Timeline

A timeline was a method of ordering chronology, creating a history for an individual, place, event, etc. The term was sometimes used to mean the whole of a version of history, such that a divergent version of the universe could be termed an alternate timeline. However, in other contexts, the Web of Time was said to be made of a number of interweaving timelines or "threads", with individual planets or even people having their own "timelines" which could theoretically be altered independent of the rest of history.
== Uses of the term ==
=== Universe-wide timeline ===
Centring on what the Time Lords called the "primary timeline" (AUDIO: Reborn) alternate timelines could diverge, which if left unchecked, would end the real universe millions of years before it was meant to due to there being only a finite amount of matter and energy in the uni-verse. Such a "sub-universe", the Silurian Earth, was destroyed by the Seventh Doctor. (PROSE: Blood Heat) Owen Harper told Rhys Williams that the Cardiff Space-Time Rift connected to not only other planets, but "other timelines". (TV: Meat)
The Eleventh Doctor referred to the "natural timeline", which he restored when he prevented the New Dalek Paradigm from seizing the Eye of Time, thus averting the alternate timeline they would have established. (GAME: City of the Daleks)
The Eleventh Doctor identified the 2020 Cwmtaff incident as a "temporal tipping point", explaining that it was not a fixed point in time. He claimed that such a tipping point would "change future events, create its own timeline, its own reality." (TV: Cold Blood)
The Eighth Doctor later stated that Time Roaches couldn't be let out of the Time vortex into "the timeline". (AUDIO: Foreshadowing)
On two occasions, the Seventh Doctor pondered that Daleks would think twice before doing something to alter "the timeline". (TV: Remembrance of the Daleks) He made a similar statement abotu "the timestream", suggesting the terms could be used interchangeably. (PROSE: Transit)
Sarah Jane Smith corrected Maria Jackson when she referred to Andrea Yates's world as a parallel world, clarifying that it was their timeline, having been changed. Later, whilst speaking with Sarah Jane, the Trickster identified the world of Andrea Yates as a timeline that he had created. (TV: Whatever Happened to Sarah Jane?) As a result of a later attempt by the Trickster to change history, Clyde Langer found himself in what he repeatedly referred to as an alternative timeline. (TV: The Temptation of Sarah Jane Smith)
When Rhys Williams expressed shock at the sight of a pterodactyl, which he knew to be extinct, Captain Jack Harkness clarified that pterodactyls were extinct in "[his] timeline". (TV: Meat)
Stressing the danger of using the null field generator on Earth in 2011, Captain Jack told Esther Drummond and Rex Matheson that he had seen the future, that he had "walked the future world". He warned that, with the generator, the timeline would become "terminal". (TV: End of the Road)
When dealing with the interference of the Star Men, the Fifth Doctor mentioned that they were damaging the "timeline," the "timelines," and that they had inserted themselves into "this reality's timestream." (AUDIO: The Star Men
=== Plural timelines ===
The meta-structure of history, (PROSE: The Book of the War) often "the Web of Time", (TV: Attack of the Cybermen, etc.) was made up of interweaving "threads" or "lines" of causality, which converged at the caldera on the Homeworld. (PROSE: The Book of the War)
As such, the whole of history could be referred to as "the timelines", multiple rather than singular. and the Daleks manipulated and shifted "the timelines" to conquer Earth in 1921 (AUDIO: Master of the Daleks) and the Sanukuma described the Last Great Time War as being raged across "the timelines," (AUDIO: The Rulers of the Universe) the effects of the war affecting "the timelines". (AUDIO: The Starship of Theseus, One Life) During the war, the Daleks developed the annihilator weapon which could erase a whole species without "affecting the timelines", meaning they would still be remembered even though they'd never existed. (AUDIO: Legion of the Lost)
Following his first regeneration during the Last Great Time War, dismissed the Daleks as "microbes" who were "tied to one timeline". (AUDIO: Homecoming)
The dimension cannon was capable of "measuring" timelines, and Rose saw that they all converged on Donna Noble. (TV: Journey's End)
The Eleventh Doctor found that "the timelines [were] too scrambled" for him to return to New York, preventing him from recovering Amy Pond and Rory Williams after they were displaced in time by a Weeping Angel. (TV: The Angels Take Manhattan)
The Thirteenth Doctor told her companions that Orphan 55 was but "one possible future" and "one timeline" which was not fixed. (TV: Orphan 55)
The Thirteenth Doctor sent a message from the TARDIS "through the timelines" into the Time Vortex, purposefully drawing the attention of a Dalek ship which lay in wait there. (TV: Revolution of the Daleks)
==== Personal timelines ====
In this understanding of the word "timeline", individuals could be said to have personal timelines.
The Tenth Doctor explained to Donna Noble that he could not use a time machine prevent her from missing her wedding as he "apparently" could not go back on someone's personal timeline. (TV: The Runaway Bride)
Captain Carter explained to the Eleventh Doctor that the Justice Department's Teselecta extracted criminals near the end of their established timelines before they punished them. (TV: Let's Kill Hitler)
As Tasha Lem explained to the Eleventh Doctor, the Kovarian Chapter travelled back along his timeline in an ultimately vain attempt to prevent him from reaching Trenzalore. (TV: The Time of the Doctor) Missy told the Twelfth Doctor that she had been "up and down his timeline", meeting people who had died for him. (TV: Death in Heaven) The whole of the Doctor's time stream could be accessed from his tomb on Trenzalore. (TV: The Name of the Doctor)
Altering one's personal timeline was dangerous and unpredictable, and one of the limits on when time travellers could or could not change the past. The Ninth Doctor explained to Rose Tyler that he could not go back and warn humanity of a Dalek invasion because once the TARDIS landed he became part of events, "stuck in the timeline". Soon after, he apparently realised that he could indeed "cross [his] own timeline", however, this was but a ruse to get Rose into the TARDIS to safety. (TV: The Parting of the Ways) Similarly, the Tenth Doctor told Wilfred Mott that he could not go back in time and catch yesterday as he could not go back within "[his] own timeline", that he had to stay relative to the Master within the causal nexus. (TV: The End of Time)
Revealing to the Tenth Doctor that he had went to see Rose at the Powell Estate before she had met him, Jack Harkness cited "timelines and all that" as he clarified that he did not approach her. (TV: Utopia)
Having been sent back in time and buried alive in the year 27, Jack Harkness observed that he had crossed his own timeline when he was eventually uncovered by agents of Torchwood Cardiff in 1901 whilst his past self was working for them. As such, Jack instructed them to cyrofreeze him until just after he had been sent back in time so that he would not come into contact with himself. (TV: Exit Wounds)
 explained to that the two of them coming into contact "put the timelines out of sync". As a result, the Master would not retain his memory of the event and so Missy would not remember having met herself. However, Missy did evidently remember enough to keep a spare dematerialisation circuit, (TV: The Doctor Falls) and her theory was disputed by yet other accounts. (PROSE: The Eight Doctors, TV: Time Crash)
The Twelfth Doctor told Clara Oswald that he could not prevent the death of Danny Pink as to do so would create a paradox loop by changing the events, meaning that Clara would have had no cause to ask the Doctor, risking the disintegration of the timeline, her timeline. By linking Clara to the telepathic interface, the TARDIS led her and the Doctor to the 3W Institute, which was deemed to be the most likely point that Clara's timeline would re-intersect with that of Danny. (TV: Dark Water)
Yasmin Khan was warned by the Thirteenth Doctor that her "whole timeline" could be erased if something happened to her grandmother in 1947. (TV: Demons of the Punjab)
== Universal history ==
The timeline of the universe spanned billions of years. However, most of the Doctor's involvement seemed to be in what was sometimes called the Humanian Era, that part of history which encompassed human existence. As a result, the Doctor's TARDIS was most often seen between the time humans first evolved through to about the 82nd century. Occasionally, the Doctor went further than the 100th century, into what might be called the "far future".
The Doctor was known to have visited, or at least been affected by, people and places in the following broad divisions of time as measured by at least one human dating system:
* Pre-universe
* Dark Times
* Distant past
* BC years
* Far future
* After-universe
However, their travels were usually known to have occurred at much more specific times. The Doctor and their companions were active in the following Earth centuries:
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