A watch worn by a particle of light would not tick at all. Light realizes the dreams of Ponce de Leon and the cosmetics industry: it doesn't age.

In quantum mechanics there is A causing B. The equations do not stand outside that usual paradigm of physics. The real issue is that the kinds of things you predict in quantum mechanics are different from the kinds of things you predict using general relativity. Quantum mechanics, that big, new, spectacular remarkable idea is that you only predict probabilities, the likelihood of one outcome or another. That's the new idea.

I like to think that Einstein would look at string theory’s journey and smile, enjoying the theory’s remarkable geometrical features while feeling kinship with fellow travelers on the long and winding road toward unification.

I think the relationship between memory and time is a very deep and tricky one, to tell you the truth. I don't consider memory another sense. I do consider memory that which allows us to think that time flows.

We do not know whether there are extra dimensions or multiverse. Let's go forward with the possible ideas that come out of the mathematics. It's hard for us to imagine a universe that would have no time at all.

No matter how hard you try to teach your cat general relativity, you're going to fail.

I love it when real science finds a home in a fictional setting, where you take some real core idea of science and weave it through a fictional narrative in order to bring it to life, the way stories can. That's my favorite thing.