The Hidden Reality: Parallel Universes and the Deep Laws of the Cosmos

by Brian Greene

In fact, the theory encourages us to think of a vibrating string not merely as dictating the properties of its host particle but rather as being the particle. Because of the string’s infinitesimal size, on the order of the Planck length—10–33 centimeters—even today’s most refined experiments cannot resolve the string’s extended structure. The Large Hadron Collider, which slams particles together with energies just beyond 10 trillion times that embodied by a single proton at rest, can probe to scales of about 10–19 centimeters; that’s a millionth of a billionth the width of a strand of hair, but still orders of magnitude too large to resolve phenomena at the Planck length. And so, just as earth would look dotlike if viewed from Pluto, strings would appear dotlike when studied even with the most advanced particle accelerator in the world. Nevertheless, according to string theory, particles are strings.