Null energy condition and superluminal propagation
Sergei Dubovsky,Sergei Dubovsky,Thomas Gregoire,Thomas Gregoire,Alberto Nicolis,Riccardo Rattazzi +5 more
TLDR
In this paper, the null energy condition is violated in a large class of situations, including isotropic solids and fluids relevant for cosmology, and the existence of superluminal modes is shown to imply the presence of instabilities.Abstract:
We study whether a violation of the null energy condition necessarily implies the presence of instabilities. We prove that this is the case in a large class of situations, including isotropic solids and fluids relevant for cosmology. On the other hand we present several counter-examples of consistent effective field theories possessing a stable background where the null energy condition is violated. Two necessary features of these counter-examples are the lack of isotropy of the background and the presence of superluminal modes. We argue that many of the properties of massive gravity can be understood by associating it to a solid at the edge of violating the null energy condition. We briefly analyze the difficulties of mimicking u H > 0 in scalar tensor theories of gravity.read more
Citations
More filters
Journal ArticleDOI
Bouncing Galileon Cosmologies
TL;DR: In this article, nonsingular, homogeneous and isotropic bouncing solutions of the conformal Galileon model were presented, and it was shown that such solutions necessarily begin with a radiation-dominated contracting phase.
Journal ArticleDOI
Inflation and primordial non-Gaussianities of 'generalized Galileons'
TL;DR: In this paper, the power spectrum of the primordial curvature perturbation has been studied and a modification of the usual consistency relation of the tensor-to-scalar ratio in k-inflation or perfect fluid models has been proposed.
Journal ArticleDOI
Bouncing and accelerating solutions in nonlocal stringy models
TL;DR: In this paper, a general class of cosmological models driven by a nonlocal scalar field inspired by string field theories is studied, and a distinguished feature of these models is a crossing of the phantom divide.
Posted Content
Ultra-Light Dark Matter
TL;DR: In this article, the authors present a review of existing models of ULDM and classify them according to the different ways they achieve condensation, including Bose-Einstein condensate (BEC) and superfluidity.
Journal ArticleDOI
The quantum mechanics of perfect fluids
TL;DR: In this article, the authors consider the canonical quantization of an ordinary fluid and show that the resulting long-distance effective field theory is derivatively coupled, and therefore strongly coupled in the UV.
References
More filters
Book
The Large Scale Structure of Space-Time
TL;DR: In this paper, the authors discuss the General Theory of Relativity in the large and discuss the significance of space-time curvature and the global properties of a number of exact solutions of Einstein's field equations.
Journal ArticleDOI
Type Ia supernova discoveries at z > 1 from the Hubble Space Telescope: Evidence for past deceleration and constraints on dark energy evolution
Adam G. Riess,Louis-Gregory Strolger,John L. Tonry,Stefano Casertano,Henry C. Ferguson,Bahram Mobasher,Peter Challis,Alexei V. Filippenko,Saurabh Jha,Weidong Li,Ryan Chornock,Robert P. Kirshner,Bruno Leibundgut,Mark Dickinson,Mario Livio,Mauro Giavalisco,Charles C. Steidel,Txitxo Benítez,Zlatan Tsvetanov +18 more
TL;DR: For a flat universe with a cosmological constant, the transition between the two epochs is constrained to be at z = 0.46 ± 0.13 as mentioned in this paper, and w = -1.02 ± (and w < -0.76 at the 95% confidence level) for an assumed static equation of state of dark energy.
Journal ArticleDOI
Type Ia Supernova Discoveries at z>1 From the Hubble Space Telescope: Evidence for Past Deceleration and Constraints on Dark Energy Evolution
Adam G. Riess,Louis-Gregory Strolger,John L. Tonry,Stefano Casertano,Henry C. Ferguson,Bahram Mobasher,Peter Challis,Alexei V. Filippenko,Saurabh Jha,Weidong Li,Ryan Chornock,Robert P. Kirshner,Bruno Leibundgut,Mark Dickinson,Mario Livio,Mauro Giavalisco,Charles C. Steidel,Narciso Benítez,Zlatan Tsvetanov +18 more
TL;DR: In this article, the first conclusive evidence for cosmic deceleration that preceded the current epoch of cosmic acceleration was provided by the discovery of 16 Type Ia supernovae with the Hubble Space Telescope (HST).
Journal ArticleDOI
4D Gravity on a Brane in 5D Minkowski Space
TL;DR: In this article, the authors propose a mechanism by which four-dimensional Newtonian gravity emerges on a 3-brane in 5D Minkowski space with an infinite size extra dimension.