The Fate of Nucleated Black Holes in de Sitter Quantum Gravity
Abstract
The Euclidean Nariai geometry has long been proposed as the instanton describing the nucleation of maximal-mass black holes in de Sitter space. We place this interpretation on firmer footing by showing that, once an observer is included, the gravitational path integral produces the imaginary phase required for a transition rate. As a warmup, we revisit the Hawking-Moss instanton and, as a byproduct, find that scalar fields can enhance black-hole nucleation, suggesting a quantum-gravity bound on scalar potentials with de Sitter solutions. We then study the subsequent semiclassical evolution of the nucleated black hole. We show that the previously claimed "anti-evaporation" channel is unphysical, arising from a quantum state with singular horizons. In a smooth state, the black hole instead undergoes standard thermal Hawking evaporation. We verify explicit agreement with the no-boundary state and argue that this evaporation is not subject to large quantum-gravity corrections. The nucleated black hole thus evaporates completely back to the maximally-entropic empty de Sitter vacuum, making the full process a Boltzmann fluctuation.
Versions
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BibTeX
@misc{shi2026fate,
title = {{The Fate of Nucleated Black Holes in de Sitter Quantum Gravity}},
author = {Xiaoyi Shi and Gustavo J. Turiaci and Chih-Hung Wu},
howpublished = {arXiv},
year = {2026},
month = aug,
doi = {10.48550/arxiv.2605.03015},
eprint = {2605.03015},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2605.03015},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - The Fate of Nucleated Black Holes in de Sitter Quantum Gravity
AU - Xiaoyi Shi
AU - Gustavo J. Turiaci
AU - Chih-Hung Wu
PY - 2026
DA - 2026/08/31
PB - arXiv
DO - 10.48550/arxiv.2605.03015
UR - https://arxiv.org/abs/2605.03015
AB - The Euclidean Nariai geometry has long been proposed as the instanton describing the nucleation of maximal-mass black holes in de Sitter space. We place this interpretation on firmer footing by showing that, once an observer is included, the gravitational path integral produces the imaginary phase required for a transition rate. As a warmup, we revisit the Hawking-Moss instanton and, as a byproduct, find that scalar fields can enhance black-hole nucleation, suggesting a quantum-gravity bound on scalar potentials with de Sitter solutions. We then study the subsequent semiclassical evolution of the nucleated black hole. We show that the previously claimed "anti-evaporation" channel is unphysical, arising from a quantum state with singular horizons. In a smooth state, the black hole instead undergoes standard thermal Hawking evaporation. We verify explicit agreement with the no-boundary state and argue that this evaporation is not subject to large quantum-gravity corrections. The nucleated black hole thus evaporates completely back to the maximally-entropic empty de Sitter vacuum, making the full process a Boltzmann fluctuation.
ER -