Stephen Hawking Quotes

133 Sourced Quotes

As scientists, we understand the dangers of nuclear weapons and their devastating effects, and we are learning how human activities and technologies are affecting climate systems in ways that may forever change life on Earth. As citizens of the world, we have a duty to alert the public to the unnecessary risks that we live with every day, and to the perils we foresee if governments and societies do not take action now to render nuclear weapons obsolete and to prevent further climate change... There's a realization that we are changing our climate for the worse. That would have catastrophic effects. Although the threat is not as dire as that of nuclear weapons right now, in the long term we are looking at a serious threat.

Stephen Hawking
The human race is just a chemical scum on a moderate-sized planet, orbiting around a very average star in the outer suburb of one among a hundred billion galaxies. We are so insignificant that I can't believe the whole universe exists for our benefit. That would be like saying that you would disappear if I closed my eyes.

Stephen Hawking
The development of full artificial intelligence could spell the end of the human race. We cannot quite know what will happen if a machine exceeds our own intelligence, so we can't know if we'll be infinitely helped by it, or ignored by it and sidelined, or conceivably destroyed by it.

Stephen Hawking
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.

Stephen Hawking
A million million million million (1 with twenty-four zeros after it) miles, the size of the observable universe.

Stephen Hawking
We are each free to believe what we want and it is my view that 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. 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.

Stephen Hawking
My expectations were reduced to zero when I was 21. Everything since then has been a bonus.

Stephen Hawking
The zero-G part was wonderful and the higher-G part was no problem. I could have gone on and on. Space, here I come!

Stephen Hawking
If there is one thing we can be sure enough of in physics it is that all time exists with equal reality.

Stephen Hawking
You would have to fly around the world four hundred million times to add one second to your life; but your life would be reduced by more than that by all those airline meals.

Stephen Hawking
Cosmology used to be considered a pseudoscience and the preserve of physicists who might have done some useful work in their earlier years but who had gone mystic in their dotage.

Stephen Hawking
Three minutes' thought would suffice to find this out; but thought is irksome and three minutes is a long time.

Stephen Hawking
The stars and galaxies that fill our view as we survey the depths of the Universe are really just a froth delineating the massive, dark unseen structures beneath.

Stephen Hawking
There's nothing like the Eureka moment, of discovering something that no one knew before.

Stephen Hawking
But if he [God] had started it [the universe] off in such an incomprehensible way, why did he choose to let it evolve according to laws that we could understand?

Stephen Hawking
Time is like a river flowing endlessly through the universe.

Stephen Hawking
Science fiction like Star Trek is not only good fun but it also serves a serious purpose, that of expanding the human imagination.

Stephen Hawking
There may be ultimate answers, but if there are, I would be sorry if we were to find them. For my own sake I would like very much to find them, but their discovery would leave nothing for those coming after me to seek. Each generation builds on the advances of the previous generation, and this is as it should be. As human beings, we need the quest.

Stephen Hawking
The laws of science, as we know them at present, contain many fundamental numbers, like the size of the electric charge of the electron and the ratio of the masses of the proton and the electron.... The remarkable fact is that the values of these numbers seem to have been finely adjusted to make possible the development of life.

Stephen Hawking
At present, computers are a useful aid in research, but they have to be directed by human minds. If one extrapolates their recent rapid rate of development, however, it would seem quite possible that they will take over altogether in theoretical physics. So maybe the end is in sight for theoretical physicists, if not for theoretical physics.

Stephen Hawking
Gravity is so strong that space is bent round onto itself, making it rather like the surface of the earth. If one keeps traveling in a certain direction on the surface of the earth, one never comes up against an impassable barrier or falls over the edge, but eventually comes back to where one started.

Stephen Hawking
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.

Stephen Hawking
I have sold more books on physics than Madonna has on sex.
[Hawking adopted this statement from a remark made to him by his former post-doc, Nathan Myhrvold.]

Stephen Hawking
The theory of relativity does, however, force us to change fundamentally our ideas of space and time. We must accept that time is not completely separate from and independent of space, but is combined with it to form an object called space-time.

Stephen Hawking
It is impossible to imagine a four-dimensional space. I personally find it hard enough to visualize a three-dimensional space!

Stephen Hawking
The point is that the new raw material doesn't really have to come from anywhere.... The universe can start off with zero energy and still create matter.

Stephen Hawking
Time refuses to be simplified or reduced. You cannot say that it is only found in the mind or only in the universe, that it runs only in one direction, or in everyone imaginable. That it exists only in biological substructure, or is only a social convention. It is all of these things.

Stephen Hawking
But a machine that was powerful enough to accelerate particles to the grand unification energy would have to be as big as the Solar System - and would be unlikely to be funded in the present economic climate.

Stephen Hawking
I think the universe is completely self-contained. It doesn't have any beginning or end, it doesn't have any creation or destruction.

Stephen Hawking
There could be whole antiworlds and antipeople made out of antiparticles. However, if you ever meet your antiself, don't shake hands! You would both vanish in a great flash of light.

Stephen Hawking