Physicist Brian Cox Explains Black Holes in Plain English | Joe Rogan

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Brian Cox

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Professor Brian Cox is an English physicist and Professor of Particle Physics in the School of Physics and Astronomy at the University of Manchester in the UK.

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Black holes, wormholes & other things I'll never understand

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There's a supermassive black hole at the center of every galaxy. Yeah. But there's also other black holes that aren't necessarily in the center of galaxies. Yeah, so these little ones were little, you know. A few times the mass of the sun. And they're from collapsed stars. So they are stars at the end of their life. Very bigger than the sun, more massive than the sun. But they run out of their fuel and they start to collapse because gravity squashes them. And if they're sufficiently massive, then there's nothing that can stop the collapse. And so they collapse as far as we know to a point, right, essentially an infinitely dense point. We don't really know what happens at the, we don't know what happens right in the middle. But they collapse to such an extent that there's a region around it where, from which light can't escape. And that's a, so nothing can escape. And that's a black hole. And what happens to them? Do they travel? Are they moving through space? Yeah, they're still stars. You know, so they're still there. They're surrounded, this region where if you fall in, it's called the event horizon. And if you go across that horizon, then you are going to the center. There's one way of thinking about it, which is quite cool, which is that the time and space sort of flip is one way to think about it. So in the same way that we are going into the future now. So we're going to tomorrow. There's nothing we can do about it. We are going to tomorrow. And in the same way, if you fall in across the event horizon of a black hole, you are going to the middle, the singularity it's called. So that's, that's your future. Every, every line of your future points to the center of the black hole. So it's kind of the ultimate of no escape for the ultimate prison. You're going to get squashed to an infinitely dense point. Not every star becomes a black hole at the end of its life. No, because if something like the sun, we have a small star. It's quite small. Yeah. And when it collapses, there's a, there's a sort of a pressure, a force if you like, which is caused by the fact that electrons don't like to be very close to each other. So it's called the Pauli exclusion principle. But essentially what happens is that, so as they get squashed close from closer together, they move faster and faster to sort of get out of each other's way if you like. And that makes a force which holds them up. And so that creates what's called a white dwarf star. So, so you can have a blob of matter. They're about the size of the earth, but they're about the mass of the sun. And so that's, that's for smaller stars. They end up as these white dwarf things, which are very dense objects. There's another version, which is called a neutron star, which is the same thing, but for neutrons and they, they move faster and faster. So if it's massive enough that it overwhelms the electron thing, then the electrons sort of fall, crush into protons and turn into neutrons and the whole thing starts again. And so a neutron star can be, you know, elite one and a half times the mass of the sun, let's say, but it can be about what, 10 miles across. So, so that's an incredibly dense ball of matter held up by this, the neutrons moving around. It's got a fancy name. It's called neutron degeneracy pressure, but if you go even bigger than even that can't hold it up. And as far as we know, then there's no known force that we know of that can hold, hold the thing up if it's, if it's too massive. And so that's when it just almost winks out of existence. If you like, it collapses and collapses and collapses. And that's when you get a black hole. We try to put that in a perspective of the, the sun is a million times bigger than the earth. And this, this neutron star is what would you say one and a half times the mass of the sun, but 10 miles wide? Yeah. Yeah. So, and there's loads of those around that they're called pulsars. So we, we, we see those all over the place. The first one that was discovered was called LGM1, because they spin very fast. And then it was called LGM1 because it's a very regular pulse and they thought it was little green men. So they called it kind of jokingly little green men one. And then so yeah, we've seen that there's one called the crab pulsar, which is in the crab nebula, which we saw the supernova explosion. So that's when one of these stars explodes at the end of its life and then collapses to form a neutron star. And we saw that in 1054 AD. Well, wasn't there some speculation that our gal or our solar system at one point was, had a, was a binary star system and that one of those stars had become a dwarf? I don't know. Someone had read something about that in relationship to the dense object they believe is outside the Kuiper belt. Yeah. I mean, there's some evidence, a bit of evidence that there's something out there. Yeah. Because of the periodic extinctions and things on earth, like you get periodic bombardments from out in the Kuiper belt. So yeah, I think one of the theories is periodic extinctions. Well, yeah. So for me, like the, you know, there have been, there have been mass extinctions on earth when, when a lot of the life died. And we don't know what caused all those, but sometimes their impacts from space, that seems clear. And so yeah, there are theories that there's something orbiting out there which can disrupt all these objects out in the Kuiper belt that sends loads of comets and asteroids inwards to the inner solar system and can cause havoc. And so there's some people look at those theories.