NOVA | Elegant Universe | A Sense of Scale | PBS: "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. "