An Holographic Cosmology

TL;DR

The paper proposes a holographic cosmology in which the early universe is a dense black hole fluid with $p=\rho$, naturally solving the horizon problem and producing Gaussian, scale-invariant fluctuations within a causality-limited range. It sketches a two-phase cosmic evolution ending in a radiation-dominated era and discusses intriguing predictions such as relic magnetically charged black monopoles and a low reheat temperature, offering an alternative to inflation grounded in holographic principles. While the framework robustly addresses several foundational cosmological issues, it predicts a restricted range for scale-invariant perturbations, prompting questions about alignment with observations and the need for possible refinements to the fluctuation treatment. Overall, the work highlights a coherent, Planck- and M-theory–informed scenario that reframes early-universe problems through holographic entropy bounds and UV/IR correspondence, providing new avenues for connecting quantum gravity to cosmology.

Abstract

We present a new cosmological model, based on the holographic principle, which shares many of the virtues of inflation. The very earliest semiclassical era of the universe is dominated by a dense gas of black holes, with equation of state $p=ρ$. Fluctuations lead to an instability to a phase with a dilute gas of black holes, which later decays via Hawking radiation to a radiation dominated universe. The quantum fluctuations of the initial state give rise to a scale invariant spectrum of density perturbations, for a range of scales. We point out a problem, that appears to prevent the range of scales predicted by the model from coinciding with the range where such a spectrum has been observed. We speculate that this may be related to our field theoretic treatment of fluctuations in the highly holographic $p=ρ$ background. The monopole problem is solved in a manner completely different from inflationary models, and a relic density of highly charged extremal black monopoles is predicted. We discuss the nature of the entropy and flatness problems in our model.