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Does quantum theory imply the universe is preordained?

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Re: Does quantum theory imply the universe is preordained?

#81

Post by nwiswell »

munch117 wrote: post #44

Appealing to quantum theory to defend free will does not make sense. If the quantum randomness is fundamental, and reality is stochastic at heart, that makes it non-deterministic, but it doesn't make it any less mechanical. It's in the name, after all: Quantum mechanics . If there is any guiding light to the randomness, any pattern to how the random choices come out, then it's not really random, is it? So, if you thi…

> If there is any guiding light to the randomness, any pattern to how the random choices come out, then it's not really random, is it?

Well, yeah, that's the point. By definition, a deterministic model of reality means there is no room for a free agent to make decisions: things couldn't have worked out another way.

But a mechanism that appears random provides at least the potential for a free agent, since randomness is exactly what it looks like when you cannot predict system outputs purely from system inputs.

It's really a semantic issue. It's not that it's a source of randomness that we're after in order for free will to be possible, but rather non-causality, and quantum mechanics does provide some potential in that regard.

Re: Does quantum theory imply the universe is preordained?

#82

Post by karaterobot »

I have not heard a convincing explanation of how the universe could produce the Monorail episode of The Simpsons merely by a certain configuration of energies in the first moment of the big bang, and the consequences of thereof. The most obvious argument is that the Monorail episode of The Simpsons is not only possible in at least one of the infinitude of quantum, deterministic universes, but inevitable, and that the seeming absurdity is merely my inability to acknowledge my anthropic bias. Nonetheless, I laugh every time I think about the motion of particles leading unavoidably to the invention of everything required for someone to type "I call the big one Bitey!", and for me to appreciate it, or believe—as I must—that I appreciate it. The mind reels!

Re: Does quantum theory imply the universe is preordained?

#83

Post by Xcelerate »

I feel like “deterministic” and “predictable” are often conflated. Suppose I give you the output of encoding a secret message with a one-time pad. Can you predict the message contents without the one-time pad? No. Does that mean the output was generated non-deterministically? No.

More generally, there are strings with Kolmogorov complexity of at least the length of the string but for which the conditional Kolmogorov complexity is very small given some other string.

In this sense, it’s quite possible that quantum mechanics is fully deterministic and there is a hard limit on our ability to predict the future (so for all intents and purposes, quantum mechanics is at some level indistinguishable from true randomness to us despite there being no randomness whatsoever in the laws of physics). In fact, I think the former actually implies the latter:

Consider a completely classical, deterministic universe (or at least imagine a high fidelity molecular dynamics simulation of our lightcone of the universe). Then all of the actions that humans take in an attempt to predict future observations are fully pre-ordained. Why should it be the case that these actions just so happen to lead to output that describes another subsystem’s behavior to arbitrary precision? That would be a strange coincidence to have for whatever set of laws describes the time evolution of this hypothetical universe. Mathematically, how many universes like that are even possible? What sort of bizarre initial conditions would there have to be for this to be the case?

My take is pretty simple: 1) the universe is fully deterministic and 2) quantum mechanics appears inherently random to us because we are inescapably part of the system we are trying to study and predict.

So now the interesting question: is there is an experiment that can distinguish between the case of a fully deterministic universe and one with non-deterministic processes, given that the two would seem to appear the same as far as human observation is concerned?

Re: Does quantum theory imply the universe is preordained?

#84

Post by nyssos »

karmakaze wrote: post #69
nyssos wrote: post #25

Earlier quoted context omitted.

We don't. What we know is that we can't have all of 1. locality (no backwards causation / FTL information transfer) 2. determinism 3. counterfactual definiteness (unperformed measurements still have single definite results: we can talk meaningfully about what we would have seen had we done a different experiment) 4. QM gives correct predictions. Objective-collapse interpretations (like the version of Copenhagen descr…

My bet is on 1. backwards causation. Light takes the shortest path, by (virtually) taking all of them. Similarly all paths to the future are taken and the present must agree with boundary conditions in the future.

> the present must agree with boundary conditions in the future.

This is true but it's not really what's meant by backwards causation here. The specific thing you need is for what happens from times (-ε, ε) to depend on what will happen at times (1-ε, 1+ε) even after conditioning on the intervening times (ε, 1-ε).

Action principles are still local: maximizing the integral of the Lagrangian L(x(t)) over time (by, for instance, taking the shortest path) is equivalent to satisfying dL/dx = d/dt dL/d(dx/dt).

> by (virtually) taking all of them.

This is a superficially appealing analogy but very misleading. Even if you take Feynman diagrams literally, which you shouldn't, the "path" integral runs over field configurations. The classical notion of a particle following some path simply breaks down here.

Re: Does quantum theory imply the universe is preordained?

#85

Post by throwawaymaths »

nyssos wrote: post #50
throwawaymaths wrote: post #48

Earlier quoted context omitted.

Correct me if I'm wrong, but I don't think we even know what "collapse" is. Maybe a better way to say it is that arguments about what is collapse are at the root of distinguishing interpretations

Collapse is when you go from a generic quantum state to an eigenstate of a given measurement operator. The disagreement is about whether this is an objective feature of reality, an artifact of semiclassical approximation, or not a real physical process at all.

Yeah of course we know what the math is and it corresponds to observation, I just mean we don't know deeply what it is beyond what we've operationally defined it as.

Re: Does quantum theory imply the universe is preordained?

#86

Post by dotsam »

nwiswell wrote: post #81
munch117 wrote: post #44

Appealing to quantum theory to defend free will does not make sense. If the quantum randomness is fundamental, and reality is stochastic at heart, that makes it non-deterministic, but it doesn't make it any less mechanical. It's in the name, after all: Quantum mechanics . If there is any guiding light to the randomness, any pattern to how the random choices come out, then it's not really random, is it? So, if you thi…

> If there is any guiding light to the randomness, any pattern to how the random choices come out, then it's not really random, is it? Well, yeah, that's the point. By definition, a deterministic model of reality means there is no room for a free agent to make decisions: things couldn't have worked out another way. But a mechanism that appears random provides at least the potential for a free agent, since randomness…

I find the idea of computational irreducibility useful for rescuing a type of free will in a fully determined world. Computationally irreducible programs are perfectly deterministic, yet you can't predict the output before you run them, and nor are there any shortcuts to get there before running them for the first time. The program running in our brains for 'free will' can be computationally irreducible in this way. No-one can say with perfect accuracy what we will choose to do in advance, not even us.

For me, this kind of free will is enough, though it is rather deflationary when compared to some kind of godlike non-causal free will. I think that if we search for non-causal free will, we lose any hope of explanation or understanding: presumably if it's non-causal, then anything can happen, for no reason.

Re: Does quantum theory imply the universe is preordained?

#87

Post by thefaux »

broscillator wrote: post #78
moritzwarhier wrote: post #72

Earlier quoted context omitted.

Very well put! > I don't necessarily see science as trivial pursuit because of our human limitations Me neither, quite the opposite, but the problem you are describing has always been a problem when discussing metaphysics, as it is commonly called. Science is aware of its limitations, that's what makes it science. But sometimes, people tend to conflate a materialistic world view (maybe even strong determinism) with b…

> But sometimes, people tend to conflate a materialistic world view (maybe even strong determinism) with believing in the scientific method. I would say more than sometimes. It seems that if you're not like that, you're immediately labeled religious.

Religious is also a modern pejorative. It's pretty silly the way it's used given that extreme atheism is just as dogmatic as so called religious faith.

Re: Does quantum theory imply the universe is preordained?

#88

Post by pmontra »

broscillator wrote: post #76
MrGinkgo wrote: post #61

Not sure if this is just a moot point, but I'll say it because I'm genuinely curious to hear what people have to say. Anytime I hear theories like this, I feel wary of accepting it as an air-tight reliable outlook because of human limitations. Like, our understanding of quantum physics and all natural laws come from what we can percieve and measure, but there's bound to be phenomena which we can't percieve or measure…

I think you're just describing human nature. We can look back and see how incomplete theories about the world led to horrible acts, or to averting our eyes from those acts because we thought it was justified, or because we thought there was no better way, or out of fear. Yet there's the prevalent sense of "this time we're getting it right".

People did horrible acts because they did want to do those acts to those other people. They picked a theory to justify them.

Re: Does quantum theory imply the universe is preordained?

#89

Post by twiceaday »

karaterobot wrote: post #82

I have not heard a convincing explanation of how the universe could produce the Monorail episode of The Simpsons merely by a certain configuration of energies in the first moment of the big bang, and the consequences of thereof. The most obvious argument is that the Monorail episode of The Simpsons is not only possible in at least one of the infinitude of quantum, deterministic universes, but inevitable, and that the…

The three body problem is impossible to solve analytically. The state space is clearly all connected but in a way that cannot be short-cut. You have to walk it deterministically one state at a time. Once you reach some interesting state, you know that you will always reach it from your initial state. It is inevitable but in general impossible to predict. There is no simple story to tell as to why you'd end up there, you just do as a culmination of the state-path up to that state. We've reached a state where that Simpsons episode was created. It's very interesting and was impossible to predict from all the way back during the bing bang. Maybe it was inevitable?

Re: Does quantum theory imply the universe is preordained?

#90

Post by numinos1 »

coderenegade wrote: post #77
Filligree wrote: post #42

Earlier quoted context omitted.

Many-Worlds? Or does that fall under #2 for you?

Many worlds is really just another form of determinism. If everything that can happen does, no one in any of the individual universes has free will.

Unless awareness is independent of the universe and traverses the branching worlds through observation and free will.
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