Lecture 11 Jan

Download the lecture notes here:

• 11jan2008

Synopsis

The foci of today’s lecture were as follows:

• unification – why is marrying gravity with gauge forces hard?
• particle worldlines versus string worldsheets;
• handwaving description of the quantum Casimir effect on string oscillations;
• preview of mass formulae and critical dimension for open and closed strings;
• reminder about classical non-relativistic point-particle theory;
• reminder about classical relativistic point-particle theory and the Geometric action;
• the classical Einbein action, and how it handles the mass-shell constraint even for massless particles;
• Hamiltonian physics: from Poisson brackets to quantum commutators.

A Look Ahead

Next time, we’ll introduce the classical action for strings, first for the non-relativistic case and then for the relativistic case. We’ll discuss the construction and symmetries of the Nambu-Goto action.  This will set us up to look at the equations of motion, and especially the boundary conditions, in the following lecture.