Joe Rogan has his mind blown by Lawrence Krauss

Hello freak bitches. What about the ideas that the universe is in a constant state of contraction and expansion? No, it isn't. No, it isn't. No, it isn't. No, it's not been abandoned. Some physicists still argue that there's a cycle because it looks nice. And they are. But I think most people, I mean, there's some people who are arguing for that. Do you think they're just trying to tie up something neat? Well, I think they're trying to tie up their ignorance in something that isn't any more plausible in the picture that it expands forever. And as far as we can tell, the most likely possibility is that our universe will expand forever. But to make you a little bit happier, it's quite possible. The best pictures that we have of the early universe is that we actually, our universe isn't unique, isn't alone, that there are many universes. We call it a multiverse. And that at any instant in time, in kind of a cosmic super time, there's always a universe being born. So that multiverse might be infinite and eternal. Where are they? Outside of our universe. How's that even possible? Of course it's possible. I understand. I'm not questioning it. Okay, no, no. I just would like you to define it. Well, first of all, the simplest possibility is that they're outside the region we can see, right? For example, the edges of our visible universe, space is expanding faster away from us than light. Because we taught you in school, nothing can travel faster than light. You may remember that from school. We lied. Okay. Well, no, you have to parse it more carefully like a lawyer. Nothing can travel through space faster than light. But space can do whatever the hell it wants. So locally, as I told you, that radio host is at rest. They're not moving in the other end of the galaxy, at the other end of the visible universe. And we're at rest. But the space between us is expanding. So that galaxy, like a surfer, is being carried away from us faster than light. Relative to the water, the surfer isn't moving. Right? But relative to the shore, the surfer is. Right? Right. Okay. This galaxy is not moving relative to its local surroundings. But it's moving away from us faster than light. And like a surfer in an undertow, they can swim really fast in the water. But if the water's moving away from the shore, then let me back the shore. Right? And so that galaxy, the light from that galaxy is traveling through space at the speed of light. But if the space in between us and the galaxy is moving faster than light, then the poor light can never make it to us. We call that a horizon. Wow. So the space is traveling too far for the light to reach us. So are I too fast? Too fast. Too fast. Too fast. So the light can't catch up with the expansion of space, and it never gets to us. And that galaxy disappears from our causal horizon, we call it. We'll never be able to see it. We'll never be able to interact with it. We'll never be okay. And it could be that there are different regions so far away from us where space is expanding faster than light, which have a very different history than our own. So there could be space could be infinite. Just our simple space that we know of and love could be infinite in extent. And different regions of that space had different histories. And some of those regions, everything we can see, we know emerged from a single point. Okay? We can tell that. We can tell that by measuring the big bang expansion of everything we see and working backwards. And the universe, our visible universe was once smaller and smaller and smaller. If we go back in time, we can actually follow the laws of physics back to the earliest moments of the big bang until those laws break down. And we can make predictions about the universe. It looked like all those predictions agree exactly with the observations we make, which tell us that that picture works. But another region, if you wish, could have come from a different big bang. But is that another universe? Or is it a part of the universe that we can't see? Here's how we've changed. And this is semantics, but non-trivial semantics. Similarly, when I was a kid, universe meant everything. Everything, right. But we say that's a pretty stupid definition. A better definition is an operational one. Universe means that region of space with which at one time we could have communicated or one time in the future, even if the future is infinite, we might communicate with. Because that describes the region of space where cause and effect works. Some measurable distance. Yes. We think of a universe as that region throughout which everything could affect everything else, ultimately, in an infinitely long time. And in that picture, universes can be restricted in size. And then other regions which could never have affected us and which will never affect us in the future, we call other universes. And now there are many different versions of a multiverse, but that's the simplest version. This picture we call inflation, which I just did two little clips associated with the new book. One was for a publisher and one was for Big Think. One is the universe in under two minutes. So you can look up online, look for Lawrence Krauss explains the universe in under two minutes where I talk about this cosmic expansion and how it might mean there's a multiverse. But the other is I explained the universe in terms of this beer bottle that I talked about to you earlier. So that's a video. You can watch that. But this theory of inflation, which actually says the qualities that we see of our universe can best be explained at some early time in the history of the universe when it was a billionth of a billionth of a billionth of a billionth of a second old. It had a huge expansion suddenly and increased in size by 30 orders of magnitude in size in a billionth of a billionth of a billionth of a billionth of a second. Which is, by the way, particle physics suggests is highly plausible. And then it would produce a universe that looks more or less like we look like we look like. And it's right now the only explanation of how that would cause the universe to look like what it looks like. But the neat thing about inflation is it's eternal. So inflation, that puffing up ended in our universe and then boom, a hot big bang followed it. So the universe puffed up by a huge amount and all of that energy which was stored in empty space got released like the beer bottle and we got a hot big bang and the rest is history. But that's locally. But somewhere else between us and there, space is still expanding exponentially and faster and faster and faster. And only maybe somewhere else today, boom, like an ice crystal forming, boom, that region of space is suddenly left inflation. And maybe a gazillion years in the future there'll be another region of space that's expanding away from us so much faster than light so we'll never know about it. Where suddenly that region leaves inflation and boom, another hot big bang happens. And it turns out in each of those hot big bangs after the inflation ends, depending upon how it ends, the laws of physics could be different in that universe. And that's what we tend to think it's quite likely that there are many, many separate regions of space and in fact it's eternal. So such regions are forming eternally for all time. And there are hot big bangs happening in many regions and the properties of each of those regions, whether they're conducive to forming galaxies and stars and planets and people may be different. So we could say logically in that picture that the reason the universe looks like the way it does is because we're here to measure it. Oh my God, we should leave it at that. We should close with that. That is the mind blower of mind blowers. That is the mind blower of mind.