# Cosmology in the laboratory: an analogy between hyperbolic metamaterials and the Milne universe

## TL;DR

This paper demonstrates that hyperbolic metamaterials can simulate the geometry of the Milne universe, enabling experimental exploration of cosmological phenomena like the big bang/big crunch transition.

## Contribution

It introduces a novel analogy between hyperbolic metamaterials and the Milne universe, allowing laboratory experiments to mimic cosmological models.

## Key findings

- Metamaterials replicate Milne universe geometry for light propagation.
- Wave and ray optics in metamaterials mimic particle trajectories and wave functions.
- Potential for experimental tests of cosmic singularity phenomena.

## Abstract

This article shows that the compactified Milne universe geometry, a toy model for the big crunch/big bang transition, can be realized in hyperbolic metamaterials, a new class of nanoengineered systems which have recently found its way as an experimental playground for cosmological ideas. On one side, Klein-Gordon particles, as well as tachyons, are used as probes of the Milne geometry. On the other side, the propagation of light in two versions of a liquid crystal-based metamaterial provides the analogy. It is shown that ray and wave optics in the metamaterial mimic, respectively, the classical trajectories and wave function propagation, of the Milne probes, leading to the exciting perspective of realizing experimental tests of particle tunneling through the cosmic singularity, for instance.