Quantum Mechanics

[shunyadragon]

OK, so if I'm reading you right, it is the natural laws that are causes, not events or objects?

I believe at the micro world Quantum level this is the case.

 

[Yokefellow]

Adam and Eve were the first Conscious Observers to collapse the Wave Function.

We call that event 'The Big Bang'.

Participatory anthropic principle.

 

[osgart]

I hear some scientists claim there is no cause and effect at the micro level. Only patterns and laws. I would rather think that the laws are causes. Isnt that creeping into non physical reality to say that though?

 

[shunyadragon]

I hear some scientists claim there is no cause and effect at the micro level. Only patterns and laws. I would rather think that the laws are causes. Isnt that creeping into non physical reality to say that though?

No,Natural Laws are an intimate part of our physical reality. Even though they are not physical themselves there is no evidence that they are part of any other reality than our own physical existence.

Patterns? Needs more explanation. Any observed patterns would be effects and a product of Natural Laws.

 

[Bob the Unbeliever]

Adam and Eve were the first Conscious Observers to collapse the Wave Function.

We call that event 'The Big Bang'.

Participatory anthropic principle.

Indeed. And shortly after that? Cain, then Able. And Seth too. Lots of Big Bangs, apparently...

 

[shunyadragon]

Indeed. And shortly after that? Cain, then Able. And Seth too. Lots of Big Bangs, apparently...

BANG! Bang! Bang! Bangity bang bang!

 

[Brickjectivity]

At that level...at a higher (?more gravitationally consequential) level things are strongly deterministic. To think otherwise is to abandon common sense and practical thinking.

That sounds reasonable. Small sized events in the past can make big changes though its unlikely.

Seems to me, if the position of the electron (for example) after wave function collapse is non-deterministic (random), there is no such thing as strict causality.

I think in the model it is random, but it may not be random. Observing quantum particles equals interacting with them, so for all studious purposes they appear to have unpredictable behavior.

Superposition means particles exist in multiple states at once, but it does not prove that the pattern of collapse is uncaused. How do quantum computers work, then? After all a wave function does not collapse without an observation which implies cause. To me then while it must be modeled as random a collapse must be connected to other events.

 

[Polymath257]

That sounds reasonable. Small sized events in the past can make big changes though its unlikely.

I think in the model it is random, but it may not be random. Observing quantum particles equals interacting with them, so for all studious purposes they appear to have unpredictable behavior.

Superposition means particles exist in multiple states at once, but it does not prove that the pattern of collapse is uncaused. How do quantum computers work, then? After all a wave function does not collapse without an observation which implies cause. To me then while it must be modeled as random a collapse must be connected to other events.

it isn't the collapse itself that is 'uncaused', but the specific (eigen)-value for the observable after the collapse.

 

[shunyadragon]

That sounds reasonable. Small sized events in the past can make big changes though its unlikely.

In the macro world small sized events result in a variation of outcomes based on a fractal pattern, and do not make big changes in and of themselves.

I think in the model it is random, but it may not be random. Observing quantum particles equals interacting with them, so for all studious purposes they appear to have unpredictable behavior.

The model is not random because the outcome is predictable and has a predictable pattern. Yes, the events appear random, but the processes are not.

Superposition means particles exist in multiple states at once, but it does not prove that the pattern of collapse is uncaused.

I believe from the human experimental perspective they appear in multiple states at once. The pattern of collapse is predicable and likely is determined by underlying natural laws.

How do quantum computers work, then? After all a wave function does not collapse without an observation which implies cause. To me then while it must be modeled as random a collapse must be connected to other events.

Quantum computers would function on the predictable pattern of Quantum events, and not based on the predictability of individual events nor human observations which are limited.

 

[Brickjectivity]

it isn't the collapse itself that is 'uncaused', but the specific (eigen)-value for the observable after the collapse.

There is a leap from 'Random model' to uncaused. QM has undone Newton's clockwork universe, but with Uncertainty absolute randomness seems like a leap. Would this not require overcoming the Uncertainty Prjnciple? What looks random may just be immeasurable, and what about string theory? Maybe fermions and bosons aren't the smallest particles which also potentially undermines your claim that the eigenvector is uncaused.

 

[Polymath257]

There is a leap from 'Random model' to uncaused. QM has undone Newton's clockwork universe, but with Uncertainty absolute randomness seems like a leap. Would this not require overcoming the Uncertainty Prjnciple? What looks random may just be immeasurable, and what about string theory? Maybe fermions and bosons aren't the smallest particles which also potentially undermines your claim that the eigenvector is uncaused.

Perhaps the issue is what, exactly, the word 'random' means. It. isn't clear to me how randomness requires the negation of the UC.

It looks like, in essence, you are suggesting the existence of 'hidden variables' that produce the observed effects in a causal way. This possibility is specifically eliminated by Aspect's experiment showing Bell's inequalities are violated. Now, at this point, that only eliminates causality in a very limited situation, but QM deals with many other situations in an essentially equivalent way. Furthermore, the EPR paradox (which Aspect's experiment tested) was specifically proposed as a challenge to the randomness inherent in QM.

String theory is a quantum field theory and has the same sort of uncaused events as ordinary quantum theory. The stringy nature of fundamental particles doesn't change the relevance of Bell's inequalities and their violation. If anything, it underlies that QM is not a causal theory.

 

[exchemist]

Perhaps the issue is what, exactly, the word 'random' means. It. isn't clear to me how randomness requires the negation of the UC.

It looks like, in essence, you are suggesting the existence of 'hidden variables' that produce the observed effects in a causal way. This possibility is specifically eliminated by Aspect's experiment showing Bell's inequalities are violated. Now, at this point, that only eliminates causality in a very limited situation, but QM deals with many other situations in an essentially equivalent way. Furthermore, the EPR paradox (which Aspect's experiment tested) was specifically proposed as a challenge to the randomness inherent in QM.

String theory is a quantum field theory and has the same sort of uncaused events as ordinary quantum theory. The stringy nature of fundamental particles doesn't change the relevance of Bell's inequalities and their violation. If anything, it underlies that QM is not a causal theory.

I suppose one might object to the use of "random" when 95% of measured values lie within a tiny envelope the width of h/4π.

 

[tayla]

I think in the model it is random, but it may not be random. Observing quantum particles equals interacting with them, so for all studious purposes they appear to have unpredictable behavior.

Superposition means particles exist in multiple states at once, but it does not prove that the pattern of collapse is uncaused. How do quantum computers work, then? After all a wave function does not collapse without an observation which implies cause. To me then while it must be modeled as random a collapse must be connected to other events.

Yes, very insightful comments.

I doubt that observation or measurement triggers wavefunction collapse.

Perhaps the location of the electron (for example) after wavefunction collapse is random because it is "spinning" through its various states and it collapses at a random time? I think you are hinting at something like this.

 

[LegionOnomaMoi]

One question is how our classical ideas of causality have to be modified in light of the discoveries of quantum theory. In particular, the fact that initial conditions do NOT determine later states means that the classical concept of causality needs at least some massage.

I think an important lesson that is usually missed in discussions such as these is that in a very real sense quantum mechanics is actually a very simple form of classical mechanics and is if anything more deterministic. In classical mechanics, an absolutely fundamental assumption built into the entire framework is that of isolation: the deterministic equations/dynamics of classical systems hold only for systems that do not interact with their environment or other systems not under consideration (and are not influenced by forces which we consider unimportant enough to ignore). In other words, the laws governing classical systems which render them deterministic only hold for systems which cannot and do not exist- ever.
Of course, it would have been reasonable for someone like Laplace to suppose that the deterministic structure of classical mechanics was an accurate and true description of physical systems more generally. Sure, there were built in contradictions, but it was not unreasonable to suppose that later developments would tell us how to incorporate ourselves into the physical theories we developed rather than rely on ourselves as external observers capable of freely choosing initial conditions such that we could generalize from them.
And that is in essence what quantum theory did: force us to confront how we had assumed that we were free to generalize from particular physical situations to create the deterministic classical theories we did, and then used the results to assert that we weren't free.
Quantum theory is essentially (and I mean that in the "in its essence" sense) classical- right up until we confront the fact that we can no longer consider ourselves external to the systems we treat as isolated even though they are not.
The deterministic nature of quantum theory breaks down right where the assumptions built into classical theories fail: observation. We cannot consider the determination of initial conditions to be wholly distinct from us nor the system to be isolated.
Initial conditions are set or chosen by observers, and classical systems are measured, tested, etc., by observers. But there is no place for observers capable of doing either in classical physics. Quantum theory just forced us to come to terms with this.

 

[LegionOnomaMoi]

I agree, but it remains uncertain as to how the Laws of Thermodynamics apply within the Quantum world.

It remains uncertain as to how the laws of thermodynamics apply within any world. Despite some textbook assertions and presentations, thermodynamics doesn't reduce to statistical mechanics, and even if it did statistical mechanics itself is built upon increasingly shaky assumptions that don't stand up to much scrutiny if they are to be more than an extremely useful framework for dealing with a variety of physical situations (and quantum statistical mechanics, unlike classical statistical mechanics, is built up not from attempts at first principles from its non-statistical counterpart but rather by analogy with statistical mechanics itself).

 

[shunyadragon]

It remains uncertain as to how the laws of thermodynamics apply within any world. Despite some textbook assertions and presentations, thermodynamics doesn't reduce to statistical mechanics, and even if it did statistical mechanics itself is built upon increasingly shaky assumptions that don't stand up to much scrutiny if they are to be more than an extremely useful framework for dealing with a variety of physical situations (and quantum statistical mechanics, unlike classical statistical mechanics, is built up not from attempts at first principles from its non-statistical counterpart but rather by analogy with statistical mechanics itself).

I agree to a certain extent. The Laws of Thermodynamics are practical applications to the macro world, and not considered theoretically absolute laws any more, I do not consider them even practical nor useful for applications to the Quantum World.

 

[Polymath257]

I think an important lesson that is usually missed in discussions such as these is that in a very real sense quantum mechanics is actually a very simple form of classical mechanics and is if anything more deterministic. In classical mechanics, an absolutely fundamental assumption built into the entire framework is that of isolation: the deterministic equations/dynamics of classical systems hold only for systems that do not interact with their environment or other systems not under consideration (and are not influenced by forces which we consider unimportant enough to ignore). In other words, the laws governing classical systems which render them deterministic only hold for systems which cannot and do not exist- ever.
Of course, it would have been reasonable for someone like Laplace to suppose that the deterministic structure of classical mechanics was an accurate and true description of physical systems more generally. Sure, there were built in contradictions, but it was not unreasonable to suppose that later developments would tell us how to incorporate ourselves into the physical theories we developed rather than rely on ourselves as external observers capable of freely choosing initial conditions such that we could generalize from them.
And that is in essence what quantum theory did: force us to confront how we had assumed that we were free to generalize from particular physical situations to create the deterministic classical theories we did, and then used the results to assert that we weren't free.
Quantum theory is essentially (and I mean that in the "in its essence" sense) classical- right up until we confront the fact that we can no longer consider ourselves external to the systems we treat as isolated even though they are not.
The deterministic nature of quantum theory breaks down right where the assumptions built into classical theories fail: observation. We cannot consider the determination of initial conditions to be wholly distinct from us nor the system to be isolated.
Initial conditions are set or chosen by observers, and classical systems are measured, tested, etc., by observers. But there is no place for observers capable of doing either in classical physics. Quantum theory just forced us to come to terms with this.

The Schrodinger is a deterministic wave equation. But, because the wave function only determines probabilities and not specifics, it is strange to call QM a deterministic theory. The 'collapse' of a wave function has NOTHING to do with consciousness, but *everything* to do with the interaction of a complex environment. We may be part of that complex environment, but the collapse happens either way.

 

[LegionOnomaMoi]

I started writing a number of responses to many posts on this thread and these became far too numerous and far too lengthy. I still intend to post these responses, but I am including a small number of references I have scanned or linked to that are worth reading in general but which relate particularly to issues in this thread and still more particularly contain many points I would like to be able to refer to and expand on/explain rather and let readers choose whether or not they feel like they require a deeper basis or wider context to understand the points I will be touching on. The chapter on the failure of classical determinism is from a must-read on the subject of determinism in general by Earman, and I am including one volume simply because it is freely available (and relevant) and references much I may refer to (both topics and texts). I decided to keep to only a few choices and thus had to sadly exclude some papers/chapters I would really have liked to, but oh well. So see the link below for the free ebook and see attached:
Physical (A)Causality Determinism, Randomness and Uncaused Events

 

[LegionOnomaMoi]

The Schrodinger is a deterministic wave equation. But, because the wave function only determines probabilities and not specifics, it is strange to call QM a deterministic theory. The 'collapse' of a wave function has NOTHING to do with consciousness, but *everything* to do with the interaction of a complex environment. We may be part of that complex environment, but the collapse happens either way.

Consciousness isn't the issue. I'm not arguing for quantum mind or anything like that. There are those who have, including those who built the theory. But
1) The wave function fails utterly for all but elementary quantum mechanics and tends to be the topic of discussion because one hopes it can somehow capture much more with greater simplicity. This isn't the case. But it doesn't really matter because the point is that the "collapse" of the wave function is a form of entanglement. It is a fundamental failure at the most basic level of the only shred of determinism that existed in classical physics: namely that if we ignore all the philosophical/metaphysical issues (see previous thread with the attached chapter on the failures of determinism in classical physics) and the fact that we are assuming that we can speak in ideal situations of isolated systems that are epistemically indeterministic because all possible measurements yield a subset of rational numbers while trajectories, space, time, and in general the structure of classical dynamics require the continuum (and since the rationals have measure 0, the probability that we can ever even measure something accurately is 0) s.t. when we consider even the 3-body problem we have to assume that the arbitrary departures from precise initial conditions that deviate far more than we can measure must exist, then we are still left with the key assumption:
In classical physics, systems are deterministic because we are free to choose/set/prepare initial conditions of systems that we treat as isolated by ignoring effects we aren't interested in or for simplicity and because without the isolation criteria we lose even the classical laws of mechanics (and classical physics more generally), particularly conservation laws, and then just to top it off we have to assume that somehow we can interact with an isolated system to measure/observe it but that somehow this is an interaction with an isolated system (a contradiction in terms).
Fine. The problem is that nothing in classical physics says that even granting all these assumptions and a slew of others, we have any empirical, theoretical, or mathematical reason for generalizing this deterministic nature of isolated systems to all systems. Quite the contrary: we can't generalize from empirical/experimental conditions without the freedom to assume that we could have e.g., chosen different initial conditions, different samples of particular elements, different times or places for experiments, or even the ability to determine what can be taken as negligible to render classical physics (or the natural sciences!) possible.
2) Quantum mechanics shows clearly that not only does this extrapolation from the determinism of isolated systems to all systems fail utterly and that we can't be free to generalize from the particular in the manner required in all of empirical science whilst simultaneously asserting determinism holds true in general, but far more: it forces us to realize clearly how deep the assumption that we can freely make choices is to all empirical science, esp. via Bell's theorem/inequality:
"The condition that the choice of the experiments is taken to be a free one means that the experimentalist must be thought to be able to choose them at will, without being unconsciously forced to one or the other choice by some hidden determinism. This condition has an important role in the proof of the theorem. It is often left implicit because of its apparent obviousness. Here it is explicitly stated. But let it be observed that, when all is said and done, it appears as constituting the very condition of the possibility of any empirical science.”
(emphasis added, p. 64)
d'Espagnat, B. (2006). On Physics and Philosophy. Princeton University Press
(See also the chapters by Primas attached to the last post)

 

[shunyadragon]

The above reference is ok, but in general scientists DO NOT extend the principle of Determinism to the micro world and scale of Quantum Mechanics. Determinism only has practical application to the macro world, and remains a predicable and applicable concept for Methodological Naturalism in the macro world.

Bell's Theorem simply proposes this limitation.

From: bell's inequality theorem - Google Search
"In its simplest form, Bell's theorem states: No physical theory of local hidden variables can ever reproduce all of the predictions of quantum mechanics."