On the phenomenon of emergent spacetimes: An instruction guide for experimental cosmology

TL;DR

This paper introduces a toy model of emergent spacetime from microscopic systems, exploring a 'rainbow geometry' during rapid exponential growth, and discusses implications for quantum field theories with Lorentz-symmetry breaking.

Contribution

It proposes a novel 'rainbow geometry' framework for emergent spacetimes and analyzes its effects on cosmological particle production and experimental analogue cosmology.

Findings

Intermediate regime described by rainbow geometry during exponential growth

Cosmological particle production is temporarily sensitive to Lorentz invariance deviations

Quantitative estimates for experimental parameter regimes are provided

Abstract

We present a toy model where spacetime is emergent from a more fundamental microscopic system, and investigate the gray area interpolating between the collective and free-particle regimes. For a period of rapid exponential growth in the analogue universe, we argue that the intermediate regime is best described by a coloured potpourri of geometries -- a "rainbow geometry". This can be viewed as an alternative approach towards understanding quantum field theories in the presence of Lorentz-symmetry breaking at ultraviolet scales. Firstly, it is pointed out that cosmological particle production in our emergent FRW-type analogue universe, when compared to conventional semi-classical quantum gravity, is only temporarily robust against model-specific deviations from Lorentz invariance. Secondly, it is possible to carry out a straightforward quantitative analysis to estimate a suitable parameter regime for experimental (analogue) cosmology.