Talk:Quantum mechanics/Archive 8

Vancouver interpretation of quantum mechanics
Albert Einstein did the impossible, twice (thrice with qm) redefining the rules of the mind game termed Science. But a true genius of Einstein is only surfacing now, when we may discuss Einsteinian variables in Vancouver interpretation of quantum mechanics. Totally neglected and misunderstood, Einstein knew deeply in his heart that he was right but perhaps only Kurt Godel and Paul Dirac were able to understand his motivation. It took a lot of time for me to understand the significance of Einsteinian variables when I was trying to conceptualize the merger of the Buddhist mathematical logic (mathematics is, necessarily, deductive, according to Whitehead; hence casual) and the key aspects (tensors) of general relativity, which is based on geometrodynamics. Moreover, Eisntein was right again in questioning the violation of Einstenian causality and here again we are learning from a sea of his wisdom and intuition. The Buddhist Shuniata concept, for example as explained in the books authored by Dalai-Lama, (for a reduced level of representation please read Urgen Tulku), suggests that mind is one, but it is different. The one might say it is described by a wave function Psi, as I tried to argue in a draft of a paper sent in 2009 to the Journal of Consciousness studies, after Scott Hagan kindly reviewed seven drafts of it. Unfortunately a publication was declined in 2010 and with a loss of my archive I stopped working on an article and started to think about number theory, about 0 and 1. Since many of my notes have reappeared in Connes, Wang and other papers about Einsteinian variables, that were my major part of investigation, I decided that I will stop working until after peace of mind is reached, perhaps congruently with a positive development in the contacting of unknown to me Mr. Charles Wang. Situation is uncertain to say the least but I can assure everyone that I have no other important association apart from a Buddhist movement “Diamond Way” of Kagiu-pa lineage, Tibet, China. Being my self from Kazakhstan, I was nurtured among geometrical motives of Kazakh culture and steppe, these motives been Chinese. As the humble Buddhist I take advice from Dalai-Lama’s teachings, the latest sample of it is enclosed. I consider my self and my Buddhist school Kagiu-pa as part of the vast Chinese Cultural Empire, with Tibetan Buddhism being its crown both geographically and scientifically. Quantum mechanics is a Queen of science, She is the One. Zeroness, or nothingness, is a phase space that would contain all things. Their symmetry is hidden. Ancient Greek philosopher Heraclit would say that hidden symmetry is more important than open one. However when we met superposition and Arnold described a smooth variable as an example of its usage in representing Einstenian variables, only then it became possible to jump on a bandwagon of general gauge theories with a view to lead a train of thought. However, as Sir Roger Penrose has noted in his beautiful book “ The Road to Reality”, something was “missing”, perhaps some key “ingredient” to the kitchens of super good mathematicians. Sir Eddington was right in telling that super good (all of them) mathematicians don’t really know what they are doing. Sir Edduington knew what he was telling. That probability distribution of electrons and metric tensor g are related was noted in his outstanding book “New Pathways in Science”. To be honest, and we remember that honesty is the best policy; Einstein already knew all the key ingredients by their names. Moreover, Einstein has personally produced two of those quantities, namely quantum and tensor, the Fundamental one. In addition, Einstein, though totally neglected (let me please discuss Kurt Godel and Paul Dirac cases separately), perfectly knew that relativistic sand and hidden variables, hence Einsteinian variables, are key ingredients indeed. Not only Einstenian intuition exceeded all reasonable expectations in identifying two of the key ingredients (like salt and pepper), but Einstein also directed the research towards obtaining final recipe by establishing Einstenian variables and the Einsteinian causality as something self-evident. Einstein has produced, named and described all the ingredients we need to consistently explain the four-dimensional bake that our consciousness apparently prepares. Please let me please state that in spite of (unproven as yet) correspondence between Buddhism, Shuniata and a science (as formulated by Einstein), this hypothesis is purely academic and it’s merit remains to be seen. Practically, I am a Russian citizen and currently reside in the beautiful British Columbia, in Vancouver. Needless to say that I have nothing to do with publication of my notes in Internet under different names (Connes, Wang etc). Finally, let me assure everyone one that I am a very peaceful person and that all rumors about my relationship with Sir Roger Penrose are greatly exaggerated. Sir Roger Penrose is in line with the brilliant generation of the likes Professor Paul Dirac, Professor Stephen Hawking. I did a translation of Professor Hawking’s book “A Briefer History of Time”. Professor Paul Dirac has made more than we think, too. Honesty is the best policy; we have to understand that our giants, starting with Einstein, are very factual today. It would take a genius of Sir Roger Penrose, with his background in general relativity, to explain to us what are the full implications of Einstenian variables across the board. I would like to study geometry from Sir Roger Penrose, and hopefully one of my letters to Sir Roger Penrose would be returned with an invitation for a cup of tea enclosed. I don’t want to initiate a discussion about Poincare just for a moment, and Kurt Godel’s exact solution of Einstein’s general relativity should wait as well. I am personally inclined to investigate transcendent numbers in more details. Hopefully, an uncertainty surrounding my status in Canada would be resolved, and I would be able to peacefully live in astonishing Vancouver, where everyone is treated with respect. Karma-pa chenno. —Preceding unsigned comment added by 24.84.38.166 (talk) 22:44, 30 June 2010 (UTC)
 * Citation, please. WP is not for original research. Bkalafut (talk) 19:27, 1 July 2010 (UTC)

This guy has never heard of paragraphs. —Preceding unsigned comment added by 88.104.101.94 (talk) 20:40, 15 September 2010 (UTC)


 * I'm reminded of http://math.ucr.edu/home/baez/crackpot.html, though the author has misspelled Einstien and Hawkins 178.7.97.63 (talk) 22:17, 13 January 2011 (UTC)


 * I'm not all too confident with Wikipedia guidelines on discussion pages, but doesn't someone have one at disposal to justify deleting this?

If this is allowed to stay, I can provide you with some more crackpot copypasta to fill up hundreds of pages, rendering the discussion page unusable. So he "can live in astonishing Vancouver" or wants to have tea with Roger Penrose... seriously! This does not belong here! Vandroiy (talk) 20:18, 13 March 2011 (UTC)

classical desription of orbiting charges
Can anyone who has edited this page write a complete description (all 'classical' ideas included) of two 'orbiting' charges, and describe why it fails? Please include it. And I don't mean the textbook version. — Preceding unsigned comment added by Littlefdsa (talk • contribs) 23:43, 23 April 2011 (UTC)


 * This page is for discussing improvements to the associated article, but we do have a Reference Desk to discuss this sort of question. Please do be aware of WP:HOMEWORK, though. - 2/0 (cont.) 08:27, 24 April 2011 (UTC)

physic and mathematics hilberts questions
What distinguishes 'modern' physics form math mathematical modeling? I ask because 'modern' physics differentiates itself from normal physics in that you are asked to excuse your normal experiences in judging things (and, the excuse is normally: it is mathematically complicated). And more importantly, a simple person is relegated to rely on others experiences (I can set up a force table, but not a cyclotron). And when a simple question has been put to phd's they scramble to recount the text they've read. I'm asking about the correlation/causation theme. This subject is not discussed on any related page, so links would be needed. as and aside, are there any links to mathematical attempts to adapt to the 1/r problem? — Preceding unsigned comment added by Littlefdsa (talk • contribs) 23:56, 23 April 2011 (UTC)

Rationalists Beware
For every endeavor, there is an Art and a Science. Quantum Mechanics is the art of Quantum Theory while Quantum Physics is the science of Quantum Theory. Quantum Mechanics has many uses but is primarily limited to thought experimentation and wowing potential investors. (See, Dark Matter, Multiverses, Unicorns and Pixies.)

You will note the linked assets do not, as yet, exist. These voids cripple the very nature of this article.

In addition, Causality is dismissed within QM. What a luxury! To simply suggest or imply "God did it" is to absolve all rationality. Doing so did not work for Ptolemy, Newton or Einstein, so the same cannot be allowed on Wikipedia. —Preceding unsigned comment added by Kempion (talk • contribs) 16:08, 3 May 2011 (UTC)


 * You are missing a concept, that of probability: "I believe that we do not know anything for certain, but everything probably." —Christiaan Huygens. The QM framework has probability amplitudes built-in, which was Max Born's contribution. --Ancheta Wis (talk) 16:17, 3 May 2011 (UTC)


 * Where is causality dismissed? Arguably, quantum gravity has issues with it, but that's a different matter entirely. Perhaps you mean the lack of determinism. Well, that's not exactly a luxury. --Sabri Al-Safi (talk) 09:50, 4 May 2011 (UTC)


 * I addressed the separation of the Art and Science. Since those are not defined elsewhere on Wiki, this suggests those who could add real contributions to Wiki are not... and probably for good reason. Kempion (talk) 02:26, 5 May 2011 (UTC)


 * It's undoubtedly an interesting question, and it applies to a great many more things than quantum theory. I don't think the dichotomy is anywhere near as black and white as "quantum mechanics is the art, quantum physics is the science" - I think it's much more difficult to separate the art from the science in this manner. A great many thought experiments have inspired actual tests of hypothesis; conversely, experimental results inspire thinkers to chew on the consequences and come up with further thought experiments. The divide between theoreticians and experimentalists may be fairly clear cut and well-documented these days. However, philosophising about art and science concepts within quantum theory has no place on wikipedia. --Sabri Al-Safi (talk) 07:43, 5 May 2011 (UTC)

QM (foundational) scientists - Prof. Riazuddin?
Should Prof. Riazuddin be listed among such founders and developers of quantum mechanics (QM) as e.g. Planck, Heisenberg, and Bell, among the Scientists listed in the summary pane of the article, most of whom are also mentioned in histories of QM such as "The Quantum Ten" (Sheilla Jones; 2008)? Note also that even Einstein as an author of the EPR paper, and Feynman's co-Nobellists, Schwinger and Tomonaga, are omitted from the list.

This is not to discount Dr Riyazuddin's contributions to particle physics (see Google Scholar), but that is an area I would argue is distinct from the foundations of QT/QM/QFT. (For the same reason I would, though perhaps with a lesser justification, also question the inclusion of Riazuddin's mentor, Abdus Salam, in the list; a great man, no doubt, and a Nobellist too, but I suggest the electro-weak unification is more an application of QFT and Wigner's symmetry theories than a development of the foundations of QM/QFT per se).

Numerous others, before Salam and Riazuddin, could be counted among the founders, and later developers of the foundations, of QT/QM/QFT, from Aspect to Zeilinger. PaulGEllis (talk) 19:17, 22 May 2011 (UTC)


 * This is really an issue with the "template" rather than this actual article - see Template:Quantum_mechanics. It seems that user 184.0.105.21 is responsible for the Riazuddin inclusion, and likely the Abdus Salam one also; I note that most of their contributions revolve around Pakistani military technology, so I wouldn't be surprised if there was some sort of patriotic incentive for including these names. Personally, I don't know much about Salam or Riazuddin, and the template's discussion page has been very inactive, so for now I've let it slide. However, I'm inclined to agree with you that the names don't really belong with the likes of Heisenberg and Bell, and it seems appropriate to simply remove those names and add start a discussion on the template if there are issues. --Sabri Al-Safi (talk) 10:11, 23 May 2011 (UTC)
 * I have removed both names from the list in the template, which should indeed be kept concise. Regards, HaeB (talk) 10:10, 24 May 2011 (UTC)

Article is wrong
I see no confusion here. Some people, even some teaching physics, apparently use quantum physics interchangeably with quantum mechanics, which is not correct. Quantum mechanics is a subset of quantum physics, which includes quantum electrodynamics,. ...If one is concerned about particles and particle (matter) interaction, then referring to QM is appropriate. I don't believe a lay person will care, or even be aware of a distinction, unless that person has researched the fields of QM and QP.

There is no relativistic quantum mechanics. Both Dirac equations and Klein/Gordon wave equations are wrong equations, when examined in detail. The only consistent relativistic quantum formulation is relativistic quantum mechanics which is not a quantum mechanics in original sense and does not use original Dirac and Klein/Gordon. Quantum physics is more general than quantum mechanics. Quantum physics is the name for a collection of quantum theories: (non)relativistic quantum mechanics (also including quantum optics) and quantum field theory. Just like classical physics is a collective name for classical mechanics, electromagnetism and relativity. For instance, Electrodynamics is that part of science does not reduced to mechanics that explain electromagnetic phenomena. At quantum level, things are similar. Quantum physics is not a synonym for quantum mechanics. Mechanics is only about movement, electromagnetic phenomena cannot be reduced to mechanics alone, and thus there exists quantum electrodynamics. Also there is a quantum thermodynamics, that, of course, cannot be explained in pure mechanical terms. In fact, quantum thermodynamics cannot be constructed from usual Hilbert space formulation and one needs of more general formalisms, e.g. Liouville space and super-matrices.

As a final note, of course, quantum physics and quantum theory are not synonymous. Quantum physics is the collection of quantum theory more quantum experimentation. Or physics is not one of experimental sciences? — Preceding unsigned comment added by 174.6.162.113 (talk) 08:40, 19 July 2011 (UTC)


 * That's just like, your opinion maaan. --Sabri Al-Safi (talk) 10:49, 20 July 2011 (UTC)


 * The above anonymous comment is mostly wrong. Its true that "quantum mechanics" often refers to 1-particle, nonrelativistic QM, which is indeed a small subset of quantum theory. But quantum theory or quantum physics encompasses all of the areas that are governed by the Postulates of quantum mechanics, which includes relativistic quantum field theory, and yes, all the rest of "quantum physics". Isocliff (talk) 00:38, 21 July 2011 (UTC)

quantum
I have just seen a show about quantum mechanics about a cat poisoned and whether the cat is dead or alive in the closed box ect. I now know it's a popular therory so I know most know what I'm talking about if they are reading this here. Anyways, I often thought as a child this feeling that I knew something I hadn't actualy seen may not be true just because I knew it had to be the fact. Such as, I once locked myself out of the house as a child about 10 yrs of age and vividly recall locking the door on my way out. I was two hours early for church being my first time going there. So, not wanting to wander aimlessly around I thought it would be nice if I could go home and go back to bed. I started thinking about how I knew it was worthless going home to see if the door was unlocked but what if I told a freind I needed them to come over and open the door for me? Would it be locked for them just because I locked it or would it still be up in the air for someone elses chance to believe it was unlocked and would be? I even whent as far as trying to find local school chums up that morning to help with my theroy but none were up at the time and never thought to try it again, but have many other times felt that feeling of knowing something but did it happen? I heard the vase break in the taped up box, but is it broke? Not a great example but one of the simplest I've had and there has been more. Do or have other people expierinced this feeling like steping outside of yourself? — Preceding unsigned comment added by Thinkoutsidethecircle (talk • contribs) 23:05, 27 August 2011 (UTC)


 * I removed a leading space from your paragraph because it messes up wikipedia's formatting. Dauto (talk) 23:38, 27 August 2011 (UTC)


 * That's interesting (that you sometimes feel that way) but I don't see what quantum mechanics's got to do with it. Dauto (talk) 23:42, 27 August 2011 (UTC)


 * Stepping outside yourself...indeed interesting, with concerns of metaphysics and existentialism. ThisLaughingGuyRightHere  07:40, 28 August 2011 (UTC)

Quantum Relativity
I have just published a new theory I call Quantum Relativity on Wiki. You may wish to review my new theory in order to gain deeper insight into the topic. Feedback left at the Quantum Relativity discussion is also appreciated. Michael Stahl 12 September 2011 02:03, 12 September 2011 (UTC) — Preceding unsigned comment added by Michael.stahl (talk • contribs)

The lead is a mess
The lead is a disorganized mess, likely to put anyone off who tries to read this article. It was much better in an earlier version. I propose going back to that version (for the lead, not the whole article) and building on it. RockMagnetist (talk) 00:01, 30 November 2011 (UTC)
 * I contributed to that lede, so I figured that if I put your suggestion into play, then other editors could do their part by adding the deleted paragraphs into the body of the article. Thanks for your suggestion. --Ancheta Wis (talk) 00:37, 30 November 2011 (UTC)
 * I'm glad that someone who contributed to the lede is willing to do this. RockMagnetist (talk) 00:43, 30 November 2011 (UTC)

Suggestions for body
There is a discussion going on at WikiProject Physics and a deletion discussion for Basic concepts of quantum mechanics about how many articles should be devoted to quantum mechanics at different levels of explanation. In my opinion, multiple articles would not be needed if this one did its job better. The editors of this article should read Make technical articles understandable, particularly this rule of thumb: "Put the most understandable parts of the article up front". Then look at the first three sections of this article: 1. History 2. Mathematical formulations 3.Interactions with other scientific theories. Is this what readers are most interested in? Hardly.

Here are some of the subjects that ought to be prominently featured near the front: Do this, and there will be less call for simpler articles. RockMagnetist (talk) 01:06, 30 November 2011 (UTC)
 * the uncertainty principle
 * wave-particle duality
 * the Pauli exclusion principle
 * some interesting experiments like the photoelectric effect and the Stern-Gerlach experiment.

The history section can still lead off the article, but it should look much more like Basic concepts of quantum mechanics, with concrete examples like hydrogen spectra. RockMagnetist (talk) 01:18, 30 November 2011 (UTC)
 * I basically have a problem with 'in your face' formulations of QM. The 4 topics listed above can be derived logically from the right set of basics, just as Newtonian mechanics can be derived logically from point masses, ordinary geometry and the laws of force. Otherwise, the 4 topics are just random items which are not derivable from Newton's POV, but basically reduce down to prejudices: "Do you know A? You don't? Aha, gotcha ...". It is much more helpful to state the basic framework of the physics, and to then derive the topics as consequences. This is more useful to students, than lists of facts, for example. I admit that it is easier for an article to consist of lists of facts bagged under a name.


 * the uncertainty principle is derivable from systems with dual descriptions.
 * wave-particle duality was historically meaningful in the evolution of viewpoints from Newton, Young, Einstein, ... The thing is for physicists to be trained to be able to switch viewpoints, to get to a better representation, as needed.
 * Pauli exclusion principle, like many other 'principles' has got to be a theorem, a consequence of more basic ideas. That doesn't mean denigrate the principles, but elevate or tag them so that the hidden assumptions are exposable in the future.
 * photoelectric effect, etc. again are consequences. The issue there is experimental: what theory was just shown to be deficient by the experimental result?
 * --Ancheta Wis (talk) 04:30, 30 November 2011 (UTC)


 * Your preferred approach might be appropriate for a full-semester course on quantum mechanics, as long as the students are mathematically strong. But you can't expect to "train" students with an encyclopedia article. Anyway, even serious students usually take a series of increasingly deep courses on quantum mechanics.


 * I don't think the approach I suggest needs to be a "gotcha" approach. Look at the way Feynman does it in volume 3 of his lectures. In chapter 1 he describes a few experiments, then some basic laws of superposition and, yes, the uncertainty principle. Before he mentions the Hamiltonian, he develops the physics of bosons and fermions (and therefore the exclusion principle); emission and absorption of photons; the blackbody spectrum; and even liquid helium! In this article, the exclusion principle isn't even mentioned. RockMagnetist (talk) 05:20, 30 November 2011 (UTC)
 * And Feynman asserts that the double-slit experiment has all the elements of QM, so yes, I would have no problem with that experiment as the basis, with the other gotchas as 'Oh by the way', if you are trying to grab the reader's attention. But then there needs to be a statement of a QM framework, with Ehrenfest's theorem (the idea of gigantic averages) to show how some abstract QM framework (for example Heisenberg picture) connects with macroscopic people who live in spacetime and who use lasers, magnets, and other technology to connect with the microscopic world.  --Ancheta Wis (talk) 12:18, 30 November 2011 (UTC)
 * Certainly the framework should be there too - just later in the article. RockMagnetist (talk) 16:24, 30 November 2011 (UTC)

"Mathematical formulations" section badly needs rewriting
The first paragraph of the Mathematical formulations section is as follows:

"''In the mathematically rigorous formulation of quantum mechanics developed by Paul Dirac[9] and John von Neumann,[10] the possible states of a quantum mechanical system are represented by unit vectors (called "state vectors"). Formally, these reside in a complex separable Hilbert space (variously called the "state space" or the "associated Hilbert space" of the system) well defined up to a complex number of norm 1 (the phase factor). In other words, the possible states are points in the projective space of a Hilbert space, usually called the complex projective space. The exact nature of this Hilbert space is dependent on the system; for example, the state space for position and momentum states is the space of square-integrable functions, while the state space for the spin of a single proton is just the product of two complex planes. Each observable is represented by a maximally Hermitian (precisely: by a self-adjoint) linear operator acting on the state space. Each eigenstate of an observable corresponds to an eigenvector of the operator, and the associated eigenvalue corresponds to the value of the observable in that eigenstate. If the operator's spectrum is discrete, the observable can only attain those discrete eigenvalues.''"

This needs rewriting in so many ways.

First of all "defined up to a complex number of norm one" is meaningless unless the arithmetic operation is specified. Presumably this is multiplication.

But then, the quotient of a vector space V (over the complex numbers) by the equivalence relation that v ~ cv where c is a complex number of absolute value 1 is not "projective space". (The projective space P(V) of a vector space over a field F is the quotient space of V* by the equivalence relation v ~ cv, where v is any member of V* and c is any nonzero element of F. Here V* denotes all the nonzero vectors of V.)

Third, how about a hint as to why "the state space for position and momentum states is the space of square-integrable functions" ? (On what are they square-integrable?) Also: Does this mean the state space for the position states -- and the state space for the momentum states -- are each the space of square-integrable functions? Or is this a reference to the state space for combined position-and-momentum states?

Next, "the state space for the spin of a single proton is just the product of two complex planes" certainly doesn't appear to be defined "up to [multiplication or any other arithmetic operation by] a complex number" (of norm one or otherwise).

While "observable" has an intuitive meaning -- so perhaps it need not be defined rigorously -- the concept of an "eigenstate" of an observable has no such intuitive meaning without further explanation. So that just stating here that "Each eigenstate of an observable corresponds to an eigenvector of the operator" has no mathematical meaning. The article may as well read that "every mxyzptlk corresponds to an eigenvector" of that operator. Not. Helpful. (Or is the entire content of this statement that "eigenstate" is another word for an eigenvector of this operator?)Daqu (talk) 17:17, 25 December 2011 (UTC)

Daqu (talk) 17:17, 25 December 2011 (UTC)

Understandable?
This is one of the most un-understandable English texts in the world! Unless you have a degree in physics and English, you won't understand this article.We need an expert to rewrite it or at least the lead in a way that is understandable to more people. Arminale (talk) 14:23, 21 February 2012 (UTC)
 * OK. I copyedited a little, but QM is for a realm which is outside our ordinary experience. The objects of classical mechanics are larger than an atomic nucleus, hotter than nanoKelvin temperatures, slower than GPS satellites, and smaller than the cosmos. QM is not for your ordinary realm.
 * I have to say that it takes more than two years of study in physics to understand the one-sentence statement of QM, according to Richard Feynman, so perhaps you might clarify on this talk page just where the English prose in the lede is starting to lift off beyond the grasp of the layman. If you could do so, then we might start to add more items to the introduction to quantum mechanics. --Ancheta Wis (talk) 15:28, 21 February 2012 (UTC)

Sfngan, Thank you for the Shankar links. Could they perhaps be used in citations. Surely there is citable content for you to add. --Ancheta Wis (talk) 01:13, 4 March 2012 (UTC)

I just wanted to state that I have no physics degree, and I think that if you read the article slowly, following the links when you do not understand that actually it is quite well written. The subject itself is very complex and technical, but I think that the editors have done a pretty decent job! I am, however, a native english speaker so perhaps that is an advantage.Bob Doubles (talk) 21:42, 5 July 2012 (UTC)

Make article semi-protected?
This article is vandalized too frequently to be left open. I propose to make it semi-protected; I believe the subject/article is of enough importance to merit this. Mbenzdabest (talk) 07:30, 22 March 2012 (UTC)
 * Done. --Ancheta Wis   (talk  &#124; contribs) 09:03, 22 March 2012 (UTC)

Statement about conjugate variables needs attention
In section "Mathematical formulation", we have: "Contrary to classical mechanics, one can never make simultaneous predictions of conjugate variables, such as position and momentum, with accuracy. For instance, electrons may be considered (to a certain probability) to be located somewhere within a given region of space, but with their exact positions unknown"

1. In classical mechanics we have conjugate variables such as the time course and frequency of a signal in which precision must be traded off between the two. So the statement here is not exactly "contrary to classical mechanics".

2. The second sentence purports to illustrate the first, so should presumably involve two variables, but then discusses only one: position. Gwideman (talk) 11:47, 28 August 2012 (UTC)

New pic for template:quantum mechanics
Feedback would help here. (It's not a desperate issue, but it will affect QM related articles so I thought to notify the main article and wikiproject). Thanks, M&and;Ŝc2ħεИτlk 19:18, 4 January 2013 (UTC)

Probabilistic nature attributed to measurement?
In section "Mathematical formulations", there is a sentence: "The probabilistic nature of quantum mechanics thus stems from the act of measurement."

This seems to contradict previous paragraphs in which the need to use a probability-based description is attributed to conjugate variables.

Further suggesting there is a problem, on the Uncertainty principle page, we have: "Historically, the uncertainty principle has been confused[4][5] with a somewhat similar effect in physics, called the observer effect, which notes that measurements of certain systems cannot be made without affecting the systems. [...] it has since become clear that the uncertainty principle is inherent in the properties of all wave-like systems, and that it arises in quantum mechanics simply due to the matter wave nature of all quantum objects." Gwideman (talk) 11:55, 28 August 2012 (UTC)


 * I agree, this sentence is quirky. If I were to make such a statement, I would say "The probabilistic nature of quantum mechanics (or systems) influences the act of measurement" or possibly even the other way around. The square of the wave function (which is its only true tangible form) is a probability distribution. This does not stem from observation. If anything, observation destroys this distribution. Sean Egan (talk) 18:07, 11 September 2013 (UTC)

check out what one prof is doing with your effort
https://en.wikiversity.org/wiki//User:Guy_vandegrift/Old_Quantum_Mechanics Guy vandegrift (talk) 22:18, 11 November 2013 (UTC)
 * I followed your page, read down to the last item, a Schrödinger's cat demonstration; I tried to understand the Cleland experiment, gave up, and googled for it: Many worlds interpretation non-local realism yielded an understandable explanation, at least. Thanks for the wikiversity writeup.
 * Aaron O'Connell is the quantum experimentalist who originally built the macroscopic QM object from a silicon wafer in a laboratory clean room. He also had to build a machine to excavate the silicon which lay underneath specially designed QM object (TED talk March 2011, accessdate 2013-11-15) --Ancheta Wis    (talk  &#124; contribs) 15:12, 15 November 2013 (UTC)

Which theory has been verified to high accuracy?
The section Quantum mechanics and classical physics starts with the statement that Predictions of quantum mechanics have been verified experimentally to an extremely high degree of accuracy. This has a footnote which mentions the experimental confirmation of the electron g-factor value predicted by quantum electrodynamics (QED). What bothers me is that QED is not identical with basic quantum mechanics as formulated originally by Heisenberg and Schrodinger. Rather QED is a field theory combining quantum mechanics with special relativity, particle creation and annihilation, etc. For the g-factor as I understand it, basic spin-free quantum mechanics gives g = 1, Dirac theory gives g = 2 exactly, and QED gives the correct value near g = 2.0023. So one could say that the g-factor measurement contradicts quantum mechanics and confirms QED. Perhaps this paragraph can be rewritten to distinguish more carefully between the various theories. Dirac66 (talk) 20:37, 3 November 2013 (UTC)


 * Good points and thanks for your edits. M&and;Ŝc2ħεИτlk 08:20, 17 November 2013 (UTC)

Unification
So there's a section here on unification. A bit on M-theory and a lot on Loops. That's good. Not sure loops deserves that much attention here, but I won't complain. But... shouldn't there be something here on Georgi-Glashow SU(5)? That's the first thing I think of when I think of the absolute basics of unification. If you want I can throw a paragraph on it here. Just an idea. KagakuKyouju (talk) 07:06, 18 November 2013 (UTC)

No. This is an unnecessary addition. Arianewiki1 (talk) 05:13, 28 November 2013 (UTC)


 * Agreed that including unification isn't useful for an introductory article like this, when there are other more specialized ones. M&and;Ŝc2ħεИτlk 10:51, 28 November 2013 (UTC)

Semi-protected edit request on 17 January 2014
The following book in the further reading section is for lay people.

Cox, Brian; Forshaw, Jeff (2011). The Quantum Universe: Everything That Can Happen Does Happen. Allen Lane. ISBN 1-84614-432-9.

Would it be better if it is either removed or moved to the other section?

James (talk) 09:07, 17 January 2014 (UTC)

✅ The Notes, References, and Further reading sections are a mess. The Notes should be called References, the books in References should be included in Further reading and there should be a consistent author naming format. Unfortunately I don't know which of the books currently in "Further reading" should go into the "lay" list and which into the "technical" list. Arjayay (talk) 09:41, 17 January 2014 (UTC)
 * As a rough guide, we could say that the books which use words with very few mathematical equations are for lay people, while those books which are full of equations are more technical. I glanced at the free excerpt of Cox and Forshaw and it looks like a lay book to me. Also I have read the book by Scerri on the periodic table and I would classify it as a lay book. Dirac66 (talk) 11:51, 17 January 2014 (UTC)

Separate article on exact solutions?
Please see this section.

Any thoughts on cutting out all of the exact solutions to the non-relativistic Schro equation in this article, and merging with the content of the exact non-relativistic solutions in the Schrödinger equation article, together forming a specialized article Schrödinger equation (exact solutions) as suggested here?

Then this article (quantum mechanics) and Schrödinger equation would be shorter with less mathematics, as they link to the exact solutions article. I know that examples within context are useful, but a link to examples is just as good.

Thanks in advance. If there is no opposition, I'll go for it. M&and;Ŝc2ħεИτlk 12:47, 27 September 2013 (UTC)
 * Maschen, I support the idea. Might I request that the pictures of the exact solutions, such as particle in a well, Hydrogen atom, etc., be retained in this article, perhaps shrunk to thumbnail form? It might be noted that exact solutions are few in number. --Ancheta Wis   (talk  &#124; contribs) 21:50, 28 September 2013 (UTC)


 * A belated thanks for the only feedback on this matter, Ancheta Wis. I haven't had much chance to actually make it happen, but soon shall, given that no-one has ever objected. Yes, indeed the number of exact solutions will be few, but that doesn't stop anything. M&and;Ŝc2ħεИτlk 08:18, 17 November 2013 (UTC)


 * I just realized there is the article List of quantum-mechanical systems with analytical solutions. So no need for a new article. M&and;Ŝc2ħεИτlk 09:15, 27 January 2014 (UTC)
 * I have now added that list to the See also section of this article, which will help bring it to the attention of interested readers. Dirac66 (talk) 01:18, 28 January 2014 (UTC)


 * Thanks! Why on Earth didn't I do that myself?!? M&and;Ŝc2ħεИτlk 16:43, 28 January 2014 (UTC)

Quantum mechanics as "foundation of chemistry" (?)
This sentence is very useful as quantum mechanics, an invention residing firmly in the domain of physics, is connected to one of the other primary branches of science, chemistry.


 * "Quantum mechanics forms the foundation of chemistry by explaining the periodic table and the behavior of elements in chemical bonding, and also by providing the practical basis for countless technologies."

I have rewritten the sentence to remove some of its glaring generalizations. In particular, "forms the foundation of chemistry", "explaining the periodic table", and "countless technologies".

I think the new sentence is implicitly more constructive and accurate:
 * "Quantum mechanics provides a substantially useful framework for many features of the modern periodic table of elements including the behavior of atoms during chemical bonding and has played a significant role in the development of many modern technologies."

First, QM does not broadly form the foundation of chemistry (or, at least, many chemists would argue with this point!) Indeed, if QM were the foundation of chemistry then chemistry would logically become "physics". It is not, and frankly there are many things in chemistry that QM simply has not explained. For one -- exactly what is the physical nature of the periodic law (but this discussion is not appropriate to Wikipedia nor its talk page, so I'll move on).

Second, QM does not explain the entire periodic table. It's also, certainly not the historical foundation of the periodic table. Again, I think chemists would argue against such language, and I, as a physicist, would be on their side of that argument.

Third, "countless technologies" is simply too much to believe. Technologies are countable. I would also argue that QM doesn't necessarily provide a "practical" basis for such technologies as QM is still largely based on mathematical abstractions that exhibit consistently with real, measurable things (consider Einstein's lamentation about how QM does not get us any closer to an understanding of the "Old One" -- that is, a deeper understanding of the physical universe). The foundation of QM is the wavefunction which itself has no physical counterpart/interpretation.

Though this section on the Talk page is somewhat in the territory of being "about the topic" and not so much about the details of the page itself, I think it is a worthwhile section as we develop this Wikipedia page on a subject that is often considered the greatest invention of humankind. Some care with our language will go a long way.

Again, I strongly appreciate inclusion of this sentence, but it needed some fine tuning. TJ LaFave (talk) 02:06, 19 February 2014 (UTC)

General or special relativity?
The fourth sentence now reads It is the non-relativistic limit of quantum field theory (QFT), a theory later developed to combine quantum mechanics and relativity., with the word relativity linked to the article on General relativity. I am under the impression that QFT, or at least its earlier versions, combines QM with special relativity, and that a combination with general relativity is still somewhat elusive. If so, the sentence should really say special relativity and be linked there. Or am I confused about this? Dirac66 (talk) 03:13, 19 February 2014 (UTC)


 * It's a well-known fact that GR is not renormalizable as a QFT, still an outstanding problem. You are right that relativistic QFT is special relativity and quantum fields, nothing to do with general relativity. The sentence as it reads is wrong and not helpful in the lead, detracting from the subject of the QM of particles, so I just removed it. M&and;Ŝc2ħεИτlk 08:58, 19 February 2014 (UTC)

Most accurate?
Not any more! See the article by Penrose that says that quantum field theory has been tested to one part in $10^{11}$ while an aspect of General Relativity has been tested to one part in $10^{14}$! — Preceding unsigned comment added by RockMagnetist (talk • contribs) at 17:18, 15 January 2012
 * The article now has a citation that mentions this. YohanN7 (talk) 11:15, 7 November 2014 (UTC)

Use of lang templates within CS1 citation templates
With, Editor Coldcreation reverted my edit that removed from the title parameter in a  citation. The reason given for the reversion is not correct. Several parameters in a CS1 citation are made part of the citation's COinS metadata (those parameters are listed on all of the CS1 template documentation pages; here, for example: Template:Cite journal). The content of these parameters should be simple text. is adding non-title markup to the content of title:

when the title should be:
 * Über einen die Erzeugung und Verwandlung des Lichtes betreffenden heuristischen Gesichtspunkt

Editor Coldcreation should revert to correct this citation.

—Trappist the monk (talk) 20:04, 21 November 2014 (UTC)
 * The difference here is that in the version of Trappist the monk, the footnote for Einstein's 1905 paper showed an extra "(in German)" after the journal title (Annalen der Physik). It probably is a good idea to tell everyone what language is being used. However in this case, there is another "in German" in the same footnote after the page numbers in the reprint collection, so perhaps we don't need to tell the reader twice that the paper is in German. Dirac66 (talk) 00:47, 22 November 2014 (UTC)
 * So as I understand you both, we should dispense with both the "lang" template AND the "language" parameter. W. P. Uzer (talk) 07:59, 22 November 2014 (UTC)


 * I did not say that. The use of  within CS1 citation templates is generally inappropriate.  When the source identified by a CS1 citation does not use the English language, use of language to identify its language for readers is always appropriate.


 * The citation in question is part of a reference that is the concatenation of three separate citations, here separated:


 * My recommended change removed from title and added de in #1.  Editor Dirac66 suggests that with the addition of de to #1 the 'in German' text portion of #2 becomes redundant.  In looking at this construct, I'm not inclined to agree.  I think that #2 is an incomplete citation that should be completed and made separate.  Similarly, if #3 (also incomplete) is a 'see also' then perhaps it belongs in §Further reading.  The article would benefit from attention to cleanup §Notes which is a mix of CS1, CS2, bare urls, and non-templated citations.


 * —Trappist the monk (talk) 11:43, 22 November 2014 (UTC)
 * I think that citation as it is is fine (three possible routes to help people find what is essentially the same information); I would put the "(in German)" next to the first source, without repeating it after the reprint. W. P. Uzer (talk) 12:18, 22 November 2014 (UTC)

History, continued
The section on History might include Rado von Kovesligethy. — Preceding unsigned comment added by Wipeout10 (talk • contribs) 15:30, 30 October 2014 (UTC)
 * Thank you for your note. We need citations for the claim on his page. Nothing I see at this moment verifies the 1885 publication, or any equation showing priority. --Ancheta Wis    (talk  &#124; contribs) 18:17, 30 October 2014 (UTC)
 * See the Article in the Hungarian Wikipedia. This has "Prinzipien einer theoretischen Astrophysik auf Grund mathemateische Spektralanalyse, Wien 1884". — Preceding unsigned comment added by Wipeout10 (talk • contribs) 10:25, 31 October 2014 (UTC)
 * This is awkward. I am seeing copyright vio's in his English article. The Hungarian QM article does not list Kövesligethy Radó. I searched the Blackbody radiation article, including the history, and found no mentions of Kövesligethy Radó. The most likely place for Kövesligethy Radó's work in the English encyclopedia belongs in the discussion of black body radiators (e.g., the stars). The fact that Kövesligethy Radó derived his equation on physical grounds, thereby avoiding the Wien ultraviolet catastrophe, is classical physics, not QM. Perhaps his mention belongs elsewhere, but not in the QM page. --Ancheta Wis   (talk  &#124; contribs) 13:28, 31 October 2014 (UTC)


 * Wipeout10, a convenient way to include the links that you wish to refer to is single square brackets, for example  Wikipedia renders this external link as a blue link, followed by an arrow symbol: Your comment here
 * I should mention that external links should not be used in the text of an article, but it is certainly convenient on the talk pages, for example to state that Planck's derivation of his blackbody radiation law fit on one page (see Appendix of Planck, A Survey of Physical Theory (Dover Books on Physics))
 * You can sign your contributions with 4 tildes: --~
 * --Ancheta Wis   (talk  &#124; contribs) 14:11, 31 October 2014 (UTC)


 * As you rightly observe, the work of Kövesligethy does not fit easily into an article on quantum mechanics. If the history section of the article on Planck's law were longer with more detail, Kövesligethy would likely be mentioned, mainly for his 1890 presentation of the displacement law now named after Wien for his 1893 presentation. This is discussed by Hans Kangro in his 1976 Early History of Planck's Radiation Law. Or perhaps in an article on astronomy. By the way, Wien's work took the empirical facts into account, and so he did not have an ultraviolet catastrophe, and consequently, neither did Planck. That catastrophe belonged to pure theory.Chjoaygame (talk) 13:49, 27 November 2014 (UTC)

Lede is missing an important point
My guess is anyone with a moderate understanding of the topic will find the lede (lead) awkward, to say the least. But I'll detail some of the issues I see later. The MAJOR point I'd like to make is that made far better by the physicist/professor Matt Strassler here: [] where he states:

"There’s a risk of semantic confusion, so let’s first eliminate that.

"The term “quantum mechanics” has two uses. One is as the general category of quantum techniques, of which quantum field theory is one application. String theory would be another application. The second use is in its specific application to discrete objects that we think of as point-particles; this is what we learn first in school, for example for describing electrons in atomic physics. Let’s call that “1920s quantum mechanics” to avoid confusion. In other words, 1920s-quantum-mechanics and quantum-field-theory are both examples of the general class of things that operate according to the general principles of quantum mechanics.

"Now: 1920s quantum mechanics is inconsistent with relativity, both special and general. The only way to bring them special relativity into quantum mechanics is to use quantum field theory. So yes, 1920s quantum mechanics has to be supplanted by something more general. Doing so has many benefits, including explaining many puzzles of 1920s quantum mechanics, predicting the positron [the electron’s anti-particle], and allowing (for example) for a full quantum theory of both light and electrons, which isn’t possible in 1920s quantum mechanics. And many aspects of the world cannot be calculated successfully, or at all, using 1920s quantum mechanics, while quantum field theory does very well.

"Indeed, 1920s quantum mechanics was obsolete by the mid-to-late 1930s. (bold text is mine)

I don't believe any of this is controversial but needs to be augmented by the FACT of the continuing use of 1920-quantum mechanics with modifications (for special relativity) as the theoretical basis for Chemistry. That is, 1920-QM is still being taught and used in Chemistry. (As a chemist, I'm greatful that I didn't have to learn QFT to understand spectroscopy!!) The lede makes no mention of the two uses of the term QM, nor of the fact that 1920-QM is, aside from pedagogical uses, obsolete as the modern basis of the nature of our Universe; except, for example, what a layperson would consider chemical stuff.

Now, on to less important issues in the lede:

1. The first sentence claims that QM is a "fundamental" branch of physics. First, QM (as understood here) is obsolete and it is therefore ridiculous to claim it to be 'fundamental'. Second, it (even QFT) is known to be incomplete and has known flaws. That is: it is WRONG. Claiming that something that is wrong is 'fundamental' is really poor form. Why not use 'basic' or 'major'?

2. Second sentence:"It departs from classical mechanics..." ... DEPARTS?? Really? This is nonsense! It is a theoretical basis which rests on PROFOUNDLY DIFFERENT assumptions about the nature of the world compared to classical mechanics. I also note that the use of the term "mechanics" is a poor choice for the 98% of the audience who doesn't understand the TECHNICAL meaning of the term. "Classical physics" is a better (if less technically correct) term. This sentence is also false. There are any number of macroscopic phenomena which can only be understood via QM.

3. Sentence 3. Use of the term "dual" without explanation assumes the reader is already familiar with the concept. This is circular!

4. Sentence 4:"Quantum mechanics provides a substantially useful..." You've GOT to be kidding me! This sentence is justified in a separate Talk Page entry (which see). It is, imho, garbage. "Substantially useful...", LMFAO! I shouldn't be so blunt, but OMG how high on the autistic scale was the writer of this mumbo-jumbo? First, unless the object is to obfuscate, its a fail. Second, implying that the major contribution to chemistry is understanding the periodic table, which predicts nothing very well, is like claiming that algebra is useful for comparison shopping. My gosh, the narrowness of understanding here is breath-taking! How about...oh, say: chemical structure and bonding, reaction pathways, and spectroscopy? Apparently the author is unfamiliar with these? Wow. (note: the periodic table has NOTHING to say about the "behavior of atoms during chemcial bonding!)

5. The second paragraph is also lousy. Some behaviors are macroscopic AND extreme? As if there are no behaviors which are one, the other or neither? It is true that many macroscopic very low temperature phenom. (superconductivity, superfluidity, ...) can best be understood using QM, but so what? The next sentence is just as bad: "In the context of qm..." OK, so implicitly outside the context of QM, where is the unified view? I assume the writer failed to pass Freshman English Composition. Remove the "in the context" rubbish. Also, mention atoms and molecules, include both electromagnetics (as photons) and matter (as electrons, protons, and nuclei).

6. Next paragraph:"The mathematical formulations of QM are abstract." Oh boy...You mean that the mathematical formulation of classical mechanics is not abstract??? WRONG! Here is a hint: Any mathematical formulation is, to a lesser or greater extent, abstract. Duh! If you meant "unintuitive" (which countless texts and experts in the field (eg Feynman) will attest to), then SAY "unintuitive" and difficult to internalize. Note that this paragraph begins talking about the wave function, hence is talking about 1920-QM and not the more general field. "The wavefunction formulation treats the particle as a quantum harmonic oscillator..." HOW is this useful? How does anything QM do to the wavefunction "treat the particle"?? (I'm not asking about the QM treatment of (classical) harmonic oscillators) Again, the prose seems directed towards people who already understand the topic. Great for Schaum's Outline, terrible for an encyclopedia. The similarity between the classical mechanics treatment of waves and harmonic oscillators and the QM is apparent to anyone familiar with the former upon learning the latter, so why not just say that they are similar? With a bit more depth, perhaps...

7. Finally, the penultimate paragraph makes a "right mess", confusing the two different meanings of the term quantum mechanics. Writing on the history of the word confuses these two DIFFERENT meanings. Especially if the author is (apparently) unaware that a distinction should be made. Here Quantum mechanics as a branch of Physics has evolved into the QM used in materials science and chemistry, as well as the more accurate, more rigorous QFT used in both cosmology and the understanding of fundamental (sub-atomic) physics.Abitslow (talk) 16:59, 22 December 2014 (UTC)

thank you
@Abitslow, Thank you for your critique! We need more of this kind of viewpoint.

As for point #5, a Bose–Einstein condensate is a macroscopic QM phenomenon, a new phase of matter, at cryogenic temperature. See Eric Allin Cornell, Carl Wieman, and Wolfgang Ketterle's work. Cryogenics, lasers, computer controls, electro-mechanical setups, it's physics! OK, once the physical existence is demonstrated, maybe the physicists should let it go. ... More to come, but the encyclopedia hasn't completely hollowed out, and someone needed to reply to your much appreciated post. --Ancheta Wis   (talk  &#124; contribs) 19:34, 22 December 2014 (UTC)

Point #1: QM is 'fundamental' in the following sense: we are used to thinking about processes that occur in space and time. This viewpoint evolved from astronomy, the first science (this is the 'classical' viewpoint -- the planets are like the balls on a playground); we are used to concrete processes that we can learn from children's games on a playground (the subject of freshman physics, not abstract at all); these games build up our 'physical intuition'. Yet, QM allows us to describe processes which, when summed up, define how assemblies change with time (see Ehrenfest theorem). The Ehrenfest theorem is the sum over the Heisenberg picture of processes. There is another viewpoint, the Schrödinger picture that is more like our classical intuition. QM does not assume that its processes obey our classical intuition. Its processes make other assumptions, for example those of the Dirac equation, which yielded the prediction of anti particles (completely new physics), some of which decay in 15 minutes (like a neutron - yet we, and our chemistry are apparently stable -- we think!).

Point #2: see #1, #5 above. There aren't many exact solutions (e.g. harmonic oscillator), so we tend to get hammered by the same examples, in our talking points, over and over. More on #1: if we view the equations as models, and not as 'the way things are', it's not so important to try to internalize a field theory; it's a description, which is more or less successful, but not necessarily 'the final word'. We can rewrite it.

Point #3: I personally would have no problem rewriting sentence to show its roots in the double-slit experiment

Point #4: The QM framework is not restricted to the Schrödinger picture. We might need examples which exercise Commutator?

Point #6: See #2 about the harmonic oscillator. But as a general point, we ought not to seek certainty in science, as a final goal; it is a receding goal.

Point #7: The logical foundations of QM need a rewrite ("There is as yet no logically consistent and complete relativistic quantum field theory.", p. 4. — V. B. Berestetskii, E. M. Lifshitz, L P Pitaevskii (1971). J. B. Sykes, J. S. Bell (translators). Relativistic Quantum Theory 4, part I. Course of Theoretical Physics (Landau and Lifshitz) ISBN 0-08-016025-5). Thus we are in a fix right now. However, this is the usual state in research: "If we knew what we were doing, it wouldn't be called research, would it?" -- Albert Einstein. Perhaps we need to retreat to our roots in astronomy to find more examples, such as relativistic planets, for an observational example? Or perhaps pay attention to those research groups that are trying to build smaller accelerators instead of scaling up?

Please keep the criticisms coming everyone, including @Abitslow! Heisenberg picture has been in this article before, but it gets deleted as not introductory enough. And other editors, please add emendations to my responses, especially #4, etc. ... --Ancheta Wis   (talk  &#124; contribs) 01:20, 23 December 2014 (UTC)


 * I don't think the lede is any more awkward than any other article on a complex topic written by committee. A lot of it isn't entirely how I would have written it, but I don't think there's anything fundamentally wrong with it.


 * The first sentence makes clear that the article is about Strassler's first topic: "Quantum mechanics (QM; also known as quantum physics, or quantum theory) is a fundamental branch of physics which deals with physical phenomena at nanoscopic scales, where the action is on the order of the Planck constant." Maybe the world would be a better place if the former were always referred to as quantum theory or quantum physics, and the term quantum mechanics were reserved for point particles/electrons/atoms/what Strassler terms "1920s quantum mechanics", but that's simply not how the terms are used in the real world (or even by Strassler, whose next paragraph notes that 1920s QM is a subset of QM).Djr32 (talk) 11:11, 23 December 2014 (UTC)


 * True, usage varies. I think it good to take into account a range of sources. The term "1920s quantum mechanics" is used by Strassler, but is not standard terminology.Chjoaygame (talk) 19:08, 27 December 2014 (UTC)


 * Responding to your first few points in detail:
 * No, quantum theory is not obsolete, see above.
 * The sentence would probably be better understood as "Its predictions depart from those of classical..." rather than the its underlying physical basis (well, that's a whole other can of worms...) but this is phrasing, the sentence isn't fundamentally nonsense. You've also ignored the word "primarily" in your other criticism of this sentence.
 * "Dual" means "having two components". The phrase you object to is "dual particle-like and wave-like behavior". This is not circular at all: the behaviour has two components, like a particle and like a wave. "Wave-particle duality" is a straightforward term for a difficult concept, but it's fine to use the word "dual" in its everyday sense in a first paragraph overview.


 * Wikipedia in general is improved when people who know about these topics spend time improving the articles, rather than on giving a smackdown to the people who have already worked on them. Perhaps you could help? I know this page is semi-protected, I think you should be able to edit it yourself (I think it's just about having a sufficiently long established account) but if not then if you propose changes here then I'd be happy to transfer your updates to the article space. Djr32 (talk) 11:11, 23 December 2014 (UTC)


 * Perhaps Abitslow has used language more colourful than a stickler for propriety might like, but I think he is right to raise the topic of a regrettable general tendency of the article to fudge valid distinctions. Some changes are in order. It may be useful to air some thoughts on this page in advance of them.Chjoaygame (talk) 19:08, 27 December 2014 (UTC)

agree
There is much to agree with in the comments of @Abitslow.

The article confounds or conflates various subjects that include the word 'quantum' in their respective names. This seems more the work of Wikipolitics than of encyclopedic editing. The literature doesn't confound in that way. Most specifically, the break from the old quantum theory to quantum mechanics might even be called spectacular. Many important physical theories are valid in their ranges of applicability, but that is nowhere near high enough praise for quantum mechanics. 'Most successful theory ever' is not routinely applied as a laudatory epithet for physical theories. But it's the one for quantum mechanics. It is contrary to ordinary thinking and to the literature to regard the initial work in quantum physics by Planck and Einstein as a "version" of quantum mechanics. It is misleading for Wikipedia to make such a conflation. I have not closely studied the Wikihistory of that regrettable error, but I suppose it arose from Wikipolitical compromise rather than reasoned editing.

I am in favour of ordinary language as the preferred one for Wikipedia. Therefore I favour the phrase 'quantum physics' as a catchall for the various matters that we are concerned with. 'Quantum mechanics' is very unsuitable for replacing it. The present article regrettably does indeed try to impose that misleading replacement. I think it fair to call it an abuse of language, not what we like to see in Wikipedia.

That will do for now.Chjoaygame (talk) 10:46, 27 December 2014 (UTC)


 * Not too sure I agree with your last point. The problem with quantum physics is that it captures too much, and it is not very clear what too much means. Does it include accelerator technology and measurements apparatuses, chemistry, old quantum theory? Quantum mechanics, on the other hand, is the theoretical framework of all of quantum physics, from the late 1920:s and on, both non-relativistic and relativistic. While I have seen prominent authors argue that quantum mechanics is non-relativistic, I think that usage is rare these days. It is the same quantum mechanics that enters in non-relativistic quantum mechanics, "relativistic quantum mechanics", QFT and string theory. Relativistic quantum mechanics is usually thought of in terms of "relativistic wave equations", which surely had (and still have) their successes, but were never a full reconciliation of special relativity and quantum mechanics.YohanN7 (talk) 14:42, 27 December 2014 (UTC)


 * I think you are right to observe that the term 'quantum physics' captures much.


 * The article at present explicitly includes the old quantum theory as part of or a version of quantum mechanics. I think the article goes wrong there, putting too much into its "quantum mechanics" basket.


 * I would suggest that your "too much" is appropriate as a criticism of the present title of the article in this respect. I would say that, properly speaking, one would not say that accelerator technology is a branch or or part of quantum mechanics. Accelerator technology is largely used for the study of phenomena that are mainly treated by quantum field theory, more than by what is customarily called quantum mechanics. And I think it natural to say that accelerator technology serves quantum physics. Quantum physics is used in chemistry, but chemistry is not best described as a form of quantum physics, because non-quantum considerations,  such as thermodynamics are also part of chemistry.


 * The relativistic approach to quantum mechanics is advanced physics, and perhaps requires quantum field theory. I think quantum mechanics as it is most commonly understood is at least initially non-relativistic. I think the questions of relativity are therefore not primary in outlining the divisions of quantum physics. They are of course very important in the inner workings.Chjoaygame (talk) 18:30, 27 December 2014 (UTC)


 * Another point: One should probably be clearer about QM as a framework and the various interpretations of it. The probability amplitude interpretation of wave functions simply doesn't work with relativity (though the wave functions do have a place). Probabilities enter in other ways (most prominently as S-matrix elements) with special relativity. I know that this is stepping on many peoples toes, but let us not argue about that here (RQM would be the place for that) YohanN7 (talk) 14:42, 27 December 2014 (UTC)


 * You write "QM" and call it a framework. I agree with your usage of the term "QM". You are obviously referring primarily specifically to the more or less equivalent non-relativistic conceptual schemes of Heisenberg, Schrödinger, and Dirac. I would read you there as not intending to refer to the old quantum theory, and not to be primarily referring to quantum field theory, which are not the usual primary foci of debate about interpretation. I would say that the S-matrix belongs to quantum field theory far more than it does to quantum mechanics as usually understood.


 * QM, I think, has two more or less distinct aspects: its mathematical formalisms, and their physical meanings. How those aspects are related is subject to interpretive debate. The two aspects and their relation all belong to quantum mechanics, but do not by any means exhaust the scope of quantum physics.Chjoaygame (talk) 18:46, 27 December 2014 (UTC)


 * My usage of the term QM refers to every usage of it as a framework, and this includes when relativistic considerations are taken into account (but excludes old quantum theory). To quote Weinberg's Chapter 2 in vol. 1 of his series on QFT (this chapter is devoted to "relativistic quantum mechanics", RQM):
 * First some good news: quantum field theory is based on the same quantum mechanics that were invented by Schrödinger, Heisenberg, Pauli, Born and others...
 * My introductory book on string theory emphasizes the same point. I don't think we should not base our interpretation of the term QM on the order in which things are taught in school. YohanN7 (talk) 19:05, 27 December 2014 (UTC)

Quantum mechanics vs quantum physics vs quantum theory
This article starts "Quantum mechanics (QM; also known as quantum physics, or quantum theory) is ...". User:Abitslow's comment above raises the issue of whether these topics are really synonymous, and in parallel a new article has been started at quantum physics (which previously was a redirect to this article) which treats QM as a subset of quantum physics. Given that this article already covers quantum physics in general, I think that creating a new article for the broader topic is an undesirable content fork, so in the talk page for that article I proposed redirecting it to here: Talk:Quantum physics. However, the old redirect page probably isn't on anybody's watchlist, so I thought it would be useful to raise the question here too. To state my views plainly: What does anybody else think? Djr32 (talk) 20:39, 27 December 2014 (UTC)
 * The article on quantum physics should not be started from scratch, we already have that article here, and it's already had 13 years of work on it.
 * I don't have a strong view on what the article should be called.
 * While the new article gets something right, its valid parts worth keeping should be moved here imo. But, and this is important, it presents quantum field theory as something fundamentally different from quantum mechanics. This is unsourced nonsense! (The Weinberg quote is incorrect.) QFT is quantum mechanics, it incorporates every aspect except perhaps various interpretations of the formalism. The Hilbert space is there, the state vectors (wave functions) are there. The addition (originating in special relativity and quantum statistical mechanics where variable particle numbers are desirable) is a few more operators on the Hilbert space (creation and annihilation operators). The focus of attention is shifted from the Hilbert space to the operators on it (essentially Heisenberg picture, nothing stranger than that). The rest is just a load of mathematics and new symmetries in addition to Lorentz symmetry. Like the article, I refer to Weinberg's QFT series. YohanN7 (talk) 22:10, 27 December 2014 (UTC)
 * It seems to me that the split is undesirable, unless this distinction in terminology between QM, QPh and QTh is well-established and generally recognized among scientists. If not (and I suspect not, since apparently no-one's objected before now to calling them synonymous) then it's best to have just one article for all of them, and work on making it accurate and clear to readers. W. P. Uzer (talk) 22:36, 27 December 2014 (UTC)
 * People have indeed objected. The distinction may not be well-established. But nor is the equivalence. We should just scrap that sentence. Everybody says QM when referring to what is dealt with in this article, except for the clear-cut "old quantum theory". YohanN7 (talk) 22:52, 27 December 2014 (UTC)
 * The problem with removing that sentence is that "quantum mechanics", "quantum physics" and "quantum theory" all need to point somewhere in wikipedia, and whatever article(s) they point to really need to include the terms in the lead. Interesting to note that this topic has indeed been discussed before, with no real conclusion. Djr32 (talk) 12:51, 28 December 2014 (UTC)
 * I have discovered that. Please see below. We need to do something. YohanN7 (talk) 13:11, 28 December 2014 (UTC)
 * As to the phrases 'quantum mechanics', 'quantum physics', and 'quantum theory'. Wikipedia uses ordinary language. The phrases are obviously distinct in ordinary language. I don't wish to labour the obvious in this. If there is really only one topic here, some writers would call it by the special term of art 'quantics'. Not a widely used word of the ordinary language. I think it best to follow the usual physical version of ordinary language and accept that the phrases have distinct meanings. It is the literature that impels me to this view.Chjoaygame (talk) 02:05, 28 December 2014 (UTC)Chjoaygame (talk) 02:11, 28 December 2014 (UTC)
 * I am with you on this. Quantum theory and quantum mechanics may be close in meaning, but quantum physics definitely incorporates too much. For example, everybody agrees that QED is quantum physics. But QED, while being quantum mechanics, is a lot more than basic quantum mechanics. But is it more than quantum physics? No. I'll edit the article. YohanN7 (talk) 08:27, 28 December 2014 (UTC)

some language usages by Steven Weinberg
No single author is reliable by himself, and recency is not evidence of reliability. Steven Weinberg has been cited recently in this discussion. Here are some quotes to illustrate some of his language usage.Chjoaygame (talk) 08:39, 28 December 2014 (UTC)

Lectures on Quantum Mechanics
From Weinberg, S. (2013). Lectures on Quantum Mechanics, Cambridge University Press, Cambridge UK, ISBN 978-1-107-02872-2.

On page xvi: "I have tried in this book to avoid an overlap with the treatment of the quantum theory of fields that I presented in earlier volumes."

Searching this book for the word field, I found countless instances of it for magnetic and electric fields, but very few for quantum fields. Many of the latter were references to his other great work, in three volumes, entitled Quantum Field Theory.

On page 181 I read "In quantum field theory, it is the infinite volume of the vacuum state that allows other symmetries to be spontaneously broken."

On page 235 I read "It is not entirely trivial to formulate dynamical theories consistent with special relativity — the only really satisfactory approach is based on the quantum theory of fields — but as far as general principles are concerned, quantum mechanics applies equally to relativistic and non-relativistic systems."

On page 258 I read "But these methods fail for theories, such as quantum field theories, with unlimited numbers of particles."

On page 296 I read "In quantum field theories one would also have to represent space as a lattice of points, and integrate over fields numerically at each point in the spacetime lattice."

On page 309, at the beginning of a chapter entitled 'The quantum theory of radiation', I read "We now come back to the problem that gave rise to quantum theory at the beginning of the twentieth century—the nature of electromagnetic radiation. ... In order to quantize the electromagnetic field, we will work with a Lagrangian that leads to Maxwell’s equations."Chjoaygame (talk) 08:39, 28 December 2014 (UTC)

The Quantum Theory of Fields
I refer to Weinberg. S. (1995). The Quantum Theory of Fields, volume 1, Foundations, Cambridge University Press, Cambridge UK, ISBN 0-521-55001-7.Chjoaygame (talk) 08:45, 28 December 2014 (UTC)

Searching this book for the word field, I found countless instances of it, mostly referring to quantum fields.

On page xxi I found "The point of view of this book is that quantum field theory is the way it is because (aside from theories like string theory that have an infinite number of particle types) it is the only way to reconcile the principles of quantum mechanics (including the cluster decomposition property) with those of special relativity."

On page xxiii I found "In teaching quantum field theory, I have found that each of the two volumes of this book provides enough material for a one-year course for graduate students. I intended that this book should be accessible to students who are familiar with non-relativistic quantum mechanics and classical electrodynamics."

On page 1 I found "I have tried in this book to present the quantum theory of fields in a logical manner, emphasizing the deductive trail that ascends from the physical principles of special relativity and quantum mechanics."Chjoaygame (talk) 08:39, 28 December 2014 (UTC)

Taking quotes out of context
I recognize every single quote here. They are utterly reliable, but are taken out of context. The term "field" has, as is well-known to those who have studied the subjects classical field theory, QM 101, and QFT, different (but related) interpretations. Weinberg does not confuse them. By the way, what is your issue with "field" in the current context? YohanN7 (talk) 12:13, 28 December 2014 (UTC)


 * Steady on! Cool it! I don't have an "issue" with 'field'.


 * I just used it as search device to catch variants such as 'quantum field theory', 'quantum theory of fields'.


 * I am not "taking" the quotes anywhere. I gave the page numbers to let the reader find the context. I was just collecting evidence.


 * All I was looking for was how Weinberg uses the terms 'quantum field theory' and 'quantum mechanics'. I didn't draw conclusions. I left that to the reader. My concern is not as to the content of the quoted sentences. It is as to how they use the words. I am not questioning Weinberg's general reliability. I cited him because others did, and he is a fair candidate as a reliable source. I wasn't suggesting that Weinberg confuses or misuses any words or ideas. I think Weinberg is in general reliable in every way. But I am disclaiming that one sample from the literature is necessarily enough to solve all our problems here. Writers of books are allowed to have personal idiosyncrasies. For all I know, someone here might come up with something I haven't thought of. Perhaps someone will produce a writer who differs from Weinberg? Perhaps not?


 * For me, in the present context, a field is a function with domain three-dimensional physical space or four-dimensional physical space-time. The range is some physical entity, quantity, function, operator, whatever.Chjoaygame (talk) 13:08, 28 December 2014 (UTC)


 * A few samples from a few reliable books does solve the problem. That is, it solves the problem provided that the one who supplies the samples have read and understood the books in question. There is no question that what is at stake here, namely whether advanced theories like QFT or string theories, rely on the same quantum mechanics as that of Schrödinger, etc, or if it relies on some other type of QM, is not an issue. It is the same old QM. (I like your interpretation of "field" - anything goes. I can even source it.) YohanN7 (talk) 13:24, 28 December 2014 (UTC)


 * The long list of quotes from Weinberg was probably prompted by me noting that in his Lectures on Quantum Mechanics he devotes an entire chapter to QED ("The quantum theory of radiation"), and that this implies that he considers the term "Quantum Mechanics" to include quantum field theories, just as this article currently does. Djr32 (talk) 16:25, 28 December 2014 (UTC)


 * The quantum mechanics book gives some antecedents and some descendants of quantum mechanics. The quantum field theory books regard quantum mechanics as an antecedent or ingredient of quantum field theory.Chjoaygame (talk) 17:32, 28 December 2014 (UTC)


 * The idea did not occur to me that quantum field theory might rely on "some other type of QM". I don't see where that idea came from. I don't know of any other "type" of QM. As I read it, the range of the quantum field consists of quantum mechanical entities.Chjoaygame (talk) 17:32, 28 December 2014 (UTC)


 * The problem is not that of quoting from sources assumed in advance to be reliable. That is no problem at all. The problem is to sample and analyse the literature adequately to identify reliable sources not assumed in advance.Chjoaygame (talk) 21:17, 28 December 2014 (UTC)