Time Travel and Paradoxes

[fafalone]

We don't know yet.

[Ami]

ok, maybe i'm just not getting this.. i can see how one would travel into the future, traveling faster than the speed of light, but for paradoxes to occur, you have to go back and change the past, how would you travel into the past? it doesn't make since to travel faster than light backwards, you would move in a different direction wouldn't you?? or am I just carzy.....

[fafalone]

As your velocity approaches the speed of light, time slows down, and if you exceeded the speed of light you would in theory travel into the past. Travelling into the future would involve travelling extremely close to the speed of light.

[Ami]

ok..

[Katie]

That makes sense, I never thought of it that way before... However, I believe it would be impossible for a person to change the past, because even 'a butterfly beating its wings in China can cause a tornado across the world'... We would be mere observers of events, and it's even possible that the people in the past would be unaware of our presence.

On the other hand, what if at some point, travel into the past becomes so regular that the future would only be the way it is because of our alterations to the past? I'd rather believe in my first thought, but I can't say which would occur...

[fafalone]

The present is the way it is because of the future; everything that has happened is the result of everything that will happen; therefore if you travel into the past and change something, it will always have happened and a different future never would have existed. This idea comes from the concept that if you can travel into the past, you should be able to travel into the future, and this makes time a closed cycle whereby all event are the way they are because of everything that happened in the past AND future.

[Katie]

In that case, do you believe that just because we haven't gotten to the future yet, that people exist there who may be traveling back in time (to our time, or before it, or after it) to alter things? A closed cycle linking past and future-if it's true, is time then truly the "fourth dimension," able to move backwards and forwards upon itself?

 

Just because we don't understand something doesn't mean it doesn't exist, and while I'm not convinced that we are capable of time travel, I'm not convinced that it doesn't exist either.

 

What about all the possible futures-forgive me for sounding cliche science fictional here-but are there "other dimensions" where might have beens have happened? Is that less likely than the possibility that our present depends on a past that can be/has been changed by a future that's already occurred?

[tomgwyther]

Time is just natures way of stopping everything happening at once!

 

We don't realy have any proof that time flows from past to future, only that events happen at different pionts in spacetime. This collection of events are what we call time.

 

Consider this:- Winston Churchill is sat in his office in London wondering which way the war will go, At this piont he belives anything could happen and that he has complete free will.

 

We in the future on the other hand (If we could go back in time and visit him) know exactly what's going to happen, down to the last detail. We could tell him everything thats going to happen, with precise acuracy, even what he was going to have for breakfast next week!

He wouldn't be able to change any of it.

 

In the same way, someone in the future could know exactly whats going to happen to you or I, having read it in a text book. we wouldn't be able to change it because we havn't experienced those events yet, but the future guy could easily tell us what we're going to be eating next week.

 

Changing the future is as impossible as changing the past. Events past and present are have or will have happend events. Even if you did have a time machine, If you went back in time to try and change somthing, the event of you going back would always have been there anyway.

[AI_Interface]

Tomgwyther, you seem to be in the determinist camp when it comes to time. Here is a simple thought experiment:

 

Let's say I've just completed a marvolous time machine that has the ability to travel into both the past and the future. I'am about to step through the time machine to find out the winning lottery number for next weeks draw when suddenly 'I' walk out the door of my time machine with a piece of paper that has the lottery number written on it. Sure enough the next week I win the jackpot and proceed to go back in time to give 'myself ' the lottery number but instead I decide to play a trick.

 

Instead of writting the correct lottery number on the slip of paper I give to 'myself' i write the wrong one. I then proceed to the past and give the slip of paper to 'myself' using different wording then I remember 'myself' using. It would appear that I've quite effectivly changed the past.

[tomgwyther]

You would have given your past self the wrong lottery numbers and would have won nothing

 

... You would have seemed to have changed the past as you know it, but only because you had extensive knowledge of the future. but then that's what you were going to do anyway.

 

One thing I failed to mention in my orgional statement was that; if you have precise knowledge of what we call 'the future' then you can indeed appear to change it... it would seem as though you'd changed it. but actually it was have going to have happened anyway.

 

OR (If everything was 'sunshine and lolly-pops!')

 

If you have precise knowledge of the future then you would change it in your own reality, but then there would be another reality running parallel to your own but both would be unaware of each others existance.

 

Unfortunatly, neither of us has a time machine to test these two theories out!

---Absolute fixed causality

(Sounds a bit depresing but still most likely)

---Two bodies sharing the same space and time but unaware of each others existance

(Sounds like my parents in bed!)

 

p.s. I've spent ten years reading temperal mechanics, Quantum mechanics, special and general relativity, and it all made perfect sense; I had it figured out until you posted your causality paradox!!! I guess I'd better do some hard-core thinking!

 

P.P.S. it's good to lock horns with a similar interlect.... thanks

 

Tom

[AI_Interface]

You would have given your past self the wrong lottery numbers and would have won nothing

 

... You would have seemed to have changed the past as you know it' date=' but only because you had extensive knowledge of the future. but then that's what you were going to do anyway.[/quote']

If that's what I was going to do anyway then why didn't I give 'myself' the wrong number in the first place? In which case I would want to give 'myself' the real number when I went back in time. That is the heart of this paradox; do I win the lottery or not?

One thing I failed to mention in my orgional statement was that; if you have precise knowledge of what we call 'the future' then you can indeed appear to change it... it would seem as though you'd changed it. but actually it was have going to have happened anyway.

Does that mean that the information that you had was false? Where did the false information come from? Information can't come from nothing.

If you have precise knowledge of the future then you would change it in your own reality, but then there would be another reality running parallel to your own but both would be unaware of each others existance.

I think you mean that there would now be two realities where there was one. The idea of multiple universes is an intriguing one and can lend support to both determinism and free will arguments (it also has a excellent track record for solving time travel paradoxes like the one I described).

 

Take the lottery number paradox, using the theory that there are multiple universes with different paths through spacetime, we can infer that I won the lottery in a universe and in another, lost. In other words you could say that in a few universes it was 'determined' that I would win the lottery but in other that I would lose. Of course then you have to deal with the case of how the behavior of a person in another universe ('me' choosing to travel back in time to 'my' universe) would affect causality in another universe.

 

The best explanation in my opinion is that the past, present and future are meaningless distinctions. When you seem to travel forward in time, you are merely travelling to another, extremely simillar universe. Thus instead of use 'moving' through time we 'move' through different universes.

Unfortunatly, neither of us has a time machine to test these two theories out!

Very unfortunatly.

---Absolute fixed causality

(Sounds a bit depresing but still most likely)

---Two bodies sharing the same space and time but unaware of each others existance

(Sounds like my parents in bed!)

I don't think that determinism is depressing since then I would know that the future isn't uncertain and that if something happens I don't have to regret it because it couldn't have happened any other way. I'm only interested in which theory is logically consitent and consistent with empirical evidence.

 

p.s. I've spent ten years reading temperal mechanics, Quantum mechanics, special and general relativity, and it all made perfect sense; I had it figured out until you posted your causality paradox!!! I guess I'd better do some hard-core thinking!

I suggest you read "The Fabric of Reality" by David Deutsh and "Hyperspace" by Michio Kaku. Both books have a lot about parallel universes and the nature of time.

 

P.P.S. it's good to lock horns with a similar interlect.... thanks

Same here.

[reyam200]

since your talking about time paradoxes, ill post here. would da ja vu have anything to do with this.

(da ja vu is feeling like your repeating a event.)

say if you changed a event once , and later stopped you self from going back the first time thus making it go on as it did first. would you experince da ja vu in the event you changed(and stopped the change)? or would it go on normal.

i have knowledge on this subject but some of it i still can't understand.

[AI_Interface]

since your talking about time paradoxes' date=' ill post here. would da ja vu have anything to do with this.

(da ja vu is feeling like your repeating a event.)

say if you changed a event once , and later stopped you self from going back the first time thus making it go on as it did first. would you experince da ja vu in the event you changed(and stopped the change)? or would it go on normal.

i have knowledge on this subject but some of it i still can't understand.[/quote']

deja vu is completly unrelated to time travel. There is a perfectecly good psychological explanation: let's say you were walking down teh rode and you mind was wondering and you glanced at a stop sign that was still a ways ahead of you. Then you arrive at the stop sign and snap back into a more focused mode and voila it seems as though you've been there before. It has to do with your unconsious mind registering somthing while consiously you ignore it and then you don't.

[reyam200]

oh

ok

thanks for answering my question.