• A question for Facepunch's finest
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This recently crossed my mind: At present, there are no rules of physics which prevent travelling backwards through time. If none are ever discovered, then it is a physical possibility and someone will, at some point, travel back in time. The scenario is this: In 4000 AD, someone travels back to 2000 AD. Whilst in the year 2000, he visits the crapper, or heck, just breathes. Whatever liquids/gases/particles leave his body will not return with him back to the future (assuming there isn't some physical law which returns everything to it's time of origin after a set period). This means that the universe now has a surplus of particles. Two thousand years then pass, and the time traveller is born, educated, employed, and transported back to 2000 AD, repeating the process. If this happens an arbitrarily high number of times, this increases the overall density of the universe, changing how it will end (heat death, big crunch etc.) My question is: how is this resolved? (I have a few ideas below, please don't click until you've had a long think) [sp]Our traveller shows up in 2000 AD and introduces, say, 1 kilo of matter from the future. Assuming they remain after he returns (or perhaps he doesn't return), two thousand years pass, and he travels again, to leave 1 kilo of mass behind. This means that for a two thousand year period, there is an extra kilo of mass in the universe, from 2000 AD to 4000 AD, after which it is removed. This means that the traveller is destined to travel back every time, making fate and destiny a mathematical proof, and throwing free will etc. completely out the window.[/sp] [sp]Alternatively, each time the traveller goes back in time, he actually travels to a parallel history/universe. Each time this happens, the extra kilo is left, and this racks up over many iterations. Eventually, one universe will become unstable and possibly be destroyed.[/sp] [sp]And finally, the one I've already mentioned, when the traveller returns, all particles from his time return with him. However, I don't know of any laws of physics which would support this, unlike the other two.[/sp]
The mass was already in the universe to begin with it just changes location in time.(On the temporal plane) and not on the xyz plane. Also mass can dialate time.
There is not an extra kilo of mass in the future, since he DID NOT defecate at one point in the future, meaning that there 1 kilo of poop simply exists earlier. Edit: Beaten to it.
I think if time travel was possible, It would create an alternate time line, since as discussed many times before, killing yourself in the past would be a paradox according to your theory.
[QUOTE=QwertySecond;26462420]This recently crossed my mind: At present, there are no rules of physics which prevent travelling backwards through time. If none are ever discovered, then it is a physical possibility and someone will, at some point, travel back in time. The scenario is this: In 4000 AD, someone travels back to 2000 AD. Whilst in the year 2000, he visits the crapper, or heck, just breathes. Whatever liquids/gases/particles leave his body will not return with him back to the future (assuming there isn't some physical law which returns everything to it's time of origin after a set period). This means that the universe now has a surplus of particles. Two thousand years then pass, and the time traveller is born, educated, employed, and transported back to 2000 AD, repeating the process. If this happens an arbitrarily high number of times, this increases the overall density of the universe, changing how it will end (heat death, big crunch etc.) My question is: how is this resolved? (I have a few ideas below, please don't click until you've had a long think) [sp]Our traveller shows up in 2000 AD and introduces, say, 1 kilo of matter from the future. Assuming they remain after he returns (or perhaps he doesn't return), two thousand years pass, and he travels again, to leave 1 kilo of mass behind. This means that for a two thousand year period, there is an extra kilo of mass in the universe, from 2000 AD to 4000 AD, after which it is removed. This means that the traveller is destined to travel back every time, making fate and destiny a mathematical proof, and throwing free will etc. completely out the window.[/sp] [sp]Alternatively, each time the traveller goes back in time, he actually travels to a parallel history/universe. Each time this happens, the extra kilo is left, and this racks up over many iterations. Eventually, one universe will become unstable and possibly be destroyed.[/sp] [sp]And finally, the one I've already mentioned, when the traveller returns, all particles from his time return with him. However, I don't know of any laws of physics which would support this, unlike the other two.[/sp][/QUOTE] But what happens to the timeline (4000AD) when the time traveler goes back in time? And what if he goes Back to the future, will he then be in an identical alternate future or the original future he came from? Wouldn't that mean that if he goes back to the future the mass he dropped in the past is not actually [I]more[/I] mass, seeing as he came back lighter into the future?
the universe in the future has a deficit of particles
Whenever the traveler introduces or reduces matter, the total is still the same, just at a different point in time, but not spatially.
As much as I admire you sharing your thoughts, you've got it all wrong. The whole grandfather paradox is pointless if you think about it enough. You are all thinking about this from the point of view of Marty Mcfly watching the professor scribble on that blackboard about timelines. For example: I go back in time 5 minutes and kill the past version of myself. I dont suddenly cease to exist because past me does not get to go back in time. The real end result is, the present (or future) me is now the current me and the past me is a dead body. The only bad by-product of this situation is that I have to hide a body, and if anyone finds out, a very awkward situation would ensue. The universe is not going to wrap itself into an infinite loop paradox just because I kill a past version of me. The universe would only recognize that there is another me, and I kill one of them. The universe's timeline will continue on as normal, with only a small side effect (dead body).
[QUOTE=taipan;26462438]The mass was already in the universe to begin with it just changes location in time.(On the temporal plane) and not on the xyz plane. Also mass can dialate time.[/QUOTE] So that matter which the time traveler consists of (in 4000AD), let's say that it in 2000AD was a part of a car (this is hypothetical and simplified, remember), would that chunk of the car simply disappear when the time traveler arrived?
the mass comes back in time with the time traveler, thereby removing it from the current = mass stays the same also, once the traveler brings the mass back in time, that mass has the ability to alter the current timeline, creating a NEW timelines where that mass wouldn't have existed in the first place but that's just a theory, meh
[QUOTE=QwertySecond;26462420]At present, there are no rules of physics which prevent travelling backwards through time. If none are ever discovered, then it is a physical possibility and someone will, at some point, travel back in time.[/QUOTE] Yes there are, nothing with a rest mass can travel at light speed (or faster.)
[QUOTE=Birdman101;26464550]As much as I admire you sharing your thoughts, you've got it all wrong. The whole grandfather paradox is pointless if you think about it enough. You are all thinking about this from the point of view of Marty Mcfly watching the professor scribble on that blackboard about timelines. For example: I go back in time 5 minutes and kill the past version of myself. I dont suddenly cease to exist because past me does not get to go back in time. The real end result is, the present (or future) me is now the current me and the past me is a dead body. The only bad by-product of this situation is that I have to hide a body, and if anyone finds out, a very awkward situation would ensue. The universe is not going to wrap itself into an infinite loop paradox just because I kill a past version of me. The universe would only recognize that there is another me, and I kill one of them. The universe's timeline will continue on as normal, with only a small side effect (dead body).[/QUOTE] Uh, no, if you were killed in the past you couldn't have gone back in time after that point to begin with. That is a paradox whether or not you want it to be.
[QUOTE=Birdman101;26464550]As much as I admire you sharing your thoughts, you've got it all wrong. The whole grandfather paradox is pointless if you think about it enough. You are all thinking about this from the point of view of Marty Mcfly watching the professor scribble on that blackboard about timelines. For example: I go back in time 5 minutes and kill the past version of myself. I dont suddenly cease to exist because past me does not get to go back in time. The real end result is, the present (or future) me is now the current me and the past me is a dead body. The only bad by-product of this situation is that I have to hide a body, and if anyone finds out, a very awkward situation would ensue. The universe is not going to wrap itself into an infinite loop paradox just because I kill a past version of me. The universe would only recognize that there is another me, and I kill one of them. The universe's timeline will continue on as normal, with only a small side effect (dead body).[/QUOTE] See, but you've altered the timeline by killing your past self anyway. If you kill your past self and life continues despite the temporal paradox, your past self can't go back in time to kill himself, and you're broken a stable time loop, throwing yourself into an alternate universe where you died at your own hands and you cannot ever return to the previous universe. You wouldn't become a paradox version of yourself and continue where you left off, as you have free will and you wouldn't be constrained to one sequence of events, unless you want to spend the rest of your life going back in time and killing yourself continuously.
no, the loop does not continue, it stops at the point where I kill my past self. I wouldnt be bending the timeline around in a loop, I would be cutting a chunk of it out and replacing it. Timelines DO NOT follow time travel. Time travel is going back and changing timelines. [img]http://img543.imageshack.us/img543/6681/whatyouthink.png[/img] [img]http://img686.imageshack.us/img686/7641/whatisreal.png[/img]
[QUOTE=Birdman101;26464802]no, the loop does not continue, it stops at the point where I kill my past self. I wouldnt be bending the timeline around in a loop, I would be cutting a chunk of it out and replacing it. Timelines DO NOT follow time travel. Time travel is going back and changing timelines. [img_thumb]http://img543.imageshack.us/img543/6681/whatyouthink.png[/img_thumb] [img_thumb]http://img686.imageshack.us/img686/7641/whatisreal.png[/img_thumb][/QUOTE] You literally have no idea what you are talking about. Stop complicating the argument with your nonsensical ideas about the geometry of timelines. When you go back in time and kill yourself in the past, you set it up so that you can never have traveled back in time because you die before you do so. [editline]3rd December 2010[/editline] You are making assertions that go against good reasoning without anything to back them up except "you're wrong this is how it really works"
Because of all these weird paradoxes I concluded: travelling to the past is not physically possible. The concept only exists because we have memories. But it's always fun to think 'what-if'.
[QUOTE=Clavus;26465226]Because of all these weird paradoxes I concluded: travelling to the past is not physically possible. The concept only exists because we have memories.[/QUOTE] No, the concept exists because of the existence of closed timelike curves in general relativity. As far as we know, nature allows for the possibility of time travel until we discover otherwise.
Johnnymo1 knows his time travel shit bro He keeps a mean library of Lovecraft books, too. (and likely a spiffy dresser)
[QUOTE=JohnnyMo1;26465070]You literally have no idea what you are talking about. Stop complicating the argument with your nonsensical ideas about the geometry of timelines. When you go back in time and kill yourself in the past, you set it up so that you can never have traveled back in time because you die before you do so. [editline]3rd December 2010[/editline] You are making assertions that go against good reasoning without anything to back them up except "you're wrong this is how it really works"[/QUOTE] Its a theory You have no more evidence that you are right than I have to prove my point. But if you ask me, you are just going along with every other idiot who thinks they know time travel because you are too ignorant and closed-minded to think up your own theories.
ITT: A lot of people who are certain that their time-travel theory is right while the others are wrong. Time-travel is a very unexplored field of physics. So far, the only kind of "time travel" we have observed is slight time dilation, so we have no idea what will happen when someone goes [B]back[/B] in time, hell, we don't even know if it's possible to go back in time (although our current knowledge of physics says that there is nothing to prevent it, we could be wrong). What I'm trying to say is that we know very, very little (almost nothing) about this, so to say "No, you're wrong, THIS is how it will be if I killed my grandfather" is plain arrogant.
The matter is always there, just transformed throughout its lifetime (maybe?)
You can "slow" time by speeding up time for yourself by going near a black hole. Of course, when you get sucked in, you'll be ripped apart, but the concept is if you spent a few years immediately next to a black hole, everyone you know would be dead. I personally think going back in time is an impossibility.
Isn't time a human construct that is comprised of the rate of physical reactions? We can slow the rate at which the reactions occur, but why would it follow that we would be able to reverse physical reactions?
[QUOTE=that1dude24;26466062]Isn't time a human construct that is comprised of the rate of physical reactions? [/QUOTE] no
I think the answer is you should probably get out more.
[QUOTE=Flapadar;26466134]no[/QUOTE] I could definitely be missing something, but I haven't come across anything that proves time as a physical constant rather than a construct.
[QUOTE=that1dude24;26466298]I could definitely be missing something, but I haven't come across anything that proves time as a physical constant rather than a construct.[/QUOTE] [URL]http://en.wikipedia.org/wiki/Spacetime[/URL] [URL]http://en.wikipedia.org/wiki/Special_relativity[/URL] [URL]http://en.wikipedia.org/wiki/General_relativity[/URL] Time does exist. So does time dilation (it's even been observed, modern satellites have to be adjusted for time dilation due to their speed and low gravity in orbit), which further proves the existence of time as a dimension. However, it could be argued if it's possible to travel back in time.
[QUOTE=that1dude24;26466298]I could definitely be missing something, but I haven't come across anything that proves time as a physical constant rather than a construct.[/QUOTE] It's not a physical constant, it's a dimension.
[QUOTE=taipan;26462438]The mass was already in the universe to begin with it just changes location in time.(On the temporal plane) and not on the xyz plane. Also mass can dialate time.[/QUOTE] [QUOTE=macacan;26462446]There is not an extra kilo of mass in the future, since he DID NOT defecate at one point in the future, meaning that there 1 kilo of poop simply exists earlier. Edit: Beaten to it.[/QUOTE] I think I get what you’re saying. Assuming our traveller dies in the past, his entire mass (let’s say 100Kg) remains on the timeline, adding to the overall density of the universe. In 4000AD he time travels, removing the excess 100Kg. This means that he [i]must[/i] travel in order to keep the universe stable, which is essentially destiny. [QUOTE=DarkWolf2;26462459]But what happens to the timeline (4000AD) when the time traveler goes back in time? And what if he goes Back to the future, will he then be in an identical alternate future or the original future he came from? Wouldn't that mean that if he goes back to the future the mass he dropped in the past is not actually [i]more[/i] mass, seeing as he came back lighter into the future?[/QUOTE] Similar to above. I’ll use this graph to see if I understand what you’re saying. [img]http://i913.photobucket.com/albums/ac332/QwertyTSecond/timetravel.jpg?t=1291477854[/img] Here we have three graphs, where X is time and Y is mass (not to scale). On the first, the black line indicates an unchanging mass. On the second line, the traveller goes back in time and returns (for clarity I’m showing his time displacement as constant, i.e. he can’t return one second after he leaves). The mass delta is shown in red. In the past, he increases the mass. When he leaves, the mass returns to 0 delta. The third graph is what you’ve said. The mass he leaves behind when he returns to the future is shown in blue. Since he comes back weighing 99Kg, this cancels out the 1Kg of extra mass which has existed for 2000 years, returning delta to 0. This method still results in the traveller being required to go back in time, i.e. destiny. [QUOTE=Ultralast;26464664]the mass comes back in time with the time traveler, thereby removing it from the current = mass stays the same also, once the traveler brings the mass back in time, that mass has the ability to alter the current timeline, creating a NEW timelines where that mass wouldn't have existed in the first place but that's just a theory, meh[/QUOTE] So you’re more inclined to go with my third option? In which case, any idea what sort of phenomena would cause that to take place? [QUOTE=JohnnyMo1;26465250] [QUOTE=Clavus;26465226]Because of all these weird paradoxes I concluded: travelling to the past is not physically possible. The concept only exists because we have memories. But it's always fun to think 'what-if'.[/QUOTE] No, the concept exists because of the existence of closed timelike curves in general relativity. As far as we know, nature allows for the possibility of time travel until we discover otherwise.[/QUOTE] Indeed. Proposed methods include colliding cosmic strings and Tipler cylinders. They are far, far beyond anything our current engineering ability is capable of, but they are mathematically sound and could one day be created. (On a side note for all you readers, it is technically possible to go faster than light, using something known as an Alcubierre drive.) And finally, Birdman101, I really can’t debate paradoxes with you, other than using cause and effect. For example, a rocket will not spontaneously pop into existence (effect); it has to be built (cause). Similarly, your grandfather has to exist in order for you to be born (cause). If you kill him, that removes the cause, and there can be no effect (unless we bring parallel timelines into the equation). For more info, I recommend looking up the Novikov self consistency principle.
[QUOTE=Mindtwistah;26465707]So far, the only kind of "time travel" we have observed is slight time dilation, so we have no idea what will happen when someone goes [B]back[/B] in time, hell, we don't even know if it's possible to go back in time [/QUOTE] [url=http://www.facepunch.com/threads/1029484-Quantum-Time-Travel-Experimentally-Shown-%28sort-of%29-Grandfather-Paradox-solved-%28sort-of%29]uhhh[/url]
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