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B A Possible Challenge To Chronology Protection Conjecture?

  1. Apr 9, 2017 #1
    Correct me if I am wrong, but my basic understanding of how the Chronology Protection Conjecture (CPC) would work is that, as virtual particles created from the quantum fields of the vacuum would traverse a wormhole and arrive in the past, they would then travel back into the wormhole alongside their past self, doubling the amount of energy entering the wormhole, and this process would continue, ad infinitum, until there is so much radiation traversing the time machine that it is destroyed.

    However, this scenario does not make sense to me. I have thought of an objection to it. This is that, once the photon (for example) enters the wormhole and arrives in the past, what would compel it to join its past self in, once again, traversing the wormhole? To furnish an analogy, let's say a human builds a restaurant, and then, once finished, travels back in time through a wormhole to see their past self building the restaurant. However, there is nothing to compel them to assist their past self in building the restaurant, as their past self is already doing it.

    I feel that the same would apply to the radiation that is supposed to build up in this process and destroy the wormhole before it can be utilized as a time machine. In other words, I am saying that there is no reason to suppose that the virtual particle would necessarily join its past self in traversing the wormhole, and, thus, no reason to necessarily suppose that radiation would build up in the wormhole until it destroys it.

    Does anyone notice any glaring flaws or errors in my argument? If so, please point them out, so I can either account for them or, if my original hypothesis turns out to be unsalvageable, to admit I am wrong on this point and discard it, in the spirit of empirical scientific investigation. Thanks.
  2. jcsd
  3. Apr 9, 2017 #2
    I had to read up on it first, but the way I understand it now is that, if there *were* to be a chronological violation (I.e. a paradox), the two mouths of the wormhole would need to be close enough to each other so that a particle that exited mouth B in the past, can, within the bounds of relativity, make it to mouth A before the particle had entered it there. So, the scenario is:

    1. Particle enters mouth A of wormhole
    2. Particle travels through wormhole
    3. Particle exits at mouth B, but now in the past
    4. Particle travels to mouth A, arriving *before* 1. happened

    That would be the requisite for the violation, because if the particle couldn't get back to A in time, it couldn't cause a violation if it tried.

    Now, the way I understand it, the censorship hypothesis essentially say this constitutes a feedback loop. After the first time travel, you now have *two* particles, which would then enter mouth A. This would obviously escalate to infinity.
    The bone of contention in research seemed to have been that for normal particles, they would "defocus", thus not making it back into mouth A. But, for those virtual particles, they somehow refocus, and that's where the censorship mechanisms would kick in. That is, even barring any nefarious attempts, the normally occuring virtual particles would create this feedback loop, thus immediately destroying the wormhole.

    This is all crazy hypothetical though. It all rest on using theories in areas where we know they might not apply. I find these discussions interesting, but more in the sense of probing where our current theories fall apart.
    Last edited: Apr 9, 2017
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