If all our common-sense notions about the universe were correct, then science would have solved the secrets of the universe thousands of years ago. The purpose of science is to peel back the layer of the appearance of the objects to reveal their underlying nature. In fact, if appearance and essence were the same thing, there would be no need for science.

To understand the difficulty of predicting the next 100 years, we have to appreciate the difficulty that the people of 1900 had in predicting the world of 2000.

Chances are, the aliens will not want to land on our backyard, or even the White House lawn, with their flying saucers. They may have tiny, robotic self-replicating probes which can reach near light speed and can proliferate around the galaxy. So instead of the Enterprise and huge star ships, the aliens might actually send tiny probes to explore the universe. One might land on our lawn and we won't even know.

I realized very early in life what my abilities and limitations were, and foreign languages was definitely one of my limitations. With strenuous effort, I just barely passed my French class at Harvard so I could graduate.

The human brain has 100 billion neurons, each neuron connected to 10 thousand other neurons. Sitting on your shoulders is the most complicated object in the known universe.

I think a colony in space will take much longer than sci fiction writers think. It costs $10,000 to put a pound of anything into near earth orbit. That is your weight in gold. It costs about $100,000 a pound to put you on the moon. And it costs $1,000,000 a pound to put you on Mars.

I believe we exist in a multiverse of universes.