The technologies which have had the most profound effects on human life are usually simple. A good example of a simple technology with profound historical consequences is hay. Nobody knows who invented hay, the idea of cutting grass in the autumn and storing it in large enough quantities to keep horses and cows alive through the winter. All we know is that the technology of hay was unknown to the Roman Empire but was known to every village of medieval Europe. Like many other crucially important technologies, hay emerged anonymously during the so-called Dark Ages.

Everything in my life was luck.

The biggest breakthrough in the next 50 years will be the discovery of extraterrestrial life. We have been searching for it for 50 years and found nothing. That proves life is rarer than we hoped, but does not prove that the universe is lifeless. We are only now developing the tools to make our searches efficient and far-reaching, as optical and radio detection and data processing move forward.

The brain, being analog, is able to grasp images so much better. The brain is just designed for comparing images and some patterns - patterns in space and patterns in time - which we do amazingly well. Computers can do it, too, but not in anything like the same kind of flexibility.

We do not know how much of the environmental change is due to human activities and how much [is due] to long-term natural processes over which we have no control.

Most of what we see in the universe is dust.

It is not surprising that honest and well-informed experts can disagree about facts. But beyond the disagreement about facts, there is another deeper disagreement about values.