The Invisible Tension of the Universe from Astrophysical Black Holes: a Solution to the Coincidence Problem of the Accelerated Expansion

TL;DR

This paper proposes that black holes generate a gravitational aether, which manifests as the universe's small but non-zero accelerated expansion tension, potentially solving the coincidence problem without anthropic reasoning.

Contribution

It introduces a novel hypothesis linking black holes to the universe's accelerated expansion through quantum gravity effects, addressing the coincidence problem.

Findings

Black holes may produce a gravitational aether.

This aether could explain the universe's small acceleration tension.

The model offers a natural explanation for the timing of cosmic acceleration.

Abstract

Astronomical observations have shown that the expansion of the universe is at present accelerating, consistently with a constant negative pressure or tension. This is a major puzzle because we do not understand why this tension is so small compared to the Planck density; why, being so small, it is not exactly zero; and why it has precisely the required value to make the expansion start accelerating just at the epoch when we are observing the universe. The recently proposed conjecture by Afshordi that black holes create a gravitational aether owing to quantum gravity effects, which may be identified with this invisible tension, can solve this coincidence problem. The fact that the expansion of the universe is starting to accelerate at the epoch when we observe it is a necessity that is implied by our origin in a planet orbiting a star that formed when the age of the universe was of the same order as the lifetime of the star. This argument is unrelated to any anthropic reasoning.