The problem is created by the degenerate tendency to reduce multiplicity (particulars) to singularity (one universal.)
For example, color and wave-length are two different objects neither of which can be reduced to the other for that would confuse, which is to say eliminate distinction between, the two. On the other hand, that does not mean there is no relation between the two. We know, for example, that there is a strong type of correlation between the two that we refer to as causation. We know that when wave-length changes that the color changes too.
There is nothing mysterious regarding qualia. What there is is an illusion of mystery created by the inability to comprehend that categories are man-made and that whether we are going to categorize some object of experience as physical or qualitative does not make that object any more or less mysterious.
The so-called “physical realm” is quite simply a category that includes some objects of experience and excludes others. In its most abstract from, it includes only formulas, viewing physical sensations as merely “subjective” (in other words, it puts them in a category that is called “subjective realm”.)
Someone may ask “if it doesn’t belong to physical realm then where does it belong?” And to be able to answer that question one would have to enumerate every known category and make sure that each one is sufficiently defined so that we can unambiguously determine whether any given object of experience belongs to it or not. Then, we would simply compare our non-physical object against the requirements of every category and note where it belongs, if it belongs anywhere. And what if it belongs nowhere? Then we would simply categorize it as “uncategorized”. Simple.
So, yes, qualitative objects such as color, smell, taste, etc do not belong to or exist in physical realm. No matter how deep you look into a physical brain or perform calculations in order to predict its behavior, you will never experience any colors, tastes, smells, etc. So where do they belong or exist? They belong to or exist in . . . qualitative realm. Realm being nothing but a fancy word for category, class, set and other container objects.
“Oh my god, that’s so deep!”
Yeah, it is deep as hell.
Qualitative objects such as color can have their physical correlates such as wavelength.
No need to confuse the two.
Everyone is happy.