In order to achieve a true understanding of string theory, some new idea will be required, and most likely, some break with the concepts on which we've traditionally based physical theory.

The Big Bang theory is the idea that if we go back early enough in the history of the universe - and we can do this, of course, by looking at starlight coming to us from billions of years ago - we will see a very hot and dense period where the universe was much smaller, denser, and hotter.

Some wonder whether some day we will arrive at a theory of everything and run out of new problems to solve - much as the effort to explore the earth ran out of new continents to explore.

Quantum field theory was originally developed for the treatment of electrodynamics, immediately after the completion of quantum mechanics and the discovery of the Dirac equation.

I don't know - it's a bit of a mystery of how things come about when they do. I don't have a scientific explanation for it. Sometimes when you're writing a song, you don't know where you're going.

In 1960, I enrolled in the chemical engineering program at UNAM, as this was then the closest way to become a physical chemist, taking math-oriented courses not available to chemistry majors.

A feeling for history is almost an essential for writing and appreciating good science fiction, for sensing the connections between the past and future that run through our present.

It's hardly a secret that I'm skeptical of declarations that the aliens are out and about on our planet. Still, I try to answer every one of these mails and phone calls because, after all, it's not a violation of physics to travel from one star system to another.