Detectable universes inside regular black holes

TL;DR

This paper proposes a new class of regular black hole solutions with interior dark energy universes, stabilized by tangential pressure, and suggests they could be detected via gravitational waves in specific frequency ranges.

Contribution

It introduces a spectrum of stable, regular cosmological black hole solutions with interior dark energy universes and links their properties to observable gravitational wave signals.

Findings

Derived a degenerate spectrum of solutions with the same mass-energy and entropy.

Connected classical fluid entropy to Bekenstein-Hawking entropy.

Predicted gravitational wave signatures within the μHz–Hz range detectable by LISA.

Abstract

While spacetime in the vicinity outside astrophysical black holes is believed to be well understood, the event horizon and the interior remain elusive. Here, we discover a degenerate infinite spectrum of novel general relativity solutions with the same mass-energy and entropy that describe a dark energy universe inside an astrophysical black hole. This regular cosmological black hole is stabilized by a finite tangential pressure applied on the dual cosmological-black hole event horizon, localized up to a quantum indeterminacy. We recover the Bekenstein-Hawking entropy formula from the classical fluid entropy, calculated at a Tolman temperature equal to the cosmological horizon temperature. We further calculate its gravitational quasi-normal modes. We find that cosmological black holes are detectable by gravitational-wave experiments operating within the $\mu{\rm Hz}-{\rm Hz}$ range, like LISA space-interferometer.