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My physics textbook says that photoelectric emission provides conclusive evidence for the particle theory of light. Apparently, since photoelectric emission only works at certain frequencies, we can conclude the electrons do not build up the energy from the light and thus the light energy must not be reaching the electrons as a continuous wave but rather as discrete particles called photons. However, wouldn't energy build up also not occur if we considered light as wave pulses instead of particles? If so, why is it then that we insist it is a particle? Or is it a wave pulse but just called a particle? If it is, then why?

Chryron
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    Well, your textbook means well while it is telling you a "lie for kids". The photoelectric effect is evidence for the quantum nature of light, not for the corpuscular theory of light, which is simply false. Unfortunately, the only truly correct theory of light, quantum electrodynamics, is pretty complicated, so we can't teach it at this level. Suffice to say, it's a field theory. Every older model of light (wavelets, corpuscles, ray etc.) can be derived as different kinds of approximations from it. – CuriousOne Apr 02 '16 at 14:47
  • @CuriousOne - Has anyone ever tried to write a book that accurately explains such things but is meant for undergraduate level students? Or is it too math intensive and would require too much background? I noticed by the end of grad school that I had been fed numerous statements that later turned out to be "lies." I always felt it would have been more useful just to hear the correct answer immediately even if I did not understand it... – honeste_vivere Apr 02 '16 at 15:23
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    @honeste_vivere: I think Feynman did a fine job in describing the inner workings of quantum electrodynamics in "QED: The Strange Theory of Light and Matter" without the need of complicated math. It's not a physics textbook by any means, of course, but the "interpretation" of quantum mechanics in terms of path integrals is, I think, a very useful addition to ones mental imagery. I do agree, by the way, that the "lies for kids" need to stop. Repeating the dusty failed concepts of three centuries in chronological order is not the right way of educating students in the 21st century. – CuriousOne Apr 02 '16 at 15:30
  • @CuriousOne Thanks for the insight!! I'll try and read Feynman's book if I can find it in the Internet! – Chryron Apr 02 '16 at 16:39

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