Until we get rid of religion, we won't be able to conduct the search for God.

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]

Once you can reproduce a phenomenon, you are well on the way to understanding it.

A well-stocked mind is safe from boredom.

If man can live in Manhattan, he can live anywhere.

You will find men like him in all of the world's religions. They know that we represent reason and science, and, however confident they may be in their beliefs, they fear that we will overthrow their gods. Not necessarily through any deliberate act, but in a subtler fashion. Science can destroy a religion by ignoring it as well as by disproving its tenets. No one ever demonstrated, so far as I am aware, the nonexistance of Zeus or Thor, but they have few followers now.

The fact that we have not yet found the slightest evidence for life - much less intelligence - beyond this Earth does not surprise or disappoint me in the least. Our technology must still be laughably primitive, we may be like jungle savages listening for the throbbing of tom-toms while the ether around them carries more words per second than they could utter in a lifetime.