After the time of the first books, Pern undergoes a technological revival engendered by the
rediscovery of the Admin AI built by the original colonists. An ambitious plan to eliminate
Thread forever (yeah, like that’s gonna happen) hinges on time travel and blowing up
engines on the Red Star.
Jaxom shrugged as he changed pages. “A dragon has to know exactly the time
when he is going to, or he can come out of
between at the same spot he’s inhabiting at that earlier time. Too
close, and it is thought that both dragon and rider will die. Equally, it’s unwise to
go any place you haven’t already been, so you shouldn’t go forward, because you
wouldn’t know if you were there or not.”