Pith. Sign in

REVIEW

Pair Creation of Black Holes During Inflation

General Relativity and Quantum Cosmology · Submitted 18 Jun 1996 · 23 references

Pith's verdict: The no-boundary derivation and the First Law check are solid and citable; the charged-black-hole exponent in Sec. 6 does not follow from the paper's own equations.

T0 · AI review

How this review was made: An AI referee (selfhosted/deepseek-v4.1-flash) read the paper on November 11, 2026 and answered a fixed list of questions about it. T0 is the starting level every paper gets. The levels describe how deeply Pith has checked the paper, never the authors.

  1. T0 AI review An AI read the paper and answered a fixed list of questions.
  2. T1 Audit Automatic checks that the references and files the paper relies on exist and match.
  3. T2 Compute The paper's code or calculations re-run with the same results.
  4. T3 Formal statement The claims written out in a formal math language a computer can read.
  5. T4 Proof Those claims proved, and the proof checked by computer.

How Pith checks papers →

· 4 major objections · 7 minor · Ask about this paper · The compiled record · Read the full review →
Challenge this review Comment (0) Read on arXiv ↗
Cite ▾
arXiv IDgr-qc/9606052 (version 2)
Pith ID6SYWTJRR, Pith's permanent record of this paper and its review
CitationCambridge), Raphael Bousso, Stephen W. Hawking (DAMTP. "Pair Creation of Black Holes During Inflation." arXiv:gr-qc/9606052 (1996). https://pith.science/paper/6SYWTJRR
Cite this reviewBibTeX for Pith's review of this paper
Claim paper

Why Pith says this

Highlight any text to comment on it.

Referee report
The paper

The paper claims

The same expansion that drove inflation could have pulled pairs of black holes out of the vacuum, and the no-boundary wave function says how often.

The reading

Inflation is driven by a large effective cosmological constant, and this paper asks whether that same expansion can pull a pair of black holes out of the vacuum the way an electric field pulls apart an electron-positron pair. Working within the no-boundary proposal, the authors compare the probability of the ordinary de Sitter instanton, a four-sphere, with that of the $S^2$ x $S^2$ Nariai instanton that carries a black hole pair, and read off a creation rate $Gamma = exp(-pi/Lambda_{eff})$. The rate approaches one only when the effective cosmological constant is near the Planck value, so Planck-mass black holes are produced freely in the earliest stages of inflation while larger ones are exponentially rare. The authors then follow the pairs through inflation: classically they grow in step with the horizon, and that growth is accounted for exactly by the flux of inflaton energy across the horizon through the first law of black hole mechanics, while quantum mechanically most of them evaporate before inflation ends. Finally, magnetically charged black holes cannot evaporate, but the same instanton calculation puts their number in the presently observable universe at roughly $exp(-10^5)$.

What carries the argument

The machinery is the pair of saddle-point instantons and the ratio of their probability measures. The background is half of a round four-sphere of radius $sqrt{3/Lambda}$, continued onto a Lorentzian de Sitter hyperboloid, with real action $-3pi/(2Lambda)$. The black hole pair is carried by the Nariai solution, the topological product $S^2$ x $S^2$ with both two-spheres of radius $1/sqrt{Lambda}$, whose real action is $-pi/Lambda$. The load-bearing technical point is that regularity of the Euclidean section forces the two horizons to have equal radius, so the instanton approach fixes the mass of the created pair rather than leaving it free; the black holes are born degenerate, at the maximum Schwarzschild-de Sitter size. Dividing the two measures gives $Gamma = exp(-pi/Lambda_{eff})$, and doubling the real parts of the actions recovers the conventional $I_{obj} - I_{bg}$ formula.

Extended reading notes

Core claim

The central claim is that the no-boundary wave function, applied to the two competing gravitational instantons, yields a pair creation rate for black holes on an inflationary background that agrees with the standard instanton prescription $Gamma = exp[-(I_{obj} - I_{bg})]$ and behaves sensibly: unsuppressed near the Planck scale, exponentially suppressed at low energies. The rate comes out as $exp(-pi/Lambda_{eff})$, the ratio of the $S^2$ x $S^2$ probability measure $exp(2pi/Lambda)$ to the de Sitter measure $exp(3pi/Lambda)$. The authors argue that the rival tunnelling proposal, which flips the sign of the exponent, would give the reciprocal rate, make de Sitter space catastrophically unstable to black hole formation, and favour larger black holes over smaller ones at low energy, so it cannot be maintained. Two further results ride on the same machinery: the classical growth of the pair during slow roll is shown to satisfy the first law of black hole mechanics with the surface gravity of the degenerate Schwarzschild-de Sitter solution, and the extension to Reissner-Nordstrom-de Sitter instantons gives an exponentially small abundance for magnetically charged primordial black holes in ordinary Einstein-Maxwell theory.

Load-bearing premise

The claim that most neutral black holes evaporate before inflation ends depends on assuming the initial mismatch between the two horizon radii is spread uniformly from zero up to a few Planck lengths, a distribution the authors explicitly say is beyond the scope of the paper and lies where the semi-classical approximation breaks down anyway.

Editorial extensions

If this is right

  • Black hole pair creation during inflation is a real, computable effect whose rate is fixed by the effective cosmological constant at the moment of nucleation, so the primordial black hole mass spectrum is tied directly to the inflationary trajectory.
  • The tunnelling proposal is excluded on physical grounds, since it would make de Sitter space violently unstable to black hole formation and would preferentially create the largest black holes at the lowest energies.
  • Neutral black holes created during inflation grow with the cosmological horizon, and this growth is not an independent assumption but a consequence of energy flux across the horizon obeying the first law of black hole mechanics.
  • Almost all neutral primordial black holes evaporate before inflation ends, so they leave no relics; only pairs born late and large, or born extremely close to degenerate, survive.
  • Magnetically charged primordial black holes survive to the present but are so rare in Einstein-Maxwell theory, roughly $exp[-(9pi^2/(16 alpha m^2))^{1/3}]$, that the observable universe should contain none.

Reading between the lines

Editorial extensions of the paper, not claims the author makes directly.

  • Because the creation rate depends on $Lambda_{eff}$ at nucleation, the resulting black hole abundance is a probe of the inflaton potential at energies far above what the microwave background constrains, so a detection or a firm null result would constrain the shape of $V(phi)$ rather than just its slope.
  • The same probability-ratio argument applies to any instanton whose Euclidean action can be computed, which suggests a general recipe: any topology-changing fluctuation of the inflationary vacuum is suppressed by the difference of real Euclidean actions, and the no-boundary versus tunnelling sign question can be settled case by case.
  • The dilaton remark at the end points to a concrete programme: if the effective fine structure constant or Newton constant was larger in the early universe, the exponent suppressing magnetic black holes shrinks, and the resulting abundance could become a constraint on dilatonic couplings rather than a null prediction.
  • The evaporation conclusion rests on an assumed flat distribution of initial horizon splittings at the Planck scale, so a first-principles calculation of that distribution from the same path integral would either rescue a population of surviving Planck-mass relics or close the question.
Original abstract

Black holes came into existence together with the universe through the quantum process of pair creation in the inflationary era. We present the instantons responsible for this process and calculate the pair creation rate from the no boundary proposal for the wave function of the universe. We find that this proposal leads to physically sensible results, which fit in with other descriptions of pair creation, while the tunnelling proposal makes unphysical predictions. We then describe how the pair created black holes evolve during inflation. In the classical solution, they grow with the horizon scale during the slow roll-down of the inflaton field; this is shown to correspond to the flux of field energy across the horizon according to the First Law of black hole mechanics. When quantum effects are taken into account, however, it is found that most black holes evaporate before the end of inflation. Finally, we consider the pair creation of magnetically charged black holes, which cannot evaporate. In standard Einstein-Maxwell theory we find that their number in the presently observable universe is exponentially small. We speculate how this conclusion may change if dilatonic theories are applied.

The compiled record

The paper's own sentences, arranged, kept beside the review and separate from it. Each label is drawn from a closed vocabulary; the number beside it is the probability the classifier gave that label. Numbers in the tables are the authors', checked by code. No sentence in this record was written by a model.

Compiled by classifier-1.13-20260917 via OpenRouter, question bank abstract-p1-20260923, 2026-09-23: 1 request, 6,777 input tokens, $0.0003 reported.

What the abstract itself states, as probabilities: claims first 0.03 · states limitation 0.61 · human participants 0.01 · controlled comparison 0.12 · randomized assignment 0.01 · states quantitative result 0.45 · compares with prior results 0.89 · mentions code or data availability 0.02.

The abstract, sentence by sentence

arXiv listing abstract v2. Results and the main claim are underlined; .

Black holes came into existence together with the universe through the quantum process of pair creation in the inflationary era. We present the instantons responsible for this process and calculate the pair creation rate from the no boundary proposal for the wave function of the universe. We find that this proposal leads to physically sensible results, which fit in with other descriptions of pair creation, while the tunnelling proposal makes unphysical predictions. We then describe how the pair created black holes evolve during inflation. In the classical solution, they grow with the horizon scale during the slow roll-down of the inflaton field; this is shown to correspond to the flux of field energy across the horizon according to the First Law of black hole mechanics. When quantum effects are taken into account, however, it is found that most black holes evaporate before the end of inflation. Finally, we consider the pair creation of magnetically charged black holes, which cannot evaporate. In standard Einstein-Maxwell theory we find that their number in the presently observable universe is exponentially small. We speculate how this conclusion may change if dilatonic theories are applied.

background contribution method result interpretation main claim

What the classifier reports for each sentence. The number is the probability it gave the label.
#sentencerolethe authors' own workstates the main conclusionstrength
s0 Black holes came into existence together with the universe through the quantum process of pair creation in the inflationary era. background 0.63 0.17 0.48 asserted 1.00
s1 We present the instantons responsible for this process and calculate the pair creation rate from the no boundary proposal for the wave function of the universe. contribution 0.58 0.95 0.07 asserted 0.98
s2 We find that this proposal leads to physically sensible results, which fit in with other descriptions of pair creation, while the tunnelling proposal makes unphysical predictions. result 0.78 0.95 0.26 asserted 1.00
s3 We then describe how the pair created black holes evolve during inflation. contribution 0.97 0.85 0.04 asserted 0.69
s4 In the classical solution, they grow with the horizon scale during the slow roll-down of the inflaton field; this is shown to correspond to the flux of field energy across the horizon according to the First Law of black hole mechanics. result 0.87 0.85 0.07 asserted 1.00
s5 When quantum effects are taken into account, however, it is found that most black holes evaporate before the end of inflation. result 1.00 0.94 0.22 asserted 1.00
s6 Finally, we consider the pair creation of magnetically charged black holes, which cannot evaporate. contribution 0.98 0.56 0.04 asserted 0.58
s7 In standard Einstein-Maxwell theory we find that their number in the presently observable universe is exponentially small. result 1.00 0.93 0.19 asserted 1.00
s8 We speculate how this conclusion may change if dilatonic theories are applied. future work 0.88 0.18 0.04 speculative 1.00

What kind of paper the classifier reports this is: theoretical result 1.00 · evidence from proof or derivation 1.00.

What was examined, and what was not

sources read
  • arXiv listing abstract v2
not examined
  • full text
  • figures and tables
  • references and citing sentences
  • relations to other papers
levels run
  • P abstract
not run
  • S sections
  • T body sentences
  • C citations
  • R cross-paper relations

Every quoted sentence on this record is the authors'. Every label is from Pith's closed vocabulary, with the probability shown beside it. Every number in the measurements table is the authors', checked by code. Record as JSON

Figures
Figure 1. The creation of a de Sitter universe. The lower region is half of a Euclidean
Figure 2. The hypersurfaces in the parameter space of the Reissner{Nordstrom{
Figure 3. The action of the di erent types of Reissner{Nordstrom{de Sitter instan

Figures reproduced from arXiv:gr-qc/9606052 by the authors.

References
How later papers used it

75 later papers cite it

Evidence: substantial. 74 of the citing papers share no author with it, and 14 of those carry a confident label from Pith's citation classifier.

Pith read 21 of the 143 citing sentences, choosing only those whose citation markers point at this paper alone, and wrote the paraphrases from them. The summary, the counts, the evidence level, the links and the quotes come from code; the summary counts the papers listed below. A later paper is listed under a label when Pith's citation classifier gives one of its sentences that label at probability 0.8 or more (0.95 for support), Pith's reading finds that the citing paper itself did it, and a second check confirms the paraphrase against the sentence. This section lists uses only. It does not list criticism or disagreement, so their absence here says nothing about how the paper has been received. Papers that share an author with this one are listed apart, under "By the same authors". A quote is the citing authors' own sentence, shown when their paper's licence is CC BY, CC BY-SA or CC0. JSON

Uses its method or tool 3 of 4 papers with this label
Compares with it 1 of 8 papers with this label
  • Said that the process it described resembles this paper's cosmological pair production of four-dimensional Schwarzschild-de Sitter black holes in the Nariai limit.

    Holography For a De Sitter-Esque Geometry (2011) · 0.99 · paraphrased: the licence does not allow quoting

How the literature uses it

61 arXiv papers cite this in 126 sentences

Each citing sentence is taken from the citing paper's LaTeX source and typed by Pith's classifier. A label appears at probability 0.8 or more (0.95 for support), a contest at 0.7 or more; the quoted words are the citing authors'. How each label was checked · JSON

Papers citing it · 89 sentences without a confident label

Contests it 1 paper
Builds on it 3 papers
Uses its method or tool 4 papers
Compares with it 7 papers
Cites it as support 1 paper
Cites it as background 15 papers

Discussion

Disagree with the review, or know something it missed? Leave a comment, highlight any passage above to comment on it, or challenge this review formally.