Talk:Quantization (physics)

needs not to refer to "field theory" in beginning
"field theory" is wtf, people. It is best to use technicals immediately after fundamentals. —Preceding unsigned comment added by 72.242.110.218 (talk) 18:32, 15 September 2009 (UTC)

Style collaboration proposal
I think this page is a very valuable resource for much of the QFT and HEP sections of the encyclopedia. Very commendable work. I have one stylistic complaint though. Please don't interpret this as belittling anyone's past efforts: I fully appreciate how difficult it is to write up material like this. So here goes &mdash;

The descriptions seem rather abstract. I'm a working physicist, and I had to stop and re-read parts every now and then. I wonder what fraction of graduate students in particle physics would recognize the descriptions in one reading without having to stop and think. As the first comment on this page indicates, we don't need to write this page for the amorphous public, but keeping science undergrads in mind would not be a bad idea. Would it be possible to start a collaboration to rework this material? Bambaiah 06:52, Jun 2, 2005 (UTC)


 * Sorry, there have been more mathematicians on WP than physicists to date. Are you saying you want to re-write, but want someone's help? I could certainly blast this into something more readable; unfortunately, it would also get a lot longer. Quantization is a hot topic these days. I was planning on expanding on both geometric and deformation quantization. linas 15:13, 2 Jun 2005 (UTC)

Well, I skimmed the article a bit more; what is it that you want to do to it? In many ways, this article is not bad; I guess what's missing is maybe an undergrad-level introduction; but note also that undergrad level quantization is totally ad hoc, and consists in mostly hacking on the Schreodinger equation and introducting the spherical harmonics. What can be said that would be "simple"? I guess one could say in simpler terms that the canonical momentum is $$-i\partial/\partial x$$ and so ergo schreodinger and Klien eqn and Dirac eqn. Call this section "ad hoc quantization" or "first quantization" and then state that "canonical quantization" is the modern math formulation of ad hoc hamiltonian based quantization. Probably canonical quant should be made into its own article.

By contrast, second quantization already has its own article (albeit its nearly empty) and path integral has a large excellent article. BRST is rather throughly opaque and needs intro ... yikes! I did once read in BRST decades ago, but I didn't understand it then. I was going to expand on geometric quantization and also I've got a copy of an excellent 1977 paper on deformation quant that I was planning on studying, but I was planing on strecthing this all out for half a year or more :) WP is missing articles on some of the more basic background material.  I am, ahem, an amateur having a mid-life crisis wishing I hadn't left academia; so this is spare time activity for me.   linas 05:07, 3 Jun 2005 (UTC)


 * I tried to demonstrate. what I wanted to do through two major edits:
 * The first was the edit of the section "canonical quantization". I created a more detailed article on that topic (which is still not complete) and reduced the section to an introduction to that article. I also moved the technical material in this section to a section of its own in the article on "canonical quantization". Perhaps the article on "second quantization" becomes redundant now and needs to be merged either with "Quantum field theory" or "canonical quantization".
 * The second was the edit of the introduction and the introductory part of section 1. Many of the points touched upon there were either straight quantum mechanics, or philosophy of quantum mechanics. They can be reduced to a reference. I think it reads better now &mdash; clearly not npov :), so a second opinion on this would be very good to have.
 * As for me, I'm relaxing after a long computation, so I'll also not keep up this pace for long. Bambaiah 09:37, Jun 4, 2005 (UTC)

Reviewing edits now ... one big problem with the edits is that quantization isn't just about field theory; we don't even know how to reliably quantize simple systems. e.g. canonical quantization, geometric quantization and deformation quantization are about first quantization of simple finite-dimensional mechanical systems, not second quantization of fields. Case in point the Hilbert-Polya conjecture states that the Riemann hypothesis is the first quantization of a very very simple one-d Hamiltonian; numerous hints show that its somehow "simpler" than the harmonic oscillator. We neither know what that Hamiltonian is nor how to quantize it. So my interest is in number theory, not field theory per se; the quantization is to try to get at a basic conjecture of number theory.

This is why I mumbled about "ad hoc" quantization such as the Schroedinger equation. Schroedinger equation is a recepie for first quantization that sort-of works in some cases. The article you wrote on canonical quantization will need to be moved to canonical second quantization. These are distinct concepts having vastly different theories. linas 17:25, 4 Jun 2005 (UTC)


 * I appreciate your feedback. I'm not sure exactly what you mean by applications to number theory. I'll spend some time talking to number theorists about the example you have given. I appreciate your second point, and taken your critique into account by modifying the article on canonical quantization. Quantum mechanics and quantum field theory are distinct things, but not vastly different. Dirac's book [ISBN 0198520115] clarifies, I think. Bambaiah 07:23, Jun 6, 2005 (UTC)

I doubt your number theorist friends will have a clue; the relationship is pushed mostly by physicists, e.g. Sir Michael Berry. The relation is speculative, but it has a hold of my imagination. I don't know that there's more than one paper a year published on this; but I don't know. Some nuclear physics people studying Gaussian unitary ensembles may be aware of this. Ditto for any quantum-chaos types; the Riemann Hamiltonian looks to be "quantum chaotic", it has all the right statistics to be chaotic.

Mathematically speaking, QFT and QM are very very different. The techniques used to pose and solve the shroedinger eqn. e.g. hydrogen atom, are nothing at all like second quantization. Only to physicists do these things look alike. :) I'd like to have this article be about the topic of "how to quantize" and not about "what is perturbative field theory" which is the current standard treatment of second quantization. linas 14:51, 6 Jun 2005 (UTC)

I've been alluding to difficulty of quantizting simple systems. Here's an explicit example. Pick a riemann surface, any surface. They're all Kahler manifolds, they're all symplectic manifolds. They're all 2D phase spaces, with exactly one x and one p coordinate. Pick a Hamiltonian, any hamiltonian. For symplectic manifolds, a hamiltonian is a real-valued function on the phase-space/symplectic manifold. Just to keep things simple, pick the Hamiltonian $$H=p^2/2m$$, its just a pure kinetic term. Or pick the SHO $$p^2/2m + kx^2/2$$ if you wish. Now quantize it, by any means desired. Tell me what the eigenstates are, what the energy levels are. Hah. Not so easy, eh? And mind you, this is just a plain old 1-dimensional problem. It gets worse in higher dimensions, never mind infinite dimensions. linas 15:56, 6 Jun 2005 (UTC)


 * Ok, let's pick the SHO and quantize it by RCQ. Eigenstates? Really easy. Energy levels? Not a problem. (Hmm... But the energy levels turn out to be "incorrect": they start from zero. This is just because quantum Hamiltonian is defined differently.)


 * OK, Easy? Then explain it to me. Pick, for example, the Riemann surface $$\mathbb{H}/\Gamma_0(3)$$. Tell me what p and x are on this surface, then tell me how to quantize either the pure kinetic or the SHO, and tell me what the eigenstates are. The only two reimann surfaces I know how to quantize are the flat plane (the eigenstates are plane waves) and the sphere (the eigenstates are sphere harmonics). I don't know how to do any surfaces of negatvie curvature, refernces to textbooks or papers that do the math explicitly would be great. linas 22:54, 7 Jun 2005 (UTC)


 * Here's another simple example that I find eminently confusing. Review the article geodesic. Note the prominent place of the Hamiltonian there. How do I quantize that Hamiltonian? I would like to know.  linas 16:11, 11 Jun 2005 (UTC)

Application
The word "quantization" is not the exclusive property of field theory. Planck's law enforced the quantization of energy. Bohr postulated the quantization of angular momentum... --Ujm 08:30, 15 October 2006 (UTC)

Include Simplicity
A big problem with many of the Wiki scientific and technical articles including this one (and most college science texts---why the Dummies series of books are far more useful to the average student) is that they do not build from the simple to the complex starting from the level of someone with only the most rudimentary acquaintance with the subject-matter. Relying solely on links for terms is insufficient, particularly when the term-defining links are themselves heavy in jargon and poorly written. This makes the article virtually useless for the average Wiki user, and makes it more a tekkie blog. Tmangray 21:19, 28 December 2006 (UTC)


 * This complaint should be moved to Wikipedia talk:WikiProject Physics. This talk page is just for problems specific to this article on Quantization. JRSpriggs 08:25, 29 December 2006 (UTC) P.S. I am moving this section to the bottom of this page as that is normal practice for new sections of talk.

Actually, this complaint should not be moved to another section and should remain here, as it is relevant to this article. This Wikipedia entry is mostly useless to readers with only the basest understanding of quantum mechanics because the concepts are far out of reach and definitions are absent, which means it would be even more useless to the average reader. This entry should start by defining concepts of quantum mechanics in a concise manner using easy-to-understand analogies. After that introduction, the article should then proceed to build the case for how researchers have come to discover that some physical properties can be quantized (that is, their properties have discrete values that can be understood from measuring their interactions at the subatomic level). — Preceding unsigned comment added by 2602:306:8012:38A0:C5DE:4840:F975:BC00 (talk) 20:43, 22 May 2017 (UTC)

debate about putting an animation to explain quantization
I'm the author of this animation



which was added by JRafner to this article, but then removed by Xxanthippe who argued that "this gimmick conveys no content". Eventhough I understand the critic raised by Xxanthippe and appreciate the time he spent to consider this, I disagree with the opinion that there is no content. This animation indeed conveys a visual explanation of quantization for non experts in the field. This animation is part of a set of animations we created in our University with the same graphic langage to explain duality, tunnel effect, quantization, spin, and other fundamental notions of quantum physics. Eventhough different animations exist in the field, I did not see any other proposed in this article. Furthermore, all these animations are in licence creative commons and shared in commons.wikimedia so that anyone can download them and use for free. Many of our colleagues in USA and exchanged we had with the American Physical Society and science museums revealed that many people use these animations now in their university courses. I would therefore suggest to put it back because it is a valuable tool to understand the basics of quantum physics and help those who give courses about it too.

Can other contributors give their opinion in this unsettled debate ? — Preceding unsigned comment added by Jubobroff (talk • contribs) 12:28, 30 June 2014 (UTC)


 * The animation verges on the incomprehensible to somebody who knows something about the matter and will be totally meaningless to somebody who doesn't. It just doesn't come up to Wikipedia's standards. I have looked at the other animations you have produced, and there there are others that are not much good either. It needs informed professionals to do this work. You might like to take the matter to the Physics work group. Xxanthippe (talk) 22:49, 30 June 2014 (UTC).


 * I understand the concerns raised about these visual animation about quantum physics. I thank Xxanthippe to give us the opportunity to establish here that the Quantum Made Simple animations are indeed serious enough to meet wikipedia's criteria from a scientific point of vue. So let me give wikipedia's community a few references hereafter about these animations :


 * The authors and institutions responsible for it are informed professionals in the field of quantum and solid state physics from the CNRS french research agency and Universite Paris-Sud. All of them are full professors or assistant professors in condensed matter and quantum physics, all known on international level in their field of research, and all are teaching at graduate and undergraduate levels (for example : J. Bobroff, F. Bouquet, F.Bert, D. Clement].


 * The animations were produced and funded by very serious research institutions in physics : CNRS, Universite Paris-Sud, the French Physical Society and the american Institute of Complex Adaptative Matter led by top scientists in the field.


 * Now here are some references about the animations themselves and how they were received by the international scientific community :


 * - they were shown at the biggest physics conference, APS March Meeting 2013 in Baltimore, in an invited talk at the session Physics for Everyone and encountered a great approuval as quoted here described here.


 * - an article was published in Physics Today Vol 66, 9 , 60 (2013) which describes these animations and other productions of the same authors.


 * - Other physicists also approuved these productions, for example Clifford V. Johnson, a professor at the Department of Physics and Astronomy, at the University of Southern California in his in this article from his blog.


 * - The ICAM institute gives a clear description and approuval of the resulting animations in this website article.


 * - All these animations were put in the french wikipedia more than a year ago and have been widely used since then and never removed by the french wikipedia community.


 * I hope this list of references will help the wikipedia community to decide if the "Quantum Made Simple" animations are serious enough from a scientific point of vue to be displayed in wikipedia. Jubobroff (talk) 3 July 2014


 * Xxanthippe is quite right. This is a really bad animation. You need to understand the physics before it makes sense, and that is totally the wrong way round. A few academic endorsements mean only that the physics is technically correct, but that is worthless if the physics is not communicated. Or, to put it your way, it is serious enough but it is not clear enough. Take Xanthippe's advice. &mdash; Cheers, Steelpillow (Talk) 07:58, 5 July 2014 (UTC)


 * I'm in two minds on this one - it's not my style, but I appreciate that different people learn in different ways, so I think we should support people trying different ways to contribute to wikipedia. Another one in the series was added to Introduction to quantum mechanics recently, where it seems to work.  I'm not sure it works in this article, mainly because (as far as I can tell) this article isn't aiming to be a general "what does it mean for something to be quantized?", but instead it describes "a procedure for constructing a quantum field theory starting from a classical field theory."  Djr32 (talk) 22:20, 6 July 2014 (UTC)


 * I'm with Xxanthippe on this one. The animations aim at enthralling, but carry very little information and essentially no explanation or insight; they were created with the wrong target audience and purpose in mind. Unfortunately this means it could be better classified with advertisements and junk science presentations such as Bleep than as reference material. Wikipedia is meant to be a reference, not a textbook, and even less a place for oversimplified science memes. It may give a sense of quantization of energy levels in confined states (but then, this is a classical concept, e.g. vibrational modes of a guitar string), but it does not even start to give a sense of what quantization is really about, e.g. why a freely propagating electromagnetic field is quantized as photons. They're nice as catchy "fluff", and hence their potential use associated with presentations; they serve much the same purpose as do the pretty girls draped over cars at car shows. —Quondum 05:33, 7 July 2014 (UTC)


 * Thanks to Quondum I now understand where the problem comes from : the animation is not at the proper place, namely it is in the "quantization" general article which refers in fact to various facts in physics and mathematics, while it should be instead in Particle in a box article which very precisely describes what we call quantization in quantum solid state physics. Eventhough we still disagree with some general comments made about the scientific validity and clarity of these animations, I want to thank you Quondum, Djr32 and Xxanthippe for helping us to figure this out. Jubobroff (talk) — Preceding undated comment added 14:10, 7 July 2014 (UTC)


 * I agree it fits much better in Particle in a box. The wider question of what is the best way to explain QM remains, but I think that might be a level beyond what we're going to be able to answer in this talk page... Djr32 (talk) 21:11, 7 July 2014 (UTC)
 * I don't think it is even good enough for Particle in a box. Xxanthippe (talk) 22:46, 7 July 2014 (UTC).


 * I totally agree with comments noting that this article (Quantization) is not the right place for this animation. What it represents is the quantification of energy levels available to a particle in a well potential - with application to solid state physics in mind. As such, the quantization article is much more general, and does not benefit from it. I do think that such an animation has a place in the article Particle in a box, in the early paragraphs were the basic principles are presented. It is true that this animation will not bring any new information to already in-the-know scholars, as some of the comments above clearly demonstrate. But an encyclopedia page is not dedicated only to scholars or physics students. As someone who knows about equations, I like the animation that is currently opening the page Particle in a box, because I already know what it means. Imagine someone with no strong background in quantum physics but curious about it opening that page; I argue that the animation discussed here would give him a better visualization of the physics in play. Yes, it is only a visualization of the process, not the real thing, but nevertheless a correct visualization: there are no gross errors hiding behind it. I guess this discussion really comes to that: are the quantum-physics wiki pages dedicated to physics students and scholars, or are they also dedicated to laymen – with what it implies in term of visualizing something that is in essence non visualizable. — Preceding unsigned comment added by Fbouquet (talk • contribs) 06:51, 9 July 2014 (UTC)

Missing formulas
In the section "Geometric quantization", last paragraph, there are references to missing formulas. The text, in this form, is not understandable — Preceding unsigned comment added by Giorast (talk • contribs) 07:58, 25 December 2016 (UTC)

What is "It"?
The second sentence of this article is in parentheses (which is a problem in itself) and it references an "It". I can only see it referring to quantization itself, but that word doesn't make sense in that sentence. "Quantization is a procedure for constructing a quantum field theory starting from a classical field theory." Quantization is not a procedure, which makes this parenthetical statement confusing. What procedure could be used to construct a QFT from a CFT? Is it saying anything other than just name dropping QFT and CFT? — Preceding unsigned comment added by Babenzele (talk • contribs) 09:21, 9 December 2019 (UTC)


 * I partially addressed your gripe, by marginalizing the field theoretical focus to one on plain QM, where the ordering ambiguities are more tractable. Indeed, field quantization is largely a functor, where canonical quantization is concerned.  I left handles for non-canonical field quantization around, but the article is meant to be a traffic cop to searching readers, organizing and dispatching the various quantization strands involved. I move two paragraphs from Geometric to  Deformation quantization.Cuzkatzimhut (talk) 14:51, 8 October 2021 (UTC)