A hundred years ago, Auguste Compte, ... a great philosopher, said that humans will never be able to visit the stars, that we will never know what stars are made out of, that that's the one thing that science will never ever understand, because they're so far away. And then, just a few years later, scientists took starlight, ran it through a prism, looked at the rainbow coming from the starlight, and said: "Hydrogen!" Just a few years after this very rational, very reasonable, very scientific prediction was made, that we'll never know what stars are made of.

However, one new theory says that dark matter may be ordinary matter in a parallel universe. If a galaxy is hovering above in another dimension, we would not be able to see it. It would be invisible, yet we would feel its gravity. Hence, it might explain dark matter.

Science is definitely part of America's infrastructure, the engine of prosperity. And yet science is given almost no visibility in the media.

We physicists don't like to admit it, but some of us are closet science fiction fans. We hate to admit it because it sounds undignified. But when we were children, that's when we got interested in science, for a lot of us.

After that cancellation [of the Superconducting Super Collider in Texas, after $2 billion had been spent on it], we physicists learned that we have to sing for our supper. ... The Cold War is over. You can't simply say "Russia!" to Congress, and they whip out their checkbook and say, "How much?" We have to tell the people why this atom-smasher is going to benefit their lives.

We are slowly isolating the genes involved with the aging process. We do not have the fountain of youth, but I think, in the coming decades, we will unravel the aging process at the genetic level.

To become a theoretical physicist ... you need to have a passionate love affair with the universe.