Roger Penrose: Infinite Cycles of the Universe Punctuated by Big Bang Singularities

But where does the conformal cyclic cosmology of starting to talk about something before that singularity?

Well, I began, I was just thinking to myself how boring this universe is going to be. You've got this exponential expansion. This was discovered early in this century. 21st century people discovered that these supernova exploding stars showed that the universe is actually undergoing this exponential expansion. So it's a self similar expansion. And it seems to be a feature of this term that Einstein introduced into his cosmology for the wrong reason. He wanted a universe that was static. He put this new term into his cosmology to make it make sense. It's called the cosmological constant. And then when he got convinced that the universe had a big bang, he retracted it, complaining this was his greatest blunder. The trouble is it wasn't a blunder. It was actually right. Very ironic. And so the universe seems to be behaving with this cosmological constant. Okay, so this universe is expanding and expanding. What's going to happen in the future? Well, it gets more and more boring for a while. What's the most interesting thing in the universe? Well, there's black holes. The black holes more or less gulp down entire clusters of galaxies. It'll swallow up most of our galaxy. We will run into Andromeda galaxy's black hole. That black hole will swallow our one. They'll get bigger and bigger and they'll basically swallow up the whole cluster of galaxies. Gulp it all down pretty well all. Most of it, maybe not all, most of it. And then that'll happen to. There'll be just these black holes around. Pretty boring, but still not as boring as it's going to get. It's going to get more boring because these black holes, you wait, you wait and you wait and you wait and wait an unbelievable length of time. And Hawking's black hole evaporation starts to come in and the black holes, you just, it's incredibly tedious. Finally evaporate away. Each one goes away, disappears with a pop at the end. What could be more boring? That it was boring then, now this is really boring. There's nothing, not even black holes. Universe gets colder and colder and colder and colder. And I thought, this is very, very boring. Now that's not science, is it? But it's emotional. So I thought, who's going to be bored by this universe? Not us. We won't be around. It'll be mostly photons running around. And what do photons do? They don't get bored because it's part of relativity. You See, it's not really that they don't experience anything. That's not the point. Photons get right out to infinity without experience any time. It's the way relativity works. And this was part of what I used to do in my old days when I was looking at gravitational radiation and how things behave. Infinity. Infinity is just like another place. You can squash it down as long as you don't have any mass in the world. Infinity is just another place. The photons get there, the gravitons get there. What do they get? They run to infinity. They say, well, now I'm here. What do I. There's something on the other side. Is there the usual view? It's just a mathematical notion. There's nothing on the other side. That's just the boundary of it. A nice example is this beautiful series of pictures by the Dutch artist MC Escher. You may know them, the ones called circle limits. They're very famous. One with the angels and the devils. And you can see them crowding and crowding and crowding up to the edge. Now, the kind of geometry that these angels and devils inhabit, that's their infinity. But from our perspective, infinity is just a climb. It's a place. Okay, there is.

Sorry, can you just take a brief pause?

Yes.

And just the word you're saying. Infinity is just a place. So for the most part, infinity, sort of even just going back. Infinity is a mathematical concept.

I think this is one.

You think there's an actual physical manifest. Like, in which way does infinity ever manifest itself in our physical universe?

Well, it does in various places. You see, it's a thing that if you're not a mathematician, you think, oh, infinity. I can't think about that. Mathematicians think about affinity all the time. They get used to the idea and they just play around with different kinds of infinities and it becomes no problem. But you just have to take my word for it. Now, one of the things is, you see, you take a Euclidean geometry, well, it just keeps on, keeps on, keeps on going, and it goes out to infinity. Now, there's other kinds of geometry, and this is what's called hyperbolic geometry. It's a bit like Euclidean geometry. It's a little bit different. It's like what Escher was trying to describe in his Angels and Devils, and he learned about this from Coxeter, and he think, that's a very nice thing. I try and represent this infinity to this kind of geometry. So it's not quite Euclidean geometry. It's a bit like it that the angels and the devils inhabit and their infinity. By this nice transformation, you squash their infinity down so you can draw it as this nice circle boundary to their universe. Now, from our outside perspective, we can see their infinity as this boundary. Now, what I'm saying is that it's very like that the infinity that we might experience, like those angels and devils in their world, can be thought of as a boundary. Now, I found this a very useful way of talking about radiation, gravitational radiation and things like that. It was a trick, mathematical trick. So now what I'm saying is that that mathematical trick becomes real, that somehow the photons, they need to go somewhere because from their perspective, infinity is just another place. Now, this is a difficult idea to get your mind around. So that's why one of the reasons cosmologists are finding a lot of trouble taking me seriously. But to me, it's not such a wild idea what's on the other side of that infinity. You have to think, why am I allowed to think of this? Because photons don't have any mass, and we in physics have beautiful ways of measuring time. They are incredibly precise clocks, atomic and nuclear clocks, unbelievably precise. Why are they so precise? Because of the two most famous equations of 20th century physics. One of them is Einstein's E equals MC squared. What's that tell us? Energy and mass are equivalent. The other one is even older than that, still 20th century, only just. Max Planck. E equals H nu. Nu is a frequency. H is a constant. Again, like C. E is energy. Energy and frequency are equivalent. Put the two together. Energy and mass are equivalent. Einstein, energy and frequency equivalent. Max Black put the two together. Mass and frequency are equivalent. Absolutely. Basic physical principle. If you have a massive entity, a massive particle, it is a clock with a very, very precise frequency. It's not you can't directly use it. You have to scale it down. So your atomic and nuclear clocks. But that's the basic principle. You scale it down to something you can actually perceive. But it's the same principle. If you have mass, you have beautiful clocks. But the other side of that coin is if you don't have mass, you don't have clocks. If you don't have clocks, you don't have rulers, you don't have scale.

So you don't have space and time.

You don't have a measure of the scale of space and time. You do have the structure, what's called the conformal structure. You see, it's what the angels and devils have. If you look at the eye of the devil, no matter how Close to the boundary it is. It has the same shape, but it has a different size. So you can scale up and you can scale down, but you mustn't change the shape. So it's basically the same idea, but applied to space time. Now, in the very remote future, you have things which don't measure the scale, but the shape, if you like, is still there. Now, that's in the remote future. Now I'm going to do the exact opposite. Now I'm going to go way back into the Big Bang. Now, as you get there, things go hotter and hotter, denser and denser. What's the universe dominated by? Particles moving around almost with the speed of light. When they get almost with the speed of light, okay. They begin to lose the mass too. So for a completely opposite reason, they lose the sense of scale as well. So my crazy idea is the Big Bang and a remote future. They seem completely different. One is extremely dense, extremely hot. The other is very, very rarefied and very, very cold. But if you squash one down by this conformal scaling, you get the other. So although they look and feel very different, they're really almost the same. The remote future on the other side, I'm claiming, is that where do the photons go? They go into the next Big Bang. You've got to get your mind around that crazy idea.

Taking a step on the other side of the place that is infinity. Okay, but so I'm saying the other.

Side of our Big Bang. Now I'm going back into the Big Bang. Back. That was the remote future of a previous eon.

Previous eon.

And what I'm saying is that previous eon, there are signals coming through to us which we can see and which we do see. And these are both signals. The two main signals are to do with black holes. One of them is the collisions between black holes. And as they spiral into each other, they release a lot of energy in the form of gravitational waves. Those gravitational waves get through in a certain form into the next eon.

That's fascinating that there's some. I mean, maybe I'm. Maybe you can correct me if I'm wrong, but that means that some information can travel.

Yes.

From another eon.

Exactly.

That. That is fascinating. I mean, I've seen somewhere, described sort of the discussion of the Fermi paradox, you know, that if there's intelligent life.

Yes.

Being, you know, communication immediately takes you there.

We have a paper, my colleague, Vahe Gurzajan, who I worked with on these ideas for a while. We have a crazy paper on that. Yes. Looking at the Fermi paradox. Yes.

Right. So if the universes are just cycling over and over and over, punctuated by the. Punctuated the singularity of the Big Bang, and then intelligent or any kind of intelligent systems can communicate through from eon to eon, why haven't we heard anything from our alien friends?

Because we don't know how to look.

That's fundamentally the reason.

I don't know. You see, it's speculation. I mean, the SETI program is a reasonable thing to do, but still speculation. It's trying to say, okay, maybe not too far away with a civilization which got there first before us, early enough that they could send us signals. But how far away would you need to go before. I mean, I don't know. We have so little knowledge about that we haven't seen any signals yet. But it's worth looking. It's worth looking. What I'm trying to say. Here's another possible place where you might look now. You're not looking at civilizations which got there first. You're looking at those civilizations which were so successful, probably a lot more successful than we're likely to be by the looks of things, which knew how to handle their own global warming or whatever it is, and to get through it all and to live to a ripe old age in the sense of a civilization to the extent that they could harness signals that they could propagate through for some reason of their own desires, whatever, we wouldn't know, to other civilizations which might be able to pick up the signals. But what kind of signals would they be? I haven't the foggiest.