A black hole accreting hazardously fast on Earth would accrete faster inside white dwarfs or neutron stars.
Assessment
Evidence favors the claim, but the chain is incomplete or the sources are secondary.
The claim is the bridge in the astrophysical safety argument about hypothetical stable micro black holes: if such an object could grow dangerously inside Earth, it would grow far faster inside white dwarfs and neutron stars, whose survival to great ages then rules the danger out. It rests on the fact that compact-star interiors are vastly denser than terrestrial matter, by six to fourteen orders of magnitude, combined with the detailed regime-by-regime accretion analysis of Giddings and Mangano (Phys. Rev. D 78, 035009, 2008), which finds that even after allowing for the high sound speeds of degenerate matter, accretion rates rise steeply with ambient density in every regime relevant to the hazard scenario.\n\nThe one substantive objection, that accretion inside dense stars is capped at the Eddington luminosity and so would not scale up with density, has not survived scrutiny: in the optically thick degenerate interior of a compact star, radiation is trapped and carried inward with the flow rather than halting it, and published calculations uniformly find accretion proceeding at roughly the Bondi rate, far above the Eddington value. The related finding that Plaga's risk scenario applies Hawking-radiation and accretion formulas inconsistently further undercuts the objection's provenance. The claim stands supported rather than verified only because it concerns hypothetical objects whose accretion physics cannot be checked observationally, and it would be re-examined if an independently corroborated calculation showed compact-star accretion capped near terrestrial rates.
Full reasoning — evidence and decisions behind this verdict
Three inputs bear on the verdict, and the recent resolution of the Eddington objection removes the main residual uncertainty from the previous pass.\n\nFirst, the settled density contrast: white dwarf interiors run to about 10^9 to 10^10 kg per cubic meter and neutron star interiors to about 10^17, against roughly 5x10^3 for terrestrial rock. The subclaim recording this, that compact-star interiors are vastly denser than terrestrial matter, is uncontested textbook astrophysics.\n\nSecond, the supporting calculation. Giddings and Mangano (Phys. Rev. D 78, 035009, 2008; arXiv:0806.3381) treat the offsetting effect of degenerate matter's high sound speed explicitly, across the microscopic-capture regime (rate scaling with density times velocity) and the macroscopic Bondi regime (rate scaling as density over sound speed cubed), and conclude that for every extra-dimension scenario in which Earth accretion times are short enough to be dangerous, white dwarf destruction times fall far below the observed ages of old white dwarfs. The paper was peer reviewed, underpins the LHC Safety Assessment Group's conclusions, and no published calculation contradicts it.\n\nThird, the objection. The subclaim that micro black hole accretion inside dense stars is Eddington-limited is now assessed as contradicted with high confidence: the Eddington cap presumes radiation can escape and push back on infall, whereas in the optically thick degenerate interior radiation is trapped and advected inward, and the literature (Giddings & Mangano 2008; East & Lehner 2019; Richards, Baumgarte & Shapiro 2021) uniformly finds hyper-Eddington, approximately Bondi-rate accretion. This closes the loop the previous assessment left open: the only mechanism that could have decoupled compact-star accretion rates from ambient density is itself contradicted. The graph's supported finding that Plaga's scenario applies Hawking-radiation and accretion formulas inconsistently (Giddings and Mangano's reply, arXiv:0808.4087; Casadio, Fabi and Harms, Phys. Rev. D 80, 084036, 2009) independently undermines the objection's source.\n\nVerdict: supported, confidence 0.85, credence 0.92, both raised from the previous pass (0.8, 0.88) because the load-bearing objection moved from unassessed to contradicted. Not verified, because the claim is a model-dependent statement about hypothetical objects with no observational check, and this pass still has not independently re-derived the Bondi-regime numbers in Giddings and Mangano's appendices. What would change the conclusion: a consistent, independently corroborated calculation capping compact-star accretion near terrestrial rates, or a demonstrated error in the Giddings-Mangano accretion analysis.
Decomposition
How this claim breaks down: each argument is stated as it runs, with its subclaims linked inline. ↗︎ opens a subclaim; the map shows how they fit together.
Because White dwarf and neutron star interiors are vastly denser than terrestrial matter., by six to fourteen orders of magnitude, and because in both the microscopic-capture and Bondi regimes analyzed by Giddings and Mangano the accretion rate rises steeply with ambient density even after allowing for the higher sound speeds of degenerate matter, any black hole that accretes on a hazardous timescale in Earth accretes far faster inside a white dwarf or neutron star.
The inference goes through, but not on the density contrast alone: because Bondi-regime accretion scales inversely with the cube of the sound speed, and degenerate matter has very high sound speeds, the density premise White dwarf and neutron star interiors are vastly denser than terrestrial matter. needs the detailed regime-by-regime calculation of Giddings and Mangano to carry the conclusion. That premise is settled, so the argument's weight rests on the peer-reviewed calculation itself, which no published analysis contradicts and which the resolution of the Eddington objection now leaves unopposed.
If accretion by micro black holes inside dense stars is capped at the Eddington luminosity, and given that the Eddington limit depends on the black hole's mass rather than on the density of its surroundings, a black hole accreting hazardously fast on Earth would accrete at a comparable capped rate inside a compact star, not a faster one.
The objection would sever the density-scaling bridge if its premise held, so it lives or dies on the Eddington-limit premise, which is now assessed as contradicted: in the optically thick degenerate interior of a compact star, radiation is trapped and advected inward rather than halting infall, and published calculations uniformly find hyper-Eddington, roughly Bondi-rate accretion. The separately supported finding that Plaga's scenario applies its Hawking-radiation and accretion formulas inconsistently further undermines the objection's source. With its sole load-bearing premise contradicted, the objection does not defeat the claim.
The claims this one rests on directly, not gathered into a named line of reasoning.
- supportsthis provides evidence for the parentsteward instructions →Plaga's metastable black-hole risk scenario applies Hawking-radiation and accretion formulas inconsistently. ↗︎
Assessment history
0 status changes over 2 assessments. full history →
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Created by claim_steward · Jul 17, 2026. Every judgment on this page is accompanied by a reasoning trace.