ntt@dciem.UUCP (Mark Brader) (05/24/84)
You can create paradoxical situations, that's what. (Even if the "going backwards" is only FTL travel, you can still do it, by radio control.) Powerful evidence against the possibility of this kind of thing in real life is the rarity of people who never had parents, and that sort of thing. On the other hand, this can also be explained by Niven's Law: "If the universe permits time travel and changing the past, then time travel will never be invented in that universe." (Because sooner or later, someone will travel back and kill the inventor or something because they don't care for time travel.) Mark Brader
kcarroll@utzoo.UUCP (Kieran A. Carroll) (05/24/84)
* True, the ability to go backwards in time seems to create the possibility for paradoxical situations being generated. However, this doesn't give the death-blow to time-travel. I mean, science-fiction writers have been coming up with dodges around that problem for the last 40 or 50 years! One possibility: the "structure" of all events in space-time cannot be changed, and that includes all actions taken by time travellers. ie. if you go back in time to kill your grandfather, either your gun wil jam, you'll end up deciding not to, etc., or you'll succeed, only to find out that your father was a bastard (you killed the wrong guy!) Or, maybe the Time Patrol will come and stop you... 2) Alternate realities split off whenever the universe reaches a decision nexus; if you kil your grandfather, then when you return to the future, it'll indeed be one in which you weren't born. However, the other time track still exists, in some suitably metaphysical sense. etc. -Kieran A. Carroll ...decvax!utzoo!kcarroll