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The failure of so-called no-communication theorems

  1. Jun 1, 2012 #1
    The failure of so-called "no-communication" theorems

    In what we commonly refer to as "no-communication" theorems of quantum mechanics (QM), we make assumptions which are consistent with QM and with our knowledge of physical systems. But are these assumptions appropriate to a potentially would be faster-than-light (FTL) protocol for physics.
    Let's first assume that out there in the mind of some brilliant young physicist (possibly not even born yet) is the real FTL protocol. If this is the case, then we must ask, are the assumptions of no-communication theory correct, and if they are correct are they appropriate to the FTL protocol? Do these assumptions cover all possible setups for such a protocol and show that within all setups there is no allowance for FTL? No.

    First of all, most no-communication theorems assume an entangled system is the way to go. But is it though? These theorems are a reaction to the EPR/Bell type thinking. But QM had non-locality before EPR(1935) and Bell(1960's) showed up. QM has always had interference between optical pathways, even if the optical pathways are separated by more than the uncertainty in position, as long as the optical pathlengths differ by no more than the uncertainty in position. Some how the coherent superposition is retained even though the paths are separated by a length longer than the uncertainty. As long as the "which path" information is not present in the preparation.

    Hmmm, has any of these so-called "no-communication" theorems made up a rule in QM about "which path" information and then assumed this rule in the setup of the theorem. I think not. To put it bluntly, all no-communication theorems simply use "in the box" type assumptions and then low and behold, there is no FTL communication in the box. But if they venture outside of that box they just might become that great young theorist yet.

    In general, al onestone states that it makes no sense to make an assertion about what one "cannot" achieve, because it only expresses the limitations of current theory.
  2. jcsd
  3. Jun 23, 2012 #2


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    Re: The failure of so-called "no-communication" theorems

    FTL in quantum entanglement is impossible by definition - an operational definition. So far, we know that the statistical comparison between the quantum states of Alice and Bob must be completed by a classical channel, limited to the speed of light.

    If that 3-criteria brain: “brilliant, young, physicist” can figure out how to modulate Alice’ quantum state, there will be no need for a comparison A-B, and hence no need for a classical channel. The signal-to-noise ratio will be high enough for Bob to compare the output with his own memory. I'm sure that even if Bob isn’t proficient in music, he will be able to distinguish Mozart's Symphony No. 40 in his headphones from random quantum noise. As I humbly see it.

    However, the main task of a research team, research unit or university is never written down in the charter, statutes or paragraphs. The main task is to survive, and a life outside the box is not compatible with life in the long run.

    My experience is that many scientists think outside the box too, but we can’t act outside the box. That’s the difference. I highly recommend that 3-criteria brain to make his academic career in the box, but silently do his secret experiments in the garage, funded by the rich uncle.
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