i have proof that backwards time travel is impossible

[DeviousJ]

Originally posted by THRILLHO
i just thought of something right now:

if the universe will continue to expand forever, the future is infinite, regardless of the future of the human race.
which means absolutley everything will happen at one point or not in the future.
now, if backwards time travel is possible, that would mean that the past and present would be infinitley flooded by time travellers from the infinitely long future (the future would be flooded too).

clearly, it is not. our reality is not flooded with an infinite representation of time-travelling life forms or matter from gazillions of years from now. that at least proves the single-universe theory OR backwards time travelling wrong, doesn't it?

Eh, I'm not sure that everything will happen at one point in the future (assuming you're going for a single universe here). The potential is there, but... either something will happen at a particular moment or it won't. Not both. Unless you mean milestones and discoveries... that's still a gray area though. Besides, even if the universe does expand forever, it's going to die eventually. As systems move apart, there'll be less gravity forcing elements together to create new sources of energy. So life will probably die out, unless a race could survive on raw materials. That's possible I guess. It would be pretty dark though. Hasn't the continually expanding universe idea been basically disproven though? I think it has... I'm losing my ability to retain information =/

Here's where the multiple universes come in again. Assuming that an infinite number of lifeforms will be travelling back from an infinite number of futures, there will be an infinite number of universes saturated with them soujourning everywhere. However, there will also be an infinite number of universes where they *don't*. That's the beauty of it - infinity doesn't have to mean 'everything'. Infinity+infinity=infinity. So we could just be in one of the dimensions where no timetravellers ever appear. In this dimension, for people to have already visited, they'd have to have been very discreet (because we have no record of it happening) or they just haven't travelled here. That doesn't mean there aren't alternatives though. We could build a time machine tomorrow, which creates a mile-wide fireball at the destination before you arrive, and travel back to the last Superbowl. Now that wouldn't be very discreet, but nobody remembers it happening right? That's because it didn't happen - in this dimension. However, there is an alternate dimension (or there could be - would they exist before someone was there to experience them?) where that happened, and that's where we'd end up travelling to. So the lack of any evidence doesn't prove people won't end up travelling back in time. Just not to OUR dimension, dammit.

[Mathboy]

Hmmm. The really interesting thing is that if we're talking about multiple branching universes, we're not talking about moving in four dimensions, we're talking about 5, the fifth one being some sort of positional representation of the specific timepoint out of all possible versions of that timepoint.

Amusingly, if we wanted to, we could theoretically call that fifth dimension "probability," but that would have all of us beating our heads with cricket bats because the late, great Douglas Adams already thought of that. Forty Two.

[scouse_dave]

Originally posted by THRILLHO
if the universe will continue to expand forever, the future is infinite, regardless of the future of the human race.
which means absolutley everything will happen at one point or not in the future.

nah...that isn't true...

1. the fact that the universe is expanding doesn't imply that the future is infinite at all. explain the logic there.

2. infinite time doesn't imply that EVERYTHING EVER will happen. there are 'different' infinities, with some expanding more rapidly than others. it's not a constant you can just throw around.

take the example of the infinite monkeys typing on infinite keyboards and eventually producing the complete words of shakespeare. assuming that these monkeys are really fast at typing (not infinitely fast mind you), within a given time period, say, one year, they'll have typed out everything that's possible to be typed right - hence it'll ******* shakespeare. now, what happens if you let them continue to type for another year. what will they type? everything has already been typed according to the theory...they'll only be repeating themselves. that implies that there's only a finite amount of stuff that can be typed which is incorrect. it's a paradox produced by making an incorrect assumption about infinity.

[Lie]

I figured this all out in college. I wrote it on a piece of paper and put it somewhere. I'll let you guys know if I find it.

Meanwhile you're all wasting your time typing all that shit out when you should be on Google looking for related Calvin and Hobbes strips to post.

[Andrew_Pakula]

Originally posted by Mathboy
Lets pull an example from popular fiction: In Star Trek IV (gotta have our geek cred in the picture, here) Scotty divulges to a scientist in a plexiglass factory the chemical formula for "Transparent Aluminum," commenting to McCoy "How do we know that he didn't invent the thing?"

Ignoring all of the other time travel junk that goes on in that movie, we can see a valid operation of this theory of time travel -- Even before he was born, Scotty was going to travel back in time to give away the formula to the scientist because it already happened -- that's how transparent aluminum was discovered. There are no branching future what ifs, that's just the way that it worked. Of course, there's an interesting uncaused causer in there -- where did the theory come from in the first place?

Another example of this is from Terminator 2.

It is explained that as a result of finding the chip and the arm of the first Terminator they were able to develop the technology which ultimately would lead to the create of them later on.

But if the existance of Terminators only becomes a reality because they found those 2 peices how exactly did it come to be in the first place? Just some devine creation out of nothing? It's a paradox.

Perhaps the new movie will explain further though because you would think that after destroying all the technology(blowing up the building and destroying the two peices) that would put an end to it all.

[dishpan]

the terminator films are probably the worst example you could choose to show how time travelling affects the past and future. theyre good movies, but if you tried to sit down and figure out the "paradoxes" youre nuts! they dont make any sense at all.

Originally posted by dishpan
the terminator films are probably the worst example you could choose to show how time travelling affects the past and future. theyre good movies, but if you tried to sit down and figure out the "paradoxes" youre nuts! they dont make any sense at all.

my view of the terminator flicks are this - its in John's message to Sarah- "The Future's Not Set - There's No Fate Then What We Make For Ourselves". so the future's not set and fluid but the past is - that's why John doesn't up and disappear at the end of T2.

works for me. *shrug*