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
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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
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
- 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.
The abstract, sentence by sentence
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
| # | sentence | role | the authors' own work | states the main conclusion | strength |
|---|---|---|---|---|---|
| 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 was examined, and what was not
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Figures
Figures reproduced from arXiv:gr-qc/9606052 by the authors.
References
How later papers used it
75 later papers cite it
4 later papers by other authors are listed below: 3 used its method or tool and 1 compared its own results with it.
Uses its method or tool 3 of 4 papers with this label
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Following Bousso and Hawking [ref] , we fix the normalization using the unique static geodesic observer at $r_O$, defined by $f'(r_O)=0$.
The Fate of Nucleated Black Holes in de Sitter Quantum Gravity (2026) · The near-Nariai throat and two-dimensional dilaton gravity · 0.92
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Followed the gravitational instanton approach proposed by another work and by this paper to estimate the PBH nuclear rate.
Primordial black holes in a dimensionally reduced universe (2018) · 1.00 · paraphrased: the licence does not allow quoting
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Used the normalization proposed by this paper so that the norm of the Killing vector is one where gravitational attraction and cosmological repulsion cancel.
Some aspects of entropic gravity in the presence of a noncommutative Schwarzschild-deSitter black hole (2013) · 0.95 · paraphrased: the licence does not allow quoting
Compares with it 1 of 8 papers with this label
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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
Papers citing it · 89 sentences without a confident label
Contests it 1 paper
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To be clear, we agree with all the equations in the Appendix of [ref] , except for the final result (A.18) for the action.
On the Euclidean Action of de Sitter Black Holes and Constrained Instantons · Near-Nariai expansion · contest 0.81
Builds on it 3 papers
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In previous work [ref] we provided a general and covariant derivation of the Euclidean on-shell action for neutral, nonrotating black holes in de Sitter space, generalizing classic results for the Nariai instanton [ref] , and showed it is equal to minus the sum of the two horizon entropies for arbitrary mass and in any number of dimensions (as was previously done for four dimensions in [ref] ).
Action, entropy and pair creation rate of charged black holes in de Sitter space · Introduction · 0.84
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This process is a generalization of the pair creation of black holes described in Refs. [ref] , when a $CP^1$ field is turned on.
Semiclassical decay of de Sitter space into black holes with vortex-deformed horizons · The decay rate · 1.00
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Our result generalizes a previous computation [ref] of the probability of nucleating a Nariai black hole to arbitrary SdS black holes [ref] in general dimensions.
On the Euclidean Action of de Sitter Black Holes and Constrained Instantons · Conclusion · 0.99
Uses its method or tool 4 papers
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In order to estimate the PBH nuclear rate, we follow the gravitational instanton approach proposed by Mann & Ross [ref] and Bousso & Hawking [ref] .
Primordial black holes in a dimensionally reduced universe · Introduction · 1.00
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Following Bousso and Hawking [ref] , we fix the normalization using the unique static geodesic observer at $r_O$, defined by $f'(r_O)=0$.
The Fate of Nucleated Black Holes in de Sitter Quantum Gravity · The near-Nariai throat and two-dimensional dilaton gravity · 0.92
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In order to prevent a complication in taking the normalization of Killing vector, we use the normalization proposed by Bousso and Hawing [ref] so that the norm of the Killing vector is one at the area where the gravitational attraction and the cosmological repulsion cancel each other and thus the force vanishes.
Some aspects of entropic gravity in the presence of a noncommutative Schwarzschild-deSitter black hole · Verlinde's Entropic Formalism · 0.95
Compares with it 7 papers
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This is precisely what [ref] found for the extremal case.
Festina Lente: EFT Constraints from Charged Black Hole Evaporation in de Sitter · Quasistatic · 0.94
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The process we have described resembles the cosmological pair production of four-dimensional Schwarzschild-de Sitter black holes in the Nariai limit (where the black hole and cosmological horizons coincide) [ref] .
Holography For a De Sitter-Esque Geometry · Instantons · 0.99
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For $d=4$ we recover the result by Bousso and Hawking [ref] , cf. their Eq. (A.16), $κ̃_b,c = √( Λ) (1 ±2/3ϵ̃_0 + 11/18 ϵ̃_0^2 ) + 𝒪(ϵ̃_0^3)$ (see also [ref] ).
On the Euclidean Action of de Sitter Black Holes and Constrained Instantons · SdS geometry and its non-equilibrium thermodynamics · 0.99
Cites it as support 1 paper
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Producing them during inflation is unlikely [ref] .
Comments on magnetic black holes · Production in the early universe? · 0.98
Cites it as background 15 papers
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In this regard, it is well known that dS space is semi-classically unstable to the thermal nucleation of black holes [ref] .
Semiclassical decay of de Sitter space into black holes with vortex-deformed horizons · Introduction · 0.94
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The nucleation process was studied by Bousso and Hawking in the context of primordial black holes (PBHs) created during inflation [ref] .
The Fate of Nucleated Black Holes in de Sitter Quantum Gravity · Introduction · 0.94
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A special role in this paper is played by the Nariai limit [ref] of the wavefunction of a $S^1×S^2$ universe.
The wavefunction of a quantum $S^1 \times S^2$ universe · The Nariai limit of the $S^1 ×S^2$ wavefunction · 0.92
Discussion
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