The Elegant Universe homepage

A Sense of Scale
The strings of string theory are unimaginably small. And when we say "unimaginably," we mean it: Your average string, if it exists, is about 10^-33 centimeters long. That's a point followed by 32 zeros and then a 1. It's a millionth of a billionth of a billionth of a billionth of a centimeter. (Physicists stick to metric.) Or think of it this way: if an atom were magnified to the size of the solar system, a string would be the size of a tree. Yup, real small.

In this feature, we try to give you a vague sense—for that is all that's possible—of just how small a string is. Starting at an everyday scale, we travel by powers of 100 down into the shadowy world of strings. That is, we begin 10 meters away from an apple, then zoom 100 times closer to 10 centimeters away from its skin, then 100 times closer again to one millimeter from its skin, and so on, down no fewer than 15 additional powers of 100 until we reach the Planck length. Since the Planck length is roughly 17 orders of magnitude smaller than what physicists can currently detect using their largest particle accelerators (in fact, to see individual strings we would need an accelerator the size of the Milky Way), we have taken a kind of visual poetic licence in imagining what the world looks like smaller than a quark. We hope you enjoy this journey into the infinitesimally itsy-bitsy.
—Peter Tyson