Tides across thin-shells: differences between spacetimes with one and two asymptotic regions

TL;DR

This paper examines how tidal forces across thin shells differ between spacetimes with one or two asymptotic regions, revealing that certain problematic tides can be mitigated in one-region spacetimes, especially with cylindrical shells.

Contribution

It demonstrates that tidal issues associated with curvature jumps are less restrictive in spacetimes with one asymptotic region and highlights the advantage of cylindrical shells over spherical ones.

Findings

Tidal problems are reduced or canceled in one-asymptotic-region spacetimes.

Cylindrical shells offer advantages over spherical shells in tidal considerations.

Curvature jumps across shells influence tidal forces and traversability.

Abstract

Traversability across thin shells is investigated, with special attention devoted to the difference in tides related with different global properties of the geometries. While we have recently associated curvature jumps across infinitely thin shells to troublesome tides and consequent very restrictive conditions for a safe travel across a throat satisfying the flare-out condition in spacetimes with two asymptotic regions, now we find that analogous problems can be significantly reduced or even cancelled across shells joining an inner with an outer submanifold of spacetimes with one asymptotic region. We also show that, within this framework, cylindrical shells present an advantage over spherical shells.