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View Poll Results: Do you think time travel could work?

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Thread: How Time travel works

  1. #1 How Time travel works 
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    Time travel. though some people might call it science fiction and completely ludicrous it is actually earning allot of attention by many of the worlds leading scientists such as stephen hawking and Michio Kaku. It grips are imaginations and stimulates are minds. and today By using information gained from these gents I'm going to explain how time travel could be done.

    Time travel to the future- The speed of light is 299 792 458 m/s. Nothing can go faster then this. it is a universal speed limit. However if you had a train that went 99.99.99 percent of this speed something very weird would happen. lets say a kid runs on the train. there speed pluse 99.99.99 Percent of the speed of light would make them go faster then light right? wrong. everything inside the train would slow down to near no movement the closer you got to the speed of light. because the inside of th train is going very slow well everything outside is going very fast you could hypothetically travel 100 years into the future within a few days on this light train.

    Time travle to the past- suppose you had a gun and a time machine. you load the gun and go back in time. once there you kill yourself well loading the gun. but if you never loaded the gun and went to the past then who on earth just shot you? this is called a paradox. a paradox is a statement that appears self-contradictory. Now heres a bit of information from my favoret theoretical physisist Michio Kaku. or more to the point quoted by him.

    "Time is like a river. It flows one direction, always. this was told by sir Albert Einstein.

    HOWEVER the new twist is that the river of time can have whirlpools or even fork into two different rivers. now lets go back to our story about the man with the gun. who shot him? the real question is who did you just shoot? Michio Kaku clames that
    you did not just shoot yourself but yourself from a different reality more commonly known as a parallel universe. though this is far fetched we can look at electron theory here. an electron moves so fast around an atom that it is in fact in two places at once. this rips time causing one reality to have an atom in one spot and another reality to have the electron in another. so there is in fact an infinite number of reality's co existing in other reality's. so you didn't travel back into your own "river of time" you in fact traveled to another "river of time" and shot someone who is biologically and physically you. but its not you. its you in another reality.

    Now more importantly how would one go about making a time machine? well the most commonly used idea is a wormhole. the theory of general relativity states that mass causes space to curve. picture are dimension of a peace of paper. the paper is not perfectly flat but has wrinkles in it caused by mass. the more mass something has the more it curves space. in some cases space can curve in such away that it links two seemingly distant locations to each other. however because time and space are mashed together you could go to another time as well. the only problem about making one is that the radiation it produces would feed back upon itself. eventually the wormhole would "devour itself".

    Finally lets look at one of the last possible ways of time travel. mass causes time to lag. we know this to be true because the world wide global positioning system (or gps) slows down oh so slightly because it is further away from the earth. a good way to look at this is suppose you had a mass that weighed as much as the black hole at the center of the milkyway galaxy. by being near it you would move at only one half the speed of things on earth. so you would slow down and in effect everything around you would speed up thus causing time travel. one could argue that because it is the mass of something that is slowing the time that you are in fact not traveling through time but entering a location of slower time then the area around it.

    Now even though these ideas seem really straight forward there are some proposed paradoxes. proposed by stephen hawking "well if there are time travelers then ware are they? don't they want to meet me?" this goes back to the idea of parallel reality's. if you went back in time to meet him (witch as i said before i don't think is possible) then you didn't go to meet him in are timeline but in fact to another reality to meet him. it prevents paradoxes so anything you did in the past wouldn't hurt the future.

    So as you can seeeeeee. time travel though scoffed at by some is actually rather simple in itself. But on a cliffnote I would like to throw an idea of mine into the hat.
    a tachyon witch is a hypothetical state of matter that has no mass and moves faster but not slower then light moves faster then light right? well if moving near the speed of light slows down time then wouldn't moving faster then light make you go backwards?


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  3. #2  
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    I might not be the only one to suspect that speculation which involves parallel universes and wormholes probably is science fiction. It's not just that I am a grumpy old man - these things just haven't been observed.

    For some reason, Physics appears to be particularly susceptible to scenarios of the sort referred to. Please forgive me if I appear to be critical - it's just that such extraordinary extrapolations don't seem to crop up in areas such as Chemistry.


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  4. #3  
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    Time travel to the future is simple enough. It happens all the time to everyone. Time travel to the past is impossible because if it wasen't someone from an advanced future generation would have visited us to try and 'correct' some wrong.

    But seriously, at an elementary level, every possibility is available, a superposition of states described by the wave function. when an observation is made the wave function collapses to the one observed state ( see Shroedinger's cat). It is then impossible to go 'up-river' and recreate this sum of all possibilities in the uncollapsed wave function. So time only travels in one direction.
    There is some speculation that all differnt possibilities collapse into different realities (see multiple/infinite univeses), but this tree structure spreads into the future, so that changing your past would just shoot you down a different branch where the results are normal, not your own original branch.
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  5. #4  
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    Quote Originally Posted by MigL
    Time travel to the future is simple enough. It happens all the time to everyone. Time travel to the past is impossible because if it wasen't someone from an advanced future generation would have visited us to try and 'correct' some wrong.
    This depends on which theory of time travel you subscribe to. If you believe in the self-consistent version, (that time travel is possible, but only when it leads to a non-contradictory time-line), then future visitors might be showing up all the time, but totally incapable of changing their own known history.

    If they try to reveal themselves, then they get smacked back into the future.


    But seriously, at an elementary level, every possibility is available, a superposition of states described by the wave function. when an observation is made the wave function collapses to the one observed state ( see Shroedinger's cat). It is then impossible to go 'up-river' and recreate this sum of all possibilities in the uncollapsed wave function. So time only travels in one direction.
    Depends how you interpret Schroedinger's cat. The way I look at it, the reason the cat is both dead and alive until you open the box is that it hasn't been determined yet. When you open the box, you determine what state the cat is in by looking at it, causing the wave function to collapse, and causing the cat to have been in a consistent state the whole time.

    The story only seems silly if you refuse to accept backwards time causality. Otherwise, the story makes perfect sense. The box is a special case of a situation where a past event (for most of us) lies in the observer's future.
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  6. #5  
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    Quote Originally Posted by kojax
    But seriously, at an elementary level, every possibility is available, a superposition of states described by the wave function. when an observation is made the wave function collapses to the one observed state ( see Shroedinger's cat). It is then impossible to go 'up-river' and recreate this sum of all possibilities in the uncollapsed wave function. So time only travels in one direction.
    Depends how you interpret Schroedinger's cat. The way I look at it, the reason the cat is both dead and alive until you open the box is that it hasn't been determined yet. When you open the box, you determine what state the cat is in by looking at it, causing the wave function to collapse, and causing the cat to have been in a consistent state the whole time.

    The story only seems silly if you refuse to accept backwards time causality. Otherwise, the story makes perfect sense. The box is a special case of a situation where a past event (for most of us) lies in the observer's future.
    The cat's condition is unknown, but the cat's condition is already set. The quantum thought experiments aren't as intricate as you'd like to believe, kojax. They don't allow for time travel to the past, in any way. "Backwards time causality" is non-scientific, and as such, very dismissible. There simply is no reason to believe it exists in any way.
    Wise men speak because they have something to say; Fools, because they have to say something.
    -Plato

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  7. #6  
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    this all really depends on the theory that you're trying to talk about. because garatto was talking about all the different possibilities of how time travel could work there is no single good response to his post.

    however i'm somewhat familiar with the theory of wormholes that send you back in time. in order for a wormhole to send you back in time it must have such a strong gravitational pull that it curves the whole of spacetime around it so that it creates a short tunnel from one point to another that would have been a long distance away on a flat plane. observe:


    now, whoever drew that for me wanted to show a wormhole that takes you from one place in spacetime and go to another place in spacetime through a shorter distance. but because spacetime consists of space as well as time, you could just as easily have gone from one position at one time to the same position at a previous time. so rather than having A and B represent earth and a far away galaxy, you could say that the A represents earth now, and B respresents earth 100 years in the future.

    so, if i were to go from A to B through the wormhole i'd have gone 500 years into the future in as long as it takes me to go through the wormhole. now most people don't start whining about causality when i travel into the future that way, but when my great great great great... grandchildren decide they want to go back 500 years and kill pappy before he has any children, uh oh(and not just because such a great guy is gonna die). this is supposed to pose a problem in causality.

    now i don't have much to say about the other theories but i can most deffinately clear up this paradox. because the fabric of spacetime(everything that exists when viewed outside of time) does not change over time(time does not progress outside of spacetime) this means that viewed from a theoretical god's perspective, their decision to go back in time and kill me didn't actually change the past. in reality if they were successul in going back through the wormhole then the past would have already reflected everything that would have occured in their future.

    now as someone already pointed out, the fact that we don't already see evidence of people coming through wormholes to try to affect us means that it is probably impossible to travel back in time, either that or it has happened numerous times leaving us with unexplained or unnoticed events throughout our history. in either case no paradox arises when asking what would happen if someoen traveled back in time through a wormhole.
    physics: accurate, objective, boring
    chemistry: accurate if physics is accurate, slightly subjective, you can blow stuff up
    biology: accurate if chemistry is accurate, somewhat subjective, fascinating
    religion: accurate if people are always right, highly subjective, bewildering
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