --> 00:25:51,560 Speaker 1: we lose energy and so we are slowing down. So 500 00:25:51,600 --> 00:25:55,240 Speaker 1: eventually the Earth will fall into the Sun. But that's 501 00:25:55,240 --> 00:25:57,000 Speaker 1: going to happen in a long long time. But when 502 00:25:57,000 --> 00:26:00,440 Speaker 1: two stars orbit each other, two very massive objects, there's 503 00:26:00,480 --> 00:26:04,240 Speaker 1: a lot more gravitational radiation emitted. So two stars orbiting 504 00:26:04,280 --> 00:26:07,360 Speaker 1: each other, that orbit will decay faster than just planets 505 00:26:07,400 --> 00:26:10,360 Speaker 1: orbiting a star. Interesting, and so we we also had 506 00:26:10,440 --> 00:26:13,200 Speaker 1: a whole episode about binary star systems and multi star 507 00:26:13,280 --> 00:26:17,160 Speaker 1: systems and we talked about how unstable and fun they are. 508 00:26:17,520 --> 00:26:19,040 Speaker 1: But you're saying that sort of if you have a 509 00:26:19,040 --> 00:26:22,320 Speaker 1: binary star system, pretty soon it will become I guess 510 00:26:22,320 --> 00:26:25,160 Speaker 1: a one star system. When the two stars collide, either 511 00:26:25,240 --> 00:26:27,399 Speaker 1: something will come by and perturb it, like you have 512 00:26:27,440 --> 00:26:29,680 Speaker 1: a planet and the planet will get thrown out, or 513 00:26:29,800 --> 00:26:31,960 Speaker 1: it will perturb the orbits of the stars around each 514 00:26:32,000 --> 00:26:34,159 Speaker 1: other and they'll just sort of like run off in 515 00:26:34,200 --> 00:26:36,800 Speaker 1: other directions. But if they don't, if nothing comes along 516 00:26:36,840 --> 00:26:39,640 Speaker 1: to perturb it, then eventually they will spiral into each 517 00:26:39,640 --> 00:26:43,480 Speaker 1: other because they'll lose that relative energy and they will collide. 518 00:26:44,080 --> 00:26:48,719 Speaker 1: It's inevitable. Well, it's um kind of a tragic I guess, 519 00:26:49,000 --> 00:26:51,280 Speaker 1: because you know, the binary star systems are pretty cool. 520 00:26:51,280 --> 00:26:54,000 Speaker 1: They're pretty beautiful, right like in Star Wars when Luke 521 00:26:54,040 --> 00:26:58,000 Speaker 1: Skywalker looks out into the sunset he sees two stars. Yeah, 522 00:26:58,040 --> 00:27:01,680 Speaker 1: they are beautiful, but also they're lesions are beautiful. These 523 00:27:01,760 --> 00:27:05,560 Speaker 1: cataclysmic events are really important for creating the elements that 524 00:27:05,600 --> 00:27:08,359 Speaker 1: helped make up you and me and the very nature 525 00:27:08,400 --> 00:27:10,960 Speaker 1: of the universe. So I'm glad that these events exist. 526 00:27:11,000 --> 00:27:13,600 Speaker 1: They're pretty awesome to study, as long as we know 527 00:27:13,640 --> 00:27:16,159 Speaker 1: we're not living around one of those stars. Yes, my 528 00:27:16,240 --> 00:27:19,359 Speaker 1: story now looked Skywalker. That's right, not in my star yard. 529 00:27:19,600 --> 00:27:23,119 Speaker 1: And actually one kind of supernova out there in the 530 00:27:23,200 --> 00:27:26,399 Speaker 1: universe is due to stars colliding, right, It's like, not 531 00:27:26,480 --> 00:27:29,000 Speaker 1: all supernovas are just stars imploding. Some of them come 532 00:27:29,080 --> 00:27:31,840 Speaker 1: from stars colliding. Yeah, one of the most important kinds 533 00:27:31,880 --> 00:27:35,800 Speaker 1: of supernova type one A come exactly when that happens. 534 00:27:35,840 --> 00:27:38,359 Speaker 1: You have a binary star system and one of the 535 00:27:38,400 --> 00:27:42,240 Speaker 1: stars has died distinguished itself, but it wasn't big enough 536 00:27:42,280 --> 00:27:44,359 Speaker 1: to go all the way down to a black hole. 537 00:27:44,600 --> 00:27:46,920 Speaker 1: Like it burned and it generated a lot of light, 538 00:27:47,000 --> 00:27:48,439 Speaker 1: and it came to the end of its life and 539 00:27:48,480 --> 00:27:51,440 Speaker 1: it blew out its outer layers, and what's left is 540 00:27:51,480 --> 00:27:54,359 Speaker 1: a hot core, this thing called a white dwarf. And 541 00:27:54,359 --> 00:27:56,360 Speaker 1: this is like the future of our son. Our son 542 00:27:56,520 --> 00:27:59,119 Speaker 1: doesn't have enough energy in it to go supernova or 543 00:27:59,200 --> 00:28:01,359 Speaker 1: to go black hole. It's just gonna sort of like 544 00:28:01,440 --> 00:28:04,520 Speaker 1: burn explode out its outer layers and then leave us 545 00:28:04,520 --> 00:28:07,280 Speaker 1: with a hot, dense mass at the center, not dense 546 00:28:07,400 --> 00:28:09,920 Speaker 1: enough to become a neutron star or to go supernova 547 00:28:10,160 --> 00:28:12,439 Speaker 1: or become a black hole. So that's sort of the 548 00:28:12,440 --> 00:28:15,000 Speaker 1: future of our star and stars like it. Like it 549 00:28:15,080 --> 00:28:18,080 Speaker 1: just becomes like a white hot object floating in space, right, 550 00:28:18,119 --> 00:28:21,040 Speaker 1: made out of sort of heavier elements. Yeah, it's just 551 00:28:21,080 --> 00:28:23,720 Speaker 1: like white hot metal, you know, like carbon or wherever 552 00:28:23,800 --> 00:28:27,800 Speaker 1: the process stopped. It's the hot heavy core of the star. Remember, 553 00:28:27,840 --> 00:28:30,560 Speaker 1: these stars start burning hydrogen and then they make helium, 554 00:28:30,720 --> 00:28:33,159 Speaker 1: that they make heavier elements, and they just keep burning 555 00:28:33,160 --> 00:28:36,000 Speaker 1: as long as they can. But eventually they make so 556 00:28:36,040 --> 00:28:39,120 Speaker 1: many heavy metals that they can no longer fuse that 557 00:28:39,160 --> 00:28:41,280 Speaker 1: they could basically go out. But what you're left with 558 00:28:41,440 --> 00:28:44,440 Speaker 1: is a huge white, hot chunk of those heavy metals 559 00:28:44,480 --> 00:28:47,080 Speaker 1: just glowing in space. No more fusion happening. So it's 560 00:28:47,120 --> 00:28:48,760 Speaker 1: sort of like a dead end for a star, and 561 00:28:48,800 --> 00:28:52,080 Speaker 1: it just sits there, radiating away its energy until eventually 562 00:28:52,080 --> 00:28:54,600 Speaker 1: it cools. It takes like trillions of years to become 563 00:28:54,600 --> 00:28:58,920 Speaker 1: a black dwarf unless it gets a second act, unless 564 00:28:58,960 --> 00:29:01,200 Speaker 1: it makes a comeback and then somebody cast him in 565 00:29:01,320 --> 00:29:04,120 Speaker 1: an indie movie that gets a critical acclaim. That's right. 566 00:29:04,160 --> 00:29:07,320 Speaker 1: We call this going John Travolta. And what happens is 567 00:29:07,400 --> 00:29:10,560 Speaker 1: that if you have another big star nearby, then this 568 00:29:10,640 --> 00:29:13,440 Speaker 1: white dwarf can steal some of its mass and so 569 00:29:13,520 --> 00:29:15,880 Speaker 1: it like gobbles up the outer layers of like a 570 00:29:15,920 --> 00:29:19,160 Speaker 1: red giant. And so this happens, especially when a white 571 00:29:19,200 --> 00:29:21,920 Speaker 1: dwarf is part of a binary star system, it can 572 00:29:22,000 --> 00:29:24,320 Speaker 1: gobble up some of the mass of the other star 573 00:29:24,440 --> 00:29:27,200 Speaker 1: when it gets close enough and then it has enough 574 00:29:27,240 --> 00:29:29,760 Speaker 1: stuff and it to go supernova. So the supernova that 575 00:29:29,800 --> 00:29:32,280 Speaker 1: didn't happen during the first part of its life can 576 00:29:32,280 --> 00:29:35,600 Speaker 1: now get triggered after the star has basically already died 577 00:29:35,640 --> 00:29:39,280 Speaker 1: because it's getting this additional mass, this extra helping of stuff, 578 00:29:39,320 --> 00:29:40,920 Speaker 1: and it sucks it out of the other star. It's 579 00:29:40,960 --> 00:29:43,440 Speaker 1: just from gravity, right, Like they're near each other, they're 580 00:29:43,440 --> 00:29:46,280 Speaker 1: circling around each other, and it's just the gravity. Sometimes 581 00:29:46,320 --> 00:29:48,600 Speaker 1: the stuff from the red giant sort of hops over 582 00:29:48,720 --> 00:29:50,800 Speaker 1: to the white wharf. Yeah, because the stars have to 583 00:29:50,840 --> 00:29:53,360 Speaker 1: get closer and closer as time goes on, because they're 584 00:29:53,440 --> 00:29:56,520 Speaker 1: radiating away energy, and because that other stars also can 585 00:29:56,640 --> 00:29:59,800 Speaker 1: be expanding its radius. Stars get bigger as they get older, 586 00:30:00,000 --> 00:30:01,400 Speaker 1: and so now the white dwarfs is just gonna be 587 00:30:01,440 --> 00:30:03,600 Speaker 1: like siphoning off some of that mass and the outer 588 00:30:03,720 --> 00:30:06,000 Speaker 1: layers of that star. And so at somebody gets enough 589 00:30:06,000 --> 00:30:08,720 Speaker 1: and then it collapses, right or it doesn't start burning again. 590 00:30:08,760 --> 00:30:10,920 Speaker 1: It just sort of collapses, right, It collapses into a 591 00:30:10,960 --> 00:30:13,840 Speaker 1: supernova and goes boom, yeah, m m yeah, like the 592 00:30:13,960 --> 00:30:17,040 Speaker 1: it turns into iron, right, Like it gets enough pressure 593 00:30:17,080 --> 00:30:20,080 Speaker 1: to actually collapse. What happens to the core depends a 594 00:30:20,080 --> 00:30:23,480 Speaker 1: lot on where it's stopped in its fusion process. But yeah, 595 00:30:23,520 --> 00:30:26,600 Speaker 1: the key is but now gravity can overcome the structure 596 00:30:26,600 --> 00:30:29,200 Speaker 1: of that material, it can compress it even further, and 597 00:30:29,240 --> 00:30:32,120 Speaker 1: so you get this shock wave which causes the supernova. 598 00:30:32,320 --> 00:30:36,120 Speaker 1: Mm hmm. Interesting And so that's the type one A supernovas. 599 00:30:36,160 --> 00:30:39,400 Speaker 1: So it's not like a star naturally exploding. It's like 600 00:30:39,520 --> 00:30:41,920 Speaker 1: it's like another star came in and like excited it, 601 00:30:42,000 --> 00:30:45,240 Speaker 1: and it then it collapsed right exactly. And it's fascinating 602 00:30:45,280 --> 00:30:49,800 Speaker 1: because these are really really important for measuring distances. Like 603 00:30:49,880 --> 00:30:52,320 Speaker 1: when that happens, it happens in a very specific way, 604 00:30:52,800 --> 00:30:55,760 Speaker 1: and the stars have this peak brightness. The whole thing 605 00:30:55,840 --> 00:30:58,080 Speaker 1: lasts just a few days or weeks, depending on the star, 606 00:30:58,400 --> 00:31:00,840 Speaker 1: but we can calibrate that brightness, you know, how bright 607 00:31:00,920 --> 00:31:03,320 Speaker 1: these things are, which means when we see them here 608 00:31:03,360 --> 00:31:05,680 Speaker 1: on Earth, we can tell how far away they are 609 00:31:05,920 --> 00:31:09,160 Speaker 1: by measuring how bright they appear in our telescopes. So 610 00:31:09,200 --> 00:31:12,440 Speaker 1: they've become a really really useful way to measure distances 611 00:31:12,480 --> 00:31:16,480 Speaker 1: to other galaxies, which are otherwise very hard to estimate. Right, Yeah, 612 00:31:16,520 --> 00:31:19,240 Speaker 1: because I think you know, we understand stars so well 613 00:31:19,280 --> 00:31:21,160 Speaker 1: now at this at this point that we know that 614 00:31:21,640 --> 00:31:23,480 Speaker 1: if we see a certain process, we know that it 615 00:31:23,560 --> 00:31:26,240 Speaker 1: involved the star of this size and another star of 616 00:31:26,320 --> 00:31:28,360 Speaker 1: that size, and it couldn't have happened any other way 617 00:31:28,400 --> 00:31:30,720 Speaker 1: with a bigger or a smaller star. So sort of 618 00:31:30,760 --> 00:31:32,880 Speaker 1: we can sort of standardize it, right, and we can 619 00:31:33,000 --> 00:31:36,560 Speaker 1: say that little bright spot there, that's when this size 620 00:31:36,600 --> 00:31:39,040 Speaker 1: star collided with that size star, and that lets us 621 00:31:39,120 --> 00:31:41,600 Speaker 1: know just exactly how far away it is. Yeah, it's 622 00:31:41,600 --> 00:31:44,040 Speaker 1: really pretty cool. We have a whole episode about how 623 00:31:44,080 --> 00:31:46,440 Speaker 1: to know the distance two stars. You should check that out, 624 00:31:46,800 --> 00:31:49,760 Speaker 1: and it requires, you know, calibrating. We using other ideas 625 00:31:49,800 --> 00:31:54,320 Speaker 1: and other strategies for measuring distances and overlapping ladders, so 626 00:31:54,400 --> 00:31:57,400 Speaker 1: we can cause calibrate different metrics. It's really like an 627 00:31:57,400 --> 00:31:59,840 Speaker 1: amazing tour to force of modern science. And so that 628 00:32:00,160 --> 00:32:03,320 Speaker 1: one interesting thing that can happen when two stars glided. 629 00:32:03,440 --> 00:32:06,440 Speaker 1: What are some other interesting mergers or collisions that we 630 00:32:06,480 --> 00:32:08,760 Speaker 1: see out there in the universe. So something we've discovered 631 00:32:08,800 --> 00:32:12,640 Speaker 1: recently is that we can actually see this gravitational radiation 632 00:32:13,040 --> 00:32:16,720 Speaker 1: when stars collide. Einstein predicted this a long long time 633 00:32:16,760 --> 00:32:19,560 Speaker 1: ago that when two stars aren't orbited around each other, 634 00:32:19,600 --> 00:32:23,400 Speaker 1: they will give off gravitational radiation, and that radiation increases 635 00:32:23,440 --> 00:32:25,680 Speaker 1: as the stars get closer and closer and they spin 636 00:32:25,720 --> 00:32:28,320 Speaker 1: around each other faster and faster and faster. And this 637 00:32:28,360 --> 00:32:31,280 Speaker 1: was sort of first detected indirectly when people found a 638 00:32:31,360 --> 00:32:34,520 Speaker 1: pair of pulsars that were orbiting each other and they 639 00:32:34,520 --> 00:32:36,600 Speaker 1: watched them over a few years, and they were able 640 00:32:36,640 --> 00:32:39,520 Speaker 1: to tell that the orbit of the pulsars around each other, 641 00:32:39,600 --> 00:32:41,760 Speaker 1: it was getting faster and faster, that they were sort 642 00:32:41,800 --> 00:32:44,880 Speaker 1: of like falling into each other. The distance between them 643 00:32:44,920 --> 00:32:47,479 Speaker 1: was decreasing and they were speeding up how fast they 644 00:32:47,480 --> 00:32:49,800 Speaker 1: were going around each other. That was sort of indirect 645 00:32:50,000 --> 00:32:54,680 Speaker 1: but then decades later we developed this gravitational wave observatory 646 00:32:54,720 --> 00:32:58,200 Speaker 1: that can see those actual ripples in space time itself, 647 00:32:58,440 --> 00:33:01,240 Speaker 1: the radiation of that energy we were talking about when 648 00:33:01,280 --> 00:33:04,160 Speaker 1: two heavy objects orbit each other, and what happens is 649 00:33:04,160 --> 00:33:06,880 Speaker 1: they go faster and faster and eventually they do collide, 650 00:33:07,360 --> 00:33:12,360 Speaker 1: and cataclysmic collisions like between two neutron stars actually happen 651 00:33:12,440 --> 00:33:14,880 Speaker 1: out there in the universe, and we have seen it. Yeah, 652 00:33:14,920 --> 00:33:17,000 Speaker 1: you can sort of picture did like it two bowling 653 00:33:17,040 --> 00:33:19,880 Speaker 1: balls in a giant rubber sheet sort of circling around 654 00:33:19,880 --> 00:33:22,200 Speaker 1: each other, and like, if they're going fast enough, they 655 00:33:22,240 --> 00:33:24,520 Speaker 1: sort caused ripples and in this rubber sheet. And that's 656 00:33:24,560 --> 00:33:26,960 Speaker 1: kind of what these gravitational waves are, right yeah, And 657 00:33:26,960 --> 00:33:28,840 Speaker 1: it's incredible we can see them out here on Earth. 658 00:33:28,880 --> 00:33:33,120 Speaker 1: We have these lasers underground in mile long tunnels, bouncing 659 00:33:33,200 --> 00:33:35,239 Speaker 1: laser beames off of mirrors, and we can tell when 660 00:33:35,280 --> 00:33:37,800 Speaker 1: a gravitational wave has passed because it makes the path 661 00:33:37,840 --> 00:33:41,000 Speaker 1: of that laser a tiny bit longer or a tiny 662 00:33:41,080 --> 00:33:43,880 Speaker 1: bit shorter, because again it's a ripple in space itself. 663 00:33:44,160 --> 00:33:46,680 Speaker 1: We have a whole podcast episode about gravitational waves and 664 00:33:46,680 --> 00:33:48,720 Speaker 1: you should check out. But today what we're talking about 665 00:33:49,000 --> 00:33:51,520 Speaker 1: is the source of those gravitational waves, which can be, 666 00:33:51,560 --> 00:33:55,600 Speaker 1: for example, the collision of two neutron stars. These things 667 00:33:55,640 --> 00:33:58,760 Speaker 1: are crazy objects, things that are like the mass of 668 00:33:58,800 --> 00:34:02,760 Speaker 1: the Sun but compare acted into something like ten kilometers wide. 669 00:34:03,080 --> 00:34:07,080 Speaker 1: So it's just a really incredible dense stellar remnant, like 670 00:34:07,200 --> 00:34:10,319 Speaker 1: left over from when a star burned and collapsed. This 671 00:34:10,400 --> 00:34:12,960 Speaker 1: is the leftover core the neutron star. Now you get 672 00:34:13,000 --> 00:34:15,920 Speaker 1: two of these things zipping around each other and eventually 673 00:34:16,000 --> 00:34:18,719 Speaker 1: slamming into each other as they radiate away all of 674 00:34:18,760 --> 00:34:21,239 Speaker 1: their energy. Yeah, and I think it's a density that 675 00:34:21,280 --> 00:34:23,560 Speaker 1: makes them special, right, It's like they can get so 676 00:34:23,600 --> 00:34:27,640 Speaker 1: close to each other that the gravity gravitational forces are huge, right, 677 00:34:27,680 --> 00:34:29,759 Speaker 1: Like bigger than anything that we can see here in 678 00:34:29,800 --> 00:34:32,800 Speaker 1: our solar system. Yeah, there's like this hierarchy of density 679 00:34:33,080 --> 00:34:35,360 Speaker 1: like a normal star and then like a white dwarf 680 00:34:35,440 --> 00:34:37,040 Speaker 1: is it is very dense, and then if you get 681 00:34:37,160 --> 00:34:39,080 Speaker 1: enough stuff added to the white dwarf, it could become 682 00:34:39,120 --> 00:34:41,800 Speaker 1: like a neutron star. And then of course even denser 683 00:34:41,840 --> 00:34:44,439 Speaker 1: than neutron star is a black hole, which we think 684 00:34:44,480 --> 00:34:46,680 Speaker 1: is the densest thing in the universe. So it just 685 00:34:46,760 --> 00:34:49,600 Speaker 1: all sort of depends on how much stuff the star 686 00:34:49,719 --> 00:34:52,960 Speaker 1: started with, because that determines how much gravity there is, 687 00:34:53,280 --> 00:34:57,040 Speaker 1: which lets you sort of overcome these thresholds compacting something 688 00:34:57,400 --> 00:34:59,560 Speaker 1: like imagine taking the Earth and trying to turn it 689 00:34:59,640 --> 00:35:02,080 Speaker 1: into a neutron star or a black hole. You have 690 00:35:02,120 --> 00:35:04,440 Speaker 1: to really squeeze it down hard to get to be 691 00:35:04,520 --> 00:35:07,560 Speaker 1: that dense Earth mass and black hole would have to 692 00:35:07,560 --> 00:35:10,800 Speaker 1: be like a centimeter wide. How can you possibly squeeze 693 00:35:10,840 --> 00:35:14,080 Speaker 1: the whole Earth down to a centimeter would take incredible forces. 694 00:35:14,239 --> 00:35:15,920 Speaker 1: That's why it's hard to get these things to be 695 00:35:15,960 --> 00:35:18,239 Speaker 1: so dense. You need a huge mass to get the 696 00:35:18,320 --> 00:35:21,719 Speaker 1: gravity to make it that dense, right, yeah. And you 697 00:35:21,719 --> 00:35:24,440 Speaker 1: know when we listen out for those gravitational waves, you 698 00:35:24,440 --> 00:35:27,839 Speaker 1: can sort of reconstruct what happens when these things collide, right, 699 00:35:27,840 --> 00:35:30,400 Speaker 1: Like you can see them from the waves wave pattern. 700 00:35:30,440 --> 00:35:32,680 Speaker 1: You can see them like circling each other slowly, and 701 00:35:32,719 --> 00:35:34,959 Speaker 1: then it picks up speed and it goes faster and faster, 702 00:35:35,000 --> 00:35:36,880 Speaker 1: and then they're like circling each other super fast, and 703 00:35:36,920 --> 00:35:39,120 Speaker 1: then suddenly pop. You actually sort of see the pop 704 00:35:39,160 --> 00:35:42,160 Speaker 1: where they collide with each other, right, yeah. Absolutely, It's 705 00:35:42,239 --> 00:35:44,640 Speaker 1: like those little machines at science museums where you put 706 00:35:44,640 --> 00:35:47,040 Speaker 1: a penny in it slowly rolls around the top of 707 00:35:47,080 --> 00:35:49,160 Speaker 1: a funnel and by the time it spirals down to 708 00:35:49,239 --> 00:35:52,160 Speaker 1: the core, it's going super duper fast. So you have 709 00:35:52,200 --> 00:35:54,439 Speaker 1: two of these things, and you're right, you can see 710 00:35:54,440 --> 00:35:57,319 Speaker 1: this in the gravitational waves. Like the gravitational waves, they 711 00:35:57,320 --> 00:35:59,759 Speaker 1: start out slow and sort of low amplitude, and they 712 00:35:59,760 --> 00:36:02,720 Speaker 1: get louder and louder and faster and faster. The period 713 00:36:03,040 --> 00:36:06,120 Speaker 1: decreases a lot, and so you can see this exactly happening. 714 00:36:06,120 --> 00:36:08,760 Speaker 1: It's it's really sort of incredible. And then when they collide, 715 00:36:09,000 --> 00:36:11,759 Speaker 1: of course you get something very spectacular. Yeah. I was 716 00:36:11,760 --> 00:36:14,160 Speaker 1: gonna use the analogy of like when you flush the toilet, 717 00:36:15,120 --> 00:36:19,200 Speaker 1: and not a science museum demonstration, but like when you 718 00:36:19,200 --> 00:36:21,720 Speaker 1: flush the toilet, right, you see things circling around the drain, 719 00:36:21,920 --> 00:36:24,279 Speaker 1: and then as they get closer, they go faster and faster, 720 00:36:24,320 --> 00:36:26,400 Speaker 1: and then they collide before they fall down the down 721 00:36:26,440 --> 00:36:28,680 Speaker 1: the hall. Yeah. Also, so it depends on what's in 722 00:36:28,719 --> 00:36:31,000 Speaker 1: the toilet, but yes, yeah, well it could be a 723 00:36:31,040 --> 00:36:36,480 Speaker 1: brown dwarf, Yeah, brown dwarf black hole. All right, well, 724 00:36:36,520 --> 00:36:39,160 Speaker 1: let's get into more interesting collisions of stars out there 725 00:36:39,160 --> 00:36:42,560 Speaker 1: in the universe and what our future of our star 726 00:36:42,680 --> 00:36:45,280 Speaker 1: and our galaxy might be. But first let's take another 727 00:36:45,360 --> 00:37:00,400 Speaker 1: quick break. All Right, we're talking about star visions, and 728 00:37:00,440 --> 00:37:02,920 Speaker 1: we're talking about interesting collisions. We've just talked about what 729 00:37:03,000 --> 00:37:05,840 Speaker 1: happens when a neutron star or a black hole, or 730 00:37:05,840 --> 00:37:08,200 Speaker 1: two black holes or two neutron stars collide with each other. 731 00:37:08,520 --> 00:37:10,799 Speaker 1: It's pretty dramatic. What are some of the other fun 732 00:37:10,880 --> 00:37:13,000 Speaker 1: things that can collide out there in the universe. Well, 733 00:37:13,040 --> 00:37:15,680 Speaker 1: we've been talking about neutron stars colliding with each other, 734 00:37:15,840 --> 00:37:18,600 Speaker 1: which is pretty awesome. And before we move on from that, 735 00:37:18,640 --> 00:37:20,600 Speaker 1: I just want to make the point that that's really 736 00:37:20,640 --> 00:37:23,600 Speaker 1: important for the whole nature of the universe. We used 737 00:37:23,640 --> 00:37:26,719 Speaker 1: to think that the production of really heavy metals, things 738 00:37:26,760 --> 00:37:30,240 Speaker 1: heavier than iron, for example, that can't happen inside stars. 739 00:37:30,440 --> 00:37:32,799 Speaker 1: We used to think that mostly happened in supernova. But 740 00:37:32,840 --> 00:37:34,880 Speaker 1: now we actually know different. We know that that mostly 741 00:37:34,920 --> 00:37:38,360 Speaker 1: happens when neutron stars collide. So most of the gold 742 00:37:38,400 --> 00:37:40,959 Speaker 1: and the platinum and the uranium in the universe came 743 00:37:41,080 --> 00:37:44,920 Speaker 1: from events like that, two neutron stars colliding. To me, 744 00:37:45,000 --> 00:37:47,400 Speaker 1: it's just sort of awesome, Like every piece of jewelry 745 00:37:47,440 --> 00:37:49,799 Speaker 1: you see out on somebody's arm or on their ear 746 00:37:49,920 --> 00:37:53,240 Speaker 1: or somebody's finger came from the collision of two neutron 747 00:37:53,320 --> 00:37:56,279 Speaker 1: stars billions of years ago. Interesting, So it's not made 748 00:37:56,280 --> 00:37:59,719 Speaker 1: out to start dust. It's made like start debris or 749 00:38:00,200 --> 00:38:04,399 Speaker 1: you know, star shrapnel, star glitter, dead stars. Kids out 750 00:38:04,400 --> 00:38:09,400 Speaker 1: there playing with glitter. That's all from dead stars. I 751 00:38:09,440 --> 00:38:12,279 Speaker 1: don't know. But what are some other interesting collisions that 752 00:38:12,280 --> 00:38:15,200 Speaker 1: can happen. Well, sometimes a neutron star collides with something 753 00:38:15,280 --> 00:38:17,680 Speaker 1: that's not a neutron star, like when it's a dual 754 00:38:17,680 --> 00:38:20,760 Speaker 1: neutron star collision. You have two objects really dense boom, 755 00:38:20,840 --> 00:38:23,759 Speaker 1: very cataclysmic. Another time, you can get a neutron star 756 00:38:23,840 --> 00:38:26,960 Speaker 1: colliding with something like a red giant. A red giant 757 00:38:26,960 --> 00:38:29,600 Speaker 1: is a star near the end of its life. It's red, 758 00:38:29,640 --> 00:38:31,640 Speaker 1: it's cooled down a little bit, and it's a giant, 759 00:38:31,640 --> 00:38:34,400 Speaker 1: which means that it's like puffed out its outer layers 760 00:38:34,640 --> 00:38:37,160 Speaker 1: because its core has become really heavy, and so now 761 00:38:37,360 --> 00:38:39,799 Speaker 1: fusion is happening more in the outer layers and that's 762 00:38:39,800 --> 00:38:43,759 Speaker 1: the future of our star. So these really big puffy stars, well, 763 00:38:43,760 --> 00:38:46,600 Speaker 1: if a neutron star hits one of these guys, it's 764 00:38:46,640 --> 00:38:49,600 Speaker 1: really interesting. It might just sort of like fall into it, 765 00:38:49,920 --> 00:38:52,399 Speaker 1: and it could just sort of like hang out inside 766 00:38:52,440 --> 00:38:55,080 Speaker 1: the red giant. It's so dense that it could like 767 00:38:55,160 --> 00:38:59,000 Speaker 1: survive inside another star, like it's an orbit around that star, 768 00:38:59,239 --> 00:39:02,120 Speaker 1: but it's actually sort of inside the limits of it. Yeah, 769 00:39:02,160 --> 00:39:06,080 Speaker 1: this is called a thorn Zitoo object after two astrophysicists 770 00:39:06,080 --> 00:39:09,040 Speaker 1: that predicted it, and we think it's very very rare, 771 00:39:09,080 --> 00:39:10,600 Speaker 1: but there are a few objects out there in the 772 00:39:10,640 --> 00:39:13,879 Speaker 1: sky that sort of have the characteristic signature of one 773 00:39:13,880 --> 00:39:16,439 Speaker 1: of these things, so it might just happen, so maybe 774 00:39:16,440 --> 00:39:19,319 Speaker 1: step me through it. So the super dense neutron star, 775 00:39:19,440 --> 00:39:22,160 Speaker 1: which is not burning but it's super bright, it falls 776 00:39:22,239 --> 00:39:25,000 Speaker 1: into a bigger star that is burning, and so it 777 00:39:25,440 --> 00:39:27,440 Speaker 1: lives inside of it. It does it disrupt it does 778 00:39:27,480 --> 00:39:30,080 Speaker 1: it sort of like stir things up and suck stuff 779 00:39:30,120 --> 00:39:32,800 Speaker 1: out of it. And remember neutron stars not that bright. 780 00:39:32,920 --> 00:39:35,560 Speaker 1: There's no fusion happening in a neutron star, so like 781 00:39:35,600 --> 00:39:37,479 Speaker 1: a white dwarf, it's just sort of like a big 782 00:39:37,520 --> 00:39:40,160 Speaker 1: hot chunk of metal. And we think they mostly glow 783 00:39:40,200 --> 00:39:42,520 Speaker 1: in the X ray at least that's how we study them. 784 00:39:42,680 --> 00:39:45,040 Speaker 1: So what happens is that it orbits in the outside 785 00:39:45,080 --> 00:39:47,800 Speaker 1: part of the star, but eventually it spirals in towards 786 00:39:47,840 --> 00:39:50,719 Speaker 1: the center for the same reason that the neutron star 787 00:39:50,880 --> 00:39:53,799 Speaker 1: like falls into this red giant. Eventually it will fall 788 00:39:53,800 --> 00:39:56,680 Speaker 1: and become like the core and it will suck up 789 00:39:56,719 --> 00:39:59,600 Speaker 1: stuff from that red giant and become a black hole 790 00:40:00,120 --> 00:40:03,439 Speaker 1: and just like eat the entire rest of the star. Well, 791 00:40:03,760 --> 00:40:07,480 Speaker 1: it's like a bad virus kind it's like it comes in. 792 00:40:07,520 --> 00:40:10,040 Speaker 1: It's like an impurity, right, Like the star is happily 793 00:40:10,040 --> 00:40:11,960 Speaker 1: burning along and then this thing comes in and it 794 00:40:12,200 --> 00:40:14,640 Speaker 1: totally disrupts it and takes over it. Yeah, they're like 795 00:40:14,719 --> 00:40:18,000 Speaker 1: eats the star from the inside out. And we've seen 796 00:40:18,000 --> 00:40:20,120 Speaker 1: a bunch of these red giants, and people think that 797 00:40:20,160 --> 00:40:22,520 Speaker 1: you might be able to tell what's happening on the 798 00:40:22,560 --> 00:40:24,759 Speaker 1: inside of the star by looking at what's happening on 799 00:40:24,760 --> 00:40:28,160 Speaker 1: the outside of the star. Like the fraction of various 800 00:40:28,280 --> 00:40:31,360 Speaker 1: kinds of nuclei that appear on the surface depend on 801 00:40:31,400 --> 00:40:33,879 Speaker 1: the temperature of the inside of the star. And if 802 00:40:33,880 --> 00:40:36,160 Speaker 1: you have one of these red super giants with a 803 00:40:36,200 --> 00:40:39,040 Speaker 1: neutron star at its core that's turning into a black hole, 804 00:40:39,160 --> 00:40:41,359 Speaker 1: that would make the star much hotter, so it burn 805 00:40:41,400 --> 00:40:43,600 Speaker 1: a little differently, so it look a little bit different 806 00:40:43,640 --> 00:40:46,400 Speaker 1: on the outside. But it's pretty interesting. Yeah, And you 807 00:40:46,440 --> 00:40:50,040 Speaker 1: can actually see maybe one of these events happening out there, right, 808 00:40:50,120 --> 00:40:51,920 Speaker 1: I mean, the space is so big you probably can 809 00:40:51,920 --> 00:40:53,960 Speaker 1: find an example of it. And there's a sort of 810 00:40:54,000 --> 00:40:56,839 Speaker 1: a cool one that you can see called the necklace nebula, right, Yeah, 811 00:40:56,840 --> 00:40:59,960 Speaker 1: the necklace nebula is this beautiful sort of like glitter 812 00:41:00,040 --> 00:41:03,719 Speaker 1: are of shiny diamonds in the sky like surrounding a 813 00:41:03,800 --> 00:41:07,080 Speaker 1: central object and a stromers think that ten thousand years ago, 814 00:41:07,640 --> 00:41:10,880 Speaker 1: one star expanded sort of like sucked up its neighbor 815 00:41:11,080 --> 00:41:15,359 Speaker 1: companion star, which then continues to sort of orbit inside 816 00:41:15,440 --> 00:41:18,520 Speaker 1: the larger star, which you know, sort of like stirred 817 00:41:18,560 --> 00:41:21,120 Speaker 1: it up like a you know, a spoon in batter. 818 00:41:21,360 --> 00:41:23,200 Speaker 1: If you mix up your spoon too fast, you end 819 00:41:23,239 --> 00:41:25,920 Speaker 1: up like spewing batter outside of the bowl. And so 820 00:41:26,000 --> 00:41:28,680 Speaker 1: this sort of happened to the bigger star. The little 821 00:41:28,719 --> 00:41:30,920 Speaker 1: star inside of it sort of like ruined it and 822 00:41:31,000 --> 00:41:33,160 Speaker 1: spewed bits of it out. And so now what we 823 00:41:33,200 --> 00:41:37,239 Speaker 1: see is this like pattern of basically splashes in the sky. Yeah, 824 00:41:37,400 --> 00:41:39,480 Speaker 1: you can look it up on the internet. The necklace 825 00:41:39,560 --> 00:41:41,680 Speaker 1: nebula and it sort of looks like a necklace, right 826 00:41:41,680 --> 00:41:44,719 Speaker 1: with a shiny diamonds in it. Yeah, exactly. And that's 827 00:41:44,719 --> 00:41:47,759 Speaker 1: what happens when one star totally messes with another star, 828 00:41:47,920 --> 00:41:50,360 Speaker 1: like it stirred it up and spread it out. It 829 00:41:50,440 --> 00:41:53,400 Speaker 1: made beautiful jewelry made blink for all the Hollywood Stars 830 00:41:53,880 --> 00:41:56,600 Speaker 1: universe bling. All right, Well, um, those are some pretty 831 00:41:56,600 --> 00:41:59,240 Speaker 1: cool collisions we can see out there in the universe 832 00:41:59,360 --> 00:42:02,160 Speaker 1: with what at our future, Like, what's going to happen 833 00:42:02,280 --> 00:42:05,160 Speaker 1: to our star, our galaxy. I mean, we talked about 834 00:42:05,160 --> 00:42:07,759 Speaker 1: how it's sort of rare that they probably won't happen 835 00:42:07,800 --> 00:42:11,640 Speaker 1: to us anytime soon. But there's another galaxy coming our way. 836 00:42:11,760 --> 00:42:16,279 Speaker 1: There is another galaxy coming our way, our neighbor, galaxy Andromeda, 837 00:42:16,440 --> 00:42:18,879 Speaker 1: is going to impact the Milky Way in about four 838 00:42:18,920 --> 00:42:22,000 Speaker 1: and a half a billion years. It's coming right for us. 839 00:42:22,480 --> 00:42:24,560 Speaker 1: And people who look up at the sky, you know, 840 00:42:24,600 --> 00:42:26,879 Speaker 1: you're familiar with the Moon, of course, and a bunch 841 00:42:26,880 --> 00:42:29,520 Speaker 1: of stars and maybe even like the splash of the 842 00:42:29,600 --> 00:42:33,160 Speaker 1: Milky Way, but also up there in the sky our galaxies. 843 00:42:33,480 --> 00:42:35,960 Speaker 1: You can see galaxies up there in the sky. The 844 00:42:36,000 --> 00:42:38,560 Speaker 1: problem is that mostly they're very, very dim, so you 845 00:42:38,600 --> 00:42:41,000 Speaker 1: need a telescope to see them. But they're out there, 846 00:42:41,200 --> 00:42:44,400 Speaker 1: and that's sort of like the vast cosmic sweep of 847 00:42:44,440 --> 00:42:46,759 Speaker 1: your view. You can see out there billions of light 848 00:42:46,840 --> 00:42:49,600 Speaker 1: years past our Milky Way. Yeah, and you can see 849 00:42:49,719 --> 00:42:51,680 Speaker 1: a ton of galaxies out there. There are trillions of 850 00:42:51,719 --> 00:42:53,719 Speaker 1: them out there, right, that's right. And mostly they're really 851 00:42:53,760 --> 00:42:56,279 Speaker 1: really distant, and so they're super duper small and not 852 00:42:56,480 --> 00:42:59,759 Speaker 1: very bright. And Dromeda, however, is our neighbor, and so 853 00:42:59,800 --> 00:43:03,640 Speaker 1: it's actually quite near and quite large in the sky. 854 00:43:03,800 --> 00:43:05,480 Speaker 1: You can't see it with the naked eye because it's 855 00:43:05,520 --> 00:43:08,040 Speaker 1: so dim, but if it were brighter, it would appear 856 00:43:08,160 --> 00:43:11,200 Speaker 1: larger in the night sky than the full moon. It's 857 00:43:11,239 --> 00:43:14,720 Speaker 1: like really big and quite close. Interesting, and it's coming 858 00:43:14,840 --> 00:43:17,480 Speaker 1: our way sort of like right, we're on a collision course, 859 00:43:17,520 --> 00:43:20,000 Speaker 1: but we are on a collision course with it exactly. 860 00:43:20,160 --> 00:43:23,200 Speaker 1: So the gravity of all those billions and billions of 861 00:43:23,200 --> 00:43:26,360 Speaker 1: stars are tugging on our billions and billions of stars, 862 00:43:26,440 --> 00:43:29,320 Speaker 1: and eventually we will collide. Because Andromeda in the Milky 863 00:43:29,320 --> 00:43:31,680 Speaker 1: Way are part of this cluster of galaxies we call 864 00:43:31,760 --> 00:43:35,440 Speaker 1: the local cluster, sort of like a loosely bound group 865 00:43:35,520 --> 00:43:38,640 Speaker 1: of clusters. They're held together by each other's gravity and 866 00:43:38,800 --> 00:43:41,720 Speaker 1: sort of swirling around each other. It's all very slow 867 00:43:41,760 --> 00:43:44,400 Speaker 1: motion and takes billions of years for anything interesting to happen. 868 00:43:44,600 --> 00:43:47,160 Speaker 1: But galaxies do collide. And if you look out there 869 00:43:47,160 --> 00:43:49,719 Speaker 1: in the space, we can see so many galaxies that 870 00:43:49,719 --> 00:43:53,799 Speaker 1: there are lots of examples of galaxies colliding, perturbing each other, 871 00:43:54,000 --> 00:43:57,399 Speaker 1: then settling down again into spiral galaxies. And we think, 872 00:43:57,400 --> 00:44:01,000 Speaker 1: for example, the Milky Way has already survived several collisions. 873 00:44:01,320 --> 00:44:03,239 Speaker 1: Really you can see sort of the scars of it, 874 00:44:03,360 --> 00:44:06,240 Speaker 1: or like, are you saying some of these globular clusters 875 00:44:06,280 --> 00:44:09,680 Speaker 1: maybe we're collisions, maybe the globular clusters. But also if 876 00:44:09,719 --> 00:44:11,760 Speaker 1: you look at the shape of the Milky Way, for example, 877 00:44:11,800 --> 00:44:14,640 Speaker 1: it's not flat, like it's not a flat disc. It 878 00:44:14,680 --> 00:44:16,440 Speaker 1: has a bit of a warp to it. And some 879 00:44:16,480 --> 00:44:19,200 Speaker 1: people think that might be because we're still settling down 880 00:44:19,320 --> 00:44:22,560 Speaker 1: from a recent collision or merger with another galaxy. So 881 00:44:22,680 --> 00:44:24,600 Speaker 1: now we're we just went up a level, right when 882 00:44:24,719 --> 00:44:28,000 Speaker 1: we went up from stars colliding to galaxies colliding, and 883 00:44:28,080 --> 00:44:30,200 Speaker 1: so kind of what happens when two galaxies collide, because 884 00:44:30,200 --> 00:44:32,239 Speaker 1: galaxies don't have sort of a structure, right, they're more 885 00:44:32,560 --> 00:44:35,120 Speaker 1: mostly like sort of clouds of stuff. Yeah, there is 886 00:44:35,120 --> 00:44:37,240 Speaker 1: a structure in the sense that there's like a density 887 00:44:37,239 --> 00:44:40,640 Speaker 1: of the core and sometimes a supermassive black hole. Mostly 888 00:44:40,680 --> 00:44:44,200 Speaker 1: they're just big, diffuse clouds of stars and gas and dust. 889 00:44:44,520 --> 00:44:46,800 Speaker 1: And you might imagine that when two galaxies collide it 890 00:44:46,800 --> 00:44:49,640 Speaker 1: would be really dramatic all the stars would explode, etcetera. 891 00:44:49,719 --> 00:44:52,640 Speaker 1: But actually stars are really far apart, and so when 892 00:44:52,719 --> 00:44:56,440 Speaker 1: two galaxies collide, you don't actually get very many collisions, 893 00:44:56,480 --> 00:44:59,279 Speaker 1: maybe just like a few you know, five or ten 894 00:44:59,360 --> 00:45:03,440 Speaker 1: stars actually collide. Mostly it happens sort of slowly and 895 00:45:03,480 --> 00:45:06,920 Speaker 1: they just kind of merge. It's like two crowds walking 896 00:45:06,960 --> 00:45:08,760 Speaker 1: into each other. Right, they just sort of like become 897 00:45:08,840 --> 00:45:13,040 Speaker 1: one bigger crowd. Very few actually, like you know, accidents really, 898 00:45:13,280 --> 00:45:15,600 Speaker 1: so I'm a nott of surprised only five to ten 899 00:45:15,680 --> 00:45:19,880 Speaker 1: collisions of stars would happen, Like, aren't doesn't each galaxy have, 900 00:45:20,239 --> 00:45:22,719 Speaker 1: you know, trillions of stars. Wouldn't that just sort of 901 00:45:22,880 --> 00:45:26,880 Speaker 1: increase exponentially the likelihood of collisions happening, Like, thanks, you 902 00:45:26,880 --> 00:45:29,920 Speaker 1: just got twice as crowded, right, Well, it becomes a 903 00:45:29,960 --> 00:45:33,239 Speaker 1: bigger galaxy, so it's not necessarily twice as crowded, just 904 00:45:33,320 --> 00:45:36,520 Speaker 1: a larger number of stars, like and Drama is already 905 00:45:36,640 --> 00:45:39,920 Speaker 1: much bigger than the Milky Way, probably because it's already 906 00:45:39,960 --> 00:45:43,040 Speaker 1: eaten other galaxies. And so what happens. You just become 907 00:45:43,080 --> 00:45:46,560 Speaker 1: like a bigger galaxy orbiting like a common center of mass. 908 00:45:46,560 --> 00:45:49,160 Speaker 1: So you don't actually get that many star collisions. You 909 00:45:49,200 --> 00:45:51,120 Speaker 1: just get this sort of like new shape. It takes 910 00:45:51,160 --> 00:45:53,480 Speaker 1: like sometimes a billion years or so to settle down 911 00:45:53,480 --> 00:45:55,799 Speaker 1: into a steady path, but the stars are pretty far 912 00:45:55,840 --> 00:45:58,120 Speaker 1: apart from each other. Wouldn't they merge though, wouldn't Like 913 00:45:58,160 --> 00:46:00,480 Speaker 1: the dramatic cloud sort of merged with our cloud and 914 00:46:00,520 --> 00:46:03,480 Speaker 1: suddenly things are more dense. Well, they definitely do merge, 915 00:46:03,520 --> 00:46:06,800 Speaker 1: but because of the rotation speed, things don't all collapse 916 00:46:06,800 --> 00:46:08,680 Speaker 1: into the center. So you get a lot of stars 917 00:46:08,680 --> 00:46:11,200 Speaker 1: that are still far out from the center that are 918 00:46:11,200 --> 00:46:13,920 Speaker 1: moving really really fast. Right. The reason that the galaxy 919 00:46:13,960 --> 00:46:16,880 Speaker 1: doesn't collapse into like a super dense blob of stars 920 00:46:17,239 --> 00:46:19,720 Speaker 1: is because all these stars are moving pretty fast around 921 00:46:19,719 --> 00:46:22,359 Speaker 1: the center, the same reason the Earth doesn't fall into 922 00:46:22,360 --> 00:46:25,680 Speaker 1: the Sun immediately. So when these galaxies collide, they keep 923 00:46:25,760 --> 00:46:28,000 Speaker 1: that spin and they keep going around the center and 924 00:46:28,040 --> 00:46:30,480 Speaker 1: sometimes even faster because now you have like the relative 925 00:46:30,480 --> 00:46:33,600 Speaker 1: angular velocity of the two galaxies, and so they don't 926 00:46:33,600 --> 00:46:36,000 Speaker 1: all just collapse into a dense blob. It can become 927 00:46:36,040 --> 00:46:39,640 Speaker 1: like a really huge, spread out new galaxy. Right Yeah. 928 00:46:39,800 --> 00:46:42,920 Speaker 1: But also like the collision would disrupt the structure of 929 00:46:42,960 --> 00:46:46,080 Speaker 1: both galaxies, right, just like if you have two stars 930 00:46:46,239 --> 00:46:48,960 Speaker 1: or two solar systems colliding into each other, like it 931 00:46:48,960 --> 00:46:51,480 Speaker 1: would be chaos kind of, right, Like everything would be 932 00:46:51,520 --> 00:46:53,640 Speaker 1: thrown out of balance, it would, But those things are 933 00:46:53,640 --> 00:46:55,840 Speaker 1: typically much more separated like a solar system is a 934 00:46:55,920 --> 00:46:59,240 Speaker 1: very dense object compared to a galaxy. The distances between 935 00:46:59,280 --> 00:47:02,520 Speaker 1: stars as much much bigger relatively speaking than the distances 936 00:47:02,520 --> 00:47:05,759 Speaker 1: between planets. But also galaxies of other stuff. And then 937 00:47:05,840 --> 00:47:09,600 Speaker 1: they're not just stars, right. Galaxies also have huge clouds 938 00:47:09,600 --> 00:47:13,080 Speaker 1: of gas and dust places that new stars can form. 939 00:47:13,160 --> 00:47:16,040 Speaker 1: And when two galaxies collide, what does happen is that 940 00:47:16,080 --> 00:47:18,799 Speaker 1: those clouds of gas and dust collide. Those are not 941 00:47:18,840 --> 00:47:22,960 Speaker 1: like diffuse, those are really thick clouds relatively speaking, So 942 00:47:23,280 --> 00:47:26,000 Speaker 1: that triggers a lot of activity because that triggers like 943 00:47:26,160 --> 00:47:29,720 Speaker 1: new star formation. You shoot one big cloud or another 944 00:47:29,719 --> 00:47:33,279 Speaker 1: big cloud, and those shock waves can trigger the gravitational 945 00:47:33,360 --> 00:47:37,040 Speaker 1: runaway effect that leads to new stars being formed. Wow. 946 00:47:37,560 --> 00:47:40,480 Speaker 1: So mostly we should be looking at the collision of 947 00:47:40,520 --> 00:47:43,320 Speaker 1: gas and dust because then that makes new stars exactly. 948 00:47:43,360 --> 00:47:46,279 Speaker 1: Mostly what happens when galaxies collide is the collision of 949 00:47:46,320 --> 00:47:48,839 Speaker 1: the gas and dust that makes new stars. And so 950 00:47:48,880 --> 00:47:51,400 Speaker 1: we'll have some stars from the Milky Way, some stars 951 00:47:51,400 --> 00:47:54,239 Speaker 1: from and Drameda, and then some brand new stars from 952 00:47:54,239 --> 00:47:58,040 Speaker 1: this new galaxy. New neighbors are moving in, hopefully not 953 00:47:58,160 --> 00:48:00,759 Speaker 1: too close, but that's if we survive long enough to 954 00:48:00,840 --> 00:48:03,080 Speaker 1: even see that collision. Yeah, I guess four point five 955 00:48:03,120 --> 00:48:05,200 Speaker 1: billion years is a long time, right, Like by then 956 00:48:05,280 --> 00:48:07,839 Speaker 1: the we might not even be on Earth. The Sun 957 00:48:07,920 --> 00:48:10,600 Speaker 1: is gonna pete route ride around then, and so we 958 00:48:10,719 --> 00:48:13,160 Speaker 1: got a few billion years to make a plan for, 959 00:48:13,200 --> 00:48:15,000 Speaker 1: you know, get to a new home because the Sun 960 00:48:15,040 --> 00:48:17,319 Speaker 1: will no longer be a happy place to orbit in 961 00:48:17,400 --> 00:48:20,040 Speaker 1: five billion years. Sounds like a good time to hop 962 00:48:20,120 --> 00:48:24,040 Speaker 1: over to our new galaxy jump ship. That's right, there's 963 00:48:24,040 --> 00:48:27,160 Speaker 1: lots of empty apartments over there, hopefully may or maybe 964 00:48:27,239 --> 00:48:29,880 Speaker 1: stored there. Maybe they're crowded too, but there's some dangerous 965 00:48:29,920 --> 00:48:33,279 Speaker 1: coming well before four billion years have passed. You mean, 966 00:48:33,360 --> 00:48:35,960 Speaker 1: not from Andromeda. Yeah, we talked about how it's very 967 00:48:36,040 --> 00:48:38,840 Speaker 1: unlikely for our star to collide with another star, but 968 00:48:38,880 --> 00:48:41,880 Speaker 1: astronomers have looked all the stars nearby and tried to 969 00:48:41,920 --> 00:48:44,960 Speaker 1: calculate like when there might be a near miss. And 970 00:48:45,000 --> 00:48:49,359 Speaker 1: there is another star it's called Glease, and astronomers think 971 00:48:49,400 --> 00:48:51,719 Speaker 1: that in a million years it's going to pass within 972 00:48:52,160 --> 00:48:55,480 Speaker 1: one fifteen of a light year of our solar system. 973 00:48:55,680 --> 00:48:58,719 Speaker 1: So not a direct collision, but like pretty close to 974 00:48:58,719 --> 00:49:01,360 Speaker 1: our neighborhood and thing, So what do you mean we 975 00:49:01,440 --> 00:49:03,480 Speaker 1: think like we we can see all the stars in 976 00:49:03,520 --> 00:49:06,720 Speaker 1: our neighborhood and we can probably track them. What where's 977 00:49:06,719 --> 00:49:09,120 Speaker 1: the uncertainty? I was just trying to make people feel better. Yeah, 978 00:49:09,120 --> 00:49:15,680 Speaker 1: it's pretty certain it. I see it's coming. It's coming exactly. 979 00:49:16,440 --> 00:49:18,759 Speaker 1: So at one fifteenth of a idea, how much is 980 00:49:18,800 --> 00:49:22,160 Speaker 1: that in kilometers or a US? So that's about four 981 00:49:22,320 --> 00:49:25,240 Speaker 1: thousand a US. So it's well within our solar system 982 00:49:25,239 --> 00:49:27,319 Speaker 1: if you include, for example, the Orc Cloud, which goes 983 00:49:27,360 --> 00:49:30,239 Speaker 1: out like tens of thousands of a use, but it's 984 00:49:30,320 --> 00:49:32,840 Speaker 1: much further out than like the most distant planets, but 985 00:49:33,000 --> 00:49:35,959 Speaker 1: plenty close to disturb the Orc Cloud. It's gonna pass 986 00:49:36,120 --> 00:49:38,719 Speaker 1: right through the Orc Cloud. It's going to create crazy 987 00:49:38,840 --> 00:49:41,520 Speaker 1: showers of comments. So it is we are sort of 988 00:49:41,520 --> 00:49:44,000 Speaker 1: technically going to collide our solar system if you include 989 00:49:44,000 --> 00:49:46,080 Speaker 1: the Orc Cloud and all those things out there in 990 00:49:46,080 --> 00:49:49,160 Speaker 1: the fringes, it is going to collide with this other star. Yeah, 991 00:49:49,200 --> 00:49:51,600 Speaker 1: and you know, our Orc cloud is probably always getting 992 00:49:51,640 --> 00:49:54,560 Speaker 1: little gravitational tugs from close by stars and that might 993 00:49:54,600 --> 00:49:56,880 Speaker 1: be what's driving comments. But yeah, this star is going 994 00:49:56,960 --> 00:49:59,640 Speaker 1: to come smash right into our Orc Cloud, and it's 995 00:49:59,640 --> 00:50:02,239 Speaker 1: going to be a crazy meteor shower. I hope that 996 00:50:02,280 --> 00:50:05,160 Speaker 1: we survive it. Wow, well again, we just we need 997 00:50:05,440 --> 00:50:08,319 Speaker 1: a pretty big umbrella. And it's probably coming with its 998 00:50:08,360 --> 00:50:11,439 Speaker 1: own or cloud, right like, every solar system probably has 999 00:50:11,480 --> 00:50:13,800 Speaker 1: a collection of these icy objects. So when our I 1000 00:50:14,080 --> 00:50:16,840 Speaker 1: objects glide with its icy objects, who knows what's going 1001 00:50:16,880 --> 00:50:19,960 Speaker 1: to happen? Right like, our solar systems might mix. So 1002 00:50:20,160 --> 00:50:22,560 Speaker 1: do scientists know what's gonna happen? Are we're gonna emerge 1003 00:50:22,560 --> 00:50:24,400 Speaker 1: with it? It is just going to be a drive by. 1004 00:50:24,520 --> 00:50:27,560 Speaker 1: It's gonna start orbiting our solar system. What's gonna happen, Well, 1005 00:50:27,560 --> 00:50:29,600 Speaker 1: it's going to pass through fast enough that it's not 1006 00:50:29,600 --> 00:50:32,160 Speaker 1: going to form a binary star system, but it's very 1007 00:50:32,239 --> 00:50:34,680 Speaker 1: likely to perturb the orbits of the planets and to 1008 00:50:34,760 --> 00:50:38,160 Speaker 1: cause a lot of commentary showers. Exactly what happens depends 1009 00:50:38,160 --> 00:50:40,879 Speaker 1: on exactly where the planets are when it comes by, 1010 00:50:40,920 --> 00:50:43,400 Speaker 1: and we don't have enough certainty to make that prediction. 1011 00:50:43,600 --> 00:50:45,600 Speaker 1: But we will probably see it in the night sky though, 1012 00:50:45,719 --> 00:50:48,160 Speaker 1: right like we'll see the star swinging by. Yeah, it's 1013 00:50:48,160 --> 00:50:50,960 Speaker 1: gonna be brighter than the planet Venus, and you'll be 1014 00:50:50,960 --> 00:50:53,480 Speaker 1: able to see it during the day, So you know, 1015 00:50:53,520 --> 00:50:56,840 Speaker 1: put a notification in your calendar, Siri, set a reminder 1016 00:50:56,880 --> 00:50:59,879 Speaker 1: for one million years from today, look for this star, 1017 00:51:00,360 --> 00:51:05,160 Speaker 1: look outside and bring an umbrella. All right, well, that 1018 00:51:05,280 --> 00:51:08,839 Speaker 1: might be maybe the closest to a star collision our 1019 00:51:08,960 --> 00:51:11,640 Speaker 1: sun will ever get right, I mean, that's that's about it, right, 1020 00:51:11,800 --> 00:51:14,520 Speaker 1: let's hope. What do you mean, could something unexpected happen? 1021 00:51:14,680 --> 00:51:17,280 Speaker 1: I don't want a collision even closer than that. Anything 1022 00:51:17,280 --> 00:51:20,520 Speaker 1: close to that is guaranteed to be a cataclysm for humanity. 1023 00:51:21,200 --> 00:51:23,319 Speaker 1: But you're saying that's the closest we can expect, at 1024 00:51:23,360 --> 00:51:25,160 Speaker 1: least in the next you know, a few billion years, 1025 00:51:25,200 --> 00:51:28,360 Speaker 1: a few million years. Yes, all right, Well, I guess 1026 00:51:28,360 --> 00:51:31,080 Speaker 1: it's a pretty wild and crazy universe. You know. Collisions 1027 00:51:31,080 --> 00:51:33,960 Speaker 1: do happen. Stars do collide. Even though there's a lot 1028 00:51:33,960 --> 00:51:36,160 Speaker 1: of space out there, and there are there's a lot 1029 00:51:36,239 --> 00:51:39,000 Speaker 1: of space between stars. It does happen because it's a 1030 00:51:39,120 --> 00:51:41,440 Speaker 1: it's a big universe. Yeah. We are in a tiny 1031 00:51:41,520 --> 00:51:45,880 Speaker 1: little cosmic road floating on a huge, crazy chaotic ocean, 1032 00:51:46,120 --> 00:51:50,240 Speaker 1: and it seems stable only because it's moving so slowly. Yeah, 1033 00:51:50,280 --> 00:51:53,080 Speaker 1: so make sure you bring an umbrella, were a helmet 1034 00:51:53,120 --> 00:51:56,200 Speaker 1: when you jump into the stellar mosh pit of the 1035 00:51:56,360 --> 00:51:59,040 Speaker 1: universe and hope for the best and keep an eye out. 1036 00:51:59,040 --> 00:52:01,279 Speaker 1: I guess well, maybe we'll bump into the stellar version 1037 00:52:01,360 --> 00:52:03,520 Speaker 1: of Brad Pitt at the grocery store and just don't 1038 00:52:03,560 --> 00:52:06,640 Speaker 1: steal his cookies. That might anger Angelina Julian and then 1039 00:52:06,640 --> 00:52:09,480 Speaker 1: you'll have two stars, you know, colliding with you. Well, 1040 00:52:09,480 --> 00:52:11,600 Speaker 1: we hope you enjoyed that. Thanks for joining us, see 1041 00:52:11,640 --> 00:52:21,760 Speaker 1: you next time. Thanks for listening, and remember that Daniel 1042 00:52:21,800 --> 00:52:24,319 Speaker 1: and Jorge Explain the Universe is a production of I 1043 00:52:24,560 --> 00:52:27,960 Speaker 1: Heart Radio or more podcast from my heart Radio. Visit 1044 00:52:28,000 --> 00:52:31,520 Speaker 1: the I heart Radio app, Apple Podcasts, or wherever you 1045 00:52:31,600 --> 00:52:33,120 Speaker 1: listen to your favorite shows.