Due to the show's use of time travel as a major plot element, Doctor Who has on many occasions visited a past year which was still the future at the time of the story's writing. For example, various contemporary stories from the original series which were set in their respective decades feature Earth actively involved in interplanetary travel. Later episodes, the new series, and the series Torchwood are written assuming real-life progress in space travel. The UNIT Dating Controversy is an attempt to explain the confused timeline and the technology seen during those episodes.
In the series' revived era, an extra year was created when the program jumped ahead by a year in 2005. By 2007, both Doctor Who and its then-new spin-offs Torchwood and The Sarah Jane Adventures had reestablished present-day in 2007 despite Doctor Who having depicted two successive Christmasses and myriad months of events that remained in-sequence.
Read more about this topic: Floating Timeline, Television, Live Action
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“The conscience of the world is so guilty that it always assumes that people who investigate heresies must be heretics; just as if a doctor who studies leprosy must be a leper. Indeed, it is only recently that science has been allowed to study anything without reproach.”
—Aleister Crowley (1875–1947)