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

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

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.

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.

No one can deny the excitement of visiting another world.

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