Super-computers running a million-million cycles a second take millions of seconds (months) to simulate not what a photon does in a million-millionth of a second, but in a million-millionth of that (Wilczek, 2008), p113. Why does it take so much computing to copy what these tiniest bits of the universe do if they have no internal structure? The answer proposed is that a photon isn’t a tiny particle taking one path but a processing wave spreading over many.
How then does light travel? Feynman’s sum over histories method predicts how light goes from A to B by calculating all possible paths, then choosing the one with the least action integral (Feynman et al., 1977) p26-7. It was accepted as a method that works not a theory that is true because particles can’t do that. Like quantum theory, it was a physical impossibility that just happened to predict perfectly.
However if a photon is a processing wave, Feynman’s method works because it really does take all possible paths, and the first to trigger a physical event is where we see it arrive. Light then doesn’t need to know the fastest path in advance because it can take every path and let the instance that arrives first reincarnate it in a physical event. Its path is then the one the photon took, and the restart removes all the other instances, like a magician removing the evidence of how a trick is done after it happens.
The physical law of least action that has puzzled science for centuries is then explained by a quantum effect. A particle can’t know the fastest path to an unknown destination in advance, but a quantum wave can take every path and choose fastest later, just as Feynmann’s method does.
To recap, knowing nothing in advance, the photon wave spreads down every path, and restarts when it reaches a detector, as a processing wave can. What reaches a detector by the fastest route isn’t a single particle that magically knows where to go in advance, but a quantum ensemble that explores every path and disbands when the job is done.
Generalizing this quantum effect gives the quantum law of all action, that for any set of physical possibilities, quantum entities take them all. Feynman’s method is based on this law, for as he said “everything that can happen does happen” (Cox & Forshaw, 2011). A particle must travel from point A to B by one path, but quantum entities take every possible path simultaneously, all of them, before generating a physical event. The same law underlies Gellman’s quantum totalitarian principle, that everything not forbidden is compulsory, because it must happen sooner or later. The physical law of least action is then explained by the quantum law of all action, which applies because every physical event arises from a myriad of quantum events.
The quantum world explores every option to let us take the best as a physical event and ignore the rest, so if this isn’t the best of all possible worlds, it isn’t for lack of options. That our world isn’t the best it could be is obvious, but it increasingly isn’t a higher power that makes it so but ourselves. When some of us start wars to increase their power, others must defend against them, and everyone suffers. We then could live in the best of all possible worlds if we stopped supporting power-possessed beings.
If the quantum law of all action is universal, it applies to quantum spin as well as how light travels.