When you buy a jacket, you pick the size to ensure it fits. Similarly, we live in a universe in which the amount of dark energy fits our biological make-up. If the amount of dark energy were substantially different from what we've measured, the environmental conditions would be inhospitable to our form of life.

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.

We are living through a remarkably privileged era when certain deep truths about the cosmos are still within reach of the human spirit of exploration.

...things are the way they are in our universe because if they weren't, we wouldn't be here to notice.

Intelligence is the ability to take in information from the world and to find patterns in that information that allow you to organize your perceptions and understand the external world.

Evidence in support of general relativity came quickly. Astronomers had long known that Mercury’s orbital motion around the sun deviated slightly from what Newton’s mathematics predicted. In 1915, Einstein used his new equations to recalculate Mercury’s trajectory and was able to explain the discrepancy, a realization he later described to his colleague Adrian Fokker as so thrilling that for some hours it gave him heart palpitations.

I believe the process of going from confusion to understanding is a precious, even emotional, experience that can be the foundation of self-confidence.