All you are is a bag of particles acting out the laws of physics. That to me is pretty clear.

We can certainly go further than cats, but why should it be that our brains are somehow so suited to the universe that our brains will be able to understand the deepest workings?

General relativity is in the old Newtonian framework where you predict what will happen, not the probability of what will happen. And putting together the probabilities of quantum mechanics with the certainty of general relativity, that's been the big challenge and that's why we have been excited about string theory, as it's one of the only approaches that can put it together.

We're on this planet for the briefest of moments in cosmic terms, and I want to spend that time thinking about what I consider the deepest questions.

Supersymmetry is a theory which stipulates that for every known particle there should be a partner particle. For instance, the electron should be paired with a supersymmetric 'selectron,' quarks ought to have 'squark' partners, and so on.

The boldness of asking deep questions may require unforeseen flexibility if we are to accept the answers.

Physics grapples with the largest questions the universe presents. Where did the totality of reality come from? Did time have a beginning?