What Would Happen If We Set Up the Double Slit Experiment Differently?

[marksesl]

As mentioned, if you start with the idea that the photon is a wave: then interference makes perfect sense. But that same photon is quantized and appears at a single point only, giving it particle-like properties. So there are elements of both.

Your reasoning is circular about the importance of the experiment though. You can see that the behavior is fundamentally different when you cannot determine which of 2 slits the light traverses. Such matches the classical view of light as a wave, and what you make of that is up to you. I appreciate that all of this is "self-evident" to you but that is hardly the case for most. For example, the classical view of light as a wave is strictly ruled out in this experiment:

http://people.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf

Not so obvious.

I appreciate your discussion, but there can be no doubt that light and even a single photon is a wave. Photons, as you know, are produced by the quantum fall of electrons in atoms. It is during that fall that a photon's frequency is determined, imparting the very color the photon will have. All photons have an inherent frequency and wavelength. They are waves, but of discrete energy packets which give a particle quality as well. The assumption I'm making is not that light (photons) are waves, that's a given, but that as waves, photons can travel through both slits at the same time. The experiment is flawed, not because I'm assuming that light is wave, but because it is assuming that light is only discrete particles that cannot go through both slits, and by making that false assumption it is thought the photons can be correctly determined as to which way they actually traveled. But, if they do actually go through both slits, the experiment automatically destroys that "both-way" information because waves at right-angles cannot interfere anyway. The experiment eliminates one of the three possibilities, left, right, or "both." And, in eliminating the "both" option, it indirectly destroys knowledge of left or right as well because if the photons do in fact go through both, then left or right knowledge must be something the experiment just makes appear to happen. I'll read the article you linked to though.

 

[harrylin]

[..] Surely it is the very act of placing the detector that causes decoherence and wave-function collapse. We can only know of what we caused ourselves.

[..] All photons have an inherent frequency and wavelength. They are waves, but of discrete energy packets which give a particle quality as well. [...] The experiment is flawed [..] because it is assuming that light is only discrete particles that cannot go through both slits, and by making that false assumption it is thought the photons can be correctly determined as to which way they actually traveled. [..]

I agree with that - to describe a propagating photon as a particle is just no good. There have been papers explaining the same, for example this recent paper by Hobson: http://ajp.aapt.org/resource/1/ajpias/v81/i3/p211_s1 .
Note that perhaps also not all his interpretations are correct, see my post https://www.physicsforums.com/showthread.php?p=4458704

 

[marksesl]

As mentioned, if you start with the idea that the photon is a wave: then interference makes perfect sense. But that same photon is quantized and appears at a single point only, giving it particle-like properties. So there are elements of both.

Your reasoning is circular about the importance of the experiment though. You can see that the behavior is fundamentally different when you cannot determine which of 2 slits the light traverses. Such matches the classical view of light as a wave, and what you make of that is up to you. I appreciate that all of this is "self-evident" to you but that is hardly the case for most. For example, the classical view of light as a wave is strictly ruled out in this experiment:

http://people.whitman.edu/~beckmk/QM/grangier/Thorn_ajp.pdf

Not so obvious.

The experiment is clamed to be proof that photons exist, and the view of quantum physics is justified. It says light is not "classical" waves. So, Einstein was correct. No big news there; after all he won the Nobel Prized for being correct.

The wave aspect of a photon is contained within the photon (which is what I'm referring to). It is a wave packet. That wave packet is due to the drop of an electron from a higher state to a lower in the atom it is part of. The drop has a distinct beginning and ending place and literally squirts out a photon. Thus light is quantized into photons that have color, frequency, and wavelength. The photon is a wave in and of itself. A photon (wave packet) has an unbounded field that can pass through both slits at the same time. Upon striking something that it can interact with, it decoheres and collapses to a much more distinct place, such as to a point of the surface of any detector, giving the impression it only went through one slit, though it went through both.