......Start, Guth says, by imagining nothing, a pure vacuum. Be careful. Don't imagine outer space without matter in it. Imagine no space at all and no matter at all. Good luck.

To the average person it might seem obvious that nothing can happen in nothing. But to a quantum physicist, nothing is, in fact, something. Quantum theory holds that probability, not absolutes, rules any physical system. It is impossible, even in principle, to predict the behavior of any single atom; all physicists can do is predict the average properties of a large collection of atoms. Quantum theory also holds that a vacuum, like atoms, is subject to quantum uncertainties. This means that things can materialize out of the vacuum, although they tend to vanish back into it quickly. While this phenomenon has never been observed directly, measurements of the electron's magnetic strength strongly imply that it is real and happening in the vacuum of space even now.

Theoretically, anything—a dog, a house, a planet—can pop into existence by means of this quantum quirk, which physicists call a vacuum fluctuation. Probability, however, dictates that pairs of subatomic particles—one positive, one negative, so that conservation laws are not violated—are by far the most likely creations and that they will last extremely briefly, typically for only 10-21 second. The spontaneous, persistent creation of something even as large as a molecule is profoundly unlikely.