Brane Formation and Cosmological Constraint on the Number of Extra Dimensions

TL;DR

This paper explores how branes may have formed later in the universe's history rather than existing from the start, using generalized relativity in extra dimensions and deriving constraints on their number.

Contribution

It introduces a scenario where branes form after the early universe, challenging standard cosmology, and provides a lower bound of seven on the number of extra dimensions.

Findings

Branes may have formed after the universe's initial state.

Particles initially filled the entire bulk before brane formation.

A lower bound of N ≥ 7 on extra dimensions is derived.

Abstract

Special relativity is generalized to extra dimensions and quantized energy levels of particles are obtained. By calculating the probability of particles' motion in extra dimensions at high temperature of the early universe, it is proposed that the branes may have not existed since the very beginning of the universe, but formed later. Meanwhile, before the formation, particles of the universe may have filled in the whole bulk, not just on the branes. This scenario differs from that in the standard big bang cosmology in which all particles are assumed to be in the 4D spacetime. So, in brane models, whether our universe began from a 4D big bang singularity is questionable. A cosmological constraint on the number of extra dimensions is also given which favors $N\geq 7$.