In less than a hundred years, we have found a new way to think of ourselves. From sitting at the center of the universe, we now find ourselves orbiting an average-sized sun, which is just one of millions of stars in our own Milky Way galaxy.
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 was never top of the class at school, but my classmates must have seen potential in me, because my nickname was 'Einstein.'
Even if it turns out that time travel is impossible, it is important that we understand why it is impossible.
I think we have a good chance of surviving long enough to colonize the solar system.
I can't disguise myself with a wig and dark glasses - the wheelchair gives me away.
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.
I have wondered about time all my life.
Stem cell research is the key to developing cures for degenerative conditions like Parkinson's and motor neuron disease from which I and many others suffer. The fact that the cells may come from embryos is not an objection, because the embryos are going to die anyway.
'The Simpsons' appearances were great fun. But I don't take them too seriously. I think 'The Simpsons' have treated my disability responsibly.
Imaginary time is a new dimension, at right angles to ordinary, real time.
In my school, the brightest boys did math and physics, the less bright did physics and chemistry, and the least bright did biology. I wanted to do math and physics, but my father made me do chemistry because he thought there would be no jobs for mathematicians.
Science is increasingly answering questions that used to be the province of religion.
God not only plays dice, but also sometimes throws them where they cannot be seen.
In my opinion, there is no aspect of reality beyond the reach of the human mind.
Only black holes of very low mass would emit a significant amount of radiation.
Time can behave like another direction in space under extreme conditions.
Some forms of motor neuron disease are genetically linked, but I have no indication that my kind is. No other member of my family has had it. But I would be in favour of abortion if there was a high risk.
We live in a bewildering world.
What I'd really like to control is not machines, but people.
There's no way to remove the observer - us - from our perceptions of the world.
The universe is not indifferent to our existence - it depends on it.
We must develop as quickly as possible technologies that make possible a direct connection between brain and computer, so that artificial brains contribute to human intelligence rather than opposing it.
God not only plays dice, He also sometimes throws the dice where they cannot be seen.
Our minds work in real time, which begins at the Big Bang and will end, if there is a Big Crunch - which seems unlikely, now, from the latest data showing accelerating expansion. Consciousness would come to an end at a singularity.
It now appears that the way the universe began can indeed be determined, using imaginary time.
Theoretical physics is one of the few fields in which being disabled is no handicap - it is all in the mind.
Earth might one day soon resemble the planet Venus.
I can't say that my disability has helped my work, but it has allowed me to concentrate on research without having to lecture or sit on boring committees.
I grew up thinking that a research scientist was a natural thing to be.
My wife and I love each other very much.
The voice I use is a very old hardware speech synthesizer made in 1986. I keep it because I have not heard a voice I like better and because I have identified with it.
The human race may be the only intelligent beings in the galaxy.
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.
When we understand string theory, we will know how the universe began. It won't have much effect on how we live, but it is important to understand where we come from and what we can expect to find as we explore.
There could be shadow galaxies, shadow stars, and even shadow people.
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.
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.
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.
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.