To the scientist, the universality of physical laws makes the cosmos a marvelously simple place. By comparison, human nature-the psychologist's domain-is infinitely more daunting.

This fear factor, this war driver is a very strong one and it's been with the species ever since the beginning and it motivated the Great Wall of China. War can be aggressive or defensive, right? So it motivated the Great Wall of China. Our space program was reactive to Russia.

It is astonishing to realize that until Galileo performed his experiments on the acceleration of gravity in the early seventeenth century, nobody questioned Aristotle's falling balls. Nobody said, Show Me!

Eventually, the Sun will swell to occupy the entire sky as its expansion subsumes the orbit of earth. Earth's surface temperature will rise until it matches the 3,000-degree rarified outer layers of the expanded Sun.... But not to worry. We will surely go extinct for some other reason long before this scenario unfolds.

It could be that these other civilizations, if they are far more advanced intellectually than we are, would not even measure our existence as a blip on the intelligence radar. They could be so advanced that we are to them what worms are to us.

For all we know, the aliens have already done this and unwittingly concluded that there was no intelligent life on Earth. They would now be looking elsewhere. A more humbling possibility would be if aliens had become aware of the technologically proficient species that now inhabits Earth, yet they had drawn the same conclusion.

Whether or not you can become great at something, you can always become better.