Between you and viole, I am faced with a crash course review of physics just to understand the points you are making, let alone, even begin to address them if that is possible.
Brain research entered the modern era with the
EEG, and has really accelerated since the 1990s when
new brain-scan tools and methods became available. The constant question is, how does it work? Which leads to further questions ─
what is a neuron? What part of the brain does what? , and how do its groups of neurons interact with each other and other groups? And, of course, how come?
So with free will, by what process does the brain perceive questions and decide them? Here's
an article on decision-making. But since it all boils down to the stimulation of neurons, and their complex interactions to derive a collective response, we're looking at decision-making as complex interacting chains of biochemical and bioelectrical cause+effect in the brain.
And those chains will be determined in-house ie by the brain's own procedures, unless something external intervenes ─ a blow to the head, the effect of a drug, infection, and so on, can displace in part the orderly procedures of the brain, though the result will still be derived by chains of cause+effect, just different ones. (That effect isn't limited to decision-making, of course.)
The only alternative to cause+effect in physics is quantum randomness.
This is the best short article I can find in a rapid search,
Such events may or may not be able to interfere with quantum randomness with chains of cause+effect in brains. As far as I'm aware, we don't presently know whether that happens, or whether, if it happens, it can produce significant variations to what would otherwise result. But because randomness is the only alternative to cause+effect, it gets mentioned.
I recall watching a program hosted by the physicist Brian Greene where he discussed our perception of physical reality and how our perception is a function of electromagnetism viewed on the human scale. I cannot go into detail for reasons I have already stated regarding my trivial understanding of the concepts, but I get the impression that the responses I am getting relate in some way to Greene's descriptions.
I don't know the program. He may have been discussing the role of bioelectricity in the communication between neurons, or in the brain generally (eg the waves the EEG picks up). But that's just a guess.
