Big extra dimensions make Lambda too small

TL;DR

The paper argues that large extra dimensions cannot explain the observed dark energy because the quantum gravity scale must be close to the Planck length, challenging certain higher-dimensional models.

Contribution

It provides a theoretical argument linking the quantum gravity scale to dark energy and critiques large extra dimension scenarios based on this relation.

Findings

Large extra dimensions are incompatible with observed dark energy.

Quantum gravity fluctuations are sufficient to account for dark energy.

Higher-dimensional black hole entropy can be consistently interpreted in Kaluza-Klein theory.

Abstract

I argue that the true quantum gravity scale cannot be much larger than the Planck length, because if it were then the quantum gravity-induced fluctuations in $\Lam$ would be insufficient to produce the observed cosmic ``dark energy''. If one accepts this argument, it rules out scenarios of the ``large extra dimensions'' type. I also point out that the relation between the lower and higher dimensional gravitational constants in a Kaluza-Klein theory is precisely what is needed in order that a black hole's entropy admit a consistent higher dimensional interpretation in terms of an underlying spatio-temporal discreteness.