Time Travel

[Matt1970]

Bill and Ted kinda put the kabosh on going back in time, atleast in our liftime. It's 12:04 right now. If I have access to a time machine in the future, I will go back to 12:05 on this same day and place a big red apple on my keyboard..............


Nope, no apple.

 

[Atheus]

Of course there might be no such thing as time, and what we call time is just our perception of change towards greater entropy. In that case a time machine would simply consist of a device which can reorder every subatomic particle in the universe to some saved state.

 

[Elias824]

Well I can travel through time, however i can only go forward. maybe ill got sit next to a black hold for a few min and then come back to earth in the year 3000

 

[BriGy86]

Originally posted by: destrekor

Originally posted by: Rubycon

Originally posted by: BriGy86
Keep in mind we are already able to see back in time in a sense. Just about all of the galaxies and far off objects in space are being seen as they were millions if not billions of years ago since that is how long it took the light to reach earth.

Right and if one left the planet fast enough they'd be able to pick up broadcasts from past events. example The conversion (due to red shift) as well as sensitivity would be the greatest challenge.

Being at the same place AND past time is the big challenge.

In this concept, one could watch history as it was happening, but could not be there to fully experience it, let alone live it or try and change it, eh? Jet off far off into space FTL, and carry a super crazy telescope that can be pointed at Earth once you are at your desired distance/red-shifted time line, one that can go close enough to see the events happening on the ground.
Of course, that pesky cloud cover would prove to be an issue.

Actually... hmm, is that even possible, at least through theory (let alone the requirements of FTL and crazy powerful telescope). Could one, if given these gifts, be able to see the past happening on the ground? Since the Earth bounces light off, but also absorbs light, what light would one be able to see out in space from far away?
Or is that the sensitivity issue you mentioned? The telescope, I'd imagine, would have to be able to pick up the very little light that bounces off of humans, or whatever, at that kind of distance, right?

The light from the sun would drowned everything out. currently I think they're only able to find planets based on wobbles of stars and other instruments. I don't believe a planet has actually been "seen" in a different solar system.

 

[silverpig]

Originally posted by: BriGy86

Originally posted by: destrekor

Originally posted by: Rubycon

Originally posted by: BriGy86
Keep in mind we are already able to see back in time in a sense. Just about all of the galaxies and far off objects in space are being seen as they were millions if not billions of years ago since that is how long it took the light to reach earth.

Right and if one left the planet fast enough they'd be able to pick up broadcasts from past events. example The conversion (due to red shift) as well as sensitivity would be the greatest challenge.

Being at the same place AND past time is the big challenge.

In this concept, one could watch history as it was happening, but could not be there to fully experience it, let alone live it or try and change it, eh? Jet off far off into space FTL, and carry a super crazy telescope that can be pointed at Earth once you are at your desired distance/red-shifted time line, one that can go close enough to see the events happening on the ground.
Of course, that pesky cloud cover would prove to be an issue.

Actually... hmm, is that even possible, at least through theory (let alone the requirements of FTL and crazy powerful telescope). Could one, if given these gifts, be able to see the past happening on the ground? Since the Earth bounces light off, but also absorbs light, what light would one be able to see out in space from far away?
Or is that the sensitivity issue you mentioned? The telescope, I'd imagine, would have to be able to pick up the very little light that bounces off of humans, or whatever, at that kind of distance, right?

The light from the sun would drowned everything out. currently I think they're only able to find planets based on wobbles of stars and other instruments. I don't believe a planet has actually been "seen" in a different solar system.

Actually planets have been resolved next to their parent stars.

 

[kotss]

Originally posted by: GuitarDaddy
Time travel and warp speed are nice to theorize about but both are nothing more than a twist of reason always to remain in the theoretical world.

Warp speed for example, what method of propulsion could possible propel you faster than the purest form of energy (light)? Not holding my breath for a proof of theory taceon drive

The idea behind warp speed is not go faster than the velocity of light itself but to go faster than the average velocity of light. You "somehow" bend space and then travel through the bend while light still has to travel around the bend (basically create a stable wormhole). You have effectively traveled a distance quicker than light without exceeding the speed limit and being pulled over by the universe cops.

 

[IHateMyJob2004]

Originally posted by: aldarius
Hi all,

Ive just finish watching this show explaining the possibilities of creating a time machine.

world's first time machine

But the problem i have is this. In this part 5, he says that time travel to the past can only travel when the time machine is first built (3:48). Meaning if the machine is created now 2009, than in 100 years time 2109, the time machine can travel to only up to 2009 and not later, 2008 and beyond...

Why is this so?

Because you can say anything you want about something that doesn't exist. Saying I elieve i ngod doesn't make it so (unless you talk about perception being reality)

 

[ShawnD1]

Originally posted by: aldarius
Ive just finish watching this show explaining the possibilities of creating a time machine.

They probably failed to mention that traveling back in time breaks the laws of thermodynamics. If I go back in time, that means the atoms of my body are no longer in the present time frame, and that's bad. The only way around this would be if the atoms in my body in the current time frame switch place with the exact same atoms in the past time frame. This creates a new problem. The two different time frames are not in the same position. Right now I'm sitting at my desk, but 20 minutes ago I was standing next to the coffee machine. If I warp back 20 minutes, will I be at my desk or will my atoms be next to the coffee machine? Since my past atoms were next to the coffee machine, I must warp back to the coffee machine. If I'm warped back to the coffee machine and my brain chemicals are put in the same position they were 20 minutes ago, I wouldn't even realize I warped back in time because I would be literally the exact same person I was 20 minutes ago.

I tend to think that if time travel happens (hey it could happen), it would only happen in a state of equilibrium where the exact same atoms move back and forth to different positions in time. The net result: absolutely nothing observable.

Let me give a parallel of what I'm talking about. If you fill a cup half full with sugar then fill the rest of it up with water, you'll have a saturated solution. Would you say that solid sugar molecules remain solid and dissolved sugar molecules remain dissolved? It certainly looks that way, but that is in fact wrong. A saturated solution is a state of equilibrium where solid sugar is dissolving at the exact same rate as sugar precipitates out. The net change at any given time is zero, but things are still happening. If time travel exists, this is how I think it would work. The fundamental particles that make up the universe would be in a state of equilibrium where the net "time travel" change is zero. Either that or time travel does not happen. Either or.

 

[mutz]

this is a very interesting matter, we just mentioned it the other day here,

With all due respect to egghead physics crowd, I persist that time is a human concept.

in a way it is so, thought time do exists as a chronological event.
you can't disregard the fact that things has happened in past time, as not everything is happening at once,
this is very much obscure, there is this story of some "Buddha" - when a man comes to him telling him he likes to get marryied, so this buddha tells him,
please go to the village and bring a glass of water (or something like that), so the man goes, finds a girl, marries her, bring children and all the deal, then after some 20 years, he's wife gets very ill, as being vey concerned he wanders through the woods seeking that old Buddha looking for some treatment for his partner, at the Buddha's abyss, suddenlly, he comes at a clearing and sees this Buddha sit under a tree, he's all peacefull and he can feel the intesity in the air, he approaches him slowly and sits silently down, the Buddha is very close and so the man can't hold himself and asks, whether he could find some cure for his wife, the Buddha looks at him silently and replies,
did you bring the glass of water dear sir ?
so in a certain prespective, time does not exists but on a different one, things do happen, you don't go down the street meeting Napolion.. :laugh:

p.s -

Well, how about looking at it this way. This is all speculatory and has no basis in reality, but as a thought experiment I find it interesting. If we assume that we CAN go back in time, perhaps any time travel that will result in that said time travel not taking place simply will simply cancel itself out. So if I go back and kill my grandfather, then I would never have gone back and killed my grandfather, hence I never will go back and kill my grandfather. So even though I in a sense have the capability to step into my time machine and kill my grandfather, I never will. I could possibly go back and kill my friend Tom's grandfather... but of course, if I never knew Tom, why would I have gone back to kill his grandfather? To look at it from a multiverse point of view, maybe it is not possible for a universe to "branch" when one of the branches will lead to a time travel event and an associated time paradox. Only the non-paradoxical branch would be allowed. Any act to, say, alter history would thus be problematic - if you went back and killed Hitler in 1920, then you would never have had reason to go back and kill Hitler in the first place, now would you? You could still go back and be a pure observer of events, or you could interfere in a non-goal-based way, at least in a minor sense - if I go back and take a dump on someone's porch in 1980, that would be unlikely to have repercussions wide enough to cause a paradox. If I kill a random guy in the street in 1990, that is unlikely to cause me to change my mind about killing a random guy in the street in 1990. Since the ramifications of a change in the timeline grow as time passes, it is conceivable that longer jumps would be less likely to be "successful" (a failure would, of course, never happen in the first place). Killing a random hunter in the stone ages is much more likely to cause widespread changes today than killing a random guy off the street in 1990. Perhaps successful (interfering) time travel is exceedingly rare, indeed so rare that it has never happened in our time in our reality, or has interfered in such a minor way as to go unnoticed.

this is quite smart :laugh:..
as been said, if one goes and kill hitler, hitler would not exist later on to be thinking "yeah, there is a reason to go kill this guy.", he simply wouldn't exist.
so there is only one change possible, afterwards, it's being erased from the face of history.
another thing is, u can never know, if u kill him, u wouldn't be rasing someone even crazier then him..
then u go back again and change,change and change etc. without being able even to record it.
at the end,
changing history is distorted, and cannot be predicted by anyone!
even if one goes back anywhere, he might ruin something as something will interact with him somehow as so change the all face of earth eventually,
like the butterfly effect.

 

[BladeVenom]

Originally posted by: Modelworks
I like the idea that time is unique to each person. You could go back and kill your parents before you were born and you would still exist. I would be like an observer outside of the current time line around me.

I read the same thing in a Sci-fi story. Which one was it? I don't remember.

 

[William Gaatjes]

Originally posted by: spikespiegal

The reason for time is to keep everything from happening at once.

:thumbsup:

With all due respect to egghead physics crowd, I persist that time is a human concept.

Well, there has been done research where they found that the brain actually stores memories by creating timestamps that are linked to these memories. Therefore we have indeed a tendency to look at everything with time in our mind. It gets indeed scary when you cannot recall if something just happened or still is happening or still must happen.
It is the easiest way of categorising information.

I think time is an effect. Time is that which prevents all energy to be used up at once in the universe. Without time there is no universe as we know it. I agree with Harvey tho.


I find time travel difficult. I feel the only way time travel is possible by use of alternate universes. Each universe having one event different then all the other alternative universes. And i wonder if that is even possbile.

In that case you can kill your grandfather and you would live on. And that is also the reason why you wont find timetravelers when it even is possible. Because at the moment they go back in time they change something and they will not be able to go back to their own universe. You will always end up going to alternative universes but never end up in the one you started with and want to go back too.

 

[mutz]

I feel the only way time travel is possible by use of alternate universes

another universe seems blurry,
one obligating point is, that traveling back in time, one cannot perceive where he would land,
as the planets are moving and going six month's at the same place would land u right in space :laugh:, in a wall, or even inside a mountain or under the ground.
another point to eaxmine, is whether anyone would like to travel to the future (and how is that possible?),
if u'd like to travel back, all u need to do, is probably pass the speed of light.
and would anyone would like to travel to a world he has almost no clue of how it would look like? where he understands nothing?
it seems that even 25 years from now, people from this time, will most likely be like prehistoric man living today..

They probably failed to mention that traveling back in time breaks the laws of thermodynamics. If I go back in time, that means the atoms of my body are no longer in the present time frame, and that's bad. The only way around this would be if the atoms in my body in the current time frame switch place with the exact same atoms in the past time frame. This creates a new problem. The two different time frames are not in the same position. Right now I'm sitting at my desk, but 20 minutes ago I was standing next to the coffee machine. If I warp back 20 minutes, will I be at my desk or will my atoms be next to the coffee machine? Since my past atoms were next to the coffee machine, I must warp back to the coffee machine.

i think u get this a bit wrong,
if one travel's back 20 minutes, he wouldn't be the same guy he was 20 minutes ago but rather live parallel to him,
there would be 2 instances or otherwise there isn't any meaning for the travel as you'll be the same guy and not even aware of that, u will live in a loop.
the concept behind traveling back in time, is not taking the whole structure of time back, but rather take you'r self back into recent happennings..

by destrekor Maybe one day we'll find a naturally existing link between different areas of time, or something that lends more to that debate. again, such as a wormhole.

that and the multi dimension concept u had, realy starts to sound more like it,
it seems that time travel might be possible.. by bending space, at space, as doing it on a planet might be too risky, but out side of it, a "time machine", might be able to change the dynamics of it, alowing for instance, traveling huge distances in moments.
it would be a momentary event demanding only a dimensional leap.

 

[Fox5]

Time is ALWAYS the independent variable for a reason.

 

[SilentSin]

if one travel's back 20 minutes, he wouldn't be the same guy he was 20 minutes ago but rather live parallel to him, there would be 2 instances or otherwise there isn't any meaning for the travel as you'll be the same guy and not even aware of that, u will live in a loop.

I think he was addressing conservation of mass. Matter cannot be created or destroyed, it merely changes states or is converted to energy.

If you went back 20 minutes in the past and your old-self from 20 minutes ago still also existed in the same universe, you would have effectively just added the amount of matter residing in your body to that system without first having converted it from energy. You just broke that law of conservation and now the universe mass:energy ratio is out of balance. Many current theories depend on that delicate proportion of mass and energy, to say that it is possible to simply add matter to the universe in this way would completely alter everything.


I tend to view the idea of time travel much like Nathelion. Most things in the universe seem to lean towards the path of least resistance. That is, if something's supposed to go a certain way it probably will (think occam's razor, electricity, fluid flow, etc). If you take that approach to time travel you will come to the conclusion that if it is possible then an outside observer wouldn't even notice that it has happened. How would you know if someone came back in time and killed Hitler before he could do anything? Your memories would also have been different because you would have been living in a reality without Hitler your entire life. The reality you are in now is that way because Hitler lived, because the Egyptians built the pyramids, because some cavemen harnessed fire, because the Earth formed at a specific distance from the Sun, because hydrogen fuses to form helium, etc.

The universe right now is in its current state because that state is the one that makes sense. It's the state that works the best given the previous state, and that previous state is based on the one before it. It's basically cause and effect. You should theoretically be able to place the universe in rewind (or fast forward) if you were to know the action and reaction of every single atomic collision and electromagnetic wave there ever was. Think about computer simulations, you can fast forward and rewind at will because the reactions are in a closed system with measurable results. If we are to believe that the universe is a closed system then it should also be possible on that scale as well. Obviously there is no way to even comprehend all of the interactions across the universe at a specific moment, let alone all of them that ever were and ever will be, but in theory that's how it would work.

One could say this is an extremely unromantic way to look at the universe. It basically says there is no such thing as free will, everything you have done and can do is the result of some previous reaction. That reaction could be the electrical impulses in your brain that cause a conscious thought that you perceive as free will, but in reality that happened due to chemical reactions and biological processes. However, I think of it as being super romantic in its own way. This means that literally EVERYTHING in the universe is connected in some way.

To take a line from 1984: "He who controls the present, controls the past. He who controls the past, controls the future." They are all dependent on one another.

PS- For some interesting reading regarding off the wall time travel theories, check out Rant: An Oral Biography of Buster Casey by Chuck Palahniuk. It's just as erm.."strange" isn't the right word but it's the first that comes to mind..as his other novels so you have to be in the right mindset. The cascading grandfather paradox blew my mind, though.

 

[mutz]

you would have effectively just added the amount of matter residing in your body to that system without first having converted it from energy. You just broke that law of conservation and now the universe mass:energy ratio is out of balance.

this is an interesting matter that threatens at puncturing the whole time travel concept balloon.
how can something like that could be avoided?
maybe at the cost of replacing a same charasteristic object which seems (to the lowest level) impossible.
maybe time travel is not an appropriate thing to do, as things should remain as they are, as not being mixed or harassed,
everything has it's place and those his "time", and so mixing different realities is a method for enticipated destruction.
as been proposed by destrekor a movement through space and so time (as space is time) should be happen probably at the dimensional tweaking level, as reaching evolving worlds, millions of light years away, by "squeezing" space and passing through it as a needle goes through cloth.

How would you know if someone came back in time and killed Hitler before he could do anything?

if something suddently apears, you might see a new face in your neighborhood, in your building, vilage etc. this things doesn't happen without being notices..
i think, if people in the past haven't had the chance to assault him, this is due to a good reason, maybe if the holocaust didn't happen, this would imply a greater mass of people around the world, implying crucial side effects to the politics, demographic aspects etc.(which is raising thought, and takes this disscusion in quite a different way..).

The reality you are in now is that way because Hitler lived, because the Egyptians built the pyramids, because some cavemen harnessed fire, because the Earth formed at a specific distance from the Sun, because hydrogen fuses to form helium,

exact,
u are the content of it, the all movement.

You should theoretically be able to place the universe in rewind (or fast forward) if you were to know the action and reaction of every single atomic collision and electromagnetic wave there ever was. Think about computer simulations, you can fast forward and rewind at will because the reactions are in a closed system with measurable results. If we are to believe that the universe is a closed system then it should also be possible on that scale as well. Obviously there is no way to even comprehend all of the interactions across the universe at a specific moment, let alone all of them that ever were and ever will be

true,
it isn't possible, otherwise u'd be able to build another instance of it and the corrent one is simply meaningless, denying the presence of existance, of love itself!

One could say this is an extremely unromantic way to look at the universe. It basically says there is no such thing as free will, everything you have done and can do is the result of some previous reaction.

at that perception, there is a cause and effect, a start&.. end.
if there would be an end to all life, what was the purpose of it? what was it's meaning..?!
it was absolutely meaningless and has no aim,
by saying that, one actually says that life can be measured and so it is a closed system".
so maybe we should consider putting aside the all cause&effect..! see..?

I think of it as being super romantic in its own way.

that is understood, but what is romantic at a lion eating a cove..?
and you'r a part of it, part of the whole movement, so, life isn't exactly romantic.. (i'm talking very patiently ofcourse),i wander if you see it sir..
maybe we'd like to give it this sense, but i think, a galactic explosion, isn't quite a romantic event for that matter, it is a fact, an obligating part of existance, a nessecity of it,
and thats the BEUTY of it.. the lack of fear, of impedence.., guilt.., the cruelty of it ,the VITALITY of it, - no look back - , no concession - seeking shelter..
no compromise,

it is very hard explaining this on hand, it becomes very lossy.

 

[SilentSin]

Originally posted by: mutz
if something suddently apears, you might see a new face in your neighborhood, in your building, vilage etc. this things doesn't happen without being notices..
i think, if people in the past haven't had the chance to assault him, this is due to a good reason, maybe if the holocaust didn't happen, this would imply a greater mass of people around the world, implying crucial side effects to the politics, demographic aspects etc.(which is raising thought, and takes this disscusion in quite a different way..).

It's a lot more simple than that really, you don't have to take into consideration morals or ethics and whatnot. I'll make a reference to sci-fi here, let's call this a Terminator paradox. Say a present location in space-time is described as Point A (ie- somewhere on Earth June 9, 2009). Another location in previous space-time is Point B (ie- April 1, 1920). Just prior to Point A a Time Traveler T makes a decision to go back in time to assassinate Target X at Point B before Target X does something terrible.

Now, suppose the assassination is successful. In the "new" reality after Point B, Target X is dead and never committed the crime, thanks to T. When the universe comes full circle and we are now at Point A once again, Target X is no longer considered a threat and never was. Time Traveler T (if he even exists at Point A with access to a time machine now, remember that changing the past changes everything) would therefore not have needed to make a decision to go back in time to assassinate Target X and the time travel would not have ever taken place to begin with.

In reference to the Terminator series, if the machines were successful in killing John Conner then they never would have existed to go back to kill him in the first place because JC wouldn't have existed to send his own father back in time and crush the terminator in the steel works so that humans could find it later, etc. The fact that the machines exist is proof that they failed to kill JC. Trying to think through these situations can really mess with your head. It gets exponentially more confusing when you try to make rules that allow for things like that to happen, like alternate universes and branching time paths.

Which comes back to my original mantra, KISS (keep it simple, stupid). What sounds more complicated? A universe that has one timeline that makes sense and does not allow for these time travel paradoxes to exist, or a multiverse with infinitely possible timelines where literally anything can happen based on vastly complex logic that is nearly impossible for us to comprehend.

One way around some of these problems is to develop a system that says you cannot travel back in time prior to when the time machine was turned on. You would still have to deal with all the same paradoxes for the time AFTER the time machine was created, but at least you've eliminated a large chunk of space-time from the equation. Even so, what if we find a highly advanced alien race that has had a time machine running for billions of years already? We could then use their time machine to go back to times that were previously inaccessible with our own time machines. The paradoxes would be renewed.

In a very obtuse manner, I was trying to say in my previous post that the fact that we don't know of any time travel right now is evidence that suggests it can't be done, at least not the way we're thinking of it. A Time Traveler would have to be so discrete as to not alert anyone in the world of their presence and not change anything that would later affect their own time travel (and how could they know if it would?). So yes, even with my ideology time travel IS possible and could have happened already, but it becomes highly constrained and slightly boring in practice (you can't change the big stuff so why bother?). However, even mere observation can change the outcome of events profusely which quantum theory elaborates on. Quite the theoretical pickle time travel is.

 

[mutz]

Now, suppose the assassination is successful. In the "new" reality after Point B, Target X is dead and never committed the crime, thanks to T. When the universe comes full circle and we are now at Point A once again, Target X is no longer considered a threat and never was. Time Traveler T (if he even exists at Point A with access to a time machine now, remember that changing the past changes everything) would therefore not have needed to make a decision to go back in time to assassinate Target X and the time travel would not have ever taken place to begin with.

i'd say -
everything is happening for a reason, nothing is "just" happening, i'll state, there is order in all that, that is a very deep statement..
in reference to what u'v said, if T is going back to A and (lets leave aside this all termination thing.. ) do something there, u'd never even be aware, that something like this has happened, and, this is also highly irresponsible, as none can percieve it's future impact.
as been sayed, IF someone is to go back in time and suddenly apears "somewhere", he would be noticed, or otherwise, it'll have to take out of the scheme, somebody else ,like, if u have 100 balls on a table (filling it),and u go adding another ball, than one of them will have to come off, so, i think, the universe, will never allow this to happen. as a side point, if T has managed to change anything, it wouldn't be noticed so there seems to be no reason to do that. u will never know, if u prevented 1 catastrophy, u havn't actually created a second one.
and thats the funniest thing about it, as life is simply laughing at u'r efforts..
u come and move an atom to the right, and it is coming from the left..:laugh:

In reference to the Terminator series, if the machines were successful in killing John Conner then they never would have existed to go back to kill him in the first place because JC wouldn't have existed to send his own father back in time and crush the terminator in the steel works so that humans could find it later, etc.

that is exact, it's probably good, the film makers are doing that and not science..:laugh:

Trying to think through these situations can really mess with your head. It gets exponentially more confusing when you try to make rules that allow for things like that to happen, like alternate universes and branching time paths.

don't mess youself with that friend, this seems to be,
a never ending thought...

based on vastly complex logic that is nearly impossible for us to comprehend.

it doesn't seem to be possible to comprehend atall, i'm sure, if life was being made by some "large supercomputer", it might have been possible for it to calculate an instance of it, but once u indulge neverending variations of it, this is becoming pointless&meaningless,
some crazy scientists idea which have no good logic for understanding how things do happen, or going too wild with speculations..
life, make sense, otherwise, it wouldn't be possible for anyone to understand it.

what if we find a highly advanced alien race that has had a time machine running for billions of years already?

i'd say, for making some order in this matter,
the universe is large, extremely large, if u take a look at the galaxy in which earth is in, there are billions of stars and star systems in it,
other than that, there are billions of billions of galaxy that the best equiped telescopes migh see, and if u go to the farest galaxy and place one of these machines there, u'll probably be able to see far galaxies further on and on.
to come out with theories about the universe moving for 5 billion years, with the amount of knowledge humans have achieved is insanity.
to say, that everything has started by somesort of a big bang, is terribly unwise.
to say, that on all these other stars sorrounding, there hasn't been evolved any other forms of life,
is like having on the head,
a bucket.
if u accept these sayings, i'll add, that it would be possible to travel above the speed of light, (that would be a nessecity), and so,
visit other evolving worlds, on different galaxies.
i think the history of human, is to be left aside, if it came out this way, (as u said about the razor), than this is the best way that it could've come.
to summarize this matter, i'd say, that this video and what that professor (or doctor) is trying to do, is yet to be understood,
it's meaning, is hard to percieve yet.
i'd say, leave the past, to the past, what realy matters and has a true impact,
is what we do
in the present..

 

[AerieC]

Originally posted by: Atheus
Of course there might be no such thing as time, and what we call time is just our perception of change towards greater entropy. In that case a time machine would simply consist of a device which can reorder every subatomic particle in the universe to some saved state.

QFT

Time is a human concept based on rate of change (see the theory of relativity). Our whole definition of time is based on the rate of change of different things. It started with the rate of the earth's rotation, and we simply moved on to things like atomic resonance frequency (atomic clocks). All of these standards are variable based on factors such as temperature.

Time is not some magical dimension where all information about the location and energy of every individual particle in the universe is stored for future reference. Any individual "frame" in time is just the unique position and energy of each and every particle in the given area.

To literally "go back in time", all one has to do is create an exact duplicate of any given "frame" of time. This is why it has been said that if a time machine were created, it would only be able to go back to the point where it was created (i.e., the point where the machine started collecting data about each and every particle in the universe, or within a given area). Theoretically it would be possible to extrapolate the history of particles based on their current positions, velocities, etc., if it weren't for that nasty principle of uncertainty (Heisenberg), not to mention the absurdly enormous number of calculations that would need to be performed to revert even a very small area to an earlier time state. Devise a way to discover (and manipulate) the position and energy of every individual particle in a system, and you'll have discovered "time travel".

Unfortunately for the sci-fi enthusiasts, time travel as it appears in many an episode of Star Trek isn't at all possible. Sorry to burst your bubbles, but yeah, time isn't a navigable dimension that we can just wander around in, that's just the way our brains record and access events chronologically. The universe doesn't care about our "time"--it just keeps changing away.

EDIT-
BTW, yay first post! haha

 

[smackababy]

This is my primative theory on why, if time travel is possible, we don't see anyone from the future. As I understand it light is timeless. Traveling at the speed of light, time will go by for others but will seem like an instant for you, thus allowing you to travel forward in time. Now, the problem is traveling faster than light is supposed to allow you to travel backwards through time. It would seem unlikely that you could go to a time before you started traveling that speed.

 

[KIAman]

The thing is, in a non multi-dimensional view of time travel, you would have to believe in Determinism or Fatalism.

But if you believe in Determinism, traveling to the past is impossible considering events are pre-determined.

 

[AerieC]

/Facepalm at the lack of physics knowledge in this thread.

Originally posted by: smackababy
...Now, the problem is traveling faster than light is supposed to allow you to travel backwards through time.

Lol what? Special theory of relativity fail.

Seriously. Everyone needs to STOP thinking of time as something magical and separate from matter and space.

Time = matter changing in space. THAT'S IT! To go back in time is to go back in matter (i.e. revert matter to a previous state). There is no absolute, ultimate clock somewhere that's keeping time in the universe, nor is there some omnipotent hard drive somewhere out there keeping a record of everything that happens at every nanosecond. IT'S ALL JUST CHANGING MATTER.

Time travel the way most people think about it is impossible because most people sorely misunderstand time.