Ard: Many of the scientists that we speak to – in fact, I myself in my own research – think that beauty is a guide to truth in science. So, historically, many of the great scientists, like Dirac…

AR: Elegance.

Ard: Elegance and truth…

AR: Well the Dirac case is quite interesting if you’re thinking about the positron, but go on.

Ard: It was just… we interviewed Frank Wilczek, who has a whole book on this topic.

AR: Yes.

Ard: And there’s a classic argument that beauty is in some sense a guide to truth. What do you make of these arguments?

AR: So to begin with, where does our sense of beauty come from? It’s actually very interesting. There’s been some very nice studies about this, and our sense of beauty and of symmetry actually comes from the very bucolic, pleasing character of the sunset on the African savanna, or something rather like that.

But, for me, beauty, like simplicity, and other features of scientific theory are important, and they’re importance is justified largely by our inductive practices. That is to say, it has turned out in the past that those theories that are the simpler have proved to have been more well confirmed than the more complicated theories. And so we have a conviction in science that simpler is better than complicated, and we seek simpler theories.

Beauty alone is not going to be a substitute for, or treated as an invariable guide to truth: it’s just a general feature of many of the best scientific theories. Now, ask yourself why? That’s going to require an explanation, and that explanation may or may not be beautiful.

Ard: I’m wondering why. What do you think?

AR: I don't know the answer to that question. Probably because the universe… I’m inclined to think it’s because of reductionism. It’s because the universe is simple at its basement level, and because the principles of aggregation, of putting things together, are relatively simple, and so the outcomes tend to be simple.

Why is the universe simple? That’s a question for science too. We don’t even have a good metric for simplicity, still less a good metric for beauty, for us to actually be confident that more beautiful theories are, in fact, more well confirmed.

Ard: And do you think this question, of why is the universe simple, leads quickly to the kind of famous questions about why is there something…

AR: Rather than nothing? I don’t think that it does, but that’s an interesting question to which I think the sciences give an answer.

Ard: Which is what?

AR: No reason at all.

Ard: No reason at all?

AR: Quantum mechanics tells us that constantly, in this room, at every fire detector in this room, events are happening with no cause whatsoever, millions of times a second. Why shouldn’t the universe have come into existence on the same basis?

Ard: So you’re saying, why shouldn’t quantum mechanics itself have come into existence on the same basis?

AR: Quantum mechanics doesn’t come into existence. It’s a set of laws about reality. Are they the only set of laws about reality? Are they the set of laws at this universe as opposed to other universes in the multiverse? Well, let’s wait until we have established superstring theory.

Ard: Sure.

AR: And then we’ll be able to answer these questions. And until we do, anything else is just theology or speculation.