Temporal paradox
[9][6][12] A notable example occurs in the 1958 science fiction short story "—All You Zombies—", by Robert A. Heinlein, wherein the main character, an intersex individual, becomes both their own mother and father; it was adapted with great fidelity in the 2014 film Predestination.For example, the philosopher Bradley Dowden made this sort of argument in the textbook Logical Reasoning, arguing that the possibility of creating a contradiction rules out time travel to the past entirely.[30]: 4 He does not find these paradoxical and attributes problems regarding the validity of time travel to other factors in the interpretation of general relativity.[30]: 14–16 A 1992 paper by physicists Andrei Lossev and Igor Novikov labeled such items without origin as Jinn, with the singular term Jinnee."[30]: 8–9 The self-consistency principle developed by Igor Dmitriyevich Novikov[33]: p. 42 note 10 expresses one view as to how backward time travel would be possible without the generation of paradoxes.According to this hypothesis, even though general relativity permits some exact solutions that allow for time travel[34] that contain closed timelike curves that lead back to the same point in spacetime,[35] physics in or near closed timelike curves (time machines) can only be consistent with the universal laws of physics, and thus only self-consistent events can occur.The authors concluded that time travel need not lead to unresolvable paradoxes, regardless of what type of object was sent to the past.[37] Later analysis by Thorne and Robert Forward showed that for certain initial trajectories of the billiard ball, there could be an infinite number of self-consistent solutions.Visser views causal loops and Novikov's self-consistency principle as an ad hoc solution, and supposes that there are far more damaging implications of time travel.[30]: 14–16 Another conjecture, the cosmic censorship hypothesis, suggests that every closed timelike curve passes through an event horizon, which prevents such causal loops from being observed.[42] 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.
Temporal paradox (paleontology)paradoxtime traveltime dilationcausal loop diagramtime loopbootstrappinggrandfather paradoxNewcomb's paradoxfree willretrocausalityspacetimescience fictionshort story—All You Zombies—Robert A. HeinleinintersexPredestinationSomewhere in TimeNovikov self-consistency principleAmazing StoriesAdolf HitlerWorld War IIthe Holocaustthought experimentexpected utilitystrategic dominancecausalitysupernaturalmodal logicBradley DowdenNorman SwartzGödel metricKurt Gödelblock timeSergey KrasnikovIgor Novikovsecond law of thermodynamicsIgor Dmitriyevich Novikovgeneral relativityexact solutionsclosed timelike curvesJoseph Polchinskibilliard ballwormholeKip ThorneRobert Forwardchronology-violating region of spacetimecosmic censorship hypothesisevent horizonmany-worlds interpretationchronology protection conjectureDavid Deutschquantum computationstatistical mechanicsQuantum mechanics of time travelFermi paradoxCausal structureMünchhausen trilemmaTime travel in fictionBibcodeMcFarland & CompanySyntheseCraig, William LaneThe Journal of PhilosophyThorne, Kip S.Black Holes and Time WarpsDeutsch, DavidClosed timelike curvein science fictionin filmCausal loopAlternate historyMultiverseParallel universes in fictionPhilosophy of space and timeButterfly effectDeterminismEternalismFatalismSpacetimesAlcubierre metricBTZ black holeKerr metricKrasnikov tubeMisner spaceTipler cylindervan Stockum dust