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Thread: Worm holes and time travel

  1. #1 Worm holes and time travel 
    Forum Radioactive Isotope MagiMaster's Avatar
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    I know that IRL, FTL equals time travel, so I was wondering about how this applies to worm holes? Is there any restrictions that can be placed on the space-time positions of the endpoints to prevent any meaningful time travel (closed time-like curves)? For example, making sure that the two endpoints lie within each others light cones? Or would it be outside each others light cones? (I'm not very good at imagining space-time diagrams.) Would these restrictions be enough to prevent a network of worm holes from creating closed time-like curves?


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  3. #2  
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    IMHO wormholes are an abstraction that simply cannot exist. The underlying problem is that a mathematical space (eg Minkowski spacetime) is not what actual space is.


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  4. #3  
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    Well, my specific question requires the assumption that wormholes can exist. The question is more of 'what theoretical limits could be placed on wormholes to prevent closed time-like curves'. Whether or not wormholes actually exist IRL doesn't really matter for such theoretical questions anyway.
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  5. #4  
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    Quote Originally Posted by MagiMaster
    Well, my specific question requires the assumption that wormholes can exist. The question is more of 'what theoretical limits could be placed on wormholes to prevent closed time-like curves'. Whether or not wormholes actually exist IRL doesn't really matter for such theoretical questions anyway.
    Your question is on the level of if Santa Clause can make it around to all the houses in one night the how does he get into those half billion homes without a chimney.

    As soon as you negate the physical properties of the universe (as in a 'what if' assumption) then all else becomes nonsense.
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  6. #5  
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    I don't actually see the problem with his question. GR allows for the possibility of wormholes so while it's definitely "out there" as a concept, I don't think Santa Claus is a fair comparison.
    Although, I don't think I'd consider wormholes as "FTL" in any way. Mass going through a wormhole would still be travelling slower than the speed of light locally, it's just "taking a shortcut" to get to the new location.
    I also have no idea what the properties of possible wormholes are or if it's even possible for massive objects to travel through a wormhole.
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  7. #6  
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    I thought this entry on wiki was pretty interesting:
    Chronology Protection Conjecture
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  8. #7  
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    Quote Originally Posted by Neutrino
    I thought this entry on wiki was pretty interesting:
    Chronology Protection Conjecture
    Google and find anything. It doesn't prove a darn thing

    http://en.wikipedia.org/wiki/Santa_Claus
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  9. #8  
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    What does "prove" have to do with it? They may not exist, but GR hasn't ruled it out either. It's a possibility.
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  10. #9  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Here's another link. Let me rephrase my question: Assuming traversable wormholes exist, are there conditions that can be placed on the endpoints that prevent closed timelike curves and what might those conditions imply? Since the endpoints of wormholes exist in space-time, an unconstrained wormhole does allow closed timelike curves.

    For example, can a closed timelike curve be created if the wormhole's two endpoints are outside of each others light cones? If so, is it possible for humanity to place two objects in such a way? (I'm not very good with SR, much less GR.)

    Also, since I'm asking this question under the assumption (in the mathematical sense) that wormholes exist, this isn't the place to debate their existence. That's an entirely separate question.

    Edit: BTW, this question is fairly similar to, 'Assuming Santa Clause exists, how does he get to all the homes?' and lots of people have fun trying to answer that question too. Whether or not Santa does exist is irrelevant.
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  11. #10  
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    Magi did you check out the link I gave? Hawking talks about some of that stuff
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  12. #11  
    Forum Radioactive Isotope MagiMaster's Avatar
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    Yeah, but it didn't explain some things in detail.

    How about a more straight-forward question then. Can a set of wormholes be used to create a closed timelike curve be created if no wormhole is allowed to have both endpoints in each others light cone?
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