WEBVTT - Relativistic beaming 0:00:03.640 --> 0:00:06.920 Hey, extraordinaries. Quick note for today's episode, I want to 0:00:06.960 --> 0:00:10.320 let you know about my new book, To Aliens Speak Physics. 0:00:10.600 --> 0:00:13.120 It's all about whether or not we can use physics 0:00:13.119 --> 0:00:16.720 as a universal language to communicate with aliens, or whether 0:00:16.760 --> 0:00:20.000 physics is more human than many people imagine. And the 0:00:20.000 --> 0:00:23.720 book features cute cartoons of aliens from my friend Andy Warner. 0:00:23.920 --> 0:00:26.400 If you've enjoyed my science outreach and wondered how you 0:00:26.440 --> 0:00:28.960 could support me, this is how The book is out 0:00:28.960 --> 0:00:30.920 in November fourth. Look for the link on the book 0:00:30.960 --> 0:00:43.760 website www dot alienspeakphysics dot com. Okay, on to today's episode. 0:00:44.920 --> 0:00:47.959 Whenever we look out into the universe, we see something 0:00:48.080 --> 0:00:52.360 new that astonishes us, something beyond our wildest imaginings of 0:00:52.400 --> 0:00:55.800 what the universe could do. It's a rich tapestry of 0:00:55.880 --> 0:00:59.640 extreme physics, and yet all of it is described by 0:00:59.680 --> 0:01:03.040 physics deep down. The mechanisms that create black holes, or 0:01:03.040 --> 0:01:06.760 collide galaxies or explode stars are rooted in the basic 0:01:06.840 --> 0:01:10.399 principles of physics, and so far we've been able to 0:01:10.400 --> 0:01:13.840 come up with explanations for how these incredible events occur 0:01:14.200 --> 0:01:18.839 and how the universe is vast and beautiful cosmos is shaped. Today, 0:01:18.840 --> 0:01:20.960 we're going to dig into the physics that underlies one 0:01:21.000 --> 0:01:24.800 of the most dramatic and literally brilliant phenomena in space, 0:01:25.280 --> 0:01:31.520 astrophysical jets. Welcome to Daniel and Kelly's extraordinary, brilliant universe. 0:01:44.760 --> 0:01:45.120 Hello. 0:01:45.160 --> 0:01:46.080 I'm Kelly Waidersmith. 0:01:46.080 --> 0:01:49.720 I study parasites and space, and before looking at today's outline, 0:01:49.760 --> 0:01:54.160 I didn't know that astrophysical jets was a phrase that's 0:01:54.160 --> 0:01:54.600 worth it. 0:01:54.960 --> 0:01:58.080 Hi, I'm Daniel. I'm a particle physicist, and if I 0:01:58.120 --> 0:02:01.240 had a baseball team, I might call them the astrophysical Jets. 0:02:01.600 --> 0:02:03.760 Oh, is that because your brain is fixating on the 0:02:03.800 --> 0:02:04.559 astros part? 0:02:06.480 --> 0:02:08.000 It just sounds like a team that would score a 0:02:08.040 --> 0:02:08.560 lot of runs. 0:02:08.720 --> 0:02:11.600 Yeah, yeah, no and throw their balls really fast. I think. 0:02:12.919 --> 0:02:14.960 So, when I was looking through the outline today, it 0:02:14.960 --> 0:02:18.000 occurred to me that this doesn't feel like it's in 0:02:18.080 --> 0:02:20.840 your main area of research, and so I was wondering 0:02:20.880 --> 0:02:23.840 if you could tell us, like, when you are researching 0:02:23.880 --> 0:02:27.160 something that you don't have knowledge of, like right at 0:02:27.160 --> 0:02:31.000 your fingertips, what is your process like for preparing our outline? 0:02:31.200 --> 0:02:34.000 Yeah, well, that's fascinating because this actually is sort of 0:02:34.080 --> 0:02:36.799 right on the edge of my area of research. I'm 0:02:36.840 --> 0:02:39.680 sort of card carrying particle physicists, which means that most 0:02:39.720 --> 0:02:42.200 of my career is like, smash particles together at the 0:02:42.280 --> 0:02:44.480 large had drunk collider, see what new kind of stuff 0:02:44.520 --> 0:02:47.440 comes out. But it's always been super interested in space, 0:02:47.480 --> 0:02:50.480 and like many people, I got into it because of astronomy. 0:02:51.000 --> 0:02:53.680 But then I kind of discovered like astronomy is mostly 0:02:53.760 --> 0:02:55.920 standing around in the cold looking at fuzzy things through 0:02:55.960 --> 0:02:59.640 a telescope, and that wasn't as exciting to me. Apologies 0:02:59.680 --> 0:03:01.320 to us. I mean, there's out there who love that 0:03:01.360 --> 0:03:03.720 and thank you for doing it, but it wasn't for me. 0:03:04.240 --> 0:03:07.680 But later in my career I got reinterested in astrophysics, 0:03:08.040 --> 0:03:10.520 which isn't looking through a telescope, but it's like trying 0:03:10.520 --> 0:03:13.280 to understand the physics behind what's going on out there, 0:03:13.320 --> 0:03:15.440 like how does the star work, et cetera. So the 0:03:15.480 --> 0:03:18.680 last few years I've actually written some papers on the 0:03:18.720 --> 0:03:23.360 centers of galaxies and neutron stars and supernova and stuff 0:03:23.400 --> 0:03:25.960 like this, but it is a little bit far from 0:03:26.000 --> 0:03:28.400 my core area of expertise. So it means reading a 0:03:28.440 --> 0:03:28.799 lot of. 0:03:28.720 --> 0:03:32.799 Papers, got it. How many are you reading. 0:03:34.320 --> 0:03:36.600 All of the papers all of them. 0:03:36.640 --> 0:03:37.160 Wow. 0:03:37.640 --> 0:03:39.520 I mean what I try to do is find a 0:03:39.560 --> 0:03:42.400 review in that area, like, find somebody who knows the fields, 0:03:42.400 --> 0:03:45.920 who's written like a broad perspective, read that really carefully, 0:03:45.960 --> 0:03:48.320 and then read a bunch of the papers it references 0:03:48.640 --> 0:03:51.240 to make sure I know what's being summarized and what's 0:03:51.280 --> 0:03:53.720 actually going on, and what's the sort of the lore 0:03:54.480 --> 0:03:55.920 all this kind of stuff. But it's a lot of 0:03:55.960 --> 0:03:58.600 work to try to really understand a new field well 0:03:58.720 --> 0:04:02.040 enough to try to contribute something to it. And you know, 0:04:02.360 --> 0:04:04.240 I think you were asking though about like if you 0:04:04.240 --> 0:04:06.800 want to talk about something on the podcast, not necessarily 0:04:06.800 --> 0:04:09.200 like write a bunch of papers about it. But I 0:04:09.200 --> 0:04:11.520 finally it's kind of similar to talk about something on 0:04:11.560 --> 0:04:14.040 the podcast. You got to understand it really well because 0:04:14.280 --> 0:04:16.960 my co host is really smart and asks hard questions, 0:04:17.440 --> 0:04:19.400 and if I want to explain things correctly in a 0:04:19.400 --> 0:04:21.800 way that actually clicks in people's minds, I got to 0:04:21.839 --> 0:04:23.840 have it all up in my brain. So yeah, it 0:04:23.920 --> 0:04:26.839 means reading a lot of papers when it's not my area. 0:04:27.000 --> 0:04:28.120 Is that your experience? Also? 0:04:28.279 --> 0:04:28.479 Yeah? 0:04:28.520 --> 0:04:31.040 Yeah, when I'm working on my outline, I'm always asking 0:04:31.040 --> 0:04:36.200 myself wwda, which is what will Daniel ask, trying to 0:04:36.240 --> 0:04:38.960 figure out, like what other things do I need to 0:04:39.000 --> 0:04:40.760 research that I am prepared for whatever? 0:04:40.839 --> 0:04:44.400 Daniel asks, Yeah, I feel like everybody in my life 0:04:44.440 --> 0:04:46.200 who I get to know, I have sort of like 0:04:46.240 --> 0:04:48.320 a mini version of them in my head, like a 0:04:48.360 --> 0:04:51.640 little model of them which constantly gets you know, improved 0:04:51.680 --> 0:04:54.320 and updated and of course the most interesting people, it's 0:04:54.360 --> 0:04:56.839 never actually correct, which is why they can wonderfully surprise me. 0:04:57.320 --> 0:04:59.680 But I feel like that's a big part of understanding 0:04:59.720 --> 0:05:02.080 who's somebody is. It's like comparing them to like the 0:05:02.120 --> 0:05:03.880 little model you have of who they are and what 0:05:03.920 --> 0:05:06.679 they might say and how they might react. It's super fun. 0:05:06.800 --> 0:05:08.520 Do the models in here, and then we should change 0:05:08.520 --> 0:05:11.160 subjects back to what we meant to talk about today. 0:05:11.200 --> 0:05:12.680 But do the models in your head? 0:05:12.760 --> 0:05:16.000 Like, are they like miniature people that you see or 0:05:16.000 --> 0:05:18.799 are you just imagining their personalities without their bodies? 0:05:19.080 --> 0:05:20.880 Like what do you imagine? 0:05:21.279 --> 0:05:22.880 Are they in the room with me right now? 0:05:23.240 --> 0:05:23.400 Right? 0:05:23.520 --> 0:05:23.560 So? 0:05:24.279 --> 0:05:27.040 I'm not schizophrenic, I'm pretty sure. No, it's just like you, 0:05:27.160 --> 0:05:29.400 I just asked myself, you know, what would my kids 0:05:29.440 --> 0:05:31.760 say in this situation? Or how would my wife react 0:05:31.800 --> 0:05:35.279 to having this for dinner? Or what would Kelly ask 0:05:35.360 --> 0:05:38.159 me if I said X y Z. You know, I 0:05:38.160 --> 0:05:40.960 think they're just useful for trying to understand who somebody is. 0:05:41.200 --> 0:05:43.360 But I also think it's helpful for understanding yourself because 0:05:43.400 --> 0:05:45.440 you end up building also a model of yourself and 0:05:45.480 --> 0:05:48.239 turning the inwards and anyway, I have my own Bonker's 0:05:48.279 --> 0:05:51.000 theory of consciousness, but that's not what today's episode is about. 0:05:52.040 --> 0:05:55.239 So when you sent me the outline for relativistic beaming, 0:05:55.400 --> 0:05:59.400 I was like, I just have zero clue what this means. 0:06:00.000 --> 0:06:02.960 We'll give us, like some background what we should expect 0:06:02.960 --> 0:06:03.640 in this episode. 0:06:03.880 --> 0:06:06.799 Yeah, this episode is about how the universe is constantly 0:06:06.839 --> 0:06:09.719 surprising us. How every time we look out into space 0:06:10.000 --> 0:06:13.679 we see something new and weird, something that doesn't quite 0:06:13.680 --> 0:06:16.880 make sense. And yet if we apply our knowledge of physics, 0:06:16.880 --> 0:06:19.599 it turns out we can crack it. We can make 0:06:19.640 --> 0:06:22.640 sense that we can explain why it's happening, and often 0:06:22.640 --> 0:06:26.240 it gives us an incredible view of what's going on 0:06:26.560 --> 0:06:29.840 in extreme situations, you know, the cores of galaxies, when 0:06:29.880 --> 0:06:32.640 things are really hot and dense and fast. But it 0:06:32.680 --> 0:06:35.480 requires us to put together a lot of little pieces 0:06:35.520 --> 0:06:40.360 of physics. Gravity electromagnetism, even special relativity, in order to 0:06:40.400 --> 0:06:43.240 explain what we see out there in the universe. And 0:06:43.360 --> 0:06:46.520 so today's episode is a story of like several decades, 0:06:46.560 --> 0:06:49.680 almost a century, of trying to understand some stuff we 0:06:49.720 --> 0:06:52.479 see out in space and finally putting it together. And 0:06:52.520 --> 0:06:56.400 the last piece of that is a process called relativistic beaming. 0:06:56.880 --> 0:06:58.680 And I had a bunch of listeners write to me 0:06:58.720 --> 0:07:02.040 and ask me about these astrophysical jets that are omitted 0:07:02.040 --> 0:07:04.440 from the centers of galaxies, and so I thought, let's 0:07:04.440 --> 0:07:07.799 do a deep dive into all the physics that makes 0:07:07.839 --> 0:07:11.440 those happen, especially that last bit, which I've never heard 0:07:11.440 --> 0:07:14.400 anybody cover with a popular treatment. So that was the 0:07:14.440 --> 0:07:16.120 motivation for today's episode. 0:07:16.320 --> 0:07:16.680 Awesome. 0:07:16.840 --> 0:07:19.720 I'm excited about today's episode because I love those moments where, like, 0:07:20.160 --> 0:07:23.120 you've studied a bunch of different topics that don't necessarily 0:07:23.160 --> 0:07:25.360 seem connected, but they turn out to be the building 0:07:25.400 --> 0:07:29.160 blocks that you need to understand something completely different that 0:07:29.200 --> 0:07:30.960 you probably wouldn't have been able to understand if you 0:07:31.000 --> 0:07:33.520 hadn't done all of that background sort of foundational work 0:07:33.520 --> 0:07:34.080 ahead of time. 0:07:34.200 --> 0:07:36.520 Exactly, So let's learn, all. 0:07:36.560 --> 0:07:39.200 Right, And so relativistic beaming is the last piece of it, 0:07:39.240 --> 0:07:42.080 but maybe the least well known. So I decided to 0:07:42.120 --> 0:07:44.160 go out there and ask our audience if they knew 0:07:44.200 --> 0:07:47.800 anything about relativistic beaming to help us calibrate. If you 0:07:48.200 --> 0:07:51.000 would like to participate for our future episodes, please don't 0:07:51.000 --> 0:07:55.080 be shy. Write to us questions at Danielankelly dot org. 0:07:55.440 --> 0:07:58.840 In the meantime, ask yourself, do you know what relativistic 0:07:58.960 --> 0:08:02.280 beaming is? Here's what our listeners had to say. 0:08:02.680 --> 0:08:03.560 Relativistic beaming. 0:08:03.600 --> 0:08:06.320 I think that's when Chapman from the Yankees beams you 0:08:06.480 --> 0:08:10.440 in the head by accident, and if that happens with 0:08:10.560 --> 0:08:12.880 one of his fastballs, and then when that happens, time 0:08:12.920 --> 0:08:15.080 will definitely go slower for you. 0:08:15.880 --> 0:08:19.360 So relativistic relativistic beaming, well. 0:08:19.200 --> 0:08:20.880 I can't remember off the top of my head. I 0:08:20.920 --> 0:08:24.520 think it was to do with synchotrons. When electrons are 0:08:25.080 --> 0:08:28.320 going near the speed of light and go around a corner. 0:08:28.640 --> 0:08:32.120 The radiation they release very is in a very tightly 0:08:32.120 --> 0:08:35.080 controlled spatial beam because of relativistic effects. 0:08:35.520 --> 0:08:39.840 Relativistic beaming is the ability of a thought to enter 0:08:39.920 --> 0:08:43.040 my mind and then instantly disappear as soon as I 0:08:43.120 --> 0:08:45.840 try to act on it. But in physics, maybe it's 0:08:45.880 --> 0:08:49.760 something to do with moving near massless particles near the 0:08:49.760 --> 0:08:52.320 speed of light and taking advantage of some of the 0:08:52.360 --> 0:08:54.720 relativistic changes that occur as a result. 0:08:55.240 --> 0:08:57.199 I think my favorite answer, I mean, they were all great, 0:08:57.320 --> 0:08:59.679 but was how a thought enters my mind and then 0:08:59.760 --> 0:09:03.880 it's disappears. Relativistic beaming in that sense happens to me 0:09:04.040 --> 0:09:05.600 like fifty times a day lately. 0:09:05.800 --> 0:09:07.199 You have that experience where you have an idea and 0:09:07.240 --> 0:09:08.960 then you try to write it down before it leaves 0:09:08.960 --> 0:09:12.000 your brain, and sometimes it's like no pencil or paper, 0:09:12.160 --> 0:09:13.880 you can't get to your phone, and you're like, oh, no, 0:09:13.960 --> 0:09:14.960 it's gonna go away. 0:09:15.080 --> 0:09:16.920 Yeah, it does, it go away, because it does for 0:09:17.000 --> 0:09:19.400 me a lot of the time. Or are you just scared? 0:09:19.440 --> 0:09:19.920 But it stays? 0:09:20.040 --> 0:09:22.680 We does, okay, No, And then sometimes I have like 0:09:22.960 --> 0:09:25.760 the remnants of the idea. I'm like, I remember feeling 0:09:25.800 --> 0:09:27.960 this way about it and it was something about that 0:09:28.160 --> 0:09:29.080 and what was it? 0:09:29.120 --> 0:09:32.079 And man, yep, no, I all think to myself, don't 0:09:32.080 --> 0:09:34.560 get distracted, don't get distracted while I'm looking for the pencil, 0:09:34.600 --> 0:09:37.000 and then I always think about, like, oh, did we 0:09:37.000 --> 0:09:39.120 make it as lunch this morning? And then it's gone 0:09:39.240 --> 0:09:42.760 and anyway, Okay, so the thought that we do not 0:09:42.840 --> 0:09:45.600 want to forget is what is relativistic beaming. 0:09:45.720 --> 0:09:48.880 That's right. And the story starts with the things shooting 0:09:48.920 --> 0:09:53.160 out of the centers of galaxies. These things called astrophysical jets. 0:09:53.679 --> 0:09:55.960 And if you have a mental image of a galaxy, 0:09:56.040 --> 0:09:58.800 you're probably imagining something like a disc. You've got a 0:09:58.840 --> 0:10:02.200 bunch of stars a swirl together, and that's what the 0:10:02.240 --> 0:10:04.600 Milky Way looks like, and that's what Andromeda looks like. 0:10:05.000 --> 0:10:09.160 But there's another really important feature of galaxies that's not 0:10:09.200 --> 0:10:12.320 always visible to the naked eye, and these are the 0:10:12.440 --> 0:10:15.280 jets that shoot up and down from the poles of 0:10:15.320 --> 0:10:17.920 the galaxy, out of the center. So instead of just 0:10:18.000 --> 0:10:21.160 imagining a disk, imagine a huge beam of light beaming 0:10:21.240 --> 0:10:24.200 up and down relative to the plane of the disk. 0:10:24.559 --> 0:10:26.320 These are astrophysical jets. 0:10:26.679 --> 0:10:26.959 Okay. 0:10:26.960 --> 0:10:29.080 And so the jet is made of light. And just 0:10:29.120 --> 0:10:32.280 so I make sure i'm picturing thing because you said photons, right. 0:10:32.120 --> 0:10:34.439 Well, the jet has light in it. They are bright, 0:10:34.559 --> 0:10:37.160 but they're actually not just made of light. They're mostly 0:10:37.280 --> 0:10:41.439 plasma so they're like high speed particles. There's electrons, there's protons, 0:10:41.520 --> 0:10:43.199 and there are photons as well. 0:10:43.360 --> 0:10:45.640 Wow, okay, so I just want to make sure that 0:10:45.679 --> 0:10:47.800 I've got my image of a galaxy correct. So at 0:10:47.800 --> 0:10:50.120 the center of our solar system there's the Sun, but 0:10:50.200 --> 0:10:53.240 at the center of a galaxy there isn't necessarily some 0:10:53.440 --> 0:10:55.920 big thing. It's just what is at the center of 0:10:55.920 --> 0:10:58.000 a galaxy. We talked about it maybe being a black hole, 0:10:58.320 --> 0:10:59.640 but we don't really know right well. 0:10:59.640 --> 0:11:01.440 There are lot of questions about what's at the center 0:11:01.480 --> 0:11:03.480 of the galaxy because it's hard to see it's so 0:11:03.720 --> 0:11:06.280 dense there. You know, I think a lot of people 0:11:06.320 --> 0:11:08.200 have the image of a galaxy as like just a 0:11:08.200 --> 0:11:12.200 bunch of stars sprinkled around, But there's a big density variation, 0:11:12.320 --> 0:11:14.920 Like the center of the galaxy is much denser than 0:11:14.960 --> 0:11:17.599 the outskirts. It's sort of like, you know, there's Manhattan 0:11:17.960 --> 0:11:20.319 and then there's the suburbs, and then there's the excerbs, 0:11:20.360 --> 0:11:22.200 and we live kind of in the suburbs. It's not 0:11:22.440 --> 0:11:25.440 very dense, but it's not as rural as it is 0:11:25.720 --> 0:11:28.439 further out in the galaxy. But near the center there's 0:11:28.480 --> 0:11:30.440 a lot of stars and there's a lot of gas 0:11:30.440 --> 0:11:33.040 and dust, so it is difficult to study the center 0:11:33.080 --> 0:11:35.280 of the galaxy. But we do know a lot about 0:11:35.280 --> 0:11:38.080 the centers of the galaxies also by looking at other galaxies, 0:11:38.559 --> 0:11:41.920 and so far, every galaxy we've studied has a super 0:11:41.960 --> 0:11:44.480 massive black hole at its center, with a couple of 0:11:44.520 --> 0:11:47.320 exceptions in cases where we're like pretty sure the super 0:11:47.360 --> 0:11:49.840 massive black hole has been ejected by like a recent 0:11:49.880 --> 0:11:50.840 collision or something. 0:11:50.960 --> 0:11:53.240 You can eject a super massive black hole. 0:11:53.840 --> 0:11:56.040 We've probably talked about this on a prior episode and 0:11:56.040 --> 0:11:58.720 my bad memory is why life is so endlessly surprising 0:11:58.720 --> 0:11:58.880 to me? 0:11:59.040 --> 0:12:02.120 But whoa yeah, yeah, Well, when galaxies merge, what happens 0:12:02.200 --> 0:12:04.440 is the center's merge. It takes a long long time 0:12:04.520 --> 0:12:07.560 and then the black holes merge, but not always. And 0:12:07.640 --> 0:12:10.400 if you have like three galaxies merging at the same time, 0:12:10.559 --> 0:12:13.080 two of them can work together and eject the third one. 0:12:13.760 --> 0:12:17.080 And so yeah, gravitational kicks can eject the super massive 0:12:17.120 --> 0:12:19.680 black hole from the core. It's not something we understand 0:12:19.760 --> 0:12:22.280 super well. We do think that there are super massive 0:12:22.280 --> 0:12:24.920 black holes at the cores of these galaxies. So imagine 0:12:24.960 --> 0:12:28.040 a very very dense center of the galaxy and then 0:12:28.400 --> 0:12:31.720 fewer stars as you move away from the center, and 0:12:31.760 --> 0:12:34.160 then from the center shooting up and down. Are these 0:12:34.320 --> 0:12:37.560 massive astrophysical jets. They can go for like hundreds of 0:12:37.600 --> 0:12:38.800 thousands of light years. 0:12:39.120 --> 0:12:39.480 Wow. 0:12:39.600 --> 0:12:43.160 But they're not necessarily coming from the super massive black hole, 0:12:43.240 --> 0:12:45.120 but just from like the general center. 0:12:45.320 --> 0:12:47.439 We're going to dig into that later in the episode. 0:12:47.480 --> 0:12:49.920 But we think they are connected. Yes, And this was 0:12:49.920 --> 0:12:52.760 one of the central puzzles of astrophysical jets and continues 0:12:52.800 --> 0:12:54.800 to be like what exactly is powering them? It's a 0:12:54.840 --> 0:12:55.760 really fun question. 0:12:56.200 --> 0:12:58.840 Okay, so stuff is shooting out, is it just kind 0:12:58.840 --> 0:13:01.920 of like trickling out or is it moving really fast? 0:13:02.120 --> 0:13:05.400 These are some of the fastest things in the universe. Like, 0:13:05.520 --> 0:13:09.400 these jets are shooting particles out, often very close to 0:13:09.400 --> 0:13:11.880 the speed of light. Like the energy of particles in 0:13:11.920 --> 0:13:16.160 these jets is often much higher than energy of particles 0:13:16.200 --> 0:13:19.400 in our experiments here on Earth, like the Large Hadron Collider, 0:13:19.440 --> 0:13:22.280 we accelerate particles to have an energy of like around 0:13:22.400 --> 0:13:27.840 five to seven tarra electron volts. That's trillions of electron volts. 0:13:28.240 --> 0:13:32.520 But these galactic centers can accelerate particles to much higher energies, 0:13:32.840 --> 0:13:35.959 which connects to lots of fascinating mysteries, like we see 0:13:36.000 --> 0:13:38.920 super high energy particles arriving on Earth and we don't 0:13:38.960 --> 0:13:41.400 understand where they come from. And one theory is that 0:13:41.400 --> 0:13:45.840 they're being kicked to super high energy by these galactic accelerators. 0:13:45.960 --> 0:13:50.040 Essentially that these centers of galaxies are like enormous guns 0:13:50.160 --> 0:13:52.880 shooting out particles at super high energies. 0:13:53.080 --> 0:13:55.679 But then you so you shoot the particles out, and 0:13:55.720 --> 0:13:58.040 then where do they go? What happens to them? 0:14:00.160 --> 0:14:02.560 Well, if you believe that it's natural, right, and there's 0:14:02.600 --> 0:14:05.160 really fun theories out there about how like maybe aliens 0:14:05.240 --> 0:14:08.280 have megastructures and they're engineering the centers of galaxies to 0:14:08.320 --> 0:14:12.199 do particle physics experiments. That would be awesome two galaxies 0:14:12.240 --> 0:14:14.920 pointing at each other. But in general, they just shoot 0:14:14.960 --> 0:14:17.480 out into the universe. And you can see these astrophysical 0:14:17.559 --> 0:14:19.800 jets if you look at it in the right spectrum, 0:14:20.120 --> 0:14:23.520 really beautiful. You should google these images. They're spectacular. Often 0:14:23.560 --> 0:14:26.840 these things are bigger than the galaxies themselves. They just 0:14:26.840 --> 0:14:28.960 shoot out into the universe and then you know there 0:14:29.000 --> 0:14:31.160 are magnetic fields out there in the universe, and these 0:14:31.200 --> 0:14:34.200 are mostly charged particles and so they bend and they 0:14:34.240 --> 0:14:37.640 fly around. And one reason why we like to study 0:14:37.720 --> 0:14:40.520 the cosmic rays, the super high energy cosmic raise is 0:14:40.520 --> 0:14:43.480 that they are less bent than the other particles. So 0:14:43.520 --> 0:14:45.800 you want to know where something came from. If it's 0:14:45.800 --> 0:14:48.640 like gotten bent and zipped around and changed direction one 0:14:48.680 --> 0:14:51.280 hundred times, it's hard to tell. But if it's come 0:14:51.440 --> 0:14:54.320 mostly straight at you, and high energy particles get less 0:14:54.360 --> 0:14:56.600 bent by magnetic fields, then it's easier to sort of 0:14:56.600 --> 0:14:59.160 point back in the sky and say where it came from. 0:15:00.040 --> 0:15:02.240 Reason why we look for the super high energy particles 0:15:02.240 --> 0:15:04.760 because they tend to point back to their source more 0:15:04.840 --> 0:15:07.280 than lower energy particles. Yeah, very cool. 0:15:07.560 --> 0:15:10.200 Okay, so they're going really fast. It's a lot of 0:15:10.200 --> 0:15:10.960 different stuff. 0:15:11.760 --> 0:15:13.960 Is this like a narrow beam or is this like 0:15:14.000 --> 0:15:15.320 pretty wide and spread out. 0:15:15.560 --> 0:15:18.400 It's pretty narrow like when they were first discovered, And 0:15:18.400 --> 0:15:20.520 we'll dig into that. These are little sources like in 0:15:20.560 --> 0:15:24.040 the sky. They're pretty small, which is one reason why 0:15:24.080 --> 0:15:27.080 it was such a puzzle. And it's sort of amazing. 0:15:27.400 --> 0:15:29.600 And you know, you have these galaxies and they're emitting 0:15:29.680 --> 0:15:32.400 these things up and down the north and south pole 0:15:33.080 --> 0:15:36.600 from the center and it's fascinating because it's not shot 0:15:36.600 --> 0:15:40.040 out by the super massive black hole itself. Obviously, black 0:15:40.080 --> 0:15:42.640 holes do not emit photons. It's not like, you know, 0:15:42.760 --> 0:15:46.000 black holes are shooting particles out into space or anything 0:15:46.040 --> 0:15:49.320 like that. But the environment the black hole creates, and 0:15:49.360 --> 0:15:53.200 in general, the environment of the galaxy might be the 0:15:53.240 --> 0:15:56.160 thing that's powering these particles and creating these beams. 0:15:56.440 --> 0:15:56.880 Awesome. 0:15:57.080 --> 0:15:59.440 So we've gotten to the what, and now we're going 0:15:59.480 --> 0:16:01.440 to take a break, and then we'll get to the why. 0:16:01.640 --> 0:16:25.680 Why do you get astrophysical jets? Not the baseball team? 0:16:25.720 --> 0:16:29.240 All right, we're back. We've described astrophysical jets, and now 0:16:29.360 --> 0:16:32.160 Daniel's going to help us understand why you get these 0:16:32.640 --> 0:16:35.160 bursts of loads of different kinds of things coming out 0:16:35.160 --> 0:16:36.280 of the center of galaxies. 0:16:36.520 --> 0:16:38.440 Yeah, and I think a fun way to attack this 0:16:38.920 --> 0:16:40.880 is to take us through the history in the last 0:16:40.880 --> 0:16:43.800 century of people trying to understand them and putting together 0:16:44.160 --> 0:16:49.200 lots of different things simultaneously. Because astrophysical jets are connected 0:16:49.240 --> 0:16:52.760 to something else we've probably heard about, which are quasars. 0:16:53.360 --> 0:16:56.000 Let's put astrophysical jets in our pocket for a minute 0:16:56.520 --> 0:16:59.880 and talk about the history of quasars, why they were confusing, 0:17:00.080 --> 0:17:02.160 how we understand them, and then how they come back 0:17:02.160 --> 0:17:04.840 together to help us understand astrophysical jets. 0:17:04.920 --> 0:17:06.320 Let's get into the quasar question. 0:17:07.359 --> 0:17:10.040 So quasars are fun because, like the word itself is 0:17:10.119 --> 0:17:13.480 like sounds super cool and science fiction. And they're name 0:17:13.720 --> 0:17:16.960 because we didn't understand what they were, right. So quasars 0:17:17.000 --> 0:17:21.320 are short for quasi stellar objects. And they were first 0:17:21.320 --> 0:17:23.800 found back in the nineteen fifties when we didn't really 0:17:23.840 --> 0:17:26.439 understand a lot about the galaxy. Oh it's only like 0:17:26.600 --> 0:17:28.840 twenty or thirty years since we understood that there were 0:17:29.000 --> 0:17:32.119 other galaxies out there in the universe, and we started 0:17:32.160 --> 0:17:34.800 studying these things they called nebula that turned out to 0:17:34.800 --> 0:17:38.040 be other distant galaxies. And then in parallel, we had 0:17:38.080 --> 0:17:40.960 the birth of radio astronomy. You know, astronomy used to 0:17:41.000 --> 0:17:42.960 be just in the optical like you look through a 0:17:42.960 --> 0:17:45.000 telescope and you see, what do I see out there? 0:17:45.000 --> 0:17:47.880 And let's make a map? But radio and World War 0:17:47.920 --> 0:17:51.360 two led to the advent of radio telescopes. People listening 0:17:51.400 --> 0:17:54.720 to the sky in the radio and what they found 0:17:54.840 --> 0:17:58.000 were these radio sources in the nineteen fifties where they 0:17:58.040 --> 0:18:01.560 couldn't find any optical objects as well. They were like hmm, 0:18:01.560 --> 0:18:04.679 there's something out there that's emitting in the radio, but 0:18:04.720 --> 0:18:07.480 the telescopes at the time couldn't see anything there in 0:18:07.520 --> 0:18:09.679 the visible so they're like, what are these things? 0:18:10.000 --> 0:18:13.600 So then are they quasi objects because they're like, maybe 0:18:13.600 --> 0:18:16.240 that's from space. I don't know, maybe we messed something up, 0:18:16.640 --> 0:18:18.200 like why, yeah, why the quasi part? 0:18:18.640 --> 0:18:21.240 Yeah exactly. They didn't understand what they were, so they're like, 0:18:21.240 --> 0:18:24.119 maybe there's something like stars because they're sort of localized, 0:18:24.200 --> 0:18:27.040 but there's no visible object there initially, so it was 0:18:27.080 --> 0:18:28.880 a real mystery at first, which is why I think 0:18:28.920 --> 0:18:30.959 they went for like, let's give this kind of a 0:18:31.000 --> 0:18:34.840 fuzzy name so we don't know, we don't paint ourselves 0:18:34.840 --> 0:18:37.040 in the corner, which hey, maybe that was wise. 0:18:37.280 --> 0:18:39.159 Oh yeah, so maybe after they figured out what it was, 0:18:39.200 --> 0:18:41.639 they should have called it like straight up stellar objects, 0:18:41.680 --> 0:18:43.560 like we're totally sure about this. 0:18:43.680 --> 0:18:45.879 But they're not stars, right, they're not stars, So it 0:18:45.960 --> 0:18:47.280 was good that they left. 0:18:47.040 --> 0:18:50.840 That fuzz Oh so stellar means star, not just like spacey. 0:18:50.640 --> 0:18:52.920 Yes, exactly, like a star. 0:18:53.160 --> 0:18:56.600 Yeah, yeah, Kelly is really good with words. 0:18:56.320 --> 0:19:00.240 All right, Moving on, and they knew it was that 0:19:00.240 --> 0:19:03.199 they had a very small angular size, right, like they 0:19:03.200 --> 0:19:05.399 could tune the radio telescopes in a certain direction and 0:19:05.480 --> 0:19:07.680 see it and then turn it a little further away 0:19:07.760 --> 0:19:09.880 and not see it right, and so you could tell 0:19:09.920 --> 0:19:12.159 that this thing was coming from a localized spot in 0:19:12.200 --> 0:19:15.320 the sky. And by the sixties there were like hundreds 0:19:15.320 --> 0:19:18.399 of these things had been cataloged, and so people started 0:19:18.440 --> 0:19:21.080 a dedicated search for like, let's look to see if 0:19:21.119 --> 0:19:24.920 we can find something that corresponds to them. And then 0:19:25.040 --> 0:19:27.480