Special Physics Seminar

Part of the 40th Anniversary Reunion of the 1967 Honours Physics Class

M-Theory:
A “Theory of Everything” Confronts the Real World

Burt Ovrut

Department of Physics and Astronomy
University of Pennsylvania

A description of the “standard model” of particle physics, with an emphasis on its symmetry groups, will be given. The notion of symmetry will then be generalized to supersymmetry, that is, symmetry between quantum states of different spin. The five supersymmetric strings theories will be introduced. It will be shown how any one of these is potentially a “theory of everything”. The five superstring theories will then be unified into a single theory: M-theory. A discussion of how our world and the standard model of particle physics emerges from M-theory will be given. In the process, the notion of a “brane” will be introduced. The last part of the lecture will focus on a new theory of early universe cosmology, called “Ekpyrotic” cosmology, which arises naturally in M-theory as the cataclysmic collision of two branes. It will be shown how the hot Big Bang can arise in such a collision and how the observed fluctuation spectrum in the cosmic microwave background (CMB) is accurately predicted.