Editing Temporal paradox (section)

==== Parallel universes ====
The interacting-multiple-universes approach is a variation of the [[many-worlds interpretation]] of quantum mechanics that involves time travelers arriving in a different universe than the one from which they came; it has been argued that, since travelers arrive in a different universe's history and not their history, this is not "genuine" time travel.<ref name="Stanford time travel">{{citation |author1=Frank Arntzenius |title=Time Travel and Modern Physics |date=December 23, 2009 |url=http://plato.stanford.edu/entries/time-travel-phys/ |encyclopedia=Stanford Encyclopedia of Philosophy |access-date=May 25, 2019 |author2=Tim Maudlin}}</ref> Stephen Hawking has argued for the [[chronology protection conjecture]], that even if the MWI is correct, we should expect each time traveler to experience a single self-consistent history so that time travelers remain within their world rather than traveling to a different one.<ref name="Hawking warp">{{cite web |last1=Hawking |first1=Stephen |year=1999 |title=Space and Time Warps |url=http://www.hawking.org.uk/space-and-time-warps.html |access-date=February 25, 2012 |archive-date=February 10, 2012 |archive-url=https://web.archive.org/web/20120210233225/http://www.hawking.org.uk/space-and-time-warps.html |url-status=dead }}</ref>

[[David Deutsch]] has proposed that [[quantum computation]] with a negative delay—backward time travel—produces only self-consistent solutions, and the chronology-violating region imposes constraints that are not apparent through classical reasoning.<ref name="Deutsch">{{cite journal |last1=Deutsch |first1=David |author-link=David Deutsch |date=15 November 1991 |title=Quantum mechanics near closed timelike lines |journal=Physical Review D |volume=44 |issue=10 |pages=3197–3217 |bibcode=1991PhRvD..44.3197D |doi=10.1103/PhysRevD.44.3197 |pmid=10013776}}</ref> However Deutsch's self-consistency condition has been demonstrated as capable of being fulfilled to arbitrary precision by any system subject to the laws of classical [[statistical mechanics]], even if it is not built up by quantum systems.<ref>{{cite journal |last1=Tolksdorf |first1=Juergen |last2=Verch |first2=Rainer |date=2021 |title=The D-CTC condition is generically fulfilled in classical (non-quantum) statistical systems |journal=Foundations of Physics |series= |volume=51 |issue=93 |page=93 |arxiv=1912.02301 |bibcode=2021FoPh...51...93T |doi=10.1007/s10701-021-00496-z |authorlink2= |authorlink1= |s2cid=208637445}}</ref> Allen Everett has also argued that even if Deutsch's approach is correct, it would imply that any macroscopic object composed of multiple particles would be split apart when traveling back in time, with different particles emerging in different worlds.<ref name="Everett MWI">{{cite journal |last=Everett |first=Allen |year=2004 |title=Time travel paradoxes, path integrals, and the many worlds interpretation of quantum mechanics |journal=Physical Review D |volume=69 |issue=124023 |pages=124023 |arxiv=gr-qc/0410035 |bibcode=2004PhRvD..69l4023E |doi=10.1103/PhysRevD.69.124023 |s2cid=18597824}}</ref>