Holographic Cosmology 3.0

We present a new version of holographic cosmology, which is compatible with present observations. A primordial $p=\rho$ phase of the universe is followed by a brief matter dominated era and a brief period of inflation, whose termination heats the universe. The flatness and horizon problems are solved by the $p=\rho$ dynamics. The model is characterized by two parameters, which should be calculable in a more fundamental approach to the theory. For a large range in the phenomenologically allowed parameter space, the observed fluctuations in the cosmic microwave background were generated during the $p=\rho$ era, and are exactly scale invariant. The scale invariant spectrum cuts off sharply at both upper and lower ends, and this may have observational consequences. We argue that the amplitude of fluctuations is small but cannot yet calculate it precisely.Comment: 22 pages, 3 figures, based on talks presented by the authors at the Nobel Symposium, Sigtuna Stiftelsen, Sweden, June 14 -19, 2003 and at the Conference on String Theory and Cosmology, KITP, UCSB, Santa Barbara, CA, October 20-24, 200