A common way to compute density is, of course, to take the ratio of an object's mass to its volume. But other types of densities exist, such as the resistance of somebody's brain to the imparting of common sense.

The most accessible field in science, from the point of view of language, is astrophysics. What do you call spots on the sun? Sunspots. Regions of space you fall into and you don’t come out of? Black holes. Big red stars? Red giants. So I take my fellow scientists to task. He’ll use his word, and if I understand it, I’ll say, “Oh, does that mean da-da-da-de-da?

Eventually, the Sun will swell to occupy the entire sky as its expansion subsumes the orbit of earth. Earth's surface temperature will rise until it matches the 3,000-degree rarified outer layers of the expanded Sun.... But not to worry. We will surely go extinct for some other reason long before this scenario unfolds.

We live in a world where not everyone has the urge to help others... It is OK to encourage others to pull themselves up by the bootstraps, but if you do, just remember that some people have no boots.

When you innovate, the jobs can't go overseas because other countries haven't figured out how to do it yet.

You could do math early, but there are no brilliant 16-year-old novelists. They don't know the human condition yet.

I want people to see that the cosmic perspective is simultaneously honest about the universe we live in and uplifting, when we realize how far we have come and how wonderful is this world of ours.