In the far, far future, essentially all matter will have returned to energy. But because of the enormous expansion of space, this energy will be spread so thinly that it will hardly ever convert back to even the lightest particles of matter. Instead, a faint mist of light will fall for eternity through an ever colder and quieter cosmos.

When I give this talk to a physics audience, I remove the quotes from my 'Theorem'.

Oftentimes, if you're talking to a seasoned interviewer who asks you a question, they may do a follow-up if they didn't quite get it. It's rare that they'll do a third or fourth or fifth or sixth follow-up, because there's an implicit, agreed-upon decorum that they move on. Kids don't necessarily move on if they don't get it.

Free will is the sensation of making a choice. The sensation is real, but the choice seems illusory. Laws of physics determine the future.

Science is a way of life. Science is a perspective. Science is the process that takes us from confusion to understanding in a manner that's precise, predictive and reliable - a transformation, for those lucky enough to experience it, that is empowering and emotional.

When general relativity was first put forward in 1915, the math was very unfamiliar to most physicists. Now we teach general relativity to advanced high school students.

Energy is the ultimate convertable currency.