There are no wild, seedless watermelons. There's no wild cows... You list all the fruit, and all the vegetables, and ask yourself, is there a wild counterpart to this? If there is, it's not as large, it's not as sweet, it's not as juicy, and it has way more seeds in it. We have systematically genetically modified all the foods, the vegetables and animals that we have eaten ever since we cultivated them. It's called artificial selection.

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.

I have thoughts every day that are themselves tweets.

I try to show the public that chemistry, biology, physics, astrophysics is life. It is not some separate subject that you have to be pulled into a corner to be taught about.

The more I learn about the universe, the less convinced I am that there's any sort of benevolent force that has anything to do with it, at all.

There are as many atoms in each molecule of your DNA as there are stars in the typical galaxy. This is true for dogs, and bears, and every living thing. We are, each of us, a little universe.

I [do not know] when the end of science will come. ... What I do know is that our species is dumber than we normally admit to ourselves. This limit of our mental faculties, and not necessarily of science itself, ensures to me that we have only just begun to figure out the universe.