It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.

My goal is simple. It is a complete understanding of the universe, why it is as it is and why it exists at all.

There are grounds for cautious optimism that we may now be near the end ofthe search for the ultimate laws of nature.

Someone told me that each equation I included in the book would halve the sales.

Intelligence is the ability to adapt to change.

It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.

I have noticed even people who claim everything is predestined, and that we can do nothing to change it, look before they cross the road.

We are just an advanced breed of monkeys on a minor planet of a very average star. But we can understand the Universe. That makes us something very special.

The usual approach of science of constructing a mathematical model cannot answer the questions of why there should be a universe for the model to describe. Why does the universe go to all the bother of existing?

One cannot really argue with a mathematical theorem.

The whole history of science has been the gradual realization that events do not happen in an arbitrary manner, but that they reflect a certain underlying order, which may or may not be divinely inspired.

To confine our attention to terrestrial matters would be to limit the human spirit.

If we do discover a complete theory, it should be in time understandable in broad principle by everyone. Then we shall all, philosophers, scientists, and just ordinary people be able to take part in the discussion of why we and the universe exist.

Not only does God play dice, but... he sometimes throws them where they cannot be seen.

Most sets of values would give rise to universes that, although they might be very beautiful, would contain no one able to wonder at that beauty.

I think computer viruses should count as life. I think it says something about human nature that the only form of life we have created so far is purely destructive. We've created life in our own image.

God not only plays dice, He also sometimes throws the dice where they cannot be seen.

Even if there is only one possible unified theory, it is just a set of rules and equations. What is it that breathes fire into the equations and makes a universe for them to describe?

It is not clear that intelligence has any long-term survival value.

'The Simpsons' appearances were great fun. But I don't take them too seriously. I think 'The Simpsons' have treated my disability responsibly.

A few years ago, the city council of Monza, Italy, barred pet owners from keeping goldfish in curved bowls... saying that it is cruel to keep a fish in a bowl with curved sides because, gazing out, the fish would have a distorted view of reality. But how do we know we have the true, undistorted picture of reality?

A zero-gravity flight is a first step toward space travel.

According to 'M' theory, ours is not the only universe. Instead, 'M' theory predicts that a great many universes were created out of nothing.

All my adult life people have been helping me.

Although September 11 was horrible, it didn't threaten the survival of the human race, like nuclear weapons do.

Although almost every theoretical physicist agrees with my prediction that a black hole should glow like a hot body, it would be very difficult to verify experimentally because the temperature of a macroscopic black hole is so low.

Among physicists, I'm respected I hope.

As Irving Good realised in 1965, machines with superhuman intelligence could repeatedly improve their design even further, triggering what Vernor Vinge called a 'singularity.'

As scientists, we step on the shoulders of science, building on the work that has come before us - aiming to inspire a new generation of young scientists to continue once we are gone.

Because there is a law such as gravity, the universe can and will create itself from nothing.

Before 1915, space and time were thought of as a fixed arena in which events took place, but which was not affected by what happened in it. Space and time are now dynamic quantities... space and time not only affect but are also affected by everything that happens in the universe.

Cambridge is one of the best universities in the world, especially in my field.

Computers double their performance every month.

Cosmology is a rapidly advancing field.

Earth might one day soon resemble the planet Venus.

Even if it turns out that time travel is impossible, it is important that we understand why it is impossible.

Evolution has ensured that our brains just aren't equipped to visualise 11 dimensions directly. However, from a purely mathematical point of view it's just as easy to think in 11 dimensions, as it is to think in three or four.

Exploration by real people inspires us.

For years, my early work with Roger Penrose seemed to be a disaster for science. It showed that the universe must have begun with a singularity, if Einstein's general theory of relativity is correct. That appeared to indicate that science could not predict how the universe would begin.

God is the name people give to the reason we are here. But I think that reason is the laws of physics rather than someone with whom one can have a personal relationship. An impersonal God.

God not only plays dice, but also sometimes throws them where they cannot be seen.

However difficult life may seem, there is always something you can do and succeed at.

I am in touch with a company that hopes to replicate my voice. However, they are not replicating my original voice - if they did that, I would sound like a man in his 20s, which would be very strange! They are actually trying to replicate the synthesizer that sits on my wheelchair.

I am just a child who has never grown up. I still keep asking these 'how' and 'why' questions. Occasionally, I find an answer.

I believe alien life is quite common in the universe, although intelligent life is less so. Some say it has yet to appear on planet Earth.

I believe everyone should have a broad picture of how the universe operates and our place in it. It is a basic human desire. And it also puts our worries in perspective.

I believe in universal health care. And I am not afraid to say so.

I believe the universe is governed by the laws of science. The laws may have been decreed by God, but God does not intervene to break the laws.

I believe things cannot make themselves impossible.