Why altering time should be impossible. (in theroy)

[Narrax]

I'm not a physicist, but I think "time" is just something we've created as humans to provide order to a non-ordered universe. I think the only way to travel backwards in time (because we can travel forward if we are able to travel at the speed of light, seeing as we are either moving through space or time, i.e. space-time continuum), is if we were to reverse the flow of entropy (that thing which says matter is getting more and more chaotic), while maintaining our own entropy going at a normal rate in the "forward" direction (into the future).

[Lord Kim]

For some reason all kinds of posts are going through from me, I refer you to my post further down.

[Puremallace]

Why have we never seen anyone from the future? Because you cannot go back in time.

uhh what exactly do you think UFO's are?

[Narrax]

No, reversing entropy will not change the flow of time. Entropy just happens to increase with time, time does not increase with entropy. There is only correlation not causation.

Thanks for the clarification. I should say I don't believe you can time travel and that there is only one flow of time, unless alternate universes exist, but I don't think they would exist in the way we think as in being a duplication of our world with just choosing door A instead of B for every possible decision, which leads to an infinite amount of possibilities. We could only suspend our progression of time by moving at the speed of light.

[Vinni]

Compensating for time dilation is used every day with GPS satellites.

But what is time dilation? Without explaining it, I'm seeing it as dilating of a human concept. Please explain, but no damn wikipedia links

[Lord Kim]

Sorry! New to mmo-Champs forum system. Double posted!f

[Lord Kim]

Thanks for the clarification. I should say I don't believe you can time travel and that there is only one flow of time, unless alternate universes exist, but I don't think they would exist in the way we think as in being a duplication of our world with just choosing door A instead of B for every possible decision, which leads to an infinite amount of possibilities. We could only suspend our progression of time by moving at the speed of light.

Whatever happend to my post? Good thing I ctrl+V it, before saving my edit.

repost + new:

I'm not a physicist, but I think "time" is just something we've created as humans to provide order to a non-ordered universe. I think the only way to travel backwards in time (because we can travel forward if we are able to travel at the speed of light, seeing as we are either moving through space or time, i.e. space-time continuum), is if we were to reverse the flow of entropy (that thing which says matter is getting more and more chaotic), while maintaining our own entropy going at a normal rate in the "forward" direction (into the future).

No, decreasing entropy will not change the flow of time. Entropy just happens to increase with time, time does not increase with entropy. There is only correlation not causation.

People have also said that one can move bakwards in time by traveling faster then light (tought experiment!). But when speeds faster then light is plugged into the equations of special relativity you get imaginary time, not negative time.

However! If you know the logic behind relativity, you'll come to the conclusion that moving faster then light means going backwards in time. (You see a forward-moving lightbeam moving backwards).
To me, this implies that either the theory of relativity(time) or our understanding of it, when it comes to speeds greater then light is, wrong and has to be improved.
Not wrong as in: "Theory is crap and good for nothing".
But wrong as in: "Theory holds for everything we know except in this physically impossible state, where logic goes against theoretical predictions".

What this improvement would be, I don't know. But I know Stephen Hawking is very keen on imaginary time to explain singularitys.

[Sigma]

This thread is going to be incomprehensible inside 3 pages, guarantee it.

incomprehensible after the first half dozen post's

If you could go back in time and kill your grandfather, something would have to stop you from killing him.
because if you killed him before your parents birth, you would never exist to go back and kill him (we already established this as the grandfather paradox)
If this is the case then there is no such thing as "Free Will" as everything is per-ordained. If everything is per-ordained then that proves that there is a higher power and the universe was created for a purpose and this would mean that some god like being created everything. Now since all religions are based on a belief system with out the actual ability to prove anything, Then surely it stands to reason that by proving that the universe was created with an intended purpose that if you where to go back in time to attempt and ultimately fail at killing your Grandfather to some unknown effect or reason that all religion is false.

[Yohassakura]

But what is time dilation? Without explaining it, I'm seeing it as dilating of a human concept. Please explain, but no damn wikipedia links

As the Moon is 400,000km from the Earth and the speed of light is 300,000km/s the time taken for light to travel is about 1.3 seconds. If you were looking at a clock right next to you, and one on the moon, the one on the moon would be 1.3 seconds slower. (There's a bunch of other things that can change the time of a clock as well, such as gravity).

Imagine that if you looked at the moon with a telescope, then traveled several times faster than the speed of light to the moon, you would have seen yourself at the moon before you arrived there.

Or, if you were several light years away from a planet, and traveled towards it faster than the speed of light, you'd see that planet "rewind" because you're travelling faster than light.

[beefchorizo]

Altering time, history or even small events has been a dream many people have had.
This thread will focus on altering the passed and not the future.

One reason to why altering time, history or even small events should be impossible.

Lets say that I have acquired means of traveling in time, allowing me to change the passed.
Lets now take a senario where i lost a loved one.
So i go back in time and prevent this person for dieing.

This will create a paradox where I never lost this person and have no need to go back in time to save them, thus i dont, and they will stay dead.
This works the same for any other given senario you find your self going back in to alter time, removing the reason for you to go back and change it in the first place.

Another senario that I have thought alot of. I have the means to create a worm hole that will go back in time, i now create one and shoot my self, 1 min back in time. Who killed me? I was killed 1 min before I could pull the trigger, and there for I cannot have killed my self.

ofc If u were to go back and lets say, kill Hitler after the war was over then, at least i belive, that should not alter time in any major way that would make it impossible for you to have the idea to kill him your self


What are your thoughts of these paradoxes that should make it impossible, in theory, to alter history in and major way.


Disclaimer: I'm not a scientist/physicist nor do i have a substantial understanding of how time travel would have any impact at all.( but lets face it, do anyone?)

bolded is the main reason i dont believe in changing the past. and no, i don't believe in alternate time lines. it makes you less you knowing that there are other "versions" of you out there.

[pagl]

I've always tought about time traveling and stuff, read all the probably causes and paradoxes for it not to work and i think i came up with something plausible.
Scenario: The time machine is built and it's fully functional, yes, but now, no one in the project or that even know about the time machine will ever be able to ride it to the past, because the mere tought of changing something would lock you in the Grandfather paradox.
Passenger: Someone smart, fit, that has been tested to be optimal and it's in trainning for something, a project, he knows he may be called someday for something big that when it happens he's to leave his family and friends forever, someone brilliant enough to not know anything yet when he gets "there" and realise where/when he is, to act, to estabilish himself and think, ok, they sent me to the past, i know some shit that could be changed and since i was sent to the specific time, i must do. ie. Hittler timing, ww1 events, 9/11 and some other catastrophic event.

Now, bear with me, the guy must not know anything about his "calling", where to, how to get there and what he's supposed to do.

Anyone get my drift? Any suggestions to improve our little paradox fixing?

Sorry for bad english. =D

[Reeve]

As the Moon is 400,000km from the Earth and the speed of light is 300,000km/s the time taken for light to travel is about 1.3 seconds. If you were looking at a clock right next to you, and one on the moon, the one on the moon would be 1.3 seconds slower. (There's a bunch of other things that can change the time of a clock as well, such as gravity).

Imagine that if you looked at the moon with a telescope, then traveled several times faster than the speed of light to the moon, you would have seen yourself at the moon before you arrived there.

Or, if you were several light years away from a planet, and traveled towards it faster than the speed of light, you'd see that planet "rewind" because you're travelling faster than light.

That's not really what they're talking about with time dilation. They're talking about time ACTUALLY moving slower, rather than the difference in time between when something occurs and the light reaches you.

So if you have a radioactive isotope with a half-life of 10 minutes, and you have it approach the speed of light, the half life of that isotope could last centuries from the perspective of someone on Earth, even if the Isotope hasn't moved very far (let's say it's in orbit around something very massive nearby). It's time ACTUALLY slowing down for that object relative to slower moving objects.

[furydeath]

There is also the one theorie that events must happen or else something greater could happen. Like if you went back in time and stopped a bus crash that killed 10 people you might have saved them 10 people but doing so causes 10 other people or at most a lot more then 10 to be effected.

[Ghâzh]

But what is time dilation? Without explaining it, I'm seeing it as dilating of a human concept. Please explain, but no damn wikipedia links

I'm not going to do your research for you and dig up any sources but I can try to explain. The whole theory of relative velocity time dilation is based on the fact that the speed of light is a constant and you can not exceed it. When an object is moving at speed X and it's emitting light that obviously moves at speed of light we get a problem. When you count in the speed of the object and the speed of light we get a speed that's supposedly faster than speed of light, which is not possible (theories of relativity). That means that for the described situation to be possible the actual frame of time in which the event happens has to "move slower", hence, time moves slower the faster you move.

There's also evidence supporting this if you don't believe the theory. An atomic clock inside a satellite of a space station counts time slower than same kind of clock at the surface of earth which is explained by the faster speed of the unit in space. Gravitation also has an effect.

[Yohassakura]

That's not really what they're talking about with time dilation. They're talking about time ACTUALLY moving slower, rather than the difference in time between when something occurs and the light reaches you.

So if you have a radioactive isotope with a half-life of 10 minutes, and you have it approach the speed of light, the half life of that isotope could last centuries from the perspective of someone on Earth, even if the Isotope hasn't moved very far (let's say it's in orbit around something very massive nearby). It's time ACTUALLY slowing down for that object relative to slower moving objects.

True, they were talking about relative TD rather than Velocity based TD... But that's the only way that I can explain it :P

Time moving slower itself is generally due to gravity (from what I know). Black holes in theory can slow down time.

[Kurioxan]

I'm not going to do your research for you and dig up any sources but I can try to explain. The whole theory of relative velocity time dilation is based on the fact that the speed of light is a constant and you can not exceed it. When an object is moving at speed X and it's emitting light that obviously moves at speed of light we get a problem. When you count in the speed of the object and the speed of light we get a speed that's supposedly faster than speed of light, which is not possible (theories of relativity). That means that for the described situation to be possible the actual frame of time in which the event happens has to "move slower", hence, time moves slower the faster you move.

There's also evidence supporting this if you don't believe the theory. An atomic clock inside a satellite of a space station counts time slower than same kind of clock at the surface of earth which is explained by the faster speed of the unit in space. Gravitation also has an effect.

Yep, that is correct *shrugs*
However if you view time as a dimension or a simple human construct to make sense of entropy/energy transfers and their rates, the conclusion will vary, one allows for time travel (if its a dimension you can supposedly move either way) if it is an illusion of the mind there is nothing you can do aside from slowing down or speeding up natural processes which is quite different from the idea of time travel.

The clocks differences and time dilations all can be explained by difference in rates of decay/energy transfer, and if that is the case then again, calling something going really fast time travel then you have to call your fridge a time travel machine, same principle (slowing down processes) different means (removing energy vs gravitational effects on matter)

[Agrias-Oaks]

I'm not going to do your research for you and dig up any sources but I can try to explain. The whole theory of relative velocity time dilation is based on the fact that the speed of light is a constant and you can not exceed it. When an object is moving at speed X and it's emitting light that obviously moves at speed of light we get a problem. When you count in the speed of the object and the speed of light we get a speed that's supposedly faster than speed of light, which is not possible (theories of relativity). That means that for the described situation to be possible the actual frame of time in which the event happens has to "move slower", hence, time moves slower the faster you move.

There's also evidence supporting this if you don't believe the theory. An atomic clock inside a satellite of a space station counts time slower than same kind of clock at the surface of earth which is explained by the faster speed of the unit in space. Gravitation also has an effect.

This is correct, steven hawkings also touched on the subject and used an example using a train traveling at the speed of light, so anyone riding the train will also be traveling at that speed, now if you were to move forward inside the train while already at the speed of light, the universe cannot accept that (apparently you cannot go faster than light) so you will get slowed down. http://www.dailymail.co.uk/home/mosl...#axzz2JiUYMtTG

[Henako]

Time travel is a bad subject because nobody knows dick about it, so at best you can theorize.

[staart]

You can not go forward or back in time because it does not exist. It's simply a manmade construct.

You as a human are constrained by the universe you are in and the observable laws it contains.

You yourself could not go back to a different point in the lifespan of the universe but perhaps if there was someway to move the universe itself or step outside it then maybe you're getting somewhere but still a long way from what you want.

Everything is a manmade construct, since we are humans, and we choose to call it reality. It makes no sense saying it's 'just a manmade construct'.

You can definitely go forward in time just like you go forward when you start walking, you can be timeless even, if you were a photon.

[semaphore]

You can not go forward or back in time because it does not exist. It's simply a manmade construct.

Of course time exists. Do you think there was no passage of time until humans evolved? Because the universe is 13.7 billion years old.

---------- Post added 2013-02-02 at 08:43 AM ----------

Without explaining it, I'm seeing it as dilating of a human concept.

This statement is prima facie absurd.

---------- Post added 2013-02-02 at 08:44 AM ----------

I'm not a physicist, but I think "time" is just something we've created as humans to provide order to a non-ordered universe.

Clearly the billions of years prior to human existence is completely imaginary.

---------- Post added 2013-02-02 at 09:00 AM ----------

it's just that as far as I know anything similar to do with time is only a theory

There's no such thing as "only a theory" in science.