Geodesic completion of big bangs from emergent geometry
Abstract
Chaplygin gas and other k-essence models exhibit emergent geometry, with perturbations propagating on an acoustic metric disformally related to the Einstein-frame metric. For superluminal sound speed, we identify the disformal metric as the "causal frame," since choosing a finite causal-frame lapse yields hyperbolic equations of motion for fields propagating in either frame. We show that with a phantom Chaplygin gas, the Einstein-frame lapse is forced to pass smoothly through zero and change sign while the causal-frame lapse remains positive. As a result, Einstein-frame degrees of freedom (including the scale factor) undergo spontaneous time-reversal while the Chaplygin gas evolves monotonically, enforcing a robust non-singular bounce even in the presence of additional matter canonically coupled to the Einstein frame.
Cite
@article{arxiv.2602.21642,
title = {Geodesic completion of big bangs from emergent geometry},
author = {Brooke Berrios and Cameron Corley and Sky O'Donnell and Benjamin Shlaer and Jada Young},
journal= {arXiv preprint arXiv:2602.21642},
year = {2026}
}
Comments
4 pages, 2 figures. Version accepted by Phys. Rev. D as a Letter