During my time in orbit, I lost bone mass, my muscles atrophied, and my blood redistributed itself in my body, which strained my heart. Every day, I was exposed to ten times the radiation of a person on Earth, which will increase my risk of a fatal cancer for the rest of my life.

I always think of space-time as being the real substance of space, and the galaxies and the stars just like the foam on the ocean.

Science is feasible when the variables are few and can be enumerated; when their combinations are distinct and clear. We are tending toward the condition of science and aspiring to do it. The artist works out his own formulas; the interest of science lies in the art of making science.

As a theoretician, I am proud to be part of a counter revolution... discovering that quantum field theory language was not dead and finished but had not really been explored thoroughly enough.

The Soyuz craft weighs tons, and you're lying on the floor of it on your back. But the Russians do tell you, remember, before you land, stop talking so you don't bite your tongue off.

When asked ... [about] an underlying quantum world, Bohr would answer, 'There is no quantum world. There is only an abstract quantum physical description. It is wrong to think that the task of physics is to find out how nature is. Physics concerns what we can say about Nature.'