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We cant go back in time>>>>


pretender
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just because you can't imagine it being there doesn't mean it isn't. Humans can't conceptualize quantum mechanics, yet we know it exists.

 

indeed (hence the 'i dont know as much'), but it seems a simpler explanation to accept that time is a human invention to facilitate thinking about continual changes in the state of the universe, as opposed to something that actually exists. 'Matter changing' is simpler than 'time exists as a continumn, which is curved, allowing for every possible 'moment' to exist in some manner etc'.

 

Unless there's any actual evidence to suggest simultaniouse* existance of two or more 'moments', (eg, effect before cause, time-travel (other than forwards at 1s/s), or other temporal anomolies), i'm gonna stick with my 'time is a metophore for a dynamic universe' philosophy 'cos of okkrams razor.

 

-------

 

*not neccesarily simultaniouse by time, but if time exists as a continumn, then surely every possible moment must exist at once along the continumn?

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Isn't being cryogenically frozen just the same as travelling forward in time?

 

By defintion we are traveling through time right now, OK its nothing spectacular but its the truth...

 

I really can't see how time travel would work... for one I see the fact that going backwards in time would create a contradiction, the atoms in your body are clearly the same as atoms that already exist there so how can you be in 2 places at the same time? Would you simply vanish or be re-intergrated into that time?

 

Don't ask me... time travel is quite confuisng :(

 

Cheers,

 

Ryan Jones

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I think that is correct. I find it extremely annoying when time travel is just thrown into films and whatnot without thinking about the literal aspects of it.

For example' date=' the Terminator films. Nevertheless entertaining, they are just... well... wrong. It will take too long to go into the synoposis of the films

(see: http://en.wikipedia.org/wiki/The_Terminator)

Anyway, the point of it is that machines are sent back through time to kill (and protect) someone who later on in the future, becomes important. When they arrive from the future, they claim it is history to them (the future is their past).

 

Now, if that was true, there would have had to be one main/true timeline. The character would have had to survive by himself to get to the future and THEN send the machines back in time. In other words, he is sending machines back in time to protect himself when he has already completed the timeline with no interruptions yet apparently he wouldnt have survived without the machines. (I hope you are understanding this)

 

So, if there were machines there to kill and protect him which came from the future, he would have had to already completed the timeline and so render the necessity of sending the machines back pointless.

 

Its the same in the 3rd Harry Potter film/book when he saves himself with the patronus. He needed to have survived the whole timeline so he can reach the point to then go back in time and save himself. If the timeline is complete, going back in it is pointless and so the plot is corrupt (couldnt think of a different word)

 

So in reply to your comment, no we cannot (or shouldnt be able) to go back in time because as the French call it, it is the Perfect tense. It cannot be changed. If you want to go back in time and save yourself, you would have already had to survived the whole timeline without the aid of yourself and so going back is pointless.

 

Phew. Just my thoughts on the subject.

 

By the way, I am not putting down Harry Potter and the Prisoner of Azkaban or the Terminator films. They are both highly entertaining; just a little illogical in my eyes.

 

What then if you wanted to save someone else who did not survive his "time line"?

 

Not that I think that we can go back in time...

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Yer, I understand that we are always travelling through time (or with time.) When people get the idea of jumping from one point in time to another then this is a bit different. Travelling forward 'quickly' could be achieved by cryogenic freezing. You would experience no passage of time and then you are 1000 years in the future. It's still science fiction but it's nearly possible and the closest we'll get to stepping out of time, in my opinion.

 

As for travelling backwards, I agree with Dak. as information is lost with time (entropy increases) the is no way we could recreate the past by inference from the present. this requires that we assume that there is a copy of each point of the universe in storage somewhere. That the state of the universe at each time point is preserved. I don't know of any evidence that would suggest this is the case.

 

While trying to think about time travel I came up with this little paradox that is making my brain hurt. Its basically the same as all other time paradoxes but nice and simple.

 

You are sat in the lab having just powered up the first time machine ever built. There are two small portals, one where things go in and one where things come out, sat next to each other on the bench. All it does it send stuff back in time 3 seconds. The first object you try is a ball bearing. SO what happens? You see the ball bearing come out of the time machine 3 seconds before you put it in? What if you decide not to put it in after that? You obviously can't put the ball bearing in before one has came out or the machine doesnt work. What if you put the one that came out back in again? It seems that once something comes out of the 'out' portal you have to put that object in the 'in' portal 3 seconds later to prevent a paradox. Surely this kind of stuff just aint possible.

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If all the particles that make up a time traveler can be decribed as a wave function, this wave function can be made to interfere either destructivly or constructivly (or even the entire universe). If this wave function could be made to interfere with its self (going back in time), then the paradox would cause the wave function to interfere destructivly, stoping the timetravel. If ther is no paradox then this owuld be constructive interfereance and time travel might be able to occure (that is depending on other factors, like a working time machine, etc).

 

This allows backwards in time travel, but only if it does not cause a paradox.

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If all the particles that make up a time traveler can be decribed as a wave function' date=' this wave function can be made to interfere either destructivly or constructivly (or even the entire universe). If this wave function could be made to interfere with its self (going back in time), then the paradox would cause the wave function to interfere destructivly, stoping the timetravel. If ther is no paradox then this owuld be constructive interfereance and time travel might be able to occure (that is depending on other factors, like a working time machine, etc).

 

This allows backwards in time travel, but only if it does not cause a paradox.[/quote']

 

Im not sure I understand what you are saying really so I'm not sure if I believe it either. How does this relate to my example paradox for instance? Where effect comes before cause. What do you mean by 'interfere with itself going back in time' ?

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I think he means that they will cancel eachother out elimating the paradoxical element to your example. I have always thought of time as an illusion, a measurement of change fabricated by human minds. Progression, decay, time, its all made of two things: Change and perception. Time changes with different perceptions. That includes the cryogenically freezing yourself thus 'traveling forward in time', when in reality, we do such each second. Are we not traveling forward in time everyday? In a sense, I suppose a form of forward time travel is possible. Although I cannot see how we could ever be able to travel in the past: for it does not exist.

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I think he means that they will cancel eachother out elimating the paradoxical element to your example. I have always thought of time as an illusion, a measurement of change fabricated by human minds. Progression, decay, time, its all made of two things: Change and perception. Time changes with different perceptions. That includes the cryogenically freezing yourself thus 'traveling forward in time', when in reality, we do such each second. Are we not traveling forward in time everyday? In a sense, I suppose a form of forward time travel is possible. Although I cannot see how we could ever be able to travel in the past: for it does not exist.

 

Indeed, I agree completely. I think the point I was trying to make with my example was that paradoxes resulting from the existance of time travel are not just limited to rare cases where you kill your gran or something else equally specific, the idea is fundamentally parodoxical (if that makes sense). I get the impression that a lot of people believe time travel, into the past, is possible as long as you are really really careful. Which is the version of time travel often found in the movies.

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I don't specificaly belive that Time travel is posable, but neither do I believe that it is imposable. It is simple that there is no evidence one way or the other and that there are theories (and variations of theories) that confirm both conclusions. For me the jury is out (untill it can be shown to be one way or the other).

 

Im not sure I understand what you are saying really so I'm not sure if I believe it either.

If you think of the universe as a single quantum object (sum all the quantum states of all the matter in the universe) then it can be described by a single (all be it complex) wave function. This wave function would be subject to interference as any wave function would. The universe would be able to interfere with potential "copies" of its self in certain circumstances (time travel). Any destrcutive interference between these "copies" would prevent them from existing.

 

An annalogy would be a laser with a beam splitter.

 

If you tale the beam splitter and allow it to split the laser beam into two paths. At the end of one path you place a mirror that reflect the beam back on its self and a photon detector at the end of the other path.

 

If you adjust the position of the mirror so that it will send the beam back, but so that it will cancle out any photons that would take the mirror path, then no photons will be able to take that path. If it doesn't cancel it out then photons can take that path.

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"Well if the traveling to the past is possible why nobody hasn't come yet from the future?"

 

Maybe our world ended before we could build a functioning time machine.

 

So, there must be either alternate timelines or parallel universes for "time travel" to be possible.

Think of the grandpa paradoxon. If i travel back in time to kill my granpa, so, there i am, standing in front of him, holding a gun. I shoot and he's dead.

 

Version 1:

My past stays, but the future is changed. So, if i wanted to go back to my time (the OLD future) i'd have to travel BACK in time!

 

Version 2:

My past is eliminated and i'm stuck.

 

BUT time is either a constant, then you can't break out of your timeline.

Or it's not a constant, then you wouldn't be able to travel to a specific "place on the timeline".

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In some thoretical concepts of time machines, the limit on going back in time is limited to the existance of the machine its self. So you can't go back to before the machine was made. Scince we have yet to invent one, no one can come back to now.

 

Disclamer: This is all theoretical... :D

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I agree with reor, and have actually developed, a not complete thesis on parallel timelines each with alternating time flows. My father gave me the idea and we talked about it for awhile. It makes some sense and explains as to how time travel might be possible, but we have no idea how it would be done. One would have to break out of his or her timeline. Then again, based on perception we each have our own time line which makes up a gigantic one which is life.

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Hi after reading all the comments in the thread I get the general feeling is that time travel of any type is neither possible or even plausible however after a long debate with friends I do believe that it is very possible to go through time both directions however it would not be possible to visit the same place twice in two different times to break it down we can all agree that time itself travels at stable speed away from what would be the centre of the universe or away from the point In space where the big bang took place as we know if we travel at the speed of light time would stop but taking all into account that must be in a direction opposite to the centre of the universe so there for you are travelling forward but in order to get back to earth you would need to travel backwards again faster than the expansion of the universe so by the time you get back to the place you started the gain in time would be lost and you would have appeared to have not travelled through time at all and vice versa if you travelled at the speed of light towards the centre of the universe you would effectively be going back in time but in order to get back to a the place where you started you would need to travel faster than the give place thus losing any time gain although this is quiet a basic explanation you can get the idea but also take into account to go back in time you need to travel at all just stop where you are in relation to the universe and time would pass you by but again the rest of the universe would fly past you and to get back to the point to which you started you would need to be travailing faster than that object thus again losing any gain any feed back would be nice

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That would be the "other problem". Since we exist in a 4d+ universe, we'd have to find a way to teleport to the desired place and time.

I believe that it would require a constant supply of energy to stay in a certain timeline, otherwise you'd get "lost".

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we can all agree that time itself travels at stable speed away from what would be the centre of the universe or away from the point In space where the big bang took place

 

Not nessisarily, time is a part of spacetime so in one sence it is traveling away from the big bang then again it is possible for time to "slow in reverse" although extremely unlikley due to entropy.

 

as we know if we travel at the speed of light time would stop but taking all into account that must be in a direction opposite to the centre of the universe

 

First we need to define where the center of the universe would be... secondly we can't ever at light speed anyway...

 

so there for you are travelling forward but in order to get back to earth you would need to travel backwards again faster than the expansion of the universe so by the time you get back to the place you started the gain in time would be lost and you would have appeared to have not travelled through time at all and vice versa if you travelled at the speed of light towards the centre of the universe you would effectively be going back in time but in order to get back to a the place where you started you would need to travel faster than the give place thus losing any time gain

 

Your still trying to break a law of physics, you can't travel at or faster then light. Your prediction is that time is "expanding outward", how can you show this? If it were expanding outward then it would all be moving away from a fixed center, the center of the universe where the big bang would have occured and that would mean the point would effectivly be an anti-singlarity, a point where spacetime is being "created". Don't forget space time is not being created but rather stretched.

 

Sorry but I had a really hard time reading that paragraph because of the lack of punctuation, I don't see how it could be correct buy maybe one of the more knowledgable members can shed more insight :)

 

Cheers,

 

Ryan Jones

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A theoretical time machine is that of a Wormhole (even these are theoretical).

 

If you make a wormhole with the two ends (call them A and B) near each other and then take end B and accelerate it so it is moving at close to light speed and then move it away from you (say to Alpha Centauri) and back, you will end up with the end B at an earlier time (accoring to the "Twins" paradox of relativity) than A.

 

This means that if you enter B you will come out at an earlier time A end, with the reverse being true too, if you enter A you will end up at a later B end.

 

We now have our time machine. This is important as any discussion on what might be the posable results of time travel are closely linked with the actual "machine". For instance, this machine can not send someone back to before theis machine was made.

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  • 2 years later...

not to kick up a dead thread but its just not possible....in the ed time is relative to ourselves so if say...my best friend traveled back 2 years ago what would that do to me and you?? do we just become forcedto go back?? and say if i had a time mchine and traveled back to yesterday would the present me still exist?? there would be two of me in the same timeline?? whos controlling the other me if only 1 me exists?? if the world revolved around me then yea i think it could be possible but it doesnt...but existence (planets,bacteria,sun, galaxies) is too large to just bring everything back in age...only God Himself could...and if He did we would never notice....by the way sorry again i rarely ever post here but i love to check in a few times a year and read the debates and info

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I dont know as such... it just seems to me that the universe exists in an ever-changing state, and that once the universe has changed -- once something is 'in the past' -- it no longer exists, as there are no records being kept. In fact, I can't see how or where the information for past 'configurations' of our universe could be stored, so I dont see how the past could still exist in any way.

 

Interesting. I've never thought of the fact that the universe probably isn't storing the past.

 

On a side note: To people who say that time doesn't really "exist", I'm pretty sure it does. Matter is known for bending space and time...If time is affected by matter, then doesn't that mean that it must exist?

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