Strings in the Einstein's paradigm of matter

TL;DR

The paper explores flux tube solutions in Kaluza-Klein gravity that resemble strings connecting two Universes, with gravitational wave propagation on these threads similar to classical string equations, suggesting a string-like nature of these structures.

Contribution

It demonstrates that flux tubes in Kaluza-Klein gravity under certain conditions behave like strings connecting Universes, with gravitational wave dynamics akin to classical string equations.

Findings

Flux tubes resemble strings stretched between Universes.

Propagation of gravitational waves on the flux tube matches classical string equations.

Flux tubes can be modeled as 1-dimensional threads with Planck-scale cross section.

Abstract

Spherically symmetric solutions with a flux of electric and magnetic fields in Kaluza-Klein gravity are considered. It is shown that under the condition (electric charge $q$) $\approx$ (magnetic charge $Q$) ($q>Q$) these solutions are like a flux tube stretched between two Universes. The longitudinal size of this tube depends on the value of $\delta = 1 - Q/q$. The cross section of the tube can be chosen $\approx l_{Pl}$. In this case this flux tube looks like a 1-dimensional object (thread) stretched between two Universes. The propagation of gravitational waves on the thread is considered. The corresponding equations are very close to the classical string equations. This result allows us to say that the thread between two Universes is similar to the string attached to two $D-$branes.