Stephen Hawking

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.

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.

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.

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.

Intelligence is the ability to adapt to change.

I believe things cannot make themselves impossible.

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

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

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.

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.

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.

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.

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.

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

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

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.

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

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

Life would be tragic if it weren't funny.