“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 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.”

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

“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.”

“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?”

“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.”

“God not only plays dice, He also sometimes throws the dice 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.”

“I can't disguise myself with a wig and dark glasses - the wheelchair gives me away.”

“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 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 think the human race will survive the next thousand years, unless we spread into space.”

“I don't want to write an autobiography because I would become public property with no privacy left.”

“I enjoy all forms of music - pop, classical and opera.”

“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 grew up thinking that a research scientist was a natural thing to be.”

“I had a bet with Gordon Kane of Michigan University that the Higgs particle wouldn't be found.”

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

“I have a full and satisfying life. My work and my family are very important to me.”

“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.”

“I have so much that I want to do. I hate wasting time.”

“I have visited Japan several times and have always been shown wonderful hospitality.”

“I have wanted to fly into space for many years, but never imagined it would really be feasible.”

“I have wondered about time all my life.”

“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.”

“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.”

“I think it quite likely that we are the only civilization within several hundred light years; otherwise we would have heard radio waves.”

“I think the brain is essentially a computer and consciousness is like a computer program. It will cease to run when the computer is turned off. Theoretically, it could be re-created on a neural network, but that would be very difficult, as it would require all one's memories.”

“I think the discovery of supersymmetric partners for the known particles would revolutionize our understanding of the universe.”

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

“I think those who have a terminal illness and are in great pain should have the right to choose to end their own life, and those that help them should be free from prosecution.”

“I think we have a good chance of surviving long enough to colonize the solar system.”

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

“I want to know why the universe exists, why there is something greater than nothing.”

“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 was never top of the class at school, but my classmates must have seen potential in me, because my nickname was 'Einstein.'”

“I was not a good student. I did not spend much time at college; I was too busy enjoying myself.”

“I would like nuclear fusion to become a practical power source. It would provide an inexhaustible supply of energy, without pollution or global warming.”

“I wouldn't be here today if it were not for the NHS. I have received a large amount of high-quality treatment without which I would not have survived.”

“If aliens visit us, the outcome would be much as when Columbus landed in America, which didn't turn out well for the Native Americans.”

“If I had to choose a superhero to be, I would pick Superman. He's everything that I'm not.”

“If the rate of expansion one second after the Big Bang had been smaller by even one part in a hundred thousand million million, it would have recollapsed before it reached its present size. On the other hand, if it had been greater by a part in a million, the universe would have expanded too rapidly for stars and planets to form.”

“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.”

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

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

“Imaginary time is a new dimension, at right angles to ordinary, real time.”

“In Britain, like most of the developed world, stem-cell research is regarded as a great opportunity. America will be left behind if it doesn't change policy.”

“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.”

“In my opinion, there is no aspect of reality beyond the reach of the human mind.”

“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.”

“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.”

“Intelligence is the ability to adapt to change.”

“It is extremely important to me to write for children.”

“It is generally recognised that women are better than men at languages, personal relations and multi-tasking, but less good at map-reading and spatial awareness. It is therefore not unreasonable to suppose that women might be less good at mathematics and physics.”

“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.”

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

“It now appears that the way the universe began can indeed be determined, using imaginary time.”

“It was Einstein's dream to discover the grand design of the universe, a single theory that explains everything. However, physicists in Einstein's day hadn't made enough progress in understanding the forces of nature for that to be a realistic goal.”

“It's a pity that nobody has found an exploding black hole. If they had, I would have won a Nobel prize.”

“Keeping an active mind has been vital to my survival, as has been maintaining a sense of humor.”

“Life on Earth is at the ever-increasing risk of being wiped out by a disaster, such as sudden global nuclear war, a genetically engineered virus or other dangers we have not yet thought of.”

“Life would be tragic if it weren't funny.”

“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.”

“Many badly needed goals, like fusion and cancer cure, would be achieved much sooner if we invested more.”

“Many people find the universe confusing - it's not.”

“Maybe I don't have the most common kind of motor neuron disease, which usually kills in two or three years.”

“Most people don't have time to master the very mathematical details of theoretical physics.”

“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.”

“M-theory is the unified theory Einstein was hoping to find.”

“My advice to other disabled people would be, concentrate on things your disability doesn't prevent you doing well, and don't regret the things it interferes with. Don't be disabled in spirit as well as physically.”

“My discovery that black holes emit radiation raised serious problems of consistency with the rest of physics. I have now resolved these problems, but the answer turned out to be not what I expected.”

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

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

“My wife and I love each other very much.”

“My work and my family are very important to me.”

“No one can resist the idea of a crippled genius.”

“No one undertakes research in physics with the intention of winning a prize. It is the joy of discovering something no one knew before.”

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

“Nothing cannot exist forever.”

“Observations indicate that the universe is expanding at an ever increasing rate. It will expand forever, getting emptier and darker.”

“Obviously, because of my disability, I need assistance. But I have always tried to overcome the limitations of my condition and lead as full a life as possible. I have traveled the world, from the Antarctic to zero gravity.”

“One cannot really argue with a mathematical theorem.”

“One can't predict the weather more than a few days in advance.”

“Only black holes of very low mass would emit a significant amount of radiation.”

“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.”

“Our population and our use of the finite resources of planet Earth are growing exponentially, along with our technical ability to change the environment for good or ill.”

“People who boast about their I.Q. are losers.”

“People won't have time for you if you are always angry or complaining.”

“Perhaps one day I will go into space.”

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

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

“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.”

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

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

“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.”

“Scientists have become the bearers of the torch of discovery in our quest for knowledge.”

“So long as the universe had a beginning, we could suppose it had a creator. But if the universe is really completely self-contained, having no boundary or edge, it would have neither beginning nor end: it would simply be. What place, then, for a creator?”

“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.”

“Some scientists think it may be possible to capture a wormhole and enlarge it many trillions of times to make it big enough for a human or even a spaceship to enter.”

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

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

“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.”

“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.”

“The cyclic universe theory predicts no gravitational waves from the early universe.”

“The doctor who diagnosed me with ALS, or motor neuron disease, told me that it would kill me in two or three years.”

“The human race may be the only intelligent beings in the galaxy.”

“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.”

“The missing link in cosmology is the nature of dark matter and dark energy.”

“The Paralympic Games is about transforming our perception of the world.”

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

“The Planck satellite may detect the imprint of the gravitational waves predicted by inflation. This would be quantum gravity written across the sky.”

“The radiation left over from the Big Bang is the same as that in your microwave oven but very much less powerful. It would heat your pizza only to minus 271.3*C - not much good for defrosting the pizza, let alone cooking it.”

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

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

“The universe is not indifferent to our existence - it depends on it.”

“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?”

“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 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.”

“Theology is unnecessary.”

“Theoretical physics is one of the few fields in which being disabled is no handicap - it is all in the mind.”

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

“There are no black holes in the sense of regimes from which light can't escape to infinity.”

“There are too many accidents that can befall life on a single planet.”

“There could be shadow galaxies, shadow stars, and even shadow people.”

“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.”

“There is no physical law precluding particles from being organised in ways that perform even more advanced computations than the arrangements of particles in human brains.”

“There is no unique picture of reality.”

“There's no way to remove the observer - us - from our perceptions of the world.”

“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.”

“Time can behave like another direction in space under extreme conditions.”

“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.”

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

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

“To my mathematical brain, the numbers alone make thinking about aliens perfectly rational. The real challenge is to work out what aliens might actually be like.”

“Using e-mail, I can communicate with scientists all over the world.”

“Wagner manages to convey emotion with music better than anyone, before or since.”

“We are all different. There is no such thing as a standard or run-of-the-mill human being, but we share the same human spirit.”

“We are all now connected by the Internet, like neurons in a giant brain.”

“We are in danger of destroying ourselves by our greed and stupidity. We cannot remain looking inwards at ourselves on a small and increasingly polluted and overcrowded planet.”

“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.”

“We are the product of quantum fluctuations in the very early universe.”

“We live in a bewildering world.”

“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.”

“We only have to look at ourselves to see how intelligent life might develop into something we wouldn't want to meet.”

“We should seek the greatest value of our action.”

“We think we have solved the mystery of creation. Maybe we should patent the universe and charge everyone royalties for their existence.”

“What I'd really like to control is not machines, but people.”

“What was God doing before the divine creation?”

“When one's expectations are reduced to zero, one really appreciates everything one does have.”

“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.”

“While physics and mathematics may tell us how the universe began, they are not much use in predicting human behavior because there are far too many equations to solve. I'm no better than anyone else at understanding what makes people tick, particularly women.”

“Why are we here? Where do we come from? Traditionally, these are questions for philosophy, but philosophy is dead.”

“With genetic engineering, we will be able to increase the complexity of our DNA, and improve the human race. But it will be a slow process, because one will have to wait about 18 years to see the effect of changes to the genetic code.”

“Women. They are a complete mystery.”

“Work gives you meaning and purpose and life is empty without it.”

“You can't regulate every lab in the world.”