Time Travel

[devonin]

Re: Time Travel

In fact it seems to me that it is an absolute necessity to conclude that if time travel is invented at some point, that at some point further up the timeline, a regulatory force would have been created. It is pretty much the only way to reconcile our continued existance with the concept of time travel.

Once it can happen, it can happen at all future points, and it seems inevitable that a suitably enlightened culture would eventually develop to manage the effects of previous tampering with the timeline.

[Shenlon]

Re: Time Travel

Enter the simpleton.

So I'm a failure at math. My concept of physics starts with p and ends with s. I'm dimly aware of gravity and only as a mysterious blockade to my fantasies. You get the picture.

The way I see it (which, other than being unqualified - though that case can be argued for all of our posts... we'll say I'm <i> more </i> unqualified than the rest of you, may ignore certain truths that scientists have long established to govern our world) time travel may or may not be possible. Theoretically, sure, physically? We'll only ever find out if it's developed in our lifetimes.

Give me a minute while I try to remember the original post because reading what everyone had to say gave me quite the headache. Alright, I can't...so I'll go with my gut instinct.

If we’ve established that time travel can only be possible from the point of creation of a time traveling machine onwards, I think the nature of reality would change, regardless of how it is used or for what purposes, if ever. I don’t know why I think this, I just do.

Anyways.

Like many of you have said, if someone goes back in time to change anything, no one will notice because our history will never have changed. A person can only perceive what is happening. They can anticipate the future and study the past, sure - but that’s another topic. If what has happened changed all of a sudden, they cannot perceive the change because they were simply not there. Say Hitler won the war. And we were living in blimps. And the world was a utopia. And we were all golden haired, blue eyed super-humans. It’s not like we’d know about this OTHER life we once had. That is our history, that is our life. Plain and simple.

Say you go back to save your friend bob. I’m inclined to agree with devonin on pretty much everything he has said because it makes the most sense to me. You can’t. How could you? If you did you would never know he was in danger in the first place. Unless of course a) by doing so you have nullified your current existence of knowing he had died, thereby ending everything about you while another copy of you exists in place. A copy that is none the wiser your buddy bob had ever been in danger. 

Or maybe you succeed, but then I think the world you would go back to would be the same. Any actions you may have caused in the past will start a tangent timeline. Alternate universes - sure, whatever you’d like to call ‘em. Therefore in your own timeline bob, clearly your best friend ever, would still be dead. The way I see it a cause cannot also be the effect. I know there are exceptions to this but if I went back to kill my grandfather, of course I’d cease to exist. But not because I killed him, but because I cannot exist in the new world I have created for reasons i’ve already mentioned. Or I go back to my own world where he was still my grandfather and in an alternate world I will have never existed. (Like that does me any good.)

Now I think to take that to the extreme time travel may be possible but not /possible/ unless in a purely observational capacity. Why? Because the moment you are in the past you are changing it. It may write you out instantaneously or nothing you do will have an affect on your own timeline. The only way around that would be if you could be in a sort of ‘limbo’ but I don’t know the physics of that being possible.

As for the future... well gosh darnit you guys are the experts and everything I say may in fact be thoroughly debunked. In that case, I hate all of you. If not, maybe if we get to talking about the future I’ll come up with some ideas of my (mathematically-challenged) own.

[devonin]

Re: Time Travel

The idea that time travel would necessarily involve moving both through linear time and non-linearly into an alternate universe is generally one of the "easy way out" explanations of time travel. Quantum mechanics in the Copenhagen Interpretation denies that such a thing could be possible, but MWI the Many Worlds Interpretation is one of the farily well regarded alternatives.

I'm generally apt to go with the MWI myself, all things being equal, because I both find the idea fascinating and it actually creates a form of determinism that I find really intriguing to think about.

I mean, most of what I've said here has just been a philosophical attempt to remove the casuality paradox being described by others, but as has been noted, we have no real way to predict what the actual consequences of time travel might be.

[Shenlon]

Re: Time Travel

Alas, the problem with thought experiments embedded in grandeur.

[devonin]

Re: Time Travel

Embedded in grandeur? Mind explaining that one a little bit?

[Shenlon]

Re: Time Travel

That was me being a little tongue-in-cheek. I guess what I meant was a high-concept discussion easy to discuss but impossible to reach any strong conclusion towards.

Hope that settles it.

[tsugomaru]

Re: Time Travel

It is my belief time travel to the past is impossible because by doing so, you are bringing yourself back to a spot in time and by just being there, you would have changed the "past", making it your present. However, time travel to the future might be possible, although returning back to the "present" would be difficult. Why? My view on time travel is moving every single atom in the area where you want to "reverse" time back to where it used to be or will be.

I don't think we can time travel like we do in the movies.

~Tsugomaru

[ballaw hare]

Re: Time Travel

It is my belief time travel to the past is impossible because by doing so, you are bringing yourself back to a spot in time and by just being there, you would have changed the "past", making it your present. However, time travel to the future might be possible, although returning back to the "present" would be difficult. Why? My view on time travel is moving every single atom in the area where you want to "reverse" time back to where it used to be or will be.

I don't think we can time travel like we do in the movies.

~Tsugomaru

Ya I agree, rewinding all the atoms in the universe would be pretty difficult, especially the ones that went into black holes or just disappeared completely like matter sometimes does. This is the point I get confused on the most, a lot of physicists say that time might be the 4th dimension, but that makes it so abstract. Isn't time just movement? If nothing moved would time still pass?

[devonin]

Re: Time Travel

I'd argue that time is a linear dimension just as length, width and depth are.

If you imagine a three-dimensional object, it has a measurable length, width and depth, and also extends physically backwards through time to the moment of its creation.

What you'd get is a long chain object like &&&&&&&&&&&&&& representing it's entire time existing. What we percive of an object is it's length, width, depth, and a slice of it's time at the moment we observe it.

[Bynary Fission]

Re: Time Travel

Time is logically, the fourth dimension, and whether you view it as spatial or not is up to your perception of time.

When you move across the first dimension, you move in one direction. In the second dimension, you move across two (length and width). In the third dimension, you move across depth, width, and length. In the fourth dimension, you move through width, length, depth, and time. When you move, time passes. You are passing through time. Therefore, it is logically a dimension, and it can be seen as spatial or non spatial (spatial being that it encompasses everything, and you move through it no matter what), or non spatial (It's not like depth, length, or width, but you still traverse through it). Maybe time does not have tangible dimensions...or does it? Mathematics were not meant to encompass time. Perhaps it can be adapted to find the coordinates of time.

~Bynary Fission

[tsugomaru]

Re: Time Travel

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]

Re: Time Travel

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]

Re: Time Travel

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]

Re: Time Travel

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]

Re: Time Travel

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?