If you are aware of an interesting new academic paper (that has been published in a peer-reviewed journal or has appeared on the arXiv), a conference talk (at an official professional scientific meeting), an external blog post (by a professional scientist) or a news item (in the mainstream news media), which you think might make an interesting topic for an FQXi blog post, then please contact us at forums@fqxi.org with a link to the original source and a sentence about why you think that the work is worthy of discussion. Please note that we receive many such suggestions and while we endeavour to respond to them, we may not be able to reply to all suggestions.

Please also note that we do not accept unsolicited posts and we cannot review, or open new threads for, unsolicited articles or papers. Requests to review or post such materials will not be answered. If you have your own novel physics theory or model, which you would like to post for further discussion among then FQXi community, then please add them directly to the "Alternative Models of Reality" thread, or to the "Alternative Models of Cosmology" thread. Thank you.

Please also note that we do not accept unsolicited posts and we cannot review, or open new threads for, unsolicited articles or papers. Requests to review or post such materials will not be answered. If you have your own novel physics theory or model, which you would like to post for further discussion among then FQXi community, then please add them directly to the "Alternative Models of Reality" thread, or to the "Alternative Models of Cosmology" thread. Thank you.

Forum Home

Introduction

Terms of Use

RSS feed | RSS help

Introduction

Terms of Use

*Posts by the author are highlighted in orange; posts by FQXi Members are highlighted in blue.*

RSS feed | RSS help

RECENT POSTS IN THIS TOPIC

**Marcel-Marie LeBel**: *on* 10/10/11 at 23:07pm UTC, wrote LC At the speed of light, time stops. Then, a true time duration can be...

**Lawrence B. Crowell**: *on* 10/10/11 at 18:29pm UTC, wrote The “box” or infinite well is a potential which enters into the...

**Marcel-Marie LeBel**: *on* 10/9/11 at 0:26am UTC, wrote LC Or, maybe you understood it almost right. Be it Stern-Gerlach or Zeeman...

**Lawrence B. Crowell**: *on* 10/5/11 at 15:37pm UTC, wrote You seem to be saying something almost right. The context in the case of a...

**Marcel-Marie LeBel**: *on* 10/2/11 at 19:48pm UTC, wrote LC re: your last sentence and later statement below... "Quantum...

**Karl Coryat**: *on* 9/30/11 at 23:15pm UTC, wrote The "final theory" will be a specific informational interpretation of...

**Juan Ramón González Álvarez**: *on* 9/28/11 at 10:59am UTC, wrote The quantum state evolves according to the Schrödinger equation ONLY for...

**Lawrence B. Crowell**: *on* 9/27/11 at 21:31pm UTC, wrote I am saying that QM is deterministic in the sense that that a wave...

FQXi FORUM

November 29, 2022

This raises some interesting questions. I read Brukner's "Quantum State Preparation with Universal Gate Decompositions," which seems related to this matter. I am also curious as to whether this has some relationship to the cellular automata idea of 't Hooft. This is not so much to support the idea of hidden variables, but more in the way in which a continuum description of configuration variables is related to the quantum states they represent.

Cheers LC

report post as inappropriate

Cheers LC

report post as inappropriate

LC

re: your last sentence and later statement below...

"Quantum mechanics involves non-contextual observables, but the act of performing a measurement imposes a context"

Isn't the context you speak of in the measurement about putting the squeeze on degrees of freedom leading to a temporary quantization of a normally continuous variable? Like between energy levels of a free electron and those of an electron in an atom?

Marcel,

report post as inappropriate

re: your last sentence and later statement below...

"Quantum mechanics involves non-contextual observables, but the act of performing a measurement imposes a context"

Isn't the context you speak of in the measurement about putting the squeeze on degrees of freedom leading to a temporary quantization of a normally continuous variable? Like between energy levels of a free electron and those of an electron in an atom?

Marcel,

report post as inappropriate

You seem to be saying something almost right. The context in the case of a spin 1/2 particle is the orientation of the Stern-Gerlach apparatus. The observer chooses the orientation of the instrument and the basis upon which the measurement is made.

Cheers LC

report post as inappropriate

Cheers LC

report post as inappropriate

LC

Or, maybe you understood it almost right. Be it Stern-Gerlach or Zeeman or any other measurement, measurement applies an additional constraint which comes to be one more and last quantum number. The measurement is making it quantized. Same as a particle in a box; constraint is forcing the temporary quantization.

Marcel,

report post as inappropriate

Or, maybe you understood it almost right. Be it Stern-Gerlach or Zeeman or any other measurement, measurement applies an additional constraint which comes to be one more and last quantum number. The measurement is making it quantized. Same as a particle in a box; constraint is forcing the temporary quantization.

Marcel,

report post as inappropriate

Phrases as «According to standard interpretations, quantum objects do not have well-defined properties, until those properties are measured by an observer.» are repeated too often in the literature but do not agree with what quantum mechanics really says.

Moreover, contrary to claims in this article, there exist chemical and physical processes that cannot be explained by quantum mechanics. Several extensions are known and used in the lab. For instance, "The Liouville Space Extension of Quantum Mechanics". T. Petrosky and I. Prigogine. Adv. Chem. Phys. 99, 1-120.

Of course that extension emphasize still more inherent randomness of nature and this is a very important point, explains how randomness survives at the classical level under certain conditions: Poincaré Resonance and the Extension of Classical Dynamics 1996: Chaos, Solitons and Fractals 7(4), 441-498

I.e. randomness is not restricted to quantum systems.

And generalizations of their theory are already at our hand. Finally, information theory has not provided any new result that were not known previously.

report post as inappropriate

Moreover, contrary to claims in this article, there exist chemical and physical processes that cannot be explained by quantum mechanics. Several extensions are known and used in the lab. For instance, "The Liouville Space Extension of Quantum Mechanics". T. Petrosky and I. Prigogine. Adv. Chem. Phys. 99, 1-120.

Of course that extension emphasize still more inherent randomness of nature and this is a very important point, explains how randomness survives at the classical level under certain conditions: Poincaré Resonance and the Extension of Classical Dynamics 1996: Chaos, Solitons and Fractals 7(4), 441-498

I.e. randomness is not restricted to quantum systems.

And generalizations of their theory are already at our hand. Finally, information theory has not provided any new result that were not known previously.

report post as inappropriate

Quantum mechanics is perfectly deterministic. The wave equations are not stochastic. However, the Fourier components of a wave are amplitudes which define probabilities as the modulus squared. Stochasticity enters into the picture with measurements or outcomes. Quantum mechanics involves non-contextual observables, but the act of performing a measurement imposes a context. This means measurements, or the contextual basis for quantum observation is not something which is predicted by quantum mechanics. The outcomes satisfy a Kolmogoroff entropy, and define the maximal randomness for a set of outcomes. This is not computable by the Chaitan-Kolmogoroff theorem, which suggests there is some form of incomputable aspect to quantum measurement. In other word context is not computable by QM, but contextuality still exists with respect to observations.

Cheers LC

report post as inappropriate

Cheers LC

report post as inappropriate

Quantum mechanics is a non-deterministic theory, as has been known for more than a century. The Schrödinger equation is not stochastic and thus cannot explain measurement processes (nor other processes) as any basic textbook emphasize.

The measurement process in quantum mechanics is covered by the measurement postulate (again check any textbook), but this postulate does not describe the details of the measurement. The details are described in the generalizations of quantum mechanics, as the one cited above.

At the more simple level of theory, one obtains a stochastic generalization of the Schrödinger equation (sometimes named Ito-Schrödinger). This stochastic generalization allows for a dynamical description of the transition from amplitudes to probabilities (a transition "from potentialities to actualities" in Born's words).

The Kolmogoroff entropy is not the thermodynamic entropy of the physical system, and it is rather unuseful unless complemented by a non-unitary dynamical law describing the interaction between the system under observation and the measurement system. In my own FQXi forum I gave more details about stochastic generalizations of the Schrödinger equation and the several approximations involved in quantum mechanics.

report post as inappropriate

The measurement process in quantum mechanics is covered by the measurement postulate (again check any textbook), but this postulate does not describe the details of the measurement. The details are described in the generalizations of quantum mechanics, as the one cited above.

At the more simple level of theory, one obtains a stochastic generalization of the Schrödinger equation (sometimes named Ito-Schrödinger). This stochastic generalization allows for a dynamical description of the transition from amplitudes to probabilities (a transition "from potentialities to actualities" in Born's words).

The Kolmogoroff entropy is not the thermodynamic entropy of the physical system, and it is rather unuseful unless complemented by a non-unitary dynamical law describing the interaction between the system under observation and the measurement system. In my own FQXi forum I gave more details about stochastic generalizations of the Schrödinger equation and the several approximations involved in quantum mechanics.

report post as inappropriate

I am saying that QM is deterministic in the sense that that a wave function, perfectly prepared in a lab, evolves as ψ(t) = U(t – t_0)ψ(t_0) in a completely predictable manner. However, to back this data out one must perform measurements on identically prepared systems. The stochastic nature of QM enters in with measurement itself.

Cheers LC

report post as inappropriate

Cheers LC

report post as inappropriate

Measurements in quantum mechanics are a problem because of the fact the scale of the instrument the instruments are not only giving data but also at the same time influencing the object, and so it can even become impossible, like trying to measure a living fly with a centimeter, once you pin down the fly he is dead, you can measure it, but is is no longer a fly, the essence has gone. It is not very scientific but it is how I explain the uncertainty principle.

keep on thinking free

Wilhelmus

report post as inappropriate

keep on thinking free

Wilhelmus

report post as inappropriate

The "final theory" will be a specific informational interpretation of quantum mechanics that can be tested and counter-falsified. That's what we need to look for.

report post as inappropriate

report post as inappropriate

Login or create account to post reply or comment.