25th century In the 25th century , the planet Earth , under a repressive government , had a population of a hundred billion people , most of them living on floating islands . It was a highly polluted planet . ( TV : " Colony in Space " ) Most Earth colonies during this time were " terrible places . " ( PROSE : " Christmas on a Rational Planet " ) School ing was quick . Students obtained certificates in a vast range of disciplines by the age of ten . They were taught by machines for one hour a week . In comparison , a 20th century high school was like a nursery . ( TV : " The Web Planet " ) Both Vicki Pallister and Nikki Jupiter , companions of the First and Tenth Doctor s respectively , were natives of this century . Prior to this century , World War IV was fought on Earth . On a visit to London in February 1814 , Vicki noted that St Paul ' s Cathedral survived not only the four World Wars but the 22nd century Dalek invasion . ( AUDIO : " Frostfire " ) Around this time , an Earth expedition led by Professor Parry was trying to uncover the lost tombs of the Cybermen on Telos . There they discovered that the Cybermen , contrary to popular belief , had not gone extinct , but instead gone into frozen hibernation in their huge underground tombs . One of the members of that expedition , Eric Klieg along with his accomplice Kaftan , aimed to use the Cybermen ' s strength , coupled with their intelligence from the Brotherhood of Logicians to transform the Earth Empire into a new power . His plan fell apart and eventually the tombs were sealed shut , supposedly forever . ( TV : " The Tomb of the Cybermen " ) Some other cultural tidbits of the 25th century included : The Doctor once encountered a Stigorax in Birmingham in the 25th century . ( TV : " The Happiness Patrol " ) After arriving in London in 2167 , the First Doctor , yet to determine at which point in time they were , told Ian Chesterson and Barbara Wright to bear in mind that they might have landed in the early 1900s or the 25th century . ( TV : " The Dalek Invasion of Earth " ) By this time , pandas were extinct . ( PROSE : " The Eleventh Tiger " ) The snowy planet of Isen VI was terraform ed into a tropical paradise by Kano Dollar for the warrior princess Thanna . Within three years , the terraforming had inadvertently caused global disaster caused by the long - lost Hyperion Rann - Korr . With the help of the Twelfth Doctor and Clara Oswald , Rann - Korr was frozen within the planet ' s Aurora ocean . ( COMIC : " Terrorformer " ) The 25th century was notable for hosting the life of Darzil Carlisle , initially described by the Fifth Doctor as one of the most eminent advocates for peace in human history . Born outside Olympus Mons on Mars in 2414 , Darzil Carlisle was later relocated to an orphanage in Finchley , north London , at the age of three following a freak airlock accident which killed his parents . In the 2430s , the 17 year old Darzil Carlisle earned a scholarship to the Phobos Academy of Music , proceeding to study for three years before , as quoted by the Doctor , " stumbling into a glorious career as a peace negociator " , in which he was apparently responsible for ending 36 wars . However , the Doctor , following an encounter with an older Darzil Carlisle in the later period of the century , would realise that Darzil ' s career was actually the result of him having taken the credit for actions that he would perform in his personal future . ( AUDIO : " The Game " ) In the mid - 25th century , it was illegal for a human to sleep with a non - human . ( PROSE : " Dead Romance " ) Alternate timeline . Originally , the Ides Scientific Institute faded away as a " footnote " in the 25th century . However , would manipulate history to make the Ides Scientific Institute a major player in human history , ( AUDIO : " Masterplan " ) being at the forefront of space exploration and colonisation technology . ( AUDIO : " The Death of Hope " ) Through the machinations of the Doom Coalition , the end of the universe prematurely came about some time in the 25th century , with the Time Lord s being preserved at the cost of all other life . This outcome , however , was averted when the Doom Coalition was defeated by the Eighth Doctor . ( AUDIO : " The Side of the Angels " , " Stop the Clock " ) In a potential history shown by the Eleventh Doctor to Jean - Luc Picard , the Cybermen , having integrated both the Doctor ' s N - Space and Picard ' s parallel universe before conquering the Borg Collective , continued the campaign to convert the galaxy . Among the races converted en masse during this century were the Klingon s by 2418 , the Raxacoricofallapatorian s by 2448 , the Vulcan s by 2468 , and the Judoon by 2493 . ( COMIC : " Assimilation² " )