Hello everyone I'm new here. I recently watched into darkness, so so movie. It got me thinking about how time travel and the alternate universe work. So here's a thought experiment suppose nuEnterprise decided to sling shot around the sun back to one these dates: 1947, 1968, 1969, 1986, 1996 or 2063. Would they encounter the ships and characters from the original time? If yes where did these ships & people comes from and go back to? Are they just remnants of old timeline like Marty in bbf2? What happens if one of the people from nuEnterprise are on board oldEnterprise, Voyager or Enterprise E when it returns to it's origin? Finally what controls what time line each ship go to when it times travels back "home" the quantum difference mentioned in parallels? The closest sci fi that deals with this kind of thing I've read is Timeline by Michael Crichton, in that book time travel was really just travel between parallel universes. Some of those universes existed in past of the starting universes and changes made in these alternate universes either changed the origin universe or caused the characters to return to a similar universe but with the changes they made represented.