The factor most ignored in discussing interstellar flight is the kinetic energy that must be invested in the ship to make its tons of matter move at a substantial fraction of the speed of light.

Antimatter is not a source of energy for us, it's a method of storing energy, compact but inefficient.

No one can deny the excitement of visiting another world.

Years of science fiction have produced a mindset that it is human destiny to expand from Earth, to the Moon, to Mars, to the stars.

Above all, I would not expect a wise race, at great expense, to set loose an army of self-replicating robots.

It would be a pity if, frustrated by the price of travel, we elected to become a society that never made contact, that never gave SETI a fair chance.

Present annual world energy consumption is about equal to the annihilation energy of 4 tons of matter.

In the past, on Earth, it has largely been to exploit foreign resources and to expand the domestic territory.

People who pride themselves on their "complexity" and deride others for being "simplistic" should realize that the truth is often not very complicated. What gets complex is evading the truth.

A halo surrounded the grim reaper nun, Sister Maria. (By the way-I like this human idea of the grim reaper. I like the scythe. It amuses me.)

Follow your dreams with all of your mind. Chase your dreams with all of your heart. Accomplish your dreams with all of your soul.

All men have a soul.

Christianity is a rebellion against natural law, a protest against nature. Taken to its logical extreme, Christianity would mean the systematic cultivation of the human failure.

I'll be very busy, which is all I need.

Any person who wants to govern the world is by definition the wrong person to do it.

It takes longer for man to find out man than any other creature that is made.

The purpose of painting is to decorate the walls. Therefore it has to be as rich as possible

I lived in Minnesota in a small town.