The more you learn, the more you know. The more you know, the more you forget. The more you forget, the less you know. So why bother to learn.

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.

Not to leave planet Earth would be like castaways on a desert island not trying to escape...Sending humans to other planets ... will shape the future of the human race in ways we don't yet understand, and may determine whether we have any future at all.

Everyone can enjoy a life of luxurious leisure if the machine-produced wealth is shared, or most people can end up miserably poor if the machine-owners successfully lobby against wealth redistribution.

I don't believe that the ultimate theory will come by steady work along existing lines. We need something new. We can't predict what that will be or when we will find it because if we knew that, we would have found it already!

The development of full artificial intelligence could spell the end of the human race.

Observations indicate that the universe is expanding at an ever-increasing rate. It will expand forever, getting emptier and darker. Although the universe doesn’t have an end, it had a beginning in the Big Bang. One might ask what is before that but the answer is that there is nowhere before the Big Bang just as there is nowhere south of the South Pole.