Gravity as an emergent phenomenon: a GFT perspective

While the idea of gravity as an emergent phenomenon is an intriguing one, little is known about concrete implementations that could lead to viable phenomenology, most of the obstructions being related to the intrinsic difficulties of formulating genuinely pregeometric theories. In this paper we present a preliminary discussion of the impact of critical behavior of certain microscopic models for gravity, based on group field theories, on the dynamics of the macroscopic regime. The continuum limit is examined in light of some scaling assumption, and the relevant consequences for low energy effective theories are discussed, the role of universality, the corrections to scaling, the emergence of gravitational theories and the nature of their thermodynamical behavior.Comment: 1+26 page

A note on particle kinematics in Horava-Lifshitz scenarios

In this short note we clarify a link between anisotropic-scaling scenarios and Finsler spacetimes. Generalizing earlier analysis it is shown that the kinematics of propagating particles (in the sense of geometrical optics) can be described in terms of (pseudo-)Finsler structures.Comment: 8 pages. Revised version: some references have been adde

Emergent gravitational dynamics from multi-BEC hydrodynamics?

In this paper, we examine the possibility to implement some form of emergent Newtonian gravity in a generic multi-component Bose--Einstein condensate. Parallely to what happens for the emergence of low energy Lorentz invariance, strong requirements have to be imposed on the underlying condensed matter model. We will show, within a simplified model, that the presence of a global symmetry alleviates the problems associated to Lorentz violation, allows the presence of a long range potential, to which the analogue matter fields (the quasi-particles) are coupled following a weaker form of equivalence principle.Comment: revtex4, 23 page

Horizon thermodynamics and composite metrics

We examine the conditions under which the thermodynamic behaviour of gravity can be explained within an emergent gravity scenario, where the metric is defined as a composite operator. We show that due to the availability of a boundary of a boundary principle for the quantum effective action, Clausius-like relations can always be constructed. Hence, any true explanation of the thermodynamic nature of the metric tensor has to be referred to an equilibration process, associated to the presence of an H-theorem, possibly driven by decoherence induced by the pregeometric degrees of freedom, and their entanglement with the geometric ones.Comment: 11 pages, 1 figur

New coherent states and modified heat equations

We clarify the relations between certain new coherent states for loop quantum gravity and the analytically continued heat kernel coherent states, highlighting the underlying general construction, the presence of a modified heat equation as well as the way in which the properties of the heat kernels are automatically inherited by these new states.Comment: 7 page

Emergent gravitational dynamics in Bose-Einstein condensates

We discuss a toy model for an emergent non-relativistic gravitational theory. Within a certain class of Bose-Einstein condensates, it is possible to show that, in a suitable regime, a modified version of non-relativistic Newtonian gravity does effectively describes the low energy dynamics of the coupled system condensate/quasi-particles.Comment: 9 pages. To appear in the Proceedings of the XXV Max Born Symposium, "The Planck Scale", Wroclaw, Poland, July 200