Cosmologies, singularities and quantum extremal surfaces

Goswami, Kaberi; Narayan, K.; Saini, Hitesh Kumar

doi:10.1007/jhep03(2022)201

Cited by 15 publications

(14 citation statements)

References 62 publications

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“…The reason why it is even possible to apply the derived expressions for the entropy to de Sitter space, is that they are agnostic about the precise background under consideration. While originally studied in the context of holography in Anti-de Sitter space, by now many works have applied this so-called island formula to other backgrounds, such as a plethora of black hole solutions [16][17][18][19][20][21][22][23][24][25] and cosmological spacetimes [14,15,[26][27][28][29][30][31][32][33][34][35][36][37][38][39]. As long as it is possible to unambiguously define a subsystem entangled with a gravitating region, the island formula applies.…”

mentioning

confidence: 99%

The price of curiosity: information recovery in de Sitter space

Aalsma

Sybesma

2021

J. High Energ. Phys.

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Recent works have revealed that quantum extremal islands can contribute to the fine-grained entropy of black hole radiation reproducing the unitary Page curve. In this paper, we use these results to assess if an observer in de Sitter space can decode information hidden behind their cosmological horizon. By computing the fine-grained entropy of the Gibbons-Hawking radiation in a region where gravity is weak we find that this is possible, but the observer’s curiosity comes at a price. At the same time the island appears, which happens much earlier than the Page time, a singularity forms which the observer will eventually hit. We arrive at this conclusion by studying de Sitter space in Jackiw-Teitelboim gravity. We emphasize the role of the observer collecting radiation, breaking the thermal equilibrium studied so far in the literature. By analytically solving for the backreacted geometry we show how an island appears in this out-of-equilibrium state.

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mentioning

confidence: 99%

The price of curiosity: information recovery in de Sitter space

Aalsma

Sybesma

2021

J. High Energ. Phys.

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“…In the present context, one can study the generalized entropy for such I + observers as well (see [71] for some discussions on classical RT/HRT surfaces at I + in SdS, and [103] and earlier work in dS). This reveals quantum extremal surfaces that are timelike-separated from observers at I + : there are parallels with studies in the Poincare patch of de Sitter [85], [101]. In SdS however, one might imagine mapping the radiation region R + to a corresponding interval at the future boundary e.g.…”

Section: Discussionmentioning

confidence: 61%

Small Schwarzschild de Sitter black holes, quantum extremal surfaces and islands

Goswami¹,

Narayan²

2022

Preprint

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We study 4-dimensional Schwarzschild de Sitter black holes in the regime where the black hole mass is small compared with the de Sitter scale. Then the de Sitter temperature is very low compared with that of the black hole and we study the black hole, approximating the ambient de Sitter space as a frozen classical background. We consider distant observers in the static diamond, far from the black hole but within the cosmological horizon. Using 2-dimensional tools, we find that the entanglement entropy of radiation exhibits linear growth in time, indicative of the information paradox for the black hole. Self-consistently including an appropriate island emerging at late times near the black hole horizon leads to a reasonable Page curve. There are close parallels with flat space Schwarzschild black holes in the regime we consider.

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“…the imaginary part arising from log(−1) in the timelike separation in the interval (more generally the real part contains ∆ 2 < 0). This imaginary part has appeared previously in studies of quantum extremal surfaces in de Sitter with regard to the future boundary [22,23].…”

Section: -Dim Cft Timelike Subsystems Complex Eementioning

confidence: 62%

“…Imaginary values also arise in studies of quantum extremal surfaces in de Sitter with regard to the future boundary [22,23], stemming from timelike-separations (sec. 2.3).…”

Section: Introductionmentioning

confidence: 99%

de Sitter space, extremal surfaces and "time-entanglement"

Narayan¹

2022

Preprint

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We refine previous investigations on de Sitter space and extremal surfaces anchored at the future boundary I + . Since such surfaces do not return, they require extra data or boundary conditions in the past (interior). In entirely Lorentzian de Sitter spacetime, this leads to future-past timelike surfaces stretching between I ± . Apart from an overall −i factor (relative to spacelike surfaces in AdS) their areas are real and positive. With a no-boundary type boundary condition, the top half of these timelike surfaces joins with a spacelike part on the hemisphere giving a complex-valued area.Motivated by these, we describe two aspects of "time-entanglement" in simple toy models in quantum mechanics. One is based on a future-past thermofield double type state entangling timelike separated states, which leads to entirely positive structures.Another is based on the time evolution operator and reduced transition amplitudes, which leads to complex-valued entropy.

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Cosmologies, singularities and quantum extremal surfaces

Cited by 15 publications

References 62 publications

The price of curiosity: information recovery in de Sitter space

The price of curiosity: information recovery in de Sitter space

Small Schwarzschild de Sitter black holes, quantum extremal surfaces and islands

de Sitter space, extremal surfaces and "time-entanglement"

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