Black holes are very exotic objects. Technically, a black hole puts a huge amount of mass inside of zero volume. So our understanding of the center of black holes doesn't make sense, which is a big clue to physicists that we don't have our physics quite right.

Astronomers are obsessed with building larger and larger telescopes. There are two promises that we make with bigger telescopes: that they can see fainter things and that they see more detail. But it's been really hard to follow through on that second promise because of atmospheric distortion.

We have this interesting problem with black holes. What is a black hole? It is a region of space where you have mass that's confined to zero volume, which means that the density is infinitely large, which means we have no way of describing, really, what a black hole is!

The key to proving that there's a black hole is showing that there's a tremendous amount of mass in a very small volume. And you can do that with the motions of stars. The way the star moves around the center of the galaxy is very much like the way the planets orbit the sun.

With the observable fact that scientific knowledge makes our lives better when applied with concern for human welfare and environmental protection, there is no question that science and technology can produce abundance so that no one has to go without.

The scientific spirit is of more value than its products, and irrationally held truths may be more harmful than reasoned errors.

Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve.

People think of science as rolling back the mystery of God. I look at science as slowly creeping toward the mystery of God.