Stephen Hawking

"I have noticed that even those who assert that everything is predestined and that we can change nothing about it still look both ways before they cross the street."

"When people ask me if a god created the universe, I tell them that the question itself makes no sense. Time didn’t exist before the big bang, so there is no time for god to make the universe in. It’s like asking directions to the edge of the earth; The Earth is a sphere; it doesn’t have an edge; so looking for it is a futile exercise. We are each free to believe what we want, and it’s my view that the simplest explanation is; there is no god. No one created our universe,and no one directs our fate. This leads me to a profound realization; There is probably 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."

"I regard the afterlife to be a fairy story for people that are afraid of the dark"

"The downside of my celebrity is that I cannot go anywhere in the world without being recognized. It is not enough for me to wear dark sunglasses and a wig. The wheelchair gives me away."

"If time travel is possible, where are the tourists from the future?"

"There is a fundamental difference between religion, which is based on authority, and science, which is based on observation and reason. Science will win because it works."

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

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

"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."

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

"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."

"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."

"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."

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

"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."

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