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Fyzix
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I think it's time for the annual quantum interpretation poll.
Vote for which interpretation you currently think represents reality.
Vote for which interpretation you currently think represents reality.
Fyzix said:I think it's time for the annual quantum interpretation poll.
Vote for which interpretation you currently think represents reality.
Fyzix said:Just search of quantum interpretations, there seems to have been like 20 of them, but I decided to call this annual so it can be the offical one of 2011 and not be moved to the philosophy section.
It is not Copenhagen, else it would not have its own name.Fyzix said:Yeah I forgot consistent histories, but isn't it just copenhagen really?
There is collapse and it's indeterministic.
I have my own interpretation.Fyzix said:Specify details for other here in the thread.
unusualname said:That "thermal interpretation" sounds cool ;-)
just a quick (maybe annoying) question, is QM linear in the thermal interpretation?
tom.stoer said:I don't really understand the difference between "Many Worlds (With splitting of worlds)" and "Everettian MWI (Decoherence)".
A. Neumaier said:Of course. Everything valid in standard quantum mechanics and quantum field theory remains valid in the thermal interpretation. In particular, the Schroedinger equation holds without any modification.
The Schroedinger equation i hbar psidot = H psi is valid universally in (conservative) quantum mechanics. This includes the relativistic case and quantum field theory, where H is the generator of time translations of the Poincare group.unusualname said:i assume you mean the Schrödinger Evolution eqn, which is a postulate of QM (maybe unfairly named), not the non-relativistic Schrödinger eqn, which has limited applicability.
You are welcome!unusualname said:Hmm, I like the overall philosophy, might be worth studying the book in more detail
A. Neumaier said:The Schroedinger equation i hbar psidot = H psi is valid universally in (conservative) quantum mechanics. This includes the relativistic case and quantum field theory, where H is the generator of time translations of the Poincare group.
You are welcome!
I think it is due do the fact that (because of renormalization issues) books on relativistic QFT don't talk about time evolution but only about the S-matrix. The whole formalism looks so different from QM that it seems to be a completely different subject.unusualname said:Yes, some people don't realize that the Schrödinger Evolution equation is valid universally even in qft, this is due to undergraduate introductions to QM where everyone learns the non-relativistic equation with Schrödinger's name, the evolution law should perhaps be called the Heisenberg-Schrödinger eqn.
tom.stoer said:I don't really understand the difference between "Many Worlds (With splitting of worlds)" and "Everettian MWI (Decoherence)".
In case we have two classical scenarios (e.g. Schrödinger's cat, coin tossing, ...) decoherence explains why we always observe one of these two classical scenarios instead of a quantum superposition. But decoherence does NOT explain why we observe exactly THIS scenario. It explains why the cat is either dead or alive. But if there IS a dead cat it does NOT explain why the cat dead, not alive.
There is another ingredient required, e.g. MWI with random splitting of worlds.
Am I wrong?
A. Neumaier said:I think it is due do the fact that (because of renormalization issues) books on relativistic QFT don't talk about time evolution but only about the S-matrix. The whole formalism looks so different from QM that it seems to be a completely different subject.
See https://www.physicsforums.com/showthread.php?t=476412 for a discussion of this.
Dmitry67 said:2 for Copenhagen?
Who?
unusualname said:Can you learn the friggin forum etiqutette and post links to abstracts you silly person
A. Neumaier said:I am not silly, and resent being labelled as such. Unless you apologize, this was my last response to a posting by you.
A. Neumaier said:Could you please list the few most recent of these?
It is not Copenhagen, else it would not have its own name.
I have my own interpretation.
I call it the the thermal interpretation since it agrees with how one does measurements in thermodynamics (the macroscopic part of QM (derived via statistical mechanics), and therefore explains naturally the classical properties of our quantum world. It is outlined in my slides at http://arnold-neumaier.at/ms/optslides.pdf and the entry ''Foundations independent of measurements'' of Chapter A4 of my theoretical physics FAQ at http://arnold-neumaier.at/physfaq/physics-faq.html#found0 . It is described in detail in Chapter 7 of my book ''Classical and Quantum Mechanics via Lie algebras'' at http://lanl.arxiv.org/abs/0810.1019 . See also the following PF posts:
https://www.physicsforums.com/showthread.php?p=3187039&highlight=thermal#post3187039
https://www.physicsforums.com/showthread.php?p=3193747&highlight=thermal#post3193747
The thermal interpretation
It is superior to any I found in the literature, since it
-- acknowledges that there is only one world,
-- is observer-independent and hence free from subjective elements,
-- satisfies the principles of locality and Poincare invariance, as defined in relativistic quantum field theory,
-- is by design compatible with the classical ontology of ordinary thermodynamics
-- has no split between classical and quantum mechanics,
-- applies both to single quantum objects (like a quantum dot, the sun or the universe) and to statistical ensembles,
-- allows to derive Born's rule in the limit of a perfect von-Neumann measurement (the only case where Born's rule has empirical content),
-- has no collapse (except approximately in non-isolated subsystems).
-- uses no concepts beyond what is taught in every quantum mechanics course,
No other interpretation combines these merits.
The thermal interpretation leads to a gain in clarity of thought, which results in saving a lot of time otherwise spent in the contemplation of meaningless or irrelevant aspects arising in poor interpretations.
The thermal interpretation is based on the observation that quantum mechanics does much more than predict probabilities for the possible results of experiments done by Alice and Bob. In particular, it quantitatively predicts the whole of classical thermodynamics.
For example, it is used to predict the color of molecules, their response to external electromagnetic fields, the behavior of material made of these molecules under changes of pressure or temperature, the production of energy from nuclear reactions, the behavior of transistors in the chips on which your computer runs, and a lot more.
The thermal interpretation therefore takes as its ontological basis the states occurring in the statistical mechanics for describing thermodynamics (Gibbs states) rather than the pure states figuring in a quantum mechanics built on top of the concept of a wave function. This has the advantage that the complete state of a system completely and deterministically determines the complete state of every subsystem - a basic requirement that a sound, observer-independent interpretation of quantum mechanics should satisfy.
The axioms for the formal core of quantum mechanics are those specified in the entry ''Postulates for the formal core of quantum mechanics'' of Chapter A4 of my theoretical physics FAQ at http://arnold-neumaier.at/physfaq/physics-faq.html#postulates . There only the minimal statistical interpretation agreed by everyone is discussed. The thermal interpretation goes far beyond that, assigning states and an interpretation for them to individual quantum systems, in a way that large quantum systems are naturally described by essentially classical observables (without the need to invoke decoherence or collapse). The new approach is consistent with assigning a well-defined (though largely unknown) state to the whole universe, whose properties account for everythng observable within this universe.
The fundamental mathematical description of reality is taken to be standard quantum field theory. It doesn't matter for the thermal interpretation whether or not there is a deeper underlying deterministic level.
In my thermal interpretation of quantum physics, the directly observable (and hence obviously ''real'') features of a macroscopic system are the expectation values of the most important fields Phi(x,t) at position x and time t, as they are described by statistical thermodynamics. If it were not so, thermodynamics would not provide the good macroscopic description it does.
However, the expectation values have only a limited accuracy; as discovered by Heisenberg, quantum mechanics predicts its own uncertainty. This means that <Phi(x)> is objectively real only to an accuracy of order 1/sqrt(V) where V is the volume occupied by the mesoscopic cell containing x, assumed to be homogeneous and in local equilibrium. This is the standard assumption for deriving from first principles hydrodynamical equations and the like. It means that the interpretation of a field gets more fuzzy as one decreases the size of the coarse graining - until at some point the local equilibrium hypothesis is no longer valid.
This defines the surface ontology of the thermal interpretation. There is also a deeper ontology concerning the reality of inferred entities - the thermal interpretation declares as real but not directly observable any expectation <A(x,t)> of operators with a space-time dependence that satisfy Poincare invariance and causal commutation relations.
These are distributions that produce measurable numbers when integrated over sufficiently smooth localized test functions.
Deterministic chaos is an emergent feature of the thermal interpretation of quantum mechanics, obtained in a suitable approximation. Approximating a multiparticle system in a semiclassical way (mean field theory or a little beyond) gives an approximate deterministic system governing the dynamics of these expectations. This system is highly chaotic at high resolution. This chaoticity seems enough to enforce the probabilistic nature of the measurement apparatus. Neither an underlying exact deterministic dynamics nor an explicit dynamical collapse needs to be postulated.
The same system can be studied at different levels of resolution. When we model a dynamical system classically at high enough resolution, it must be modeled stochastically since the quantum uncertainties must be taken into account. But at a lower resolution, one can often neglect the stochastic part and the system becomes deterministic. If it were not so, we could not use any deterministic model at all in physics but we often do, with excellent success.
This also holds when the resulting deterministic system is chaotic. Indeed, all deterministic chaotic systems studied in practice are approximate only, because of quantum mechanics. If it were not so, we could not use any chaotic model at all in physics but we often do, with excellent success.
rogerl said:1. How does your model explain the double slit experiment? In between emission and detection.. what is the electron or buckyball doing? How come they can shoot this one at a time and after many hours or days, interference patterns still show up?
2. How does your model explain Bell's Theorem at 30 Billion light years correlation?
3. How does quantum tunneling work? Is your particle always a particle or does it shapeshift between wave or particle?
Feynman said the double slit is the only mystery. If one can solve it. Then everything is solved. So pls. don't forget to explain well the double slit experiment.
In that series of slides you write on p. 57-58,A. Neumaier said:For Bell's theorem, see
http://arnold-neumaier.at/ms/lightslides.pdf
It seems to me you completely misunderstand Bell's proof here. The proof deals with any theory where the specification of the state of a region of spacetime can be broken down into a set of local facts about the state of each point--what Bell called local "beables"--and where the state at each point in space and time can only be causally influenced by local states in the past light cone of that point. This would certainly apply to classical field theories like classical electromagnetism!Since the quantum mechanics of a single photon is that of the Maxwell equations, the experiment can be explained by the classical Maxwell equations, upon interpreting the photon number detection rate as being proportional to the beam intensity.
This is a classical description, not by classical particles (photons) but by classical waves.
Thus a classical wave model for quantum mechanics is not ruled out by experiments demonstrating the violation of the traditional hidden variable assumptions.
Therefore the traditional hidden variable assumption only amounts to a hidden classical particle assumption.
And the experiments demonstrating their violation only disprove classical models with particle structure.
With an additional comment about 1), if it's ambiguous what it means to say "broken down into a set of local facts":1. The complete set of physical facts about any region of spacetime can be broken down into a set of local facts about the value of variables at each point in that regions (like the value of the electric and magnetic field vectors at each point in classical electromagnetism)
2. The local facts about any given point P in spacetime are only causally influenced by facts about points in the past light cone of P, meaning if you already know the complete information about all points in some spacelike cross-section of the past light cone, additional knowledge about points at a spacelike separation from P cannot alter your prediction about what happens at P itself (your prediction may be a probabilistic one if the laws of physics are non-deterministic).
Would you agree that 1) and 2) would cover classical field theories? If so it's not too hard to show that this alone is sufficient to derive Bell inequalities using arguments about the past light cones of the two regions of spacetime where experiments are performed and how specification of all local facts in the cross-section of one region's past light cone can "screen off" any correlations with facts about the other region, see my summary in [post=3248153]this post[/post] along with the link to the paper by Bell that explains the argument in more detail. If you don't find the argument convincing, perhaps we could discuss it in more detail...Keep in mind that 1) doesn't forbid you from talking about "facts" that involve an extended region of spacetime, it just says that these facts must be possible to deduce as a function of all the local facts in that region. For example, in classical electromagnetism we can talk about the magnetic flux through an extended 2D surface of arbitrary size, this is not itself a local quantity, but the total flux is simply a function of all the local magnetic vectors at each point on the surface, that's the sort of thing I meant when I said in 1) that all physical facts "can be broken down into a set of local facts". Similarly in certain Bell inequalities one considers the expectation values for the product of the two results (each one represented as either +1 or -1), obviously this product is not itself a local fact, but it's a trivial function of the two local facts about the result each experimenter got.
JesseM said:In that series of slides you write on p. 57-58,
It seems to me you completely misunderstand Bell's proof here. The proof deals with any theory where the specification of the state of a region of spacetime can be broken down into a set of local facts about the state of each point--what Bell called local "beables"--and where the state at each point in space and time can only be causally influenced by local states in the past light cone of that point. This would certainly apply to classical field theories like classical electromagnetism!
Please open a new thread for that...JesseM said:If you don't find the argument convincing, perhaps we could discuss it in more detail...
unusualname said:Missed this above, yes I suppose it wasn't very polite, sorry for any offense, I thought it was kind of cute at the time, but I can see how it comes across as just plain rude.
A. Neumaier said:I have my own interpretation.
The thermal interpretation is superior to any I found in the literature, since it
-- acknowledges that there is only one world,
-- is observer-independent and hence free from subjective elements,
-- satisfies the principles of locality and Poincare invariance, as defined in relativistic quantum field theory,
-- is by design compatible with the classical ontology of ordinary thermodynamics
-- has no split between classical and quantum mechanics,
-- applies both to single quantum objects (like a quantum dot, the sun or the universe) and to statistical ensembles,
-- allows to derive Born's rule in the limit of a perfect von-Neumann measurement (the only case where Born's rule has empirical content),
-- has no collapse (except approximately in non-isolated subsystems).
-- uses no concepts beyond what is taught in every quantum mechanics course,
No other interpretation combines these merits.