The point is you can't send an instantaneous message [such as a message which gives information about an event which hasn't happened yet {no causal relationship can exist which requires information to propagate faster than the speed of light}] using quantum non-local effects.

Well, I understand the conclusion, it is arriving at that conclusion with respect to the thought experiment that is perplexing to me. That is, if the first thought experiment where Bob reaches M31 and sends an instant message to Alice is allowable, and then Bob does the same kind of messaging in the second thought experiment, but this time going at 80% the speed of light, then the question is - what prevents causal loops as long as the quantum experiments are performed in a legitimate matter?

I read even section VIII, but the point that I extracted from that paper (with respect to non-local entangled particles) is that quantum randomness prevents non-local signals to be used as a signal that carries a message. The thought experiment that I mentioned does not suffer from this problem since it uses mutually exclusive entangled states (with one particle state being more probable if the wave function is 'collapsed' by measurement). This difference in probability of the collapse is what is being exploited by the sender to the receiver. However, if this is really possible, then it would seem that instant messages could violate special relativity.

I guess what I'm asking is what do you see faulty in either or both of these thought experiments. Surely, it can't be going 80% the speed of light (in terms of a thought experiment). It can't be entangled particles that are mutually exclusive at non-local distances (since this has been done in experiments). What is it specifically that is faulty with these thought experiments?

• I've already mentioned what was wrong with.. - bruce - October 28, 2003 - 20:25 UTC
  • Maybe I didn't catch that... - harvey1 - October 28, 2003 - 20:57 UTC
    • ...we are communicating vast distances - harvey1 - October 28, 2003 - 21:00 UTC
    • It strikes me as a message... - bruce - October 28, 2003 - 23:23 UTC
      • Well... - harvey1 - October 29, 2003 - 04:10 UTC
        • The limit appears to be... - bruce - October 29, 2003 - 04:43 UTC
          • I don't think we can - harvey1 - October 29, 2003 - 13:01 UTC