Time Travel - Is it possible?

[soon2bepro]

SammyKid11 wrote:

- many scientists tell us time travel is absolutely
- impossible...I don't know whether or not that's true

Ok, I will try to explain this from my point of view (Scientifical, deterministic. I'm open to discussion as long as the goal is to come to conclusions through logical reasoning)

Time is often defined as movement. I'd say time is measured in events (we could argue that some events could not include movement, but i'm not going to get into that).

If we think of the universe as an immense variety of things ("factors") that interrelate with each other creating events, which then in turn affect other "factors", making a chain of cause-effect-cause, we can easily picture time as a line that follows a path.

The question of time travel is wether we can jump backwards or forward in this line. Now, let's think about this. The line does not create parallel realities for each point of itself (at least there's no evidence of this), so how could we "jump" to something that isn't there?

Well, we would have to be able to control this line. If we can somehow step aside from this line, then make it go forward, we'd end up in the future. If we could make it go backwards, we'd end up in the past. Now try to realize what this means. We would have to alter the very basis of the universal law(s). Not just the ones we know about now, but the whole thing. Whatever makes the universe work the way it does, we'd have to control it. We'd then make the whole universe run forward or backwards as we pleased. Seems kinda hard, especially taking in account that we're part of the factors in this universe, meaning we're still affected by innumerable effects. So we'd have to be able to step aside, somehow (either by finding a different reality or by "creating" one. Creating as in making some sort of device where the universal laws do not apply).

Now, something much more realistic than that, is to try to "live" longer. Or rather pospone your life.
We're part of this reality, and we exist in different stages of it's timeline (wether it's arguable that we're not the same person at all times but that's irrelevant here).
But living a long life is really not what this point is about, since then it could be argued that all people travel in time. But that's not what we're seeking, we're seeking to somehow "beat" the time line, in a way. Either moving backwards in time, or moving forward faster than real time.

But this last option is really a matter of perspective. It's totally arguable that if you're in a non-concious comma for 5 years, you'll wake up and feel the same as if you were transported in time 5 years ahead (other than aging and other complications of course).

So, instead of trying to alter the whole universe, we could easily try to alter ourselves in order to make more time seem less to us (or BE less to us).

For example:
Studies suggest that objects moving at greater speeds tend to "go slower" in matter of time. If this was the case, we could for example just travel around in circles at high speed for a while, and then return to our daily reality. Maybe a year of real time would be 9 months for us, or whatever.

Another example that has been suggested is stasis, such as freezing or something like that. It hasn't been proved that someone can survive any sort of stasis, but maybe sometime in the future /images/graemlins/smile.gif

Now, moving backwards is a whole new different thing. Time only moves in one direction, so this "evasion" isn't going to help. In order to move backwards, we would have to do what was suggested at the beginning of this post. To control time.

But let's suppose we can do that. Let's say we can make the whole universe run backwards to some desired point without us being affected. Now let's say we want to get back to "our" time. How would we do this? We would have to make the whole universe run forward again (or use some of the other tricks suggested here, such as stasis or w/e). What makes people think they'll be back and find the same reality (plus small changes that they intended)?

It's rather ridiculous to assume that the events you produced didn't result in a whole new different reality, especially if you went back a lot of time (like in the movies). The only alternative here is to assume that since we can control time, we understand the universe so much that can fairly calculate all the chain reaction back to our point and decide that no major change would be done by our interfering (or rather make the particular changes we want, without altering anything else). There's an episode of "the simpson" where homer goes back in time and tries not to produce any major changes. It's pretty hilarious, though completely ridiculous obv /images/graemlins/smile.gif

Anyway, I'm getting out of the topic. I just wanted to let people know how I thought about this issue. I was always fascinated by this idea as a teen, mostly from movies. Though I always found fundamental errors in them. Not 6 months ago I watched "timecop" and that was it. I couldn't stand so many argumental mistakes so I had to give the issue some thought.

That's all for now... Have fun
And try not to think too much /images/graemlins/wink.gif

[Borodog]

Without resorting to any physics or metaphysics, I tend to think that time travel is impossible by answering this question:

Where are all the time travellers?

[mostsmooth]

[ QUOTE ]
Without resorting to any physics or metaphysics, I tend to think that time travel is impossible by answering this question:

Where are all the time travellers?

[/ QUOTE ]
some folks theorize you cant travel back in time to a point piror to the discovery/invention of time travel which would answer your question

[Matt R.]

Time travel is theoretically possible. I'm not a physicist, only a student, and I don't know the exact details (I haven't studied general relativity in detail), but I've heard of two ways in which moving backwards in time is possible.

The first is by using a Kerr black hole, which is a rotating black hole. If you go beyond the event horizon... meaning you can't get back out, so it's not exactly practical... and move in the same (I think?) direction of the black hole's rotation, you will effectively move back in time. Without knowing any of the tensor calculus for gr, I would think that this is due to a combination of the enormous gravitational effects of the black hole and the radial acceleration you are undergoing as you rotate around the black hole. This would of course require the technology to manipulate black holes, which may never be possible, but according to Einstein's equations it is theoretically possible.

The 2nd way is to take a rigid rod which is rotating at a tangential velocity close to the speed of light, and walk along the surfuce in the direction of rotation.

These are just theoretical exercises though, and would obviously require a huge leap in technology to have any hope to put these possibilities to use.

[soon2bepro]

That is a very good point borodog, though you could theorize that this is the "real" timeline and we still haven't got to time travel capability.

However, your point assumes that people with the capacity of time travelling would reveal themselves. For all we know, they could be as powerful as what we think of "God" nowadays, if they could control the universal law(s) in such a way. There is no reason to believe that this reality was or wasn't affected by time travellers, so your argument is rather flawed, though very interesting.

mostmooth: That is the most ridiculous thing I've ever heard about time travelling. Where is the reasoning that leads to the idea that this capacity is bound in some way like that?

It seems to me like it's the kind of "theory" that people who want to prove something is true (rather than trying to find out if it is) would come up with.

I've been thinking ahead about what you'll come up with, and even in my wildest dreams I can't come up with a good argument to sutain such an idea.

Matt R: I haven't heard anything like this before. I can't argument anything about these since i'm not a physician myself. But let me just say that it sounds rather unreal.

However, I don't expect anthing to be drawn from that comment I just made. Hopefully someone else with more knowledge in the subject will give their opinion about this matter.

[mostsmooth]

[ QUOTE ]
mostmooth: That is the most ridiculous thing I've ever heard about time travelling. Where is the reasoning that leads to the idea that this capacity is bound in some way like that?

It seems to me like it's the kind of "theory" that people who want to prove something is true (rather than trying to find out if it is) would come up with.

I've been thinking ahead about what you'll come up with, and even in my wildest dreams I can't come up with a good argument to sutain such an idea.

[/ QUOTE ]
where did i say it was my theory?

[Borodog]

[ QUOTE ]
That is a very good point borodog, though you could theorize that this is the "real" timeline and we still haven't got to time travel capability.

[/ QUOTE ]

If there is only one "timeline" that is mutable, then I think we should be lousy with time travellers if they will ever exist. If travelling in time splits and creates new timelines, then I would think that the probability that ours is the "original" (if that has any meaning in the presence of time travel, which I doubt) would be vanishingly small, so we should again be lousy with time travellers. That we are not then leads me to think that it is probable that time travel is, and forever will be, impossible.

[ QUOTE ]
However, your point assumes that people with the capacity of time travelling would reveal themselves. For all we know, they could be as powerful as what we think of "God" nowadays, if they could control the universal law(s) in such a way. There is no reason to believe that this reality was or wasn't affected by time travellers, so your argument is rather flawed, though very interesting.

[/ QUOTE ]

Anything's possible. It seems to me if there were time travellers from the future there would be temporal "cruise ships" "docking" in New York on a daily basis, like cruise ships dock in the Bahamas. Time tourism seems like it would be a lucrative business.

One of the authors that I think treats time travel in a fascinating and believable way is Dr. John Kessel (http://www.amazon.com/gp/product/B000C4SNA8/qid=1136223041/sr=2-2/ref=pd_bbs_b_2_2/103-8484132-5162210?s=books&v=glance&n=283155). I took many writing classes under him in grad school, and I highly recommend him. His time travel short stories are also fantastic (e.g. The Miracle of Ivar Avenue).

[soon2bepro]

mostmooth: I didn't say that either /images/graemlins/wink.gif I was just argumenting against the idea, not you.

borodog: I didn't mean that when I said this was the "real" timeline. As I said there is no evidence that alternate realities are there for each point in the line, much less that the line "splits" creating alternate realities like in back to the future. That is a pretty hilarious assumption btw /images/graemlins/smile.gif

However, what I meant was that in order for time travelling to be invented by humans (or someone/something else), the time line would have to reach a point when that happens. Now, until that point, the timeline has been running normally, as it always will. But until that time, there are no time-travellers. I was just saying that we can't know for sure if time has reached that time and then they made it go backwards or what.
Your point is that, if time-travelling is possible, where are the time travellers? I think a better point would be: If time travelling is possible, how do we know that everything we know of wasn't influenced by time travellers?

If you note the difference, you'll see that in your questioning you're assuming that the present must have been influenced by time travellers if they are to ever exist. Well, for that to be correct, you'd have to assume that there ARE alternate realities for each point of the timeline. Like, right now there is an alternate reality for yesterdary, one for tomorrow, one for 10 years from now, and one for a zillion years from now. If that was the case, then your theory that "if time travelling was possible and would be done in some point, it has already happened", would be right. But there is no reason to assume that this *multiple realities for each point in the timeline* thing exists.

Even more, you ask "where are the time travellers"

You say time travellers would be docking in the bahamas or w/e... You talk about lucrative business! That's just nonsense to assume all that /images/graemlins/smile.gif

I don't think you were serious about that so I'll just skip replying to it for now.

[Borodog]

[ QUOTE ]
borodog: I didn't mean that when I said this was the "real" timeline. As I said there is no evidence that alternate realities are there for each point in the line, much less that the line "splits" creating alternate realities like in back to the future. That is a pretty hilarious assumption btw /images/graemlins/smile.gif

[/ QUOTE ]

Why is it hilarious? The Many Worlds Intepretation (MWI) is one of two common interpretations of Quantum Mechanics (the other being the Copenhagen Interpretation; i.e. wave function collapse). In many ways I find MWI to be the simpler and more elegant of the two, which given that the laws of nature usually tend to be simple and elegant, I find to be very appealing (although that doesn't prove that the MWI is correct, of course).

[ QUOTE ]
However, what I meant was that in order for time travelling to be invented by humans (or someone/something else), the time line would have to reach a point when that happens. Now, until that point, the timeline has been running normally, as it always will. But until that time, there are no time-travellers. I was just saying that we can't know for sure if time has reached that time and then they made it go backwards or what.

[/ QUOTE ]

It shouldn't matter if it hasn't been invented yet. My point is that if time travel is invented in the future, surely traveling into the past will become a popular passtime. So, where are all the time tourists?

[ QUOTE ]
Your point is that, if time-travelling is possible, where are the time travellers? I think a better point would be: If time travelling is possible, how do we know that everything we know of wasn't influenced by time travellers?

[/ QUOTE ]

I don't see why that's a better question.

[ QUOTE ]
If you note the difference, you'll see that in your questioning you're assuming that the present must have been influenced by time travellers if they are to ever exist. Well, for that to be correct, you'd have to assume that there ARE alternate realities for each point of the timeline. Like, right now there is an alternate reality for yesterdary, one for tomorrow, one for 10 years from now, and one for a zillion years from now. If that was the case, then your theory that "if time travelling was possible and would be done in some point, it has already happened", would be right. But there is no reason to assume that this *multiple realities for each point in the timeline* thing exists.

[/ QUOTE ]

To paraphrase Inigo Montoya, you keep using that phrase, multiple realities; I do not think it means what you think
it means. The idea is not that there is a separate reality for five minutes ago than from now, and yet another reality for five minutes from now. The idea is that there may be innumerable alternate nows.

[ QUOTE ]
Even more, you ask "where are the time travellers"

You say time travellers would be docking in the bahamas or w/e... You talk about lucrative business! That's just nonsense to assume all that /images/graemlins/smile.gif

[/ QUOTE ]

I didn't assume it. I merely meant I think it seems likely that if time travel were possible, we should probably observe time travellers. However, just because we don't does not prove it's impossible, as I've said.

[ctj]

[ QUOTE ]
One of the authors that I think treats time travel in a fascinating and believable way is Dr. John Kessel (http://www.amazon.com/gp/product/B000C4SNA8/qid=1136223041/sr=2-2/ref=pd_bbs_b_2_2/103-8484132-5162210?s=books&v=glance&n=283155). I took many writing classes under him in grad school, and I highly recommend him. His time travel short stories are also fantastic (e.g. The Miracle of Ivar Avenue).

[/ QUOTE ]

I would also highly recommend his time travel novel, "Corrupting Doctor Nice".

Regards,

C.T. Jackson

[soon2bepro]

borodog: when you say that if in the future time travel was to be invented we'd be seeing the tourists now, you're assuming that the future has already happened. Or rather that it's happening now.

But where does this assumption come from, really?

For all we know, time is only the number of events that happen in this universe. It's the universe "working". We simply simbolize that as a timeline just like we do when we talk about history or the future for that matter. But there is no way to tell wether this reality is connected to another one which is the same as this, only at another point in the timeline.

I think you should really look into this and you'll realize that you whole idea relies on the basis that simply because there will be a future, whatever changes that future can make on it's past (this present) will have already happened.

You need these alternate realities for this to become a must. Of course, without alternate realities, it could be a maybe. But it's definitely no reason to assume that time travel is impossible.

Btw, if you think mankind will continue to evolve endlessly, it soon becomes pretty obvious that it's not a safe bet to say that something will never be achieved

[ZeeJustin]

I have no clue what I'm talking about, but I'm going to say this anyway because it could lead to some interesting discussion, unless of course I'm just making a complete ass of myself:

According to the theory of relativity, all matter is constantly traveling through time.

[Matt R.]

[ QUOTE ]
According to the theory of relativity, all matter is constantly traveling through time.

[/ QUOTE ]

True. Another interesting tidbit -- if you're moving at the speed of light, you are not traveling through the time dimension. Impossible for anything that has a non-zero mass... i.e. matter. But photons do not travel through time, and a photon emitted at the big bang is the same age that it was at the beginning of the universe.

There is also a class of elementary particles called tachyons which actually gain speed when they lose energy. Their minimum speed is the speed of light, and they travel backwards in time.

Edit -- I just realized that it seems like it would be possible for matter to not pass through time as well if it was in a sufficiently large gravitational field. Especially if the whole going back in time via wormholes is possible. So, I guess it would be possible for matter to not pass through time. This seems right... but I'm far from sure as I have no idea how to do the math.

[Exsubmariner]

Even more mind bending than that is that the matter energy balance for the universe does not add up. Einstien called this concept the cosmological constant. He later second guessed the idea of a cosmological constant and called it his greatest mistake. However, as astrophysics learns more and more about the universe, they are finding that constant. The closest they have come to explaining it is something they call "dark energy." Dark energy seems to be a property of the void itself and is everywhere in the universe, even as the universe expands.

These guys know more about it than I do. (http://www.lbl.gov/Science-Articles/Archive/dark-energy.html)

[KenProspero]

Well, time travel is more than possible it's so easy a child can do it. In fact, every child does -- we all move forward through in time, at a rate of 1 day every 24 hours.

Further, relativity says that under the right circumstances, time can move at different rates for different observers (e.g., I could go on a space trip, where all my clocks would show that I was gone for 1 year, but when I returned, I might find that 10 years had passed on earth). Experiments have confirmed the relativistic effect.

So, the only real question is whether we can move backwards in time. I've seen it suggested that it may be possible, but all this is highly theoritical. No one really knows.

[mostsmooth]

[ QUOTE ]
Experiments have confirmed the relativistic effect.


[/ QUOTE ]
link?

[Borodog]

[ QUOTE ]
[ QUOTE ]
Experiments have confirmed the relativistic effect.


[/ QUOTE ]
link?

[/ QUOTE ]

Here you go. (http://www.google.com)

[mostsmooth]

[ QUOTE ]
[ QUOTE ]
[ QUOTE ]
Experiments have confirmed the relativistic effect.


[/ QUOTE ]
link?

[/ QUOTE ]

Here you go. (http://www.google.com)

[/ QUOTE ]
wow, how clever

[Borodog]

So clever it's made them billions.

And I could have given you this one (http://justfuckinggoogleit.com/).

[mostsmooth]

i wonder how much less they would have made if the people didnt keep pushing others to use it

[lastsamurai]

TO Answer your question in theory YES!

[mostsmooth]

[ QUOTE ]
[ QUOTE ]
Experiments have confirmed the relativistic effect.


[/ QUOTE ]
link?

[/ QUOTE ]
no link?

[Borodog]

Oh for Pete's sake, here (http://en.wikipedia.org/wiki/Time_dilation).

[Matt R.]

The first experimental evidence (http://www.bun.kyoto-u.ac.jp/~suchii/Edd.on1919.html) supporting gr.