Hyperfast Interstellar Travel in General Relativity

TL;DR

This paper explores the theoretical limits of interstellar travel within general relativity, concluding that while faster-than-light travel is impossible, extremely rapid round-trips may be feasible under certain conditions.

Contribution

It introduces a framework for analyzing interstellar travel in general relativity, showing the constraints and possibilities of controlling spacetime geometry for rapid journeys.

Findings

Travel cannot surpass light speed in reaching a destination.

Longer round-trips can be completed in arbitrarily short terrestrial time.

Travel constraints are governed by the properties of globally hyperbolic spacetimes.

Abstract

The problem is discussed of whether a traveller can reach a remote object and return back sooner than a photon would when taken into account that the traveller can partly control the geometry of his world. It is argued that under some reasonable assumptions in globally hyperbolic spacetimes the traveller cannot hasten reaching the destination. Nevertheless, it is perhaps possible for him to make an arbitrarily long round-trip within an arbitrarily short (from the point of view of a terrestrial observer) time.