(Non)perturbative gravity, nonlocality, and nice slices

Giddings, Steven B.

doi:10.1103/physrevd.74.106009

Cited by 60 publications

(56 citation statements)

References 45 publications

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“…This would be in accord with the general nonlocality principle enunciated in [14,13], stating that the nonperturbative dynamics which unitarizes gravity is intrinsically nonlocal. One of the problems of formulating a suitable nonlocal mechanics is that of understanding how to characterize such states in this limit.…”

Section: Nonlocal Mechanics About Flat Spacesupporting

confidence: 60%

Universal quantum mechanics

Giddings

2008

Phys. Rev. D

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If gravity respects quantum mechanics, it is important to identify the essential postulates of a quantum framework capable of incorporating gravitational phenomena. Such a construct likely requires elimination or modification of some of the "standard" postulates of quantum mechanics, in particular those involving time and measurement. This paper proposes a framework that appears sufficiently general to incorporate some expected features of quantum gravity. These include the statement that space and time may only emerge approximately and relationally. One perspective on such a framework is as a sort of generalization of the S-matrix approach to dynamics. Within this framework, more dynamical structure is required to fully specify a theory; this structure is expected to lack some of the elements of local quantum field theory. Some aspects of this structure are discussed, both in the context of scattering of perturbations about a flat background, and in the context of cosmology. *

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Section: Nonlocal Mechanics About Flat Spacesupporting

confidence: 60%

Universal quantum mechanics

Giddings

2008

Phys. Rev. D

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“…In the present context the boundary F ∼ f in the field theory Fock space would represent a correspondence point where local field theory yields to such a new nonlocal theory needed for complete description of the quantum dynamics. In a flat background, this conjectured correspondence point is parametrized by the 'locality bound' proposed for two-particle states in [55,58,59] and in the N-particle case in [56]. If this perspective is correct, our bound F < f is thus naturally termed a 'de Sitter locality bound.'…”

Section: The Global Picture Of Eternal De Sitter Spacementioning

confidence: 89%

“…A proposed 'nonlocality principle' [54,55] suggests that the non-perturbative gravitational dynamics of this regime has essentially nonlocal large-scale behavior. This is supported by studies of high-energy scattering [56] and by investigating locality through relational observables [23,47], and could play an important role in explaining unitarity of black hole evaporation [54,55,57]. In the present context the boundary F ∼ f in the field theory Fock space would represent a correspondence point where local field theory yields to such a new nonlocal theory needed for complete description of the quantum dynamics.…”

Section: The Global Picture Of Eternal De Sitter Spacementioning

confidence: 99%

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A global picture of quantum de Sitter space

Giddings

Marolf

2007

Phys. Rev. D

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Perturbative gravity about a de Sitter background motivates a global picture of quantum dynamics in 'eternal de Sitter space,' the theory of states which are asymptotically de Sitter to both future and past. Eternal de Sitter physics is described by a finite dimensional Hilbert space in which each state is precisely invariant under the full de Sitter group. This resolves a previously-noted tension between de Sitter symmetry and finite entropy. Observables, implications for Boltzmann brains, and Poincaré recurrences are briefly discussed.

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“…The D-dimensional Froissart [37] bound states [38][39][40] that at E → ∞, for some function f (θ). While basic assumptions needed to derive these bounds, particularly the existence of a gap, are not strictly satisfied in gravitational scattering, it it tempting to conclude that violation of such expected bounds is associated with some essential nonlocality associated with non-perturbative gravitational dynamics [7,43].…”

Section: Discussionmentioning

confidence: 99%

Gravitational effects in ultrahigh-energy string scattering

2008

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Ultrahigh-energy string scattering is investigated to clarify the relative role of string and gravitational effects, and their possible contributions to nonlocal behavior. Different regimes can be characterized by varying the impact parameter at fixed energy. In the regime where momentum transfers reach the string scale, string effects appear subdominant to higher-loop gravitational processes, approximated via the eikonal. At smaller impact parameters, "diffractive" or "tidal" string excitation leads to processes dominated by highly excited strings. However, new evidence is presented that these excitation effects do not play a direct role in black hole formation, which corresponds to breakdown of gravitational perturbation theory and appears to dominate at sufficiently small impact parameters. The estimated amplitudes violate expected bounds on high-energy behavior for local theories. *

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(Non)perturbative gravity, nonlocality, and nice slices

Cited by 60 publications

References 45 publications

Universal quantum mechanics

Universal quantum mechanics

A global picture of quantum de Sitter space

Gravitational effects in ultrahigh-energy string scattering

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