David: Why the title of the book? It’s such a lovely title. What was it that drew you to that title?

FW: Well, the more I thought about what I was doing in the book – this exploration of how it comes to be that our perception of the world at a deep level matches our perception of beauty – it became… it’s a puzzle. And the more I thought about it, the more it resonated, and the more I realised that, first of all, I have been worrying about the beauty of quantum theory and the beauty of the deep descriptions of nature all my adult life, and even before. So it was coming to terms with myself and what I had been doing all of those years.

David: You used the word ‘worry’: ‘I had been worrying about this.’ Why would beauty be something that would be a worry to a physicist?

FW: Well, because it’s not accomplished. We have a lot of beauty in our description of the world but also a lot of loose ends. Also it poses a deep mystery. Why should it be that way? Beauty is one thing and the way the world works is quite another. In fact, often when I start discussing this with people, they’re very puzzled. Beauty is this subjective feeling that people have, whereas science is objective: they couldn’t be more different, and yet many physicists and philosophers, for that matter, and artists, who have come into deep relationships with the natural world, have been delighted at its beauty. So it’s a common experience, and almost universal among modern physicists working on fundamental physics that they feel the structure they find is beautiful. So why should that be?

Ard: I think that’s a common view, isn’t it, that beauty is merely subjective? It’s in the eye of the beholder, and so what I find beautiful might be different to what you find beautiful, and so what’s really surprising is that this subjective feeling has traction on the physical world.

FW: Yes, well I think beauty is a word that is used for many things. I think what they have in common is that beautiful things, beautiful experiences, are things we want to come back to: they are things we find rewarding.

Much of my anticipation of what the laws might look like, and guessing of new laws, was based on an instinct for a kind a beauty, and it’s worked, so far. There’s some cases still out to jury, but some cases have definitely worked, and so it’s changed my life.

Ard: Is that what drew you to physics in the first place? That sense of beauty? Do you think that’s what made you interested in it?

FW: Ah, well, when I first was drawn to it, I didn’t really know how beautiful it was going to be, but if I think back on my childhood, my earliest memories have to do with taking things apart and putting them together. I was very much a student of mathematics, so I always had a feeling for that kind of beauty. The fact that it was abstract, which turns off many people, it didn’t turn me off because it allowed more freedom in manipulation, so to speak. And the fact that this particular kind of thinking is actually what gives you a deep understanding of the physical world: that’s a tremendous gift I can only be grateful for and sort of contemplate in awe. But that leaves a different question, which is: why are the laws comprehensible?

David: Yes, why can we understand them at all?

FW: If they weren’t beautiful, we wouldn’t find them. But why did we have to find them? Well that one I’m still working on… I don’t know. It’s just a gift.