WEBVTT - How fast can a black hole spin?

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<v Speaker 1>Hey, Daniel, would you say you understand general relativity?

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<v Speaker 2>I mean i'd say I understand it better.

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<v Speaker 1>Every week, so that means you don't understand it.

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<v Speaker 2>I think it still like makes my head spin.

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<v Speaker 1>To be honest, what's the trickiest part of it?

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<v Speaker 2>I think the hardest part to get your mind around

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<v Speaker 2>is that spinning stuff has different gravity than stuff that

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<v Speaker 2>doesn't spin.

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<v Speaker 1>Yeah, okay, there's no way to spend that. That is

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<v Speaker 1>just confusing.

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<v Speaker 2>Sometimes I just want to like spin up extra brains

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<v Speaker 2>to help me figure out how space itself can spin.

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<v Speaker 1>That is quite a yarn you are spinning.

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<v Speaker 2>Maybe I'm spinning a web of physics or a web

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<v Speaker 2>of lies.

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<v Speaker 1>I'll take that for a spin.

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<v Speaker 2>Hi, I'm Daniel. I'm a particle physicist and a professor

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<v Speaker 2>at uc Irdine, And those are all the spin related

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<v Speaker 2>jokes I could think of.

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<v Speaker 1>Hi, I'm Katie, and I cannot put a new spin

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<v Speaker 1>on those jokes. I am not a particle physicist, but

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<v Speaker 1>I enjoy physics in the universe and I host an

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<v Speaker 1>animal themed podcast.

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<v Speaker 2>All right, I got one more spin related joke for

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<v Speaker 2>you. You ready, wait?

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<v Speaker 1>Wait, okay, now I'm ready.

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<v Speaker 2>Why did scientists stop watching the Earth spin.

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<v Speaker 1>I don't know, Daniel why they.

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<v Speaker 2>Got bored and called it a day.

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<v Speaker 1>Oh that's my soul leaving my body.

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<v Speaker 2>That was a good one, and Welcome to the podcast

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<v Speaker 2>Daniel and Jorge explain the Universe, in which we try

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<v Speaker 2>to avoid your brain spinning inside your cranium as we

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<v Speaker 2>take a tour of how the universe works, all of

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<v Speaker 2>its weird and wonderful ways of operating, from the tiniest

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<v Speaker 2>quantum particles to the most massive of super massive black

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<v Speaker 2>holes spinning at the centers of galaxies. Motion and rotation

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<v Speaker 2>and spinning and translation, and all of these things are

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<v Speaker 2>essential to the way the universe works in some sense.

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<v Speaker 2>Understanding how things move and what they are is what

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<v Speaker 2>physics is all about. That's what we try to do

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<v Speaker 2>on this podcast, break down why things move, how they spin,

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<v Speaker 2>and how that affects everything around them. My friend and

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<v Speaker 2>co host Orge can be with us today, but we're

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<v Speaker 2>very happy to have Katie here with us to take

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<v Speaker 2>physics for a spin.

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<v Speaker 1>You know, I used to do ballet when I was

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<v Speaker 1>a kid, and one of the things you have to

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<v Speaker 1>learn to do in ballet is to spin without getting

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<v Speaker 1>dizzy and falling over and so you kind of try

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<v Speaker 1>to keep your head looking at a point of reference

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<v Speaker 1>and sort of twist your head around so that you

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<v Speaker 1>don't get dizzy. Are you saying that when I'm a ballerina,

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<v Speaker 1>I have more gravity than regular non ballerinas.

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<v Speaker 2>I'm saying when you do that spin, you drag the

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<v Speaker 2>fabric of space time along with you, like sticking a

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<v Speaker 2>fork in spaghetti and twisting it.

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<v Speaker 1>That's really cool. Now, I wonder my teacher was so

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<v Speaker 1>strict she didn't want us tearing holes in the fabric

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<v Speaker 1>of the universe with our off tempo spins.

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<v Speaker 2>She was really just looking out for your safety, it

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<v Speaker 2>sounds like. And as scientists have tried to understand the

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<v Speaker 2>nature of gravity, why things fall down, why things orbit

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<v Speaker 2>each other in the sky, we have learned so much

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<v Speaker 2>about the very nature of the universe around us. From

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<v Speaker 2>Aristotle just telling us things fall down because they like

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<v Speaker 2>sort of going down, to Newton telling us that gravity

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<v Speaker 2>is a force between objects that have mass, to Einstein

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<v Speaker 2>telling us that actually gravity is the bending of space,

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<v Speaker 2>invisibly curving in front of us and affecting the path

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<v Speaker 2>of everything that moves through it every time. It requires

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<v Speaker 2>a huge conceptual change in the way the universe works

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<v Speaker 2>around us, often with surprising results and strange phenomena that

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<v Speaker 2>really test our ability to un understand the nature of

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<v Speaker 2>the universe.

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<v Speaker 1>Do we now understand what gravity is like? Has that

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<v Speaker 1>answer been solved for good?

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<v Speaker 2>We're going to solve it today on the podcast Katie

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<v Speaker 2>that's right.

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<v Speaker 1>Oh, let me get out of notepad.

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<v Speaker 2>After this podcast, buy your ticket to Stockholm. No, gravity

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<v Speaker 2>is definitely not understood. In fact, we know that our

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<v Speaker 2>current understanding of gravity is limited, that there are parts

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<v Speaker 2>of the universe it just fails to describe, and parts

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<v Speaker 2>of the history of the universe that just don't make

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<v Speaker 2>sense if you take literally Einstein's theory of general relativity.

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<v Speaker 2>And one of those places is at the heart of

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<v Speaker 2>black holes. Black holes are famous because they're weird and

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<v Speaker 2>they gobble stuff up, and yet they actually exist in

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<v Speaker 2>the universe. But they hold within them mysteries and secrets

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<v Speaker 2>that might tell us how gravity actually works at the

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<v Speaker 2>quantum mechanical level. The thing that we don't know how

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<v Speaker 2>to do is merge Einstein's picture of gravity with the

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<v Speaker 2>way quantum mechanics tells us that reality operates at the

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<v Speaker 2>smallest level. Because we can't go so inside black holes.

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<v Speaker 2>We have to do other things to them. And one

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<v Speaker 2>thing we can do to black holes is to spin

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<v Speaker 2>them and see what happens when they stick their fork

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<v Speaker 2>into the spaghetti of space time.

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<v Speaker 1>Okay, when you say we can spin black holes, do

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<v Speaker 1>you mean we can just sort of twirl them around

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<v Speaker 1>like a giant top or something, or a huge destructive

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<v Speaker 1>bay blade. Are these things just out there naturally spinning

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<v Speaker 1>or are we shooting ping pong balls at them to

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<v Speaker 1>try to get them to spin both?

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<v Speaker 2>Actually, all the black holes we know about are too

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<v Speaker 2>far away for us to experiment on in the laboratory.

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<v Speaker 2>There aren't any very close by. But we do think

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<v Speaker 2>that all of the black holes that exist in the

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<v Speaker 2>universe do spin. Basically, everything out there is spinning. Our

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<v Speaker 2>planet is spinning, the Sun is spinning, Our planet spins

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<v Speaker 2>around the Sun. The Sun spins around the center of

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<v Speaker 2>the galaxy. The galaxy orbits the center of the galactic cluster. Basically,

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<v Speaker 2>everything out there is spinning, and because angular momentum in

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<v Speaker 2>the universe is conserved, we think that everything that went

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<v Speaker 2>into the black hole was probably spinning. So the black

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<v Speaker 2>holes themselves are almost certainly spinning, which means every black

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<v Speaker 2>hole out there is probably a spinning object. And the

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<v Speaker 2>fascinating thing about spinning a black hole is that it

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<v Speaker 2>changes its gravity. But there's a catch. Black holes can

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<v Speaker 2>only spin so fast before they might tear themselves open.

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<v Speaker 1>I mean that's also true in ballet. So the Earth

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<v Speaker 1>is spinning? Is that why the Earth has gravity? And

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<v Speaker 1>it keeps us on it?

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<v Speaker 2>The Earth would have gravity even if it wasn't spinning.

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<v Speaker 2>But the Earth's gravity is actually subtly different because it

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<v Speaker 2>does spin. It doesn't just pull on things, It also

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<v Speaker 2>twists things in orbit around it. We'll dig into all

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<v Speaker 2>that when we talk about frame dragging. But because spinning

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<v Speaker 2>of an object changes its gravity, it can also affect

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<v Speaker 2>the size of a black hole and puts a limit

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<v Speaker 2>on how fast a black hole is allowed to spin

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<v Speaker 2>before it cracks open and breaks the rules of physics.

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<v Speaker 1>Wait, so can a black hole actually crack open? Or

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<v Speaker 1>is the just some kind of theoretical limit.

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<v Speaker 2>The rules of physics actually say that there's a maximum

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<v Speaker 2>speed that black holes are allowed to spin before they

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<v Speaker 2>crack open. Nobody knows what would happen if you broke

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<v Speaker 2>that rule. Would it actually crack open the black hole?

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<v Speaker 2>Would you go to physics jail Kai's old ballet teacher

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<v Speaker 2>come and scold you. Let's find out.

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<v Speaker 1>Oh, that's the scariest option.

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<v Speaker 2>And so today on the podcast, we'll be answering the

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<v Speaker 2>question how fast can a black hole spin?

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<v Speaker 1>I'm gonna say fifty miles per hour? I get it.

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<v Speaker 2>Don't tell me that's the fastest speed you can imagine

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<v Speaker 2>in your mind, Kitty, you live in Italy. The drivers

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<v Speaker 2>there drive faster than that all the time, just when

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<v Speaker 2>they're going to the corner store.

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<v Speaker 1>I guess, but it's in kilometers per hour, and I

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<v Speaker 1>haven't figured that out yet.

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<v Speaker 2>How long you've been there already?

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<v Speaker 1>You know, a couple kilometers? I'm not really sure.

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<v Speaker 2>Right, We won't quiz you on you, but I did

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<v Speaker 2>go out there and ask our listeners what they thought

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<v Speaker 2>about how fast a black hole could spin. We're very

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<v Speaker 2>grateful to the listeners who participate in this segment of

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<v Speaker 2>the podcast, giving us a sense for what people know

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<v Speaker 2>and what they're confused about. If you would be willing

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<v Speaker 2>to add your voice to this group of volunteers, please

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<v Speaker 2>don't be shy. Write to me to questions at danielandthork

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<v Speaker 2>dot com. So think about it for a moment before

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<v Speaker 2>you hear these answers. Do you know how fast a

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<v Speaker 2>black hole can spin? Here's what people had to say.

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<v Speaker 1>Faster than sonic the hedgehog.

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<v Speaker 3>I would guess up to the speed of light. I

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<v Speaker 3>think nothing can go faster than that through space, so

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<v Speaker 3>that would be a limit. But I don't see any

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<v Speaker 3>reason why it couldn't get up to that speed.

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<v Speaker 2>I actually learned that black hole spain the other day.

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<v Speaker 4>I have no idea how fast they go. I believe

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<v Speaker 4>that the rate of rotation of a black hole has

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<v Speaker 4>to do with its size, so the smaller ones will

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<v Speaker 4>rotate faster. How fast can they go? I have no idea.

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<v Speaker 5>Well, I would assume that they spin very fast, because

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<v Speaker 5>neutron stars such as pulsars spin I believe many thousand

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<v Speaker 5>times per minute, and black holes are perhaps even smaller

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<v Speaker 5>and denser, which the contraction of their size would make

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<v Speaker 5>them spin even faster, just like a figure skater holding

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<v Speaker 5>their arms in would make them spin faster.

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<v Speaker 6>My instinct is that the only limit ON have asked

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<v Speaker 6>a black hole could spin is the speed of light. However,

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<v Speaker 6>I imagine there might be some kind of loophole that

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<v Speaker 6>may allow it to be faster than that.

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<v Speaker 7>Very intrigued, Well, black holes, you mean the thing that

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<v Speaker 7>makes the black hole or the stuff going into the

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<v Speaker 7>black hole, Because the stuff going into the black hole

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<v Speaker 7>can spin really fast, but this thing that is the

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<v Speaker 7>black hole is the singularity, and can a singularity even

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<v Speaker 7>spin I don't even know.

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<v Speaker 2>I don't even understand what a singularity is. Mass that's

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<v Speaker 2>been infinitely mashed up.

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<v Speaker 8>Black holes would not spin so fast that any given

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<v Speaker 8>part would have such a high angular momentum to fly

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<v Speaker 8>off the black hole. But being such massive bodies, they

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<v Speaker 8>can spin really fast.

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<v Speaker 1>I do enjoy the Sonic the Hedgehog answer that it

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<v Speaker 1>could be even faster than Sonic the Hedgehog, who probably

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<v Speaker 1>does spin faster than fifty miles per hour, Like, would

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<v Speaker 1>you say that a black hole is faster than mister

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<v Speaker 1>Sonic the Hedgehog.

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<v Speaker 2>You know, I've been asked a lot of physics questions

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<v Speaker 2>in my career, a lot of random questions from the public.

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<v Speaker 2>I've never been asked to compare a black hole to

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<v Speaker 2>a fictional video game character, and I just don't know

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<v Speaker 2>how to answer that question. Like the Sonic the Hedgehog

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<v Speaker 2>even follow the laws of physics. Are the two things

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<v Speaker 2>comparable at all? Or is it like comparing miles per

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<v Speaker 2>hour to kilometer per second?

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<v Speaker 1>Wise answer given how many Sonic the Hedgehog fans are

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<v Speaker 1>out there ready for blood. But yeah, I mean, it

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<v Speaker 1>seems like some people think it's limited by the speed

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<v Speaker 1>of light, and so some people think that it's got

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<v Speaker 1>to be faster than something like a bigger skater, or

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<v Speaker 1>smaller things rotate faster, or a lot of really interesting

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<v Speaker 1>theories from people.

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<v Speaker 2>Yeah, and people are definitely right that the surface of

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<v Speaker 2>a black hole shouldn't be able to move faster than

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<v Speaker 2>the speed of light. But it turns out there's another

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<v Speaker 2>limitation to black hole speeds that if black holes spin

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<v Speaker 2>too fast, they might crack open and reveal what's inside

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<v Speaker 2>of them. So it's a fascinating question to think about,

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<v Speaker 2>like what is a black hole, how do they spin,

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<v Speaker 2>how fast do they spin? What is the maximum speed?

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<v Speaker 2>And what would happen if you overspun a black hole.

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<v Speaker 1>It's like if you spun pizza dough too fast and

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<v Speaker 1>it tore itself apart. But I did think black holes

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<v Speaker 1>weren't so much a physical object like a pizza. I

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<v Speaker 1>thought it was kind of this just sort of sinkhole

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<v Speaker 1>in the universe of like of incredibly incredib dovidibly dense

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<v Speaker 1>matter that has an incredibly strong pull of gravity. I

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<v Speaker 1>could use a refresher on what exactly a black hole

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<v Speaker 1>is made out of.

0:12:09.160 --> 0:12:11.400
<v Speaker 2>Black Holes are both physical objects and that we know

0:12:11.640 --> 0:12:14.680
<v Speaker 2>there's something inside of them. There's some mass in there,

0:12:15.120 --> 0:12:17.920
<v Speaker 2>but there's also a sort of conceptual layer to them,

0:12:18.360 --> 0:12:20.360
<v Speaker 2>which is the event horizon. Then we'll talk about in

0:12:20.360 --> 0:12:22.160
<v Speaker 2>a minute, But in the beginning, it just starts with

0:12:22.200 --> 0:12:25.640
<v Speaker 2>a blob of stuff. You know, stuff has gravity, but

0:12:25.679 --> 0:12:28.760
<v Speaker 2>gravity is sort of surprisingly weak, like it's the weakest

0:12:28.800 --> 0:12:32.360
<v Speaker 2>fundamental force that's out there. Gravity is so much weaker

0:12:32.400 --> 0:12:35.600
<v Speaker 2>than like electromagnetism or the weak nuclear force or the

0:12:35.640 --> 0:12:38.520
<v Speaker 2>strong force. And you can discover this yourself. Every time

0:12:38.559 --> 0:12:40.720
<v Speaker 2>you put like a fridge magnet up on the fridge,

0:12:40.960 --> 0:12:44.160
<v Speaker 2>that tiny little magnet is holding it up. It's beating

0:12:44.200 --> 0:12:48.320
<v Speaker 2>the gravity of the entire Earth. Right, This enormous planet

0:12:48.559 --> 0:12:50.720
<v Speaker 2>with all of its rocks and magma inside of it

0:12:50.760 --> 0:12:53.959
<v Speaker 2>is pulling on that thing, defeated by a tiny fridge magnet.

0:12:54.120 --> 0:12:57.040
<v Speaker 2>That tells you how a weak gravity really is, and

0:12:57.120 --> 0:13:01.840
<v Speaker 2>yet if you accumulate enough mass, gravity can become pretty powerful.

0:13:01.880 --> 0:13:04.840
<v Speaker 2>I mean it's holding you to the surface. The Sun's

0:13:04.920 --> 0:13:08.440
<v Speaker 2>gravity is holding the entire Earth in orbit, right, the

0:13:08.480 --> 0:13:11.640
<v Speaker 2>gravity of the galaxy is holding it together. It really

0:13:11.679 --> 0:13:14.360
<v Speaker 2>is pretty impressive on a cosmic scale. So if you

0:13:14.400 --> 0:13:17.200
<v Speaker 2>build enough mass, you can get very powerful gravity. But

0:13:17.200 --> 0:13:19.199
<v Speaker 2>if you take one more step, that's when you get

0:13:19.200 --> 0:13:21.280
<v Speaker 2>to the crazy town. You take a lot of mask

0:13:21.320 --> 0:13:24.560
<v Speaker 2>and you also squeeze it down to a really small

0:13:24.679 --> 0:13:27.400
<v Speaker 2>space so you can get really close to the mass.

0:13:27.800 --> 0:13:29.840
<v Speaker 2>That's when gravity really gets bunkers.

0:13:30.360 --> 0:13:35.400
<v Speaker 1>So you have like say, the Sun could fit in

0:13:35.480 --> 0:13:40.199
<v Speaker 1>a handbag, but it still retains the gravity of the

0:13:40.360 --> 0:13:43.600
<v Speaker 1>entire Sun. And then you fit a bunch of those

0:13:43.640 --> 0:13:47.080
<v Speaker 1>little handbag sized suns into a small area, then you

0:13:47.120 --> 0:13:49.920
<v Speaker 1>have just an enormous amount of gravity.

0:13:50.160 --> 0:13:53.600
<v Speaker 2>That's right. You could turn the Sun into a black hole. First,

0:13:53.600 --> 0:13:55.720
<v Speaker 2>imagine you're standing on the surface of the Sun.

0:13:55.920 --> 0:13:57.640
<v Speaker 1>Oh hot, too hot.

0:13:58.760 --> 0:14:00.800
<v Speaker 2>I assume you're wearing appropriate foot whear, you know, not

0:14:00.920 --> 0:14:02.280
<v Speaker 2>like ballerina.

0:14:01.720 --> 0:14:04.080
<v Speaker 1>Shoes flop flops for the Sun.

0:14:04.280 --> 0:14:05.960
<v Speaker 2>Now, the gravity on the surface of the Sun is

0:14:06.040 --> 0:14:08.760
<v Speaker 2>already going to be very powerful. Because the Sun is very,

0:14:08.840 --> 0:14:10.760
<v Speaker 2>very massive, but it's not a black hole, right, it's

0:14:10.800 --> 0:14:13.360
<v Speaker 2>emitting light. Now, take the Sun and shrane get down

0:14:13.400 --> 0:14:16.080
<v Speaker 2>to an object like a few kilometers across. If you're

0:14:16.120 --> 0:14:18.400
<v Speaker 2>still at the same distance from the center, you're at

0:14:18.400 --> 0:14:20.640
<v Speaker 2>where the surface of the Sun used to be, then

0:14:20.640 --> 0:14:23.480
<v Speaker 2>you're gonna feel the same thing. Nothing has changed for you.

0:14:23.480 --> 0:14:25.800
<v Speaker 2>You're still going to feel the gravity of the Sun

0:14:25.920 --> 0:14:28.000
<v Speaker 2>in the same way because all you've done is change

0:14:28.040 --> 0:14:31.080
<v Speaker 2>the internal configuration of the stuff inside the Sun. So

0:14:31.120 --> 0:14:33.160
<v Speaker 2>nothing will change for you in terms of the gravity

0:14:33.200 --> 0:14:35.480
<v Speaker 2>you feel if you're still at the same distance. But

0:14:35.520 --> 0:14:37.480
<v Speaker 2>shrinking the Sun down to a region like the size

0:14:37.520 --> 0:14:41.080
<v Speaker 2>of Los Angeles means you can actually get much closer

0:14:41.120 --> 0:14:43.640
<v Speaker 2>to it. Right, instead of having to stand of the surface,

0:14:43.960 --> 0:14:46.240
<v Speaker 2>you can now just be a few kilometers from the

0:14:46.280 --> 0:14:49.120
<v Speaker 2>center of the Sun with all of that mass concentrated there.

0:14:49.520 --> 0:14:52.360
<v Speaker 2>So that's why the gravity gets much much stronger. It's

0:14:52.360 --> 0:14:54.280
<v Speaker 2>not just about having a lot of mass. It's about

0:14:54.320 --> 0:14:56.560
<v Speaker 2>having a lot of mass in a very small space.

0:14:56.960 --> 0:14:58.760
<v Speaker 2>And if you did that, if you shrunk the Sun

0:14:58.840 --> 0:15:01.440
<v Speaker 2>down to the size of Us Angels, it would form

0:15:01.480 --> 0:15:02.320
<v Speaker 2>a black hole.

0:15:02.760 --> 0:15:07.720
<v Speaker 1>And that black hole is called traffic in Los Angeles. Okay,

0:15:07.840 --> 0:15:12.880
<v Speaker 1>So it's really about how tightly packed this matter is

0:15:12.920 --> 0:15:16.840
<v Speaker 1>such that it has a really strong effect of gravity

0:15:17.000 --> 0:15:20.840
<v Speaker 1>and a small amount of area, and so that is

0:15:20.960 --> 0:15:24.560
<v Speaker 1>what gives a black hole such powerful sort of I

0:15:24.600 --> 0:15:29.040
<v Speaker 1>guess drainage, universal drainage, Yeah, exactly.

0:15:29.400 --> 0:15:32.800
<v Speaker 2>In Newtonian gravity, the force between two objects depends on

0:15:32.840 --> 0:15:36.240
<v Speaker 2>the distance between them, like one over the distance squared.

0:15:36.560 --> 0:15:39.880
<v Speaker 2>So as the distance gets smaller, the force gets more powerful.

0:15:39.960 --> 0:15:43.000
<v Speaker 2>And because it's one over distance squared, the force gets

0:15:43.160 --> 0:15:46.160
<v Speaker 2>much much more powerful. If you're twice as close, it's

0:15:46.200 --> 0:15:49.240
<v Speaker 2>four times as powerful. If you're a thousand times as close,

0:15:49.320 --> 0:15:52.080
<v Speaker 2>it's a million times more powerful. So this force gets

0:15:52.120 --> 0:15:55.840
<v Speaker 2>extraordinarily powerful if you can shrink the distances between the objects.

0:15:56.120 --> 0:15:58.520
<v Speaker 2>That's what compacting the sun does for you. But then

0:15:58.560 --> 0:16:01.200
<v Speaker 2>you go over this incredible threat. It's not just like

0:16:01.240 --> 0:16:03.680
<v Speaker 2>the force gets stronger and stronger and stronger. It does

0:16:03.720 --> 0:16:06.960
<v Speaker 2>something sort of incredible, which is to create this event horizon,

0:16:07.120 --> 0:16:10.360
<v Speaker 2>a region of space where anything that enters can never.

0:16:10.320 --> 0:16:13.640
<v Speaker 1>Escape, even with a really really strong rope.

0:16:13.840 --> 0:16:16.400
<v Speaker 2>Even with a really really strong rope, even light that

0:16:16.560 --> 0:16:18.360
<v Speaker 2>enters the event horizon is trapped.

0:16:18.400 --> 0:16:20.640
<v Speaker 1>What does that mean for light to be trapped?

0:16:20.800 --> 0:16:24.080
<v Speaker 2>This is where Newtonian gravity no longer works to describe

0:16:24.080 --> 0:16:26.720
<v Speaker 2>what's going on. You're imagining light moves at the speed

0:16:26.720 --> 0:16:29.280
<v Speaker 2>of light, why can't it escape the black hole? And also,

0:16:29.600 --> 0:16:32.760
<v Speaker 2>light has no mass. In the Newtonian picture, gravity is

0:16:32.800 --> 0:16:36.080
<v Speaker 2>just a force between two objects that have mass. Photons

0:16:36.160 --> 0:16:38.480
<v Speaker 2>have no mass. How can the black hole pull on

0:16:38.600 --> 0:16:42.080
<v Speaker 2>them at all? So the Newtonian picture really totally breaks

0:16:42.120 --> 0:16:44.520
<v Speaker 2>down there. Instead, the way you need to think about

0:16:44.560 --> 0:16:47.400
<v Speaker 2>it is in Einstein's view of the universe, where gravity

0:16:47.520 --> 0:16:51.000
<v Speaker 2>is not a force, it's a curving of space time.

0:16:51.200 --> 0:16:54.880
<v Speaker 2>Space itself is not always just like an evenly spaced grid.

0:16:55.040 --> 0:16:57.720
<v Speaker 2>It has wiggles and curves in it. And if you

0:16:57.760 --> 0:17:01.080
<v Speaker 2>shoot like two laser beams through space, if it's totally flat,

0:17:01.120 --> 0:17:04.359
<v Speaker 2>then those laser beams will fly forever parallel, never touching.

0:17:04.760 --> 0:17:07.280
<v Speaker 2>But if space is curved, those laser beams will bend,

0:17:07.359 --> 0:17:10.000
<v Speaker 2>sometimes they may even cross, or they can diverge away

0:17:10.080 --> 0:17:13.199
<v Speaker 2>from each other based on the curvature of space. And

0:17:13.280 --> 0:17:16.520
<v Speaker 2>that curvature is not something we can see directly right.

0:17:16.520 --> 0:17:18.239
<v Speaker 2>We can't look at a piece of space and say, oh,

0:17:18.280 --> 0:17:20.760
<v Speaker 2>I see the curvature. Instead, we just see the effect

0:17:21.200 --> 0:17:24.679
<v Speaker 2>of that curvature on the motion of stuff. And so

0:17:24.760 --> 0:17:28.399
<v Speaker 2>Einstein tells us that when you have stuff in space, mass, energy,

0:17:28.760 --> 0:17:32.119
<v Speaker 2>anything like that, it changes the shape of space. So

0:17:32.200 --> 0:17:34.720
<v Speaker 2>back to the question of the photons. What's happening when

0:17:34.720 --> 0:17:36.680
<v Speaker 2>you have a huge amount of matter in a really

0:17:36.760 --> 0:17:39.920
<v Speaker 2>tiny space is that you've curved space so much that

0:17:39.960 --> 0:17:43.800
<v Speaker 2>photons moving through that cannot escape. Photons are affected by

0:17:43.840 --> 0:17:47.040
<v Speaker 2>mass because mass changes the shape of space and photons

0:17:47.280 --> 0:17:48.840
<v Speaker 2>move through that space.

0:17:49.280 --> 0:17:53.679
<v Speaker 1>So the gravity of the black hole causes space to

0:17:53.800 --> 0:17:57.880
<v Speaker 1>sort of warp into this funnel shape through which photons

0:17:58.280 --> 0:18:00.919
<v Speaker 1>have no choice but to travel, you know, through this

0:18:01.040 --> 0:18:02.280
<v Speaker 1>funnel right exactly.

0:18:02.359 --> 0:18:06.159
<v Speaker 2>Effectively, the shape of space is changed, is so distorted

0:18:06.200 --> 0:18:10.359
<v Speaker 2>inside the black hole that every direction forward is towards

0:18:10.400 --> 0:18:13.480
<v Speaker 2>the center of the black hole. When we talk about

0:18:13.520 --> 0:18:16.240
<v Speaker 2>space being curved, we really mean like it's changing the

0:18:16.400 --> 0:18:19.040
<v Speaker 2>organization of space, the way points are connected and the

0:18:19.080 --> 0:18:22.320
<v Speaker 2>distances between them, and so inside the black hole is

0:18:22.359 --> 0:18:25.320
<v Speaker 2>really just one direction of space, which is towards the.

0:18:25.240 --> 0:18:27.840
<v Speaker 1>Center that's unnerving.

0:18:29.640 --> 0:18:32.040
<v Speaker 2>And so this region we call this the event horizon.

0:18:32.080 --> 0:18:34.800
<v Speaker 2>It's the region around the black hole where nothing can

0:18:34.960 --> 0:18:37.800
<v Speaker 2>escape anything that enters that will never escape the event horizon,

0:18:37.880 --> 0:18:40.920
<v Speaker 2>even at time equals infinity at the end of the universe.

0:18:41.160 --> 0:18:43.439
<v Speaker 2>It's actually what we mean by the event horizon. The

0:18:43.440 --> 0:18:47.640
<v Speaker 2>technical definition is that region of space which after infinite time,

0:18:47.800 --> 0:18:50.560
<v Speaker 2>particles that enter will never leave. And the size of

0:18:50.560 --> 0:18:54.200
<v Speaker 2>that event horizon depends on the parameters of the black hole,

0:18:54.680 --> 0:18:57.720
<v Speaker 2>Like the bigger the mass inside the black hole, the

0:18:57.720 --> 0:19:00.880
<v Speaker 2>more space is curved, and the larger the event horizon.

0:19:01.080 --> 0:19:03.520
<v Speaker 2>It's actually a very simple calculation. It's called the short

0:19:03.560 --> 0:19:06.640
<v Speaker 2>siled radius that tells you the radius of the black hole,

0:19:06.680 --> 0:19:09.639
<v Speaker 2>which just depends on the mass, the gravitational constant G,

0:19:10.200 --> 0:19:11.200
<v Speaker 2>and the speed of light.

0:19:11.720 --> 0:19:15.120
<v Speaker 1>All Right, so we've got this sort of space funnel

0:19:15.200 --> 0:19:20.800
<v Speaker 1>that happens that you cannot escape because you're inside of

0:19:21.119 --> 0:19:24.280
<v Speaker 1>warped space that only goes in one direction, and that

0:19:24.400 --> 0:19:27.160
<v Speaker 1>is into I guess, the tummy of the black hole.

0:19:28.040 --> 0:19:33.320
<v Speaker 1>So say you could go inside the space funnel without

0:19:33.680 --> 0:19:37.240
<v Speaker 1>dying horribly and sort of turning into spaghetti, what would

0:19:37.280 --> 0:19:42.359
<v Speaker 1>you find there? Just like a really dense clump of matter, Like,

0:19:42.359 --> 0:19:43.240
<v Speaker 1>what is in there?

0:19:43.480 --> 0:19:45.720
<v Speaker 2>Boy? Do I wish I knew the answer that question?

0:19:45.840 --> 0:19:47.879
<v Speaker 2>Because I would be headed to Sockholm to pick up

0:19:47.880 --> 0:19:51.200
<v Speaker 2>my Nobel Prize. It's really one of the deepest questions

0:19:51.200 --> 0:19:54.280
<v Speaker 2>in physics because we don't know what would be there.

0:19:54.320 --> 0:19:57.080
<v Speaker 2>We have a prediction from general relativity, the theory that

0:19:57.119 --> 0:19:59.680
<v Speaker 2>tells us how space bends and how matter moves through

0:19:59.720 --> 0:20:01.879
<v Speaker 2>that in space, and that theory tells us that at

0:20:01.880 --> 0:20:04.879
<v Speaker 2>the heart of a black hole is a singularity because

0:20:04.880 --> 0:20:06.960
<v Speaker 2>things that fall in a black hole have to proceed

0:20:07.000 --> 0:20:10.719
<v Speaker 2>towards the center. Eventually everything does, and the power at

0:20:10.760 --> 0:20:13.840
<v Speaker 2>the center is so incredible that it's like a runaway effect.

0:20:13.840 --> 0:20:17.080
<v Speaker 2>It just keeps compacting, compacting, and compacting, so that everything

0:20:17.119 --> 0:20:19.479
<v Speaker 2>that falls into a black hole ends up at this

0:20:19.600 --> 0:20:24.280
<v Speaker 2>one point, a point of infinite density, infinite curvature of space.

0:20:24.800 --> 0:20:28.080
<v Speaker 2>That's the prediction from general relativity. But most physicists don't

0:20:28.160 --> 0:20:30.920
<v Speaker 2>view that as a real prediction. They view that as

0:20:30.920 --> 0:20:34.120
<v Speaker 2>an indication that the theory is failing. Anytime you get

0:20:34.280 --> 0:20:37.399
<v Speaker 2>nonsense predictions from your theory, you're like, well, maybe the

0:20:37.400 --> 0:20:39.800
<v Speaker 2>theory is not being applied correctly. I look at my kids,

0:20:39.840 --> 0:20:42.119
<v Speaker 2>for example, and I say, oh, in the last fifteen years,

0:20:42.119 --> 0:20:45.440
<v Speaker 2>they've grown from basically zero to two meters high. Does

0:20:45.440 --> 0:20:47.199
<v Speaker 2>that mean in the next fifteen years they're going to

0:20:47.200 --> 0:20:49.320
<v Speaker 2>grow to four meters high and then six meters high.

0:20:49.520 --> 0:20:51.960
<v Speaker 1>Only time will tell I.

0:20:51.920 --> 0:20:54.280
<v Speaker 2>Would say that's a nonsense prediction. It tells me that

0:20:54.320 --> 0:20:57.359
<v Speaker 2>I've extrapolated beyond the region where the theory makes any sense.

0:20:57.480 --> 0:21:00.000
<v Speaker 2>You know, a simple linear extrapolation doesn't make sense there.

0:21:00.040 --> 0:21:03.080
<v Speaker 2>I need a new idea for how humans live after

0:21:03.200 --> 0:21:06.320
<v Speaker 2>age fifteen. And that's what's happening in general relativity. We

0:21:06.359 --> 0:21:09.320
<v Speaker 2>don't think there really is a point of infinite density.

0:21:09.720 --> 0:21:12.040
<v Speaker 2>We think something else is going on, and we need

0:21:12.080 --> 0:21:14.960
<v Speaker 2>a new theory to describe it, because that infinite density

0:21:15.000 --> 0:21:18.639
<v Speaker 2>also violates fundamental principles of quantum mechanics tells us we

0:21:18.680 --> 0:21:21.760
<v Speaker 2>have an incredible amount of energy concentrated in a single

0:21:21.800 --> 0:21:25.359
<v Speaker 2>point without any sort of quantum fuzz, and so quantum

0:21:25.359 --> 0:21:27.760
<v Speaker 2>mechanics tells us you need some sort of quantum fuzz

0:21:27.800 --> 0:21:29.959
<v Speaker 2>when you have that much energy. So otherwise you know

0:21:30.040 --> 0:21:33.680
<v Speaker 2>something's location and it's momentum very very precisely, and that's

0:21:33.760 --> 0:21:37.119
<v Speaker 2>just not allowed by the Heisenberg uncertainty principle. So what's

0:21:37.200 --> 0:21:41.159
<v Speaker 2>inside a black hole would tell us how space actually works.

0:21:41.320 --> 0:21:43.879
<v Speaker 2>What is gravity in the quantum sense, Is it a

0:21:43.960 --> 0:21:46.960
<v Speaker 2>quantum theory, is actually a force or is there some

0:21:47.000 --> 0:21:50.320
<v Speaker 2>sort of space foam that bubbles up from fundamental quantum mechanics.

0:21:50.400 --> 0:21:52.879
<v Speaker 2>We just don't know. But if we could look inside

0:21:52.920 --> 0:21:56.040
<v Speaker 2>a black hole, we would get an enormous clue about

0:21:56.040 --> 0:21:58.920
<v Speaker 2>how space actually works, what gravity really is, and how

0:21:58.920 --> 0:22:01.760
<v Speaker 2>to unify general relativity and quantum mechanics.

0:22:01.800 --> 0:22:04.919
<v Speaker 1>That's really interesting because like I hear about these things, like,

0:22:05.000 --> 0:22:07.439
<v Speaker 1>you know, inside a black hole, you have sort of

0:22:07.440 --> 0:22:12.879
<v Speaker 1>this infinite amount of I guess suckage. But I guess

0:22:13.080 --> 0:22:15.280
<v Speaker 1>in a way that you're right, Like, it doesn't really

0:22:15.320 --> 0:22:20.159
<v Speaker 1>make sense for there to be a single, infinitely dense point,

0:22:20.560 --> 0:22:22.919
<v Speaker 1>especially with what you were describing with sort of the

0:22:23.000 --> 0:22:28.040
<v Speaker 1>quantum fuzz the uncertainty we know exists in quantum mechanics.

0:22:28.200 --> 0:22:30.560
<v Speaker 1>But I guess, like, are there any other theories? Are

0:22:30.600 --> 0:22:33.320
<v Speaker 1>there any other leads that we have as to what

0:22:33.440 --> 0:22:35.359
<v Speaker 1>is going on there? Like, how do we even go

0:22:35.440 --> 0:22:38.480
<v Speaker 1>about figuring out what could be happening?

0:22:38.800 --> 0:22:41.520
<v Speaker 2>Yeah, great question. It's really hard because we can see

0:22:41.560 --> 0:22:44.520
<v Speaker 2>inside a black hole. We do have various other theories.

0:22:44.520 --> 0:22:46.240
<v Speaker 2>We talked about a few of them on the podcast

0:22:46.640 --> 0:22:50.600
<v Speaker 2>ideas that black holes are actually slowly collapsing stars, or

0:22:50.640 --> 0:22:54.160
<v Speaker 2>maybe they're fuzzballs made out of strings, or maybe there's

0:22:54.160 --> 0:22:57.080
<v Speaker 2>something else entirely. We do have a bunch of theories,

0:22:57.080 --> 0:22:59.520
<v Speaker 2>but testing them is difficult because all the predictions they

0:22:59.520 --> 0:23:03.240
<v Speaker 2>make a hidden behind this cosmic veil, which makes it

0:23:03.280 --> 0:23:05.639
<v Speaker 2>pretty hard to know which one is right. But there

0:23:05.680 --> 0:23:07.919
<v Speaker 2>are other features to a black hole which present a

0:23:07.960 --> 0:23:12.480
<v Speaker 2>really fascinating opportunity because, as we talked about earlier, gravity

0:23:12.560 --> 0:23:15.320
<v Speaker 2>is not just based on the amount of mass something has.

0:23:15.520 --> 0:23:17.680
<v Speaker 2>It's also based on its spin and its energy in

0:23:17.760 --> 0:23:21.639
<v Speaker 2>terms of electromagnetism. So these other features of a black hole,

0:23:21.760 --> 0:23:25.880
<v Speaker 2>the spin and the charge, might present opportunities for cracking

0:23:25.920 --> 0:23:28.400
<v Speaker 2>them open and seeing what's inside.

0:23:28.720 --> 0:23:32.560
<v Speaker 1>Okay, well, I am really excited to find out what

0:23:32.720 --> 0:23:36.120
<v Speaker 1>is inside these ballerina black holes. But first let's take

0:23:36.119 --> 0:23:51.600
<v Speaker 1>a quick break. All right, and we are back and

0:23:51.720 --> 0:23:56.360
<v Speaker 1>we were talking about the universe's deadliest ballerina, a spinning

0:23:56.400 --> 0:23:59.560
<v Speaker 1>black hole, and what might be inside of their So

0:24:00.080 --> 0:24:01.919
<v Speaker 1>we have just gotten to the part where we are

0:24:01.960 --> 0:24:06.679
<v Speaker 1>talking about how black holes spin. So I'm having a

0:24:06.720 --> 0:24:10.880
<v Speaker 1>hard time picturing what it means for a black hole

0:24:10.920 --> 0:24:13.879
<v Speaker 1>to spin, Daniel, can you let me know, is this

0:24:14.080 --> 0:24:16.960
<v Speaker 1>like a black hole doing a pure What is the

0:24:17.000 --> 0:24:18.280
<v Speaker 1>spin of the black hole?

0:24:19.760 --> 0:24:23.119
<v Speaker 2>Yeah, it's a good question, but what is spinning exactly?

0:24:23.280 --> 0:24:25.560
<v Speaker 2>But we know that black holes are made of stuff, right,

0:24:25.560 --> 0:24:28.320
<v Speaker 2>there's stuff that has fallen in, there's mass, there's energy

0:24:28.359 --> 0:24:31.560
<v Speaker 2>in there. And when stuff falls into a black hole,

0:24:31.720 --> 0:24:34.360
<v Speaker 2>it has angular momentum. Like if you drop a ping

0:24:34.400 --> 0:24:37.320
<v Speaker 2>pong ball straight in towards the center of a black hole,

0:24:37.480 --> 0:24:39.280
<v Speaker 2>then you're not making it spin at all. But if

0:24:39.280 --> 0:24:40.960
<v Speaker 2>you drop a ping pong ball and it hits the

0:24:40.960 --> 0:24:44.040
<v Speaker 2>black hole sort of far from the center, then you're

0:24:44.080 --> 0:24:46.359
<v Speaker 2>like giving it a push. The way somebody on the

0:24:46.359 --> 0:24:48.600
<v Speaker 2>Merry Go Round is spinning around and you give them

0:24:48.600 --> 0:24:50.640
<v Speaker 2>a tug near the edge of the Merry Go Round.

0:24:50.680 --> 0:24:53.720
<v Speaker 2>You're applying a torque to the Merry Go Round. Same

0:24:53.760 --> 0:24:55.560
<v Speaker 2>way you shoot a bunch of ping pong balls at

0:24:55.600 --> 0:24:57.800
<v Speaker 2>a black hole, but you do it off center. You're

0:24:57.840 --> 0:25:00.600
<v Speaker 2>going to add some spin to the black hole. So

0:25:00.640 --> 0:25:03.040
<v Speaker 2>as long as things fall into a black hole and

0:25:03.119 --> 0:25:06.280
<v Speaker 2>don't head directly for the center, if they spin around first,

0:25:06.359 --> 0:25:08.399
<v Speaker 2>then as they fall in, they're going to keep that spin.

0:25:08.680 --> 0:25:12.000
<v Speaker 2>Because in our universe, angular momentum is conserved can't just

0:25:12.200 --> 0:25:15.320
<v Speaker 2>go away, which means because the black hole is made

0:25:15.359 --> 0:25:18.000
<v Speaker 2>of stuff that was spinning around it, eventually a black

0:25:18.000 --> 0:25:22.119
<v Speaker 2>hole itself is spinning. What's actually spinning? I mean, if

0:25:22.119 --> 0:25:24.440
<v Speaker 2>you imagine like a singularity at the heart of the

0:25:24.480 --> 0:25:28.679
<v Speaker 2>black hole, it's just a point. Points themselves cannot spin.

0:25:29.240 --> 0:25:31.720
<v Speaker 2>So people imagine that what's going on inside a black

0:25:31.760 --> 0:25:35.359
<v Speaker 2>hole is not a point spinning but a ring. Instead

0:25:35.400 --> 0:25:37.359
<v Speaker 2>of having a point of infinite space, you have like

0:25:37.400 --> 0:25:41.600
<v Speaker 2>a ring of singularities, and that ring is spinning. Again,

0:25:41.880 --> 0:25:44.199
<v Speaker 2>this is the general relativity prediction, which we think is

0:25:44.280 --> 0:25:47.640
<v Speaker 2>probably wrong, but that's the more complex picture of what's

0:25:47.680 --> 0:25:49.840
<v Speaker 2>happening inside a spinning black hole.

0:25:49.960 --> 0:25:53.919
<v Speaker 1>So you have multiple singularities that form sort of a

0:25:54.040 --> 0:25:56.600
<v Speaker 1>ring inside potentially mm hmmm.

0:25:56.920 --> 0:25:59.840
<v Speaker 2>Because a ring can spin, it has some spatial extent,

0:26:00.359 --> 0:26:03.119
<v Speaker 2>it has some spatial extent at least in one dimension,

0:26:03.400 --> 0:26:06.719
<v Speaker 2>and that ring itself can spin to preserve the angular momentum.

0:26:06.760 --> 0:26:10.480
<v Speaker 2>Because again, angular menum can't just go away in our universe,

0:26:10.800 --> 0:26:11.960
<v Speaker 2>we think it's conserved.

0:26:12.359 --> 0:26:15.400
<v Speaker 1>Okay, so how do we even know that black holes

0:26:15.560 --> 0:26:16.080
<v Speaker 1>can spin?

0:26:16.280 --> 0:26:19.320
<v Speaker 2>Yeah? Great question. According to the theory, they can spin

0:26:19.359 --> 0:26:21.600
<v Speaker 2>in general relativity, and also, as we talked about later

0:26:21.640 --> 0:26:23.920
<v Speaker 2>in the podcast, we've seen a bunch of black holes

0:26:23.960 --> 0:26:27.040
<v Speaker 2>and we've seen the effect of their spinning on the

0:26:27.119 --> 0:26:29.879
<v Speaker 2>stuff around them. And this is a really fascinating feature

0:26:29.920 --> 0:26:33.160
<v Speaker 2>of general relativity, that the spin of an object does

0:26:33.359 --> 0:26:36.600
<v Speaker 2>change its gravity. I mean, again, in the Newtonian picture,

0:26:36.600 --> 0:26:39.400
<v Speaker 2>which I think is pretty intuitive for most people, gravity

0:26:39.440 --> 0:26:42.040
<v Speaker 2>is just a force between two objects that half mass,

0:26:42.400 --> 0:26:44.760
<v Speaker 2>like the Earth is pulling on you. If you're a

0:26:44.800 --> 0:26:47.760
<v Speaker 2>satellite in space orbiting the Earth, you think that your

0:26:47.840 --> 0:26:50.160
<v Speaker 2>orbit is affected only by the mass of the Earth.

0:26:50.480 --> 0:26:54.120
<v Speaker 2>Why would it change the gravity if the Earth is spinning, right,

0:26:54.240 --> 0:26:58.560
<v Speaker 2>the formula is just like gmm over r square. There's

0:26:58.560 --> 0:27:01.040
<v Speaker 2>no opening in there to describe this spinning of the object.

0:27:01.359 --> 0:27:03.600
<v Speaker 2>And Newton would say it doesn't matter if the Earth spins,

0:27:03.640 --> 0:27:06.640
<v Speaker 2>it's like, got the same mass configuration everywhere. As long

0:27:06.640 --> 0:27:09.359
<v Speaker 2>as it's a perfect sphere, it should have the same gravity.

0:27:09.840 --> 0:27:12.880
<v Speaker 2>But in Einstein's picture of the universe, that spin does

0:27:13.080 --> 0:27:15.080
<v Speaker 2>change the gravity of the object.

0:27:15.160 --> 0:27:17.960
<v Speaker 1>And so we're on the Earth and so we are

0:27:18.080 --> 0:27:21.800
<v Speaker 1>experiencing a different gravity from the Earth because it is spinning.

0:27:22.000 --> 0:27:26.080
<v Speaker 1>Then if it was staying still, and so things around

0:27:26.119 --> 0:27:29.920
<v Speaker 1>a black hole would also be experiencing a different effect

0:27:29.920 --> 0:27:34.480
<v Speaker 1>from a spinning black hole versus a stationary black hole exactly.

0:27:34.760 --> 0:27:38.400
<v Speaker 2>And the crucial thing to understand is that in general relativity,

0:27:38.400 --> 0:27:42.320
<v Speaker 2>it's not just that mass bend space, but the things

0:27:42.320 --> 0:27:45.560
<v Speaker 2>that bend space come together in a complicated dance. It's

0:27:45.560 --> 0:27:47.800
<v Speaker 2>described not just by like a number, as it is

0:27:47.840 --> 0:27:50.840
<v Speaker 2>for Newton, like a single number the mass, but this

0:27:51.040 --> 0:27:54.359
<v Speaker 2>stress energy tensor tensor is just a fancy way of saying,

0:27:54.400 --> 0:27:57.080
<v Speaker 2>like a matrix, a bunch of stuff all organized. So

0:27:57.119 --> 0:28:00.639
<v Speaker 2>the mass definitely affects things, energy affects things, can energy

0:28:00.640 --> 0:28:05.399
<v Speaker 2>affects things. Also, Electromagnetic energy and spin all come together

0:28:05.440 --> 0:28:08.000
<v Speaker 2>in this complicated dance. But it's not just like you

0:28:08.080 --> 0:28:09.920
<v Speaker 2>add up all the energy and you get a number

0:28:09.960 --> 0:28:12.440
<v Speaker 2>and that's how much the curvature of space is. It

0:28:12.480 --> 0:28:15.240
<v Speaker 2>is more complicated, and spin affects the curvature of space

0:28:15.280 --> 0:28:18.360
<v Speaker 2>in a really weird way in that it spins space.

0:28:19.000 --> 0:28:21.199
<v Speaker 2>They call it frame dragging because it really is like

0:28:21.320 --> 0:28:23.919
<v Speaker 2>spinning space like a fluid. So what happens to an

0:28:23.960 --> 0:28:26.679
<v Speaker 2>object around something that's spinning is that you're not just

0:28:26.840 --> 0:28:30.679
<v Speaker 2>pulled towards it by its gravity. You're also spun. So

0:28:30.760 --> 0:28:33.280
<v Speaker 2>if you have a satellite orbiting the Earth or a

0:28:33.320 --> 0:28:36.040
<v Speaker 2>black hole and that Earth or black hole is spinning,

0:28:36.240 --> 0:28:38.560
<v Speaker 2>it's going to apply a little torque, a little twist

0:28:38.920 --> 0:28:42.200
<v Speaker 2>to the thing orbiting. We've actually measured this. We have

0:28:42.240 --> 0:28:45.719
<v Speaker 2>a satellite orbiting the Earth called gravity Probe B. It

0:28:45.720 --> 0:28:48.880
<v Speaker 2>has very very precise gyroscopes to measure its direction and

0:28:48.920 --> 0:28:51.560
<v Speaker 2>its spin. We have a whole podcast episode about this,

0:28:51.920 --> 0:28:54.440
<v Speaker 2>and they've detected this effect that the spinning of the

0:28:54.480 --> 0:28:57.040
<v Speaker 2>Earth applies like a little torque to this satellite. It's

0:28:57.160 --> 0:28:58.920
<v Speaker 2>very very subtle. In the case of the Earth, it

0:28:59.120 --> 0:29:02.760
<v Speaker 2>requires extra ordinary precision even to detect it, but it's there.

0:29:02.800 --> 0:29:03.600
<v Speaker 2>We've confirmed it.

0:29:04.080 --> 0:29:07.000
<v Speaker 1>So if you drop like a marble down a funnel,

0:29:07.040 --> 0:29:11.160
<v Speaker 1>like straight in the center down a stationary funnel, it

0:29:11.280 --> 0:29:13.280
<v Speaker 1>just goes straight down. If you drop it sort of

0:29:13.520 --> 0:29:16.960
<v Speaker 1>on the side of a stationary funnel, it rolls down

0:29:16.960 --> 0:29:18.880
<v Speaker 1>the side and then into the center. But if the

0:29:18.920 --> 0:29:23.000
<v Speaker 1>funnel like is spinning, like if you start like sort

0:29:23.000 --> 0:29:26.200
<v Speaker 1>of moving the funnel around and then put the marble

0:29:26.360 --> 0:29:28.840
<v Speaker 1>on the side of the funnel, the marble itself will

0:29:28.880 --> 0:29:31.960
<v Speaker 1>start to like sort of circle around as it goes

0:29:32.040 --> 0:29:34.800
<v Speaker 1>down into the center of the funnel. Is that kind

0:29:34.800 --> 0:29:35.960
<v Speaker 1>of what's happening.

0:29:36.040 --> 0:29:37.760
<v Speaker 2>That's sort of what's happening. There's some tricky bits there

0:29:37.760 --> 0:29:40.880
<v Speaker 2>about the funnel pushing on the marble, but in effect, yeah,

0:29:40.920 --> 0:29:43.200
<v Speaker 2>the spinning of the black hole or the spinning of

0:29:43.240 --> 0:29:46.400
<v Speaker 2>the object applies a spin to stuff near it. So

0:29:46.440 --> 0:29:48.600
<v Speaker 2>in the case of a spinning black hole, you don't

0:29:48.640 --> 0:29:51.320
<v Speaker 2>just have the event horizon, you also have this region

0:29:51.520 --> 0:29:55.080
<v Speaker 2>past the event horizon, called the ergosphere, where the black

0:29:55.120 --> 0:29:57.959
<v Speaker 2>hole is applying a certain amount of twist to stuff.

0:29:58.400 --> 0:30:00.920
<v Speaker 2>We talk once about how you can ext diract energy

0:30:01.000 --> 0:30:04.000
<v Speaker 2>from a black hole basically by dropping rocks near it.

0:30:04.080 --> 0:30:06.640
<v Speaker 2>Those rocks get spun as they go through the ergosphere,

0:30:06.760 --> 0:30:09.800
<v Speaker 2>extracting some energy from the black hole basically for free.

0:30:09.840 --> 0:30:12.280
<v Speaker 2>So I think Freeman Dyson or maybe Roger Penrose came

0:30:12.360 --> 0:30:14.280
<v Speaker 2>up with this plant to use black holes as a

0:30:14.320 --> 0:30:15.840
<v Speaker 2>power source, which.

0:30:15.640 --> 0:30:18.400
<v Speaker 1>Is pretty awesome, sounds really easy. All we need to

0:30:18.440 --> 0:30:20.720
<v Speaker 1>do is get really close to a black hole.

0:30:22.080 --> 0:30:24.760
<v Speaker 2>Exactly. So these spinning black holes have this weird effect

0:30:24.840 --> 0:30:28.680
<v Speaker 2>on space time, and it also affects their event horizon,

0:30:28.960 --> 0:30:31.040
<v Speaker 2>like how close you can get to a black hole

0:30:31.080 --> 0:30:34.240
<v Speaker 2>and still escape depends not just on the mass of

0:30:34.280 --> 0:30:37.560
<v Speaker 2>the black hole, but also on its spin and its

0:30:37.560 --> 0:30:41.160
<v Speaker 2>electric charge. Because these things enter into the stress energy

0:30:41.200 --> 0:30:44.880
<v Speaker 2>tensor that general relativity uses to do this calculation. It

0:30:44.920 --> 0:30:47.440
<v Speaker 2>can change the size of the event horizon if you

0:30:47.520 --> 0:30:50.480
<v Speaker 2>spin your black hole or if you give it electric charge.

0:30:50.600 --> 0:30:54.320
<v Speaker 1>So are we kind of getting into the limitations of

0:30:54.480 --> 0:30:57.840
<v Speaker 1>how fast a black hole can spin, because if it

0:30:57.880 --> 0:31:01.920
<v Speaker 1>is affecting the event horizon, and presumably there has to

0:31:01.960 --> 0:31:05.800
<v Speaker 1>be some characteristics to the event horizon to keep that

0:31:05.920 --> 0:31:10.040
<v Speaker 1>black hole stable. Otherwise, like if you change that event

0:31:10.120 --> 0:31:12.960
<v Speaker 1>horizon too much, what could happen to the black hole?

0:31:13.200 --> 0:31:16.240
<v Speaker 2>Exactly right, And the crucial thing to understand is that

0:31:16.400 --> 0:31:20.040
<v Speaker 2>spinning a black hole will shrink its event horizon. This

0:31:20.120 --> 0:31:22.880
<v Speaker 2>is counterintuitive because you feel like, well, you're adding energy

0:31:22.880 --> 0:31:25.600
<v Speaker 2>to the black hole. Isn't that just putting more fuel

0:31:25.640 --> 0:31:28.280
<v Speaker 2>on the fire. Remember that spin and things like electric

0:31:28.400 --> 0:31:30.880
<v Speaker 2>charge have a complicated way that they contribute to the

0:31:30.880 --> 0:31:33.920
<v Speaker 2>curvature of space. It's not really very intuitive, but adding

0:31:34.040 --> 0:31:37.160
<v Speaker 2>spin or electric charge to your black hole will shrink

0:31:37.280 --> 0:31:40.520
<v Speaker 2>the event horizon, will make it smaller. It's possible to

0:31:40.560 --> 0:31:42.880
<v Speaker 2>get closer to one of these objects if it's spinning

0:31:43.280 --> 0:31:47.040
<v Speaker 2>or has electric charge than otherwise. And as you were saying,

0:31:47.120 --> 0:31:50.320
<v Speaker 2>there's a breakdown point. If you spin the black hole enough,

0:31:50.480 --> 0:31:54.320
<v Speaker 2>the event horizon shrinks down to zero, which means there

0:31:54.400 --> 0:31:57.680
<v Speaker 2>is no event horizon, which means you've like cracked open

0:31:57.800 --> 0:32:02.040
<v Speaker 2>the black hole and revealed the brand mystery that's inside

0:32:02.040 --> 0:32:02.360
<v Speaker 2>of it.

0:32:02.480 --> 0:32:05.440
<v Speaker 1>I bet it's nugat. I bet it's filled with nugat.

0:32:06.680 --> 0:32:08.480
<v Speaker 2>I really think you should have a snack before we

0:32:08.520 --> 0:32:10.680
<v Speaker 2>do these episodes, Katie.

0:32:11.200 --> 0:32:15.400
<v Speaker 1>I'm sorry if you make space sound so delicious, Well

0:32:15.440 --> 0:32:18.680
<v Speaker 1>that's I mean. But presumably we don't know if this

0:32:18.720 --> 0:32:21.280
<v Speaker 1>has ever happened or if it could ever happen.

0:32:21.840 --> 0:32:24.040
<v Speaker 2>We don't know if this has ever happened or if

0:32:24.080 --> 0:32:26.480
<v Speaker 2>it actually could ever happen. Again, it's sort of a

0:32:26.520 --> 0:32:29.320
<v Speaker 2>prediction of general relativity, And we don't think that general

0:32:29.360 --> 0:32:32.560
<v Speaker 2>relativity is the law of the actual universe. It's just

0:32:32.600 --> 0:32:34.960
<v Speaker 2>the law of the universe we describe in our head,

0:32:34.960 --> 0:32:38.960
<v Speaker 2>which so far works perfectly to describe everything we see.

0:32:39.040 --> 0:32:41.440
<v Speaker 2>We think that it probably fails the inside of a

0:32:41.520 --> 0:32:44.640
<v Speaker 2>black hole, but we've never seen that, So this is

0:32:44.680 --> 0:32:48.640
<v Speaker 2>a prediction of general relativity that if you overspin a

0:32:48.800 --> 0:32:52.760
<v Speaker 2>black hole, you will reveal a naked singularity, you will

0:32:52.760 --> 0:32:56.160
<v Speaker 2>crack it open, you'll shrink the event horizon down to zero,

0:32:56.640 --> 0:32:59.440
<v Speaker 2>which is really fascinating because it seems like, on one hand,

0:32:59.480 --> 0:33:01.960
<v Speaker 2>an opportunity to learn this secret of the universe, like,

0:33:02.160 --> 0:33:04.240
<v Speaker 2>let's go out and overspin a black hole. I want

0:33:04.240 --> 0:33:06.840
<v Speaker 2>to see what's inside of it. Right. On the other hand,

0:33:06.880 --> 0:33:10.120
<v Speaker 2>it's like, well, is that really allowed? Is there something

0:33:10.120 --> 0:33:12.480
<v Speaker 2>in the universe that would prevent that from happening?

0:33:13.080 --> 0:33:17.120
<v Speaker 1>So do we have any calculations as to like how

0:33:17.400 --> 0:33:20.760
<v Speaker 1>fast a black hole can spin before it breaks itself apart?

0:33:20.880 --> 0:33:23.480
<v Speaker 2>Yeah, we do actually have the calculation from general relativity,

0:33:23.800 --> 0:33:26.200
<v Speaker 2>and it tells us that if there's more energy in

0:33:26.240 --> 0:33:29.120
<v Speaker 2>the spin than there is in the mass, then the

0:33:29.200 --> 0:33:31.880
<v Speaker 2>radius of the event horizon becomes a negative, which basically

0:33:31.920 --> 0:33:34.520
<v Speaker 2>means there is no event horizon. So that means the

0:33:34.560 --> 0:33:37.800
<v Speaker 2>bigger the black hole, the faster it can spin. So

0:33:37.840 --> 0:33:40.320
<v Speaker 2>it's not like there's a maximum spin rang for all

0:33:40.360 --> 0:33:43.480
<v Speaker 2>black holes, but there's like a ratio if you have

0:33:43.560 --> 0:33:45.800
<v Speaker 2>more energy in your spin than you do in your

0:33:45.880 --> 0:33:48.920
<v Speaker 2>mass than the event horizon shrinks. It's actually the same

0:33:48.960 --> 0:33:51.880
<v Speaker 2>thing for electric charge. We did a podcast episode about

0:33:51.920 --> 0:33:55.680
<v Speaker 2>that recently. If you overcharge the black hole, meaning adding

0:33:55.760 --> 0:33:59.719
<v Speaker 2>more energy to it in electromagnetism by adding like electrons

0:33:59.760 --> 0:34:03.240
<v Speaker 2>for and there's a certain ratio of mass to charge

0:34:03.280 --> 0:34:06.240
<v Speaker 2>you cannot exceed because it will shrink the event horizon

0:34:06.600 --> 0:34:09.560
<v Speaker 2>down to zero. So now there's the interesting question of like, well,

0:34:09.719 --> 0:34:11.480
<v Speaker 2>what happens if you do it? Or is there a

0:34:11.520 --> 0:34:13.840
<v Speaker 2>physical way to actually make this happen?

0:34:14.120 --> 0:34:16.360
<v Speaker 1>I mean, I think it sounds like you got to

0:34:16.360 --> 0:34:19.319
<v Speaker 1>put a sign up at the teacups ride that you

0:34:19.400 --> 0:34:21.680
<v Speaker 1>must be this big of a black hole to be

0:34:21.719 --> 0:34:22.960
<v Speaker 1>able to spin this bath.

0:34:25.120 --> 0:34:31.320
<v Speaker 2>Let's just regulate the problem away. Huh. How very progressive

0:34:31.320 --> 0:34:34.040
<v Speaker 2>of you, Katie. But there's sort of two interesting questions

0:34:34.040 --> 0:34:36.640
<v Speaker 2>here to tease apart. One is like does the universe

0:34:36.640 --> 0:34:39.359
<v Speaker 2>say this is actually impossible? And the other is could

0:34:39.520 --> 0:34:43.120
<v Speaker 2>you make it happen? Right? Some things are not against

0:34:43.160 --> 0:34:45.640
<v Speaker 2>the rules, but you have no way of making them happen,

0:34:45.680 --> 0:34:48.120
<v Speaker 2>no way of like going from our universe to creating

0:34:48.120 --> 0:34:51.200
<v Speaker 2>some configuration that you're curious about, Like, not everything is

0:34:51.280 --> 0:34:54.719
<v Speaker 2>possible to build. You have to assemble things, right. You

0:34:54.760 --> 0:34:56.879
<v Speaker 2>need a recipe for saying I'm gonna build this house,

0:34:56.880 --> 0:34:58.600
<v Speaker 2>I'm gonna put one brick and then the next brick,

0:34:58.600 --> 0:35:01.080
<v Speaker 2>and then the next brick, a way to step by

0:35:01.120 --> 0:35:03.960
<v Speaker 2>step put it together. And so while we don't think

0:35:04.000 --> 0:35:07.040
<v Speaker 2>that it's against the rules of general relativity to crack

0:35:07.120 --> 0:35:09.480
<v Speaker 2>open a black hole this way by overspinning it, we

0:35:09.520 --> 0:35:11.680
<v Speaker 2>don't think that's actually a recipe that would let you

0:35:11.760 --> 0:35:13.840
<v Speaker 2>do it. There's no way to, like, step by step

0:35:13.960 --> 0:35:14.480
<v Speaker 2>make this.

0:35:14.400 --> 0:35:16.800
<v Speaker 1>Happen, because if you got close enough to a black

0:35:16.840 --> 0:35:20.200
<v Speaker 1>hole to build something, it seems like the black hole

0:35:20.280 --> 0:35:22.280
<v Speaker 1>would just suck all your tools away.

0:35:22.480 --> 0:35:24.960
<v Speaker 2>That's one example of a practical reason why you might

0:35:25.000 --> 0:35:26.680
<v Speaker 2>not be able to do this. But people have thought

0:35:26.719 --> 0:35:29.080
<v Speaker 2>about other thought experiments, like say you have a black

0:35:29.160 --> 0:35:31.520
<v Speaker 2>hole and you want to try overspinning it. Take the

0:35:31.560 --> 0:35:33.520
<v Speaker 2>suggestion you made earlier, which is like, well, let's just

0:35:33.520 --> 0:35:35.839
<v Speaker 2>shoot ping pong balls at it, but not right at

0:35:35.880 --> 0:35:37.879
<v Speaker 2>the center. Right. Every time you shoot a ping pong

0:35:37.960 --> 0:35:40.080
<v Speaker 2>ball at a spinning black hole, you're giving it a

0:35:40.080 --> 0:35:42.640
<v Speaker 2>little push. So can't you just keep doing that forever,

0:35:42.800 --> 0:35:46.799
<v Speaker 2>eventually exceeding this ratio and cracking open the black hole. Well,

0:35:46.840 --> 0:35:49.560
<v Speaker 2>it turns out that's not actually possible. What happens when

0:35:49.560 --> 0:35:51.680
<v Speaker 2>you shoot something into a spinning black hole is that

0:35:51.719 --> 0:35:54.480
<v Speaker 2>the black hole causes it to accelerate, which gives off

0:35:54.640 --> 0:35:59.480
<v Speaker 2>some gravitational radiation, because every acceleration requires some kind of

0:35:59.560 --> 0:36:02.640
<v Speaker 2>radiation to conserve momentum. You can't just like zoom in

0:36:02.680 --> 0:36:06.000
<v Speaker 2>one direction without pushing off in the other direction. And

0:36:06.040 --> 0:36:09.880
<v Speaker 2>this gravitational radiation, it turns out, will decrease the angular

0:36:09.960 --> 0:36:12.920
<v Speaker 2>momentum of the thing you're throwing in. So basically, a

0:36:12.960 --> 0:36:16.000
<v Speaker 2>black hole that's right on the edge of being extremal

0:36:16.239 --> 0:36:20.560
<v Speaker 2>that's almost overspun will basically despin stuff that you throw

0:36:20.640 --> 0:36:23.800
<v Speaker 2>into it, so that it's impossible to overspin the black hole.

0:36:24.239 --> 0:36:25.959
<v Speaker 1>So it's self limiting in a way.

0:36:26.120 --> 0:36:28.759
<v Speaker 2>Yeah, exactly, it's sort of self limiting. This is called

0:36:28.800 --> 0:36:31.920
<v Speaker 2>the back reaction. Like the black hole and the object

0:36:32.040 --> 0:36:35.160
<v Speaker 2>have effects on each other before they fall in, and

0:36:35.239 --> 0:36:37.319
<v Speaker 2>so they're pulling on each other, tugging on each other,

0:36:37.520 --> 0:36:41.080
<v Speaker 2>radiating away some gravitational energy. And it's very complicated calculation,

0:36:41.120 --> 0:36:43.080
<v Speaker 2>but people have gone through this and try to imagine

0:36:43.120 --> 0:36:46.200
<v Speaker 2>all possible ways you can throw things into a black hole,

0:36:46.480 --> 0:36:49.400
<v Speaker 2>and none of them can actually push it over the edge.

0:36:49.680 --> 0:36:53.400
<v Speaker 2>That's not saying this configuration is impossible. It's not saying

0:36:53.520 --> 0:36:56.200
<v Speaker 2>overspun black holes are not possible in the universe. It's

0:36:56.200 --> 0:36:59.319
<v Speaker 2>saying we don't know of a recipe for building one,

0:36:59.400 --> 0:37:02.560
<v Speaker 2>because as soon you get close to overspun black holes

0:37:02.560 --> 0:37:06.200
<v Speaker 2>become very very good at rejecting any more angular momentum.

0:37:06.400 --> 0:37:09.560
<v Speaker 1>I mean, it's hard to feel like this black hole

0:37:09.680 --> 0:37:14.240
<v Speaker 1>is not intentionally creating rules so that it doesn't rip apart.

0:37:14.560 --> 0:37:18.200
<v Speaker 1>But I guess that's a very homo sapient mindset that

0:37:18.239 --> 0:37:20.120
<v Speaker 1>there's some intentionality here.

0:37:20.400 --> 0:37:23.239
<v Speaker 2>No, I think you're totally onto something really fascinating, which

0:37:23.280 --> 0:37:26.040
<v Speaker 2>is like the secrets of the universe are hidden behind

0:37:26.080 --> 0:37:28.839
<v Speaker 2>this event horizon. Then as soon as we're clever enough

0:37:28.840 --> 0:37:30.960
<v Speaker 2>to think about, ooh wait, here's a loophole, maybe we

0:37:30.960 --> 0:37:33.360
<v Speaker 2>can break it open, it turns out there's like another

0:37:33.440 --> 0:37:35.880
<v Speaker 2>reason why that can't work. It does feel almost like

0:37:35.920 --> 0:37:39.040
<v Speaker 2>a conspiracy theory, like we have all the answers in

0:37:39.040 --> 0:37:41.840
<v Speaker 2>this little box, but there's no way to open the box.

0:37:42.280 --> 0:37:45.200
<v Speaker 1>We'd find the off switch to the universe in there,

0:37:45.480 --> 0:37:47.200
<v Speaker 1>and they don't want us to find it.

0:37:48.480 --> 0:37:50.479
<v Speaker 2>This is very similar to a topic we talked about

0:37:50.480 --> 0:37:53.759
<v Speaker 2>recently about overcharging the black hole. In a similar way,

0:37:53.760 --> 0:37:56.600
<v Speaker 2>if a black hole has a lot of electric charge,

0:37:56.760 --> 0:37:58.880
<v Speaker 2>then it repels stuff you try to throw in it

0:37:58.920 --> 0:38:01.400
<v Speaker 2>that has more electric charge charge, so it prevents you

0:38:01.480 --> 0:38:04.560
<v Speaker 2>from overcharging the black hole. This is the way black

0:38:04.560 --> 0:38:07.839
<v Speaker 2>holes prevent you from over spinning themselves with this back

0:38:07.920 --> 0:38:10.600
<v Speaker 2>reaction on stuff you throw in. And then people try

0:38:10.600 --> 0:38:13.000
<v Speaker 2>to be even more clever, like, well, what about internal

0:38:13.120 --> 0:38:16.120
<v Speaker 2>quantum spin? You know what if you like take something

0:38:16.160 --> 0:38:19.399
<v Speaker 2>that has internal quantum spin, like electrons, and you drop

0:38:19.480 --> 0:38:22.920
<v Speaker 2>them straight into the black hole without angular momentum, wouldn't

0:38:22.920 --> 0:38:25.080
<v Speaker 2>that add to the overall spin of the black hole?

0:38:25.239 --> 0:38:27.600
<v Speaker 2>Great idea. So people went off to do the calculations

0:38:27.719 --> 0:38:30.520
<v Speaker 2>and it turns out there are spin spin interactions like

0:38:30.520 --> 0:38:32.919
<v Speaker 2>the spinning of the black hole and the quantum spin

0:38:32.960 --> 0:38:36.520
<v Speaker 2>of this object will induce an interaction between the two things,

0:38:36.719 --> 0:38:40.440
<v Speaker 2>which again will lower the angular momentum of the falling

0:38:40.480 --> 0:38:44.560
<v Speaker 2>in object, avoiding going over the threshold. So the summary

0:38:44.640 --> 0:38:47.440
<v Speaker 2>is that we know of no way to overspin a

0:38:47.560 --> 0:38:51.160
<v Speaker 2>black hole. We currently think it might be impossible again

0:38:51.400 --> 0:38:54.640
<v Speaker 2>not impossible for it to exist as an overspun object.

0:38:54.760 --> 0:38:57.120
<v Speaker 2>To break this limit, we just don't know how to

0:38:57.120 --> 0:38:57.800
<v Speaker 2>make it happen.

0:38:58.120 --> 0:39:01.239
<v Speaker 1>Man, that really does seem like the black hole is

0:39:01.480 --> 0:39:06.120
<v Speaker 1>just trying to frustrate particle physicists like you.

0:39:07.560 --> 0:39:09.080
<v Speaker 2>It doesn't take a lot. You're just going to have

0:39:09.120 --> 0:39:11.440
<v Speaker 2>the secrets of the universe and hide them from us.

0:39:13.000 --> 0:39:17.160
<v Speaker 1>So I'm also curious to find out because we've talked

0:39:17.200 --> 0:39:21.399
<v Speaker 1>about how black holes have a maximum speed limit that

0:39:21.640 --> 0:39:26.399
<v Speaker 1>the black hole Highway patrol manages to keep in check

0:39:26.560 --> 0:39:31.120
<v Speaker 1>through these radiation, these spin spin interactions. But I'm also

0:39:31.239 --> 0:39:34.040
<v Speaker 1>curious if there is a minimum speed limit for a

0:39:34.040 --> 0:39:36.160
<v Speaker 1>black hole, if a black hole could get away with

0:39:36.280 --> 0:39:39.680
<v Speaker 1>not spinning. But maybe first we should take a quick

0:39:39.719 --> 0:39:42.879
<v Speaker 1>break to make sure that we don't get ticketed by

0:39:42.960 --> 0:39:58.520
<v Speaker 1>the black hole police. So we are back and we

0:39:58.560 --> 0:40:03.319
<v Speaker 1>are keeping this podcast under the speed limit. But as

0:40:03.320 --> 0:40:05.879
<v Speaker 1>we know, with speed limits, it's possible to go too

0:40:06.040 --> 0:40:09.880
<v Speaker 1>slow on a highway, people get mad. So is this

0:40:10.000 --> 0:40:13.319
<v Speaker 1>the same thing with black holes? Do they hack to

0:40:13.400 --> 0:40:17.840
<v Speaker 1>spin or can they just laze around and stay still.

0:40:18.040 --> 0:40:20.200
<v Speaker 2>It's a great question because most of the description of

0:40:20.239 --> 0:40:22.920
<v Speaker 2>black holes you hear about out there are these very simple,

0:40:23.000 --> 0:40:27.040
<v Speaker 2>short style black holes, just stuff in space with massive

0:40:27.080 --> 0:40:30.200
<v Speaker 2>gravity and not even talking about the spin, and that's

0:40:30.200 --> 0:40:32.560
<v Speaker 2>the sort of like generic description of a black hole.

0:40:32.880 --> 0:40:34.600
<v Speaker 2>But if you go out there and look for stuff

0:40:34.640 --> 0:40:38.040
<v Speaker 2>in space, there's basically nothing that isn't spinning. Right, Everything

0:40:38.160 --> 0:40:42.360
<v Speaker 2>in space is spinning. There was inherent angular momentum too stuff,

0:40:42.640 --> 0:40:45.680
<v Speaker 2>and that can't go away, and so stuff keeps spinning.

0:40:46.080 --> 0:40:48.680
<v Speaker 2>So it really makes no sense to imagine a huge,

0:40:48.840 --> 0:40:51.520
<v Speaker 2>massive object with all of this stuff thrown into it,

0:40:51.800 --> 0:40:56.600
<v Speaker 2>somehow perfectly balanced between positive and negative angle momentum so

0:40:56.640 --> 0:41:00.080
<v Speaker 2>that it doesn't spin. It's like flipping a billion coins

0:41:00.120 --> 0:41:03.799
<v Speaker 2>and getting exactly one half of them heads and exactly

0:41:03.840 --> 0:41:06.480
<v Speaker 2>one half of them tails. That's what you would need.

0:41:06.520 --> 0:41:09.200
<v Speaker 2>So it's not impossible for a black hole to have

0:41:09.239 --> 0:41:14.239
<v Speaker 2>no spin. It's just extraordinarily improbable. It's like an enormous

0:41:14.280 --> 0:41:16.480
<v Speaker 2>pencil balanced on its very tip forever.

0:41:16.800 --> 0:41:19.440
<v Speaker 1>I guess that's a little bit scary. The idea of

0:41:19.480 --> 0:41:24.640
<v Speaker 1>a black hole that's perfectly imbalanced, somehow defying probability and

0:41:24.760 --> 0:41:27.160
<v Speaker 1>just still kind of sucking things in it.

0:41:27.080 --> 0:41:29.720
<v Speaker 2>Is pretty weird. And black holes are weird and powerful objects.

0:41:29.760 --> 0:41:31.640
<v Speaker 2>And all the ones that we've seen out there in

0:41:31.719 --> 0:41:34.520
<v Speaker 2>space are spinning. We can tell they're spinning because the

0:41:34.600 --> 0:41:37.880
<v Speaker 2>stuff around them is spinning. Like the black hole picture

0:41:37.920 --> 0:41:40.160
<v Speaker 2>that we've seen, what we're actually looking at when we

0:41:40.200 --> 0:41:42.760
<v Speaker 2>look at that picture is not the black hole itself.

0:41:42.880 --> 0:41:44.759
<v Speaker 2>There's like a blank spot in the middle where the

0:41:44.800 --> 0:41:47.319
<v Speaker 2>black holes like not giving off any light. What we're

0:41:47.320 --> 0:41:50.160
<v Speaker 2>looking at is like the Crispy Kream donut of stuff

0:41:50.239 --> 0:41:53.440
<v Speaker 2>around the black hole that's falling in, and that stuff

0:41:53.520 --> 0:41:56.480
<v Speaker 2>is glowing. It's so hot because of the tidal forces,

0:41:56.520 --> 0:41:59.840
<v Speaker 2>the frictional gravity of the black hole, rubbing and squeezing

0:41:59.840 --> 0:42:02.920
<v Speaker 2>all that stuff as it orbits, the swishing around the

0:42:02.920 --> 0:42:05.760
<v Speaker 2>black hole before it actually gets flushed down this cosmic

0:42:05.800 --> 0:42:08.399
<v Speaker 2>toilet bowl. And every black hole that we've ever seen

0:42:08.719 --> 0:42:11.880
<v Speaker 2>has this very strong spin to the stuff around it,

0:42:11.920 --> 0:42:13.680
<v Speaker 2>which means that it is also spinning.

0:42:13.880 --> 0:42:17.200
<v Speaker 1>I mean, you did scold me about needing a snack

0:42:17.280 --> 0:42:20.160
<v Speaker 1>before the show, and then you describe the stuff around

0:42:20.239 --> 0:42:24.359
<v Speaker 1>a black hole as Krispy Kreme donut getting mixed messages here,

0:42:24.400 --> 0:42:26.439
<v Speaker 1>and then you described it as like a toilet bowl,

0:42:26.480 --> 0:42:30.640
<v Speaker 1>so getting really mixed messages here. So we have measured

0:42:31.000 --> 0:42:33.399
<v Speaker 1>things around a black hole. How do we do that?

0:42:33.600 --> 0:42:36.080
<v Speaker 2>Yeah, that's a great question. One thing we can do

0:42:36.239 --> 0:42:39.120
<v Speaker 2>is look at the orbits of stars around the black

0:42:39.120 --> 0:42:43.440
<v Speaker 2>hole like in other galaxies. We can't resolve individual stars,

0:42:43.480 --> 0:42:46.680
<v Speaker 2>but we can tell how fast stars are spinning. We

0:42:46.680 --> 0:42:49.360
<v Speaker 2>can look at like the velocity of streams of stars.

0:42:49.360 --> 0:42:52.160
<v Speaker 2>We can't make out the individual ones, especially near the

0:42:52.200 --> 0:42:54.879
<v Speaker 2>centers of those other galaxies, but we can tell how

0:42:54.920 --> 0:42:56.799
<v Speaker 2>fast they're moving because of the red shift, and we

0:42:56.800 --> 0:42:59.120
<v Speaker 2>can tell the density, and so we can infer the

0:42:59.160 --> 0:43:02.879
<v Speaker 2>presence of these super massive black holes in other galaxies.

0:43:03.200 --> 0:43:06.080
<v Speaker 2>And sometimes we can directly see the effect of spin

0:43:06.360 --> 0:43:09.200
<v Speaker 2>on the stuff around it, Like if the black hole

0:43:09.280 --> 0:43:12.359
<v Speaker 2>is spinning, it changes like how close stuff can get

0:43:12.440 --> 0:43:14.640
<v Speaker 2>to the black hole, and it also changes how that

0:43:14.680 --> 0:43:17.680
<v Speaker 2>stuff is spun. There was one case where we saw

0:43:17.800 --> 0:43:21.280
<v Speaker 2>two black holes orbiting each other. So like a really

0:43:21.320 --> 0:43:25.080
<v Speaker 2>big black hole called OJ two nine seven. It has

0:43:25.120 --> 0:43:29.440
<v Speaker 2>like almost nineteen billion solar masses, one of the biggest

0:43:29.440 --> 0:43:32.520
<v Speaker 2>black holes out there that we know about. It's orbited

0:43:32.560 --> 0:43:35.080
<v Speaker 2>by another black hole that has just like one hundred

0:43:35.080 --> 0:43:39.200
<v Speaker 2>and fifty million solar masses. I mean, already a gigantic object,

0:43:39.200 --> 0:43:42.000
<v Speaker 2>but tiny in comparison to the big Mama black hole

0:43:42.000 --> 0:43:44.800
<v Speaker 2>it's orbiting, and the orbit of this smaller black hole

0:43:44.960 --> 0:43:48.160
<v Speaker 2>is processing. Imagine like an elliptical orbit, not a perfect circle,

0:43:48.400 --> 0:43:50.800
<v Speaker 2>but the smaller black hole is moving around in an ellipse,

0:43:50.920 --> 0:43:53.800
<v Speaker 2>and ellips is like an elongated circle. Well, the direction

0:43:53.920 --> 0:43:56.600
<v Speaker 2>of the elongation is changing as the little black hole

0:43:56.719 --> 0:43:59.200
<v Speaker 2>orbits the big black hole. This is like the spin

0:43:59.360 --> 0:44:01.960
<v Speaker 2>of the orbit of the little black hole around the

0:44:02.000 --> 0:44:05.720
<v Speaker 2>big black hole, and the procession of that orbit tells

0:44:05.800 --> 0:44:08.520
<v Speaker 2>us something about the spin of the big black hole

0:44:08.920 --> 0:44:11.840
<v Speaker 2>because its spin is contributing to that procession.

0:44:12.040 --> 0:44:15.120
<v Speaker 1>That's crazy. I mean first of all that a big

0:44:15.160 --> 0:44:18.600
<v Speaker 1>black hole can suck up a littler black hole, but

0:44:18.719 --> 0:44:22.920
<v Speaker 1>also just that you can see that change in movement

0:44:23.280 --> 0:44:26.440
<v Speaker 1>that would only be possible given sort of the spin

0:44:27.200 --> 0:44:30.439
<v Speaker 1>of the bigger black hole. Can we actually measure how

0:44:30.520 --> 0:44:34.560
<v Speaker 1>fast the big Mama black hole is spinning given the

0:44:34.760 --> 0:44:36.640
<v Speaker 1>procession of the smaller black hole.

0:44:36.880 --> 0:44:39.200
<v Speaker 2>Yeah, we can, Actually, we can make a calculation, and

0:44:39.239 --> 0:44:42.440
<v Speaker 2>the surface of that black hole is moving at almost

0:44:42.480 --> 0:44:47.880
<v Speaker 2>sixty thousand kilometers per second, which is like twenty percent

0:44:48.120 --> 0:44:51.440
<v Speaker 2>of the speed of light. Sort of amazing. Now, this

0:44:51.520 --> 0:44:54.520
<v Speaker 2>thing is so big though, it's radius is so huge.

0:44:54.640 --> 0:44:57.840
<v Speaker 2>It's like three hundred and sixty au it's the distance

0:44:57.880 --> 0:45:00.319
<v Speaker 2>between the Earth and the Sun. It's so large. Even

0:45:00.320 --> 0:45:02.120
<v Speaker 2>though it's moving to twenty percent of the speed of light,

0:45:02.160 --> 0:45:06.400
<v Speaker 2>it still takes five million seconds to complete one spin.

0:45:06.600 --> 0:45:09.400
<v Speaker 2>So it's such a big bear that it still takes

0:45:09.400 --> 0:45:11.520
<v Speaker 2>a huge amount of time to spin once.

0:45:12.040 --> 0:45:16.800
<v Speaker 1>Five million seconds is how many years?

0:45:17.120 --> 0:45:20.120
<v Speaker 2>Five million seconds is like sixteen percent of a year.

0:45:20.400 --> 0:45:24.640
<v Speaker 1>Okay. I can't think in seconds, so that's like two months.

0:45:24.719 --> 0:45:26.520
<v Speaker 2>So this thing is spinning at twenty percent of the

0:45:26.520 --> 0:45:29.840
<v Speaker 2>speed of light, still takes two months to complete one spin.

0:45:30.239 --> 0:45:34.200
<v Speaker 1>Okay. Because my perception of seconds are different. Like when

0:45:34.200 --> 0:45:37.000
<v Speaker 1>I'm in this podcast, they go by very fast because

0:45:37.040 --> 0:45:41.359
<v Speaker 1>I'm really interested. If I'm waiting for a bus to come,

0:45:41.480 --> 0:45:43.320
<v Speaker 1>the seconds are very long.

0:45:43.520 --> 0:45:46.960
<v Speaker 2>But there's another black hole that's spinning even faster. This

0:45:47.000 --> 0:45:50.120
<v Speaker 2>one is really small. It has only two million solar masses.

0:45:50.400 --> 0:45:54.439
<v Speaker 2>It's NNGC thirteen sixty five. But the cool thing about

0:45:54.440 --> 0:45:56.560
<v Speaker 2>this black hole is it doesn't have like a baby

0:45:56.600 --> 0:45:58.520
<v Speaker 2>black hole orbiting it, but it's close enough that we

0:45:58.520 --> 0:46:00.880
<v Speaker 2>can study the accretion disc in great detail.

0:46:01.120 --> 0:46:04.200
<v Speaker 1>Is the accretion disc the stuff that is caught up

0:46:04.480 --> 0:46:05.680
<v Speaker 1>circling the black hole.

0:46:06.200 --> 0:46:08.400
<v Speaker 2>It's the stuff that's on deck about to go into

0:46:08.400 --> 0:46:10.600
<v Speaker 2>the black hole. It's like falling in, but because it

0:46:10.600 --> 0:46:13.560
<v Speaker 2>has angular momentum, it just doesn't fall straight in the

0:46:13.600 --> 0:46:15.600
<v Speaker 2>same way like the Earth doesn't just fall into the

0:46:15.640 --> 0:46:18.560
<v Speaker 2>Sun because of the Sun's gravity it's in orbit. This

0:46:18.600 --> 0:46:21.279
<v Speaker 2>stuff also has angular momentum, which slows it down, which

0:46:21.280 --> 0:46:24.080
<v Speaker 2>prevents it from falling immediately in. It has to like

0:46:24.200 --> 0:46:26.759
<v Speaker 2>radiate away some of its energy in order to fall in.

0:46:27.120 --> 0:46:29.840
<v Speaker 2>So inside the accretion disk, this stuff is like bumping

0:46:29.880 --> 0:46:32.800
<v Speaker 2>and grinding and glowing, giving off some of its energy

0:46:33.200 --> 0:46:35.839
<v Speaker 2>just before it falls into the black hole. And so

0:46:35.880 --> 0:46:39.320
<v Speaker 2>by studying what's happening inside that accretion disc, it's like

0:46:39.360 --> 0:46:41.839
<v Speaker 2>a probe for what the gravity of the black hole

0:46:41.920 --> 0:46:44.000
<v Speaker 2>is doing to it. We can understand the tidle force

0:46:44.080 --> 0:46:46.760
<v Speaker 2>is the strength of the gravity and also the effect

0:46:46.880 --> 0:46:49.440
<v Speaker 2>of the spin, because the spin of the black hole

0:46:49.600 --> 0:46:52.960
<v Speaker 2>changes like how close the accretion disc can get to

0:46:53.040 --> 0:46:53.920
<v Speaker 2>the event horizon.

0:46:54.320 --> 0:46:58.359
<v Speaker 1>So, if it's spinning faster, can the accretion disk get

0:46:58.440 --> 0:47:00.040
<v Speaker 1>closer to the event.

0:47:00.640 --> 0:47:03.360
<v Speaker 2>Yes, exactly. If it's spinning the same way as the

0:47:03.400 --> 0:47:05.839
<v Speaker 2>accretion disc, then the accretion disc can get very very

0:47:05.840 --> 0:47:08.680
<v Speaker 2>close to the black hole without actually falling in. Whereas

0:47:08.719 --> 0:47:10.839
<v Speaker 2>if the accretion disc is spinning one way the black

0:47:10.840 --> 0:47:13.160
<v Speaker 2>hole is spinning the other way, then you end up

0:47:13.160 --> 0:47:15.799
<v Speaker 2>with this like weird gap between the black hole and

0:47:15.840 --> 0:47:18.279
<v Speaker 2>the accretion disc where stuff in that gap can't exist

0:47:18.320 --> 0:47:20.600
<v Speaker 2>because it would just fall immediately into the black hole.

0:47:20.680 --> 0:47:22.560
<v Speaker 2>But if they're spinning together, then the spin of the

0:47:22.560 --> 0:47:25.520
<v Speaker 2>black hole like accentuates the spin of the accretion disc

0:47:25.840 --> 0:47:27.960
<v Speaker 2>and it helps it spin faster. It can actually get

0:47:27.960 --> 0:47:30.759
<v Speaker 2>closer in before falling into the black hole. So by

0:47:30.760 --> 0:47:32.719
<v Speaker 2>looking at like the size of the gap between the

0:47:32.719 --> 0:47:35.359
<v Speaker 2>event horizon and the start of the accretion disk, they

0:47:35.400 --> 0:47:38.880
<v Speaker 2>can measure the rate of spin of the black hole itself.

0:47:38.920 --> 0:47:41.840
<v Speaker 2>And this guy is spinning at eighty five percent of

0:47:41.920 --> 0:47:45.400
<v Speaker 2>the maximum rate allowed for this mass black hole.

0:47:45.760 --> 0:47:49.839
<v Speaker 1>Man, he's got like the universe police kind of following him.

0:47:49.840 --> 0:47:52.160
<v Speaker 1>They haven't put their lights on yet, but they're keeping

0:47:52.160 --> 0:47:53.399
<v Speaker 1>an eye on them.

0:47:53.800 --> 0:47:56.360
<v Speaker 2>Exactly, And so this is fascinating, Like, Wow, this guy's

0:47:56.600 --> 0:48:00.480
<v Speaker 2>close to an overspun black hole. Be really interesting to

0:48:00.520 --> 0:48:02.680
<v Speaker 2>watch as that stuff falls in, to see like, is

0:48:02.719 --> 0:48:05.560
<v Speaker 2>it's beating up? Does it gradually approach ninety nine point

0:48:05.680 --> 0:48:08.560
<v Speaker 2>nine nine nine percent? Or are we wrong about how

0:48:08.560 --> 0:48:11.399
<v Speaker 2>black holes can't be overspun and maybe this one will

0:48:11.440 --> 0:48:14.560
<v Speaker 2>actually get cracked open, maybe that stuff will fall in

0:48:14.760 --> 0:48:16.520
<v Speaker 2>and erase the event horizon.

0:48:16.719 --> 0:48:20.080
<v Speaker 1>We better keep an eye on it also, because the

0:48:20.360 --> 0:48:23.239
<v Speaker 1>faster it spins, the closer you can get to the

0:48:23.280 --> 0:48:26.680
<v Speaker 1>event horizon without falling in, Daniel, is this the kind

0:48:26.680 --> 0:48:28.799
<v Speaker 1>of black hole that you would want to travel to

0:48:29.080 --> 0:48:32.040
<v Speaker 1>and try to sort of drop some sonar into the

0:48:32.040 --> 0:48:33.160
<v Speaker 1>middle of the black hole?

0:48:33.320 --> 0:48:35.520
<v Speaker 2>I mean, I don't even travel the conferences anymore. There's

0:48:35.600 --> 0:48:37.640
<v Speaker 2>no way that I'm going to visit a black hole.

0:48:37.760 --> 0:48:40.759
<v Speaker 2>Absolutely not. I am too old for that. But I'm

0:48:40.840 --> 0:48:44.799
<v Speaker 2>very happy to send up you know, co hosts, guest hosts,

0:48:44.880 --> 0:48:46.800
<v Speaker 2>all these kind of people who would happily volunteer.

0:48:47.000 --> 0:48:50.800
<v Speaker 1>It's an interesting pool of people. You'd be okay sending

0:48:50.880 --> 0:48:53.000
<v Speaker 1>to a black hole as long as you bring.

0:48:52.840 --> 0:48:54.560
<v Speaker 2>Your travel mike and tell us what you're learning as

0:48:54.560 --> 0:48:55.040
<v Speaker 2>you fall in.

0:48:55.280 --> 0:48:57.440
<v Speaker 1>Yeah. I do have a good wind screen on it,

0:48:57.520 --> 0:48:59.000
<v Speaker 1>so it should still come through clear.

0:48:59.120 --> 0:49:00.680
<v Speaker 2>But you know, I think the less to take away

0:49:00.680 --> 0:49:04.600
<v Speaker 2>from this is that space is so much weirder than

0:49:04.640 --> 0:49:07.560
<v Speaker 2>we thought it was. Even the idea of space being

0:49:07.640 --> 0:49:12.000
<v Speaker 2>bent into curves by mass is weirder than Newton thought of.

0:49:12.400 --> 0:49:14.839
<v Speaker 2>But there's so much more to it than just that

0:49:15.239 --> 0:49:18.320
<v Speaker 2>space is not just bent into curves. It's also spun.

0:49:18.560 --> 0:49:23.160
<v Speaker 2>It's flowing like a fluid around very massive objects, dragged

0:49:23.200 --> 0:49:26.880
<v Speaker 2>along with them like a fork twirling that spaghetti. And

0:49:26.920 --> 0:49:29.680
<v Speaker 2>that changes the way that black holes operate. The event

0:49:29.719 --> 0:49:32.240
<v Speaker 2>horizon of a black hole is not just a function

0:49:32.360 --> 0:49:34.920
<v Speaker 2>of its mass. It's also a function of its spin

0:49:35.360 --> 0:49:36.920
<v Speaker 2>and its electric charge.

0:49:37.120 --> 0:49:40.959
<v Speaker 1>I feel like this is a great personality test of

0:49:41.239 --> 0:49:44.680
<v Speaker 1>who wants to see the black hole over spin and

0:49:44.719 --> 0:49:48.400
<v Speaker 1>break apart and maybe break the universe? And who would

0:49:48.440 --> 0:49:51.640
<v Speaker 1>like the black hole to not break apart and keep

0:49:51.680 --> 0:49:52.320
<v Speaker 1>things safe?

0:49:52.440 --> 0:49:54.640
<v Speaker 2>Oh my god, who would be in that second category?

0:49:54.640 --> 0:49:56.640
<v Speaker 2>Who would not want the black hole to wreak the

0:49:56.680 --> 0:50:02.880
<v Speaker 2>rules the universe? Who we've been talking about here, not me?

0:50:04.400 --> 0:50:07.200
<v Speaker 2>Remember that seeing the universe break the rules, it's not

0:50:07.239 --> 0:50:10.840
<v Speaker 2>a failure, it's not a problem, it's an opportunity. Those

0:50:10.880 --> 0:50:12.880
<v Speaker 2>are the moments when we learn what the real rules

0:50:12.880 --> 0:50:14.799
<v Speaker 2>of the universe are. The universe is out there, we

0:50:14.840 --> 0:50:17.160
<v Speaker 2>think following some set of rules, and we have in

0:50:17.200 --> 0:50:20.560
<v Speaker 2>our heads some internal description of that, a model of

0:50:20.600 --> 0:50:23.440
<v Speaker 2>how we think the universe works, and when those two

0:50:23.520 --> 0:50:26.200
<v Speaker 2>things clash, that's when we get to update our list.

0:50:26.239 --> 0:50:28.520
<v Speaker 2>Were like, oh, turns out we were wrong about what's

0:50:28.520 --> 0:50:31.480
<v Speaker 2>going on over here. Let's fix things. But we need

0:50:31.520 --> 0:50:34.040
<v Speaker 2>those clues sometimes, we need the universe to show us

0:50:34.080 --> 0:50:37.000
<v Speaker 2>what's wrong with our understanding of how it works by

0:50:37.040 --> 0:50:40.920
<v Speaker 2>contradicting our predictions. And so if we see the universe

0:50:41.000 --> 0:50:43.480
<v Speaker 2>breaking the rules that we thought, it's not a failure.

0:50:43.560 --> 0:50:46.759
<v Speaker 2>It's a huge leap forward. It's an open door to

0:50:46.800 --> 0:50:49.840
<v Speaker 2>a deeper understanding of how the universe actually works.

0:50:50.080 --> 0:50:53.080
<v Speaker 1>Well, kids, you heard Daniel. You gotta break rules to

0:50:53.160 --> 0:50:55.000
<v Speaker 1>learn exactly.

0:50:55.080 --> 0:50:58.840
<v Speaker 2>Unfortunately, it seems like black holes are fortresses of knowledge.

0:50:59.040 --> 0:51:01.480
<v Speaker 2>Not only do they have these event horizons that keep

0:51:01.560 --> 0:51:05.560
<v Speaker 2>us from seeing what happens at extraordinarily extreme circumstances, but

0:51:05.640 --> 0:51:09.080
<v Speaker 2>also there very wildly at protecting those event horizons. You

0:51:09.120 --> 0:51:12.280
<v Speaker 2>thought you could overcharge a black hole, it repels your idea.

0:51:12.520 --> 0:51:15.040
<v Speaker 2>You thought you could overspin a black hole. It's got

0:51:15.080 --> 0:51:17.680
<v Speaker 2>its own spin doctors to keep you from doing it. So,

0:51:17.800 --> 0:51:19.879
<v Speaker 2>for now, at least, we don't know how to crack

0:51:19.960 --> 0:51:21.040
<v Speaker 2>open a black hole.

0:51:21.200 --> 0:51:23.360
<v Speaker 1>We need a rogue black hole, a maverick.

0:51:23.520 --> 0:51:25.520
<v Speaker 2>We need to put a black hole in witness protection.

0:51:27.960 --> 0:51:29.120
<v Speaker 1>What would that even look like?

0:51:29.560 --> 0:51:32.319
<v Speaker 2>Put a black hole inside another black hole? I don't know,

0:51:32.440 --> 0:51:35.600
<v Speaker 2>we'll ask the SBI. Well, thanks very much everybody for

0:51:35.640 --> 0:51:39.240
<v Speaker 2>going on this journey inside the mysteries of the universe,

0:51:39.320 --> 0:51:41.759
<v Speaker 2>wondering what's going on inside a black hole and how

0:51:41.800 --> 0:51:45.080
<v Speaker 2>we could ever know and whether we ever will. And

0:51:45.120 --> 0:51:48.000
<v Speaker 2>thanks very much Katie for taking this crazy physics tour

0:51:48.080 --> 0:51:49.520
<v Speaker 2>and breaking all the rules with us.

0:51:49.760 --> 0:51:52.360
<v Speaker 1>Thank you for not shooting me into the center of

0:51:52.400 --> 0:51:52.960
<v Speaker 1>a black.

0:51:52.719 --> 0:51:56.959
<v Speaker 2>Hole, not yet, at least stay tuned. Thanks everyone, tune

0:51:57.000 --> 0:52:07.360
<v Speaker 2>in next time. Thanks for listening, and remember that Daniel

0:52:07.400 --> 0:52:10.840
<v Speaker 2>and Jorge Explain the Universe is a production of iHeartRadio.

0:52:11.120 --> 0:52:16.239
<v Speaker 2>For more podcasts from iHeartRadio, visit the iHeartRadio app, Apple Podcasts,

0:52:16.400 --> 0:52:18.760
<v Speaker 2>or wherever you listen to your favorite shows.