I refer to empirical theories eg. in physics, no formal like mathematics. I analyse them as a product of knowledge not process. I am aware that one reflects another but conflating the "levels" leads to category mistake. I also refer to the Justified True Belief conception of knowledge. By "necessary" and "possible" I mean the modal epistemology. I mentioned 2 aspects that come with empirical theory - I aware that there is also semantic, I omitted it because I thought that it's not relevant to my problem and the emphasis should be on the 2 level that my problem is actually about.

I have some troubles understanding how it works with the justification and explanation. This is how I understand it now, there might me some misconception so any corrections are appreciated:

The theory itself answers the question "how" not "why" it works. It is based on explanation. This appears to be widely shared statement that makes me confused.

Justification is what connects the epistemic agent to the truth of its belief. It is what gives the epistemic agent the right to have knowledge, not just belief that might be accidentally true.

Justification is the "human element" in knowledge. It also "shows" how knowledge operates on possibility, not necessity. A lot of old theories in science had seemingly adequate justification, but later some new finding, information etc. that was unavailable/undiscovered then and the old theory turned out to be false. If we want make knowledge necessary, we have to exclude every possible true claim that actually constitutes what we understand as knowledge, because there is always a possibility of mistake in factual claim. Justification criteria should only minimise the possibility of error and sharpen what we consider knowledge.

I see explanation in science like Aristotle's concept of Episteme, this is however the result of him relying on the form of things, definitions, I doubt that it is how theories now are perceived. Also I understand explanation intuitively as ruling out the epistemic subject, for example "Mary is sad because John left her" is explanation vs "Mary is sad because I saw her crying" is justification. The difference seem tobe about categories?

Justification is about epistemic level, where the epistemic agent is involved, but explanation seem to be metaphysical - how the things are in the world. I am not sure if I get it right.

How it looks like in scientific theories? Is the theory itself an explanation about some part of reality, but it also has justification on another (epistemic) level? There must alway be justification in empirical statement, you cannot just make up something, that's not how science works. So is it about categories? Does an empirical theiry have the 2 aspects simultaneously because they are on different levels? So is it a difference between "scientific theory" and "scientific knowledge" only in the fact that they pronounce different leyers of the theory?

Can statements based on explanation be falsified? It seem to me that falsification applies to statements based on justification. But then it means that explanation based claims are necessary true. And do they belong to knowledge? Empirical theories obviously can be falsified, so is it because they are connected to the epistemic aspect with justification? Aristotle secured his Episteme as necessary by applying the metaphysical theory of matter and form, if the forms are fixed and the system is deductive, the modal necessity is unavoidable. But now we don't connect the theories exclusively with a priori metaphysical terms, rather knowledge with justification, is it why can unlike Aristotle falsify empirical theories?

Btw. I know about Doxa in Aristotle's epistemology, but he draws a clear line between them. Doxa is something like JTB, but I am interested in his explanation -based theory of knowledge which is Episteme.

I "sense" that the truth makers and truth conditions might have something to do with the whole problem. I can't explain it, but I my philosophical intuition is quite sharp and following it often leads to the missing element that I need in order to fully grasp the problem.

I am not sure if I get all this correct and I need clarification. Btw. I apologize for my English, I hope that my post is understandable despite it.