Speech has allowed the communication of ideas, enabling human beings to work together to build the impossible. Mankind's greatest achievements have come about by talking, and its greatest failures by not talking. It doesn't have to be like this. Our greatest hopes could become reality in the future. With the technology at our disposal, the possibilities are unbounded. All we need to do is make sure we keep talking.

Science is beautiful when it makes simple explanations of phenomena or connections between different observations.

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?

I think [contacting an alien civilization] would be a disaster. The extraterrestrials would probably be far in advance of us. The history of advanced races meeting more primitive people on this planet is not very happy, and they were the same species. I think we should keep our heads low.

It's the gravity that shapes the large scale structure of the universe, even though it is the weakest of four categories of forces

I think the universe was spontaneously created out of nothing, according to the laws of science. It has no beginning and no end.

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