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

An almost indispensable skill for any creative person is the ability to pose the right questions. Creative people identify promising, exciting, and, most important, accessible routes to progress - and eventually formulate the questions correctly.

You might find it hard to imagine gravity as a weak force, but consider that a small magnet can hold up a paper clip, even though the entire earth is pulling down on it.

I did not set out to explain the extinction of the dinosaurs. I'm a particle physicist, and I was actually thinking about dark matter along with some collaborators.

You can be only a modest distance away from the gravity brane, and gravity will be incredibly weak.

I think it's a problem that people are considered immoral if they're not religious. That's just not true. If you do something for a religious reason, you do it because you'll be rewarded in an afterlife or in this world. That's not quite as good as something you do for purely generous reasons.

There is real confusion about what it means to be right and wrong - the difference between what spiritual beliefs are and what science is.