final nail in the coffin for me a93

Well, inasmuch as we "know" anything, modern physics definitely posits light as a wave. From your first article:

The scientists shot a stream of electrons close to the nanowire, using them to image the standing wave of light. As the electrons interacted with the confined light on the nanowire, they either sped up or slowed down. Using the ultrafast microscope to image the position where this change in speed occurred, Carbone’s team could now visualize the standing wave, which acts as a fingerprint of the wave-nature of light.

However, the article continues:

While this phenomenon shows the wave-like nature of light, it simultaneously demonstrates its particle aspect as well. As the electrons pass close to the standing wave of light, they “hit” the light’s particles, the photons. As mentioned above, this affects their speed, making them move faster or slower. This change in speed appears as an exchange of energy “packets” (quanta) between electrons and photons. The very occurrence of these energy packets shows that the light on the nanowire behaves as a particle.

This shows that it is the process of measurement that results in the particle notion of light. That is, while the light itself is a continuous wave, when we measure the light, we always get discrete results, and thus interpret these results as measuring "photons" of light. This is the famous Measurement Problem.

Of course, we can get really metaphysical about all this. For example, what does it mean for something to be "real", or, more to the point, "physical"? For example, the electron, also a wave (per modern physics) but measured as a discrete particle with identical properties no matter which electron we measure, has angular momentum. However, numerous experiments performed on the size of an electron show that whatever size it has (if any) is way, way, way too small to have the amount of angular momentum that it does (else it would have to be spinning faster than the speed of light). Thus, we disassociate the angular momentum of an electron from any connection to a physical "spin".

In the end, all we have is mathematics to describe the results of our measurements. What "reality really is", inasmuch as such a thing as "reality" even exists at all, is simply our best guess based on what we think we know at the time. After all, if you look at the history of science, one thing has always been true: what we believed to be "reality" has not only proved to eventually be wrong, but often absurdly wrong, as in, what we previously believed to be "the truth" is nothing even remotely like what we now believe to be "the truth", and it's more than a little arrogant to think that we will ever know. What may well happen, however, is we will "know" as much as we'll ever know, so that will become our understanding of "reality" from there on out. But the machines we make will be able to understand far more than us, but will not be able to explain it to us, as we will be incapable of understanding (like a human trying to explain something to an ant). But the machines will reach their limits, too, ad infinitum.

For now, though, light is probabilistically measured as a particle as described by a deterministic wave function. That should be easy for Don to understand, anyway. 😁

This theory has been abandoned now. Existence of photons is accepted now as a fact.

en.m.wikipedia.org/wiki/Photon#Wave–particle_duality_and_uncertainty_principles

Saying that light is a wave or a flow of particles is a bit of a meaningless statement anyway. We say that it has the properties of either. This is a bit vague, indeed, but being such, it cannot be called terribly wrong…

Well said. For example we quite happily view QE charts where one axis is scaled in wavelength and the other axis is based on photon capture.

Not sure how any of that, to include anything in the Wikipedia article, is at odds with what I've said. For example, interference is incompatible with particular nature. On the other hand, we measure EM energy in discrete quanta (photons), which is at odds with a wave description, but more the domain of the Measurement Problem linked to above.

Well, it's hard to argue with that, so I can't say I disagree! 😁

So it is both, roughly speaking. This is at odds with the sentence I just put in boldface above.

Rather than say light is both wave and particle, I would say that light propagates as a wave and is measured as a particle. However, in the Pilot Wave model, a "guide wave" pushes a particle around, allowing one to say that light is actually a particle. So far as I'm aware, it is consistent with wave collapse upon measurement, but the wave would then necessarily need to be physical (as opposed to a probability amplitude), but not something that could be measured directly -- only measured by the particles it is pushing. Well, at the very least, no more sus than dark matter. 😉

It is not me saying all that, it is the physicists. I just know a bit more about the math models they say are relevant, but they know better when and to what extent they are relevant; or at least they think they do.

Speaking about models, there are several ones I am aware of, and I have used all of them in my research (which is NOT physics):

1. Maxwell equations (linear). They describe light (and EM waves in general) with enough intensity on some medium scale, roughly speaking. Their solutions can be called waves. In their time-dependent formulation, they are hyperbolic, which is a math model of waves. In their stationary formulation, they are of Helmholtz type with a large parameter, still of wave type.

2. Quantum electrodynamics often replaced, incorrectly, by QM, as a model for photons. The main PDE there is the Schrödinger equation. The wave function is not “physical” but certain observables of it are. I do not want to get to or even downplay all possible interpretations of it, here is (my) math view. There is nothing random about it. It is a deterministic wave function. Its modulus squared (normalized) is interpreted as the probability density of “finding” the “particle” at some point. The problem is, there is no particle as a point. We can think of the quantum state as a density (a “cloud”). Nothing exotic so far. We can also take the modulus squared of its FT. This is a density again, of the momentum now. Same story here. The exotic comes from the fact that none of those densities determines the other one - they are both determined by the (complex) wave function. Here is where the analogy with the classical mechanics (for densities) breaks down. We can think of those classical densities as a collection of particles, each one moving according to Newton’s laws (see (3) below) but this does not lead us to QM.

3. The transport model (radiative transport, Boltzmann equation, etc.). We think of photons as point particles each one moving along its own straight line (could be more general) but we allow absorption and scattering from the medium. This explains shot noise easily, for example. No waves here.

4. The relativity model. Photons are just particles moving with speed of light but one can naturally assign energy (frequency, or if you wish, color) to them.

I left nonlinear models out which can be fit in any of those. Nonlinearity is relevant for high density light which we do not experience in photography typically.

However, the HUP (Heisenberg Uncertainty Principle) cannot explain diffraction around a barrier, because there is no finite constraint on the particle's position (e.g. light diffracting on the edge of a wall).

Actually, it's the opposite, is it not? That is, partial reflection is an issue for the particular model of light, not the wave model.

The link above leads to a not so great explanation. Basically, they want to explain one consequence of the model with another one without even mentioning the model. The HUP is an inequality, not an equality, for starters, and applies to the standard deviation of the position and the momentum with respect to the corresponding probability measures. Good, but the function to which you apply this is a wave function solving the Schrödinger equation, which they ignore. The physical meanings of what we call position and momentum are directly related to that equation. It tells us how that state propagates from the slit to the other side of it (and the analysis at the slit is not accurate either). Next, they seem to be concerned with very narrow slits, comparable to the wavelength, which is not what we have in photography.

I though a photon was a fluctuation in the electromagnetic quantum field?
(But don't ask me to explain that).