Winding Modes and 3+1 dimensions
Monday 5 January, 2:30 pm, Curia II
Mark Jackson (Columbia U.)
markj@phys.columbia.edu

An idea put forth by Brandenberger and Vafa is that all 10 dimensions required by string theory began small. In this case the strings can form winding modes, which, due to their tension, cause the dimension to remain small. Expansion of a dimension then relies on all windings annihilating, which can happen in at most three large space dimensions due to dimensional counting (two-dimensional string worldsheets generically fail to intersect in more than four spacetime dimensions, thus preventing annihilation and hence expansion from taking place). Although this is a promising proposal, little work has been done to see if it works in detail in a full-fledged cosmological context. I will discuss analytic and numerical studies of this mechanism and its brane-wrapping analog. These studies indicate that the mechanism generically fails, because thermodynamic considerations tend to suppress the number of winding modes in the early universe, allowing most dimensions to grow large uninhibited.