Real science can be far stranger than science fiction and much more satisfying.

The "Powers That Be" are not smart enough to engineer Armageddon, but they may yet be stupid enough. If governments are involved in covering up the knowledge of aliens, then they are doing a much better job of it than they seem to do at anything else.

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.

The progress of the human race in understanding the universe has established a small corner of order in an increasingly disordered universe.

If time travel is possible, where are the tourists from the future?

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.

One is always a long way from solving a problem until one actually has the answer.