All the normal matter in the Milky Way disc is denser than the dark matter that surrounds it.

When it comes to the world around us, is there any choice but to explore?

We should figure out how to do this so that some parents don't feel disenfranchised, angry and upset. It says a lot about the state of where we are in the city, the role of parents and the reality of small school and combining schools.

Speculation and the exploration of ideas beyond what we know with certainty are what lead to progress.

There are many aspects of time we just do not understand. That’s the thing about writing a popular book: You realize the things you understand because for those you can give a really simple explanation. But some things about time I just don’t know how to give simple explanations for, even though I can tell you mathematically what’s going on.

Science is a combination of theory and experiment and the two together are how you make progress.

You have to be careful when you use beauty as a guide. There are many theories people didn't think were beautiful at the time but did find beautiful later—and vice versa. I think simplicity is a good guide: The more economical a theory, the better.