A microscopic black hole on the order of the Planck length cannot accrete ordinary matter at a meaningful rate.
Assessment
The claim traces to reliable primary sources through a clear chain of evidence.
A black hole whose horizon is on the order of the Planck length, roughly 1.6 × 10⁻³⁵ metres, presents a capture cross-section of about the Planck area, some 10⁻⁷⁰ square metres. That is around fifty orders of magnitude smaller than the cross-section of an atomic nucleus, so such an object passing through ordinary matter would almost never encounter anything to swallow, and the time needed for it to accrete any appreciable mass exceeds the age of the universe by an enormous margin. This follows from well-tested gravitational physics and is not disputed by any party to the debates in which the claim arises.
The claim is a standard premise in analyses of the safety of particle colliders, notably CERN's LHC safety assessment and the peer-reviewed study by Giddings and Mangano (Physical Review D, 2008), which modelled accretion by hypothetical stable microscopic black holes from first principles. One point of scope deserves note: the genuine controversy in that literature concerned hypothetical black holes in theories with extra spatial dimensions, whose effective gravitational size can be vastly larger than the four-dimensional Planck length and whose accretion can therefore be faster. Those scenarios fall outside this claim's stated condition. The claim establishes that a truly Planck-sized hole accretes negligibly; it does not by itself settle whether collider-produced black holes would be of that character.
Full reasoning — evidence and decisions behind this verdict
Evidence considered. (1) Both source instances affirm the claim: CERN's "The safety of the LHC" page states that a stable microscopic black hole on the order of the Planck length would be far too small to accrete ordinary matter at any meaningful rate, and Giddings and Mangano (arXiv:0806.3381, published as Phys. Rev. D 78, 035009) state that a black hole trapped inside the Earth would accrete matter only very slowly because of its tiny size. No instance denies it. (2) The underlying physics is elementary and uncontested: the capture cross-section of a Planck-length-scale hole is of order the Planck area (~10⁻⁷⁰ m²), compared with nuclear cross-sections of order 10⁻²⁸ m²; even with gravitational focusing for slow-moving matter, the accretion timescale for such an object embedded in terrestrial-density matter exceeds cosmological timescales by tens of orders of magnitude. Giddings and Mangano derive this from basic, well-tested physical laws.
Adversarial check. I searched for credible dissent. The known critiques of LHC black-hole safety (notably Plaga, arXiv:0808.1415, arguing that metastable quantum black holes could accrete at the Eddington limit and radiate harmfully) concern TeV-scale-gravity scenarios in which the hole's effective gravitational radius is far larger than the four-dimensional Planck length; Giddings and Mangano themselves found that in some low-dimensionality warped scenarios accretion could in principle be faster, which is why they invoked white-dwarf and neutron-star survival bounds. None of this disputes the accretion rate of a hole that is actually of Planck-length size, which is the condition this claim states. Plaga's scenario was also rebutted on consistency grounds (Giddings and Mangano, arXiv:0808.4087). I therefore found no informed party who disputes the claim as stated.
Weighing. The claim traces to a peer-reviewed primary analysis and to first-principles physics, with both instances affirming and no credible contrary evidence: VERIFIED. Credence 0.97 rather than higher only because "meaningful rate" is mildly vague and exotic possibilities (for example long-lived charged relics with enhanced electromagnetic capture) are conceivable, though Giddings and Mangano argue such holes would rapidly neutralize and in any case still face the same minuscule absorption cross-section.
Structure. The claim is left atomic: its support is uncontested cross-section arithmetic, and decomposing settled derivations would violate the contestedness stop rule. The genuinely contested neighboring questions (whether risk analyses are complete, whether astrophysical bounds exclude metastable holes) already exist as separate claims in the graph and bear on the broader LHC-risk claim rather than on this one.
Decomposition
This claim is atomic — it bottoms out in a bedrock fact, a contested empirical question, or a value premise, and does not decompose further.
Provenance
Where this claim has been said, linked to its canonical form.
A stable microscopic black hole would be far too small — on the order of the Planck length — to accrete ordinary matter at any meaningful rate.
Even on the extremely conservative assumption that some microscopic black holes turned out to be stable, they would still pose no danger.
A black hole produced in an LHC collision and trapped inside the Earth would accrete matter only very slowly, because of its tiny size.
Discussion of whether a stable trapped black hole could grow large enough within the Sun's remaining lifetime.
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Created by extractor · Jul 17, 2026. Every judgment on this page is accompanied by a reasoning trace.