Observed Features of the Universe Universe is homogeneous

Observed Features of the Universe • Universe is homogeneous and isotropic on lengths > 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 spectrum of CMB fluctuations • hierarchy of structure from 1 kpc to 1 Mpc scales • universe is spatially flat • ordinary matter is a minority (1/6 x) of all matter • matter is a minority (1/4 x) of all energy • expansion rate accelerating

Why is the Universe homogeneous and isotropic? Robs (t 0) = radius of observable universe today ~ 1/H 0 ~ t 0 Robs (t) = size of same patch at time t

Why is the Universe homogeneous and isotropic? Robs (t 0) = radius of observable universe today ~ 1/H 0 ~ t 0 Robs (t) = size of same patch at time t >> 1 universe decelerating HORIZON PROBLEM

Why is the Universe so FLAT? Recall: >> 1 universe decelerating FLATNESS PROBLEM

Why so few monopoles? if monopoles are stable: MONOPOLE PROBLEM

HORIZON PROBLEM FLATNESS PROBLEM MONOPOLE PROBLEM t

HORIZON PROBLEM FLATNESS PROBLEM MONOPOLE PROBLEM t accelerated expansion

INFLATION inflation = finite period of accelerated expansion

w < -1/3 means KE < V/2 Planck units

INFLATIONARY MENU ENTRANCE phase transition “chaos” stochastic INFLATION Slow roll EXIT scalar field decay flat potentials bubble nucleation power-law potentials de Sitter fluct’s “tunneling from nothing” two or more fields defect driven tensor (R + a R 2 +…) fermi condensate KE driven oscillation extended

Density Perturbations H nearly constant

Density Perturbations inflation ends, H-1 grows

for scalar field, B and E = 0 Newtonian gauge: F = Y

kh >>1:

large x oscillating small x growing nearly scale invariant !

large x oscillating small x growing

More generally … need this to be small w ~ -1: INFLATION w >> 1: EKPYROTIC/CYCLIC

AMPLITUDE Strategies 1) Evolve u -equation 2) famous trick 3) heuristic:

The Cyclic Universe w/Neil Turok with many important contributions from: Justin Khoury (Princeton), Burt Ovrut (Penn) and Nathan Seiberg (IAS)

Consensus (big bang + inflation) big bang

Consensus (big bang + inflation) big bang inflation

Consensus Cyclic (big bang + inflation) PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? ?

Consensus Cyclic (big bang + inflation) PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? ? V Y

Consensus Cyclic (big bang + inflation) PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? ? V “contraction” Y

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” the “bounce” (big bang + inflation)

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” Reproduces successful predictions the “bounce” (big bang + inflation)

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” Fewer ingredients: no need for inflation the “bounce” (big bang + inflation)

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” Dark energy given a purpose the “bounce” (big bang + inflation)

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” Avoids infinities? the “bounce” (big bang + inflation)

Consensus Cyclic PJS & Neil Turok big bang “bang” inflation radiation matter dark energy ? ? “contraction” ? ? ? “crunch” More complete theory of cosmic history the “bounce” (big bang + inflation)

The Cyclic Universe “branes” V Y Y Field-theory M-theory

The Cyclic Universe THE BOUNCE V Y