We can argue about physical limitations of reality, but all we ever really understand is a model of reality. Sometimes it seems to match predictions well. But it’s always the model we understand. Given how complex reality appears to be and how comparatively simple our models appear to be, it seems likely that the models are incomplete, and probably always will be incomplete.
As such, perhaps it would be better to say that given your understanding of the physiology of the optics of the eye, and the receptors and nerves of the eye, that you believe strongly that it’s not possible to detect the difference between 4k and 8k at some common viewing distance. Or perhaps more simply “most” or “nearly all” people can not detect the difference. As with unusual occurrences like tetrachromats, it could be that there are some people with higher resolution perception such that they could see the difference.
I don’t have a reference now, but I recall from a Feynman writing that there have been experiments to see how few photons a person could perceive. As I understand it, nobody was able to say they saw the photon (or bundle of a few photons), but they were asked to press a button whenever they thought they might have seen a photon. The distribution came back slightly biased towards affirmation that they could see the single or few photons, rather than the distribution mere chance would predict. Nobody could tell you what that photon looked like, and yet somehow they did perceive it x% of the time, where x was something like 10% (or the experiment had a flaw that cued the subject—I don’t know if it’s been repeated).
Now, I’m not suggesting this says anything at all about resolution, it’s about intensity, but it is still it is interesting. And the idea of the study is worth considering for learning about resolution perception.
Perhaps nobody would pass the Pepsi challenge comparing an 8k Mona Lisa to a 4K Mona Lisa at some distance. But if subjects were shown a series of many images and asked to push a button when they would thought it was 8k, maybe would tell us something interesting.
There are lots of things to control for, like a correlation among all the 8k images or 4k images, but I think it could be done. I don’t really know the details of how the hypotheses are constructed for a good study, but if someone has some suggested reading, I’m interested. Perhaps we would say:
* All subjects are shown the same N images
* The image is randomly (normal? uniform?) selected to be the 8k version or 4k version.
* If a version of the image has been shown to the subject, it will not be shown again to that subject in either resolution
* Subjects that have seen the images can not discuss with subjects that have not
And million other thing like the coloring of the images, subject matter, and so on. Maybe have a version that provides feedback on correctness.