String Theory and Cosmology

 

 

 

Shamit Kachru

Stanford University and SLAC

 

 

 

It appears that string theory can give rise to many different 4d worlds, manifesting different values of fundamental parameters such as the cosmological constant.  We discuss the structure of this `landscape' of string vacua, and show that some aspects are amenable to calculation.  We also describe simple models of inflation, dark energy, and particle physics that have been proposed in this context.