This is a somewhat serious physics hypothesis based on philosophical problems that have been bugging me for the last two years. A physics hypothesis out of somebody with science education, but scarcely a year's worth of college-level knowledge in physics.

The meat of this, if it were going to become a paper, is really the problem of unifying special and general relativity with determinism.
Special relativity doesn't seem like such a problem, because all the equations you get in basic textbooks are always standing on some specific point which can observe other things moving in time according to its own perception of time even if movement distorts it. But general relativity isn't like that. The point of general relativity is basically that the reference frames get smaller, and anything that happens in the universe could happen starting anywhere without happening according to the perception of time on any other planet or roadside or atom or anything. Again it might seem like "what's the big deal?".
But the big deal is that almost every physics equation assumes that there is such a thing as time evolution. There seems to be a really fundamental assumption since Newton that everything that happens in the universe is similar to a thrown ball arcing through the air, where you can add in a time axis and it doesn't conflict with anything else happening on the surrounding earth. But looking at the above (imperfect?) description of general relativity, you can already see how that violates the concept of being able to start at any position in the universe and having no special position for observing events. Doesn't general relativity suggest that every proton can be its own "observer"? Can a quark be an observer? We know a gauge boson can't stop and be an observer because then it would be difficult to describe causality, but if we exclude those and only pick slower, more massive things, where does it end?
Today my best guess was that it ended approximately at quarks. Quarks were the smallest observers, approximately, and they would observe gluon exchange binding them into a proton which would occur in time. The reason the three quarks point in different yet unknown color directions (entanglement of color charge) is basically that everything is happening at once; the three quarks are all having an equally valid reference frame and exchanging gluons from one reference frame to another, all sort of rotating around interchangeably because their constant balanced interactions have made them equally important to the history dimension and thus approximately interchangeable.
Here is what I think: physicists might be oversimplifying things by not separating these three reference frames into different timelines that then combine.

Caveat #1: I don't yet know how this explains gravity, or what it means for gravity. I simply haven't gone there yet.
Caveat #2: I could absolutely be wrong.

In some ways, people are not quite predictable, and they seem to be in a superposition of three different things they might do. But is that really any different from quarks? You don't know whether a quark is pointing red, green, or blue, it could be any of them.

In other ways, people seem to associate into groups around particular ideologies relatively naturally, and start all moving at once like one object. Religion. People getting pushed away from one race category and into another one through the process of forming populations. People sorting together around the same experiences of gender, and settling onto their accurate gender, and possibly forming a movement. Not all of it is reducible simply to "cultural traditions", "cultural compatibility". What if people cluster into a more highly-specific, constructed identity like "Trotskyist" or "Gramscian"? It's like there's something actively gluing people together that keeps them from merging into the same Marxism. Something which also might be operating in some of the supposedly "cultural" cases.

I think that being able to show that time itself is physically the merging of separate timelines that are bent off course from the way they would individually go into a history they all produce at once would go a long way toward making historical materialism hard to deny any more