WEBVTT - What's Inside a Black Hole? 0:00:01.000 --> 0:00:04.520 Hey, Welcome to Sign Stuff, a production of iHeartRadio or 0:00:04.559 --> 0:00:07.520 Hit Him, And today we are answering the question what's 0:00:07.560 --> 0:00:11.160 inside a black hole? There's some of the most mysterious 0:00:11.160 --> 0:00:14.640 objects in the universe. Can we even tell what's inside 0:00:14.680 --> 0:00:17.599 of them? To find out, I asked three black hole 0:00:17.640 --> 0:00:21.040 experts this question, and they each gave me a different answer. 0:00:21.520 --> 0:00:25.120 That's how mysterious black holes are. We'll talk about each 0:00:25.120 --> 0:00:28.040 of these three ideas, and I have to warn you 0:00:28.400 --> 0:00:32.159 they each get wilder and wilder. So get ready to 0:00:32.200 --> 0:00:35.320 take the ultimate dive into the unknown as we get 0:00:35.360 --> 0:00:40.040 sucked into the question what's inside a black hole? Welcome 0:00:40.040 --> 0:00:47.360 to Sign Stuff, Hi everyone. Okay, Like I said, I 0:00:47.400 --> 0:00:50.440 asked three black hole experts what's inside a black hole? 0:00:50.720 --> 0:00:53.479 And they each gave me a different answer. So on 0:00:53.520 --> 0:00:56.520 the program today we'll hear what each expert said, and 0:00:56.800 --> 0:01:00.360 it's going to get crazier and crazier, not just because 0:01:00.360 --> 0:01:04.000 our experts have wild imaginations, but because that's what the 0:01:04.040 --> 0:01:07.760 math of black holes says. Okay. The first person I 0:01:07.840 --> 0:01:11.039 talked to was Professor Julie Commerford from the University of 0:01:11.040 --> 0:01:14.880 Colorado at Boulder. Doctor Cummerford and I made a video 0:01:15.040 --> 0:01:18.560 about super massive black holes for my YouTube channel YouTube 0:01:18.560 --> 0:01:21.600 dot com slash PhD Comics. They knew she'd be a 0:01:21.600 --> 0:01:24.600 fun person to talk to about black holes. So here's 0:01:24.600 --> 0:01:29.600 my conversation with Professor Julie Commerford. All Right, doctor Comerford, 0:01:29.640 --> 0:01:30.679 thank you for joining us. 0:01:30.800 --> 0:01:32.039 Yeah, thanks so much for having me. 0:01:32.280 --> 0:01:34.200 Can you go into a black hole and tell us 0:01:34.240 --> 0:01:35.240 what's inside? 0:01:35.440 --> 0:01:38.240 I know I'm having too much fun on Earth at 0:01:38.280 --> 0:01:41.200 the moment, but on my one hundredth birthday, I will 0:01:41.280 --> 0:01:43.840 vouch right now, I will volunteer to go on a 0:01:43.920 --> 0:01:46.080 rocket and you can send me into the super massive 0:01:46.080 --> 0:01:46.600 black hole. 0:01:49.720 --> 0:01:52.480 Now, before we talked about what's inside a black hole, 0:01:52.840 --> 0:01:55.240 I asked her to tell us what exactly a black 0:01:55.280 --> 0:01:58.880 hole is. Here's what she said, for those of us 0:01:58.920 --> 0:02:01.560 that don't know what is a black hole. 0:02:01.920 --> 0:02:04.480 A black hole is a region of space where the 0:02:04.480 --> 0:02:08.240 force of gravity is so intense that nothing can escape, 0:02:08.280 --> 0:02:11.959 no mass, no light, nothing can escape once you get 0:02:12.160 --> 0:02:16.400 too close to a black hole, and that special invisible 0:02:16.480 --> 0:02:20.639 boundary is called an event horizon, and that's the boundary 0:02:20.639 --> 0:02:24.240 across which you can no longer escape the strong gravity 0:02:24.240 --> 0:02:26.000 of a black hole, no matter how fast you go. 0:02:26.520 --> 0:02:29.720 So black hole is kind of like the Hotel California 0:02:29.800 --> 0:02:33.359 of space in that once you cross the event horizon, 0:02:33.480 --> 0:02:36.040 you can never leave, okay. 0:02:36.120 --> 0:02:39.280 According to doctor Commerford, a black hole is basically what 0:02:39.360 --> 0:02:43.560 happens when you squish stuff, matter or energy so much 0:02:43.840 --> 0:02:47.080 that you make a hole in space, and it's a 0:02:47.160 --> 0:02:50.760 three D hole, so it basically looks like a black ball, 0:02:51.200 --> 0:02:55.519 and inside that ball, inside its event horizon, the gravity 0:02:55.680 --> 0:02:59.720 is so strong that nothing, not even light can escape. 0:03:00.280 --> 0:03:02.600 So if you're inside and you shine a laser or 0:03:02.680 --> 0:03:05.840 flashlight to the outside, that light is just going to 0:03:05.919 --> 0:03:10.160 turn around and fall right back in. And to make 0:03:10.160 --> 0:03:14.160 a black hole, according to doctor Commerford, you can squish anything, 0:03:14.600 --> 0:03:17.959 even the Earth. So how much would you have to 0:03:18.000 --> 0:03:20.200 squish the Earth for it to become a black hole? 0:03:20.639 --> 0:03:23.000 So with the Earth, you'd have to squish it down 0:03:23.040 --> 0:03:25.280 and couppress it down all the way to the size 0:03:25.320 --> 0:03:28.639 of a marble, and at that point grabny would win 0:03:28.880 --> 0:03:31.440 and take over and pull all the Earth's mass into 0:03:31.480 --> 0:03:32.120 a black. 0:03:31.840 --> 0:03:34.320 Hole, and the black hole would be the size of 0:03:34.360 --> 0:03:35.000 a marble. 0:03:35.360 --> 0:03:39.480 Well, the event horizon would be the size of a marble. 0:03:40.480 --> 0:03:43.440 And it also works with our sun. If you take 0:03:43.480 --> 0:03:46.240 our sun and squeeze it to roughly the size of Manhattan, 0:03:46.600 --> 0:03:50.080 you'd get a black hole the size of Manhattan. Okay, 0:03:50.200 --> 0:03:53.119 the next question I asked doctor Comerford was how many 0:03:53.160 --> 0:03:57.560 black holes are there out there? So, how many black 0:03:57.600 --> 0:04:00.880 holes are there that we know about? Space just full 0:04:00.920 --> 0:04:02.880 of black holes or is it something that you rarely 0:04:02.920 --> 0:04:04.080 ever run into? 0:04:04.600 --> 0:04:07.240 Oh, spaces full of black holes. So there are two 0:04:07.240 --> 0:04:09.760 main kinds of black holes that we know about. One 0:04:09.840 --> 0:04:12.560 kind is stellar mass black holes. These are the ones 0:04:12.560 --> 0:04:14.960 that are produced at the end of a massive stars 0:04:15.040 --> 0:04:18.360 life effort it explodes in a big supernova explosion, there's 0:04:18.400 --> 0:04:21.000 a stellar mass black hole that's left behind, and they 0:04:21.040 --> 0:04:23.920 have masses similar to the masses of stars. The other 0:04:24.000 --> 0:04:26.000 kind of black hole that we know about are the 0:04:26.040 --> 0:04:29.360 super massive black holes, which have masses millions to billions 0:04:29.400 --> 0:04:32.280 of times more than the mass of a star. And 0:04:32.400 --> 0:04:35.640 typically each galaxy only has one super massive black hole 0:04:35.680 --> 0:04:38.599 and it's sitting at the center of the galaxy. But 0:04:39.080 --> 0:04:42.440 stellar mass black holes can be anywhere there are stars. 0:04:42.640 --> 0:04:45.760 So our galaxy alone, it's got one super massive black 0:04:45.760 --> 0:04:48.360 hole at the center, but it probably has around one 0:04:48.600 --> 0:04:52.520 hundred million stellar mass black holes. Sprinkled throughout the rest 0:04:52.520 --> 0:04:56.159 of the galaxy, one hundred million in our galaxy alone, 0:04:56.160 --> 0:04:57.920 and think about how many billions of galaxies are on 0:04:58.000 --> 0:04:58.520 the universe. 0:04:58.839 --> 0:05:00.760 It seems a little dangerous to for a walk in 0:05:00.760 --> 0:05:01.400 our galaxy. 0:05:01.680 --> 0:05:04.159 You know, black holes get a bad rap whenever someone 0:05:04.160 --> 0:05:08.200 says that they're dangerous. Black holes are like bears. If 0:05:08.240 --> 0:05:11.480 you give them enough distance, they're not going to bother you. 0:05:11.560 --> 0:05:15.800 So black holes are everywhere. The universe is littered with them. 0:05:16.400 --> 0:05:19.480 Okay, here's where I asked her what's inside a black hole? 0:05:20.120 --> 0:05:23.880 Like what happens to all the stuff that falls into them? 0:05:24.400 --> 0:05:26.520 But let's get to the main question of the episode. 0:05:26.560 --> 0:05:28.160 I would say this is it the biggest question when 0:05:28.160 --> 0:05:31.400 I go around to schools talking to kids. That's kind 0:05:31.440 --> 0:05:32.200 of what they want to know. 0:05:32.800 --> 0:05:37.159 That is a great question that is really hard to 0:05:37.240 --> 0:05:40.400 answer because the whole point of a black holes we 0:05:40.480 --> 0:05:43.760 can't peer inside, We can't peer over the event horizon 0:05:43.800 --> 0:05:48.880 and see what's going on inside there. So we have physics, 0:05:48.960 --> 0:05:51.599 We have our understanding of how the universe works, and 0:05:51.600 --> 0:05:54.520 we can try to apply that physics to understand what's 0:05:54.560 --> 0:05:56.480 going on inside a black hole. And people do that, 0:05:56.560 --> 0:05:59.200 write papers about that, but we don't actually know. 0:06:00.520 --> 0:06:04.039 Okay, Like doctor Comerford said, it's very hard to see 0:06:04.080 --> 0:06:07.480 inside a black hole because that's the whole point of 0:06:07.520 --> 0:06:09.880 a black hole. Even if you were to send in 0:06:10.000 --> 0:06:13.600 a robot to look inside a the robot would be 0:06:13.680 --> 0:06:17.040 stuck in there forever and B the robot wouldn't be 0:06:17.120 --> 0:06:20.880 able to send any signals out because the signals would 0:06:20.920 --> 0:06:23.839 also be stuck in there. Remember, not even light can 0:06:23.920 --> 0:06:27.400 get out of a black hole. But as doctor Commerford says, 0:06:27.600 --> 0:06:31.200 we can use science to look inside. We can use 0:06:31.200 --> 0:06:34.720 our theories about how the universe works to reconstruct what's 0:06:34.720 --> 0:06:38.560 going on inside a black hole. Here's how doctor Cumberford 0:06:38.760 --> 0:06:39.400 describes it. 0:06:40.680 --> 0:06:43.040 So what we do know is inside the black hole, 0:06:43.160 --> 0:06:46.880 the force of gravity pulls everything together to one point. 0:06:47.040 --> 0:06:49.160 So all that mass, all that light is going to 0:06:49.279 --> 0:06:52.120 end up at that one infinitely dense point that we 0:06:52.240 --> 0:06:57.080 call the singularity. And there the curvature space time is infinite, 0:06:57.360 --> 0:07:01.320 there's infinite energy density, and so all the known laws 0:07:01.320 --> 0:07:05.359 of physics breakdown. We don't have any existing understanding of 0:07:05.400 --> 0:07:09.479 physics that explains if and it courveragsu're an infinite density. 0:07:09.680 --> 0:07:12.800 Okay, here's what's happening. We have a theory about how 0:07:12.840 --> 0:07:16.880 the universe works called general relativity. You might have heard 0:07:16.880 --> 0:07:19.640 of it. It's one of the things Einstein is famous for, 0:07:20.160 --> 0:07:22.800 and it's a theory that tells us how gravity works 0:07:23.040 --> 0:07:26.840 and how it bends space and time. And the theory 0:07:26.880 --> 0:07:29.239 predicts that when you first go into a black hole, 0:07:29.560 --> 0:07:34.000 when you cross the event horizon, uh, nothing much happens. 0:07:34.600 --> 0:07:37.600 You just keep falling towards the center. So part of 0:07:37.640 --> 0:07:40.800 the answer to what's inside a black hole is that 0:07:40.840 --> 0:07:46.040 it's mostly just space. It's super duper warped space because 0:07:46.040 --> 0:07:49.520 of all the gravity, but it's still just space. So 0:07:49.600 --> 0:07:52.000 most of the time you're inside a black hole, you 0:07:52.080 --> 0:07:56.600 just spend it falling to the center. Are you saying 0:07:56.640 --> 0:07:59.000 that inside a black hole is just more space. 0:07:59.600 --> 0:08:03.200 It's face, but it's space that's really curved. So think 0:08:03.240 --> 0:08:06.880 of like a really steep water slide. You know, it's 0:08:06.920 --> 0:08:09.880 pretty frictionless because there's not a lot of stuff in 0:08:09.920 --> 0:08:13.040 the way to slow down your fall. You'd be falling fast, 0:08:13.520 --> 0:08:15.880 but there wouldn't be much to bump into because everything 0:08:15.920 --> 0:08:19.360 that's fallen in before you has ended up at the singularity. 0:08:19.840 --> 0:08:21.960 What you're calling this singularity, which is where all the 0:08:22.000 --> 0:08:27.240 stuff that's in a black hole accumulates. That's right, all right, 0:08:27.360 --> 0:08:30.760 This is where it gets really interesting. At the center 0:08:30.840 --> 0:08:34.559 of a black hole is what scientists call the singularity, 0:08:34.880 --> 0:08:37.839 and this is where the really crazy stuff happens. As 0:08:37.880 --> 0:08:41.160 you'll hear from our experts in that singularity could be 0:08:41.520 --> 0:08:44.960 the end of time, or a portal to another universe, 0:08:45.400 --> 0:08:50.240 or maybe even a universe factory. So when we come back, 0:08:50.480 --> 0:08:52.640 we'll talk to our next expert and hear what he 0:08:52.760 --> 0:08:57.360 thinks is inside the inside of a black hole. Stay 0:08:57.400 --> 0:09:10.960 with us, you're listening to sign stuff. Welcome back, Okay. 0:09:11.200 --> 0:09:13.920 Like I said, I talked to three black hole experts, 0:09:14.200 --> 0:09:16.920 and they each gave me a different answer about what's 0:09:16.920 --> 0:09:20.360 inside a black hole. The next person I talked to 0:09:20.559 --> 0:09:24.480 was someone who specializes in the interior of black holes. 0:09:26.360 --> 0:09:29.600 So I'm doctor Tyler McMackin, and I'm a professor of 0:09:29.600 --> 0:09:32.720 physics at the University of Mary So I teach physics 0:09:32.760 --> 0:09:35.400 and I research the interiors of black holes. 0:09:35.920 --> 0:09:40.120 Fantastic, that is the perfect specialty for episode today. And 0:09:40.160 --> 0:09:43.920 you've written several papers on this topic. Actually, what are 0:09:43.920 --> 0:09:45.360 we going to find inside of a black hole? 0:09:45.720 --> 0:09:49.840 Well, it's a good question. There's essentially three different theories 0:09:50.080 --> 0:09:54.440 of what happens inside black holes. First is a portal 0:09:54.480 --> 0:09:58.800 to another universe, the second is some exotic ball of matter, 0:09:59.360 --> 0:10:02.440 and then the third is something we call a singularity, 0:10:02.840 --> 0:10:05.880 which is basically a brick wall where space and time 0:10:05.920 --> 0:10:08.320 itself comes to an unavoidable end. 0:10:09.200 --> 0:10:13.440 Okay, WHOA, that's a lot to digest. Doctor McMackin has 0:10:13.480 --> 0:10:15.600 three ideas for what could be at the center of 0:10:15.640 --> 0:10:18.400 a black hole, so we'll take them one at a time. 0:10:18.840 --> 0:10:21.040 The first one is that at the center of a 0:10:21.080 --> 0:10:25.079 black hole is a portal to another universe. 0:10:26.640 --> 0:10:29.760 Yeah, so for this first idea, there is a portal 0:10:29.840 --> 0:10:33.360 to a new universe. This goes back to the early 0:10:33.480 --> 0:10:36.800 days of when people were first discovering the equations that 0:10:36.800 --> 0:10:40.880 describe black holes. The scientist named Roy Patrick Kerr, he 0:10:40.920 --> 0:10:43.720 was a New Zealander in the nineteen sixties, came up 0:10:43.760 --> 0:10:47.280 with a model that allows for both a black hole 0:10:47.360 --> 0:10:51.200 and a white hole to exist simultaneously. The idea would 0:10:51.240 --> 0:10:54.040 basically be, we fall into the black hole. Once we 0:10:54.080 --> 0:10:57.000 get to the center, then we just go through the 0:10:57.080 --> 0:10:59.800 drain or whatever analogy want to use, and then pop 0:10:59.920 --> 0:11:00.640 up the other side. 0:11:01.840 --> 0:11:05.040 Okay, what doctor mcmackinn is saying is that the equations 0:11:05.040 --> 0:11:08.880 for a black hole also predict something called a white hole, 0:11:09.320 --> 0:11:12.640 which is the opposite of a black hole. So if 0:11:12.640 --> 0:11:15.000 a black hole is a place where stuff falls in 0:11:15.320 --> 0:11:18.200 and can never get out, a white hole is a 0:11:18.200 --> 0:11:21.880 place that constantly throws out stuff and nothing can ever 0:11:22.240 --> 0:11:26.120 go in. It's like a three D cosmic fountain, which 0:11:26.160 --> 0:11:28.840 is the opposite of a hole. So if you fall 0:11:28.880 --> 0:11:31.160 into a black hole and you get to the middle 0:11:31.280 --> 0:11:33.960 and somewhat made it through the singularity, you would come 0:11:34.000 --> 0:11:38.800 out of a white hole somewhere else where. 0:11:39.320 --> 0:11:41.720 Well, it can be basically wherever you want it to be, 0:11:41.760 --> 0:11:45.040 so it'll be a whole new universe. And some people 0:11:45.200 --> 0:11:47.840 have imagined that it could lead to somewhere else in 0:11:47.880 --> 0:11:51.679 our current universe or some when else in our current universe. 0:11:53.360 --> 0:11:55.960 Yes, that's right. This wormhole could not just take you 0:11:56.000 --> 0:11:58.800 to another part of the universe. It could also take 0:11:58.840 --> 0:12:02.199 you to another top I'm in the universe. You could 0:12:02.679 --> 0:12:05.680 time travel, or it could even take you to a 0:12:05.679 --> 0:12:11.120 whole other universe. But it could be a different universe. 0:12:11.240 --> 0:12:13.360 What does that even mean? Another universe? 0:12:13.760 --> 0:12:16.160 Yeah, I guess it really means that there's no way 0:12:16.240 --> 0:12:19.720 of getting back to where you were originally. So it's 0:12:19.760 --> 0:12:23.960 completely causally disconnected from the current universe that we have. 0:12:24.080 --> 0:12:27.280 We can't communicate by sending light signals from one to 0:12:27.320 --> 0:12:27.640 the other. 0:12:28.040 --> 0:12:30.200 Huh, like a whole different reality. 0:12:30.800 --> 0:12:33.640 Yeah, anything is possible, I suppose. Yeah. 0:12:33.720 --> 0:12:37.000 So then the other universe does it exist somewhere else 0:12:37.160 --> 0:12:39.719 and we're just kind of using the black hole as 0:12:39.760 --> 0:12:40.319 a tunnel. 0:12:41.040 --> 0:12:42.720 Yeah, I guess it would be better to think of 0:12:42.760 --> 0:12:45.480 it as we're using the black hole as a bridge 0:12:45.640 --> 0:12:48.560 between the two universes. So that's why it's often called 0:12:48.600 --> 0:12:49.240 a wormhole. 0:12:49.360 --> 0:12:52.400 Would this other universe be like the opposite of our universe? 0:12:53.040 --> 0:12:55.319 It doesn't have to be. It's just not necessarily like, oh, 0:12:55.360 --> 0:12:57.760 there's this parallel universe where you have an evil twin 0:12:57.880 --> 0:12:58.559 or something. 0:12:58.320 --> 0:13:01.760 Like that, Doctor McMackin. Assuming I'm not the evil twin. 0:13:02.880 --> 0:13:06.199 Yes, we are all the evil twins. The other universe 0:13:06.280 --> 0:13:06.959 is the normal one. 0:13:07.040 --> 0:13:11.120 Right, So that's one thing that the laws of physics 0:13:11.200 --> 0:13:14.480 predict could be inside a black hole. And here I 0:13:14.480 --> 0:13:17.360 should mention this is for a perfectly still black hole. 0:13:17.720 --> 0:13:20.360 We'll get more into that later. But the second thing 0:13:20.440 --> 0:13:22.560 doctor Meke Becken said could be at the center of 0:13:22.600 --> 0:13:28.840 a black hole is a ball of exotic matter, a ball. 0:13:28.600 --> 0:13:33.200 Of y, a ball of exotic matter. The more likely 0:13:33.240 --> 0:13:37.920 outcome is that instead of this infinitely long, dense drain 0:13:38.240 --> 0:13:41.680 at the center, this is replaced by some currently unknown 0:13:41.840 --> 0:13:46.280 process that will stop the collapse and just form a ball. 0:13:46.400 --> 0:13:49.680 Maybe it's some sort of quantum star or something like that. 0:13:49.679 --> 0:13:53.200 A quantum star that sounds like a great name for 0:13:53.559 --> 0:13:59.240 superhero franchise. I agree, what is a quantum star? All right, 0:13:59.280 --> 0:14:02.360 here's doctor Backin's second idea. At the center of a 0:14:02.400 --> 0:14:04.800 black hole, where all the stuff that fell into the 0:14:04.840 --> 0:14:08.160 black hole is coming together and scrunching together, there is 0:14:08.200 --> 0:14:11.600 something that is keeping all that stuff from becoming an 0:14:11.679 --> 0:14:16.439 infinitely dense point. There's some kind of quantum force that's 0:14:16.520 --> 0:14:19.840 preventing all that stuff from collapsing, and so it creates 0:14:19.880 --> 0:14:22.720 a ball that just sits there in the middle of 0:14:22.760 --> 0:14:25.600 the black hole. So it'd just be sort of like 0:14:25.680 --> 0:14:28.600 pure matter or energy. It just as pure as you 0:14:28.600 --> 0:14:30.480 can get it, because it wouldn't be in the form 0:14:30.520 --> 0:14:32.280 of electrons or quarks or anything. 0:14:32.720 --> 0:14:37.760 Right, Yeah, something strings squanto phoam. There are tons of 0:14:37.760 --> 0:14:38.920 different theories. 0:14:39.080 --> 0:14:41.360 And this would be like at the very center, or 0:14:41.360 --> 0:14:42.960 as soon as we go into the black hole, we 0:14:43.000 --> 0:14:44.359 would run into this ball. 0:14:44.560 --> 0:14:46.560 So it would be at the very center. 0:14:47.040 --> 0:14:52.720 Yes, okay, this gets into one of the ultimate frontiers 0:14:52.800 --> 0:14:56.400 of science, and that is mixing together the two most 0:14:56.440 --> 0:14:59.760 successful theories in the history of our understanding of the 0:15:00.000 --> 0:15:03.920 physical world. On the one hand, we have general relativity, 0:15:04.280 --> 0:15:08.320 Einstein's theory that predicted black holes, that predicts that at 0:15:08.320 --> 0:15:11.400 the center of a perfectly still black hole is a 0:15:11.440 --> 0:15:14.680 point of infinite density that could be a wormhole to 0:15:14.760 --> 0:15:19.240 another universe. And on the other hand, we have quantum mechanics, 0:15:19.440 --> 0:15:21.520 the theory that tells you that when you get down 0:15:21.560 --> 0:15:24.920 to the level of super small atoms and particles, things 0:15:24.960 --> 0:15:27.560 are kind of fuzzy and you can't really have points 0:15:27.600 --> 0:15:31.640 with infinite density. So, depending on whose right, at the 0:15:31.680 --> 0:15:34.120 center of a black hole could be a point of 0:15:34.160 --> 0:15:37.640 infinite density, or there could be some sort of strange 0:15:37.760 --> 0:15:40.920 or exotic quantum force that keeps all that stuff from 0:15:40.920 --> 0:15:44.360 collapsing and forms. And I still love this name, a 0:15:44.480 --> 0:15:48.800 quantum star at the center of a black hole. Scientists 0:15:48.800 --> 0:15:51.720 don't really know which is true. 0:15:54.600 --> 0:15:57.600 We don't currently have a theory for how those two 0:15:58.080 --> 0:16:02.520 theories combined together to make one consistent model. And so 0:16:02.880 --> 0:16:05.160 people are searching for this and that it goes under 0:16:05.200 --> 0:16:08.080 the general name of quantum gravity, and so you need 0:16:08.120 --> 0:16:11.440 a full theory of quantum gravity to figure out what's happening. 0:16:12.160 --> 0:16:12.560 All right. 0:16:12.840 --> 0:16:16.080 The third idea doctor Magneckin had is something he calls 0:16:16.240 --> 0:16:20.760 a wall or time and space end. And this is 0:16:20.760 --> 0:16:23.200 something that comes up when you think about what black 0:16:23.240 --> 0:16:27.760 holes are actually like out there in nature. Remember, I said, 0:16:27.800 --> 0:16:30.120 a lot of the ideas we talked about assume the 0:16:30.160 --> 0:16:33.360 black hole was perfectly still and not moving. It turns 0:16:33.360 --> 0:16:35.520 out that's rarely the case. 0:16:37.080 --> 0:16:39.280 I would say, all of the objects that we see 0:16:39.440 --> 0:16:42.880 in the universe have spin. So everything from planets to 0:16:42.960 --> 0:16:46.280 stars to galaxies has at least some amount of rotation, 0:16:46.800 --> 0:16:49.280 and so we expect that black holes will also have 0:16:49.360 --> 0:16:52.800 some sort of spin to them as well. Then, because 0:16:52.840 --> 0:16:56.320 it's spinning, the Singularity doesn't look like a point anymore. 0:16:56.720 --> 0:16:59.600 It looks like a ring, which is really weird to 0:16:59.600 --> 0:17:00.520 think about. 0:17:01.440 --> 0:17:06.439 Okay, here's what's happening. Nothing in space is really standing still. 0:17:07.000 --> 0:17:11.680 Almost everything out there is spinning. Planet spin, stars and 0:17:11.800 --> 0:17:16.320 sun spin moons, asteroids, even clouds of gas and galaxies. 0:17:16.720 --> 0:17:20.040 They're all turning to some degree. And the same is 0:17:20.040 --> 0:17:23.280 true for black holes. And if a black hole is spinning, 0:17:23.680 --> 0:17:26.359 that means that everything inside of it is spinning, and 0:17:26.400 --> 0:17:29.320 that makes the center of the black hole act like 0:17:29.359 --> 0:17:30.800 a merry go round. 0:17:32.280 --> 0:17:34.680 So if your black hole is spinning a little bit, 0:17:35.160 --> 0:17:38.240 then you get this thing, which we could call a 0:17:38.280 --> 0:17:41.760 centric fugal for us, things that are spinning tend to 0:17:41.760 --> 0:17:46.000 get flung outwards, and so that provides this outward force 0:17:46.040 --> 0:17:49.200 that pushes against the flow of space. So that must 0:17:49.200 --> 0:17:52.360 mean there's some point where the speed of the thing 0:17:52.400 --> 0:17:57.800 that you threw outward matches the inflowing speed of the 0:17:57.840 --> 0:18:01.680 space itself. That's going to happen a special spot called 0:18:01.680 --> 0:18:02.360 the ener horizon. 0:18:04.280 --> 0:18:07.600 Okay, this gets a little complicated, but it's like if 0:18:07.640 --> 0:18:10.679 a thousand people were all trying to ride a merry 0:18:10.680 --> 0:18:13.959 go round, but the merry go round was spinning really fast, 0:18:14.520 --> 0:18:17.360 the merry go round would be flinging people out at 0:18:17.359 --> 0:18:20.160 the same time that people were trying to get on it, 0:18:20.800 --> 0:18:23.639 So you'd get this ring around the merry go round 0:18:23.720 --> 0:18:27.639 where people would just pile up. The same thing happens 0:18:27.680 --> 0:18:30.880 in a rotating black hole, but with space. 0:18:32.600 --> 0:18:34.760 All of this debrie that ever fell into the black 0:18:34.760 --> 0:18:39.200 hole gets caught up in this one part, and eventually 0:18:39.200 --> 0:18:42.479 we might imagine that it blocks up the flow of 0:18:42.520 --> 0:18:46.440 the space itself. And if you then were to try 0:18:46.560 --> 0:18:49.280 to fall into the black hole after that, you would 0:18:49.359 --> 0:18:53.359 just hit this brick wall where all of this mass 0:18:53.440 --> 0:18:57.000 stuff has just built up and accumulated. So this is 0:18:57.040 --> 0:18:59.679 what we call a singularity, where we have basically an 0:18:59.720 --> 0:19:03.879 infant amount of energy that signals the end of space 0:19:03.920 --> 0:19:05.600 itself and the end of time itself. 0:19:06.359 --> 0:19:08.880 So this singularity is not singular. 0:19:08.760 --> 0:19:10.120 It's a whole surface. 0:19:10.280 --> 0:19:12.639 Yeah, maybe you should pick another name for it. 0:19:12.800 --> 0:19:16.360 That is a good point. Do you have any suggestions? 0:19:16.400 --> 0:19:17.399 I'm open, I'm all. 0:19:17.280 --> 0:19:23.119 Ears, okay to recap Here are the three possibilities for 0:19:23.280 --> 0:19:25.960 what's at the center of a black hole, according to 0:19:26.040 --> 0:19:29.920 doctor mcmackinn Number one. If it's a perfect black hole, 0:19:30.280 --> 0:19:33.240 there could be a point of infinite density at the 0:19:33.280 --> 0:19:36.320 center of the black hole, which could potentially be the 0:19:36.520 --> 0:19:40.040 entrance to a wormhole that connects to a white hole 0:19:40.240 --> 0:19:45.120 somewhere else in another time or maybe even in another universe. 0:19:45.880 --> 0:19:50.760 Possibility Number two. If quantum mechanics wins at the smallest levels, 0:19:51.160 --> 0:19:54.159 then some kind of quantum force which we don't know 0:19:54.200 --> 0:19:57.200 about yet, could keep all this stuff inside a black 0:19:57.240 --> 0:20:01.080 hole from collapsing into an infinite point. And then you'd 0:20:01.080 --> 0:20:04.720 have a ball of exotic quantum matter or a quantum 0:20:04.760 --> 0:20:07.560 star just sitting in the middle of a black hole, 0:20:07.840 --> 0:20:12.000 shining a light that will never get out. And possibility 0:20:12.080 --> 0:20:15.760 number three. If it's a realistic black hole, which means 0:20:15.800 --> 0:20:19.000 it's spinning, then that spinning could also prevent the black 0:20:19.040 --> 0:20:22.480 hole from collapsing into an infinite dot, and you'd get 0:20:22.480 --> 0:20:26.280 a ring where stuff accumulates and where time and space 0:20:26.640 --> 0:20:32.080 just stop. Phe I told you this got crazier and crazier. 0:20:32.480 --> 0:20:35.119 And we haven't even gotten to our third expert. So 0:20:35.240 --> 0:20:38.879 when we come back, we'll talk to another theoretical astrophysicist 0:20:39.200 --> 0:20:42.360 who has an even wilder prediction for what could be 0:20:42.520 --> 0:20:45.920 at the center of a black hole. So don't go anywhere. 0:20:46.280 --> 0:20:49.360 Keep spinning with us as we go deeper and deeper 0:20:49.480 --> 0:20:50.880 into black holes. 0:20:51.480 --> 0:20:52.400 We'll be right back. 0:21:00.880 --> 0:21:04.880 Okay, we've now reached the deepest level of black hole mystery. 0:21:05.320 --> 0:21:09.240 We've talked about several wild but still theoretically possible ideas 0:21:09.520 --> 0:21:12.000 about what could be at the center of a black hole, 0:21:12.560 --> 0:21:17.400 from quantum stars to wormholes, to other universes, to walls 0:21:17.440 --> 0:21:21.840 of infinite density where time and space end. But this 0:21:22.000 --> 0:21:26.160 next idea might take the cake as being the craziest, 0:21:26.560 --> 0:21:29.840 and it came up during my chat with Professor Andrew Hamilton. 0:21:30.160 --> 0:21:32.879 Doctor Hamilton is also a professor at the University of 0:21:32.920 --> 0:21:37.080 Colorado at Boulder who studies theoretical astrophysics and in particular, 0:21:37.240 --> 0:21:42.040 the insides of black holes. Thank you, doctor Hamilton for 0:21:42.119 --> 0:21:44.199 joining us today, No problem, Thank you. 0:21:44.440 --> 0:21:44.640 Hey. 0:21:44.960 --> 0:21:47.679 Today we're answering the question what is inside of a 0:21:47.720 --> 0:21:51.119 black hole? What can you tell us about what's inside? 0:21:51.480 --> 0:21:55.680 Oh, this is the most interesting place in the entire universe. 0:21:56.720 --> 0:21:59.160 Uh huh, there's a challenging statement to make. 0:21:59.520 --> 0:21:59.920 Yeah. 0:22:00.320 --> 0:22:02.399 Well, first of all, I have to give you a 0:22:02.400 --> 0:22:06.560 little bit of background on this. Even today, there's certain 0:22:06.600 --> 0:22:09.399 amount of debate as to what happens. So I'm going 0:22:09.480 --> 0:22:11.920 to give you a version which I think is probably 0:22:11.960 --> 0:22:14.520 the most realistic view of what happens. 0:22:14.720 --> 0:22:18.840 Okay, okay, In the scenario that doctor Hamilton is about 0:22:18.840 --> 0:22:21.639 to describe, we're assuming that at the center of the 0:22:21.640 --> 0:22:25.720 black hole is the singularity ring we talked about before. 0:22:26.080 --> 0:22:28.879 That's the point where the centerfical force of the spinning 0:22:28.920 --> 0:22:32.240