Is the Universe Fine-Tuned for Life and Mind? | Roger Penrose

Roger, the apparent fine-tuning of the universe is one of the hottest and indeed most controversial topics in our intellectual life today. Among physicists argue about it among each other, philosophers, theologians, and then philosophers, theologians, and physicists all together. I want to get your sense, first of all, about the legitimacy of the question in terms of is the universe fine-tuned, particularly the initial condition? Well, the universe is certainly fine-tuned in the sense that the initial state of the universe was extraordinarily special. Now usually when people talk about this fine-tuning, they're talking about something quite different. They refer to the constants of nature, which could conceivably have quite different values. One of the most obvious ones is the relationship between the gravitational electromagnetic electric force. So you take the force between a proton and an electron and a hydrogen atom, and there's a number with about 40 zeros. But I'm not altogether convinced by these. It could well be that there is special fine-tuning in these numbers, which is necessary for life. It's certainly the case that if these numbers had different values, and sometimes not very different values, then life as we know it couldn't have happened. But that doesn't mean that some kind of life or some kind of consciousness, which is really what you need because of conscious being in these anthropic arguments, you say, well, how could consciousness have arisen? That's the key point. Since we have such little understanding of what consciousness is and what's the necessary prerequisite for consciousness, the argument is a genuine one, it's a genuine question, but it's so far from being able to be answered that I really see it's almost unusable in most circumstances. There are a few cases where I think it's usefully usable, but the trouble is we know so little about the circumstances which are necessary for life. For other kinds of life. Yeah. I mean, other kinds of life. Yes, our own kind. We know. But that's all we know, and we're biased to thinking about it in those terms. So the fine-tuning is fine-tuning for our life, but that doesn't mean that other kinds of tunes can play other kinds of lives. Exactly. There could be something completely different. And in any case, conscious or intelligent life is probably extremely rare. I mean, it's not all that well suited to it, you see. And in any case, it could be that it could have come about in completely different ways. Now there's fine-tuning in the origin of the universe, which has to do with the second law of thermodynamics. It has to have been extraordinarily precise, and in fact, it has to have been at least as precise as one part in 10 to the power, 10 to the power, 123. Now that's ridiculous. It's an extraordinary number. It's a ridiculous number, yes. That's right. And it's nothing like, people worry about the constants of nature, you see. You want to fix those constants. Okay, they're just a few numbers, 20 numbers maybe. And those have got to be fixed through, I don't know, just a certain amount of precision. And that's nothing by comparison with this number. The precision that we see in the initial state of the universe completely dwarfs any of these other considerations. Now, what does that really mean, though, that precision in the initial condition, based on the second law? Well, what it means is that the anthropic argument is useless for explaining it. I mean, in this context, it may mean all sorts of other things, but in this context, it's telling us that the anthropic argument is absolutely useless for telling us why that number is so precise, why the universe was so precise. I mean, if it was, that number is so, the precision is so incredibly enormous because you have to do it for the whole universe. If you just had to do it for our solar system or for our galaxy, the number would be ridiculously smaller. And that's all we need. We don't need the universe as it keeps on going and keeps on going and keeps on going. But it's there. We're given it. We don't need it for us. So the anthropic argument is no, gets nowhere, absolutely nowhere close to explaining that. It has to be a completely different kind of explanation. Now, maybe the anthropic argument has something useful to say about the constants of nature, but it's so hard really to use it just because we don't have much understanding of what life is or what consciousness is. But going back to the initial condition and the incredible specificity that the universe had to have. I mean, that's our universe. Yeah. I mean, that's the one we... If we're going to explain existence, which is we're here in this existence, that's the one we got, right? That's right. Absolutely. So we got to explain it. Absolutely. How do we do it? I completely agree. But it's not the anthropic argument. That's what I'm saying. Well, then what is it? Well, it's... I have various ideas about this. I mean, you can make a hypothesis of a certain kind, which is something I have put forward. I referred to as the vial curvature hypothesis, which is saying that the space-time curvature in the initial stages of the universe has to have been of a very particular kind. But that's just a hypothesis. The usual view is that some form of quantum gravity or whatever it is has to explain why that comes out. And that level of precision is so impossible to conceive of as from some random point of view. I mean, that's not something that you can achieve in a random fashion under any... I mean, in infinity, you can do anything, obviously, but that's... It's no explanation. I mean, that's right. I mean, you can't say, well, there are lots of universes, and out of that particular one, which we happen to be in, that number was that thing. Well, no, it doesn't explain it. You don't get anywhere close to that number. What is the implication, then, in terms of the generation of such incredible precision? Can the argument of multiple universes achieve that? Well, I don't think any of these are going to... It's such an improbable... We're talking about how special the Big Bang was. Now, you could imagine other Big Bangs, which weren't so special, but, I mean, you can have other Big Bangs not so special, but that's not what we've got, you see. And we're here in this one. We're here in this one. We could have been here equally well in zillions of the other ones, you see, which weren't so special. You could have a universe which is special in our neighborhood. Our galaxy could be just as it is, but the distant universe would be different and not special out there. And that's much more likely, if you're just talking about probabilities. All these other alternatives are far more likely than the one we see. It's just... All I'm saying is that the anthropic argument, which is saying we're here and that's why the universe is as special as we see it, doesn't go anywhere to explaining the specialness of the Big Bang. Okay, it might have something to say about these few constants of nature, which we have trouble explaining why they fit together in certain ways. But that's chicken feed, my comparison with the special nature of the Big Bang. And the anthropic argument gets you nowhere. It's just... It gets you nowhere because we don't need the universe to be that special for us. It's not any use to us at all why the distant universe is incredibly special and why it came from the Big Bang, which is just part of the Big Bang, which is just as special as the part we came from. And you can't say... Another argument, you can't say, well, okay, there's... You could have got lots more people by having a bigger universe. That doesn't work either because there's lots of cheaper ways of making lots more people. You make lots of universes. It's far cheaper in the sense of improbabilities, let's just say it's far more probable, to make lots of universes with a few people in each one than to make one universe full of people. And that's just a simple way of saying... In a sense, this is an even deeper mystery than the anthropic people normally put out for us. Yes, it is. Yes. No, it needs a scientific explanation. It needs a good physical theory to say why the Big Bang had that nature that it did. And we have no theory which really explains that. I mean, people usually say it's quantum gravity. No quantum gravity theory I've ever seen incorporates the asymmetry in time which is necessary to explain why the Big Bang had this special nature and not the singular states which come from black holes, collapses, and so on. There has to be something asymmetrical because the second law of thermodynamics is asymmetrical. And any quantum gravity theory which is going to explain why the Big Bang has this special structure has got to have that in it. And no theory I've ever seen has that character.