Time Travel

[tsugomaru]

Just because time fits the definition of a "dimension", meaning it moves in a direction, doesn't mean it follows the rules of a "dimension". Time may not necessarily move back and forth as you said.

Don't fall into the classification trap where all you complain about is the semantics of a word or definition.

~Tsugomaru

[Bynary Fission]

Just because it logically follows does not mean it necessarily implies the truth, i.e logical fallacy. But time can be the fourth dimension depending on how you see it. I personally do, though not in a total spatial sense as the first, second, and third dimensions are. Time may not move like the other dimensions, but then again, the first dimension does not move like the third, yet that does not exclude it from being a spatial dimension. So why would the fourth dimension not be akin to the others that we know of?


~Bynary Fission

[devonin]

I'm pretty sure that the length of a plank of wood doesn't "move back and forth" and you can't, for example, travel backwards through width. Three-dimensional space is bounded in a way that Four-dimensional space wouldn't be, because time is functionally the extension of all three dimensions across a duration.

It's the only one you could move around in, because we percieve the world as a long series of individual "slices" of time in which three-dimensional space operates pretty much exactly how we think it ought to, mostly staticly.

You can follow a river upstream, or downstream, or stay in one place and watch the water travel past. But even though the water is moving, a given part of the river is "still" and just has water moving past it instant by instant. You can pick up a stick that is floating in the water, and put it back in upstream, and it will flow past the same area again, but you can't pick up "the river" and move it somewhere else.

[Bynary Fission]

Yes, spatial dimensions operate in a way that we move and interact with. We exist in "time", just like the river analogy you mentioned about water always being still. But as we move about or stand still, we still pass through time as an abstract concept. It surrounds all things. So perhaps dimensions beyond that of the third exist in a radically different way that we don't yet know of, same with states of matter. First, second, and third dimensions. Solid, liquid, gas. Seems simple enough? Ah, but there are also plasmas and Bose-Einstein condensates. These states of matter are nothing like the three states of matter that we are most familiar of, just as the fourth dimension might be much different from the three spatial dimensions.


~Bynary Fission

[emo-carly-ffr]

The way my friend describes it for me. Is that time travel is stacked in layers one on top of the other.
so thats why its nearly impossible to go back in time because there is layers on top of it
get what I'm sayin?

[Mr.Nothing]

Time Travel is impossible.

P.S. Time is basically just a way for humans to say when the sun rises and sets.

[devonin]

You might want to qualify your statement a little there, perhaps with reasons, or evidence, or logic.

We're discussing the possible consequences of time travel if it were possible, not just trying to decide if it were possible. Clearly it isn't possible by our current understanding of science, but that doesn't mean it never will be.


As for your postscript. I would argue that time exists because there are things that are not happening at this exact moment, so there must be some context for describing when they happened. Things that happened before this instant happened some number of instants ago. That's time.

Our labels of time are entirely subjective. Time doesn't use days and hours and minutes, we do, but that doesn't mean that time doesn't exist outside of our labels.

A tree is present objectively regardless of whether we acknolwedge that it is there, or what term we choose to apply to it.

[tsugomaru]

What says that the time can move back and forth in the first place. I suggested that time may not necessarily be like the other three dimensions in that it can move in many directions. Time may just be one straight forward thing, continuously moving in the same direction. You can classify time as the fourth dimension, but classifying it as a dimension doesn't mean it has to follow the definition of a dimension.

You have no evidence that time can move back and forth, while my idea of time is the currently accepted idea of the movement of time. You can't say yours is any more right until you prove me wrong and I can't say yours is any more wrong than mine without presenting proof.

~Tsugomaru

[Adamaja456]

Ok, so once again i was watching an episode of The Universe, Unexplained; and one of the questions that came up was time travel.

I guess there is a guy thats trying to make a small time travel device that can send photons or small atoms through time. The way he explained time travel and his opinions on it seemed logical in my eyes, so i'm leaning more toward agreeing with him. He stated that you can only travel back in time to the day you invented a time machine. If you go back any farther, the time machine wouldn't of been invented it.

And to disprove that grandfather paradox, he suggests parallel universes so when you go back in time, it might not be the universe that you're accustomed too. Everything might be almost identical but its not "your" universe so when you kill your grandfather, he dies but nothing happens to you.

So i think time travel is a possibility in the future. I'm just not sure how scientists will use it.

[devonin]

That's one of the usual ways to dodge out of the potential for a paradox in terms of modifying the time continuum, but frankly what he describes isn't a time travel device, but instead is a parallel-universe-travelling device.

[rzr]

Warping space is different from time travel, though hardly. I believe I saw the episode you're talking about, its complex to explain. But his theory does make sense.
He says you would be unable to travel back to before the machine existed because there would be nothing to put you back into, and nothing to send you back to your time period. Though in theory, if a hand-help time travelling device was taken back in time when person x went back, they would then be able to return to their own time period.

[Bynary Fission]

Unless you're traveling down the time continuum in the same way a car moves on a road (i.e at a constant rate on a linear path), then you wouldn't be stopped, because you would simply materialize into any time you wanted. However, getting back would be an issue, unless your machine went with you.


~Bynary Fission

[Verruckter]

Originally Posted by devonin

You might want to qualify your statement a little there, perhaps with reasons, or evidence, or logic.

We're discussing the possible consequences of time travel if it were possible, not just trying to decide if it were possible. Clearly it isn't possible by our current understanding of science, but that doesn't mean it never will be.


As for your postscript. I would argue that time exists because there are things that are not happening at this exact moment, so there must be some context for describing when they happened. Things that happened before this instant happened some number of instants ago. That's time.

Our labels of time are entirely subjective. Time doesn't use days and hours and minutes, we do, but that doesn't mean that time doesn't exist outside of our labels.

A tree is present objectively regardless of whether we acknolwedge that it is there, or what term we choose to apply to it.

Well, he's actually right. Time does not actually exist. It is just an image used to describe something that is far more complex. But in reality, it's not. Things aren't the same they were one hour, one minute, one second ago. But this energy, flow or whatever you might want to call it is not empirical. You cannot measure time, you cannot touch it, nor feel it, and it does not bend, twist nor turn.

The concept of time can be misleading because it "affects" everything. But in reality, it's only universal because it so happens that nothing can stay the same forever. The way molecules and atoms are built, it is absolutely impossible for something to stay exactly the same. They will degrade as "time" goes by. And since we observe this phenomenon on every single thing constituting our own universe, we conclude that all these individual cases are bound by a single force: time.

In reality, the only possible way of going back in time would be to "fix" every single atom and molecule the way it was a few minutes ago. But of course, that is impossible.

So, in fact, if you wanted to go in a "separate" version of reality, where, for example you invented something as a kid that made you a wealthy man years later (thank you thetenthdimension.com), it would be impossible because there would be no such alternate reality: the only possible one would be the one where you didn't make such an invention.

[rzr]

Like I just said, inventing a sister machine, this one portable. Like a game boy and an N64. If you don't get that analogy, I'm sure as hell not explaining it to you.

But you would have to be travelling in a parallel universe. If you change something in your universe you would disrupt the future [in theory].
However, travelling in a parallel universe would be dangerous as everything in it would be the exact opposite, making time travel an impossibility in that universe. Unless of course we're the parallel universe, in which case that makes time travel virtually impossible for us.

[Rad3n]

I heard a theory that should you travel back in time; You wouldn't be able to make any actions which would affect the future. *A sort of defence mechanism created by the laws of physics*. But by my reasoning that would mean that the moment you attempted to travel back in time you would cease to exist... Kinda pointless discussing a paradox though .

*don't flame me or quote me for incorrect use of the laws of physics*...please, It wasn't my theory.

Sorry I can't tell you where I heard it or send a link (it was on TV).

[rzr]

I don't understand how that would work. I mean, physics hardly control your actions to begin with. And by actions I mean what you think. If I thought "oh, I don't want to make that mistake again" after I travel back to a week ago today, then I don't DO the action.
Which is contrary to your theory saying that I have to DO the action.

[xinpig]

Time travel and chaos theory go hand in hand on this one. if you change the past you will change the past for that branch of time. that would not affect the path of time you left your friends in. if you did change the past you would be never able to go back to the future that you left behind. and plus how could you go back to a time before your machine even existed? it would be improbable and not to mention the amount of energy required to bend and tear space-time would be of highly enormus cost and the payoff in the end would hardly be worth it to the future that that person left because if they changed history even a tiny bit they would not be able to go back to the correct future.

[rzr]

Nonetheless the theory is obviously incorrect. It only states that if you DO something that physics will not allow it to happen. But what if it's something I DON'T do that I did in the past? Eh?

[devonin]

Also I'm not exactly convinced that "physics" is a motive force capable of taking an active intervention to prevent something from happening. What are you saying? If you would create a temporal paradox you simply poof out of existence? Because of what?

[The Dragon Knight]

Originally Posted by devonin

It's the only one you could move around in, because we percieve the world as a long series of individual "slices" of time in which three-dimensional space operates pretty much exactly how we think it ought to, mostly staticly.

If we believe time to be "slices", as you put it, then shouldn't we theoretically be able to move the slices around, or maybe even erase them altogether?