Thetime loop ortemporal loop is aplot device infiction wherebycharacters re-experience a span of time which is repeated, sometimes more than once, with some hope of breaking out of the cycle of repetition.[1] Time loops are constantly resetting; when a certain condition is met, such as a death of a character or a certain point in time, the loop starts again, possibly with one or more characters retaining the memories from the previous loop.[2]
A time loop is also sometimes used to describe a scenario involving time travel where events form a circular chain of causality. In this context, actions in the past lead to future events, which then trigger the original journey back in time, creating a self-contained loop without a clear starting point. This concept challenges the conventional linear view of time and is often explored in science fiction and theories of temporal physics, such as those involving closed timelike curves.[1]
An early example of a time loop is the 1915 Russian novelStrange Life of Ivan Osokin, where the main character gets to live his life over again but struggles to change it the second time around.[3] The episode "The Man Who Murdered Time" in the radio dramaThe Shadow was broadcast on 1 January 1939, about a dying scientist who invents a time machine stuck on 31 December.[4][5] Theshort story "Doubled and Redoubled" byMalcolm Jameson that appeared in the February 1941Unknown tells of a person accidentally cursed to repeat a "perfect" day, including a lucky bet, a promotion, a heroically foiledbank robbery, and a successful wedding proposal.[6]
More recent examples include the 1973 short story "12:01 PM" and its1990 and1993 film adaptations, the Soviet filmMirror for a Hero (1988),[7] theStar Trek: The Next Generation episode "Cause And Effect" (1992),[8] theAmerican filmsGroundhog Day (1993),Naked (2017),Happy Death Day (2017),Happy Death Day 2U (2019), andPalm Springs (2020),[9] theBritish,found footage,psychological,analog horrorweb seriesNo Through Road (2009–2012),[10][11] the Danish series of novelsOm udregning af rumfang (On The Calculation of Volume) (2020- ),[12] and theIndian,Tamil-language,science fiction,politicalaction thriller filmMaanaadu.[13][14] Time loops have been used as a recurring theme inDoctor Who, with the episode "Heaven Sent" being described as "Doctor Who's definitive loop-based story".[15]
The time loop is a popular trope inJapanese pop culture media, especiallyanime.[16] Its use inJapanese fiction dates back toYasutaka Tsutsui'sscience fiction novelThe Girl Who Leapt Through Time (1965), one of the earliest works to feature a time loop, about a high school girl who repeatedly relives the same day. It was later adapted into a 1972 live-actionJapanese television series, a hit1983 live-action film, a2006 anime film, and a2010 live-action film.[17][18][19] The 1983 live-action film adaptation ofThe Girl Who Leapt Through Time was a major box office success in Japan,[19] where it was the secondhighest-grossing Japanese film of 1983.[20] Its success was soon followed by numerous anime and manga using the time loop concept, starting withMamoru Oshii's anime filmUrusei Yatsura 2: Beautiful Dreamer (1984), and then the manga and anime seriesKimagure Orange Road (1984–1988).[21]
The time loop has since become a familiar anime trope.[16] Other popular Japanese works that use the time loop concept includeHiroyuki Kanno's science fictionvisual novelYU-NO: A Girl Who Chants Love at the Bound of this World (1996),[22] thevisual novel and anime franchiseHigurashi When They Cry (2002), thelight novel and anime franchiseHaruhi Suzumiya (2003), Mamoru Oshii'sJapanese cyberpunk anime filmGhost in the Shell 2: Innocence (2004),Hiroshi Sakurazaka'ssci-fi light novelAll You Need is Kill (2004) which was adapted into the Hollywood filmEdge of Tomorrow (2014) starringTom Cruise,[21] and the sci-fi visual novel and anime franchiseSteins;Gate (2009).[23]
Stories with time loops commonly center on the character learning from each successive loop through time.[1] Jeremy Douglass,Janet Murray,Noah Falstein and others compare time loops with video games and other interactive media, where a character in a loop learns about their environment more and more with each passing loop, and the loop ends with complete mastery of the character's environment.[24] Shaila Garcia-Catalán et al. provide a similar analysis, saying that the usual way for the protagonist out of a time loop is acquiring knowledge, using retained memories to progress and eventually exit the loop. The time loop is then a problem-solving process, and the narrative becomes akin to an interactive puzzle.[25]
The presentation of a time loop as a puzzle has subsequently led to video games that are centered on the time loop mechanic, giving the player the ability to learn and figure out the rules themselves. Games likeThe Legend of Zelda: Majora's Mask,Minit,The Sexy Brutale,Outer Wilds,12 Minutes,Returnal andDeathloop were all designed to allow the player to figure out the loop's sequences of events and then navigate their character through a loop a final time to successfully complete the game. According to Raul Rubio, the CEO of Tequila Works that createdThe Sexy Brutale, "Time loops allow players to train to get better at the game, faster, smarter, by experimenting from a fixed starting situation, and seeing what it works to move 'forward' within the loop and adding something else to that structure to build a solid process."[26]