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I recently stumbled upon this episode of the future of life institute podcast on "the nature of reality" and keep coming back to thinking about it. I am still not sure whether to take this whole thing as basically trivial or whether I should go into full blown believe crisis mode. Now that I am thinking about it I already have a full blown believe crisis (maybe insight ornanating would be a better description?). In contrast to my regular believe crisis, while I definitely feel like this view should in some sense change how I think about the world/base reality there is another part that is just really reluctant to accept yet another complication in how I think about the world. I just can't manage to find anything in particular that is different from this view compared to my previous view, except when I apply it to topics like consciousness or the nature of computation that make me really confused anyways. If you are reading this none of this is probably really "new". It is just like someone is spelling out this view that I've sometimes seen people gesture at, but he is more explicit about it.
Quantum mechanics does say that there are particles in a sense, like you can say that there are particles but particles aren’t really the thing. You can ask questions of reality that entail that reality is made of particles and you will get answers that look like answers about particles. But you can also ask questions about the same physical system about how it is as a wave and you will get answers about how it is as a wave. And in general in quantum mechanics, there are all sorts of questions that you can ask and you will get answers about the physical system in the terms that you asked those questions about. So as long as it is a sort of well-defined physical experiment that you can do and that you can translate into a kind of mathematical form, what does it mean to do that experiment? Quantum mechanics gives you a way to compute predictions for how that experiment will turn out without really taking a particular view on what that physical system is, is it a particle? Is it a wave? Or is it something else? And I think this is important to note, it’s not just that quantum mechanics says that things are particles and waves at the same time, it’s that they’re all sorts of things at the same time.
So you can ask how much of my phone is an elephant in quantum mechanics. A phone is totally not the same thing as an elephant, but a phone has a wave function, so if I knew the wave function of the phone and I knew a procedure for asking, “Is something an elephant?”, then I could apply that procedure to the phone and the answer would not be, “No, the phone is definitely not an elephant.” The answer would be, “The phone is a tiny, tiny, tiny, tiny, tiny bit an elephant.” So this is very exaggerated because we’re talking phones and elephants, all these numbers are so tiny. But the point is that I can interrogate reality in quantum mechanics in many different ways. I can formulate whatever questions I want and it will give me answers in terms of those questions.
I had been already familiar with the idea that quantum mechanics adds a probabilistic element to your whole world model, that there is basically that whole class of things that are "possible" like a baseball suddenly being in front of you, but the probability being essentially so small that it does not matter (not to mention that quantum effects of your own perception/brain totally dominating the equation: Most worlds where there is suddenly a baseball moving without anything before happening, there is some "classical" mechanic explanation and even when we get to the quantum, explanations, most of those would at least in the baseball example be misfirings in my brain (both because of the great mass of a baseball and the specificness of a baseball, that would probably be better explained by some misfiring in my brain (since otherwise where are all the indistinguishable blobs?))). What was new to me was to basically put the limits of what you are actually able to observe on some kind of pedestal as the only thing that really matters in some sense.
You can say in Newtonian mechanics or classical physics, there’s something arguably reasonable about saying, “Here is the system, it’s these particles and they’re moving around in this way.” And that’s saying something. I think you can argue about whether that’s actually true, that that’s saying something. But you can talk about the particles themselves in a fairly meaningful way without talking about the observer or the person who’s measuring it or something like that. Whereas in quantum mechanics, it’s really fairly useless to talk about the wave function of something without talking about the way that you measure things or the basis that you operate it on and so on. [...] So this is a conception of reality that’s kind of like a big game of 20 questions. Every time we look out at reality, we’re just asking different questions of it. Normally we’re narrowing down the possibility space of how reality is by asking those questions, getting answers to it. To me a really interesting question is like, what is the ontological reality status of all those big sets of questions that we’re asking? Your tendency as a theoretical physicist is to say, “Oh, the wave function is the thing that’s real and that’s what actually exists, and all these extra things are just extra things that we made up and our globbed onto the wave function.” But I think that’s kind of a very impoverished view of reality, not just impoverished, but completely useless and empty of any utility or meaning because quantum mechanics by its nature requires both parts. The questions and the state. If you cut out all the questions, you’re just left with this very empty thing that has no applicability or meaning.
It also reminded me of Scott Garrabrant’s perspective on inference with finite factored sets. I am not sure I really understood that either though.