A central lesson of science is that to understand complex issues (or even simple ones), we must try to free our minds of dogma and to guarantee the freedom to publish, to contradict, and to experiment. Arguments from authority are unacceptable.

Any civilization that doesn't develop space travel dies.

What an astonishing thing a book is. It’s a flat object made from a tree with flexible parts on which are imprinted lots of funny dark squiggles. But one glance at it and you’re inside the mind of another person, maybe somebody dead for thousands of years. ... Books break the shackles of time. A book is proof that humans are capable of working magic.

One of the reasons for its success is that science has a built-in, error-correcting machinery at its very heart. Some may consider this an overbroad characterization, but to me every time we exercise self-criticism, every time we test our ideas against the outside world, we are doing science. When we are self-indulgent and uncritical, when we confuse hopes and facts, we slide into pseudoscience and superstition.

I would be very ashamed of my civilization if we did not try to find out if there is life in outer space.

We on Earth have just awakened to the great oceans of space and time from which we have emerged.

Imagination will often carry us to worlds that never were. But without it we go nowhere.