I haven't done much research into it (jus a little bit of looking glass stuff) and would be very interested to hear more informed takes on the matter but I will say this; I think the idea of "time travel" has been sullied by tv/movies purposely...the idea of moving people or things backwards or forwards is kind of stupid while the idea of communication between different planes/times/universes is an old one shared by many cultures, using many different methods.