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Entanglement and communication speed

  1. May 20, 2010 #1
    I was just reading the new article that saying that people sent information through entangled photons, and that the photons were 10 miles apart. when entangled photons change they do so instantaneous of each other. so does this mean that even though they were ten miles apart they reacted to each other at the same time. how does this work, while still retaining that nothing can travel faster than the speed of light.
  2. jcsd
  3. May 21, 2010 #2


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    There can be no information transfer without a classical channel to communicate with. Therefore, no FTL information transfer is possible even with entanglement. Yes, the entangled particles may react "instantaneously" to the other being observed, but someone with only 1 of the entangled particles will never be able to see more than just random bits from it. You need to have information on both the particles to verify that they were in fact anti-correlated.
  4. May 21, 2010 #3
    The states change instantaneous. Even Einstein wondered about this instaneous change and he called it "spooky action at a distance".

    But you can't use it to send information faster than the speed of light. That is because you cannot for example "force" the photon to have vertical polarization

    More on "spooky action at a distance" can be found here:
    1) Whyfiles: Entangled Up in Twos
    2) Wikipedia: Action at a distance
    3) Spooky action and beyond: Interview with Anton Zeilinger
    4) Spooky action at a distance? Blog post by Steve Luttrell
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