Instability of flat spacetime in semiclassical gravity

1982 ◽  
Vol 114 (1) ◽  
pp. 27-30 ◽  
Author(s):  
Hidenaga Yamagishi
Keyword(s):  
Flat Spacetime ◽  
Semiclassical Gravity

scholarly journals Islands and stretched horizon

2021 ◽  
Vol 2021 (7) ◽  
Author(s):  
Yoshinori Matsuo
Keyword(s):  
Black Holes ◽  
Black Hole ◽  
Hawking Radiation ◽  
Entanglement Entropy ◽  
Total System ◽  
Island Rule ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Ads Spacetime ◽  
Hole Geometry

Abstract Recently it was proposed that the entanglement entropy of the Hawking radiation contains the information of a region including the interior of the event horizon, which is called “island.” In studies of the entanglement entropy of the Hawking radiation, the total system in the black hole geometry is separated into the Hawking radiation and black hole. In this paper, we study the entanglement entropy of the black hole in the asymptotically flat Schwarzschild spacetime. Consistency with the island rule for the Hawking radiation implies that the information of the black hole is located in a different region than the island. We found an instability of the island in the calculation of the entanglement entropy of the region outside a surface near the horizon. This implies that the region contains all the information of the total system and the information of the black hole is localized on the surface. Thus the surface would be interpreted as the stretched horizon. This structure also resembles black holes in the AdS spacetime with an auxiliary flat spacetime, where the information of the black hole is localized at the interface between the AdS spacetime and the flat spacetime.

scholarly journals Soft photon theorem in the small negative cosmological constant limit

2021 ◽  
Vol 2021 (8) ◽  
Author(s):  
Nabamita Banerjee ◽  
Karan Fernandes ◽  
Arpita Mitra
Keyword(s):  
Cosmological Constant ◽  
Tree Level ◽  
Leading Order ◽  
Asymptotically Flat ◽  
Soft Factor ◽  
Flat Spacetime ◽  
Electromagnetic Interactions ◽  
Flat Spacetimes ◽  
Perturbative Corrections ◽  
Soft Factors

Abstract We study the effect of electromagnetic interactions on the classical soft theorems on an asymptotically AdS background in 4 spacetime dimensions, in the limit of a small cosmological constant or equivalently a large AdS radius l. This identifies 1/l2 perturbative corrections to the known asymptotically flat spacetime leading and subleading soft factors. Our analysis is only valid to leading order in 1/l2. The leading soft factor can be expected to be universal and holds beyond tree level. This allows us to derive a 1/l2 corrected Ward identity, following the known equivalence between large gauge Ward identities and soft theorems in asymptotically flat spacetimes.

CAUSAL BULK VISCOUS COSMOLOGIES IN CONFORMALLY FLAT SPACETIME

2000 ◽  
Vol 09 (04) ◽  
pp. 475-493 ◽  
Author(s):  
M. K. MAK ◽  
T. HARKO
Keyword(s):  
Large Time ◽  
Viscosity Coefficient ◽  
Approximate Solutions ◽  
Conformally Flat ◽  
First Order ◽  
Flat Spacetime ◽  
Bulk Viscous ◽  
Type Differential Equation ◽  
Bulk Viscosity Coefficient ◽  
Large Time Limit

The evolution of a causal bulk viscous cosmological fluid filled open conformally flat spacetime is considered. By means of appropriate transformations the equation describing the dynamics and evolution of the very early Universe can be reduced to a first order Abel type differential equation. In the case of a bulk viscosity coefficient proportional to the square root of the density, ξ~ρ1/2, an exact and two particular approximate solutions are obtained. The resulting cosmologies start from a singular state and generally have a noninflationary behavior, the deceleration parameter tending, in the large time limit, to zero. The thermodynamic consistency of the results is also checked.

scholarly journals Self-Consistent Wormhole Solutions of Semiclassical Gravity

1997 ◽  
Vol 78 (11) ◽  
pp. 2050-2053 ◽  
Author(s):  
David Hochberg ◽  
Arkadiy Popov ◽  
Sergey V. Sushkov
Keyword(s):  
Semiclassical Gravity ◽  
Self Consistent

Gravity in flat spacetime

2001 ◽  
pp. 195-221
Author(s):  
Milutin Blagojević
Keyword(s):  
Flat Spacetime

scholarly journals BMS flux algebra in celestial holography

2021 ◽  
Vol 2021 (11) ◽  
Author(s):  
Laura Donnay ◽  
Romain Ruzziconi
Keyword(s):  
Solution Space ◽  
Coadjoint Representation ◽  
Energy Tensor ◽  
Stress Energy Tensor ◽  
Asymptotically Flat ◽  
Flat Spacetime ◽  
Stress Energy ◽  
Momentum Fluxes ◽  
Non Local ◽  
Asymptotic Symmetries

Abstract Starting from gravity in asymptotically flat spacetime, the BMS momentum fluxes are constructed. These are non-local expressions of the solution space living on the celestial Riemann surface. They transform in the coadjoint representation of the extended BMS group and correspond to Virasoro primaries under the action of bulk superrotations. The relation between the BMS momentum fluxes and celestial CFT operators is then established: the supermomentum flux is related to the supertranslation operator and the super angular momentum flux is linked to the stress-energy tensor of the celestial CFT. The transformation under the action of asymptotic symmetries and the OPEs of the celestial CFT currents are deduced from the BMS flux algebra.

Do electromagnetic waves harbour gravitational waves?

2006 ◽  
Vol 462 (2071) ◽  
pp. 1987-2000 ◽  
Author(s):  
Brian Bramson
Keyword(s):  
General Relativity ◽  
Gravitational Waves ◽  
Electric Dipole ◽  
Electromagnetic Waves ◽  
Maxwell Theory ◽  
Flat Spacetime

In linearized, Einstein–Maxwell theory on flat spacetime, an oscillating electric dipole is the source of a spin-2 field. Within this approximation to general relativity, it is shown that electromagnetic waves harbour gravitational waves.

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