Quantum Kaluza-Klein Cosmologies (V)

TL;DR

This paper demonstrates that in certain supergravity models within the No-boundary Universe framework, the observable universe must be four-dimensional, based on specific Kaluza-Klein compactifications, without relying on anthropic reasoning.

Contribution

It proves that under specific supergravity models, the universe's macroscopic dimension is necessarily four, providing a theoretical basis for our observed universe's dimensionality.

Findings

The seed instanton is a $S_7 imes S_4$ space.

The universe must be 4-dimensional in the considered models.

The result does not depend on anthropic principles.

Abstract

In the No-boundary Universe with $d=11$ supergravity, under the $S_n \times S_{11-n}$ Kaluza-Klein ansatz, the only seed instanton for the universe creation is a $S_7 \times S_4$ space. It is proven that for the Freund-Rubin, Englert and Awada-Duff-Pope models the macroscopic universe in which we are living must be 4- instead of 7-dimensional without appealing to the anthropic principle.