It's clearly possible for a something to acquire higher intelligence than its ancestors: we evolved to be smarter than our ape-like ancestors, and Einstein was smarter than his parents.

I think those who have a terminal illness and are in great pain should have the right to choose to end their own life, and those that help them should be free from prosecution.

My first popular book, 'A Brief History of Time,' aroused a great deal of interest, but many found it difficult to understand.

One might think this means that imaginary numbers are just a mathematical game having nothing to do with the real world. From the viewpoint of positivist philosophy, however, one cannot determine what is real. All one can do is find which mathematical models describe the universe we live in. It turns out that a mathematical model involving imaginary time predicts not only effects we have already observed but also effects we have not been able to measure yet nevertheless believe in for other reasons. So what is real and what is imaginary? Is the distinction just in our minds?

There should be a better way to start a day than waking up every morning.

I don't think the human race will survive the next thousand years, unless we spread into space. There are too many accidents that can befall life on a single planet. But I'm an optimist. We will reach out to the stars.

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