The Fabric of the Cosmos: Space, Time, and the Texture of Reality

by Brian Greene

By the highest level in the figure, which shows the fabric of space on scales smaller than the Planck length—a millionth of a billionth of a billionth of a billionth (10−33) of a centimeter—space becomes a seething, boiling cauldron of frenzied fluctuations. As the illustration makes clear, the usual notions of left/right, back/forth, and up/down become so jumbled by the ultramicroscopic tumult that they lose all meaning. Even the usual notion of before/after, which we’ve been illustrating by sequential slices in the spacetime loaf, is rendered meaningless by quantum fluctuations on time scales shorter than the Planck time, about a tenth of a millionth of a trillionth of a trillionth of a trillionth (10−43) of a second (which is roughly the time it takes light to travel a Planck length).