Deutschland – Bildungssystem

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This page has archives. Sections older than 25 days may be automatically archived by Lowercase sigmabot III when more than 5 sections are present.

I recently joined Wikipedia and my first suggested edit was to Megasonic cleaning. My guess is that this article would belong better as a subsection of the article on Ultrasonic cleaning. The help article Help:Introduction_to_talk_pages/All suggested that I draw some attention to it, since the article is a bit obscure.

Improvments in Visual Aids and Diagrams:

More illustrative diagrams to help explain the theoretical concepts and mathematical derivations. I believe that a more thorough and well-rounded article would be incredibly beneficial for students, researchers, and enthusiasts alike. If any of you have expertise in quantum mechanics or related fields, your contributions would be invaluable.

Thanks for your help! Bishopandknight (talk) 00:56, 3 August 2024 (UTC)[reply]

I guess you are referring to the Klein paradox article? I think it needs much more than a diagram. Johnjbarton (talk) 16:25, 3 August 2024 (UTC)[reply]

The whole article has to be rewritten, I do not think that even the equations are right.--ReyHahn (talk) 11:39, 5 August 2024 (UTC)[reply]

I found a good ref to start and will give it a try.

The topic is one-dimensional QM scattering from a step potential at relativistic velocity. So it's one step ;-) above simple QM, at the intersection with relativity, and is used in introductory quantum field theory examples. Seems interesting. Johnjbarton (talk) 00:24, 6 August 2024 (UTC)[reply]

Are these two topics different things?

According to Pilot wave theory it describes de Broglie's original single particle theory, not the "modern" (ie 1950's) de Broglie–Bohm theory.

• If we go with this definition about half of the article needs to be deleted. Then it would make sense to merge into de Broglie–Bohm theory as a historical section.

According to de Broglie–Bohm theory it is "also known as the pilot wave theory".

• If we go with this we should merge.

Thus I come to merge. Maybe there is a ref somewhere that clearly sets these apart in the way we do not. WDYT? Johnjbarton (talk) 16:13, 6 August 2024 (UTC)[reply]

I do not know enough to know the difference. I wonder if a merge, and a name change into Bohmian mechanics would be better.--ReyHahn (talk) 17:37, 6 August 2024 (UTC)[reply]

Maybe you are on to something, the Ngram viewer for Pilot wave theory,Bohmian mechanics,de Broglie-Bohm theory,Bohm theory agrees. Johnjbarton (talk) 02:24, 7 August 2024 (UTC)[reply]

The Queries is a subsection of Book III, Part I of Isaac Newton's Opticks it makes no clear sense that it should be its own article. The (relevant) content of the Wikipedia article for The Queries is already in the Opticks one. Both unsourced. Should The Queries redirect to Opticks? ReyHahn (talk) 17:41, 13 August 2024 (UTC)[reply]

merge A clear win. Johnjbarton (talk) 18:39, 13 August 2024 (UTC)[reply]

Redirect to the Queries section in Opticks; merge seems to not be necessary as the content is already there. Sgubaldo (talk) 00:21, 14 August 2024 (UTC)[reply]

 Done.--ReyHahn (talk) 17:21, 14 August 2024 (UTC)[reply]

Some 390-ish articles like Dirac equation use a box around special equations. The implementation, Template:Equation box 1 failed on Android in the now-default dark mode. The box was just white. I removed the background-colour feature and the equations now appear. Extra text in the box is not visible, which suggests an issue with "color" but I'll leave that as a minor issue. Johnjbarton (talk) 18:14, 15 August 2024 (UTC)[reply]

In this edit to Hubble's law @Banedon added content based on an unpublished and uncited ArXiv paper:

• Freedman, Wendy; et al. (12 August 2024). "Status Report on the Chicago-Carnegie Hubble Program (CCHP): Three Independent Astrophysical Determinations of the Hubble Constant Using the James Webb Space Telescope".

The claim added is very mild. Bandon has made the case in Talk:Hubble's law that this source should be allowed.

Since I routinely revert additions based on newly published papers let alone ArXiv preprints, I would like consensus on this exception. I would say the exception is based on the consortium of authors being a form of review, the YouTube video review, and the mild nature of the claim.

Please respond on Talk:Hubble's_law#Update_potentially_needed_for_Hubble_Tension_section?. Thanks.

(Posted to WikiProject physics and astronomy) Johnjbarton (talk) 15:09, 17 August 2024 (UTC)[reply]

We need either and article or an article sub-section on the probability four-current. Previously, probability four-current was a redirect to a subsection of the probability current article that gave the relativistic definition, but that no longer exists.

There seems to be very little good material online about this, and I'm not a specialist in the field, so I'm not going to try to do it myself. At the moment, this tutorial is the simplest treatment I can find and (just about) understand. Can anyone more knowledgeable help? — The Anome (talk) 07:45, 19 August 2024 (UTC)[reply]

I think that a subsection in probability current or in four current would be enough.--ReyHahn (talk) 11:19, 19 August 2024 (UTC)[reply]

Yes, a subsection is better. Johnjbarton (talk) 15:36, 19 August 2024 (UTC)[reply]

There have been intermittent efforts to make the publication Physics Essays look more respectable than it is. Watchlisting seems advisable. XOR'easter (talk) 18:45, 23 August 2024 (UTC)[reply]

Example at Talk:Alternatives to general relativity#Newer MOND theories? - DVdm (talk) 20:53, 26 August 2024 (UTC)[reply]

No I don't think this is related. One of the two papers is in Phys Rev Letters which has good peer review though it deliberately allows new material, eg the famous magnetic monopole. The other paper is Phys Rev D, quite staid. These are just more entries in the gravity lottery. Johnjbarton (talk) 22:30, 26 August 2024 (UTC)[reply]

A discussion is taking place as to whether the article List of important publications in geology is suitable for inclusion in Wikipedia according to Wikipedia's policies and guidelines or whether it should be deleted.

The article will be discussed at Wikipedia:Articles for deletion/List of important publications in geology (3rd nomination) until a consensus is reached, and anyone, including you, is welcome to contribute to the discussion. The nomination will explain the policies and guidelines which are of concern. The discussion focuses on high-quality evidence and our policies and guidelines.

Users may edit the article during the discussion, including to improve the article to address concerns raised in the discussion. However, do not remove the article-for-deletion notice from the top of the article until the discussion has finished.

Kevmin § 22:35, 25 August 2024 (UTC)[reply]

There is an odd article Thermal energy which, to me, seems to be a bad conflation of "true thermal" (phonons), enthalpy (probably wrt STP, but that is not defined), internal energy (also undefined in the article) and the thermodynamic state variable (with k_b). It also has too many unsourced statements, and I think some WP:SYNTH and WP:OR (or at the least not NPOV). I amrequesting comments before doing anything else, this is a high importance physics page, although it was not categorized under physics. Maybe start here, or go to that talk page. Ldm1954 (talk) 22:47, 25 August 2024 (UTC)[reply]

I avoid editing the article Thermal energy because I think it is too heavily loaded with opinion.Chjoaygame (talk) 00:31, 26 August 2024 (UTC)[reply]

Redirect to Kinetic energy. Johnjbarton (talk) 01:00, 26 August 2024 (UTC)[reply]

Kinetic energy does not discuss thermal effects, so a redirecting there would not useful. Also, the energy associated with thermal motion corresponds to kinetic energy only for simple gases.

Not sure what to do with the article though, except that I think it should be more concise. We should perhaps consider the incoming links to see what kind of article is needed. There are at least three different kinds of incoming links:

• In some cases, e.g. thermal energy storage, the meaning is associated with internal energy.
• In others, it refers to statistical distribution of constituent particle energies which is affected by temperature.
• There is perhaps also some meaning associated with thermal transport or generation of heat

Jähmefyysikko (talk) 07:03, 27 August 2024 (UTC)[reply]

Without a reliable reference that discusses specifically "thermal energy" as a type of energy we'll never succeed at an article that can pass verification. In my opinion the current article would not be accepted if offered as a create: the notability of the title is not established in the text. Logically then we should not have the article unless some can address this fundamental issue.

One random source implicitly defines thermal energy as energy proportional to .

• A. Cuadras, M. Gasulla, V. Ferrari, Thermal energy harvesting through pyroelectricity, Sensors and Actuators A: Physical, Volume 158, Issue 1, 2010, https://doi.org/10.1016/j.sna.2009.12.018.

That makes sense to me, but this is not sufficient. Something like "thermal energy" needs to be sourced to a text book. The first reference in Heat is for this lead:

• In thermodynamics, heat is the thermal energy transferred between systems due to a temperature difference.

I don't have access to the ref, but if someone does we have a solution. Johnjbarton (talk) 15:16, 27 August 2024 (UTC)[reply]

I have part done a survey of many many textbooks, mainly thermodynamics, that devote attention to heat as a major topic; I confess that there are yet more textbooks that should be included in my survey. There are two main approaches. One is that of the now obsolete caloric theory of heat, that heat is characterised in terms of temperature; this approach appeals mostly to engineers who are considering heat transport, and currently rules the lead of the article on Heat. The other is the classical thermodynamic approach that defines heat as energy in transfer by mechanisms other than thermodynamic work or transfer of matter. For some decade or so, Wikipedia's thoroughly debated editorial consensus preferred the latter. At present, I do not have the strength to try to restore it. The reason for the thermodynamic approach is partly that, in thermodynamics, absolute temperature is not defined until the second law has been stated, and that it is desirable to define heat solely in terms of the first law before stating the second law. Nowadays, the SI definition of temperature is not that of classical thermodynamics; nowadays, the SI definition of temperature is classified in thermodynamics as an empirical temperature, as distinct from the absolute thermodynamic concept. The classical thermodynamic approach has the advantage that it makes it a matter of pure logic that for a closed system, energy transfer is by either thermodynamic work or heat. It may be worth remarking that mechanical work is distinct from thermodynamic work, and that energy transfer with matter cannot be uniquely resolved into work and heat. It is also relevant that Planck (1927) gives emphasis to the production of heat by friction as an irreversible process.Chjoaygame (talk) 23:29, 27 August 2024 (UTC)[reply]

I am glad to observe that ISO 80000 distinguishes between its definition of thermodynamic temperature and its prescriptions for temperature measurements. Thermodynamics regards the latter as empirical temperatures. The definition of entropy rests on the concepts of heat and of thermodynamic work. Am I reading it aright, that ISO 80000 does not distinguish between mechanical work and thermodynamic work? Mechanical work is defined by mechanical quantities in the surrounds of the thermodynamic system. Thermodynamic work is defined by measurable state variables of the thermodynamic system.Chjoaygame (talk) 05:59, 28 August 2024 (UTC)[reply]

The source says: Heat is defined as the form of energy that is transferred across the boundary of a system at a given temperature to another system (or the surroundings) at a lower temperature by virtue of the temperature difference between the two systems. The book only contains the phrase "thermal energy" much later on page 509, where they discuss the third law, and there is a sentence Further, since the temperature is absolute zero, the thermal energy is minimum. However, "thermal energy" is not defined.

One textbook that uses the phrase heavily is Blundell & Blundell, Concepts in Thermal Physics. The book contains passages such as Heat is thermal energy in transit and ...a deficit of thermal energy given by C dT..., but they never define "thermal energy" explicitly. I think this is quite common in thermodynamics textbooks. Thermal energy is such a natural sounding concept, but no function of state quite corresponds to it on closer analysis. Jähmefyysikko (talk) 16:31, 27 August 2024 (UTC)[reply]

Here's a statement we can source ;)

The concept of thermal energy is by all odds the most obscure, the most mysterious, and the most ambiguous term employed by writers of elementary physics and by chemists. Zemansky in 'Use and misuse of the word "heat" in physics teaching' (1970) Jähmefyysikko (talk) 16:47, 27 August 2024 (UTC)[reply]

Great, I think that is the basis for reworking the article to reflect what you have uncovered so far. Don't try to give a definition, but just point to issues and examples as you have done here. To me that reflects the sources much more than what is there now. Johnjbarton (talk) 22:12, 27 August 2024 (UTC)[reply]

I more or less agree with Zemansky on this point.Chjoaygame (talk) 23:32, 27 August 2024 (UTC)[reply]

It'd be nice to clear heat of references to thermal energy. The ISO 80000 definition is authoritative: [1] fgnievinski (talk) 03:21, 28 August 2024 (UTC)[reply]

I think the Wikipedia policy of referring to established textbooks, regarded as reliable sources, is a good one.Chjoaygame (talk) 05:43, 28 August 2024 (UTC)[reply]

Hi. I am not an expert in physics, so I ask here. We have an article about Spin chain, especially about Spin-1/2 Heisenberg XXX. Some sources mention about XXZ, as in this arXiv [2]. So my question is what is that thing? What are the differences between those two? Regards. Dedhert.Jr (talk) 06:00, 27 August 2024 (UTC)[reply]

Its about symmetry. In the above arXiv paper, consider the XXZ Hamiltonian given in Eq. (2.1). The X and Y spins have the same prefactor Δ, while Z is different. For XXX all spins have the same prefactor in the Hamiltonian. Jähmefyysikko (talk) 06:18, 27 August 2024 (UTC)[reply]

Oh. I see. Dedhert.Jr (talk) 06:21, 27 August 2024 (UTC)[reply]

@Jähmefyysikko I have added this in one of polyhedral articles: triangular cupola. This is somewhat short, probably because of less background. Would you like to assist me in this case, as the technical part would like to be explicitly explained for non-science audience? Dedhert.Jr (talk) 06:39, 27 August 2024 (UTC)[reply]

Hi, sorry but I don't think we should add this to the cupola article unless there is some very special property that only occurs there. The games theoretical physicist play with various geometries is not something we need to cover in an encyclopedia. Jähmefyysikko (talk) 07:08, 27 August 2024 (UTC)[reply]

It has been shown that the atomic wavefunction traversing the Stern-Gerlach magnet immediately collapses to one spin eigenfunction when a field quantum is absorbed by the atom. (See the "Importance" section of the S-G page.) This contradicts almost a hundred years of mistaken explanation in our textbooks and research papers.

I've discovered that a remarkably simple, and practical experiment can now corroborate that understanding (Published in the J. of Physics B very recently (Devereux, 2024, https://doi.org/10.1088/1361-6455/ad5992). There is much resistance to such a new understanding, and its confirmatory observation, from researchers who have uncritically accepted the received explanation. I'm asking for acceptance from the community here that I be allowed to edit the "Importance" section of the S-G page to include a citation to that recent J. Phys. B article. The J. Phys. B publication lacks some of the criteria for an immediate reedit to Wikipedia: just one author, and no citations to that article yet. Still, I would like to make that edit now because of the critical importance to quantum measurement and Q.M. foundations of realistically describing the S-G experiment. D bar x (talk) 21:45, 28 August 2024 (UTC)[reply]

If the result is as fine as you say it is it will soon received hundreds of citations in the scientific literature. That will determine if it is notable enough for Wikipedia. As far as I can see the paper has received zero citations so far. Wikipedia follows but does not lead. Xxanthippe (talk) 00:58, 29 August 2024 (UTC).[reply]

Just for visibility, my explanation for reverting the edit is on the Quantum superposition Talk page. Johnjbarton (talk) 04:31, 29 August 2024 (UTC)[reply]

Could I have extra eyes at Mean radius/Talk:Mean radius. There's a dispute about whether or not certain things are mean/effective diameters/radii, and providing sources (or common sense) doesn't seem to help. Headbomb {t · c · p · b} 00:53, 29 August 2024 (UTC)[reply]