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B Are photons really necessary in physics?

  1. Nov 11, 2016 #1
    I've read two articles about the historic development of the concept of photon and how some effects which originally were explained using photons have been later explained by other means.

    And after this two quick readings I have a lot of questions. First of all, do we really need a concept of photon in order to explain quantum physics? Second, if that's the case then what it's exactly a photon? And finally, can we develop an experiment to decide which of our models is the "correct" one?

    I know it's somewhat a philosophical question, but so was the hidden variables theories before Bell.

    I would greatly appreciate any reference to discussions and papers related to this mater.

    Thank you all in advance.

    P.S. The articles I talk about are
  2. jcsd
  3. Nov 11, 2016 #2
    Suggest you construct clear individual questions and make a thread for each over on the relevant main boards.
  4. Nov 11, 2016 #3


    Staff: Mentor

    We need a quantum EM field to explain spontaneous emission:

    Chug through the math as in the above and photons are inevitable.

    Note - photons as described in populist literature is not the real deal found in Quantum Field Theory.
  5. Nov 12, 2016 #4


    Staff: Mentor

    "The concept of photon" is much too vague. We need a quantum field theory that includes the electromagnetic field; that's clear from experiments that cannot be explained any other way. (Bhobba mentioned spontaneous emission; another that comes to mind is the Lamb shift.) So if that's what you mean by "a concept of photon", then yes, we need it.

    If you want to understand the quantum field theory of the electromagnetic field, you should not start with this question. You should start with the basics of quantum electrodynamics: what is a quantum field, how do we construct a quantum field that has the right properties to model the electromagnetic field, etc. The concept of "photon", to the extent it turns out to be useful, will emerge from all that. In other words, "photon" is not a fundamental concept; the fundamental concept is "quantum field".
  6. Nov 12, 2016 #5

    A. Neumaier

    User Avatar
    Science Advisor

    We don't need it to explain quantum physics but to explain antibunching in the statistics of certain experiments involving nonclassical light.
    For references see the article What is a photon? and other topics in Chapter B2: Photons and Electrons of my theoretical physics FAQ.
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