interpretations for QM

[gib65]

I found these interpretations of QM from http://www.quantumconsciousness.org/overview.html. Would the QM experts at SFN say these are pretty accurate?

 

Persisting is the Copenhagen interpretation (measurement or conscious observation collapses the wave function) which is consistent with "positivist" philosophies in which the mind constructs reality. The Copenhagen view puts consciousness outside physics, but doesn't account for fundamental reality; it merely accounts for the results of experiments.

 

The "multiple worlds" or "multiple minds" view follows a suggestion put forth by Hugh Everett that each superposition is amplified, leading to branching off of a new universe and conscious observer; in one universe the cat is dead, and in another universe the cat is alive. There is neither collapse nor reduction, however an infinity of realities (or of conscious minds) is required.

 

Another interpretation which avoids reduction/collapse is that of David Bohm in which objects have both a particle aspect and a "pilot" wave aspect (non-local hidden variable or quantum potential) which acts on and guides the particle. Bohm's approach shows that the quantum world can exist independently of the human mind, offering a "realist" alternative to Bohr's prevailing "positivist" Copenhagen view. But Bohm's view requires another layer of reality.

 

The theory of decoherence reconciles the Copenhagen interpretation with quantum superpositions in the absence of measurement or conscious observation. Any interaction, or loss of isolation, of a quantum superposition with a classical system (e.g. through heat, direct interaction or information exchange) would "decohere" the quantum system to classical states. But decoherence theory doesn't define isolation (no quantum system is truly isolated from its classical surroundings) nor deal with superpositions which are isolated.

 

Finally, several proposals posit an objective threshold for reduction ("objective reduction", "OR"). British mathematical physicist Sir Roger Penrose suggests that each superposition corresponds with bifurcation/separation of the universe at its most basic level (quantum gravity, or fundamental spacetime geometry at the Planck scale). This is akin to the multiple worlds view, however according to Penrose the separations of the universe at its most fundamental level are unstable and spontaneously reduce ("self-collapse") due to an objective, intrinsic feature of spacetime geometry ("objective reduction"). Moreover the larger the superposition, the more rapidly it reduces. For example an isolated electron in superposition would undergo objective reduction only after 10 million years; a one kilogram cat in superposition would self-collapse in only 10-37 seconds. Penrose's proposal is currently being tested experimentally.

[Severian]

Yes, they seem fairly reasonable. Most of them (especially the first two) are not really science though, since they can't be tested.

[gib65]

Thanks Severian. I want to devote this thread to a discussion of each interpretation for my own personal curiosity (but everyone's welcome, of course ).

 

First of all, the Copenhagen interpretation says "conscious observation collapses the wave function". Does this mean to say that only conscious observation collapses the wave function? It seems to be saying that if no conscious beings existed, all material bodies would exist in superposition states of infinite magnitude. So the Sun would not only be at the center of our solar system, but everywhere in the universe, as would every other star, planet, particle, galaxy, etc.

 

What does that say about human consciousness? The quote above says "the mind constructs reality" but it would have to construct a reality whose underlying rules and structure (i.e. the laws of classical mechanics) are pre-calculated and determined. A good example is the kind of work I do - I'm a computer programmer. Whenever I find a bug, it can rattle my brain. I can scan the program for hours not knowing where the bug lies, not seeing the flaw. But then I suddenly find it, and it all makes sense. Now if my mind was making up reality, I would have had to have known there was a bug on some unconscious level beforehand. Otherwise, the only thing determining reality would be my conscious mind, and as far as that part of me is concerned, the program is supposed to work. What this means, however, is that the unconscious part of my mind which keeps track of all the classical laws and makes sure that we never really observe violations of them, would have to be keeping track of an enormous amount of information. It would have to remember the state of each and every bit in my computer, for if only one of them was off, the program should crash. The same argument could be made for physicists when they conduct experiments or work with technology built upon the nature of physics as they understand it.

 

What does the Copenhagen interpretation have to say about this?

[gib65]

Why does nobody care about the topics I'm passionate about? * sigh *

[Severian]

First of all, the Copenhagen interpretation says "conscious observation collapses the wave function". Does this mean to say that only conscious observation collapses the wave function?

 

The problem with this, that makes the question unanswerable on a scientific level, is that it is not something we can ever test. We cannot ever make an observation without "conscious observation" (since we are conscious entities).

 

The only way around this is to introduce some other property of a state that collapses the wavefunction. For example, several people have suggested that it is the size or complexity of an object that collapses the wavefunction. So we collapse the wavefunction because we are made up of lots and lots of particles. This also has problems: what size is the relevant size and who decides; by what mechanism does this work.

 

I think we could speculate on this forever... and probably will.

[gib65]

Thanks for replying, severian.

 

I guess that's why the Copenhagen interpretations remains the only feasible scientific interpretations. All the others are trying to appeal to a non-observable ontology.

 

Anyway, I'll continue to ask other questions in the slight hope that others (or yourself) might want to take stabs at them. If not - oh well - I guess I'll just let this thread die

 

About the "multiple worlds" interpretation: it seems to get rid of the need for collapse or superposition states, but there is still some randomness that's left unexplained. Why do we end up perceiving this universe? Presumably, if our minds are multiplied as many times as the universe itself is, there must be a random "collapse" of who we turn out to be - that is, which one of the many copies of ourselves we experience ourselves to actually be in the end (but I guess each other copy is asking the same question ).

[bascule]

Persisting is the Copenhagen interpretation (measurement or conscious observation collapses the wave function) which is consistent with "positivist" philosophies in which the mind constructs reality.

 

That's certainly a misleading statement:

 

- Positivists can be materialists. They don't have to be monists

- Materialism is also consistent with the Copenhagen Interpretation

 

The Copenhagen view puts consciousness outside physics

 

Wrong.

 

Consciousness remains outside physics, but that has nothing to do with the Copenhagen interpretation. It has to do with the inability of science to directly observe consciousness. But that's pretty much relegated to entirely different branches of science than physics (e.g. neurophysiology, cognitive science), although some (monists) would like to argue that science will never observe consciousness.

 

There's this enormous misconception that consciousness and waveform collapse are somehow intertwined, and that idea is being used (by the likes of the site you linked) to argue for quantum mind

 

The real answer is what Severian said: we collapse the wavefunction because we are made up of lots and lots of particles.

[gib65]

There's this enormous misconception that consciousness and waveform collapse are somehow intertwined, and that idea is being used (by the likes of the site you linked) to argue for quantum mind

 

In more ways that one. The Copenhagen interpretation seems to say that observation collapses the waveform whereas proponents of quantum consciousness suggest that the waveform collapse causes consciousness when it occurs in microtubules inside our neurons.

[Amr Morsi]

Regards,

 

What is now mainly adopted with science and scientists is the Compenhagen Interpretations (Born Interpretations). The matter of relation between reality and observation, although being a vital issue, is not the main difference between various trends. It is the meaning of the wave function, mainly the squared modulus of the wave function.

 

A serious trend now in the field of science, is adopting another interpretation, as previously mentioned in that thread. It is related to probability meaning of QM, and QFT. Not a few facts supports the new interpretation, which coincides with Schrodinger's Proposition: That it is the average effect of not-precisely known fundamental facts. You can refer to Schrodinger's Papers about that. I am just introducing a fact. Thanks for accepting it friendly.

[gib65]

What about that pilot wave theory? That surely was disproven, wasn't it? To my understanding, a pilot wave would constitute a local hidden variable which I thought was disproven by Bell.

[Wormwood]

The problem with this, that makes the question unanswerable on a scientific level, is that it is not something we can ever test. We cannot ever make an observation without "conscious observation" (since we are conscious entities).

 

The only way around this is to introduce some other property of a state that collapses the wavefunction. For example, several people have suggested that it is the size or complexity of an object that collapses the wavefunction. So we collapse the wavefunction because we are made up of lots and lots of particles. This also has problems: what size is the relevant size and who decides; by what mechanism does this work.

 

It probably has nothing to do with size as even electronic measuring devices will suffice as consciousness to collapse a wave function. Also, it was actually observable evidence that led to this belief that consciousness is needed to collapse a wave function in this first place. Check out the double slit experiment:

http://www.princeton.edu/~pear/pdfs/Double-Slit.pdf

(or see if you can find something about the original double slit from the 60's, the site above just shows that intention doesn't effect the experiment)

 

It isn't that consciousness is constructing reality so much as consciousness allows reality to be validated as real. It's like movement; movement can only be validated as movement when it is in relation to something else. So the mind doesn't have to know the outcome to cause the event, it simply has to be present to cause one set event (which is usually the reasonable or expected outcome) to occur.

 

I know it is sort of divergent, but this universal need for consciousness sort of explains the necessity of the anthropic principle. That a given universe will always work toward conscious life because consciousness is needed to make it exist seems like a reasonable proposition given the realm of discussion.

[fredrik]

Gib, I didn't respond to your threads because I think it's concepts difficult enough to ponder on your own, and even more difficult to discuss with others as there is no common terminology and my experiences from long time ago is that the discussions easily turn into some kind of trashing where all effort is spent on trying to understand the meaning of words and concepts with minimal progress made. That doesn't mean I think it's not interesting.

 

I think back in high school I read an book called the "quantum self", it started out interesting and fun but then got very fuzzy... so I think I never finished it. But no matter what I think about it (I don't remember much anyway) perhaps it could be of your interest. I read (half) this book back before I had studie QM formalism so I never read it in the light of my current improved state and I doubt I would consider it worth the time now since I'm onto other projects I rate more promising.

 

/Fredrik

[Amr Morsi]

I think logic is all the time true, but true logic. When we speak about physics then we must compare with known (or trusted) facts and logics that have to do with physics.

 

The main thing that is not accepted by some scientists in Copenhagen's Interpretation is that it cannot determine the result of one experiment (with knowing the initial conditions of the experiment). It is only speaking about probabilities without any certainty (WHICH INCLUDES HUP) in any result.

[gib65]

Anybody have any thoughts on this quote:

 

The theory of decoherence reconciles the Copenhagen interpretation with quantum superpositions in the absence of measurement or conscious observation. Any interaction, or loss of isolation, of a quantum superposition with a classical system (e.g. through heat, direct interaction or information exchange) would "decohere" the quantum system to classical states. But decoherence theory doesn't define isolation (no quantum system is truly isolated from its classical surroundings) nor deal with superpositions which are isolated.

 

What would be the conditions defining "isolation" and "interaction"?

 

I started another thread here that makes clear that "decoherence" never really means collapsing the wavefunction to a perfectly "classical" state (i.e. Newtonian/Maxwellian state). Decoherence always results in an approximation to a classical state - it's a matter of how fine tuned your measurements are (think HUP). If this is the case then maybe a quantum system is always decohering to a smaller or greater degree with its environment, and the degree of uncertainty involved is a function of the idiosynchratic constraints the environment puts on it. Under some conditions, a particles position will be rather localized (such as when an electron is in a low-level orbital around a nucleus), whereas in other conditions, it may be much more spread out (such as when an electron is free roaming in a vastly empty space).

 

Does this make sense? Is this consistent with current mainstream theory?

[foodchain]

Anybody have any thoughts on this quote:

 

 

 

What would be the conditions defining "isolation" and "interaction"?

 

I started another thread here that makes clear that "decoherence" never really means collapsing the wavefunction to a perfectly "classical" state (i.e. Newtonian/Maxwellian state). Decoherence always results in an approximation to a classical state - it's a matter of how fine tuned your measurements are (think HUP). If this is the case then maybe a quantum system is always decohering to a smaller or greater degree with its environment, and the degree of uncertainty involved is a function of the idiosynchratic constraints the environment puts on it. Under some conditions, a particles position will be rather localized (such as when an electron is in a low-level orbital around a nucleus), whereas in other conditions, it may be much more spread out (such as when an electron is free roaming in a vastly empty space).

 

Does this make sense? Is this consistent with current mainstream theory?

 

 

I like to think of what happens to atoms in a BEC experiment at this point. I mean really if I understand what you are talking about well enough, then I don’t know how you would study anything quantum at that point. I mean atoms have energy levels and happen to be active really, it seems at absolute zero or a billionth of a degree away from such that quantum structure or atomic structure seems to fail, so the system, in this case an atom will always have some energy to it, I don’t know if an atom just left alone somewhere in space light-years away from anything else would bec, it seems the universe at this point just is not that cold though, luckily, its a scary though that such could be the case someday though. I wish they could study at a direct way though what happens to gluons during a BEC.

[gib65]

I haven't followed through with this thread in a while, but I'd like to pick it up again. I'm researching the Many-World Interpretation, and I've got a question.

 

For those of you who might not be familiar with Everett's work (the founder of the Many-Worlds Interpretation, or the "Correlation Interpretation" as he initially called it), here is a snippet from wikipedia:

 

Everett's Ph.D. work provided such an alternative interpretation. Everett noted that for a composite system (for example that formed by a particle interacting with a measuring apparatus' date=' or more generally by a subject (the "observer") observing an object (the "observed" system) the statement that a subsystem (i.e. the observer or the observed) has a well-defined state is meaningless -- in modern parlance the subsystem states have become entangled -- we can only specify the state of one subsystem relative to the state of the other subsystem, i.e. the state of the observer and the observed are correlated. This led Everett to derive from the unitary, deterministic dynamics alone (i.e. without assuming wavefunction collapse) the notion of a relativity of states of one subsystem relative to another

[/quote']

 

So my question is this: It is said that the Many-Worlds Interpretation is unlike other interpretations of QM in that it is deterministic. I don't follow that. Even if the observer is correlated with the measurement he makes, there is no accounting for how that correlation was established. Why should his observations be correlated with the specific measurement he made? It seems just as random as the "collapse" of the Copenhagen Interpretation.

[BenTheMan]

It is said that the Many-Worlds Interpretation is unlike other interpretations of QM in that it is deterministic.

 

I don't follow that either. I think that that's the point---no one can tell what state a specific electron will be in before an experiment is done. To say that the many worlds interpretaiton is deterministic is akin to saying that you know WHICH universe (of the many) that you are living in.

 

It seems just as random as the "collapse" of the Copenhagen Interpretation.

 

I think that I agree. Where did you read that it was deterministic?

[gib65]

I don't follow that either. I think that that's the point---no one can tell what state a specific electron will be in before an experiment is done. To say that the many worlds interpretaiton is deterministic is akin to saying that you know WHICH universe (of the many) that you are living in.

 

 

 

I think that I agree. Where did you read that it was deterministic?

 

The wikipedia article (I know, not that great of a source). It says:

 

MWI allows quantum mechanics to become a realist' date=' deterministic, local theory making it more akin to classical physics (including the theory of relativity).

[/quote']

 

What about this decoherence view, that its a matter of interactions with the environment? The way the wikipedia article puts it is that a quantum system will decohere when it somehow "interacts" (not clearly defined) with something in its environment, leaving a portion of the waveform to collapse into a more classical state, and the rest to dissipate into the environment.

 

Is the state in which it decoheres still considered random? And what does it mean for the wave to "dissipate" into the environment?