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Time travel

DOI: 10.4324/9780415249126-Q108-1
Version: v1,  Published online: 1998
Retrieved May 21, 2019, from

Article Summary

The prospect of a machine in which one could be transported through time is no longer mere fantasy, having become in this century the subject of serious scientific and philosophical debate. From Einstein’s special theory of relativity we have learned that a form of time travel into the future may be accomplished by moving quickly, and therefore ageing slowly (exploiting the time dilation effect). And in 1949 Kurt Gödel announced his discovery of (general relativistic) spacetimes whose global curvature allows voyages into the past as well. Since then the study of time travel has had three main strands. First, there has been research by theoretical physicists into the character and plausibility of structures, beyond those found by Gödel, that could engender closed timelike lines and closed causal chains. These phenomena include rotating universes, black holes, traversable wormholes and infinite cosmic strings (Earman 1995). Second, there has been concern with the semantic issue of whether the terms ‘cause’, ‘time’ and ‘travel’ are applicable, strictly speaking, to such bizarre models, given how different they are from the contexts in which those terms are normally employed (Yourgrau 1993). However, one may be sceptical about the significance of this issue, since the questions of primary interest – focused on the nature and reality of the Gödel-style models – seem independent of whether their description requires a shift in the meanings of those words. And, third, there has been considerable discussion within both physics and philosophy of various alleged paradoxes of time travel, and of their power to preclude the spacetime models in which time travel could occur.

Citing this article:
Horwich, Paul. Time travel, 1998, doi:10.4324/9780415249126-Q108-1. Routledge Encyclopedia of Philosophy, Taylor and Francis,
Copyright © 1998-2019 Routledge.

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