Success in creating AI would be the biggest event in human history. Unfortunately, it might also be the last, unless we learn how to avoid the risks.

I don't have much positive to say about motor neuron disease, but it taught me not to pity myself because others were worse off, and to get on with what I still could do. I'm happier now than before I developed the condition.

I don't have much positive to say about motor neurone disease. But it taught me not to pity myself because others were worse off, and to get on with what I could still do.

I believe things cannot make themselves impossible.

Some people would claim that things like love, joy and beauty belong to a different category from science and can't be described in scientific terms, but I think they can now be explained by the theory of evolution.

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.

Sometimes I wonder if I'm as famous for my wheelchair and disabilities as I am for my discoveries.

I regard the brain as a computer which will stop working when its components fail. There is no heaven or afterlife for broken down computers; that is a fairy story for people afraid of the dark.

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.

Computers double their performance every month.

There is a real danger that computers will develop intelligence and take over. We urgently need to develop direct connections to the brain so that computers can add to human intelligence rather than be in opposition.

There is no heaven or afterlife for broken-down computers; that is a fairy story for people afraid of the dark.

Look up at the stars and not down at your feet. Try to make sense of what you see, and wonder about what makes the universe exist. Be curious.

Time travel was once considered scientific heresy, and I used to avoid talking about it for fear of being labelled a 'crank.'

Science is increasingly answering questions that used to be the province of religion.

I'm not afraid of death, but I'm in no hurry to die. I have so much I want to do first.

I was born on January 8, 1942, exactly three hundred years after the death of Galileo. I estimate, however, that about two hundred thousand other babies were also born that day. I don't know whether any of them was later interested in astronomy.

Science is not only a disciple of reason but, also, one of romance and passion.

Science is beautiful when it makes simple explanations of phenomena or connections between different observations. Examples include the double helix in biology and the fundamental equations of physics.

Time travel used to be thought of as just science fiction, but Einstein's general theory of relativity allows for the possibility that we could warp space-time so much that you could go off in a rocket and return before you set out.

Science can lift people out of poverty and cure disease. That, in turn, will reduce civil unrest.

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.

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?

In the past, there was active discrimination against women in science. That has now gone, and although there are residual effects, these are not enough to account for the small numbers of women, particularly in mathematics and physics.

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.

I hope I have helped to raise the profile of science and to show that physics is not a mystery but can be understood by ordinary people.

God may exist, but science can explain the universe without the need for a creator.

Throughout history, people have studied pure science from a desire to understand the universe rather than practical applications for commercial gain. But their discoveries later turned out to have great practical benefits.

The universe is governed by science. But science tells us that we can't solve the equations, directly in the abstract.

I believe there are no questions that science can't answer about a physical universe.

Before we understand science, it is natural to believe that God created the universe.

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.

If you believe in science, like I do, you believe that there are certain laws that are always obeyed.

Science predicts that many different kinds of universe will be spontaneously created out of nothing. It is a matter of chance which we are in.

Philosophers have not kept up with modern developments in science. Particularly physics.

The media need superheroes in science just as in every sphere of life, but there is really a continuous range of abilities with no clear dividing line.

I used to think information was destroyed in black hole. This was my biggest blunder, or at least my biggest blunder in science.

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 have found far greater enthusiasm for science in America than here in Britain. There is more enthusiasm for everything in America.

Before I lost my voice, it was slurred, so only those close to me could understand, but with the computer voice, I found I could give popular lectures. I enjoy communicating science. It is important that the public understands basic science, if they are not to leave vital decisions to others.

The past, like the future, is indefinite and exists only as a spectrum of possibilities.

I think the human race doesn't have a future if it doesn't go into space.

If we want to travel into the future, we just need to go fast. Really fast. And I think the only way we're ever likely to do that is by going into space.

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

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.

I entered the health care debate in response to a statement in the United States press in summer 2009 which claimed the National Health Service in Great Britain would have killed me off, were I a British citizen. I felt compelled to make a statement to explain the error.

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

I had not expected 'A Brief History of Time' to be a best seller. It was my first popular book and aroused a great deal of interest. Initially, many people found it difficult to understand. I therefore decided to try to write a new version that would be easier to follow.

My first popular book, 'A Brief History of Time,' aroused a great deal of interest, but many found it difficult to understand.

I had not expected 'A Brief History of Time' to be a best seller.