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Doesn't QM allow for FTL travel?

  1. Aug 13, 2008 #1
    My knowledge of QM is far from great, but I can't figure out what I'm missing here.

    When looking for e.g. an electron, it has a certain probability to be at a certain location, right? So how does *not* this allow for the electron to travel faster than light?

    If I take two measurements, one taken with a tiny, tiny delay, couldn't I potentially find the electron at one spot with the first measurement, then with the second measurement find it on the completely opposite side, further away than light could have travelled within that small time-delay between the measurements?
  2. jcsd
  3. Aug 13, 2008 #2
    I understand what you're saying, but I'm still not sure how this rules out ftl travel. Granted, the electron might not 'travel' as such, but if it appears at a location more distant than one which light could have travelled in the time between measurements, even if the electron itself didn't travel there but rather 'teleported' to or 'was found there', then it has effectively covered that distance faster than the speed of light, right?
  4. Aug 13, 2008 #3


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    I'm sorry, Raap and everyone else. I deleted my message since I wasn't happy with my explanation. I had hoped you hadn't read it yet, since I found it to be just confusing. Sorry for making the thread confusing by it's deletion.

    I have found this past thread that may be of help to you. Check out Zapperz's post.



    Here is another paper discussing "superluminal tunneling" written by an author of a paper mentioned in the thread above:

    H. Winful, Phys. Rep. v.436, p.1 (2006).

    I think the best I can do is to provide you with this "reading list" of threads and papers.:rolleyes: I'll leave the discussion and explanation to someone with more experience explaining the effect.
    Last edited: Aug 13, 2008
  5. Aug 13, 2008 #4
    Sure, it will have 'traveled' faster than light if you see it here than there in a short time. But if your going into the muddy details remember that relativity says you cannot 'communicate' faster than light. Specific conditions can be contrived where objects appear to be traveling faster than light and that's fine, because you still cannot communicate faster than light and causality is maintained.
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