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Wave-Particle Duality and Particle Specific Identification

  1. May 28, 2014 #1
    I have been struggling with one simple question. How can one measure the momentum of a particle within a field without disrupting the entire field, all together? If the particle is under observation at at t_0, how is it verifiable that at t_1 the same particle is being observed? Obviously spin and the state of the field can be determined in certain instances, but is it presumptuous to assume that the observed particles are identical?
  2. jcsd
  3. May 28, 2014 #2


    Staff: Mentor

    Of course you cant say anything about a particle when its not observed. When you observe it next who knows if its the same particle or what it is. QM is silent about any of that. But why make life hard for yourself and the world weirder than it has to be. Its easiest assuming its the same particle so simply do that.

    If you are just starting out in QM I suggest the following:

    QM is in fact an approximation to a deeper theory called Quantum Field Theory. By treating everything as a field a number of conceptual issues disappear and is how I suggest you start out. The above book is quite good and unique in its approach. Although some comments he makes about Feynman are off the mark. He attributes Feynman's comment about the shell game played with field theory to field theory itself - it wasn't - it was with regard to renormalisation which has now been resolved through the work of Wilson and others on effective field theory.

    Last edited by a moderator: May 6, 2017
  4. May 28, 2014 #3
    Thanks Bill

    I am somewhat new to the concepts, so it would be ideal for me to gain a better understanding. I am an applied mathematics major with possible interests in multivariate public key cryptography. I noticed "spin" seems to be the central focus of the available research.
  5. May 28, 2014 #4


    Staff: Mentor

    Last edited by a moderator: May 6, 2017
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