1

I know that the Englert-Greenberger-Yasin (D^2+v^2=1 for a laser) duality relation is often considered an equation quantifying Wave-Particle Duality. However, when I was playing around with the equation I found that it could be derived from a classical perspective. For example, if the slits in a double slit experiment are not of the same width then the probability of finding the photon at a slit can be found from the slit widths. Furthermore, since the amplitude of the light passing through the slits is related to the width of the slits one can find the maximum and minimum intensities of the interference pattern in terms of the slit widths. Adding the squares of the probability and visibility then gives you the EDY duality relation equation. So, since the EGY relation can be derived from a classical perspective, is it really quantum after all?

Clement Decker
  • 383
  • That's more of a pseudo-science interpretation than it is physics. Wave-particle duality does not exist and quanta are not taking classical paths. One can, of course, quantify the dependence of the formation of interference fringes on the intermediate measurement coupling strength, but none of that gets us back to a failed physical picture except in the minds of those who can't let go of an eighty year old bad idea. – CuriousOne Dec 23 '15 at 00:20
  • Your comment is a bit confusing. Wave-particle duality is an essential nature of not only light but all matter. How can you say that wave-particle duality does not exist, in any apparatus? – Clement Decker Dec 23 '15 at 04:20
  • Because wave particle duality is an 80 year old scientific concept that was popular for some time while there was confusion about the foundations of quantum mechanics. That confusion is long over, but for some reason that is hard to understand some people keep holding on to it. There is absolutely no reason to keep perpetuating concepts that didn't work well back then and that still don't work. You can do quantum mechanics perfectly rationally without any confusion and without using this term even once. Things that are not necessary have no place in science. – CuriousOne Dec 23 '15 at 04:49
  • So you are saying that wave-particle duality is an incorrect theory, or at least that it is no longer accepted by the scientific community? You would have to give me evidence because there is still a lot of literature being published on the concept of wave particle duality and I can find no evidence that it is a disregarded theory. – Clement Decker Dec 23 '15 at 05:00
  • Wave particle duality isn't a theory, at all. It's just an unnecessary concept that makes QM much harder to understand than it has to be. That some people are still publishing "intellectual nonsense" is not an argument in favor of it. If you apply a rational concept of what science is and does, then wave particle duality is simply not needed. You can't calculate anything with it in the first place and Feynman and others have developed a very well understood QFT framework in the late 1940s that gives an easy to understand interpretation of ordinary QM that has no conceptual problems. – CuriousOne Dec 23 '15 at 05:05
  • Can you give me a link showing that wave particle duality is not longer in use – Clement Decker Dec 23 '15 at 05:23
  • I can do better: I can cite Feynman's 1948 article "Space-Time Approach to Non-Relativistic Quantum Mechanics", R. P. Feynman Rev. Mod. Phys. 20, 367 – Published 1 April 1948. Start there and then take an introductory class on quantum field theory and read an easy textbook on particle physics. Then re-visit non-relativistic quantum theory and you will notice how useless all the assumptions about waves and particles are. They don't work well for radiation of 2eV and they are completely nonsensical for radiation of 1MeV and above. – CuriousOne Dec 23 '15 at 05:33
  • Hi Clement. Particles like photons are quanta of a quantum field. These can behave like waves in some circumstances and behave like particles in other circumstances, but they aren't a particle or a wave. This is why CuriousOne says wave-particle duality is obsolete. See for example this answer of mine or search this site for more on the subject. – John Rennie Dec 23 '15 at 12:23
  • 1
    But wave particle duality says nothing of the sort. It states very plainly that all matter can exhibit both particle and wave properties. – Clement Decker Dec 23 '15 at 16:53
  • @CuriousOne What do you mean that photons are not taking classical paths – Clement Decker Dec 23 '15 at 18:20
  • I mean that you are implicitly (and falsely) applying the excluded middle law by talking about particles and waves, as if there couldn't be something completely different in nature, as well. Quantum mechanics is that: it's NEITHER particles nor waves. It's its own thing. One can derive particle-like behavior in one corner-case and wave-like behavior in another, but that's not particle-wave duality. Photons in QFT are the same class of "thing" that a p-state is in atomic physics. Does a p-state take a path when it decays into an s-state? – CuriousOne Dec 23 '15 at 19:01
  • @CuriousOne But that has nothing to do with photons taking a certain path. By the way, do you agree with John Rennie's assessment of your position? – Clement Decker Dec 25 '15 at 00:52
  • It has everything to do with photons not being particles that are not taking paths. That's simply an old and 100% incorrect interpretation of non-relativistic quantum mechanics. It seemed to make sense for a few years around the 1920s until it did not make sense any longer because we had found better ways of describing nature in the 1940s. Yes, John Rennie is correct. Photons, which are what you measure as initial and final states of a quantum field can behave like either, but they are neither. At the end of the day it's just a matter of not trying to pound a square peg into a round hole. – CuriousOne Dec 25 '15 at 03:48

0 Answers0