Time Time was a fundamental physical quality , measuring the duration of events and the intervals between them . It could be seen as part of the fundamental structure of the universe , a dimension in which events happened in sequence . Space - time vessel s , such as TARDIS es , could travel along this dimension in the same way that ordinary space vessels could travel along the other dimensions . Having passed through the Time Vortex so often , the Doctor , and those who travelled with him , developed a " special relationship " with time , making them more sensitive to its nuances . ( TV : " City of Death " ) Structure of time . When Clara Oswald asked what time was made of , the Eleventh Doctor assured her that it wasn ' t of strawberries . ( TV : " The Rings of Akhaten " ) Instead , at a lower level , time was quantized , like a force , which ( in the guise of " Professor Thascalos " ) described as made up of particles known as chronon s . ( TV : " The Time Monster " ) Chronons , like other particles , could be detected and interacted with . ( GAME : " City of the Daleks " ) While the Weeping Angel s were able to feed on the potential energy gained by displacing people into the past ( TV : " Blink " ) , even they could not feed on raw time energy . Such energy , leaking out of cracks in the structure of the universe , absorbed an army of Angels at the crash of the " Byzantium " , completely removing them from history . ( TV : " Flesh and Stone " ) The Doctor suspected that the CyberKing walking over Victorian London and the Dalek s invading Earth in Amy Pond ' s era had been similarly erased , ( TV : " Flesh and Stone " ) and later saw Rory Williams absorbed by time energy . ( TV : " Cold Blood " ) Artron energy was also in some way connected with time , in a manner that was possibly too complicated for Time Lords to fully explain to humans . ( TV : " Four to Doomsday " , " The Deadly Assassin " , " Dalek " , etc . ) The structure of time had to be balanced or ordered in some way , a purpose of the Web of Time . ( TV : " Attack of the Cybermen " ) Additionally , time had a holistic structure like a balloon . If a mishap in time travel punched a hole in that structure , the universe could die in a matter of centuries . ( TV : " The Two Doctors " ) Time travel . New connections between different points in space - time could be created : for instance by time window s created by warp drive s ( TV : " The Girl in the Fireplace " ) ; time storm s created by Fenric ( TV : " Dragonfire " , " Silver Nemesis " , " The Curse of Fenric " ) ; or the crack s in the skin of the universe , which suddenly appeared at various times and places in the universe after a temporal explosion . ( TV : " Flesh and Stone " , " The Vampires of Venice " ) Furthermore , travel from any point to another was possible by passing through the Time Vortex , by using a vehicle such as a TARDIS or Dalek time machine ( TV : " The Chase " , etc . ) or a device such as a vortex manipulator ( TV : " Utopia " , " The Sound of Drums " , TV : " Everything Changes " , etc . ) , by creating a wormhole such as a time corridor ( TV : " The Evil of the Daleks " , etc . ) , or even through direct psychic teleportation . ( TV : " Planet of the Spiders " ) Other races eventually learned to travel through time . These included the Dalek s ( TV : " The Chase " ) and human s . ( TV : " Invasion of the Dinosaurs " ) In the 51st century , humans established the Time Agency . ( TV : " The Talons of Weng - Chiang " , " The Empty Child " ) The Time Lord s , however , tried to keep strict controls on " unauthorised " use of time travel by other species . ( TV : " The Time Warrior " , " The Two Doctors " ) Changing history . The Tenth Doctor laboured in an effort to explain to humans how time was misunderstood and never strictly linear , that it was made up of " wibbly - wobbly , timey - wimey . . . stuff . " ( TV : " Blink " ) Another time , he tried making it easier for his companion , Martha Jones , to understand by referencing " Back to the Future " to explain the mechanics of the " infinite temporal flux " ; if the Carrionite s succeeded in freeing the rest of their kind and taking over Earth , Martha would vanish as the future she came from would no longer exist . ( TV : " The Shakespeare Code " ) Travelling into the past allowed changing the future . As the Eleventh Doctor put it , " Time can shift . Time can change . Time can be rewritten . " ( TV : " Flesh and Stone " ) However , erasing events from history did not always automatically change the future . Time travellers were able to remember the " original " timeline ( TV : " Flesh and Stone " ) , unless the erasure directly affected their life ( TV : " Cold Blood " ) , in which case they had to make an extraordinary effort to do so . Blocking chronons ( e . g . , with a TARDIS or a special - built device ) could prevent objects from vanishing even though they no longer had a past . ( GAME : " City of the Daleks " ) In a similar way , a paradox machine could be built ( e . g . , from a cannibalised TARDIS ) to allow time paradox es to persist without effect . ( TV : " The Sound of Drums " , " Last of the Time Lords " ) In a universe with time travel and a malleable space - time , there would be no fundamental stable meta - structure to history . However , the Time Lords imposed one , which they called the Web of Time , which connected the fragmentary nodes of history into a single whole . ( AUDIO : " Neverland " ) This Web required maintenance , as when the Sixth Doctor explained that the destruction of Earth in 1985 would disrupt the Web . ( TV : " Attack of the Cybermen " ) Even in the post - Gallifrey universe , some events were fixed points which " must " happen . One example was the volcanic eruption of Mount Vesuvius at Pompeii . ( AUDIO : " The Fires of Vulcan " , TV : " The Fires of Pompeii " ) Changing fixed point events required highly advanced technology , and doing so could cause major damage to the continuum . ( GAME : " City of the Daleks " ) Other moments were in flux , allowing minor changes to history . Some events even allowed dramatic changes in history , especially after the demise of the Time Lords in the Last Great Time War . ( TV : " The Unquiet Dead " ) An example of this occurred in 2020 , when a drilling operation in Cwmtaff altered the future of the Earth by bringing humanity into contact with the Silurian s , which could have led to either a peaceful relationship or a devastating war . The Eleventh Doctor described these events as opportunities . ( TV : " Cold Blood " ) Parallel universes and alternate timelines . At historical choice points , the timeline naturally diverged , creating two parallel universe s . ( TV : " Inferno " , etc . ) These parallel universes could be reached through the Time Vortex before the Last Great Time War , but in the post - Gallifrey universe this became much more difficult , and dangerous to the structure of space - time . ( TV : " Rise of the Cybermen " , " Doomsday " ) Changing history by time travel , in a way inconsistent with the meta - structure of space - time , would create an alternate timeline , which had a similar effect . Historically , the Time Lords would alter history to prevent these alterations from having ever happened , negating the alternate timeline in all but the memories of time travellers who participated in them . ( TV : " Day of the Daleks " , PROSE : " " , TV : " The Big Bang , HOMEVID : Good Night " ) However , some time travellers were left confused as to how they could accept multiple different realities in their heads . Even Time Lord s such as the Doctor didn ' t know how to explain this properly . ( TV : " Space " , HOMEVID : " Bad Night / Good Night " ) In the post - Gallifrey universe , the Doctor and others often acted on their own to do the same . ( TV : " Turn Left " , " Last of the Time Lords " , " The Mad Woman in the Attic " , etc . ) Personification . Like other cosmic principles , time was embodied by an Eternal , named Time , who chose the Seventh Doctor as her champion . ( PROSE : " Happy Endings " )