Editing Time travel (section)

{{Short description|Hypothetical travel into the past or future}}
{{Other uses|Time Travel (disambiguation)}}
{{Pp-semi-indef}}
{{Use American English|date=May 2023}}
{{Use mdy dates|date=May 2023}}
[[File:The Time Machine – Frontpage Heinemann.png|thumb|The first page of ''[[The Time Machine]]'' published by [[Heinemann (publisher)|Heinemann]]]]
'''Time travel''' is the hypothetical activity of traveling into the [[past]] or [[future]]. Time travel is a concept in [[philosophy]] and [[fiction]], particularly [[science fiction]]. [[Time travel in fiction|In fiction]], time travel is typically achieved through the use of a device known as a [[Time machine (device)|time machine]]. The idea of a time machine was popularized by [[H. G. Wells]]'s 1895 novel ''[[The Time Machine]]''.<ref>{{cite book|title=Astounding Wonder: Imagining Science and Science Fiction in Interwar America|edition=illustrated|first1=John|last1=Cheng|publisher=University of Pennsylvania Press|year=2012|isbn=978-0-8122-0667-8|page=180|url=https://books.google.com/books?id=GoyzFw9UR8IC|access-date=2019-11-18|archive-date=2023-03-24|archive-url=https://web.archive.org/web/20230324181727/https://books.google.com/books?id=GoyzFw9UR8IC|url-status=live}} [https://books.google.com/books?id=GoyzFw9UR8IC&pg=PA180 Extract of page 180] {{Webarchive|url=https://web.archive.org/web/20230324181739/https://books.google.com/books?id=GoyzFw9UR8IC&pg=PA180 |date=2023-03-24 }}</ref>

It is uncertain whether time travel to the past would be physically possible. Such travel, if at all feasible, may give rise to questions of [[causality]]. Forward time travel, outside the usual sense of the [[Time perception|perception of time]], is an extensively observed phenomenon and is well understood within the framework of [[special relativity]] and [[general relativity]]. However, making one body advance or delay more than a few milliseconds compared to another body is not feasible with current technology. As for backward time travel, it is possible to find [[Exact solutions in general relativity|solutions in general relativity]] that allow for it, such as a rotating [[black hole]]. Traveling to an arbitrary point in spacetime has very limited support in [[theoretical physics]], and is usually connected only with [[Quantum mechanics of time travel|quantum mechanics]] or [[wormhole]]s.

{{anchor|History}}