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Analogue Gravity
 Living Rev. Rel
"... Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particu ..."
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Cited by 66 (23 self)
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Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particularly simple example of an analogue model, before exploring the rich history and complex tapestry of models discussed in the literature. The last decade in particular has seen a remarkable and sustained development of analogue gravity ideas, leading to some hundreds of published articles, a workshop, two books, and this review article. Future prospects for the analogue gravity programme also look promising, both on the experimental front (where technology is rapidly advancing) and on the theoretical front (where variants of analogue models can be used as a springboard for radical attacks on the problem
Causal structure of acoustic spacetimes
"... The socalled “analogue models of general relativity ” provide a number of specific physical systems, well outside the traditional realm of general relativity, that nevertheless are welldescribed by the differential geometry of curved spacetime. Specifically, the propagation of acoustic disturbance ..."
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Cited by 10 (5 self)
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The socalled “analogue models of general relativity ” provide a number of specific physical systems, well outside the traditional realm of general relativity, that nevertheless are welldescribed by the differential geometry of curved spacetime. Specifically, the propagation of acoustic disturbances in moving fluids are described by “effective metrics ” that carry with them notions of “causal structure ” as determined by an exchange of sound signals. These acoustic causal structures serve as specific examples of what can be done in the presence of a Lorentzian metric without having recourse to the Einstein equations of general relativity. (After all, the underlying fluid mechanics is governed by the equations of traditional hydrodynamics, not by the Einstein equations.) In this article we take a careful look at what can be said about the causal structure of acoustic spacetimes, focusing on those containing sonic points or horizons, both with a view to seeing what is different from standard general relativity, and to seeing what the similarities might be.
Emergent Models for Gravity: an Overview of Microscopic Models
, 2012
"... We give a critical overview of various attempts to describe gravity as an emergent phenomenon, starting from examples of condensed matter physics, to arrive to more sophisticated pregeometric models. The common line of thought is to view the graviton as a composite particle/collective mode. Howeve ..."
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We give a critical overview of various attempts to describe gravity as an emergent phenomenon, starting from examples of condensed matter physics, to arrive to more sophisticated pregeometric models. The common line of thought is to view the graviton as a composite particle/collective mode. However, we will describe many different ways in which this idea is realized in practice.
On the phenomenon of emergent spacetimes: An instruction guide for experimental cosmology
, 2008
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Experimental quantum cosmology in timedependent optical media
 New J.Phys
"... Abstract. It is possible to construct artificial spacetime geometries for light by using intense laser pulses that modify the spatiotemporal properties of an optical medium. Here we theoretically investigate experimental possibilities for studying spacetime metrics of the form ds2 = c2dt2 − η(t)2dx2 ..."
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Abstract. It is possible to construct artificial spacetime geometries for light by using intense laser pulses that modify the spatiotemporal properties of an optical medium. Here we theoretically investigate experimental possibilities for studying spacetime metrics of the form ds2 = c2dt2 − η(t)2dx2. By tailoring the laser pulse shape and medium properties, it is possible to create a refractive index variation n = n(t) that can be identified with η(t). Starting from a perturbative solution to a generalised Hopfield model for the medium described by an n = n(t) we provide estimates for the number of photons generated by the timedependent spacetime. The simplest example is that of a uniformly varying η(t) that therefore describes the RobertsonWalker metric, i.e. a cosmological expansion. The number of photon pairs generated in experimentally feasible conditions appears to be extremely small. However, large photon production can be obtained by periodically modulating the medium and thus resorting to a resonant enhancement similar to that observed in the dynamical Casimir effect. Curiously, the spacetime metric in this case closely resembles that of a gravitational wave. Motivated by this analogy we show that a periodic gravitational wave can indeed act as an amplifier for photons. The emission for an actual gravitational wave will be very weak but should be readily observable in the laboratory analogue.
EMERGENT GRAVITY: The Analogue Models Perspective
, 2009
"... This thesis is devoted to the study of some aspects of emergent gravity scenarios, i.e. of nongravitational systems which exhibit, under suitable conditions, the emergence of effective spacetime metrics and the associated gravitational dynamics. While this area of research is rather broad, we will ..."
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This thesis is devoted to the study of some aspects of emergent gravity scenarios, i.e. of nongravitational systems which exhibit, under suitable conditions, the emergence of effective spacetime metrics and the associated gravitational dynamics. While this area of research is rather broad, we will assume a particular perspective: the starting point is the discussion of analogue models for gravity, which have so far provided precious insights on aspects of physics on curved spacetimes, on extensions of Riemannian geometry and on the possible role of high energy Lorentz symmetry violations in low energy physics. The first part is devoted to the study of the most relevant kinematical features of emergent spacetimes typical of condensed matter analogue models. In particular, it will be shown that a natural framework for the description of the geometrical properties of emergent spacetimes is Finsler geometry, which thus represent an interesting candidate for extensions of special (and eventually general) relativity. We will present the basic concepts of this particular generalization of Riemannian geometry, and hence we will pass to the careful analysis of the main issues to be solved and of the features that can be of major interest for physical applications, in particular the geometrical interpretation of modified dispersion relations and the fate of Lorentz symmetry at the Planck scale. Some emphasis will be given to the conditions under which pseudoRiemannian geometries
Living Reviews in Relativity
, 2005
"... Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particu ..."
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Cited by 1 (0 self)
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Analogue models of (and for) gravity have a long and distinguished history dating back to the earliest years of general relativity. In this review article we will discuss the history, aims, results, and future prospects for the various analogue models. We start the discussion by presenting a particularly simple example of an analogue model, before exploring the rich history and complex tapestry of models discussed in the literature. The last decade in particular has seen a remarkable and sustained development of analogue gravity ideas, leading to some hundreds of published articles, a workshop, two books, and this review article. Future prospects for the analogue gravity programme also look promising, both on the experimental front (where technology is rapidly advancing) and on the theoretical front (where variants of analogue models can be used as a springboard for radical attacks on the problem of quantum gravity). c○Max Planck Society and the authors. Further information on copyright is given at