I’m sufficiently uninformed on how quantum mechanics would interact with determinism that so far I’ve been operating under the assumption that it doesn’t. Maybe someone here can enlighten me? Does the behavior of things-that-behave-quantumly typically affect macro-level events, or is this restricted to when you look at them and record experimental data as a direct causal result of the behavior? Is there some way to prove that quantum events are random, as opposed to caused deterministically by something we just haven’t found? (I’m not sure even in principle how you could prove that something is random. It’d be proving the negative on the existence of causation for a possibly-hidden cause.)
Does the behavior of things-that-behave-quantumly typically affect macro-level events, or is this restricted to when you look at them and record experimental data as a direct causal result of the behavior?
Yes; since many important macroscopic events (e.g. weather, we’re quite sure) are extremely sensitive to initial conditions, two Everett branches that differ only by a single small quantum event can quickly diverge in macroscopic behavior.
Does the behavior of things-that-behave-quantumly typically affect macro-level events...?
Yes. They only appear weird if you look at small enough scales, but classical electrons would not have stable orbits, so without quantum effects there’d be no stable atoms.
Is there some way to prove that quantum events are random, as opposed to caused deterministically by something we just haven’t found?
No, but there is evidence. There is a proof that if they were caused by something unknown but deterministic (or if there even was a classical probability function for certain events) then they would follow Bell’s inequalities. But that appears not to be the case.
But this is where things get really shaky for materialism. If something cannot be explained in X, this means there is something outside X that determines it.
Materialists must hope that in spite of Bell’s inequalities, there is some kind of non-random mechanism that would explain quantum events, regardless of whether it is possible for us to deduce it.
Alicorn asked above:
I’m not sure even in principle how you could prove that something is random.
In principle, you can’t. And one of the foundational (but non-obvious) assumptions of materialism is that nothing is truly random. The non-refutibility of materialism depends upon never being able to demonstrate that something is actually random.
Later edit: I realize that this comment is somewhat of a non-sequitur in the context of this thread. (oops) I’ll explain that these kinds of questions have been my motivation for thinking about Newcomb in the first place. Sometimes I’m worried about whether materialism is self-consistent, sometimes I’m worried about whether dualism is a coherent idea within the context of materialism, and these questions are often conflated in my mind as a single project.
And one of the foundational (but non-obvious) assumptions of materialism is that nothing is truly random.
In that case I am not a materialist. I don’t believe in any entities that materialists don’t believe in, but I do believe that you have to resort to Many Worlds in order to be right and believe in determinism. Questions that amount to asking “which Everett branch are we in” can have nondeterministic answers.
No worries—you can still be a materialist. Many worlds is the materialist solution to the problem of random collapse. (But I think that’s what you just wrote—sorry if I misunderstood something.)
Suppose that a particle has a perfectly undetermined choice to go left or go right. If the particle goes left, a materialist must hold in principle that there is a mechanism that determined the direction, but then they can’t say the direction was undetermined.
Many worlds says that both directions were chosen, and you happen to find yourself in the one where the particle went left. So there is no problem with something outside the system swooping down and making an arbitrary decision.
The EPR paradox (Einstein-Podolsky-Rosen paradox) is a set of experiments that suggest ‘spooky action at a distance’ because particles appear to share information instantaneously, at a distance, long after an interaction between them.
People applying “common sense” would like to argue that there is some way that the information is being shared—some hidden variable that collects and shares the information between them.
Bell’s Inequality only assumes there there is some such hidden variable operating locally* -- with no specifications of any kind on how it works—and deduces correlations between particles sharing information that is in contradiction with experiments.
* that is, mechanically rather than ‘magically’ at a distance
Well, actually everything has to follow them because of Bell’s Theorem.
Edit: The second link should be to this explanation, which is somewhat less funny, but actually explains the experiments that violate the theorem. Sorry that I took so long, but it appeared that the server was down when I first tried to fix it, so I went and did other things for half an hour.
There is no special line where events become macro-level events. It’s not like you get to 10 atoms or a mole and suddenly everything is deterministic again. You’re position right now is subject to indeterminacy. It just happens that you’re big enough that the chances every particle of your body moves together in the same, noticeable direction is very very small (and by very small I mean that I can confidently predict it will never happen).
In principle our best physics tells us that determinism is just false as a metaphysics. Other people have answered the question you meant to ask which is whether the extreme indeterminacies of very small particles can effect the actions of much larger collections of particles.
In principle our best physics tells us that determinism is just false as a metaphysics.
As said above and elsewhere, MWI is perfectly deterministic. It’s just that there is no single fact of the matter as to which outcome you will observe from within it, because there’s not just one time-descendant of you.
Thats a fair point, but I don’t think it is quite that easy. On one formulation a deterministic system is a system whose end conditions are set by the rules of the system and the starting conditions. Under this definition, MWI is deterministic. But often what we mean by determinism is that it is not the case that the world could have been otherwise. For one extension of ‘world’ that is true. But for another extension, the world not only could have been otherwise. It is otherwise. There are also a lot of confusions about our use of indexicals here: what we’re referring to with “I”, “You”, “This”, “That” My” etc. Determinism usually implies that ever true statement (including true statements with indexicals) is necessarily true. But it isn’t obvious to me that many worlds gives us that. Also, a common thought experiment to glean people’s intuitions about determinism is basically to say that we live in a universe where a super computer that can exactly predict the future is possible. MWI doesn’t allow for that.
Perhaps we shouldn’t try to fit our square-pegged physics into the round holes of traditional philosophical concepts. But I take your point.
Why would determinism have anything to say about indexicals? There aren’t any Turing-complete models that forbid indexical uncertainty; you can always copy a program and put the copies in different environments. So I don’t see what use such a concept of “determinism” would have.
Thinking about this it isn’t a concern about indexicals but a concern about reference in general. When we refer to an object we’re not referring to it’s extension throughout all Everett branches but we’re also referring to an object extended in time. So take a sentence like “The table moved from the center of the room to the corner.” If determinism is true we usually think that all sentences like this are necessary truths and sentences like “The table could have stayed in the center” are false. But I’m not sure what the right way to evaluate these sentences is given MWI.
I’m sufficiently uninformed on how quantum mechanics would interact with determinism that so far I’ve been operating under the assumption that it doesn’t. Maybe someone here can enlighten me? Does the behavior of things-that-behave-quantumly typically affect macro-level events, or is this restricted to when you look at them and record experimental data as a direct causal result of the behavior? Is there some way to prove that quantum events are random, as opposed to caused deterministically by something we just haven’t found? (I’m not sure even in principle how you could prove that something is random. It’d be proving the negative on the existence of causation for a possibly-hidden cause.)
Yes; since many important macroscopic events (e.g. weather, we’re quite sure) are extremely sensitive to initial conditions, two Everett branches that differ only by a single small quantum event can quickly diverge in macroscopic behavior.
Yes. They only appear weird if you look at small enough scales, but classical electrons would not have stable orbits, so without quantum effects there’d be no stable atoms.
No, but there is evidence. There is a proof that if they were caused by something unknown but deterministic (or if there even was a classical probability function for certain events) then they would follow Bell’s inequalities. But that appears not to be the case.
But this is where things get really shaky for materialism. If something cannot be explained in X, this means there is something outside X that determines it.
Materialists must hope that in spite of Bell’s inequalities, there is some kind of non-random mechanism that would explain quantum events, regardless of whether it is possible for us to deduce it.
Alicorn asked above:
In principle, you can’t. And one of the foundational (but non-obvious) assumptions of materialism is that nothing is truly random. The non-refutibility of materialism depends upon never being able to demonstrate that something is actually random.
Later edit: I realize that this comment is somewhat of a non-sequitur in the context of this thread. (oops) I’ll explain that these kinds of questions have been my motivation for thinking about Newcomb in the first place. Sometimes I’m worried about whether materialism is self-consistent, sometimes I’m worried about whether dualism is a coherent idea within the context of materialism, and these questions are often conflated in my mind as a single project.
In that case I am not a materialist. I don’t believe in any entities that materialists don’t believe in, but I do believe that you have to resort to Many Worlds in order to be right and believe in determinism. Questions that amount to asking “which Everett branch are we in” can have nondeterministic answers.
No worries—you can still be a materialist. Many worlds is the materialist solution to the problem of random collapse. (But I think that’s what you just wrote—sorry if I misunderstood something.)
Suppose that a particle has a perfectly undetermined choice to go left or go right. If the particle goes left, a materialist must hold in principle that there is a mechanism that determined the direction, but then they can’t say the direction was undetermined.
Many worlds says that both directions were chosen, and you happen to find yourself in the one where the particle went left. So there is no problem with something outside the system swooping down and making an arbitrary decision.
Those sorts of question can arise in non-QM contexts too.
Or, of course, the causes could be non-local.
What are Bell’s inequalities, and why do quantumly-behaving things with deterministic causes have to follow them?
Alicorn, if you’re free after dinner tomorrow, I can probably explain this one.
The EPR paradox (Einstein-Podolsky-Rosen paradox) is a set of experiments that suggest ‘spooky action at a distance’ because particles appear to share information instantaneously, at a distance, long after an interaction between them.
People applying “common sense” would like to argue that there is some way that the information is being shared—some hidden variable that collects and shares the information between them.
Bell’s Inequality only assumes there there is some such hidden variable operating locally* -- with no specifications of any kind on how it works—and deduces correlations between particles sharing information that is in contradiction with experiments.
* that is, mechanically rather than ‘magically’ at a distance
Um… am I missing something or did no one link to, ahem:
http://lesswrong.com/lw/q1/bells_theorem_no_epr_reality/
Thank you, although I find this a little too technical to wrap my brain around at the moment.
Well, actually everything has to follow them because of Bell’s Theorem.
Edit: The second link should be to this explanation, which is somewhat less funny, but actually explains the experiments that violate the theorem. Sorry that I took so long, but it appeared that the server was down when I first tried to fix it, so I went and did other things for half an hour.
There’s no good explanation anywhere. :(
There is no special line where events become macro-level events. It’s not like you get to 10 atoms or a mole and suddenly everything is deterministic again. You’re position right now is subject to indeterminacy. It just happens that you’re big enough that the chances every particle of your body moves together in the same, noticeable direction is very very small (and by very small I mean that I can confidently predict it will never happen).
In principle our best physics tells us that determinism is just false as a metaphysics. Other people have answered the question you meant to ask which is whether the extreme indeterminacies of very small particles can effect the actions of much larger collections of particles.
IAWYC except, of course, for this:
As said above and elsewhere, MWI is perfectly deterministic. It’s just that there is no single fact of the matter as to which outcome you will observe from within it, because there’s not just one time-descendant of you.
Thats a fair point, but I don’t think it is quite that easy. On one formulation a deterministic system is a system whose end conditions are set by the rules of the system and the starting conditions. Under this definition, MWI is deterministic. But often what we mean by determinism is that it is not the case that the world could have been otherwise. For one extension of ‘world’ that is true. But for another extension, the world not only could have been otherwise. It is otherwise. There are also a lot of confusions about our use of indexicals here: what we’re referring to with “I”, “You”, “This”, “That” My” etc. Determinism usually implies that ever true statement (including true statements with indexicals) is necessarily true. But it isn’t obvious to me that many worlds gives us that. Also, a common thought experiment to glean people’s intuitions about determinism is basically to say that we live in a universe where a super computer that can exactly predict the future is possible. MWI doesn’t allow for that.
Perhaps we shouldn’t try to fit our square-pegged physics into the round holes of traditional philosophical concepts. But I take your point.
Why would determinism have anything to say about indexicals? There aren’t any Turing-complete models that forbid indexical uncertainty; you can always copy a program and put the copies in different environments. So I don’t see what use such a concept of “determinism” would have.
Thinking about this it isn’t a concern about indexicals but a concern about reference in general. When we refer to an object we’re not referring to it’s extension throughout all Everett branches but we’re also referring to an object extended in time. So take a sentence like “The table moved from the center of the room to the corner.” If determinism is true we usually think that all sentences like this are necessary truths and sentences like “The table could have stayed in the center” are false. But I’m not sure what the right way to evaluate these sentences is given MWI.
Voted down because my writing is confusing or because I said something stupid?