[On Richard P. Feynman's live demonstration of the rigidity of the O-rings when cold that doomed the space shuttle Challenger, killing seven astronauts:] The public saw with their own eyes how science is done, how a great scientist thinks with his hands, how nature gives a clear answer when a scientist asks her a clear question.

Science was blamed for all the horrors of World War I, just as it's blamed today for nuclear weapons and quite rightly. I mean World War I was a horrible war and it was mostly the fault of science, so that was in a way a very bad time for science, but on the other hand we were winning all these Nobel Prizes.

The whole point of science is that most of it is uncertain. That's why science is exciting--because we don't know. Science is all about things we don't understand. The public, of course, imagines science is just a set of facts. But it's not. Science is a process of exploring, which is always partial. We explore, and we find out things that we understand. We find out things we thought we understood were wrong. That's how it makes progress.

It's clear the media, of course, always gives you the bad news. And people who rely on the media, like Mr. Trump, think that everything is a disaster. The media always tries to make everything into a disaster, but it's mostly rubbish. It's a point of fact that we're doing extremely well.

Every orchid or rose or lizard or snake is the work of a dedicated and skilled breeder. There are thousands of people, amateurs and professionals, who devote their lives to this business. Now imagine what will happen when the tools of genetic engineering become accessible to these people.

A good scientist is a person with original ideas. A good engineer is a person who makes a design that works with as few original ideas as possible. There are no prima donnas in engineering.

I think it's a big mistake to decide too soon what you're going to do with your life.