Let me start off with a reference: http://www.lithoguru.com/scientist/lithobasics.html This is an article about the field of lithography and microlithography. Before anyone dismisses the importance of this technology , let me point out that it is used to make EVERY integrated circuit and EVERY circuit board that is used in EVERY computer used worldwide. It is a fundamental optical - chemistry technology of the computer age. Now let me post SEM (scanning electron micrograph) of patterned photoresist material , called photoresist. Photoresist is a very general term for a whole class of polymers, but it means a polymer that is light sensitive. The light exposure restructures the polymer and allows it to either be dissolved in a solvent or become non-soluble in a solvent. The resolution of photoresist is on the order of 1-10 nanometers. I won't go into the process of integrated microcircuit fabrication, my question has to do with the ridges that appear on the sidewalls of the photoresist material. This effect is well known to those who work in the field. The effect is very pronounced when the substrate is metallic, a strong reflector of light. It has been determined (general consensus) that this pattern is caused by the exposure of the photoresist by the standing waves (constructive and destructive addition of the E field) of light used to expose the photosensitive polymer ( photoresist ). Classical optics, based on EM field theory, is used to describe this effect. In fact, the problem is easily solved by coating the substrate with an absorbing material, so there is no reflection. If you read the referenced paper, that layer is called BARC ( Bottom Anti-Reflection Coating). Now while seems like a very simple optics issue, I, personally are very disturbed by it. Let me explain why and then whoever reads this can comment on my thinking. In classical E-M theory one will obtain these standing waves when they solve for the EM fields at the boundary of a conducting plane or surface. The solution is obtained by assuming that the EM fields go to zero at the boundary. But if you think about this approach, then one is defining the entire system and boundary conditions at time = zero. That's a little troublesome. In the experimental setup that is used to expose the photoresist, There is an incoherent ( sodium vapor lamp) or coherent (exicmer laser) light source. When an excited atom releases a photon at time = 0, it does not know how far the optical path will be (that includes air and the lenses in the system). These systems are very complex with lenses consisting of tens of elements and different atmospheres ( some resists work better with no oxygen present and others with no water in the atmosphere). And in the incoherent system, the light source is usually a mercury vapor source and the atoms are emitting photons at random times. So how does one explain the observed phenomena in either classical optics or quantum optics. As was mentioned before, in classical optics the "solution" is arrived at by setting of the boundary conditions at time = 0, but in classical optics we know that the EM wave has to travel a finite distance, when the exposure takes places. The concept of using t=0 and deriving a steady state solution is troubling, when the experiment is not conducted that way. In a quantum mechanical view, single photons are released randomly in time. We seem to understand a lot about photons, but, at least to me, there are some big gapping holes in our fundamental understanding. Photons are bosons, with spin 1 , they also given a frequency and wavelength, which is dependent on their energy. In the optical and near ultraviolet regions, the wave lengths are between 0.25 to 0.80 microns, which is about 10^3 times larger than the atom that releases them. The above photograph is based upon a mercury source. And the ridge spacing clearly corresponds with an interference pattern of the wavelength. Now if I am not mistaken, photons do not interact with each other, so that seems to imply that each photon has to create its own interference pattern for energy absorption within the photoresist material and that energy is very puzzling. Is it absorbed at a single chemical bond and breaks it, or is it absorbed within a range of the photoresist and then causes one bond to break, since it cannot break many bonds. The point I am trying to get at is that there is a lot that we do not understand (maybe just me) about light and how it behaves. We have based our models on macroscopic results of experiements. When I think about the subtle points as mentioned above, I realize that there is a lot we may not understand. Ror example - Is this simple exposure pattern that we see consistent with entanglement?