Quantum Foam, Gravitational Thermodynamics, and the Dark Sector

TL;DR

This paper links quantum spacetime fluctuations to the holographic principle, leading to a dynamic cosmological constant and a new dark matter model that fits galactic and cluster data, suggesting non-local quantum properties of dark sector quanta.

Contribution

It introduces a phenomenological 'modified dark matter' model derived from quantum gravitational considerations and tests it against astronomical observations.

Findings

The MDM model fits galaxy rotation curves with a single free parameter.

The model's mass estimates agree with observations in galaxy clusters.

A connection between dark energy, dark matter, and quantum non-locality is proposed.

Abstract

We use two simple independent gedankan experiments to show that the holographic principle can be understood intuitively as having its origin in the quantum fluctuations of spacetime. Applied to cosmology, this consideration leads to a dynamical cosmological constant of the observed magnitude, a result that can also be obtained for the present and recent cosmic eras by using unimodular gravity and causal set theory. Next we generalize the concept of gravitational thermodynamics to a spacetime with positive cosmological constant (like ours) to reveal the natural emergence, in galactic dynamics, of a critical acceleration parameter related to the cosmological constant. We are then led to construct a phenomenological model of dark matter which we call "modified dark matter" (MDM) in which the dark matter density profile depends on both the cosmological constant and ordinary matter. We provide observational tests of MDM by fitting the rotation curves to a sample of 30 local spiral galaxies with a single free parameter and by showing that the dynamical and observed masses agree in a sample of 93 galactic clusters. We also give a brief discussion of the possibility that quanta of both dark energy and dark matter are non-local, obeying quantum Boltzmann statistics (also called infinite statistics) as described by a curious average of the bosonic and fermionic algebras. If such a scenario is correct, we can expect some novel particle phenomenology involving dark matter interactions. This may explain why so far no dark matter detection experiments have been able to claim convincingly to have detected dark matter.