Time travel

The HMS Bounty slingshots around Sol

"Science Vulcan Directorate has determined that time travel is… not fair."

– T'Pol, wearily speaking to Captain Jonathan Archer who is communicating from the 31st century, 2152 ("Shockwave, Part II")

Time travel is having the ability to or the act of travel forward or backward in time, thus breaking the seemingly irreversible flow of time. The study of this phenomenon is one of the focuses of temporal mechanics. Alterations to historical events can cause, among other things, alternate timelines and realities.

As late as 2154, time travel was deemed impossible by the Vulcan Science Directorate. (ENT: "Awakening")

The United Federation of Planets had some form of time travel ability since at least 2268. Regulations on time travel were later imposed to prevent alterations from being made to the timeline. (TOS: "Assignment: Earth"; DIS: "Such Sweet Sorrow, Part 2"; DS9: "Past Tense, Part I", "Past Tense, Part II", "Trials and Tribble-ations")

In addition to the Federation, the Borg Collective, Bajorans, and the Klingon Empire were known to have some form of time travel capabilities. (Star Trek: First Contact; DS9: "Trials and Tribble-ations", "Wrongs Darker Than Death or Night"; DIS: "The Red Angel"; TNG: "Firstborn"; VOY: "Endgame")

History

Overview

Historical research in 2268 suggested the Federation was capable of controlled time travel and used this ability at the very least for research purposes. (TOS: "Assignment: Earth")

As of 2378, at least forty different instances of some form of time travel had been noted in Federation records. Technologically speaking, the Federation's capabilities concerning time travel, for the most part, remained unclear.

In the 25th century, time travel was mostly possible but still risky. (TNG: "Firstborn")

As of the 26th century, historians and anthropologists used time-pods to travel through time to observe historical events. (TNG: "A Matter Of Time")

In the 29th century, the Federation had the ability to scan time as well as space, and travel back (and presumably forward) in time to attempt to fix issues and anomalies. (VOY: "Future's End", "Future's End, Part II", "Relativity")

In the 31st century, time travel was commonplace. Federation temporal agents from this time became involved in a Temporal Cold War, which eventually led to temporal wars. After these wars, time travel was banned and the technology used to travel in time was destroyed. (ENT: "Shockwave, Part II"; DIS: "That Hope Is You, Part 1")

Events

Crewman Daniels, a temporal agent from the 31st century, showed Jonathan Archer a group of time-traveling anthropologists from 2769 observing the building of the pyramids of Giza. (ENT: "Cold Front")

In the 2230s, Section 31 created a special Red Angel time-traveling suit in response to Klingon time-traveling studies. This suit would use a special time crystal that created micro-wormholes to travel through time. A Klingon attack forced its test pilot, Gabrielle Burnham, to use it, bouncing throughout time. Section 31 thought the technology destroyed. (DIS: "The Red Angel", "Perpetual Infinity", "Through the Valley of Shadows")

Time crystal-related technology was available outside of Federation oversight by late 2256, when Harry Mudd procured a time crystal-powered device that allowed him to rob a Betazoid bank and commandeer the USS Discovery, while repeatedly (and creatively) murdering her captain, Gabriel Lorca. (DIS: "Magic to Make the Sanest Man Go Mad")

The Discovery, after being transported to the mirror universe in late 2256 or early 2257 due to Captain Gabriel Lorca's machinations, returned to her original universe nine months later due to difficulties navigating the mycelial network. Her crew ended the Federation-Klingon War shortly thereafter. (DIS: "What's Past Is Prologue", "The War Without, The War Within", "Will You Take My Hand?")

In 2258, the Discovery was transported via a time crystal-generated wormhole to 3188 in order to prevent Control from becoming sentient and destroying all life in the galaxy. (DIS: "Such Sweet Sorrow, Part 2")

Captain Christopher Pike was transported via time crystal by his own future self to 2266 to witness the terrible future that would occur if Pike attempted to change his own fate. (SNW: "A Quality of Mercy")

The USS Enterprise first experienced time travel in 2266, when an emergency cold start of its warp drive slingshot the ship and its crew seventy-one hours into the past. (TOS: "The Naked Time")

In 2267, after an encounter with a black star, the Enterprise was hurled three hundred years into the past. Eventually, the Enterprise's science officer Spock devised a method for returning the Enterprise back to its original period. (TOS: "Tomorrow is Yesterday")

Though other instances of time travel had been noted, this appears to be the first instance of controlled time travel by the Federation.

Later that year, officers Kirk, Spock, and McCoy traveled to Earth's early 20th century and back via the Guardian of Forever. (TOS: "The City on the Edge of Forever")

Sometime in 2268, the Enterprise traveled back in time, using the light-speed breakaway factor, to 1968, on a historical research mission. (TOS: "Assignment: Earth")

Time warp effects experienced by Kirk and crew

In 2286, Admiral James T. Kirk and his senior staff took a stolen Klingon Bird-of-Prey back in time to the year 1986, to retrieve a pair of humpback whales, a species which was extinct by 2286, to save Earth from destruction by an alien probe. (Star Trek IV: The Voyage Home)

According to the film's script, the subjective time travel sequence shown was created by ILM.

Of that sequence, the following was described:
"We are inside Kirk's MIND as we see a series of hypnotic dream images floating up from Kirk's subconscious; undulating figures which float toward us and pass… Liquid faces… amorphous figures… images of Kirk's shipmates in semi-transparent ghostly shapes -- aging and regressing. Kirk's image of himself running toward himself…underwater looking up at a sunlight-dappled surface… gently waving strands of reeds at an abstract shoreline… disembodied voices, sounds and music add to the hypnotic effect. And then… A WHOOSHING ROAR begins to mount and grow louder until it climaxes with a terrible BANG!"

In 2371, Captains Jean-Luc Picard and James T. Kirk used the Nexus as a means of controlled time travel, going to just before the destruction of the Veridian star, which Picard intended to save. (Picard arrived at the Nexus from just after the destruction of said star, whereas Kirk arrived from some seventy-eight years before.) (Star Trek Generations)

Data, unknowingly at first, traveled back in time to Earth 1893 while investigating an alien species that was later found to be ingesting the neural energy from Humans of that time period. The aliens acquired their sustenance by traveling through a portal back to that time and place from Devidia II, and were able to shield their presence from outsiders by being slightly out of temporal sync with everyone else, disguising their presence further by taking advantage of a local cholera outbreak. Picard, Riker, Crusher, La Forge, and Troi soon followed to retrieve Data and assess the situation. As the Enterprise crewmembers covertly endeavored to stop the aliens and return to their own time, Samuel Clemens was suspicious of them, and was accidentally sent to the 24th century with the Enterprise crewmembers (except Picard) when they used the alien portal to return to their own time. Clemens managed to go back through the portal and retrieve Picard, returning each man to his own time period before the Enterprise destroyed the aliens and their portal. (TNG: "Time's Arrow", "Time's Arrow, Part II")

Twice, Q took Picard back in time. The first time was when Picard lay dying in a starbase medical facility during a replacement of a defective artificial heart that he had received as a result of a Nausicaan knife being stabbed through his heart immediately after Picard had graduated from Starfleet Academy on Starbase Earhart. (TNG: "Tapestry") The other example was to the beginning of life on Earth, and also back and forth in Picard's lifetime. (TNG: "All Good Things...")

During a transporter accident above Earth caused by chroniton particles being accidentally fused to the hull of the USS Defiant, Benjamin Sisko, Julian Bashir, and Jadzia Dax were sent back in time to the early-21st century, just before the Bell Riots. This caused the Federation and Starfleet to vanish in the present, after the time travelers' interference led to the death of Gabriel Bell before he would have played a crucial role in history. Only the Defiant was left protected by the chroniton particles. Sisko took on the identity of Gabriel Bell to ensure that he was remembered for saving hostages during the events, and ultimately allowing the Federation to come into being over a century later. (DS9: "Past Tense, Part I")

After becoming infected with delta-series radioisotopes following an accident aboard coupled with the presence of a cloaked Romulan warbird nearby, had the effect of shifting Miles O'Brien forward in time by several hours on multiple occasions. O'Brien's return to the present altered the course of the future events that he witnessed, allowing him to change his own fate. On his final jump into the future, a controlled one to learn what would cause the destruction of the station, O'Brien became too sick to jump back to his present and he was instead replaced by the Miles O'Brien of three and a half hours into the future. (DS9: "Visionary")

While on a trip to Earth to take Nog to Starfleet Academy, Quark, Rom, Nog, and Odo were accidentally propelled back to circa 1950, crashing near Roswell, New Mexico, due to a sabotaged warp core on a ship that had been given to them by Quark's cousin Gaila. They managed to return to their own time using the reaction between kemocite and the radiation of a nuclear explosion on Earth. These events – which included Quark attempting to alter the timeline by selling goods to the United States of America during the Cold War, and the Ferengi subsequently being interrogated on the suspicion that they were secretly planning an invasion – were kept secret from the public on Earth at the time. (DS9: "Little Green Men")

Akorem Laan, a poet and seer from Bajor's past (whom history had recorded had mysteriously disappeared) was sent to the future by the Prophets, believing he was the Emissary of the Prophets. Ultimately, Sisko convinced the Prophets to send Laan back into his own period. Laan later went on to finish one of his prophetic poems, which Major Kira remembered as unfinished, after Laan had disappeared. Sisko pointed out that the ending of the poem had appeared in databases, along with new history of his life after his return to Bajor. Although Kira wondered why she could remember the previous timeline if that timeline had been wiped out, Sisko commented that time worked in mysterious ways whenever the Prophets were involved. (DS9: "Accession")

Quinn took the USS Voyager back in time to the Big Bang to hide from Q. (VOY: "Death Wish")

In 2373, the USS Defiant, commanded by Captain Sisko, traveled back in time to 2268 via the Bajoran Orb of Time, in an attempt by Arne Darvin to kill James T. Kirk and change the timeline. The crew of the Defiant stopped Darvin without any notable damage. Major Kira found a way to use the Orb to get the Defiant and its crew back to their own time. (DS9: "Trials and Tribble-ations")

In 2373, around Stardate 50814.2, the Defiant became stuck behind a barrier on a planet in the Gamma Quadrant, where the ship's crew met inhabitants of the planet, who told them they were actually descendants of the Defiant crewmembers themselves and that, in two days, the crew would be sent two hundred years into the past and crash on the planet. With foreknowledge of the crash, the crew surmised that, if they escaped that fate, the timeline would collapse and everything on the planet would cease to exist. A descendant of Jadzia Dax, Yedrin, surmised that it would be possible to save their colony, due to an energy discharge that had hit Major Kira, which had created a subspace doubling effect and, for an instant, created corresponding quantum duplicates of every molecule in her body. By amplifying the doubling effect through modifications to the Defiant, they could make a quantum duplicate of the entire ship, and this second ship would then be the one that would crash on the planet, preserving the original timeline. However, the other Defiant would be able to escape as well. Yedrin, though, had falsified information in his plan, with the intent of making sure that the original (un-duplicated) single Defiant would crash on the planet, thus ensuring that the colony would continue to exist. The Defiant crewmembers ultimately made the decision to sacrifice their ship by flying into the temporal anomaly, in order to save the eight thousand colony members. However, the ship's flight plan was changed, by a version of Odo who lived on the colony, so that it would clear the barrier, the future Odo wanting to save Kira's life. This erased the settlement and all of its inhabitants from the planet. (DS9: "Children of Time")

Kira used the Orb of Time to learn about her mother's life on Terok Nor. Before she began her Orb experience, she was warned not to interfere with the timeline by Sisko. Kira nearly assassinated her own mother and Dukat, but changed her mind at the last moment. The Orb then returned her to the present. (DS9: "Wrongs Darker Than Death or Night")

During a visit to the planet Golana with her family, Molly O'Brien was accidentally sent three hundred years into the past via a time portal created by a long-lost civilization that had once inhabited the planet. She was retrieved by her parents, but was now a teenager reduced to a feral mindset, forcing them to use the portal to send her back. However, their subsequent use of the portal sent the teenage Molly back to shortly after her past self arrived in the past in the first place, allowing her to send her past self back to the present. Shortly after saving the younger Molly, the older Molly ceased to exist, vanishing from existence as the timeline corrected itself. (DS9: "Time's Orphan")

Also in 2373, an encounter with the 29th century timeship Aeon threw Voyager back to 1996, while the Aeon crash-landed in 1967 and was discovered by Henry Starling, who used its future technology to make himself rich. History was corrected when Captain Janeway destroyed the timeship before it could travel to the future and accidentally cause a temporal explosion. Voyager was returned to the correct time by an alternate version of the Aeon from the correct timeline. (VOY: "Future's End", "Future's End, Part II")

An alternate future version of Janeway (from 2404) traveled back to 2378 through the use of a chrono deflector, to bring Voyager home from the Delta Quadrant sixteen years earlier than it had arrived in that alternate future. This future Janeway was killed in the attempt but succeeded in returning Voyager home and even delivered a crippling if not fatal blow to the Borg. (VOY: "Endgame")

In 2381, Ensign Brad Boimler was accidentally sent back to 2259 by the Krulmuth-B portal on Krulmuth-B when fellow ensign Sam Rutherford accidentally activated it with his camera, putting him in the care of Captain Pike and his crew of the Enterprise. Their attempts to return Boimler to the future were complicated by various incidents, including Beckett Mariner throwing herself through the portal, Orion scientists stealing the portal and the need to find a source of horonium to power the portal. (SNW: "Those Old Scientists")

In 2387, Nero and Spock were sent back in time through a red matter black hole which had prevented a supernova from destroying the galaxy (but not before it had destroyed Romulus in the process). Nero was sent back to the past to 2233, inadvertently creating a new spacetime continuum where he destroyed the USS Kelvin. He and his crew then went into hiding for twenty-five years, awaiting Spock's arrival. Spock arrived in Nero's new timeline in 2258. Nero destroyed Vulcan, while Spock watched from Delta Vega. The crew of the USS Enterprise, with the help of James T. Kirk, stopped Nero from destroying Earth. (Star Trek)

In 2401, Q transported Picard, Elnor, Seven of Nine, Agnes Jurati, Cristóbal Rios and Raffaela Musiker into an alternate timeline where Earth was now the Confederation of Earth (PIC: "The Star Gazer", "Penance") due to Q's own meddling in the past. With the help of an alternate Borg Queen, the group used the slingshot effect to travel back in time to 2024 in order to right history. (PIC: "Assimilation") Q later returned the group, minus Rios and Jurati, to 2401 using his own powers at the cost of Q's life due to his weakened state. The group was returned to just moments before they had left, giving them the opportunity to alter their own future slightly. (PIC: "Farewell")

Temporal Cold War and temporal wars

The events of the Temporal Cold War further complicated the understanding of Federation time travel capabilities.

As of the 28th century, a time-traveling faction, represented by a mysterious individual, could only communicate and exchange information and technologies through time, appearing as non-corporeal entities. By the 29th century, this technology was perfected to allow physical travel.

According to a Temporal Enforcement Agent from the 31st century named "Daniels", all time travelers were bound by the observance of strict procedures set forth in the Temporal Accords. Daniels stated that the Temporal Accords were enacted after time travel was developed by all time-travel-capable species to prevent catastrophic tampering with the timeline.

In 2153, the Sphere-Builders, a group previously thought to possess the ability only to examine alternate timelines, sent Xindi-Reptilians back to 21st-century Detroit to develop a bio-weapon to destroy the Human race. (ENT: "Carpenter Street")

Because the Sphere-Builders exist in a separate dimension, they may not have had any involvement in the creation of the Temporal Accords.

Ultimately, the war ended when the Na'kuhl returned from an alternate 1944 (created by their very actions) and caused the Cold War to become a war with time travelers changing time as they liked. Daniels brought Enterprise and Archer back to 1944 to stop Vosk, leader of the Na'kuhl, from returning to the future. With the help of Silik, a member of another faction of the Temporal Cold War, Archer shut off Vosk's compound's shields, allowing Enterprise to destroy it and thus destroying the temporal conduit and killing Vosk, just as he was about to travel back to the future. Daniels pulled Archer to a place where they watched the time stream, as all of the events that had occurred while the Temporal War had been ongoing were undone and time reset itself to normal. Archer refused to have anything more to do with Daniels' "damn Temporal Cold War" and Daniels agreed, claiming it was finally coming to an end thanks to Archer's actions. (ENT: "Storm Front", "Storm Front, Part II")

After the temporal wars, time travel was banned, and its technology destroyed. (DIS: "That Hope Is You, Part 1")

In 3189, after Philippa Georgiou started to die from being separated from her own time and the mirror universe for so long, the crew of the temporarly-displaced USS Discovery sought help from a being who turned out to be the embodiment of the Guardian of Forever. After testing Georgiou and Michael Burnham, the Guardian of Forever sent Georgiou back to a time when the two universes were still aligned and thus she could survive. (DIS: "Terra Firma, Part 1", "Terra Firma, Part 2")

Opinions on time travel

Neelix believed that food could be like time travel; in his own words, "You inhale an aroma, take a bite of something and suddenly, bam! You're back at the moment you first tasted it." (VOY: "Workforce")

When Captain Jonathan Archer saw an old clipper ship on an ocean on the Akaali homeworld, he noted that it was almost like "traveling back in time." (ENT: "Civilization")

Methods

• Black hole created by red matter
• Chrono deflector
• Nexus
• Orb of Time
• Q superpowers
• Red Angel suit using a time crystal
• Slingshot effect (Light-speed breakaway factor)
• Temporal causality loop
• Temporal conduit
• Temporal transporter
• Temporal vortex
• Time portal
• Timeships
• Wormholes

Appendices

See also

• Department of Temporal Investigations
• Janeway Factor
• Temporal anomaly
• Temporal Integrity Commission
• Temporal Prime Directive

Background information

A list of episodes that feature time travel.

Episode	Departure	Destination	Time travelers	Method
"The Naked Time"	2266	2266 (three days in the past)	USS Enterprise with crew	cold start
	Alternate 2266	2266 (prime timeline)	USS Enterprise with crew	Unknown (presumably occurred after events of episode)
"Tomorrow is Yesterday"	2267	1969	USS Enterprise with crew	slingshot effect
	Alternate 1969	earlier in 1969 (prime timeline)	USS Enterprise with crew, John Christopher, and an air police staff sergeant	slingshot effect
	Alternate 1969	2267 (prime timeline)	USS Enterprise with crew	slingshot effect
"The City on the Edge of Forever"	2267	1930	Leonard McCoy	Guardian of Forever
	2267	Alternate 2267	James T. Kirk, Spock, Montgomery Scott, Nyota Uhura, Galloway, Guardian of Forever, and a security officer	Guardian of Forever
	Alternate 2267	1930	James T. Kirk and Spock	Guardian of Forever
	Alternate 2267	2267 (prime timeline)	Montgomery Scott, Nyota Uhura, Galloway, Guardian of Forever, and a security officer	Guardian of Forever
	Alternate 1930	2267 (prime timeline)	James T. Kirk, Spock, and Leonard McCoy	Guardian of Forever
"Assignment: Earth"	2268	1968	USS Enterprise with crew	slingshot effect
	Alternate 1968	2268	USS Enterprise with crew	slingshot effect
"All Our Yesterdays"	2269	Unspecified past time period	James T. Kirk	atavachron
	2269	c. 2700 BC	Spock and Leonard McCoy	atavachron
	Unspecified past time period	2269	James T. Kirk	atavachron
	c. Alternate 2700 BC	2269 (prime timeline)	Spock and Leonard McCoy	atavachron
	2269	Unspecified past time period	Atoz	atavachron
	In addition, it is mentioned that the entire populace of Sarpeidon (including the Prosecutor) as well as many others in the centuries beforehand (including Zarabeth and her family) had previously used the atavachron to travel to the past.
"Yesteryear"	2269	Unspecified past time period	James T. Kirk, Spock, and Erickson	Guardian of Forever
	Unspecified past time period	2269	James T. Kirk, Spock, and Erickson	Guardian of Forever
	2269	2237	Spock	Guardian of Forever
	2237	2269	Spock	Guardian of Forever
Star Trek IV: The Voyage Home	2286	1986	HMS Bounty with crew	slingshot effect
	Alternate 1986	2286 (prime timeline)	HMS Bounty with crew, Gillian Taylor, George, and Gracie	slingshot effect
"We'll Always Have Paris"	The USS Enterprise-D (as well as the USS Lalo, the Coltar IV colony, and the Ilecom system) experiences several short time loops (the Manheim Effect) in this episode caused by a "window" into another dimension.
"Time Squared"	2365	6 hours earlier in 2365	Jean-Luc Picard (aboard the shuttlepod El-Baz)	energy vortex
"Yesterday's Enterprise"	2366	2344	Various particles floating through space (presumably)	temporal rift
	Alternate 2344	2366 (prime timeline)	USS Enterprise-C with crew	temporal rift
	2366 (prime timeline, altered through unknown means to appear as an alternate timeline where the USS Enterprise-C disappeared through a vortex)	Alternate 2344	USS Enterprise-C with crew and Alternate/resurrected Natasha Yar	temporal rift
"Captain's Holiday"	27th century	22nd century	Kal Dano	unknown
	27th century	2367	Ajur and Boratus	Vorgon technology
"A Matter Of Time"	26th century	22nd century	Unknown male (aboard a time-pod)	temporal distortion
	22nd century	2368	Berlinghoff Rasmussen (aboard a time-pod)	temporal distortion
	2368	22nd century	A time-pod	temporal distortion
"Cause And Effect"	2278	2368	USS Bozeman with crew	temporal distortion
"Time's Arrow"	2368	1893	Two Unnamed Devidians and Data	temporal vortex
	1893	2368	Two Unnamed Devidians	temporal vortex
	2368	1893	Two Unnamed Devidians, Jean-Luc Picard, William T. Riker, Deanna Troi, Geordi La Forge, and Beverly Crusher	temporal vortex
	The two Devidians apparently made many trips before and perhaps during the episode to 1893 that were not shown, via temporal vortex.
"Time's Arrow, Part II"	1893	2368	male Devidian, William T. Riker, Deanna Troi, Geordi La Forge, Beverly Crusher, Samuel Clemens, and Data's headless body	temporal vortex
	2368	1893	Samuel Clemens	temporal vortex
	1893	2368	Jean-Luc Picard	temporal vortex
"Tapestry"	2369	2327	Jean-Luc Picard's consciousness and Q	Q powers
	2327	2369	Jean-Luc Picard's consciousness and Q	Q powers
	2369	2327	Jean-Luc Picard's consciousness and Q	Q powers
	2327	2369	Jean-Luc Picard's consciousness and Q	Q powers
	Picard thought the time travel may have been an illusion created by Q.
"Timescape"	Time is slowed considerably before being reversed due to being trapped in a temporal fragment. Both the USS Enterprise-D and a Romulan warbird were trapped, and a runabout with Jean-Luc Picard, Deanna Troi, Geordi La Forge, and Data entered the fragment.
"Firstborn"	~2410	2370	Alexander Rozhenko	unknown
	2370	~2410	Alexander Rozhenko	unknown
"All Good Things..."	2370	multiple jumps between to and from an alternate 2364, an alternate 2370 and an alternate future	Jean-Luc Picard's consciousness	Q powers
	alternate 2370	alternate 3.5 billion years ago	Jean-Luc Picard and Q	Q powers
	alternate 3.5 billion years ago	alternate 2364	Jean-Luc Picard's consciousness	Q powers
	It is unknown how many trips Picard made before he became aware of it (his memory was getting better with each trip).
Star Trek Generations	2293	2371	James T. Kirk	Nexus
	2371	earlier in 2371	Jean-Luc Picard	nexus
Star Trek: First Contact	2373	2063	Borg sphere and crew (including the Borg Queen)	temporal vortex
	2373	Alternate 2373	USS Enterprise-E and crew	Side effect of Borg traveling back through temporal vortex
	Alternate 2373	2063	USS Enterprise-E and crew	temporal vortex
	Alternate 2063	2373 (prime timeline)	USS Enterprise-E and crew	temporal vortex
"Past Tense, Part I"	2371	2024	Julian Bashir, Jadzia Dax, and Benjamin Sisko	transporter malfunction
"Past Tense, Part II"	2371	1930	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	1930	2371	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	2371	1967	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	1967	2371	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	2371	2048	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	2048	2371	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	2371	2024	Kira Nerys and Miles O'Brien	simulated transporter malfunction
	2024	2371	Julian Bashir, Jadzia Dax, Kira Nerys, Miles O'Brien, and Benjamin Sisko	simulated transporter malfunction
"Visionary"	2371	2371 (five hours later)	Miles O'Brien	temporal displacement
	2371	2371 (five hours before)	Miles O'Brien	temporal displacement
	2371	2371 (five hours later)	Miles O'Brien	temporal displacement
	2371	2371 (five hours before)	Miles O'Brien	temporal displacement
	2371	2371 (five hours later)	Miles O'Brien	temporal displacement
	2371	2371 (five hours before)	Miles O'Brien	temporal displacement
	2371	2371 (five hours later)	Miles O'Brien	temporal displacement
	2371	2371 (five hours before)	Miles O'Brien	temporal displacement
	2371	2371 (five hours later)	Miles O'Brien	temporal displacement
	2371	2371 (five hours before)	Miles O'Brien	temporal displacement
	2371	2371 (three and a half hours later)	Miles O'Brien	temporal displacement
	2371	2371 (three and a half hours before)	Miles O'Brien (future version)	temporal displacement
"The Visitor"	2372	2372 (few months later)	Benjamin Sisko	temporal displacement
	2372	2373	Benjamin Sisko	temporal displacement
	2373	2389	Benjamin Sisko	temporal displacement
	2389	2408	Benjamin Sisko	temporal displacement
	2408	2422	Benjamin Sisko	temporal displacement
	2422	2450	Benjamin Sisko	temporal displacement
	2450	2372	Benjamin Sisko	temporal displacement
"Little Green Men"	2372	1947	Quark's Treasure with crew (Nog, Odo, Quark, and Rom)	time warp
	1947	2372	Quark's Treasure with crew (Nog, Odo, Quark, and Rom)	time warp
"Accession"	22nd century	2372	Akorem Laan (aboard his lightship)	Prophet ability
	2372	22nd century	Akorem Laan (aboard his lightship)	Prophet ability
"Trials and Tribble-ations"	2373	2268	USS Defiant with crew and Arne Darvin	Orb of Time
	2268	2373	USS Defiant with crew and Arne Darvin	Orb of Time
"Children of Time"	2373	22nd century	(alternate) USS Defiant with crew	energy barrier
"Wrongs Darker Than Death or Night"	2374	2346	Kira Nerys	Orb of Time
	2346	2374	Kira Nerys	Orb of Time
"Time's Orphan"	2374	21st century	Molly O'Brien	time portal
	21st century (ten years later)	2374	Molly O'Brien	time portal
	2374	21st century	Molly O'Brien	time portal
	21st century	2374	Molly O'Brien (young version)	time portal
"The Sound of Her Voice"	2371	2374	Lisa Cusak's distress call and subsequent transmissions	metreon radiation
	2374	2371	USS Defiant response transmissions	metreon radiation
"Parallax"	2371	2371 a short time before	Kathryn Janeway and B'Elanna Torres	event horizon of a quantum singularity
"Time and Again"	2371	2371 (about a day before)	Kathryn Janeway and Tom Paris	subspace fractures
"Eye of the Needle"	2371	2351	test cylinder	Micro-wormhole
	2351	2371	Telek R'Mor	Micro-wormhole
	2371	2351	Telek R'Mor	Micro-wormhole
"Death Wish"	2372	Big Bang	USS Voyager with crew and Quinn	Quinn's power
	2372	Big Bang	Q	Q's power
	Big Bang	2372	USS Voyager with crew, Q, and Quinn	Q's power
"Future's End"	29th century	2373	Timeship Aeon and Captain Braxton	The Aeon's temporal matrix creating a temporal rift
	2373	1996	USS Voyager and crew	destabilized temporal rift
	2373	1967	Timeship Aeon and Captain Braxton	destabilized temporal rift
"Future's End, Part II"	29th century	1996	Timeship Aeon and Captain Braxton	The Aeon's temporal matrix creating a temporal rift
	1996	2373	USS Voyager and crew, Timeship Aeon and Captain Braxton	The Aeon's temporal matrix creating a temporal rift
	2373	29th century	Timeship Aeon and Captain Braxton	The Aeon's temporal matrix creating a temporal rift
"Before and After"	2379	2379 (weeks earlier)	Kes	temporal flux created by a bio-temporal chamber
	2379	2379 (weeks earlier)	Kes	temporal flux created by a bio-temporal chamber
	2379	2379 (months earlier)	Kes	temporal flux created by a bio-temporal chamber
	2379	2378	Kes	temporal flux created by a bio-temporal chamber
	2378	unknown (years earlier)	Kes	temporal flux created by a bio-temporal chamber
	unknown	2374	Kes	temporal flux created by a bio-temporal chamber
	2374	2373	Kes	temporal flux created by a bio-temporal chamber
	2373	2371	Kes	temporal flux created by a bio-temporal chamber
	2371	2369	Kes	temporal flux created by a bio-temporal chamber
	2369	unknown (months earlier)	Kes	temporal flux created by a bio-temporal chamber
	unknown	unknown (months earlier)	Kes	temporal flux created by a bio-temporal chamber
	unknown	2373	Kes	temporal flux created by a bio-temporal chamber
"Timeless"	2390	2375	phase calculations and a letter	temporal transmitter
"Relativity"	2375	29th century	Seven of Nine	temporal transporters
	29th century	2372	Seven of Nine	temporal transporters
	29th century	2372	Captain Braxton	temporal transporters
	2372	2371	Seven of Nine and Captain Braxton	temporal transporters
	2371	2375	Seven of Nine and Captain Braxton	temporal transporters
	2375	29th century	a different Seven of Nine, Captain Braxton and Kathryn Janeway	temporal transporters
	29th century	2372	Kathryn Janeway	temporal transporters
	2372	29th century	Kathryn Janeway and another Captain Braxton	temporal transporters
	29th century	2375	Kathryn Janeway and Seven of Nine	temporal transporters
"Fury"	2376	2371	Kes	energy surge in USS Voyager's warp core, created by Kes
"Shattered"	2377	late 2372	Chakotay	temporal rift
	late 2372	2371	Chakotay	temporal rift
	2371	early 2372	Chakotay	temporal rift
	early 2372	late 2372	Chakotay	temporal rift
	late 2372	2371	Chakotay	temporal rift
	2371	2375	Kathryn Janeway and Chakotay	temporal rift
	2375	2373	Kathryn Janeway and Chakotay	temporal rift
	2373	2394	Kathryn Janeway and Chakotay	temporal rift
	2394	2374	Kathryn Janeway and Chakotay	temporal rift
	2374	late 2372	Kathryn Janeway and Chakotay	temporal rift
	late 2372	2373	Kathryn Janeway and Chakotay	temporal rift
	2373	2375	Kathryn Janeway and Chakotay	temporal rift
	2375	2371	Kathryn Janeway and Chakotay	temporal rift
	2371	2377	Kathryn Janeway and Chakotay	temporal rift
	2377	early 2372	Kathryn Janeway, Chakotay and Tom Paris	temporal rift
	2371	early 2372	Harry Kim, B'Elanna Torres and Ayala	temporal rift
	2374	early 2372	Seven of Nine	temporal rift
	2394	early 2372	Adult Icheb and Adult Naomi Wildman	temporal rift
	early 2372	2377	Chakotay	temporal rift
"Endgame"	2404	2378	The SC-4 and Admiral Kathryn Janeway	chrono deflector
"Cold Front"	31st century	2151	Daniels	time portal
"Shockwave"	2152	2152 (ten months in the past)	Jonathan Archer	time portal
	2152	31st century	Jonathan Archer and Daniels	time portal
"Shockwave, Part II"	31st century	2152	Jonathan Archer	temporal chamber
"Future Tense"	2152	2152 (few minutes in the past)	Charles Tucker III and Malcolm Reed	temporal radiation
	2152	2152 (few minutes in the past)	Charles Tucker III and Malcolm Reed	temporal radiation
	2152	2152 (few minutes in the past)	Jonathan Archer and Malcolm Reed	temporal radiation
	2152	2152 (few minutes in the past)	Jonathan Archer and Malcolm Reed	temporal radiation
"Carpenter Street"	2153	2004	Jonathan Archer and T'Pol	time portal
	2004	2153	Jonathan Archer, T'Pol, Damron, and a Xindi-Reptilian guard	time portal
"Azati Prime"	2153	26th century (possible timeline)	Jonathan Archer and Daniels	time portal
	26th century (possible timeline)	2153	Jonathan Archer	time portal
"E²"	2154	2037	Enterprise and crew	subspace corridor
"Zero Hour"	2154	2161	Jonathan Archer and Daniels	time portal
	2161	2154	Jonathan Archer	time portal
	2154	1944	Enterprise, her crew, and Daniels	time portal
"Storm Front" and "Storm Front, Part II"	1944	2154	Enterprise and crew	time portal
Star Trek	2387	2233	Narada and crew	black hole
	2387	2258	Jellyfish and Spock	black hole
"Magic to Make the Sanest Man Go Mad"	2256	2256 (30 minutes earlier; unspecified number of occasions)	Harry Mudd	time crystal
"What's Past Is Prologue"	2257	Nine months later in 2257	USS Discovery and crew	mycelial network
"The Red Angel"	32nd century	2257	Gabrielle Burnham	Red Angel
"Perpetual Infinity"	2236	32nd century	Gabrielle Burnham	Red Angel
	2257	32nd century	Gabrielle Burnham	Red Angel
"Such Sweet Sorrow, Part 2"	2257	Various points throughout 2257	Michael Burnham	Red Angel
	2258	32nd century	Michael Burnham, USS Discovery, and crew	Red Angel
"That Hope Is You, Part 1"	3188	2258	Red angel suit	Red Angel
"Terra Firma, Part 1"	3189	2255 (mirror universe)	Philippa Georgiou (mirror)	Guardian of Forever
"Terra Firma, Part 2"	2255 (mirror universe)	3189	Philippa Georgiou (mirror)	Guardian of Forever
"Terra Firma, Part 2"	3189	A time when the prime and mirror universes were still aligned	Philippa Georgiou (mirror)	Guardian of Forever
"Assimilation"	Alternate 2401	2024	Crew of the CSS La Sirena	slingshot effect
"Farewell"	2024	2401	Jean-Luc Picard, Raffaela Musiker, Seven of Nine and Elnor	Q's powers
"A Quality of Mercy"	Unknown time after alternate 2266	2259	Alternate Christopher Pike	time crystal
"A Quality of Mercy"	2259	Alternate 2266	Christopher Pike	time crystal
"A Quality of Mercy"	Alternate 2266	2259	Christopher Pike	time crystal
"Those Old Scientists"	2381	2259	Bradward Boimler and Beckett Mariner	Krulmuth-B portal
"Face the Strange"	3191	2258	Michael Burnham, Rayner and Paul Stamets	time cycling of the USS Discovery due to a time bug
	2258	2256	Michael Burnham, Rayner and Paul Stamets	time cycling of the USS Discovery due to a time bug
	2256	2258	Michael Burnham, Rayner and Paul Stamets	time cycling of the USS Discovery due to a time bug
	2258	3189	Michael Burnham, Rayner and Paul Stamets	time cycling of the USS Discovery due to a time bug
	3189	3218	Michael Burnham, and Rayner	time cycling of the USS Discovery due to a time bug
	3218	3189	Michael Burnham, Rayner, and Paul Stamets	time cycling of the USS Discovery due to a time bug
	3189	3189 (a different date)	Michael Burnham, Rayner, and Paul Stamets	time cycling of the USS Discovery due to a time bug
	3189	2256	Michael Burnham, Rayner, and Paul Stamets	time cycling of the USS Discovery due to a time bug
	2256	3191	Michael Burnham, Rayner, and Paul Stamets	end of time cycling of the USS Discovery following the removal of a time bug

Apocrypha

In the novel Ishmael, Captain Spock embarked incognito aboard a Klingon ore transport, refitted with time travel capacity. The ore transport managed to go back to 1867 Earth after an acceleration close to a white dwarf near Starbase 12. The USS Enterprise was modified to follow the ship to 1867, becoming the first instance that a Federation ship utilized intentional and controlled time travel.

In the video game Star Trek: The Next Generation - Future's Past for the Super Nintendo, the computer mentions several temporal near-catastrophes in the 23rd century: the New York incident, the above-mentioned "Ishmael incident", and the "Eyeglass Loop Paradox" referring to what Kirk does in Star Trek IV: The Voyage Home with his glasses.

The novel trilogy Star Trek: Deep Space Nine - Millennium features the Defiant inadvertently travelling twenty-five years into the future when they slingshot around a newly-formed red wormhole. Upon arriving in the future, Dax explains that time-travel leavers the travellers molecularly out of sync with the local time period in a manner that can only be averted if they either exactly repeat and reverse the process that sent them through time in the first place or if they travel in the opposite direction of their original trip by a considerably greater distance (in this case, it was suggested that the Defiant crew could travel back in time 25 000 years). It is left unclear what would happen if someone tried to go back in time via a different method- the use of the Orb of Time is suggested as one such method that could be used- but it is generally agreed that such an attempt either wouldn't work or prove unpleasantly fatal to the time traveller.

The Department of Temporal Investigations novels Watching the Clock and Forgotten History go into detail about the principles of time travel, as well as the hows and whys of the various time travel incidents in Star Trek's history. The most significant of these demonstrates how Starfleet became aware that history could change – previously, the organization had assumed that changing history just created an alternate timeline that those who changed history happened to get 'stuck' in-; when the DTI created Timeship One with the intention of deliberately traveling three days into the future, a future version of the ship appeared in their time thirty-two hours before it was due to launch, the crew all dead or dying from an accident that had occurred when they overshot. With this discovery postponing the planned launch, the future Timeship One and its crew disappeared once the time of the original launch had passed, confirming that history could be changed.

External links

• Time travel at Memory Beta, the wiki for licensed Star Trek works
• Time travel at Wikipedia