WEBVTT - Listener Questions 7 0:00:08.640 --> 0:00:11.400 Hey, Daniel, have we gotten any exciting messages in our 0:00:11.480 --> 0:00:15.000 podcast mailbox recently? Oh? Yeah, I gotta say it's kind 0:00:15.000 --> 0:00:17.880 of refreshing because now the questions in the inbox are 0:00:17.960 --> 0:00:22.360 mostly back to asking science questions. Back to asking science questions. 0:00:22.360 --> 0:00:25.600 What do you mean have they not always been about science? Well, 0:00:25.680 --> 0:00:28.159 you know, until a couple of weeks ago, most of 0:00:28.160 --> 0:00:32.000 the questions we're asking something else. Here's an example. Hi, 0:00:32.120 --> 0:00:34.479 Daniel Horror. Hey, this is Oliver and I am a 0:00:34.560 --> 0:00:39.720 very important question about the universe. Where is Horgey? Thanks? 0:00:39.880 --> 0:00:44.920 I love your show. Oh that's so cute. Thanks. Thanks 0:00:44.960 --> 0:00:49.880 for the concern, Oliver. But do you prefer science questions? Daniel? 0:00:50.400 --> 0:00:53.400 Science questions have answers, you know, science questions or something. 0:00:53.440 --> 0:00:55.960 I'm supposed to be an expert about. Where Jorge is 0:00:56.360 --> 0:01:15.720 nobody knows. Hi. I'm or Hamm, a cartoonists and the 0:01:15.720 --> 0:01:19.280 creator of peach d Comics. Hi. I'm Daniel Whitson. I'm 0:01:19.319 --> 0:01:23.319 a particle physicist and an avid answer of listener questions. 0:01:23.600 --> 0:01:26.759 Welcome to our podcast, Daniel and Jorge Explain the Universe, 0:01:26.920 --> 0:01:30.120 a production of I Heart Radio. Yeah, this is our 0:01:30.120 --> 0:01:34.000 podcast where we talk about the great Big Unknown questions 0:01:34.000 --> 0:01:37.080 of the universe, what's going on out there? And often 0:01:37.120 --> 0:01:39.560 we deal with the questions at the forefront of science. 0:01:39.680 --> 0:01:43.000 What are scientists thinking, what are they trying to figure out? Zooming? 0:01:43.040 --> 0:01:45.160 You are all around the universe to take you to 0:01:45.160 --> 0:01:47.440 the forefront of science and explain it to you. But 0:01:47.600 --> 0:01:50.360 sometimes we also like to answer questions not just in 0:01:50.400 --> 0:01:52.960 the minds of scientists, but in the minds of everybody 0:01:53.000 --> 0:01:55.880 out there. Sometimes I bet some of the great questions 0:01:55.880 --> 0:01:58.800 and science come from just regular people wondering about this 0:01:58.880 --> 0:02:01.320 kind of stuff. Hey, socientists are regular people? Are you 0:02:01.320 --> 0:02:06.120 suggesting we're not? What what you think? I put on 0:02:06.120 --> 0:02:07.640 that lab code and all of a sudden I become 0:02:07.680 --> 0:02:12.480 somebody else. Yeah, you become irregular. I'm going to take 0:02:12.520 --> 0:02:16.720 that in the best way possible. But I think you're right. 0:02:16.760 --> 0:02:18.640 I agree with you. I think that a lot of 0:02:18.680 --> 0:02:20.760 the questions that are at the forefront of science, the 0:02:20.840 --> 0:02:23.200 questions that are burning, that are deep, that are fascinating, 0:02:23.440 --> 0:02:26.720 our questions that everybody has because everybody wants to know 0:02:26.800 --> 0:02:29.280 the answer to questions about the universe. People wonder how 0:02:29.280 --> 0:02:31.560 do things work, and how do they start? And could 0:02:31.600 --> 0:02:33.480 we blow up planets? And you know, these are basic 0:02:33.520 --> 0:02:35.560 questions everybody wants to know the answer to. Yes, So 0:02:35.639 --> 0:02:37.760 to the on the episode. This will be I think 0:02:38.000 --> 0:02:42.440 maybe episode seven in our series of answering listener questions. 0:02:42.960 --> 0:02:46.680 So today we have some really interesting questions here about 0:02:46.800 --> 0:02:51.280 what happens when black holes are born and whether or 0:02:51.320 --> 0:02:54.880 not we can build something out of a nineteen six movie. 0:02:56.080 --> 0:02:58.560 That's right, and we love answering listener questions. If you 0:02:58.639 --> 0:03:01.359 have a question about the universe you'd like us to answer, 0:03:01.440 --> 0:03:03.840 please send it to us at questions at Daniel and 0:03:03.919 --> 0:03:06.880 Jorge dot com. We right back to every email, hopefully 0:03:06.880 --> 0:03:09.600 with an insiphle answer, and sometimes we even feature those 0:03:09.680 --> 0:03:12.840 questions here on the podcast. Yeah, we answered everything except 0:03:12.919 --> 0:03:16.239 where I am that one? Oh No, I right back, 0:03:16.240 --> 0:03:19.519 and I just say, I don't know. I just work 0:03:19.600 --> 0:03:24.960 with this guy like three different projects. How would I know? Yeah, 0:03:25.000 --> 0:03:27.359 that's basically it. Yeah, So today on the podcast we'll 0:03:27.360 --> 0:03:36.600 be answering listener questions, and we have what happens at 0:03:36.640 --> 0:03:38.960 the moment a black hole is made? Can we build 0:03:39.040 --> 0:03:41.960 a death star? Those are the burning questions in our 0:03:42.000 --> 0:03:45.080 listeners minds, and I just want to encourage you one 0:03:45.120 --> 0:03:47.680 more time to send us to your questions. Sometimes I 0:03:47.720 --> 0:03:49.720 know the answer run off the bat, but sometimes I 0:03:49.760 --> 0:03:51.960 have to go do a little bit of research. Talk 0:03:52.080 --> 0:03:54.720 to an expert on black holes, talk to an expert 0:03:54.720 --> 0:03:57.520 about death stars, and that's a lot of fun. So 0:03:57.600 --> 0:04:00.640 please continue to send in your questions, not just because 0:04:00.640 --> 0:04:02.360 it sends me down rabbit holes where I get to 0:04:02.440 --> 0:04:05.000 learn about crazy stuff, but also because if you have 0:04:05.040 --> 0:04:08.720 a question about the universe, probably somebody else does too. Wait, Dinel, 0:04:08.760 --> 0:04:10.680 I have two questions just from what you just said. 0:04:10.720 --> 0:04:12.600 First of all, you're you're not an expert at at 0:04:12.680 --> 0:04:16.080 everything in the universe. I'm an expert at putting on 0:04:16.080 --> 0:04:19.640 a lab coat and sounding like an expert who gave 0:04:19.640 --> 0:04:23.400 you a microphone? What? And the second question is that 0:04:23.480 --> 0:04:26.680 there's actually an expert on death stars out there in 0:04:26.800 --> 0:04:31.680 your department or in some university. Yes, absolutely, they are experts. 0:04:31.720 --> 0:04:35.000 In astro industry. You know you're gonna build something really big. 0:04:35.279 --> 0:04:36.920 You're not going to assemble it on the surface of 0:04:36.920 --> 0:04:38.880 the Earth. You're gonna have to build it in space. 0:04:38.960 --> 0:04:43.240 And surprisingly people have thought about that astro engineering. Yeah, 0:04:43.240 --> 0:04:46.960 astro engineering. Can you study that in college? Can I 0:04:46.960 --> 0:04:52.279 study that in college? Not today, not tomorrow, but coming 0:04:52.360 --> 0:04:54.919 soon to a rebel planet near you. Maybe we should 0:04:54.920 --> 0:04:56.920 take a page from our president and just call it 0:04:57.040 --> 0:05:00.400 a space engineer Space force engineering US spence much time 0:05:00.400 --> 0:05:02.680 wondering if you could build a death star. You never 0:05:02.720 --> 0:05:04.920 thought to ask if you should. Yeah, but we love 0:05:04.960 --> 0:05:07.960 getting questions from listeners, and so today the first question 0:05:08.000 --> 0:05:10.719 we have is from Glenn, who is from Cape Town, 0:05:10.839 --> 0:05:14.320 South Africa. And Glenn has a pretty interesting question which 0:05:14.400 --> 0:05:16.880 I don't think we've ever covered here, right, No, we 0:05:17.000 --> 0:05:19.560 certainly have not. We've talked a lot about black holes, 0:05:19.600 --> 0:05:23.760 but we've never really asked or answered this specific question. Yeah, so, 0:05:23.880 --> 0:05:26.000 and um, it's a pretty cool question. And so here 0:05:26.080 --> 0:05:30.240 is Glenn from Cape Town, South Africa. Hi, Daniel and Joge. 0:05:30.520 --> 0:05:33.200 This is Glenn Edwards and I'm from Cape Town, South Africa. 0:05:34.040 --> 0:05:36.600 I'm pretty interested in all things space related and I've 0:05:36.600 --> 0:05:39.360 been really enjoying your podcasts. I've heard a lot of 0:05:39.760 --> 0:05:42.240 different discussions about black holes, so I have a very 0:05:42.240 --> 0:05:45.280 basic understanding about the factors that lead up to its formation. 0:05:46.080 --> 0:05:48.400 One thing, however, that I've never heard about, is the 0:05:48.440 --> 0:05:51.840 actual mechanics of the moment of black hole begins when 0:05:51.960 --> 0:05:55.159 extremely dense cosmic object collapses into a black hole. Is 0:05:55.200 --> 0:05:58.479 this an instantaneous event or something that happens over cosmic 0:05:58.520 --> 0:06:01.599 time frames? If you are observing this object at the 0:06:01.600 --> 0:06:04.080 moment of collapse, would it suddenly go out like a light? 0:06:05.160 --> 0:06:08.200 Have any black hole formation has ever been observed? Would 0:06:08.200 --> 0:06:13.040 anything within the Schwartz Child radius suddenly disappear? That's a 0:06:13.040 --> 0:06:15.360 lot to unpeck, but I'm looking forward to hearing your 0:06:15.480 --> 0:06:18.719 entertaining answers. All Right, Basically, I think the question is 0:06:18.760 --> 0:06:22.320 what does the baby black hole look like? For or 0:06:22.360 --> 0:06:25.200 maybe it's more like a bird's in the best question 0:06:25.200 --> 0:06:27.640 about black hole? Yeah, I think he wants to see 0:06:27.880 --> 0:06:30.360 the black hole pop out. He's curious about that transition 0:06:30.760 --> 0:06:33.040 from not black hole to black hole? What does that 0:06:33.080 --> 0:06:35.320 look like? How does it happen? This kind of stuff, Yeah, 0:06:35.360 --> 0:06:37.880 because you know, we have sort of pictures now of 0:06:37.960 --> 0:06:40.280 what a black hole, an adult black hole looks like, 0:06:40.720 --> 0:06:43.560 but we don't know kind of like the process of 0:06:43.600 --> 0:06:46.840 making a black hole. Yeah, really a fascinating question. How 0:06:46.880 --> 0:06:48.680 does that happen, How fast does it happen? What would 0:06:48.720 --> 0:06:51.719 it look like if you were there watching? This really 0:06:51.760 --> 0:06:53.680 goes to the heart of what it's like to be 0:06:53.720 --> 0:06:55.560 a black hole and how the black hole has made 0:06:55.839 --> 0:06:57.839 So I thought this was a really fascinating question and 0:06:57.839 --> 0:07:00.000 actually went down and spent like an hour of talking 0:07:00.120 --> 0:07:02.839 to an expert in my department, Aaron Barth, who's an 0:07:02.839 --> 0:07:06.279 expert in black holes supermassive and not supermassive about exactly 0:07:06.279 --> 0:07:08.359 what this would look like. Super fun. Thank you Glenn 0:07:08.400 --> 0:07:10.800 for this excellent question. That's the question, And it's like, 0:07:10.840 --> 0:07:13.240 if you were out in space watching the birth of 0:07:13.280 --> 0:07:16.520 a black hole, what would you see? Would you would 0:07:16.520 --> 0:07:19.360 you even survive the experience? I guess this is my 0:07:19.480 --> 0:07:22.240 main question. Do we want to see a black hole 0:07:22.560 --> 0:07:24.600 get born? Well, maybe if you were watching it from 0:07:24.640 --> 0:07:26.720 the viewing portal of a death star and had like, 0:07:26.880 --> 0:07:29.120 you know, a lot of protection, then you could survive 0:07:29.120 --> 0:07:31.400 at force field a force field. But I think the 0:07:31.760 --> 0:07:34.360 first thing to understand is sort of the time scale 0:07:34.400 --> 0:07:37.280 of the process, Like how rapidly does a black hole 0:07:37.320 --> 0:07:39.720 get formed? Like how quickly do you go from star 0:07:39.840 --> 0:07:43.679 to black hole? Is it like geological cosmological time scales 0:07:43.680 --> 0:07:45.800 of hundreds of millions of years or does it happen 0:07:45.840 --> 0:07:48.040 really fast? I think that was the first question that 0:07:48.040 --> 0:07:51.880 popped into my head when I read this. My question is, um, 0:07:51.960 --> 0:07:55.640 what reminds me what a black hole is? Or like, 0:07:55.680 --> 0:07:58.200 what's a technical definition so that we know at what 0:07:58.360 --> 0:08:01.920 point it is a black hole? Right? Good point? So 0:08:02.080 --> 0:08:05.600 a black hole is any location in the universe where 0:08:05.600 --> 0:08:10.080 gravity is so strong that nothing can escape its gravitational field, 0:08:10.640 --> 0:08:13.720 and an area of volume of space or like a point, 0:08:14.200 --> 0:08:17.320 or it's a it's a volume of space, it's like 0:08:17.760 --> 0:08:20.600 a sphere, and we don't know what's inside the sphere. 0:08:20.640 --> 0:08:22.680 We don't know how the matter is distributed. A lot 0:08:22.680 --> 0:08:24.480 of people have their an image in their mind of 0:08:24.680 --> 0:08:28.520 a point like a singularity, a super dense point inside 0:08:28.560 --> 0:08:31.120 the black hole that has so much mass that the 0:08:31.160 --> 0:08:34.880 gravity around it is really strong. And that's the picture 0:08:34.920 --> 0:08:37.880 you have from general relativity. And we know the general 0:08:37.920 --> 0:08:40.199 relativity is a great theory. The university describes a lot 0:08:40.200 --> 0:08:43.280 of things correctly. We don't know that it's correctly describing 0:08:43.320 --> 0:08:45.720 what's happening inside a black hole, but it's it's a 0:08:45.720 --> 0:08:48.760 good starting point. And and the structure there is you 0:08:48.800 --> 0:08:52.000 have a dense dot and the singularity huge amount of mass, 0:08:52.440 --> 0:08:55.280 and then at some radius, some distance from the black 0:08:55.280 --> 0:08:58.760 hole or closer, the gravity is too strong for anything 0:08:58.800 --> 0:09:00.800 to escape, and that's what we sort of called the 0:09:00.800 --> 0:09:03.760 surface the black hole. It's a three D hole, right, 0:09:03.880 --> 0:09:07.840 like a it's like a sphere, but it's a whole. Yeah, 0:09:08.000 --> 0:09:09.760 in space. I think if it's sort of like a 0:09:10.080 --> 0:09:12.120 like a trap in space, like once you get in there, 0:09:12.160 --> 0:09:14.880 you can't get out. That space is sort of one directional, 0:09:15.240 --> 0:09:16.600 Like you get in there and all you can do 0:09:16.679 --> 0:09:18.680 is move closer to the center of the black hole. 0:09:18.880 --> 0:09:22.240 You can't ever move further from the center. Um in 0:09:22.320 --> 0:09:24.640 some sense, like you just call it a trap trap hole. 0:09:26.280 --> 0:09:31.000 I think that was vetoed is not safe to work um. 0:09:31.040 --> 0:09:33.440 And one useful thing to remember is that it's not 0:09:33.520 --> 0:09:37.280 like gravity is pulling on photons and slowing them down, 0:09:37.320 --> 0:09:40.480 but eventually they will escape. They cannot escape, and not 0:09:40.559 --> 0:09:42.679 just because gravity is so strong, but because gravity is 0:09:42.679 --> 0:09:46.000 actually bent the space. You know, there's there's no path 0:09:46.360 --> 0:09:49.839 outside the black hole. Like every direction you move you're 0:09:49.840 --> 0:09:52.920 inside the black hole takes you closer because space is 0:09:52.960 --> 0:09:55.600 bent in a really weird way inside the black hole. 0:09:55.800 --> 0:09:57.920 So it's not like it it grabs things and holds 0:09:57.960 --> 0:10:00.400 them with some force. It's like it's like it's really 0:10:00.480 --> 0:10:02.200 kind of like a pocket in space. It's like a 0:10:02.280 --> 0:10:05.320 hole in space itself. Like you once you go in there, 0:10:05.880 --> 0:10:08.839 you're trapped in It's in your own little space, that's right. 0:10:09.240 --> 0:10:11.200 And it's not like quicksand right where it's just like 0:10:11.240 --> 0:10:13.120 slows you down. It's hard to climb out, but if 0:10:13.120 --> 0:10:15.600 you try really really hard or whatever, um there's just 0:10:15.679 --> 0:10:17.880 no way to do it. And so it's like a trap. 0:10:17.880 --> 0:10:20.040 It's like a hole in space. And and the point 0:10:20.080 --> 0:10:22.480 I wanted to make earlier was that we know this 0:10:22.640 --> 0:10:24.880 surface exists, We know the black holes are real, and 0:10:24.920 --> 0:10:27.960 that there's this event horizon the surface beyond which if 0:10:27.960 --> 0:10:30.560 you pass you can never escape. We don't know what's 0:10:30.559 --> 0:10:33.000 going on inside there, because we don't really know if 0:10:33.040 --> 0:10:36.720 general relativity is correct at these really really strong gravitational fields, 0:10:36.720 --> 0:10:40.080 and quantum mechanics says it's probably wrong, but we've never 0:10:40.160 --> 0:10:42.160 looked inside a black hole, so we can't quite tell. 0:10:42.480 --> 0:10:44.320 But it is um, like you said, it does have 0:10:44.360 --> 0:10:47.120 sort of a surface reboundary, and so it's a it's 0:10:47.120 --> 0:10:49.520 a thing, And so I guess the question is like, 0:10:49.559 --> 0:10:52.440 how does that thing get formed? Does it started really 0:10:52.480 --> 0:10:56.239 small and then grow or does it immediately pop into existence? 0:10:56.440 --> 0:10:58.720 You just go online to Amazon and you enter black 0:10:58.760 --> 0:11:01.080 hole and you press by now and boom, there's your 0:11:01.080 --> 0:11:04.720 black hole. There's a buy now button for the universe 0:11:04.800 --> 0:11:08.440 only for Prime Now I get black hole Prime delivery. Um, 0:11:08.480 --> 0:11:11.040 it's it's quantum Amazon. I was actually thinking about that 0:11:11.080 --> 0:11:15.440 because the gravitational information travels at a finite speed. Right. 0:11:15.640 --> 0:11:19.199 If you create a black hole as a singularity, then 0:11:19.200 --> 0:11:22.440 the space around it doesn't know about the black hole instantly, 0:11:22.480 --> 0:11:24.760 so it takes like a moment for the black hole 0:11:24.800 --> 0:11:28.600 the sphere to sort of be created and to travel 0:11:28.640 --> 0:11:30.640 out to the eventual event horizon. There's like a huge 0:11:30.679 --> 0:11:33.240 gravitational wave that would be created if you were able 0:11:33.280 --> 0:11:36.880 to Amazon prime singularity into existence. Yeah, the question is 0:11:37.080 --> 0:11:40.319 if you instantly pop a singularity out into space, Um, 0:11:40.600 --> 0:11:43.319 what happens? Right, Like you're saying, it may not. It 0:11:43.400 --> 0:11:46.720 might propagate out slowly, or it might um who knows, right, 0:11:46.760 --> 0:11:48.800 because it's bending space at the same time. So it's 0:11:48.880 --> 0:11:50.880 it's kind of weird, right. Yeah. If you were a 0:11:50.880 --> 0:11:53.840 photon and you're flying in some direction and somebody creates 0:11:53.840 --> 0:11:57.440 a black hole right behind you, in theory, you could 0:11:57.520 --> 0:12:00.600 survive even if you're right next to that singular already 0:12:00.640 --> 0:12:04.120 because you could like travel faster than the gravitational waves 0:12:04.160 --> 0:12:06.360 that are propagatting out from the singularity to sort of 0:12:06.520 --> 0:12:10.439 inform the rest of the universe that singularity have been created. 0:12:10.480 --> 0:12:14.520 Because remember, gravitational information is not instantaneous. The Sun disappeared, 0:12:14.720 --> 0:12:17.240 for example, the Earth would keep moving in its orbit 0:12:17.280 --> 0:12:20.840 for eight minutes until it got updated. Right, It's like 0:12:20.880 --> 0:12:23.160 that scene in every other action movie where there's an 0:12:23.200 --> 0:12:25.640 explosion or a tidal wave or something and the heroes 0:12:25.679 --> 0:12:28.119 are in their plane or a car just barely outrunning 0:12:29.960 --> 0:12:33.800 the shock wave. No no, no, no, exactly they die 0:12:33.840 --> 0:12:36.000 from the burning building. But that's not the way black 0:12:36.000 --> 0:12:38.199 holes are actually made in our universe. It's just sort 0:12:38.240 --> 0:12:40.959 of like the extreme example, black holes come from huge 0:12:41.000 --> 0:12:43.600 masses that already exist. Okay, so let's step through that 0:12:43.720 --> 0:12:47.520 how exactly black holes are made and what maybe actually 0:12:47.559 --> 0:12:50.240 happens when they get made. But first let's take a 0:12:50.320 --> 0:13:05.480 quick break. Okay, Daniel, So how do I make a 0:13:05.559 --> 0:13:08.679 black hole? What's the what's the recipe here? It's a 0:13:08.840 --> 0:13:11.920 huge blob of stuff and that's about it. Get a 0:13:12.000 --> 0:13:17.880 huge blob tablespoons of the zillion tablespoons of anything and 0:13:17.920 --> 0:13:20.200 then mix. That's the recipe. You don't even have to mix. 0:13:20.240 --> 0:13:22.760 You just wait, you know, preheat the oven to two 0:13:22.760 --> 0:13:25.559 point seven three degrees kelvin. That's a temperature of the universe. 0:13:25.600 --> 0:13:28.640 And then just wait hundreds of millions of years. Well, 0:13:28.679 --> 0:13:31.040 you kind of have to um make a dough in 0:13:31.120 --> 0:13:32.800 no way, right, You have to get it on the 0:13:33.160 --> 0:13:35.320 in a certain amount of space. Like, you don't just 0:13:35.360 --> 0:13:37.080 need a lot of stuff. You need a lot of 0:13:37.080 --> 0:13:39.719 stuff in a small amount of space. Yeah, And that's 0:13:39.720 --> 0:13:42.000 what gravity will do for you. Given enough time, gravity 0:13:42.000 --> 0:13:44.960 will pull together a huge blob of gas and squeeze 0:13:45.000 --> 0:13:47.600 it and eventually squeeze it so much that becomes a 0:13:47.640 --> 0:13:50.520 star if it's big enough, and that star will burn. 0:13:51.160 --> 0:13:53.960 And the reason it doesn't just immediately compress it into 0:13:53.960 --> 0:13:56.440 a black hole is because of the burning. The burning 0:13:56.480 --> 0:13:59.480 creates a lot of energy. It's like radiation that's pushing out, 0:13:59.720 --> 0:14:02.760 so keeps it from collapsing anymore. Like you might wonder 0:14:02.960 --> 0:14:05.280 why doesn't every blob of gas just immediately turn into 0:14:05.280 --> 0:14:07.920 a black hole, It's because there's some force outwards and 0:14:07.960 --> 0:14:10.680 that comes from this fusion. It's burning, and so it's 0:14:10.760 --> 0:14:14.080 kind of diffusing the stuff out, making it fluffy, not 0:14:14.240 --> 0:14:18.400 concentrated exactly. It's a constantly exploding fusion bomb, so it's 0:14:18.440 --> 0:14:21.560 throwing everything out really hard. At the same time gravity 0:14:21.640 --> 0:14:24.120 is pulling in, so it's a delicate balance. A star, 0:14:24.440 --> 0:14:28.040 it's this exploding bomb that's trapped by its own gravitational power, 0:14:28.640 --> 0:14:31.120 and that goes on for hundreds of millions of years, 0:14:31.160 --> 0:14:33.920 depending precisely on the size of the star, etcetera, while 0:14:33.920 --> 0:14:36.400 it burns all that fuel. Okay, so then how does 0:14:36.440 --> 0:14:38.840 a black hole get formed or how do what are 0:14:38.880 --> 0:14:42.360 the different wayte black holes come to exist in our universe? Well, 0:14:42.360 --> 0:14:44.120 the thing that's preventing a star from being a black 0:14:44.120 --> 0:14:46.400 hole immediately is this burning and so essentially you have 0:14:46.440 --> 0:14:48.800 to wait for the fire to go out. After hundreds 0:14:48.800 --> 0:14:51.200 of millions of years, it's turned that hydrogen into helium 0:14:51.240 --> 0:14:53.680 and then into lithium and into heavier stuff, and that 0:14:53.760 --> 0:14:56.400 stuff can burn also, but eventually it turns into something 0:14:56.440 --> 0:14:59.720 that can't burn, which is iron, and so it runs 0:14:59.720 --> 0:15:03.120 out of fuel. Most black holes come from stars? Is 0:15:03.120 --> 0:15:05.680 that is that the path through a black hole? Or 0:15:06.040 --> 0:15:08.720 can a black hole form any other way that's not 0:15:08.800 --> 0:15:12.359 through a star? We're not exactly sure, like the supermassive 0:15:12.360 --> 0:15:14.640 black holes that at the center of galaxies, we still 0:15:14.680 --> 0:15:16.960 don't know what seated them, Like if you try to 0:15:17.000 --> 0:15:18.880 model them just from coming from one star and then 0:15:18.920 --> 0:15:21.040 gobbling up other ones, there's not enough time for them 0:15:21.040 --> 0:15:23.400 to get that big, and so there's lots of different 0:15:23.400 --> 0:15:25.720 categories of black holes. But we think that's sort of 0:15:25.720 --> 0:15:28.640 your vanilla black hole that comes from a star happens 0:15:28.640 --> 0:15:31.000 in this way, but we don't know if that's the 0:15:31.040 --> 0:15:33.840 dominant fraction of black holes. Also, some black holes might 0:15:33.880 --> 0:15:36.040 have been made at the Big Bang. They're called primordial 0:15:36.080 --> 0:15:38.400 black holes, and those could still be flying around they 0:15:38.400 --> 0:15:40.760 were made in the Big Bang. Yeah, these are the 0:15:40.800 --> 0:15:44.520 o G black holes. So as the as the universe 0:15:44.600 --> 0:15:48.240 was expanding rapidly, like, that's how you got black holes. Yeah, Well, 0:15:48.240 --> 0:15:50.600 there was crazy energy density back then in the very 0:15:50.640 --> 0:15:53.160 first moment of the universe, and you quantum fluctuations and 0:15:53.200 --> 0:15:55.960 made some spots more dense and some spots less dense, 0:15:56.200 --> 0:15:58.320 and then all that stuff turned into all that energy 0:15:58.320 --> 0:16:00.680 turned into some kind of matter. Some it became very 0:16:00.720 --> 0:16:03.240 on it and became dark matter. Some fraction that we 0:16:03.280 --> 0:16:05.920 think might have turned into primordial black holes, which is 0:16:05.960 --> 0:16:09.480 just a cool word. Primordial black holes. Yeah, it's like 0:16:09.480 --> 0:16:11.760 a black hole emerging from the swamp. That's what I 0:16:11.760 --> 0:16:16.080 have this image in my head, swamp of what the 0:16:16.120 --> 0:16:20.000 swamp of the early universe, you know, pretty big bang. Yeah. 0:16:20.040 --> 0:16:21.880 So you say, most black holes we don't know how 0:16:22.000 --> 0:16:24.320 they're made, the big ones and the ones that were 0:16:24.360 --> 0:16:25.960 at the beginning of the universe. But a lot of 0:16:26.000 --> 0:16:28.520 the black holes we know about and see do come 0:16:28.560 --> 0:16:30.840 from a process that we know about, which is from 0:16:31.120 --> 0:16:34.440 collapsing stars. So it burns through all this fuel that's 0:16:34.560 --> 0:16:37.280 keeping it from collapsing, and it gets heavier and heavier 0:16:37.320 --> 0:16:39.760 and denser and denser, and then once it gets enough 0:16:39.800 --> 0:16:42.760 iron in the core, it can't support itself anymore. Gravity 0:16:42.760 --> 0:16:46.080 basically wins, and it starts crushing the star down even 0:16:46.120 --> 0:16:49.760 more and more dense, and then there's I then that's 0:16:49.760 --> 0:16:53.280 when it's super novas, right, Like, there's an event the 0:16:53.320 --> 0:16:55.720 black hole, and you know, like every good movie, the 0:16:55.760 --> 0:16:58.320 sort of drama accelerates. The first stage is really long 0:16:58.400 --> 0:17:00.440 and boring set up, like hundreds of millions of years 0:17:00.440 --> 0:17:02.960 of burning hydrogen, and then it burns helium and that's 0:17:03.040 --> 0:17:05.240 less time, and then it burns lithium or whatever, and 0:17:05.240 --> 0:17:07.480 that's less time in the last stage where it's like 0:17:07.560 --> 0:17:10.320 trying to burn iron, that last for about one hour 0:17:10.720 --> 0:17:13.879 and then it collapses and it's like that happens in 0:17:14.359 --> 0:17:17.240 seconds or less than a second, and the edge of 0:17:17.240 --> 0:17:19.399 the star collapses at something like a quarter of the 0:17:19.440 --> 0:17:21.960 speed of light. So the whole thing happens like really quickly. 0:17:22.000 --> 0:17:26.400 You go from star that's sputtering to collapsing, and then 0:17:26.440 --> 0:17:31.120 the whole star just kind of falls into itself. Yeah, 0:17:31.200 --> 0:17:33.240 and there's a lot of really interesting physics there, like 0:17:33.280 --> 0:17:36.320 it's collapsing so rapidly that you get shock waves, and 0:17:36.320 --> 0:17:39.439 those shock waves we think can create gamma ray bursts 0:17:39.480 --> 0:17:42.320 when like layers of the star bump into other layers 0:17:42.320 --> 0:17:44.639 of the star that aren't quite collapsing as quickly. We 0:17:44.720 --> 0:17:47.600 talked on this podcast once about these gamma ray bursts, 0:17:47.920 --> 0:17:50.520 hugely intense bursts of light that lasts like three or 0:17:50.640 --> 0:17:53.480 thirty seconds that come from places we don't understand. It 0:17:53.560 --> 0:17:55.680 might be the themes are happening sort of at these 0:17:55.760 --> 0:17:58.760 moments just before the supernova, at the creation of the 0:17:58.760 --> 0:18:01.520 black hole, but we're not sure. And it collapses from 0:18:01.640 --> 0:18:04.520 gravity right like there's no longer a fire kind of 0:18:04.600 --> 0:18:07.479 keeping everything out, and so everything just finally says, all right, 0:18:07.560 --> 0:18:11.560 we'll come together as gravity tells us precisely, and gravity 0:18:11.640 --> 0:18:13.960 just gets stronger and stronger a right. Gravity is just 0:18:14.000 --> 0:18:16.600 sort of like winds, you know, it's like interest in 0:18:16.600 --> 0:18:19.800 your bank account. The closer stuff it gets together, the 0:18:19.880 --> 0:18:22.000 more gravity pulls. The more gravity pulls, the closer it 0:18:22.040 --> 0:18:24.040 gets together, and then it accelerates, and so it gets 0:18:24.040 --> 0:18:26.840 really really strong. And then at some moment the gravity 0:18:26.880 --> 0:18:30.240 is strong enough that you get an event horizon that's formed. Oh, 0:18:30.400 --> 0:18:35.720 I say, it's pulling stuff in so quickly that you 0:18:35.840 --> 0:18:38.120 do get the conditions for a black hole. We talked 0:18:38.119 --> 0:18:42.320 before about like neutron stars. And sometimes a supernova doesn't 0:18:42.320 --> 0:18:45.760 result in a black hole, right, Sometimes it does, that's right. 0:18:45.800 --> 0:18:48.640 Sometimes it can come down to another dense state that's stable, 0:18:48.880 --> 0:18:52.119 like a neutron star. Everything has been squeezed so much 0:18:52.320 --> 0:18:55.600 that all the protons have absorbed electrons and turned into neutrons, 0:18:55.840 --> 0:18:58.320 and they've created this state that they can hold themselves 0:18:58.320 --> 0:19:02.160 together and resist gravity, like one last more gasp before 0:19:02.160 --> 0:19:04.399 it turns into a black hole. But sometimes it go 0:19:04.480 --> 0:19:06.840 straight to a black hole, right, And the difference is 0:19:06.880 --> 0:19:09.280 that just at the rate of how fast it collapsed 0:19:09.320 --> 0:19:11.680 or what. Most of the difference is the initial amount 0:19:11.680 --> 0:19:14.360 of stuff. If you have a big enough blob, then 0:19:14.400 --> 0:19:16.800 I think you get to skip the neutron star step 0:19:16.920 --> 0:19:18.440 and just go straight to a black hole. The whole 0:19:18.440 --> 0:19:20.960 thing happens more quickly the more mass you have. And 0:19:21.040 --> 0:19:23.399 really it's about density. I think you said once in 0:19:23.400 --> 0:19:26.040 the podcast, which is cool, that anything can become a 0:19:26.040 --> 0:19:28.320 black hole if you make it dense enough. And so 0:19:28.359 --> 0:19:31.120 we're not changing the mass of this initial blob of gas, 0:19:31.160 --> 0:19:33.760 We're just squeezing it down. At some point you make 0:19:33.800 --> 0:19:36.600 it dense enough, then you have more mass and less 0:19:36.640 --> 0:19:39.439 space than the gravity becomes strong enough to give you 0:19:39.440 --> 0:19:42.480 an event horizon. Right like you, You can be become 0:19:42.520 --> 0:19:44.679 a black hole. I can become a black hole. Everyone 0:19:44.720 --> 0:19:47.359 can be black if we're all o g black holes. 0:19:48.000 --> 0:19:51.120 I'm not primordial, man, I've been around to the Big 0:19:51.119 --> 0:19:53.560 Bang and you feel old. But gez, just because you 0:19:53.600 --> 0:19:58.879 get reading glasses, it doesn't make your primordial. No, that 0:19:59.000 --> 0:20:03.159 just makes me hyper my myopic. Um. And then it 0:20:03.200 --> 0:20:05.160 gets sort of back to this moment we were talking 0:20:05.160 --> 0:20:08.400 about before, when we like Amazon Prime to singularity into existence, 0:20:08.600 --> 0:20:10.680 because at some moment there's no event horizon, right, it's 0:20:10.680 --> 0:20:13.560 just a hot, dense star. And then at some moment 0:20:13.840 --> 0:20:16.919 there is because there's enough stuff there. It's a supernova. 0:20:16.960 --> 0:20:19.520 And I hit the pause button and I'm stepping through 0:20:19.560 --> 0:20:22.000 it super high speed frame by super high speed frame, 0:20:22.520 --> 0:20:26.119 and I'm seeing it collapse, collapse, collapse, and at some 0:20:26.240 --> 0:20:29.920