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Multiple realities
(covers information from several alternate timelines)
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This page contains information regarding Star Trek: Picard, and thus may contain spoilers.

A Zahl colony fired upon by the Krenim weapon ship...

...and the alternate timeline where the colony never existed

For the alternate timeline created by the destruction of the USS Kelvin, please see alternate reality.

Alternate timelines were altered versions of the timeline. Unlike parallel universes, alternate timelines often did not seem to diverge from the universe, but instead rewrote history to the point of wiping out the original timeline. However, alternate timelines did sometimes co-exist as alternate realities. (ENT: "Storm Front"; TOS: "The City on the Edge of Forever"; TNG: "Yesterday's Enterprise"; DS9: "Past Tense, Part I", "Past Tense, Part II"; VOY: "Non Sequitur", "Year of Hell", "Year of Hell, Part II", "Relativity", "Timeless"; Star Trek; PIC: "Penance")

Alternate timeline creation

There were several methods of temporal manipulation that could create an alternate timeline:

A display featuring several alternate timelines created by the Krenim

As a rule, Starfleet officers were forbidden to cause changes in the timeline or to share their knowledge of future events by the Temporal Prime Directive. (VOY: "Shattered") The Department of Temporal Investigations was tasked to ensure that time travel events did not contaminate the timeline. (DS9: "Trials and Tribble-ations") By the 28th century, changing the timeline had become more universally illegal after the Temporal Accord was established. (ENT: "Cold Front") By the 29th century, Starfleet had taken it on as a mission to use time travel as a means of upholding the integrity of the timeline by fixing changes in the past. It was also Starfleet policy by then to integrate different versions of people into one, when several coexisting ones appeared due to paradoxes and time travel. (VOY: "Relativity") By the 32nd century, time travel had been banned outright because the Temporal Wars made it clear that time travelling societies could not be trusted to shun fanatics such as Vosk who felt entitled to alter the timeline regardless of the consequences. (ENT: "Storm Front", "Storm Front, Part II"; DIS: "That Hope Is You, Part 1")

While the prime timeline was usually restored by operatives from the 29th to the 31st centuries, in some cases, the influence of alternate timelines remained as a part of the chain of events in the prime timeline. The crew of the USS Enterprise-E, for instance, would not have learned that they had to travel to the past to convince Zefram Cochrane to make the test warp flight, had they not accidentally witnessed an alternate timeline, where the Borg prevented Humanity's First Contact with the Vulcans and assimilated Earth. (Star Trek: First Contact; VOY: "Relativity") Warnings, temporal incursions and information of the original future were also an integral part of the prime timeline. Such was the case, when Captain Jean-Luc Picard shared his experiences of the future shown to him by Q, to his crew in 2370, causing them to make different life choices that created a new and entirely different timeline of the future. (TNG: "All Good Things...") USS Voyager was rescued and aided by its crew members from the future. In 2375, a transmission from Harry Kim from 2390 averted the crash landing of the Voyager. In 2378, technology and assistance from Admiral Janeway from 2404 saved the ship from a longer disastrous journey through the Delta and Beta Quadrants. (VOY: "Timeless", "Endgame")

Alternate realities

Different versions of a timeline also sometimes coexist as parallel universes. Most active temporal anomalies allow interaction between two different alternate timelines for a moment, making them parallel realities in relation to one another. (ENT: "Shockwave"; TOS: "The City on the Edge of Forever"; TNG: "Yesterday's Enterprise"; Star Trek)

Borg Queens had transtemporal awareness, which granted them knowledge bridging into other alternate timelines and realities, described as hearing "echoes" of alternate versions of themselves that co-existed with their own. (PIC: "Penance")

The Narada appearing out of a black hole, creating an alternate reality

The writers of Star Trek, Alex Kurtzman and Roberto Orci, were asked about the implications of the new alternate reality that was introduced in the film in an interview. They explained the new reality runs parallel to the prime reality as a new quantum reality, as the concept was explained by Data in the episode TNG: "Parallels". [1] The continued existence of the prime reality was later confirmed with ST: "Calypso" and Star Trek: Picard.
  • In 2370, Q allowed Picard to shift his consciousness between three different timeframes, one in the past, one in the present and one in the future from Picard's point of view, in order for him to create an anti-time eruption. The eruption was linking these timelines together, and when it collapsed the timelines ceased to exist. (TNG: "All Good Things...")
Several statements in Star Trek suggest that many alternate timelines co-exist. It was stated in ENT: "Azati Prime" that the Sphere-Builders had technology that allowed them to examine alternate timelines. In the episode, Daniels even had the technology to take Archer to the future of an alternate timeline. The time vortex was called a focal point of "all timelines" in TAS: "Yesteryear".
By the 32nd century, the existence of alternate timelines is treated as fact: Kovich demonstrates knowledge of both the mirror universe (DIS: "Die Trying") and the alternate reality (DIS: "Terra Firma, Part 1"), and references an Interdimensional Displacement Restriction as legally preventing travel between timelines.

Pockets, folds, and fragments

An alternate Earth, assimilated by the Borg after their temporal incursion, seen from the wake of a temporal vortex

  • The race of the alien who took the shape of Cosimo existed in temporal inversion folds of the space-time matrix. The folds were parallel time streams visible as temporal anomalies intersecting the prime reality. Inside the folds, reality remained unaffected by changes in the timeline. It was possible to utilize a fold to exchange one's consciousness with an alternate timeline version of oneself. (VOY: "Non Sequitur")
  • Temporal causality loops create independent fragments of time, inside which the time of the universe repeats itself. From outside the loop, it appears as if anything inside it simply vanished from the space-time continuum. For people inside the loop, the memories from previous loops begin to assert themselves as a sense of déjá vu and eventually as clearer memories. (TNG: "Cause and Effect")

Time continuums

The Devidian time continuum

Within the universe there were also several parallel time continuums occupying the same space but in different times. (TNG: "Time's Arrow")

  • Elysia was a small parallel time continuum that periodically touched the prime universe in the Delta Triangle region. Elysia was described by Devna as a pocket in the garment of time. The collisions between the two alternate universes produced time warp vortexes in the time barrier between the universes, that allowed passage from one side to the other at high warp speed. (TAS: "The Time Trap")

List of alternate timelines

Timeline Timescale Created by Status Appearance
Captain Archer disappears and the United Federation of Planets never forms 2152-31st century Daniels transporting Archer to 31st century Earth Negated when Archer returned to his own time ENT: "Shockwave", "Shockwave, Part II"
The Xindi and Humanity do not engage in hostilities throughout the 2150s 2150s Original timeline Negated when the Sphere-Builders manipulated the Xindi as part of the Temporal Cold War, sparking the Xindi incident ENT: "The Expanse"
The Xindi destroy Earth and all other Human colonies 2153-2165 Original timeline Negated when Archer's interspatial parasites were erased from history during the Battle of Ceti Alpha V ENT: "Twilight"
The Sphere-Builders invade the Milky Way Galaxy, but are defeated at the Battle of Procyon V 26th century Unknown, possibly original timeline Unknown, possibly negated by the destruction of the Delphic Expanse spheres in 2154 ENT: "Azati Prime"
Enterprise NX-01 remains in the Delphic Expanse for 117 years 2037-2154 Temporal displacement of Enterprise by a subspace corridor Unknown, possibly negated when Enterprise avoided time traveling ENT: ""
Temporal War 1916-31st century Unknown, caused by a predestination paradox Negated when Enterprise prevented Vosk from returning to the 29th century ENT: "Storm Front", "Storm Front, Part II"
The USS Discovery is trapped in a time loop lasting only thirty minutes in each iteration, in which most instances result in the destruction of the Discovery, during the Federation-Klingon War. 2256 Harcourt Fenton Mudd utilized a time crystal and distracted the crew with a gormagander so that he could explore the ship's technologies and intelligence unhindered before he delivered the Discovery to the Klingons Negated when Paul Stamets recruited Michael Burnham and Ash Tyler to trick Mudd into ending the time loop prematurely DIS: "Magic to Make the Sanest Man Go Mad"
All sentient life in the galaxy is destroyed by Control, which has malfunctioned due to the inherent contradiction in destroying life to protect life and having become sentient 2257-3186 Original timeline Negated due to multiple incursions by Gabrielle Burnham, followed by the crew of the Discovery intentionally traveling to the far future in order to prevent the rogue AI from obtaining data it required to become sentient DIS: "If Memory Serves", "Perpetual Infinity", "Such Sweet Sorrow", "Such Sweet Sorrow, Part 2"
John Christopher, a staff sergeant and the Omaha installation personal encounter the USS Enterprise crew July 1969 Actions of the temporally-displaced Enterprise crew Negated when John Christoper and the sergeant were returned to Earth at a point before they encountered the Enterprise TOS: "Tomorrow is Yesterday"
Nazi Germany conquers Earth and the United Federation of Planets and Starfleet never form 1930-2267 Leonard McCoy preventing Edith Keeler's death Negated when James T. Kirk stopped McCoy from saving Keeler TOS: "The City on the Edge of Forever"
Spock dies at seven 2237-2269 Captain Kirk and Commander Spock Negated by Spock's future self TAS: "Yesteryear"
The USS Enterprise-D is destroyed by an energy vortex 2365 Unknown, possibly the original timeline Negated when Jean-Luc Picard prevented the Enterprise's destruction TNG: "Time Squared"
Mid-24th century Federation-Klingon War 2344-2366 Temporal displacement of the USS Enterprise-C Negated when the Enterprise-C returned to the Battle of Narendra III TNG: "Yesterday's Enterprise"
Thomas Halloway becomes captain of the Enterprise-D instead of Jean-Luc Picard 2327-2369 Q causing Picard to prevent a fight against a group of Nausicaans Negated when Picard returned to 2327 and started the fight TNG: "Tapestry"
The Enterprise-D is destroyed by a warp core breach 2369 Quantum singularity lifeforms Negated when Picard, Data, Deanna Troi, and Geordi La Forge reversed time to a point just before the breach occurred TNG: "Timescape"
Alexander Rozhenko never becomes a warrior and his father is murdered on the floor of the Klingon High Council 2370-2410 Original timeline Negated when Alexander's future self convinced his past self to become a warrior TNG: "Firstborn"
An anti-time eruption forms in the Devron system and prevents the formation of life on Earth 3.5 billion years ago, 2363-2364, 2370-2371, and 2395 Repeated temporal displacement of Picard by Q Negated when Picard sealed the eruption with a static warp shell TNG: "All Good Things..."
The Veridian system is destroyed by Tolian Soran 2371 Original timeline Negated when Picard prevented the system's destruction Star Trek Generations
Gabriel Bell dies and the United Federation of Planets and Starfleet never form 2024-2371 Benjamin Sisko and Julian Bashir causing Bell's death Negated when Sisko replaced Bell's role in history DS9: "Past Tense, Part I", "Past Tense, Part II"
Kathryn Janeway dies on Makull's homeworld in a polaric ion explosion 2371 Unknown, caused by a predestination paradox Negated when Janeway prevented the explosion VOY: "Time and Again"
Miles O'Brien dies from a high-energy laser 2371 Unknown, possibly the original timeline Negated by O'Brien learning of his death prematurely DS9: "Visionary"
Miles O'Brien dies from radiation poisoning 2371 Unknown, possibly the original timeline Negated by O'Brien warning the past Bashir of his death DS9: "Visionary"
Deep Space 9 and the Bajoran wormhole are destroyed by a Romulan Warbird 2371 Unknown, possibly the original timeline Negated by O'Brien warning Sisko of the attack 3.5 hours before it occurred DS9: "Visionary"
Daniel Byrd joins the USS Voyager instead of Harry Kim 2371 Temporal inversion fold Negated when Kim returned through the time stream VOY: "Non Sequitur"
Second Federation-Klingon hostility 2372-2450 Temporal displacement of Benjamin Sisko by an energy discharge from the Defiant's warp core Negated when Benjamin Sisko returned to the past and dodged the discharge DS9: "The Visitor"
The Call of the Prophets is not finished 22nd century-2372 Temporal displacement of Akorem Laan by the Bajoran wormhole Partially negated when the Prophets returned Akorem Laan to his proper time period DS9: "Accession"
Henry Starling founds Chronowerx Industries and destroys the Sol system in a temporal explosion 1967-29th century Unknown; caused by a predestination paradox Negated when Voyager destroyed the Aeon before it arrived in the future VOY: "Future's End", "Future's End, Part II"
The Borg Collective assimilates Earth 2063-2373 Borg Queen's sphere Negated when the USS Enterprise-E defeated the Borg in the past Star Trek: First Contact
First Year of Hell 2373-2379 Original timeline Presumed negated by Tuvok due to Kes' actions in 2373 VOY: "Before and After"
The USS Defiant crashes on Gaia and colonizes the planet 22nd century-2373 Temporal displacement of the Defiant Negated when Odo's older self altered the Defiant's flight plan DS9: "Children of Time"
Second Year of Hell 2174-2374 Multiple temporal incursions by Annorax's weapon ship Negated when Kathryn Janeway caused the weapon ship to erase itself from history VOY: "Year of Hell", "Year of Hell, Part II"
Molly O'Brien is stranded on Golana for ten years 21st century Time portal Negated when Molly's younger self went back to 2374 DS9: "Time's Orphan"
Voyager crashes on an L-class icy planet upon emerging from a quantum slipstream 2375-2390 Original timeline Negated when Harry Kim caused Voyager to emerge from the slipstream 50,000 light years from Earth VOY: "Timeless"
Voyager is destroyed by a temporal disruptor 2370-2375 Captain Braxton planting the disruptor aboard Voyager Negated when Janeway prevented Braxton from planting the device on Voyager VOY: "Relativity"
Kes murders B'Elanna Torres and time travels to 2371 2376 Original timeline Negated when Janeway and Tuvok took precautions to prevent history from repeating itself VOY: "Fury"
Voyager is fractured into multiple different time periods in 2377 2371, 2372, 2373, 2374, 2375, 2377, and 2394 Chronokinetic surge Negated when Chakotay reintegrated Voyager into one time period and prevented the surge from fracturing Voyager VOY: "Shattered"
Voyager returns to Earth in 2394 2378-2404 Original timeline Negated when Admiral Janeway returned Voyager home in 2378 VOY: "Endgame"
Alternate reality 2233 and beyond Nero's appearance in 2233 Intact; coexists with the prime timeline as a parallel universe at least as late as 2379 Star Trek, Star Trek Into Darkness, and Star Trek Beyond
Philippa Georgiou attempts to reform the Terran Empire and stop Gabriel Lorca's coup, but she and Michael Burnham kill each other 2250s Morality test by the Guardian of Forever Unknown; may have only existed for the purposes of the morality test, but may also be still intact due to the Guardian of Forever's comment about how an alternate version of Georgiou "may not be feeling so hot". DIS: "Terra Firma, Part 1", "Terra Firma, Part 2"
The xenophobic, authoritarian Confederation of Earth rules much of the galaxy, having conquered the Cardassians, Klingons, Romulans, Vulcans, Andorians, and Borg, amongst others. 2024-2401 Q interferes with the Europa Mission, causing humanity to turn to Dr. Adam Soong instead Negated when Jean-Luc Picard, Seven of Nine, Cristóbal Rios, Agnes Jurati, Raffaela Musiker, the Borg Queen and Tallinn ensure Renée Picard's survival and the launch of the mission. Star Trek: Picard Season 2
The USS Stargazer is self-destructed by Jean-Luc Picard. 2401 Original timeline Negated when Picard, after returning from 2024 to moments before the explosion, realized that the Borg Queen was the same one that had merged with Dr. Agnes Jurati and thus he halted the auto-destruct. PIC: "The Star Gazer", "Farewell"



Alternate timelines are depicted in the following episodes or films:

Related topics

Background information

The following is a list of episodes involving alternate timelines.

Episode Time Periods Cause Effects
"The City on the Edge of Forever" 1930-2267 Edith Keeler's death averted by McCoy Nazi Germany lasts beyond 1945, United Federation of Planets does not exist
"Yesteryear" 2269, 2237 Death of Spock as a child Amanda Grayson has died, Thelin became USS Enterprise's first officer
"Yesterday's Enterprise" 2366 USS Enterprise-C went through a temporal rift in 2344 Federation embroiled in a long war with the Klingons
  • By 2366, 22 years of war have raged between Klingons and the Federation, with the death toll in the billions. At this point, the war is going badly for the Federation, and a surrender seems the most likely outcome.
  • The USS Enterprise, while retaining her exterior, has been fitted as a battleship, with less luxury than the prime timeline USS Enterprise.
  • The Enterprise has been fighting the Klingons for the past four years, and many, if not all, of the missions the "prime" Enterprise undertook have not been undertaken by this Enterprise.
  • Related to the above, Natasha Yar is still alive in 2366.
  • The Enterprise has no children on board as a result of the war.
  • Wesley Crusher is a full ensign in 2366, which implies either an earlier acceptance into Starfleet Academy or, as seems more likely in this timeline, that he was drafted into the military.
"Past Tense, Part I", "Past Tense, Part II" 2024, 2048, 2371 Gabriel Bell dies Federation does not exist, Romulans encroach on Alpha Centauri
"Accession" 9174 (Bajoran year) in the 22nd century (Earth calendar) Akorem Laan disappears from history, entering the Bajoran wormhole Akorem doesn't complete his poem The Call of the Prophets
"Non Sequitur" 2372 Timestream Harry Kim did not join USS Voyager, Daniel Byrd joined instead
"Year of Hell", "Year of Hell, Part II" 2374 Krenim weapon ship Numerous incursions
"Twilight" 2153-2165 Interspatial parasites Archer removed as captain of Enterprise NX-01, Xindi destruction of Earth and Human colonies
"Storm Front", "Storm Front, Part II" 1916-1944 Multiple spatial incursions; Na'kuhl violate Temporal Accord; Temporal Cold War goes hot Vladimir Lenin assassinated by unknown temporal agent and not replaced; Union of Soviet Socialist Republics never founded; Nazi Germany able to focus on West, resulting in an alternate World War II where, with the help of the Na'kuhl, Germany successfully invades the United States of America
Star Trek Generations 2371 Tolian Soran destroys the Veridian system Civilization on Veridian IV wiped out; USS Enterprise crew killed; Soran enters the Nexus
Star Trek: First Contact 2063 The Borg assimilate Earth Humans never achieve warp drive; Federation never founded; Borg space in the Alpha Quadrant
Star Trek, Star Trek Into Darkness, Star Trek Beyond 2233 onward Accidental temporal incursion by the Narada, whose captain proceeds to enact a revenge plot that irrevocably changes the timeline Among other changes:
USS Kelvin destroyed, causing James T. Kirk to be born early and left without a father; Kirk joins Starfleet at a later date; Vulcan destroyed in 2258, leaving the Vulcans critically endangered; Earth nearly destroyed; Kirk given command of the USS Enterprise several years early; Christopher Pike promoted to admiral

Militarization conspiracy; Khan Noonien Singh and his followers awakened early; Christopher Pike killed in 2259; Enterprise embarks on her five-year mission several years early
Enterprise destroyed in 2263 rather than 2285; USS Franklin mystery solved; USS Enterprise-A launched in 2263 rather than 2286


According to the Star Trek: Myriad Universes story "Places of Exile" by Christopher L. Bennett in the 2008 novel of the series, Infinity's Prism, the concept of quantum realities is synonymous with all types of alternate timelines. According to the 2008 novel Fearful Symmetry by Olivia Woods, the mirror universe is also a parallel quantum universe, further suggesting that even trans-dimensional realms are alternate timelines.

The Star Trek: Department of Temporal Investigations novel Watching the Clock goes into detail about how and why some forms of time travel create parallel alternate realities and others lead to the overwriting of the same timeline. According to the novel, the only way one timeline could replace another is if they coexisted side by side from the moment of their divergence and were merged together again at a later point. Timelines diverge when they shift sufficiently out of phase to become non-interacting, but it is not impossible for them to interfere again at a later point in time. If they did become entangled as a single system, quantum information theory demands that only one of the two conflicting sets of information survive, as quantum history has to be self-consistent. After the merge, it would be as if one timeline suddenly transformed into another. The previous events would still have occurred, but they would no longer be remembered, as the information would have been destroyed. Two different timelines coming back into phase would violate entropy, so there needs to be some kind of force acting to merge them back together.

The game Star Trek: Armada features the USS Premonition (β), a starship that came from an alternate future where the Borg controlled most of the Alpha Quadrant. Captain Thaddius Deming of the Premonition hoped to warn the Federation of a coming Borg invasion in time to prevent the Borg victory. With the help of Captain Jean-Luc Picard of the USS Enterprise-E, and after making two further temporal incursions, the Premonition's mission was a success and she returned back to the future.

The Star Trek: Coda novels establish the material seen in the relaunch novels for the series Star Trek: The Next Generation, Star Trek: Deep Space Nine and Star Trek: Voyager as being set within a quantum reality known as the First Splinter timeline (β) in order to reconcile the differences resulting from the creation of series such as Star Trek: Picard and Star Trek: Prodigy.

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