In James Blish's The Quincunx Of Time, Service agents know of the future because they receive messages from future periods, then ensure that the events described in those messages occur.
Poul Anderson's Time Patrol agents observe unrecorded past events in order to know the course of the history that they must protect from extratemporal interference.
Anderson's contending Wardens and Rangers, living in our future, try to influence their future by controlling unrecorded details of past history.
In Anderson's There Will Be Time, two groups of mutant time travelers contend. One group changes the significance of known events.
The temporal agents in Robert Heinlein's "'- All You Zombies -'" cannot prevent events but sometimes cause them.
Heinlein's Lazarus Long visits the period of his childhood but to no good purpose.
Isaac Asimov's time traveling "Eternals" change events to maximize human happiness until they themselves are prevented from existing but I argue that Asimov's narrative is incoherent. See The Logic of Time Travel: Part II, here.
There is time travel between two periods of Brian Aldiss' future history, Galaxies Like Grains Of Sand.
Kaor, Paul!
ReplyDeleteAnd it was the preference of the Time Patrol to interfere as little as possible with the unrecorded history studied by its specialists. And, of course, guard against interference with that history by time criminals.
There were some unusual exceptions, such as the events recorded in "The Only Game In Town."
Ad astra! Sean
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