From: James Richmond (Avatar) 28/06/00 14:22:53 Subject: re: time travel post id: 91268 There are a number of possible scenarios which could occur in the "grandfather paradox" situation. Science fiction has dealt very well with all the variations. Here are a few which spring to mind: Backwards time travel (BTT) turns out to be impossible. BTT is possible, but only to observe past events. It is impossible to change the past in any way. BTT is possible and limited changes can be made, but only to times and places which cannot affect one's own future. BTT is possible, and massive changes can be made, but there is some type of physical "temporal censorship" law which prevents actions being carried out which would lead to paradoxes. BTT is possible, but whenever a change is made in the past a new "parallel timeline" is created. The time traveller would then have to choose (or be forced into choosing) whether to return to the "old" future or the "new" future. As above, but parallel timelines are only created when a temporal paradox would otherwise result. BTT is possible, but if a "grandfather"-type paradox occurs this ruptures the spacetime continuum, potentially ending the universe as we know it. BTT is possible, but where a paradox occurs all relevant objects and events caught in the paradoxical loop spontaneously cease to exist. No doubt there are many other possibilities which I haven't covered here. JR This forum is un-moderated. The views and opinions expressed are those of the individual poster and not the ABC. The ABC reserves the right to remove offensive or inappropriate messages.