Religion is a byproduct of fear.

The more wonderful the means of communication, the more trivial, tawdry, or depressing its contents seemed to be.

It was one thing to have guessed it, another to have had that guess confirmed beyond possibility of refutation.

Perhaps, as some wit remarked, the best proof that there is Intelligent Life in Outer Space is the fact it hasn't come here. Well, it can't hide forever - one day we will overhear it.

Attempting to define science fiction is an undertaking almost as difficult, though not so popular, as trying to define pornography... In both pornography and SF, the problem lies in knowing exactly where to draw the line.

It was the mark of a barbarian to destroy something one could not understand.

One orbit, with a radius of 42,000 kilometers, has a period of exactly 24 hours. A body in such an orbit, if its plane coincided with that of the Earth's equator, would revolve with the Earth and would thus be stationary above the same spot on the planet. It would remain fixed in the sky of a whole hemisphere ... [to] provide coverage to half the globe, and for a world service three would be required, though more could be readily utilized. (1945) [Predidicting geosynchronous communication satellites]