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Richard Easther Columbia University Brandenberger and Vafa's proposal that the dynamics of strings in the early universe can naturally produce three large spatial dimensions is one of the oldest - and most interesting - ideas in string cosmology. However, Brandenberger and Vafa's proposal is based on a universe with a toroidal geometry, which is now know to be phenomologically unrealistic. In this seminar I describe our first step toward extending this mechanism to D-dimensional toroidal orbifolds. Naively, these spaces have no incontractible loops - a crucial ingredient of the Brandenberger-Vafa hypothesis. However, numerical simulations show that `pseudo-wound' strings can persist for many Hubble times in some of these spaces. The pseudo-wound strings may thus affect the dynamics in the same way as genuinely wound strings, showing that the Brandenberger-Vafa can produce a three dimensional universe from a much more general class of spacetimes than previously suspected.
Monday, May 13th 2002, 13:15 |