Lorentz violation and perpetual motion

Eling, Christopher; Foster, Brendan; Jacobson, Ted; Wall, Aron C.

doi:10.1103/physrevd.75.101502

Cited by 89 publications

(145 citation statements)

References 21 publications

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“…The surface gravity at the universal horizon is [43] 8) which depends on the specific dispersion relation. So the associated black hole temperature looses its universal meaning for all species of particles, then such black hole would therefore not be in equilibrium and hence, conflicts with the "zeroth law" and the generalized second law [38].…”

Section: Dispersion Relation and Group Velocitymentioning

confidence: 99%

Dispersion relation and surface gravity of universal horizons

Ding¹,

Liu²

2017

Sci. China Phys. Mech. Astron.

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Section: Dispersion Relation and Group Velocitymentioning

confidence: 99%

Dispersion relation and surface gravity of universal horizons

Ding¹,

Liu²

2017

Sci. China Phys. Mech. Astron.

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“…Also for any value of λ GB , the graviton cone coincides with the light cone in the radial direction. If not, we could have argued for the violation of the second law of thermodynamics following [46,47]. Further note that for λ GB < − 1 8 , there exists a region outside the horizon where c 2 g < 0 which will lead to the appearance of tachyonic modes, following [48].…”

Section: A Graviton Cone Tippingmentioning

confidence: 99%

Viscosity bound violation in higher derivative gravity

et al. 2008

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Motivated by the vast string landscape, we consider the shear viscosity to entropy density ratio in conformal field theories dual to Einstein gravity with curvature square corrections. After field redefinitions these theories reduce to Gauss-Bonnet gravity, which has special properties that allow us to compute the shear viscosity nonperturbatively in the Gauss-Bonnet coupling. By tuning of the coupling, the value of the shear viscosity to entropy density ratio can be adjusted to any positive value from infinity down to zero, thus violating the conjectured viscosity bound. At linear order in the coupling, we also check consistency of four different methods to calculate the shear viscosity, and we find that all of them agree. We search for possible pathologies associated with this class of theories violating the viscosity bound.

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“…Another model which has attracted considerable attention is the ghost condensate [445], which can be used to violate the null energy condition and constuction bouncing cosmologies [239,446,447]. It has been argued that the ghost condensate is in conflict with the 2 nd law of black hole thermodynamics [448,449]. (See [450] for a dissenting viewpoint.)…”

Section: Kinetic Screeningmentioning

confidence: 99%

Beyond the cosmological standard model

et al. 2015

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After a decade and a half of research motivated by the accelerating universe, theory and experiment have a reached a certain level of maturity. The development of theoretical models beyond Λ or smooth dark energy, often called modified gravity, has led to broader insights into a path forward, and a host of observational and experimental tests have been developed. In this review we present the current state of the field and describe a framework for anticipating developments in the next decade. We identify the guiding principles for rigorous and consistent modifications of the standard model, and discuss the prospects for empirical tests.We begin by reviewing recent attempts to consistently modify Einstein gravity in the infrared, focusing on the notion that additional degrees of freedom introduced by the modification must "screen" themselves from local tests of gravity. We categorize screening mechanisms into three broad classes: mechanisms which become active in regions of high Newtonian potential, those in which first derivatives of the field become important, and those for which second derivatives of the field are important. Examples of the first class, such as f (R) gravity, employ the familiar chameleon or symmetron mechanisms, whereas examples of the last class are galileon and massive gravity theories, employing the Vainshtein mechanism. In each case, we describe the theories as effective theories and discuss prospects for completion in a more fundamental theory. We describe experimental tests of each class of theories, summarizing laboratory and solar system tests and describing in some detail astrophysical and cosmological tests. Finally, we discuss prospects for future tests which will be sensitive to different signatures of new physics in the gravitational sector.The review is structured so that those parts that are more relevant to theorists vs. observers/experimentalists are clearly indicated, in the hope that this will serve as a useful reference for both audiences, as well as helping those interested in bridging the gap between them.

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Lorentz violation and perpetual motion

Cited by 89 publications

References 21 publications

Dispersion relation and surface gravity of universal horizons

Dispersion relation and surface gravity of universal horizons

Viscosity bound violation in higher derivative gravity

Beyond the cosmological standard model

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