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Is Time Travel Possible?

DrNano
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Posted 04/02/08 - 12:50 AM: Subject: Is Time Travel Possible?	#1
I have thought about this one for a while and after failing to find any compelling information regarding whether traveling through time is possible (ignoring those admittedly pretty pictures of whirlpool-like distortions in space-time that are meaningless) I came to the following 3 tentative conjectures regarding the impossibility of time travel (TT) : 1.) Firstly, the obvious argument against TT is the grandfather paradox : you cant go back and kill your grandfather, which would eliminate the possibility of your existance in the future preventing any 'you' from going back in time and commiting the murder in the first place. The only way around this one is to posit that there are many (necessarily infinitely many) alternate timelines/universes that TT creates / travels to and that you created a new one when you travelled back and changed the past. 2.) The multiple universe hypothesis: so either your arrival in the past instantaneously creates a new/alternate universe (which breaks so many physical laws it would even make a chronic bell's palsy sufferer cringe) or TT is actually the process of travelling to an alternate universe where everything is in an equivalent physical state except at a different stage in its time line). But then your arrival would change everything in that universe, and vice versa your physical departure would change everything in your previous universe (ie all gravitational, magnetic fields etc would change) and so much for conservation of mass-energy for each universe as a whole. Additionally I think that Occums razor, although not a scientific principle in itself, encourages us to choose a single universe (or many universes that are independent and cannot exchange matter/energy) over infinitely many universes that are constantly swapping matter/energy and are in a constant state of flux where no conservation laws apply etc. 3.) For those of us that have an understanding of the intricacies of special relativity will know that two events that appear simultaneous to one observer (reference frame) will not appear to be simultaneous to another reference frame ("relativity of simultaneity"), implying, amount other things, that from one reference frames perspective two events (A and B) that are measured to occur simultaneously will have event A occuring before event B in some other reference frames and event B occuring before event A in others. Ie that some reference frames futures are actually the past of other reference frames. This idea taken to one logical conclusion implies that there are places in the universe right now where only 1 second (as measured by sand trickling in an hourglass or the resonance frequency of cesium-133 atoms or whatever) has elapsed since the beggining of the universe. Meaning that for those 'observers' there is only one second of past and billions more years of future than for us, showing that what that perspective considers an open future with lots of potential but no set path (fate) we consider established indelible past with only one outcome (the outcome that happened). Basically I came to the conclusion that the concept of time, as we commonly understand it, with a past, present and future is flawed - that time is an illusion fabricated by our brains ability to change its activity patterns based upon the physical stimulus our body recieves (memories) creating an impression that those were events structured in some kind of sequential order dileneating past, present and future. If there was hypothetically a past that we could travel to, would that mean that there is, stored somewhere a copy of the entire universe in each state for every second, every micro-second, every nano-second (every smallest fraction of time you can think of) for the entire past (which we know is different for different reference frames)? That would mean there are infinitely many universes stored 'somewhere' that will be instantly 'activated' the moment something from its relative past/future enters it? Seems pretty unlikey and artificial to me. So to sum it up I came to the conclusion that time (past, present and future) doesnt exist, so time travel obviously doesnt exist. What are your guys thoughts? (give me some slack on the lack of organisation of my argument, it is very late (early) right now and I have been up all night)
"Repugnant is a creature who would Squander the ability to lift an eye to heaven, conscious of his fleeting time here" - Maynard Keenan

smd42
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Posted 04/04/08 - 07:27 PM:	#2
It seems that all those on these forums are night owls. ... I definitely am one. I agree. I don't believe that our theories of time are correct at all. They ARE technically but... Our idea of time is logical... but that's almost it's downfall. Our brains are wired to think a certain way, anything 'illogical' is impossible to imagine as our brain don't know perceive it as conceivable. Do you know what I mean? Like computer science. It's the language of logic basically, completely how our brain works. However, there may be a completely different side to the universe that we fail to see simply because our system of logic inhibits us. Sorry if this makes little sense. I'm still very bad at turning abstract thoughts into concrete words. I confuse myself.
He felt that his whole life was some kind of dream and he sometimes wondered whose it was and whether they were enjoying it. There is a theory which states that if ever anybody discovers exactly what the Universe is for and why it is here, it will instantly disappear and be replaced by something even more bizarre and inexplicable. There is another theory which states that this has already happened.

Carbon Based
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Posted 04/05/08 - 04:33 PM:	#3
Our brains are wired to think a certain way, anything 'illogical' is impossible to imagine as our brain don't know perceive it as conceivable. I don't beleive that is true at all. I think our brains are intuative. If I drop a 1 pound ball and a 25 pound ball off the roof, intution will tell you that the heavier object will hit the ground first. but we know that it is not true. Humans are good at recognising patterns, time is a pattern. Day, month, years are cyclic in nature.

Tad
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Posted 04/07/08 - 10:07 PM:	#4
My intuition tells me that something that was cannot be. It seems to be somewhat of a metaphysical principle. If X ceases to exist, then X cannot exist. I think time travel (TT) violates this principle; thus, TT is implausible. If Rome(X) was destroyed, then can Rome(X) exist? (No equivocation) I don't know where I am going with this. Any feedback?
Empty cages, not larger cages.

Tad
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Posted 04/07/08 - 10:13 PM:	#5
I'd like to reply more in depth. Give me a chance.
Empty cages, not larger cages.

Kingt2
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Posted 04/08/08 - 11:05 AM:	#6
I may respond more in depth at a later time, and after more contemplation as to the subsequent points; however, at this point, I wish to address only the point about the Grandfather Paradox. Allow me to restate the Paradox so as to maintain a certain flow of ideas, then: One can not travel back in Time and kill his own grandfather, for doing so would surely alter that time-line and obviously negate the events that lead up to his own birth. Thus, he would never have been alive to have gone back and kill his grandfather in the first place. I do not wholly agree with this idea. If one travels back in time --assuming such a thing is possible-- then that person becomes part of that time. One would not exist in, say, 2008, he would exist in whatever time he went back to. At that point in the past, the future hasn't happened yet, so one's birth did not happen, and anything is left to happen; and that person is part of that past, with just as much an open future as the rest of the population of that time. I maintain that if one were to go back in time and kill his grandfather, that the time-line would simply be altered; though I do not believe that a paradox would follow. The future of that time-line would not yield a you that travels back in time to kill his grandfather --because of course that person is never born, and the grandfather is already dead-- but that does not mean that he had not already traveled back. I believe that if one travels back and kills his grandfather, that he continues to exist in that time --since he exists as an entity of that time and not of the future of that time-line. I also believe that that time-line would continue as it would to a new --only slightly different-- future in which that person will likely have passed-on and would still not have been born, nor would he go back and kill --the already dead-- grandfather. That is an apparent paradox, but only on the surface. I think the idea of special relativity helps this idea out. [albeit barring the idea that time is immaterial --or at least un-alterable] If one point in the universe has only experienced 1 second of "time" since the beginning, and that point looks forward to a future that is our --supposed-- un-alterable past, it is conceivable that one might travel to that point and do something that might alter its future --and therefore, our past. Then, the past has been altered, however that point continues on its path towards its future [through our past]. Isn't it conceivable that that path would be significantly different than our known past --given a certain degree of compounding alterations; and yet we still exist as we do, while the past continues to be altered [or at least the relative past]. I will wait for a reply, or some feedback, for fear that my thoughts might become confused or sound like drug-induced pseudo-philosophy, or as I like to call it "Whoahh.." philosophy.
The most exciting phrase to hear in science, the one that heralds new discoveries, is not 'Eureka!' but 'That's funny...' -Isaac Asimov

Wosret
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Posted 04/17/08 - 08:08 PM:	#7
No.
"I am Horo the Wise." - Horo the Wise.

ugx2000
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Posted 04/18/08 - 04:59 PM:	#8
Indeed, the answer is - No.
An absolute peg in a subjective hole From the desert that is the human intellect. Retired.

perseus
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Posted 04/19/08 - 02:34 PM:	#9
DrNano wrote: Basically I came to the conclusion that the concept of time, as we commonly understand it, with a past, present and future is flawed - that time is an illusion fabricated by our brains ability to change its activity patterns based upon the physical stimulus our body recieves (memories) creating an impression that those were events structured in some kind of sequential order dileneating past, present and future. Doesn't this by definition imply the Brain is operating in a spatio-temporal framework. How else could something change its activity patterns? Perhaps a Brain could be 'wired' to be deceived in its sequential perception pattern relative to another Brain, but we have very little reason to believe they are. The consistency of certain physical phenomena relative to each other (allowing for relativity), and the communal Brain perception of these, provides the definition of time doesn't it? Isn't travelling backwards in time simply impossible so this removes the paradox?
The reasonable man adapts himself to the world; the unreasonable man persists in trying to adapt the world to himself. Therefore all progress depends on the unreasonable man. George Bernard Shaw

Wosret
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Posted 04/19/08 - 05:43 PM:	#10
Well traveling any direction in time is impossible. Unless you consider this.........................time travel. Past and future are concepts. Time is merely a dimension of space, we use our primate brains, that retain information to infer a past and a future, but all that exists is real time, and it is relative to your movement through space. Every moment of time is the present, suggesting one can travel to the future suggests that there are two seperate points that one could occupy; the present, and the future. This isn't the case, no matter how you are experincing the time dimention to the universe, you are always existing at the same moment in time as everything else that exists. Suppose you build a machine that allows you to approach speeds near the speed of light, and you us this to allow 400 earth rotations to passby, within a few minutes from your perspective. You were never not present for the passage of time, you did not "move to the future", at no time did you exit the present. All that changed was your relative relation to the passage of time. I am not saying that time is an illusion or anything, it is clearly part of reality as we know it. Nor am I saying that "past" and "future" are not useful concepts, they are, if used properly, in relationship to ourselves in real time. Though they are merely concepts, and do not exist without abstract thought, and minds to arrange events into a chronological order. Otherwise we merely have things effecting other things, in real time.
"I am Horo the Wise." - Horo the Wise.

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