Inscience fiction, atime viewer,temporal viewer, orchronoscope is a device that allows another point in time to be observed.[1] The concept has appeared since the late 19th century, constituting a significant yet relatively obscure subgenre oftime travel fiction and appearing in various media including literature, cinema, and television. Stories usually explain the technology by referencing cutting-edge science, though sometimes invoking thesupernatural instead. Most commonly only the past can be observed, though occasionally time viewers capable of showing the future appear; these devices are sometimes limited in terms of what information about the future can be obtained. Other variations on the concept include being able to listen to the past but not view it.
One reason authors may choose to write about time viewers rather thantime machines is to circumvent the issue oftemporal paradoxes. Recurring applications include studying history, solving crimes, and entertainment in the form of displaying historic events to an audience. Because the past includes events as recently as the previous second, privacy may be compromised by such devices; several stories explore the implications thereof. Other stories examine the effects of being observed by onlookers further into the future. An unanticipated influence on past events is a common motif in stories about time viewers, and exploiting this side-effect appears in some stories.
In its most basic form, a time viewer is a device that only allows the observation of the past.[2]: 97 Unlike with atime machine, the user is not transported from one moment in time to another.[3][4] Under the strictest definition it cannot alter the past;[2]: 97 [3] however, the unexpected discovery that the device does indeed affect the past is a common motif.[2]: 99 [3] Variations on the concept where the future rather than the past is observed are more uncommon but nevertheless appear in multiple works.[3][5]: 128 Another variation involves listening to the past rather than viewing it.[2]: 97–98 [3]
In-universe justifications for the ability to observe the past vary, typically corresponding to contemporary scientific developments;[2]: 98 time viewers exploit impressions on theaether in the 1926 novelThe Vicarion byGardner Hunting,[6]: 58 exoticneutrino properties in the 1956 short story "The Dead Past" byIsaac Asimov,[2]: 104–105 andwormholes in the 2000 novelThe Light of Other Days byStephen Baxter andArthur C. Clarke.[7]: 158–159 A common explanation involves the finitespeed of light and astronomical distances; this method appears in the 1935 short story "The Space Lens" byDonald A. Wollheim, among others.[3] A variation that appears in the 1966 short story "Light of Other Days" byBob Shaw (later included in the 1972fix-up novelOther Days, Other Eyes) is usingslow glass whose highrefractive index means light takes years to pass through it.[2]: 105 [5]: 127–128 [8]: 100–101 Supernatural explanations also occur in works like the 1925 short story "A View From a Hill" byM. R. James, where a pair of binoculars are enchanted to show the past, and the 1976 short story "Balsamo's Mirror" byL. Sprague de Camp, where the titular mirror allows a present-day person to view the world through the eyes of one from the past.[2]: 100 [8]: 100
The earliest known example of a fully fledged time viewer in fiction appears in the 1882 short story "L'historioscope" byEugène Mouton in the form of an electrical telescope, though it was prefigured by a couple of proto-variations on the concept;[3][8]: 100 [9][10] in the 1872 workRecits de l'infini (which later turned into the 1887 novelLumen) byCamille Flammarion a spirit accomplishes the same effect by travellingfaster than light, and the titular device in the 1873 short story "The Automaton Ear" byFlorence McLandburgh enables listening to the past.[3][8]: 100–101 [11]: 251
In film, the first time viewer appeared in the 1918 filmThe Ghost of Slumber Mountain.[3] The concept has appeared regularly in works of fiction ever since, creating a sub-genre withintime travel fiction, but remained comparatively obscure.[2]: 97 [6]: 57–58 [7]: 71 [12]: 532–533
Science fiction authorStephen Baxter identifies several different ways time viewers are used in fiction. The most basic premise is of the time viewer as simply a "neat gadget", with a common variation being something going wrong, typically the past being unintentionally altered. Changing the past on purpose is another recurring application. According to Baxter, the wider implications of the existence of time viewers are sometimes explored inhard science fiction with aPEST (political, economic, social, and technical) analysis.[2]: 98–99, 101
Several authors consider time viewers to be inherently more plausible than time machines. Science fiction authorDamien Broderick says that "using a time viewer is in essence no more absurd than watching a movie made 50 years ago" since the past cannot be affected by it.[7]: 71 Baxter similarly says that time viewers are more extrapolation than fantasy, comparing them toarchaeological research.[2]: 97 For this reason, science writerPaul J. Nahin and physicistStephen Webb say that a benefit for writers is being able to write time travel stories without needing to consider the possibility oftime paradoxes;[5]: 128 [6]: 57–58 Nahin nevertheless notes that interacting with the past via a time machine, or even affecting it, does not necessarily cause paradoxes.[6]: 57
Time viewers are sometimes used to observe moments in history that are similarly popular destinations fortime travel in fiction, one example being thecrucifixion of Jesus in the 1904 novelAround a Distant Star byJean Delaire [Wikidata].[12]: 534 [13] In the 1956 short story "The Dead Past" byIsaac Asimov, a historian is excited to use a time viewer to studyancient Carthage, only to find out that the device is limited to viewing the most recent 120 years,[5]: 127 and a historian uses a time viewer to read the contents of theLibrary of Alexandria in the 1980 short story "One Time in Alexandria" byDonald Franson.[14]: 283
In the 1938–1939Trumpets from Oblivion series byHenry Bedford-Jones, a time viewer allows scientists to discover the explanations for various myths,[3][15] and two war veterans use a time viewer to create historical films in order to dispel public misconceptions about theAmerican Revolution and theAmerican Civil War in the 1947 novelette "E for Effort" byT. L. Sherred.[2]: 103 [5]: 127 Revealing the truth about historical events also appears in the 1953 novelChildhood's End byArthur C. Clarke, wherealien invaders show humanity that our religions are false.[2]: 102–103
Astronomy is similarly studied in the 1969 novelMacroscope byPiers Anthony and the 1999 short story "Hatching the Phoenix" byFrederik Pohl. In the former theformation of the Solar System is studied, while in the latter observations are made of a world that has since been destroyed by a supernova.[3] Scientists in the 2000 novelThe Light of Other Days byStephen Baxter and Arthur C. Clarke use time viewer technology to study the entirehistory of life on Earth.[7]: 160
An early instance of a time viewer being used to solve crimes is the 1926 novelThe Vicarion byGardner Hunting, as events leading up to a crime can be uncovered in reverse after the fact.[2]: 101–102 [3] Later examples include the 1948 short story "Private Eye" byHenry Kuttner andC. L. Moore (writing jointly as "Lewis Padgett"), which revolves around a man planning a murder in such a way that the use of a time viewer by the authorities would not reveal his guilt,[2]: 103–104 and the 2006 filmDéjà Vu, where the device shows events with a four-day delay which cannot be adjusted and there is consequently only one opportunity to view any given event.[3][16]
The 1926 novelThe Vicarion by Gardner Hunting is an early example of time viewers being used for entertainment;[3] in the story, moments from history are shown in movie theaters to great public interest. Baxter compares the in-story effects on society, where "mass addiction to this vibrant spectacle quickly overtakes the public", to the later real-world advent of thetelevision.[2]: 101–102 This theme recurs in the 1947 novelette "E for Effort" by T. L. Sherred, though in that story the public is unaware that the films are not conventional movie productions.[5]: 127
A number of works explore the implications of being capable of remotely viewing the recent past—potentially as recent as less than a second ago—onprivacy.[2]: 101–102, 104–105 [3][5]: 127–128 [17]: 266 In the 1956 short story "The Dead Past" by Isaac Asimov, its use is suppressed by the government for this reason.[2]: 104–105 [5]: 127 In the 1972fix-up novelOther Days, Other Eyes byBob Shaw, particles of theslow glass that captures images are spread all over to enablemass surveillance.[3] The 1976 short story "I See You" byDamon Knight posits that the complete loss of privacy resulting from universal access to a time viewer would usher in autopia free from deceit and embarrassment.[2]: 104 [3]
Espionage applications appeared early; in the 1926 short story "The Time Eliminator" by pseudonymous author "Kaw", the United States government uses a time viewer to spy on a meeting of foreign leaders.[2]: 101 [3] The realization that it can be put to this use triggers war to ensure that it does not in the 1947 novelette "E for Effort" by T. L. Sherred.[2]: 103 [3]
The implication that just as we are watching the past, people in the future are surely watching us is explored in the 1951 short story "Operation Peep" byJohn Wyndham. In order to regain privacy, people eventually resort to shining bright lights to effectively blind the future onlookers.[2]: 102 In the 1953 short story "The Parasite" by Arthur C. Clarke, the realization that he is constantly being watched by a future being eventually drives a man to suicide.[2]: 102 The intensity of observation from the future is measured in the 1981 short story "The Final Days" byDavid Langford to gauge an individual's importance to the world of the future.[3]
Several stories reveal that the time viewer can not only observe the past but influence it.[2]: 99 In the 1951 short story "The Biography Project" byH. L. Gold, being constantly watched drivesIsaac Newton insane.[2]: 99 In thesatirical 1948 short story "The Brooklyn Project" byWilliam Tenn, the scientists in charge insist that the past is immutable even as they and their surroundings undergo drastic changes, because from their new perspective those alterations have always been in place.[2]: 99 [18]: 205 [19]
In some stories, the past is changed intentionally.[2]: 99 Humorous depictions include the 1972 short story "The Greatest Television Show on Earth" byJ. G. Ballard, where a TV company hires additional people as soldiers to make theBattle of Waterloo live up to viewers' expectations, and the 1967 novelThe Technicolor Time Machine byHarry Harrison, which implies that theViking settlement ofVinland only happened because Hollywood wanted to make a movie about it.[2]: 99 A more serious treatment appears in the 1996 novelPastwatch: The Redemption of Christopher Columbus byOrson Scott Card:[2]: 99 after discovering that the past has previously been tampered with, a team of future scientists seek to undo the harm caused byChristopher Columbus'svoyages to theNew World, even though it would mean their timeline would be obliterated.[20]: 187–188 [21]: 258–261 [22]: 54
Rarely, time viewers may be depicted as allowing observation of the future rather than the past.[3][5]: 128 Stephen Webb argues that viewing the future has more in common withfantasy andfortune-telling than withscience fiction,[5]: 128 andDavid Langford notes inThe Encyclopedia of Science Fiction that the possibility of viewing the future has implications for the question offree will versusdeterminism.[3]
Devices capable of viewing the future have been portrayed in various ways. In the 1922 short story "The Prophetic Camera" byLance Sieveking, the titular camera can take pictures an adjustable amount of time into the future,[3][23]: 685 while in the 1960The Twilight Zone episode "A Most Unusual Camera" the device only has a reach of five minutes into the future.[6]: 60 In the 1955 novelThe Pleasures of a Futuroscope byLord Dunsany, the device reveals a futurenuclear holocaust.[3][24] In the 1924 short filmThe Fugitive Futurist a gambler is offered to buy a future-viewing device which he intends to use to find out which horses to bet on, though the device turns out to be fake.[3][25] The chronoscope in the 1936 short story "Elimination" byJohn W. Campbell can show both the past and all possible futures.[6]: 60
Future-viewing devices are occasionally limited in what they are able to show rather than being general-purpose.[3] One example is the device in the 1939 short story "Life-Line" byRobert A. Heinlein which can determine an individual's moment of death by measuring the reflection from the future end of that person'sworld line; a similar device that reveals the manner but not time of death appears in the 2010 anthologyMachine of Death: A Collection of Stories About People Who Know How They Will Die byRyan North,Matthew Bennardo, andDavid Malki.[3][5]: 128 Another is the instantaneous "Dirac communicator" introduced in the 1954 short story "Beep" byJames Blish which due to thelack of a speed-of-light delay can send messages to the past.[3][26]: 148–150 [27]
"The Brooklyn Project" however is one of my favorite time travel stories. Despite warnings that changes wrought in the past would be undetectable because people in the present would assume they had always been the case, an experiment leads to the replacement of humanity by intelligent amoebas.
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