Hints

Members of a time travelling organization will be familiar with periods that are both past and future to us as Poul Anderson brings out in his first Time Patrol story, "Time Patrol," collected in Time Patrol. In addition to the "present," 1954, there are several past years of action and even a past geological period, the Oligocene. The series will focus mainly on our historical past. However, the time criminal, Rozher Schtein, from 2987, has stolen a time shuttle from the still later Ing Empire. These periods are casually mentioned as if the characters are just as familiar with them as they are with 1894, 464 and 1944. And, of course, time machines are invented in 19352 AD, a date that is never again mentioned in the series. Anderson is good at McGuffins, e.g., an Ing merchant travelled to 2987 to barter for synthrope because the secret of its production had been lost in the Interregnum. We learn nothing more about the Ing Empire, synthrope or the Interregnum. They serve only to enable Schtein to steal a time machine. We learn just enough about conditions in 2987 to understand Schtein's motivation to change history. His family was killed in an interplanetary raid.

Another time travel narrative that presents incomplete hints about the future is HG Wells' "The Chronic Argonauts":

a ward will be abducted in 4003;

public officials will be assaulted in 17,901 and 17,902.

If Wells had completed this earlier and very different version of The Time Machine, then we might have learned more. But, however much an author writes, he can always leave hints of more.