In a vacuum all photons travel at the same speed. They slow down when travelling through air or water or glass. Photons of different energies are slowed down at different rates. If Tolstoy had known this, would he have recognised the terrible untruth at the beginning of Anna Karenina? 'All happy families are alike; every unhappy family is unhappy in its own particular way.' In fact it's the other way around. Happiness is a specific. Misery is a generalisation. People usually know exactly why they are happy. They very rarely know why they are miserable.

One thing I am certain of, I do not want to be betrayed, but thats quite hard to say casually, at the beginning of a relationship. It’s not a word people use very often, which confuses me, because there are different kinds of infidelity, but betrayal is betrayal wherever you find it. By betrayal, I mean promising to be on your side, and then being on somebody else’s.

The curious are always in some danger. If you are curious you might never come home.

We're in a strange situation where people either don't read at all or they read a lot. There's a huge gap in between. That's something that would be good to bridge so it doesn't have to be one thing or the other. Books could be part of life in a more relaxed way. I'd like to see that.

Happy Valentines Day to those who have found love, in whatever shape or form, and to those who are still hunting, don't give up. If you feel bad, send yourself a card. You must be worth it.

Do you fall in love often?" Yes often. With a view, with a book, with a dog, a cat, with numbers, with friends, with complete strangers, with nothing at all.

The fact is that every atom that we're made of is part of that first explosion of a nuclear star billions of years ago. We're connected to the entire universe.