string theory

Basic idea

Replaces point particles with one-dimensional “strings” whose vibrational modes give particle properties. Requires 10 (superstring) or 11 (M-theory) spacetime dimensions.

Key formulas

• Nambu-Goto action: $S = -T \int d^2\sigma\, \sqrt{-\det h_{ab}}$
• Polyakov action: $S = -\dfrac{T}{2}\int d^2\sigma\,\sqrt{-h}\,h^{ab}\partial_a X^\mu \partial_b X_\mu$
• String tension: $T = 1/(2\pi\alpha')$

Pages

• String Theory

Siblings

• loop quantum gravity
• quantum loop gravity
• quantum physics
• relativity