Physical Society Colloquium
Inflation and the String Theory Landscape
Department of Physics
MIT
After a quick review of how inflation works, I will discuss some of the
key features of our universe that suggest that it emerged from a period of
inflation: its uniformity, its near-critical mass density, and the spectrum of
density perturbations that is now observed in the cosmic microwave background
radiation. I will then turn to the biggest outstanding mystery in cosmology:
the value of the cosmological constant, or equivalently the energy density
of the vacuum. Nobody understands why it is so small. One controversial
explanation starts with the claim that string theory offers a colossal number
of vacuum states, with varying energy densities. If inflation can populate all
of these vacua, and life evolves only in vacua with small energy densities,
then the mystery might be solved. I will argue that this explanation is
logically sound, but I will stop short of claiming that it is right.
Friday, October 26th 2007, 15:30
Ernest Rutherford Physics Building, Keys Auditorium (room 112)
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