There's no way that scientists can ever rule out religion, or even have anything significant to say about the abstract idea of a divine creator.

Most scientists like to operate in the context of economy. If you don't need an explanatory principle, don't invoke it.

The bottom line is that time travel is allowed by the laws of physics.

The melded nature of space and time is intimately woven with properties of light speed. The inviolable nature of the speed of light is actually, in Einstein's hands, talking about the inviolable nature of cause and effect.

I may be a Jewish scientist, but I would be tickled silly if one day I were reincarnated as a Baptist preacher.

I think it's too fast to say that all sci-fi ultimately winds up having some place in science. On the other hand, imaginative minds working outside of science as storytellers certainly have come upon ideas that, with the passing decades, have either materialized of come close to materializing.

The idea that there could be other universes out there is really one that stretches the mind in a great way.

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.

I would say in one sentence my goal is to at least be part of the journey to find the unified theory that Einstein himself was really the first to look for.

Intelligence is the ability to take in information from the world and to find patterns in that information that allow you to organize your perceptions and understand the external world.

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

String theory envisions a multiverse in which our universe is one slice of bread in a big cosmic loaf. The other slices would be displaced from ours in some extra dimension of space.

We know that if supersymmetric particles exist, they must be very heavy; otherwise we would have spotted them by now.

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.

Our eyes only see the big dimensions, but beyond those there are others that escape detection because they are so small.

My emotional investment is in finding truth. If string theory is wrong, I'd like to have known that yesterday. But if we can show it today or tomorrow, fantastic.

My mom says: 'Why aren't you a doctor?' and I'm like, 'I am a doctor!' and she's all, 'No, I mean a real doctor.' She reads my books, but she says they give her a headache.

String theory has the potential to show that all of the wondrous happenings in the universe - from the frantic dance of subatomic quarks to the stately waltz of orbiting binary stars; from the primordial fireball of the big bang to the majestic swirl of heavenly galaxies - are reflections of one, grand physical principle, one master equation.

A unified theory would put us at the doorstep of a vast universe of things that we could finally explore with precision.

If the theory turns out to be right, that will be tremendously thick and tasty icing on the cake.

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?

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

How can a speck of a universe be physically identical to the great expanse we view in the heavens above?

I have long thought that anyone who does not regularly - or ever - gaze up and see the wonder and glory of a dark night sky filled with countless stars loses a sense of their fundamental connectedness to the universe.