Time Travel & Modern Physics

[Tangent 99]

I've skimmed some of the beginning but found it interesting and also I found it weird about the eye thing.

plato.stanford.edu/entries/time-travel-phys/

[Twitchmonkey]

Havent read it all yet but it sounds interesting seems like either they watched donnie darko or richard kelly read this

[¤(ø[¤-{cellar door}-¤]ø)¤]

[glow=red,2,300]Ah i see now philosophy has something to do with time travel because it's all linked up with one of the greatest philosophers of all time plato (for those of you who do not know he was as famous as socrates and questioned his theories) thankyou again much appreaciated[/glow]

[gabriel8616]

As my interest in time travel has been peaking, I have been reading many books and documents. There is one idea I have yet to see. Constantly we hear about the paradox one can create by killing ones younger self... or even in the case of "Back to the Future" coming in contact with ones future/past self. It would cause a catastophy. Consider this original theory I have independently developed. Let us define a time line. Point A is TODAY!... Point B is October 16, 1980. Now think about this, all point preceeding the current point are strictly defined by the events that occured during those times. IE... I was doing something spefic that day.. thus... If you define Primal Earth point B, it must be defined by what happened that day. In this case, I must conclude that one can not travel back in time, however, one my theoretically create a parrallel universe. I say this, because if I travel back to 1980, I exist twice, my older and younger self, however this will conflict with Primal Earth's point B, thus, we now have Earth 2. A parallel earth simply by your jump back. Future jumping is a little trickier and I haven't formally concluded anything of that yet, however, it would basically be the same by creating a parallel universe. Now, let's say we want to get back to Point A... the point we left Primal Earth. I would conclude this to be impossible because time is linear and constantly flowing... in PE, you went back in time, and time moves on, you are no longer there, you traveled back/forward. With this in mind, you may never again reach Primal Earth simply because ever jump you would be creating a totally different universe. So you see, if we consider this... I feel that we must reconsider the idea of "Time Travel" and go with the idea of "Universe Jumping." Those are my ideas, please reply!!! I would love input on how others feel on this logic.

[h4m]

are you basicly saying that when you travel through "time" you create a rangent univers? if you travel back in time what happens to the molecules that are at the point you travel back to? wouldnt they have to go somewhere? and if you went back in time instantly what would happen to the molecules since they would be in the same space as molecules in your body.. would it cause a nuclear blast caused by colliding particles or some catastrophic explosion?

[Bigboy]

Gab, your argument sounds like the Multiple Universes idea, which states that for each probabilistic event (or choice) a new universe is created for each possible outcome (like a branching tree). Going back in itme would be easier (just trace back down the branches of the tree), but going forward would be trickier, because you would be jumping past millions of probablilstic events/choices - so you wouldn't know which future/branch/universe you'd end up in.
In this model The Grandfather Paradox (the paradox one can create by killing ones younger self or ancestor) is no longer a paradox:

The white line is your 'original' history/timeline
A You make the choice to go back in time (follow the red line).
B A point in the 'past' where you appear. The fact that you chose to travel back to this point makes your appearance a probabilistic event, so a new branch/universe is created.
C You kill yourself/ancestor, but beacause you are on a different branch (universe) this is in fact an alternate version of you/your ancestor - your original history is unaffected (and cannot be affected) so no paradox.

In this model all theses branches/universes are alternate PU. You can think of a Donnie Darko TU as a cyst on one of the branches, which if not cured, will kill the whole tree.

[gabriel8616]

Thanx Bigboy, that is exactly what I had in mind. It just seems most probable to me that those are the constraints that we would undergo as far as time travel goes. So, it isnt really time travel, but more so, as it shows, an new possible outcome that we choose to undergo thus making a new universe in itself.

[h4m]

ok so its easy to go back then.. but is it easy to get back to your original universe? i mean i guess it depends on how much control you have over it.. but wouldnt your going back ot the original universe just make a new one?

[Bigboy]

Yep - EVERY decision creates a new alternate reality (universe). So upon returning you would make new universe.
So the new universe will be one where you went back in time and came back, whilst the others are ones where you didn't. What I'm driving at is, If the branching of the universe you are in is driven by your decisions then it can't be the 'wrong' one.

So as long as you return reasonably accuratly from the past to the point where you made the decision to go into the past, you should be on the correct branch - whichever one it is.

[h4m]

id still like to know this: if you travel through time and the effect is instantaneous then what happens to the molecules of air and such that you would warp into? wouldnt they be in the same place as molecules in your body?

[Bigboy]

Yes - if you just popped into existence at a given point in time then that would be a problem. Even air in this scenario would proabaly kill you. I suppose you'd have to design your time machine to create a you shaped vacuum for you to pop into just before you appear!

But the FTL and wormhole time travel ideas don't have that problem because in those models you never leave the continuous physical frame of the universe. (ie you dont pop in and out)

[Madridarko]

So continuing to use the tree/multiple universe example. If let's say instead of .. one question first when the branching universe that was created when an artifact travelled back in time, does the "Original Time line" up to the point when the time traveling object landed just dissappear or does it just stand there, or did it never even happen? (because some object travelled from Point A to B, and it branched off to Universe C, time between B and A or even passing A, does it just disappear or did it never even exist or is it just standing there.)


I will still be using the air molecules example. If let's say in point A, for some reason somehow 2 air molecules "go back in time" into point B, then the Universe will branch into the "Tangent Universe" (let's call it universe C) So from time span from Point B to the end of Universe C, there will be 4 air molecules that are the same exact matter (the 2 that came back in time and the ones that had already existed in Universe C) So let's apply that to donnie darko.. Let's suppose that instead of sending a jet engine he needs to send air molecules. (For picky people's sake, let them be Oxygen molecules) (I know that the Artifact has to be metal, but it's a hypothetical situation).
So donnie somehow gets the air molecules that travelled back in time and somehow sends them back to "original time line" Logically he will send them back to some timeline point a few seconds before point B because the time from B to A does not "exists" yet, but wouldn't that even creat another branching unstable Universe because from point B and all previous history prior to it, there is no missing "air particles" so this would also be a situation in which there are 4 exact same particles of matter.

Please correct any misunderstandings I have and if I am missing any info. of value to understand this problem.

[Phil]

This may be a bit off topic, but

Surely if you find a way to go back in time, no matter what you did, nothing would change.
Because whatever you do has already happened, so nothing would change.

[Bigboy]

Madrid:

when the branching universe that was created when an artifact travelled back in time, does the "Original Time line" up to the point when the time traveling object landed just dissappear or does it just stand there, or did it never even happen?

The 'original' universe (for wont of a better word) keeps going - just without the time travelling object.
The diagram above is extremely simplified - it shows just one instance. In a full diagram, there would be trillions of new branches every second for each possible outcome of each possible event in the universe - each of which would persist indefinately. The terms 'original', 'primary', 'tangent' don't really apply: you can never pin down 'which' universe you are in because they are so prolific.

I will still be using the air molecules example...

I think you have the wrong end of the stick here - our example of air molecules was asking the question: If you could time travel, when you do, what happens to the matter that occupies the space you suddenly fill when you appear?' and has nothing to do with any particlar time travel theory or DD.

In fact the whole conversation does not apply to DD (for reasons I have stated above), it's just a discussion about one possible nature of the universe.

(If I was going to be really picky I'd want to know which type of Oxygen molecule O,O₂ or O₃ )


Phil:
That is why the multiple universe model came about - it allows you to do all this stuff without invoking fate. In that model, yes the past is irrevokable, so when you travel back in time you create a new branch of spacetime in which future events have yet to occur.

[Madridarko]

Oh, so we are not applaying these theroies to DD? Maybe that is what I misunderstood. Thanks then.