"The future ain't what it used to be."

time travel questions



hi! sorry i am new to this kind of stuff and i dont understand some of the concepts... the questions i ask below maybe a little bit trivial to regular users but i hope someone can answer my questions.. thanks
1.) in the multiverse scenario, are we sure that we can get back the the same future that we came from but not some other possible futures? if there are an infinite number of possible futures, we may end up in a future that looks really like ours but not exactly the same one..is it true? if it is so, how can the ppl in the future that the experiment is conducted be sure that it works coz they can never get the response? there may be an infinite no. of the universe same as ours and there may be 5-6 responses in one "same" universe and some other may get none. then it may end up that there are 6 of the same person in the same universe at the same time and none at the universe where 5 of them came from.( or maybe 6 coz maybe all 6 of them didnt came from this one)
2.)if we can travel back in time.. are we sure that we will arrive in our past but not other possible pasts? if we can .. then thats fine.. but if we can't.. then how can we be sure that it is safe to travel back? if we end up in a universe that is not expanding but contracting, then what will happen?
3.) same as above.. how can we be sure that we will arrive in our future but not other possible futures? since the world is chaotic, then we can't predict how our future will be and thus unable to prove that the future we travel to is really our future but not other possible futures.. is this true?
4.)if a parallel universe is created as a result of a time travel...does it mean that all the past in that new universe before the time traveller arrive is the same as the past where the time traveller came from? or does that new universe not have a past before the point of time when the traveller arrives? if it does have a past... so that new universe is also created by a similar big bang as the original one..is it true? then is that universe created by a big bang? or by the time travel? or both?
5.) is it possible that our universe is also a product a time travel?
6.) if 5.) is true, is it true to say that the possibility we have a time traveller again is 0? my point of view is.. if 5.) is true.. and if we can creat a time machine b4 the world ends, then that machine will only travel to a new universe it creates but not this one coz this one is created by another one earlier. even if we can travel to a particular past of future by pin point accuracy..the possibility that we get a time traveller is still 0 coz there may be an infinite number of universe similar or even the same as this one.

sorry..my grammar is not that good .. hope my questions are clear enough and somebody would spare some time to answer them... thanks!
Welcome. Such questions are never trivial - they're fundamental to what this board's all about. Here are my answers - although no doubt others will disagree:

1) In fact, in the multiverse scenario you could never get back to your original universe - just one extremely similar to it. And you would never know.

2) Depends what type of time travel you're doing - multiverse, predetermined, what.

3) Well, if you just sit there you're travelling into the future. You can 'speed it up' by moving fast, or sitting in a gravity well - by none of these methods do you actually switch universes.

4) Who knows? Since noone's ever done it, it's a moot point.

5) Well, what would the travellers have come to, to start us going? the empty nothingness of the timeless pre-everything? I prefer the 'random quantum fluctuation' bit myself.

6) I see what you're saying... If the multiverse idea is right, all sorts of things like this pop up. If fact, there'd be some universe somewhere in which everything happened - one time traveller, multiple time travellers - no humans - they all would have happened.