String Cosmology: the Pre-Big Bang Scenario

January 5 - January 9 2001

Institut Henri Poincare

Gabriele Veneziano (CERN/ORSAY)

The content of the IHP Lecture notes 50 can be found in

STRING COSMOLOGY: THE PRE BIG BANG SCENARIO by G. Veneziano

hep-th/0002094

Part 1 MOTIVATIONS

• Problems with a beginning of time: conventional inflation
• String-theoretic motivations for the PBB scenario
  • Short-distance motivations
  • Large distance motivations
• Asymptotic past triviality

Part 2 INFLATION AS GRAVITATIONAL COLLAPSE

• General Considerations
• Special cases:
  • Spherical symmetry
  • Planar symmetry
  • p-forms, BKL oscillations
• Fine-tuning issues

Part 3 THE EXIT PROBLEM IN PBB COSMOLOGY

• Necessary conditions for exit
• Partial exit via $\alpha$' corrections
• Loop corrections and toy models of complete exit

Part 4 ENTROPY BOUNDS

• Bekenstein bound and its extensions to cosmology
• General covariant bounds
• CFT tests of entropy bounds.
• Applications
  • String-black hole correspondence
  • Exit problem

Part 5 OBSERVABLE PRE-BANGIAN RELICS ?

• General approach to cosmological perturbations
• Gravitational waves
• Scalar perturbations
• Gauge perturbations and galactic magnetic fields
• Axions and CMB anisotropies

Part 6 SUMMARY AND OUTLOOK