Topological censorship and chronology protection

Friedman, John L.; Higuchi, Atsushi

doi:10.1002/andp.200651801-209

Cited by 6 publications

(2 citation statements)

References 116 publications

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“…However, already quantum mechanics (i.e., nonrelativistic quantum theory) in such a background displays unusual features, and various conditions on the quantum system [56] or even modifications of the postulates of quantum theory have been proposed to deal with these [57,58]. The required conditions and/or modifications can then be generalized to quantum field theory, see for example the review [59] or Refs. [60,61] and references therein.…”

Section: Discussionmentioning

confidence: 99%

Strict deformations of quantum field theory in de Sitter spacetime

Fröb

Much

2021

Journal of Mathematical Physics

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We show that a non-commutative structure arises naturally from perturbative quantum gravity in a de Sitter background metric. Our work builds on recent advances in the construction of observables in highly symmetric background spacetimes [Brunetti et al., JHEP 08, 032 (2016); Fröb and Lima, Class. Quant. Grav. 35, 095010 (2018)], where the dynamical coordinates that are needed in the relational approach were established for such backgrounds to all orders in perturbation theory. We show that these dynamical coordinates that describe events in the perturbed spacetime are naturally non-commuting, and determine their commutator to leading order in the Planck length. Our result generalizes the causal non-commutative structure that was found using the same approach in Minkowski space [Fröb, Much and Papadopoulos, Phys. Rev. D 107, 064041 (2023)].

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Section: Discussionmentioning

confidence: 99%

Strict deformations of quantum field theory in de Sitter spacetime

Fröb

Much

2021

Journal of Mathematical Physics

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“…Only for affine parameters, since the relation between differing affine parameters is then very tightly constrained (via an affine rescaling λ → aλ + b), is the positivity of the ANEC an invariant concept. Carefully formulating the ANEC (or its variants) is, in turn, essential for understanding the relevant singularity theorems [42][43][44][45][46][47][48][49][50][51][52], topological censorship [53][54][55][56][57][58][59][60], and/or Hawking's chronology protection conjecture [61][62][63][64][65][66][67][68]. Further afield, the use of null affine parameters is extremely common in ongoing research, both theoretical and observational, such as, for instance, in .…”

Section: Introductionmentioning

confidence: 99%

Efficient Computation of Null Affine Parameters

Visser

2023

Universe

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Finding affine parameters for null geodesics is often of considerable physical importance, especially when studying null geodesics or dealing with conservation laws and/or averaged energy conditions. But explicitly finding null affine parameters is also often quite tedious and can sometimes even be somewhat tricky. Herein we shall demonstrate that the existence of a conformally related spacetime containing a conformal Killing vector, timelike in the domain of outer communication, is quite sufficient to define a preferred set of spatial three-slices—on which a well-defined “affine” three-metric can be introduced to capture the notion of affine null parameter—before explicitly finding the null geodesics. The construction depends on the properties of conformal transformations and on the conserved quantity associated with the conformal Killing vector. Having the affine null parameter in hand before attempting to find the actual null geodesics often quite radically simplifies other parts of the analysis. We emphasize that the successful identification of affine null parameters is a general-purpose tool of wide applicability in both general relativistic and astrophysical settings.

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Closed timelike curves and energy conditions in regular spacetimes

2022

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In this article, we explore the relationship between the existence of closed timelike curves and energy conditions that occur in the Kerr–Newman spacetime. To quantify the dependence, we define a correlation index between energy conditions and closed timelike curves. We investigate the validity of Hawking’s chronology protection conjecture for the closed time like curves that occur in the noncommutative version of the Kerr–Newman spacetime that has the right ingredients to examine the conjecture . We report the results outlining the possible role played by violations of energy conditions in eliminating the closed timelike curves.

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Topological censorship and chronology protection

Cited by 6 publications

References 116 publications

Strict deformations of quantum field theory in de Sitter spacetime

Strict deformations of quantum field theory in de Sitter spacetime

Efficient Computation of Null Affine Parameters

Closed timelike curves and energy conditions in regular spacetimes

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