Closed strings and the level matching rule

String Theory (Fall, 2010)

October 11, 2010


This lecture starts with a review of Noether’s theorem, which links continuous symmetries with conserved quantities (charges).   The model of a closed string is developed following the earlier procedure for open strings.   The energy spectrum is similar but with a new constraint called the level matching rule linking the energy of waves in each direction around the string that is connected to Noether’s theorem.

  • Why is charge quantized?
  • Noether’s theorem and conserved charges
  • A model of closed strings
  • The energy spectrum of closed strings
  • The level matching rule