There Was a Universe Before the Big Bang | Roger Penrose, Claudia de Rham, and Karen Crowther

So the argument is, and my argument has been for a long time, that the age of the universe, well, it could be infinite. It's not the age since the Big Bang, because the Big Bang was not the beginning. Does the age of the universe represent a fundamental challenge to cosmology, and would an ageless universe upend our current account of the cosmos? Roger, if you could address that in the next three minutes, I'd be delighted. I think if people talk about the age of the universe, they usually mean the time from the Big Bang to now. Now, my view is that that's not the age of the universe, because the Big Bang was not the beginning. I think ever since about 2005 or so, I've been promoting an idea which in recent years has gained a certain account which is in favour of it, which maybe people don't know about. This is an observation due to Alexia Lopez, who was a graduate student—I think she's now graduated—and she was a graduate student in Lancashire, in this country, and she noticed there were certain very, very distant galaxies which formed, first of all, a big arc, and then secondly she found a ring. The big arc, she told me in an email correspondence, that she believes is actually a ring too. So these are also two rings which are so big in the sky that, according to conventional cosmology, they shouldn't be there, because they're sort of older than the age of the universe, if you like. When I heard about it, I thought, my goodness, that is a consequence or a prediction of the theory that I was putting forward but that nobody had ever predicted. It's a prediction of a theory in the sense that theory does predict it. These are rings of galaxies which are of enormous size and they don't fit into current conventional cosmology. So the argument is—and my argument has been for a long time—that the age of the universe could be infinite. It's not the age since the Big Bang, because the Big Bang is not the beginning. You have to understand how it could be. Our remote future will not be the end either. There will be a Big Bang following us, of the people after us. Thank you, Roger. Claudia, what's your opinion on this matter? It's probably one of the deepest questions of humanity, so I'm not sure we're going to address it in three minutes. Maybe give me four. As Roger very beautifully introduced, I think there's really two aspects of those questions that can be addressed in parallel. One of it is whether there is something before the Big Bang, whether the universe really started at the Big Bang, or whether the universe is timeless in that sense. Even understanding what the notion of time means when our best model for space and time, which is general relativity, breaks down, this is almost a philosophical question in itself. But we're starting to have tools to address that. I'm not going to do this in 30 seconds, but there's another part of the question which is related to the crisis. The crisis in cosmology, the crisis in our understanding, computing the age of the universe since the Big Bang, assuming let's say this is time zero, and then what is the age of the universe? Calling it a crisis is probably a little bit sensational. What is happening at the moment is that we're having different probes for determining the rate of accelerated expansion of the universe. From the evolution of the universe that we are measuring, we can trace it back to when this time of the Big Bang should have started. Now if we're looking at different probes, if we're looking at different physical systems with different instruments, just think of looking at things closer by or things further away, at the moment we're getting some estimation for the accelerated rate of the universe, what we call the Hubble rate of accelerated expansion of the universe, which is getting different and significantly more different in the way we compute things. Whether this is a real crisis points down to the fact that we should include new physics to understanding what happens in the evolution of the universe, or whether this is related more to understanding better the uncertainties in the different ways we probe the evolution of the universe. I think it's a little bit too early to say, so I wouldn't go up and down saying there's a huge crisis, but there's definitely something to understand out there and this is really what is exciting. Interesting, okay. Karen, what do you think about this age of the universe representing a fundamental challenge to cosmology? Yeah, so actually I'm a bit skeptical of the question itself. I'm here as the representative philosopher, so I'm going to question the question. I'm not sure it makes sense to ask about the age of the universe. So we can ask about the age of stuff in the universe, this is a question that makes sense to ask and conveniently it's also a question we know how to answer. We can make measurements of the matter and radiation, stars and galaxies, and from these different sources of data and our best theories of physics, we can work out the age of the stuff in the universe. But what about the universe itself? There's nothing outside of it, by definition, it's everything. So how do we measure it? How can we even ask anything about? I think it makes more sense to just say it exists, it just is. It's ageless, right? Like Mick Jagger, I think, or Roger here, he's ageless. So yeah, I don't believe in creation, I don't think we can get something from nothing, nothing comes from nothing. So the universe just is, it exists. But I think an interesting question coming from quantum gravity is maybe the universe doesn't have a beginning, it just exists, but maybe time hasn't always existed. Maybe space and time come into existence at some point and then that's what we mean about our universe, the spatio-temporal one. So a distinction between what we mean by our universe and the universe itself. But considering our universe in space-time, where did time begin? It didn't begin anywhere because the stuff before it was not spatio-temporal, it's not located anywhere. So can we ask about the age then? A bit difficult, nowhere to kind of start our watches. And on the other hand, this non-spatio-temporal, more fundamental universe, that doesn't even have time in it. So I think there's nowhere to ask about, does that have a birthday either? No, the question doesn't make sense. I'm already blown away, I don't even know what to do with that. Well, in that case, let's turn to the main theme that we were meant to start with here, which is to do with, is the age of the universe an absolute fact or is it a human construct based on the model of the universe that we adopt? I mean, Karen, I feel like that sort of naturally follows on from what you were just saying. So why don't you talk to that actually? Yeah, so exactly. There's different approaches towards finding this new theory of quantum gravity and they're suggesting different things. Several of them have this suggestion that space and time don't exist. And why do we need this theory of quantum gravity? Well, this is a good question, I just wrote a book about it. So it's not driven by kind of empirical problems really, it's driven by this kind of deep conceptual dissatisfaction in a way. We're believing that there are regimes where general relativity breaks down, for instance, at the Big Bang singularity. So we're dissatisfied with this, we want something more fundamental. And when we're trying to quantise space-time, we're ending up with something that's not space-time, it's more fundamental than space-time and somehow gives rise to it. So if you're working in quantum gravity, like I said, I think it's a bit of a strange question to ask. But once you move into the spatial temporal realm, of course, it's going to depend on your theories there. It's interesting. I mean, Claudia, so when it comes, I'm a cosmologist here, and when it comes to cosmology, it's quite precise what we mean by the age of the universe, which I think is important to specify, because if we say that there's a tension, if there's a disagreement, it's not a disagreement in how we phrase the question, it's a very precise level of disagreement where we can make progress into and try to understand better some signs of new physics. Now, when it comes to the age of the universe, there's different levels of questions. And I completely agree that understanding what it means, what happened at the Big Bang or before the Big Bang, if we think this is the beginning of time itself, is a meaningless question in and of itself. However, as cosmologists, we can ask the question, since how long did the Big Bang happen? And we can ask that question in a particular time clock. In fact, we have an evolution of the universe, and we have the cosmic mercury background, which we can think of representing a preferred observer in the universe. So each one of us can have a different perception of the flow of time and may be able to answer this question differently. But we can ask the question with respect to someone, something which is relatively universal for the universe, which is the cosmic microwave background. And in fact, the evolution of the universe sets up a preferred direction of the flow of time. So within that context, we can all agree on how we want to phrase our question, and all agree on how we're going to answer it. And if we come up with a number of 13.7 or 13.8 billion years, this is a very clear answer to that question. Now, when we come again to the crisis in the age of the universe, it is really because when we make different types of observations, we seem to be going down to slightly different values of that. And I think this is something not to be miffed upon. This is really something that may signal some new opportunity to understand how the universe has evolved, to understand what the universe is actually telling us. So in phrasing the question as what is the age of the universe, this is a way for us to, in fact, extract information that the universe wants to tell us. And there's something very enriching in doing so. So Claudia, can we actually test those theories at the sort of extreme parts of the universe, or are we limited to speculation under those contexts? Oh, so when it comes to what is the age of the universe, and answering that question, that doesn't necessarily rely on having a theory of quantum gravity. What relies on having a more fundamental theory of the very nature of space and time, and what happened before, or at the Big Bang, or if that question is even meaningful, that's when we really need to have a more fundamental theory of quantum gravity. And there's different possibilities out there. There's string theory, there's causal sets, there's loop quantum gravity, there's Hawking boundary proposals, all of those possibilities are there, with different flavours in how we want to test them. Some of them we can, some of them it will be more challenging. But the question is, if it's a question about what is the actual time lapse from the point of view of the cosmic microwave background that has elapsed since this time zero of the Big Bang to now, we can use a particular model, which is the best model, the lambda CDM, the cosmological constant plus cold dark matter framework, standard model of cosmology, to address that question. And if the answers that we get, depending on who we interrogate, which system, whether it's supernovae, whether it's the structure of the universe, whether it's the temperature of the sky, if those give us slightly different answers, then we need to expand on the cosmological framework. And in that case, we can test them. But the reality is a lot of the observations that we have at the moment do converge towards very specific values for these parameters of the cosmological paradigm. And this convergence in our observations from physics, which is vastly different. We're looking at systems which are explosions of stars with particular telescopes, with particular instruments. And then we're looking at the temperature of the sky when it was produced just a few years since the Big Bang. It's vastly different scales, vastly different instruments, vastly different physics that we're using to probe and ask ourselves the same question. And we're getting almost the same answer. They almost all seem to agree within some level of uncertainty. That in itself tells us that we must be doing something right. Okay, that's really interesting. Roger, I feel like you said something about this at the beginning, right? You said that the Big Bang is not the beginning. I would assume that you are also a Big Bang sceptic, like Karen here. I think I should comment further on this. I think most of the discussion we've been having on a pretty structured conservative, that is to say that the recent measurement of the age of the universe I would have no quibble with if they mean the age since the Big Bang. Now, there is evidence, as I mentioned previously, there already was, because various papers have been written about this. But the new evidence, we've been reading it in the sky, presents a real puzzle for conventional cosmology, because what they seem to indicate was that there was some event which took place before the Big Bang. Now, the theme I've been trying to promote for about 20 years, more than 20 years, the Big Bang was not the beginning. It was the continuation of the remote future of a previous cosmic eon. Now, you say, what could be more different than the remote future of our eon, or the previous eon, where you have a very, very expansion, keeps on going and going, the densities get less and less, and it becomes very, very rarefied, very, very cold. Whereas the Big Bang is very concentrated, very dense, and very, very hot. You could say, well, what could be more different? I would say they're very, very similar, because at both ends, in the remote future end and in the Big Bang end, you have a situation in which mass effectively disappears. Now, why do I say mass is important? Because mass is how we measure time. It's a combination of the two most famous formulas of 20th century physics, namely Einstein's equation, E equals mc squared, which tells us the energy and mass of equivalence, and even earlier, Max Planck's E equals h nu or hf, where nu or f is a frequency, and that tells us that energy and frequency are equivalent. If you put the two together, that tells you that mass and frequency are equivalent. That is to say, a mass, a particle, a massive particle is a clock. In fact, atomic and nuclear clocks are so precise because that's basically what they're using, and it's not exactly that, but it's essentially that. The mass is a ticking clock, a very, very high frequency, so you can't literally direct use it. However, it's the presence of mass which determines the scale, the time scale and the space scale. Now, in the remote future, mass basically fades away. You have mostly photons and the effect of ordinary massive particles. The mass also fades away, too, so that in the remote future, you have effectively a situation when there is no mass. The other side, if you go back to the Big Bang, particles are moving around so fast, the closer you get to the Big Bang, the faster they move, and that means the more irrelevant their mass is. The energy of their motion is almost entirely kinetic, and it has almost nothing to do with the mass of the particles. But the two ends, the remote future and the Big Bang, you have a situation in which times the scale of things gets lost. So what I'm saying is that it makes sense. In fact, it makes a lot of sense, and there's observation and evidence in favor of this. The paper that I wrote with a couple of colleagues agreed me to give a phenomenon which the theory predicts, and it was given a confidence level of 99.98 percent. Do people pay attention to it? Not really, because they're skeptical of the model which I'm promoting. The model says that the remote future becomes—it loses track of scale of things because mass becomes unimportant—fades out completely, and then you have a crossover into the next, what I call, eon, the next cosmic eon, which has its Big Bang. The remote future of our cosmos, our eon—I'm going to call it cosmic eon—becomes the Big Bang of the next one, and our Big Bang was the remote future of a previous one. Now, there are effects which come through, and the most recent one is a very striking observation. To continue watching this video, click the link in the top left or in the description.