The PhD system is the real root of the evil of academic snobbery. People who have PhDs consider themselves a priesthood, and inventors generally don't have PhDs.

Successful technologies often begin as hobbies. Jacques Cousteau invented scuba diving because he enjoyed exploring caves. The Wright brothers invented flying as a relief from the monotony of their normal business of selling and repairing bicycles.

Just because you see pictures of glaciers falling into the ocean doesn't mean anything bad is happening. This is something that happens all the time. It's part of the natural cycle of things. We know from measurements that glaciers have been melting for 200 years at least.

[John Wheeler] rejuvenated general relativity; he made it an experimental subject and took it away from the mathematicians

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.

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.

We must be careful not to discourage our twelve-year-olds by making them waste the best years of their lives preparing for examinations.