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

"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."

"I regard the afterlife to be a fairy story for people that are 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."

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

"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."

"In the Universe it may be that Primitive life is very common and intelligent life is fairly rare. Some would say it has yet to occur on Earth."

"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."

"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 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."

"Remember to 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. And however difficult life may seem, there is always something you can do and succeed at. It matters that you don't just give up."

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

"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."

"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."

"I'm never any good in the morning. It is only after four in the afternoon that I get going."

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

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

"The message of this lecture is that black holes ain't as black as they are painted. They are not the eternal prisons they were once though things can get out of a black hole both on the outside and possibly to another universe. So if you feel you are in a black hole, don't give up " there's a way out."

"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."

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

"Life would be tragic if it weren't funny."

"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."

"I like physics, but I love cartoons."

"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."

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

"However bad life may seem, where there is life, there is hope."

"T is generally recognized that women are better than men at languages, personal relations and multitasking, 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 not politically correct to say such things....But it cannot be denied that there are differences between men and women. Of course, these are differences between the averages only. There are wide variations about the mean."

"Why are we here?where do we come from?traditionally,these are questionsfor philosophy,but philosophy is dead."

"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."

"Perhaps one day I will go into space."

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

"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."

"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."

"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."

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

"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?"

"I believe the simplest explanation is, there is no God. No one created the universe and no one directs our fate. This leads me to a profound realization that there probably is no heaven and no afterlife either. We have this one life to appreciate the grand design of the universe and for that, I am extremely grateful."

"There should be no boundaries to human endeavor. (...) However bad life may seem (...) While there's life, there is 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.'"

"Among physicists, I'm respected I hope."

"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."

"Today will still yearn to know why we are here and where we came from. Humanity's deepest desire for knowledge is justification enough for our continuing quest. And our goal is nothing less than a complete description of the universe we live in."

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

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

"A scientific theory is just a mathematical model we make to describe our observations: it exists only in our minds. So it is meaningless to ask: which is real, "real" or "imaginary" time? It is simply a matter of which is the more useful description."

"Only in the few universes that are like ours would intelligent beings develop and ask the question: "Why is the universe the way we see it? The answer is then simple: If it had been any different, we would not be here!"

"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."

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

"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."