Wikipedia:Peer review/Introduction to quantum mechanics/archive1

Introduction to quantum mechanics

The best article of our Category:Introduction series, this article could do with some improvement. Your comments and help are welcome. Thank you. Loom91 06:24, 5 June 2006 (UTC)

• Just skimmed so far. My first comment is that giant ugly illustration of how to do matrix multiplication really has to go. Is there a reason you can't wikilink matrix instead, then describe how matrix multiplication works in a sentence or two? -- SCZenz 06:32, 5 June 2006 (UTC)
  • I've removed that illustration. No need to explain matrix multiplication in detail in an article on QM, even that introductory. Loom91 06:34, 8 June 2006 (UTC)
• It looks really good, but isn't this the sort of things that fits better on wikibooks? It could still be linked to from the QM article. Zarniwoot 01:08, 6 June 2006 (UTC)
  • There has been AfDs on this and it was generally agreed upon that these articles should stay at Wikipedia. Loom91 06:34, 8 June 2006 (UTC)
• 100% agree with the matrix note. No reason for that to be there. --0SpinBoson 12:55, 6 June 2006 (UTC)
• Although this is a good article, this is more about the history of quantum mechanics than about an introduction to quantum mechanics.Count Iblis 14:21, 6 June 2006 (UTC)
  • Can you suggest how it can be made more as an introduction to QM? Any concepts left unexplained? Loom91 06:34, 8 June 2006 (UTC)
    • It's not so much an article about the history of quantum mechanics. Rather, it's an article about quantum mechanics that takes the historical approach to the development of the subject. That's one reasonable organization. Even so, there are some historic tidbits that seem unnecessary: link to Heisenberg's speech, comment about the first use of "eigen." And much of the material on the old quantum mechanics may be unnecessary.

One question worth answering is this: Who are the intended readers of this article? What level of interest and tolerance do they have for physics, science, and math? What vocabulary do they have? Do they know what a function is? Do they understand expressions like "on the scale of"? Can they figure out what Image:Gallery SineWave Generation.jpg means, and how it relates to the article?

Another question worth answering is this: What information about quantum mechanics belongs in an introduction? Does an introduction include phase space, relativistic quantum mechanics, entanglement? Must an introduction include both the Heisenberg and the Schrodinger descriptions? Unlike articles for magazines such as Scientific American, an encyclopedia article doesn't have use hooks like modern hot topics to grab readers' attention; instead, just present introductory topics and stop there.

Next, what level of detail is necessary? The last paragraph in the section on the reduced Planck's constant seems to talk about preferences and calculations; do we expect readers to develop a preference or perform calculations? Are the equations of the Bohr model necessary, or can they be replaced with text? Do readers need to know about matrices, phase space, eigenvectors?

So, some suggestions. First, make a clear decision about the readership, and let that guide decisions about content, vocabulary and other matters. Second, analyze each fact, development, and illustration to determine whether it's necessary in an introduction. Get out the razor and trim everything that's unnecessary.

The result can be an article that engages the readers, speaks the same language as them, and efficiently introduces them to the subject.

Fg2 20:22, 9 June 2006 (UTC)

Likewise, every historical fact should be scrutinized in light of the question of whether it helps readers understand quantum mechanics, as distinct from the question of whether it helps readers understand the historical development of quantum mechanics. If it contributes only to the historical perspective, then it belongs in a separate article, which might be named "History of the development of quantum mechanics." Fg2

Loom91, I forgot to check back here after I commented. I had another look at this article and the main quantum mechanics article. To me the main quantum mechanics article reads more like an introduction to quantum mechanics and this article is really an historic introduction to the topic. As such this article is ok.

I would suggest writing a new article on quantum mechanics that explains things in more detail. Articles on some specific topics, such as perturbation theory, WKB approximation etc. already exist, so one can write a "master article" that organizes all these smaller articles by referring to them.

Once that article is completed one can just rename the current main QM article--> Introduction to QM and this article --> Historic development of QM, or something similar. Count Iblis 21:35, 10 June 2006 (UTC)

• IMO, the target readership of this article should be those who have at least passed 12th standard or equivalent, who would already know about functions, differntial equations, matrices etc. It is a popular misconception that popular expositions on science should free from math. The reality is that science tends to get more convoluted and harder-to-understand if you try to ommit simple equaions even where they are needed. Relativistic quantum mechanics should be mentioned very briefly, including a mention of Dirac Sea which is just the sort of interesting concept for an introductory article. Entanglement is obviously a must. I agree that there is no need to give a description of Matrix mechanics. Loom91 07:00, 12 June 2006 (UTC)

So you've established that readers should know differential equations (ordinary or partial?) and matrices. What should readers be able to accomplish after reading the article? Should they be able to solve the Schrodinger equation in some circumstances? What facts should they learn? What techniques should they be able to apply? What problems should they be able to solve?

Also, the present organization of the article is historical. As I remarked, that's one reasonable way to present the material. Have you given consideration to other organizations? Do you consider the historical approach to be the best? Fg2 14:11, 12 June 2006 (UTC)

Solve Schroedinger equation??? Heck no!!! This is an encyclopedia article, not a textbook of quantum mechanics. I don't think any reader would expect to take home problem-solving skills from an encyclopedia article, let alone an introductory one. It's just something to satisfy curiosity. In any case, PDE or multivariate calculus are not covered anywhere before college. For the approach, do you think a historical approach would be best for understanding? Or something else? I don't know about this. Loom91 07:07, 13 June 2006 (UTC)

OK, readers are not expected to learn to solve the Schrodinger equation. What do you want them to learn from the article? Can you list the facts, connections, and theories that they should be able to recite, infer, and manipulate? Should they be able to calculate frequencies of hydrogen lines? If so, the equation is useful; if not, delete it? Should they learn what the Zeeman effect is? If so, develop that topic; if not, should you delete it? Should they be able to put electrons into the Bohr model? Compute wavelengths, momenta, energies of photons emitted? If so, the equations serve a purpose; if not, should they be deleted from the introduction? How much of the topic of matrix mechanics is right for an introduction, and how much should be dismissed by a simple statement such as "One method for solving quantum-mechanics problems uses matrices and is due to Heisenberg."?

Regarding organization, a historical approach is acceptable and can work. Other approaches are topical (with headers like "Computing the energy of a photon in an atomic transition"), comparative (covering things like "Experimental evidence that Newtonian mechanics does not describe electron diffraction") etc. I'm not advocating switching approaches; I'm just asking whether you'd prefer the existing one or a different one. Wikipedia articles tend to grow organically, and organization can be the result of the initial author's stream-of-consciousness outline, or a succession of accretions by independent editors; peer review is a good time to assess whether the article should stay in this form or change. If this article gets to Featured Article Candidacy, I won't oppose it for being organized on a historical basis. If you decide to keep the present organizing principle, it's fine by me.

I do think, though, that some topics should be removed or radically abbreviated. A clear delineation is necessary to distinguish introductory topics (for coverage in this article) from intermediate and advanced topics (for other articles). The presentation, including selection of equations, derivations, and examples, should be uniformly introductory in an article with the word "introduction" in its title.

"Introductory" can have various interpretations, of course. An introduction for future students of physics and chemistry will be different from an introduction for students of other sciences (for example, biology or geology), and from an introduction for non-scientists. This Wikipedia article cannot, of course, be a textbook, but if you think of textbooks that are available for students, you can imagine the first of these introductions as a textbook with a title like "A first course in quantum mechanics," rife with equations, calculations, and theoretical derivations. The third would be a sketchier, more qualitative textbook, stressing ideas over manipulations; the second, somewhere between those extremes. Which of those models best describes your intent for the article? Making that choice can make subsequent decisions easier. Fg2 14:02, 15 June 2006 (UTC)

All right, I think I'll keep the historical approach. It's a time tested approach for popular science books and I think it will work as good as any other if done properly. I think the article should stress description over analysis or manipulation since QM is such a vast topic. A few of the simpler math from old quantum mechanics can be taken, such as the Rydberg equation and its subsequent derivation from Bohr's energy formula. As for level of difficulty, a middle ground needs to be struck. Loom91 05:26, 16 June 2006 (UTC)