PreprintarXiv licencearXiv
Cosmology of the Baby Universe in Coupled SYK
Abstract
We analyze the structure of the baby universe which arises in the coupled SYK realization of the AS2 geometry. To do this, we develop and leverage combinatorial arguments about traces of many Majoranas which remain valid at finite N and p and thus furnish the finite λ completion of the chord rules found in [1]. We find that there is a first order phase transition which persists in the β→∞ limit between the thermal AdS and AS2 phases parameterized by the mass of the heavy particle insertion and the ratio between the SYK and Maldacena-Qi coupling constants. We then explore Lorentzian time evolution in the baby universe and find a cosine scale factor confirming the big bang / big crunch nature of the bulk cosmology.
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BibTeX
@misc{sontag2026cosmology,
title = {{Cosmology of the Baby Universe in Coupled SYK}},
author = {Andrew Sontag},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.36032},
eprint = {2610.36032},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.36032},
}
RIS
TY - UNPB
TI - Cosmology of the Baby Universe in Coupled SYK
AU - Andrew Sontag
PY - 2026
DA - 2026/10/26
PB - arXiv
DO - 10.48550/arxiv.2610.36032
UR - https://arxiv.org/abs/2610.36032
AB - We analyze the structure of the baby universe which arises in the coupled SYK realization of the AS^2 geometry. To do this, we develop and leverage combinatorial arguments about traces of many Majoranas which remain valid at finite N and p and thus furnish the finite λ completion of the chord rules found in [1]. We find that there is a first order phase transition which persists in the β→∞ limit between the thermal AdS and AS^2 phases parameterized by the mass of the heavy particle insertion and the ratio between the SYK and Maldacena-Qi coupling constants. We then explore Lorentzian time evolution in the baby universe and find a cosine scale factor confirming the big bang / big crunch nature of the bulk cosmology.
ER -