by Bernd Schneider

The Logic of Time Travel

Time travel is probably one of the most popular and most exciting topics in science fiction. The motivation for time travel is either to correct things that went wrong in the past or to see what our future will be like. However, the danger of causing a disturbance or even a paradox in the timeline appears to be great, especially when going to the past. A well-known problem is that if you travel e.g. 100 years to the past and (of course unintentionally) kill one of your forefathers, you extinct your own existence in the same moment. However, if you do not exist any more, there is no one to go back to the past to cause the change in the timeline. As a result, the timeline is ambiguous since that time in the past, and you exist and do not exist at the same time from a logical viewpoint.

To handle this so-called grandfather paradox was a challenge for many science fiction authors, and almost all of them failed to provide a credible description of the phenomenon and a logical explanation. What happens if a paradox occurs? Since a paradox cannot be solved, is it actually allowed? Is there a theory of time travel without paradox? My upcoming article will focus on the logical feasibility of time travel and not imply a physical or eventually a technical solution of the problem.

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Last changed: 21.01.98