Please comment if you're gonna down vote so i can improve :)
I have poured over a lot of resources in the past few hours but have been unable to reach a satisfying answer, this question is more about underlying (quantum?) mechanics than a simple explanation. I will link everything at the end.
In a youtube video, the presenter mentioned that specular reflection occurs in metals because electrons bounce the 'wave' back by resonating with it [1:18]. It is mentioned that this type of reflection requires a flat surface, the required flatness depending on the wavelength of the light. He then mentions the Arecibo telescope and how the same principal is used to reflect microwaves there and in microwave ovens.
All of that makes intuitive sense to me, I am familiar (to a computer engineering graduate level) with EM fields, the EM spectrum, wavelengths, and other basics such as that. What does not so much make sense is the mechanism which allows visible light to pass through that mesh, but reflects microwaves, if I am modeling it as specular reflection. In other words, what about the size of these holes/imperfections in relation to wave LENGTH causes them to act as a 'flat' surface and allow the oven to reflect the waves (specularly, with resonating electrons, assuming the video is correct)?
Some of my research has lead me to believe that it would not be specular reflection occurring, but more properties of standing waves in EM fields and that a faraday cage is an entirely separate mechanism of shielding.
This post leads me to believe it has more to do with the faraday cage type effect, which (please correct me if I am wrong) would be because of charges flowing back towards the 'emission' point and creating a positive and negative part of the microwave ovens shell? In particular, he mentions that
It is well established that to block a transmission of a particular frequency, size of the largest hole in the Faraday cage must be AT MOST 1/2 the wavelength of the frequency of the undesired transmission.
However I am shakey on why this is well established, IE why there would be able to be holes (imperfections in the flatness, tying it back to the youtube video) of the size of half the wavelength. I also have a faint understanding of the attenuating effects of this method of shielding (to my understanding, the microwaves do not stop, but drop off in power dramatically within insignificant distance of the mesh), although that does not help my confusion.
This similar post got me closer I believe, but I am looking for an understanding more than a mathematical proof, and the top reply somewhat lost me at
Well, if you want to discuss waves of wavelength λ only, their dependence on space must always have the form A⋅cos(2πx/λ): waves with the right distance between the minima. However, the metallic cage surrounding the interior of the oven imposes the potential ϕ=0 at a very dense network of points. When you try to write down the potential as A⋅cos(2πx/λ), while making sure that it's zero at all points where there is a conductor, you will find out that there is no solution except for A=0. The wave of the given wavelength just can't get through at all. Alternatively, you could calculate the reflection from the metallic points of the mesh (not counting the holes). They would interfere with each other and guarantee that the probability of reflection is nearly 100 percent.
and so on. From that post, I am visualizing it in terms of 3D standing waves, where the higher frequencies/smaller wavelengths would lead to more 'discrete sections' of potential in the EM field which could leak though, as visible light does, somewhat like shown below:
Lastly, I came across this reddit post which makes me feel as though it is some combination of my standing wave view and the interpretation of photons as particles of a certain influence size.
The problem with that is you are mixing up classical and quantum views of physics. The wave isn't some particle oscillating along which can make it through the holes. What is actually happening is the wave is merely representing a disturbance in the electrical field, and the mesh is a conductor in which is generated an opposing electromagnetic field. This results in reflection as the holes are too small for the disturbance to penetrate.
I realize this is already quite long so I will not give any more of my thoughts until I see if I am on the right track or need to reimagine how I interpret some of these models, thank you to anyone with the time and expertise to reply!
[Previously linked resources not linked]
If photons move linearly, what's actually stopping them from passing through a microwave oven mesh?
Why does wavelength decide the size/diameter of these holes in the microwave door?
