This is an attempt at a “heuristic point of view” for quantum physics that treats it as an evolutionary process. I hope it’s clear that I’m not proposing any new theory, but only trying to bring out some implications that are as well-established as anything can be, in this murky field. Please let me know if any of this makes sense to you... but I hope this doesn’t turn into a philosophical debate about the relationship between physics and mathematics. I’m not trying to prove anything one way or the other about that – just using the question to open up what might be a fruitful way of looking at the strange combination of causality and indeterminacy in QM. Before the arrival of QM, the one thing that seemed completely certain in physics was the principle of causality. By that I mean, everything that happens in the world has to happen exactly the way it does, because everything “obeys” precise mathematical equations. This idea of a “deterministic” universe had at least one very basic problem, that I’ll discuss in a moment. But the first point I want to make is that this idea works. All of physics amounts to finding the equations that describe how things happen, and this is still true in QM. Its equations still describe the “causal evolution” of the wave function, even though the wave function itself gives only a probability distribution for the actual results of an observation. Before QM, this notion that things “obey” precise mathematical laws could just be taken for granted. But if we take the evidence of QM at face value – if we accept that at the most basic level interactions don’t “obey” equations, but happen at random – then this opens up a new question. It’s not just a matter of “giving up causality” – because we know that to an extremely good approximation, the world is causally predictable. The question is – where does this causality come from? How and why does a world based on random interaction evolve into something that looks as deterministic as it possibly can? This is not a philosophical question, in my opinion; we’re not going to get the answer from logic or metaphysics. But if we take this seriously as a question for physics, we can find some fairly clear indications in QM about where to look for the answer. First – the very basic problem with determinism in physics is that mathematics is nowhere near powerful enough to run a universe. As I’m sure we all know, the equations for even quite simple hypothetical systems – take three point-masses interacting via Newtonian gravity, in flat Euclidean space – generally have no analytic solution. So we may talk about things “obeying equations” in the real world, but that’s just shorthand for a situation we haven’t really figured out how to describe. The evolution over time of any actual physical system is far more precisely “lawful” than anything we can ever expect from mathematics. In any actual physical situation, there are many different kinds of systems “obeying” several different kinds of “laws” all at once, as they interact with each other. At most, this kind of situation can only be approximated mathematically. So while our equations are obviously important for understanding how physical systems evolve over time, it’s not at all clear that “obeying equations” can be a complete or basic explanation of what’s happening here. Now QM comes along and says, quite clearly – causal evolution according to equations is only part of the story. At bottom, the “laws” represented in the equations are a complex set of stochastic “guidelines” within which systems “choose” at random how to behave. More precisely, the equations of QM represent the set of possibilities available to a system at a given time. The system evolves by interacting with other systems in such a way that a choice gets made and communicated between the systems (i.e. in a “measurement”), so that the choice then creates a new set of possibilities available to each system. What I want to suggest is that the word “evolution” in this context means something closely related to “evolution” in the biological sense. In both cases we are dealing with situations that are both highly controlled and open to random input. And in biology, we have a clear idea of where the complicated controlling structures come from, because we understand how the whole process has evolved. If you look at the molecular mechanics that goes on all the time in living cells, you see an extremely complex and quite chaotic system based on random interaction, that nonetheless manages with amazing reliability all the operations involved in sustaining and reproducing the organism. This seems very similar to the way physical systems manage to behave in amazingly “lawful” ways, even though the base-level processes are essentially random. In physics, the nature of the evolutionary process is not well understood, to say the least. But we have a lot of evidence for it, in QM, so we know a lot about how it works... and we know what it has ultimately accomplished – namely, causality. Each quantum interaction is a selection (measurement) that determines certain information and passes that on to other such events. That is, each event narrows down and makes more specific the range of possibilities for what can happen in the future. This happens in many different ways that define many different kinds of physical information. But the long-term result of the process is that the possibilities for what can happen next, in any given situation, get narrowed down as much as they can be... given the base-level indeterminacy on which the whole business operates. In other words, there’s an evolving selection process that continues until – except at the very basic level – randomness is nearly eliminated, and everything that happens looks like it has to happen just that way. It comes to appear as though the outcome of any physical situation is completely predictable, even though in nearly all cases the situation is too complex for an actual prediction to be computed mathematically – even when our equations are correct. That’s because what’s basically going on in physical interaction is not computation. It’s random selection within a complex set of evolved constraints. Therefore the behavior of physical systems can be “causally determined” at a much higher level of complexity than we can imitate in mathematics.