COSMOLOGY Prospects in Theoretical Physics Institute for Advance

COSMOLOGY Prospects in Theoretical Physics Institute for Advance Study July, 2002

• What every string theorist should know about the Universe • Inflationary Cosmology • Cyclic Universe

Salient Features of the Universe • Homogeneity and isotropy • Universe expanding uniformly • thermal background of radiation with T~3 K • chemical composition is roughly 75% H, 25% He, + trace • ordinary matter is more abundant than ordinary antimatter • nearly scale invariant, adiabatic CMB fluctuations • universe is spatially flat • hierarchy of lumpy structure from 1 kpc to 100 Mpc scales • ordinary matter is a minority (1/6 x) of all matter • matter is a minority (1/4 x) of all energy • expansion rate is accelerating

c p M 0 0 2 1 Mpc =3. 3 x 1019 km = 3. 26 x 106 l-yr

13 00 M pc

6000 Mpc

Salient Features of the Universe • Homogeneity and isotropy for 6000 Mpc > x > 100 Mpc • Universe expanding uniformly • thermal background of radiation with T~3 K • chemical composition is roughly 75% H, 25% He, + trace • ordinary matter is more abundant than ordinary antimatter • nearly scale invariant, adiabatic CMB fluctuations • universe is spatially flat • hierarchy of lumpy structure from 1 kpc to 100 Mpc scales • ordinary matter is a minority (1/6 x) of all matter • matter is a minority (1/4 x) of all energy • expansion rate is accelerating

H = 72 ± 3 (stat) ± 7 (sys) km/s/Mpc Hubble Key Project

Consequences • Universe has a finite age ~ 1/H ~ 14 Gyrs • Universe has a horizon Finite age + finite speed of light • Can look back in time red shift (z) time

Salient Features of the Universe • Homogeneity and isotropy for 6000 Mpc > x > 100 Mpc • Universe expanding uniformly • thermal background of radiation with T~3 K • chemical composition is roughly 75% H, 25% He, + trace • ordinary matter is more abundant than ordinary antimatter • nearly scale invariant, adiabatic CMB fluctuations • universe is spatially flat • hierarchy of lumpy structure from 1 kpc to 100 Mpc scales • ordinary matter is a minority (1/6 x) of all matter • matter is a minority (1/4 x) of all energy • expansion rate is accelerating

evidence Universe was once hotter than. 1 e. V

evidence that the Universe was once hotter than 1 Me. V evidence of baryon asymmetry

Salient Features of the Universe • Homogeneity and isotropy for 6000 Mpc > x > 100 Mpc • Universe expanding uniformly • thermal background of radiation with T~3 K • chemical composition is roughly 75% H, 25% He, + trace • ordinary matter is more abundant than ordinary antimatter • nearly scale invariant, adiabatic CMB fluctuations • universe is spatially flat • hierarchy of lumpy structure from 1 kpc to 100 Mpc scales • ordinary matter is a minority (1/6 x) of all matter • matter is a minority (1/4 x) of all energy • expansion rate is accelerating

compare temperature at two points angle apart

temperature fluctuation Large angular scales outside the horizon at last scattering

temperature fluctuation