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. (DW: Colony in Space) Most Earth colonies during this time were "terrible places." (NA: Christmas on a Rational Planet)

Schooling 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. (DW: The Web Planet)

Both Nikki Jupiter, a Tenth Doctor companion, and Vicki, a First Doctor assistant, were natives of this century.

Some other cultural tidbits of the 25th century included:
 * The Beatles were considered "classical music", and a theatre dedicated to them existed in Liverpool. (DW: The Chase)
 * Aspirin tablets were no longer in common use. (DW: The Web Planet)
 * Humanity travelled in hyperspace. Such journeys were common and commercial. (NSA: Judgement of the Judoon)