In some sense, gravity does not exist; what moves the planets and the stars is the distortion of space and time.

Science is the engine of prosperity. All the prosperity we see around us is a byproduct of scientific inventions. And that's not being made clear to young people. If we can't make it clear to young people they're not going to go into science. And science will suffer in the United States.

We can summarize electricity, magnetism and gravity into equations one inch long, and that's the power of field theory. And so I said to myself: I will create a field theory of strings. And when I did it one day, it was incredible, realizing that on a sheet of paper I can write down an equation which summarized almost all physical knowledge.

What differentiates human from lower-animal consciousness is time. You can't explain the concept of "tomorrow" to your dog. Our consciousness is dominated by time - We're constantly running simulations of the future. Our brain is a prediction machine. The hallmark of intelligence, indeed of genius, is the number and complexity of the feedback loops we use in predicting the future.

Beyond work and love, I would add two other ingredients that give meaning to life. First, to fulfill whatever talents we are born with. However blessed we are by fate with different abilities and strengths, we should try to develop them to the fullest, rather than allow them to atrophy and decay. ... Second, we should try to leave the world a better place than when we entered it.

Impossible is relative.

If you could meet your grandkids as elderly citizens in the year 2100 … you would view them as being, basically, Greek gods… that's where we're headed.