Wikipedia talk:WikiProject Physics

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Fock's sphere in theory of hydrogen atom

Hello, the new article Fock's sphere in theory of hydrogen atom appears (to my non-physicist's eye) to be a rewrite of Fock symmetry in theory of hydrogen. This was discussed and redirected a year ago, following discussion at Wikipedia_talk:WikiProject_Physics/Archive_August_2021#Fock_symmetry_in_theory_of_hydrogen. If this new article is a rewrite, then is it better than the original? Can and should the two be merged? Thanks, Storchy (talk) 10:19, 9 November 2022 (UTC)

It has now been moved to draft space. It was created by a known self-promoter. And to my inexpert eye, it adds nothing but a sort of oo-ah tone that does not belong in WP. What Fock symmetry redirects to seems to me to be more complete and considerably more understandable. IMO, it should have been deleted. —Quondum 12:58, 9 November 2022 (UTC)

Thanks. Just noticed their sandbox, which clarifies how the "new" version is simply minor tweaks of the old [1]. Storchy (talk) 13:31, 9 November 2022 (UTC)

Should my user page be deleted?

Again someone is trying to delete my user page. If you have an opinion on that, please express it at Wikipedia:Miscellany for deletion/User:JRSpriggs (2nd nomination). JRSpriggs (talk) 02:43, 10 November 2022 (UTC)

Closed as snow keep. Thanks for your support. JRSpriggs (talk) 01:41, 12 November 2022 (UTC)

Proton radius puzzle on Muon page

I don't know all the details of the papers on this topic, but this section of the page about the muon should at least be updated to reflect the details given at Proton_radius_puzzle. It currently only goes cites things to 2015, and quite a bit has changed since then. The Proton_radius_puzzle also feels out of date, being phrased as if this is still a significant issue, whereas I believe it's mostly resolved as of ~2020. - Parejkoj (talk) 08:38, 11 November 2022 (UTC)

I significantly shortened this section and merged it with the previous one. Ruslik_Zero 20:20, 15 November 2022 (UTC)

AfD: Gravitational coupling constant

At Wikipedia:Articles for deletion/Gravitational coupling constant —Quondum 18:42, 15 November 2022 (UTC)

ANI about a pseudoscientific theory of gravity

This was an interesting discussion at ANI: Wikipedia:Administrators'_noticeboard/Incidents#Persistent_posting_of_original_research_and_pointless_chat_at_Talk:Gravity. –LaundryPizza03 (dc̄) 02:31, 16 November 2022 (UTC)

Add ronna- and quetta- to units articles?

Should we add today's four new SI prefixes (quecto-, ronto-, ronna- and quetta-) to our various articles on units of measurement? For example, Tonne now lists ronnatonne and quettatonne with their equivalents. I recently reverted the addition[2] of a table ranging from quectocandela to quettacandela, calling them fantasy units and a waste of our readers' attention, but now regarding Tonne, {{Quantities of bytes}} and others, I'm told[3] we should include the prefixes even if no-one uses them, and now I'd be glad to see some consensus either way. NebY (talk) 23:13, 18 November 2022 (UTC)

OK, now they're just messing with us. --Trovatore (talk) 19:31, 19 November 2022 (UTC)

There is an obvious and clear precedent for including all prefixed forms of a unit in tables: most of the "yotta-" prefixes. Nobody uses yottametres, at that scale it's light-years/parsecs/redshifts. Nobody uses yottagrams, at that scale it's probably Earth masses. Yet metre and kilogram have and have long had them listed in neat little tables. Quondum added the new prefixes immediately to {{SI multiples}}, and the new "ronna-" and "quetta-" forms were added to {{Quantities of bytes}} by three separate editors: myself, Dondervogel 2, and Anthonyryan1. They were added to Tonne by myself and I am a Green Bee. The consensus NebY seeks is present and obvious: it is in favour of adding the prefixes in question. Double sharp (talk) 23:18, 18 November 2022 (UTC)

For information: {{SI multiples}} is used[4] in 11 units articles and 5 orders-of-magnitude articles to make tables listing units from eg quectoampere to quettaampere. NebY (talk) 23:35, 18 November 2022 (UTC)

I echo Double sharp here: in terms of tables, these should be complete where the article lists prefixed units for official (i.e. SI) cases. Tonne is not an SI unit; that table could be trimmed after megatonne. Candela is an example where one might not include a table at all. The purpose of an encyclopedia is to (reliably) inform – in this case, about the existence of the SI units, which includes all prefixed forms – not to present only what is familiar or common. Relatable examples include the electron mass of 0.9 rontograms and Jupiter at 2 quettagrams. One motivation of the prefixes was to get ahead of the existing very real trend of invention of ad-hoc prefixes (hella-, bronto-, ...), which shows that they are of interest to the average joe. —Quondum 00:23, 19 November 2022 (UTC)

I think gigatonnes are common enough to include, but yes, agreed on cutting the table early for tonnes. Double sharp (talk) 01:21, 19 November 2022 (UTC)

Done. Google ngram (only one result for "teratonne", none for "petatonne"). —Quondum 01:49, 19 November 2022 (UTC)

@Quondum: thank you for doing that and resolving one of the contentions. I'm glad you mention Candela as an article where might not have a table. Do you think the underlying principle might be that the four SI units that have physiological weighting factors (candela, lumen, lux and sievert) are only used within comparatively narrow ranges? In my experience their use is roughly bounded by physiological relevance, after all. NebY (talk) 15:52, 19 November 2022 (UTC)

I agree with that thought. There is no conceivable use for quettacandelas, even in principle.--Srleffler (talk) 23:26, 19 November 2022 (UTC)

My suggested rule of thumb here is based on the presence or absence of "yotta", as I've never actually seen it used in practice. If it already isn't there, then there's clearly a precedent that a complete set is not needed. But if it already is there, then there's a clear precedent to show a complete set. Double sharp (talk) 00:24, 20 November 2022 (UTC)

NebY, I'd go along with that (say 10–15 orders of magnitude). I'm not an expert, though. —Quondum 02:42, 20 November 2022 (UTC)

This is a long-winded concurrence with keeping all prefixes on official SI units and trimming to in-use cases for other units. My opinion is that the extreme units are merely distracting when they are so rarely used that they would be viewed as cheeky or intentionally obscure even in a scientific or technical publication. Writing that the electron mass is 0.9 rg or that Andromeda Galaxy is 24 Zm away is distracting and not done in practice without further explanation, not even written out as rontograms or zettameters, and readers should be given a clue that this is the case. The use of bold to imply what's not common practice is extremely helpful, so I'll keep my complaints about rare prefixes to a murmur. Any reason not to use this bolding method in metre and second? For other-than-base units, it does the job to show commonly used cases and point out that all the SI prefixes are technically allowed.

Also, unless someone persuades me it's not helpful, I suggest adding SI units to the many articles that lack them, as we come across them, along with the conventional units like light-years. For example, the distance to Sirius is at present given only in parsecs and light-years, with 8.1×10¹⁶ m left as homework. This makes comparison difficult, e.g. comparing to the distance to the Sun.

On the lighter side, see this xkcd essay for a bit of fun with extremes of luminous intensity. –MadeOfAtoms (talk) 09:51, 20 November 2022 (UTC)

I by "common practice" guess you mean "familiar to the man in the street", and sure, "commonly used units" could be bolded in Metre and Second. Judging what is obscure in scientific circles is trickier. Combination units can use prefixed units that do not normally occur standalone. For example, despite the elementary charge being 160 zC (no direct use for yC or below), the non-SI D might (I guess) over time be replaced by the similarly sized qC·m because this is now conveniently sized as a unit of electric dipole moment of particles or atoms. We can't readily judge what is "strange" if used in scientific literature. The only real value I see in a table is: it allows quick visual relative placement, and it familiarizes the eye to the combinations (e.g., when I see something unfamiliar like 'mT', I might not immediately recognize even what sort of unit it.) In this context and use, including all makes sense, even though the last few might be very obscure. It also has value in introducing people to the new prefixes. —Quondum 15:33, 20 November 2022 (UTC)

@MadeOfAtoms: I fear that if you started adding metre distances to stars and galaxies, you'd find yourself sharply reverted. Once we appreciate that even Sirius is hundreds of thousands times more distant than the sun, light-year and parsec are more useful for describing and differentiating between stars, and are the conventional units. You'd be going against the documentation and functionality of the infobox too, but perhaps more importantly you'd be spending that most important resource, the attention of our readers. NebY (talk) 16:27, 20 November 2022 (UTC)

I'm with MadeOfAtoms (talk · contribs) on this. Seeing some distances in light-years, some in parsecs and some in astronomical units is confusing. A conversion to SI units would be helpful. Dondervogel 2 (talk) 20:49, 20 November 2022 (UTC)

I'd say that making distances more comparable is off-topic for this thread (though not necessarily without merit). —Quondum 21:31, 20 November 2022 (UTC)

@Quondum: By "common practice" I don't have a precise meaning in mind, but how reliable sources use each unit is a verifiable approach. "Common" will always be open to judgement and have grey areas, and combination units do make it trickier. A solution like the common units in bold in kilogram multiples seems like an excellent one to use for more unit articles. Kilogram specifies criteria for inclusion as "common", whose details can then be a separate discussion if anyone disagrees. Regarding SI units added pervasively: thanks NebY for the convincing advice. Even though the ideal of specifying a common unit is attractive to many like me and Dondervogel 2, I'll leave it to the reliable sources and the most focused editors of each article to select the most helpful set of units. If there's much more to say, let's start a new thread per Quondum's note. –MadeOfAtoms (talk) 00:14, 21 November 2022 (UTC)

I don't see the harm in documenting them in areas specific to SI units. However, I think it's far too early to use them in articles outside of that. We should, as always, follow our sources. If our sources are using parsecs, light-years and so on, then our articles should respect that choice of unit. This is, functionally, almost the same thing that's been going on with WP:COMPUNITS (and the attempts to force "gibibytes", "mebibytes", et al. into articles where the sources have never or very rarely use those terms). —Locke Cole • t • c 19:53, 21 November 2022 (UTC)

I never said we should actually use those units. We don't use any of the yotta- units either, because even though that prefix was adopted in 1991, those units are not used in practice. I merely claim that any case where they are mentioned is a precedent for adding the ronna- and quetta- units which are in the same situation. Double sharp (talk) 20:05, 21 November 2022 (UTC)

That seems perilously close to the common argument that if we've included fact A we should also include much more recondite fact B (re which the editor happens to be a fan), or more generally that however far we've stretched, we should stretch further. "Yottabyte" itself is very rare - a company name, a storage architecture that could scale to yottabytes but never has - and hardly makes the case for going further. It's not as if bits and bytes pass Quondum's test of being SI units either, not even being listed in the SI Brchure as Non-SI units that are accepted for use with the SI. NebY (talk) 16:31, 22 November 2022 (UTC)

If byte multiples are cited by BIPM as the raison d'être for the existence of the new prefixes, that alone seems reason enough to extend the byte template to include them. Dondervogel 2 (talk) 16:42, 22 November 2022 (UTC)

Did the BIPM refer to bytes, and did it refer to bits? NebY (talk) 17:18, 22 November 2022 (UTC)

The news release at Nature.com is entitled How many yottabytes in a quettabyte? Extreme numbers get new names and includes the words "Today, the driver is data science, says Richard Brown, a metrologist at the UK National Physical Laboratory in Teddington. He has been working on plans to introduce the latest prefixes for five years, and presented the proposal to the CGPM on 17 November. With the annual volume of data generated globally having already hit zettabytes, informal suggestions for 10²⁷ — including ‘hella’ and ‘bronto’ — were starting to take hold, he says. Google’s unit converter, for example, already tells users that 1,000 yottabytes is 1 hellabyte, and at least one UK government website quotes brontobyte as the correct term" Dondervogel 2 (talk) 19:36, 22 November 2022 (UTC)

Thanks. From that article we have

- annual total world byte generation set to reach 1 yottabyte in the 2030s

- new prefixes for 1,000 and 1,000,000 times that only named to stop other names

- no use case for the new little-end prefixes

- no mention of bits

- entire Latin alphabet consumed, so no more new prefixes ever.

That's a relief, we don't need to worry about unlimited expansion of the tables, but all in all it makes

- some case for expanding the byte article

- a much weaker case for expanding byte templates, adding unused stuff to various articles, the MOS etc

- not much case at all for expanding bit templates. NebY (talk) 21:05, 22 November 2022 (UTC)

• The case for expanding the byte template seems every bit as strong as the case for expanding the byte article. I don't understand the argument for expanding one and not the other.
• I've seen the terms ronnabit and quettabit used in foreign language articles, but not yet in English. Nevertheless, once prefixes are defined by the BIPM they are applicable to all units of the International System of Quantities, including the bit and the byte. So while I accept the case for expanding the bit template is weaker than that for byte, it remains a strong case.

Dondervogel 2 (talk) 21:26, 22 November 2022 (UTC)

A BIPM document by the proposer of the new prefixes (Richard J. C. Brown) indeed notes that there wasn't any driver for the small-end prefixes, and that they were only included because it was considered foolish and unbalanced to only extend the range at one end. It explicitly mentions that bits and bytes are the main driver for the large-end prefixes: The main pressure for new SI prefixes comes currently from outside the SI, from information technology and data storage; in particular from ‘units’ for describing digital information and data size, such as ‘bit’, ‘byte’ and ‘octet’. ... Given the accelerating growth of data production rates and data storage requirements this field will soon require prefixes to cover orders of magnitude in excess of yottabytes. The popular scientific literature is already speculating on what these might be. In New Scientist, Brown suggests that ronto- and quecto- would make sense in radio astronomy, where such scales are needed, but a physicist (Mike Merrifield) points out that most astronomers just use janskys instead. But that's not relevant to the question of the byte and bit articles and tables, where none of the negative-power prefixes were included to begin with, and none were proposed for inclusion. This document says that the letter "B" is the last available, yielding one more potential prefix pair, but that might've changed since in the more recent Nature article Dondervogel 2 linked, Brown notes that B is also unavailable. Double sharp (talk) 21:35, 22 November 2022 (UTC)

I can't see what the aversion to a few items in a table is. If the table lists the prefixed forms, why leave off the last two? I see an irrational aversion to embracing change in so many places. To put things in perspective: the CGPM "owns" (is the defining authority for) some non-metric symbols such as tonne, dalton, day, but has not said which prefixed forms of these are valid (except that minute, hour and day may not be prefixed), and it is not for us to synthesize these forms. It does not "own" the byte or bit, but other bodies such as the IEC do lay down standards for these. If the IEC has said that nonfractional metric prefixes (in general) apply to the byte (which would need checking), then this includes ronna and quetta, and we should include these in any table as per Double sharp's rule of thumb. As far at the templates for binary prefixes are concerned, most who value their sanity have learned to steer clear of them. No debate around them is likely to be balanced. —Quondum 03:48, 23 November 2022 (UTC)

AFAICS nobody is proposing to add the obvious analogous binary prefixes robi- and quebi- to tables. They have been mentioned as the natural analogues in a consultation paper, but have not been adopted by the relevant authority for those prefixes. I did put in a brief cited mention at Byte to explain that situation, but left them out of the table precisely because they haven't been adopted. Double sharp (talk) 08:27, 23 November 2022 (UTC)

For the record, there was one good faith attempt to extend the binary prefixes, but it was reverted. Dondervogel 2 (talk) 09:14, 23 November 2022 (UTC)

OK, thanks. I stand corrected: AFAICS there is no consensus to add the obvious analogous binary prefixes robi- and quebi- to tables, whereas there is for the decimal prefixes ronna- and quetta- in cases where yotta- is already there. Double sharp (talk) 11:17, 23 November 2022 (UTC)

Surely the reason not to add these is because the IEC hasn't defined them yet? Barnards.tar.gz (talk) 11:16, 24 November 2022 (UTC)

Correct. That is the reason there is no consensus for adding them. Dondervogel 2 (talk) 11:23, 24 November 2022 (UTC)

I see the templates as providing handy guides in articles/MOS/etc to help readers understand text in those articles/MOS/etc. Handy guides that relate to what we might be reading are better than ones that also tell us about things that aren't actually to be found in use in our articles or elsewhere. As for disliking change, changes in templates aren't detectable on article/MOS watchlists so template editing carries an extra layer of responsibility, though minor in these cases compared to some. NebY (talk) 18:40, 23 November 2022 (UTC)

The templates have long included the yotta- forms that do not have any actual use. (Unsurprisingly, as that prefix was adopted before WP even existed.) It would seem quite clear from the evidence that how you see the templates is inconsistent with how they have long been actually used. Double sharp (talk) 22:49, 23 November 2022 (UTC)

OK, Double sharp, I'm not convinced but I'm happy to say no more about extension of the bit & byte templates. I'm only back because Litre just popped up on my watchlist. Its table has gained quectolitre, rontolitre, ronnalitre and quettalitre, with equivalences from thousand cubic picometres to cubic gigametre.[5] It already went from yoctolitre to yottalitre. Does that settle it or should we take the same approach to that as you and Quondum did to tonne? NebY (talk) 18:06, 28 November 2022 (UTC)

@NebY: There are actual uses of the extreme small prefixes with the litre, e.g. femtolitre, attolitre, zeptolitre, yoctolitre. So, even though litre is a non-SI unit accepted for SI use (like tonne), there seems to be enough of a case to keep the whole set. (The large prefixes appear to be uncommon, but it seems sensible to show a symmetrical range.) Double sharp (talk) 18:31, 28 November 2022 (UTC)

Thanks for those. "1 yL can contain ~100 metal atoms..." I am awestruck. I haven't tried to figure what a quectolitre might contain, but that is simply beautiful. NebY (talk) 18:47, 28 November 2022 (UTC)

The table does not need two sides; it can be presented as a single range running from something small up to around gigalitre. It is already too wide. This sort of nixes the symmetry argument. —Quondum 18:50, 28 November 2022 (UTC)

What an improvement! A straightforward sequence is so much more readable than a symmetry of powers. NebY (talk) 19:53, 28 November 2022 (UTC)

@NebY: Metals are nowhere near the smallest atoms. Helium is one of the smallest atoms, and its atomic radius is 31 pm. Plugging that into the formula for the volume of a sphere, we get the volume of a helium atom as 1.25 × 10⁻²⁸ litres, which gives a sensible use for quectolitres. Naturally, an alpha particle (helium nucleus) will have even smaller volume. Double sharp (talk) 19:00, 28 November 2022 (UTC)

FWIW, I would limit Litre to 18 orders of magnitude, from nL to GL. I understand you *can* go further but don't see a strong case for it, because use is so rare. The same logic applies to Tonne (nt to Gt). Dondervogel 2 (talk) 19:14, 28 November 2022 (UTC)

Quetta sounds cool! I am a Green Bee (talk) 10:35, 19 November 2022 (UTC)

Roche limit

This article is a mess, and has accumulated lots of garbage since the FA demotion in 2007.

• The mathematical description needs to be condensed by removing unnecessary derivation and textbook-like language.
• There are loads of unsourced content with plenty of likely OR; some of the citations should be inline for clarity and to prevent the article from attracting further OR.
• I recently removed a section consisting only of data tables based on unsourced and often conjectural data; and an incoherent section connecting the topic to the Hill sphere, that was also severely damaged during an attempted copyedit in January 2021.

–LaundryPizza03 (dc̄) 08:35, 19 November 2022 (UTC)

Slip bands

We have an article titled Slip bands, which is terrible, and doesn't even define what they are. We also have an article titled Lüders band, which is much shorter, but is better written.

Are these the same thing? Should they be merged? Is there a difference? This is WAY out of my area of expertise, and I'm having trouble even making a dent in trying to wrap my head around the topic. PianoDan (talk) 17:32, 21 November 2022 (UTC)

Policies on academic notability/mathematical OR?

Hi, I cannot seem to find any notability guidelines on academic subjects (as opposed to academics). A highly technical subject would be unlikely to meeet WP:N because nobody writes articles about, say, Gibbs free energy, but it is certainly a notable subject; on the other hand, applying WP:N to sources such as textbooks also doesn't quite work (something mentioned across several well-renowed but specialised textbooks, such as Method of virtual quanta, is clearly non-notable). There does not seem to be a clear equivalence that can be drawn from the existing policy. Is there any separate consensus to this matter (and if so is there a place where people can look it up)? Sorry if I'm butting into a discussion that's been had thousands of times.

Separate issue - a lot of physics or mathematics articles have sections of derivations or calculations marked with original research tags. While in many cases it would be possible to find a textbook in which the exact derivation is repeated, it should probably not be necessary to do so (as anyone who understands the derivation would be able to verify it). Is there any consensus as to the threshold for this either? Fermiboson (talk) 21:48, 21 November 2022 (UTC)

@Fermiboson, notable in the Wikipedia sense means already well-known as shown by the existence of multiple in-depth sources from reliable publishers independent of the originators of the topic. Specialized textbooks are fine. See Wikipedia:Identifying reliable sources (science). We don't expect academic topics to use sources from the popular press.

On the other issue, much of the core content of our scientific and technical articles was added before Wikipedia articles required sources. In fact material in textbooks was thought not to require sources in our articles because it was already in textbooks. We now recognize the need for sources in part because of the difficulties raised at scientific articles. People wanted to add their own theories of relativity or ideas about quasars. Current policy requires sources, including for derivations. We encourage adding sources to existing material in articles. StarryGrandma (talk) 22:15, 21 November 2022 (UTC)

Thank you for the clarification. Fermiboson (talk) 22:25, 21 November 2022 (UTC)

Inconsistencies related to mechanical energy

The following paragraph was inserted at Conservation law#Approximate laws on November 13. (See the diff.)

There are also conservation laws which appear approximate, but only because microscopic details are neglected. For instance, the conservation of mechanical energy was often considered to be non-exact because forces such as friction appear to convert mechanical energy into other forms. However, a close inspection of friction reveals that only conservative forces are involved (electromagnetic forces), and the heat energy produced by friction is actually mechanical in nature (in the form of kinetic and potential energy). In this manner, it was realized that mechanical energy, as defined as the sum of kinetic and potential energies, is in fact fully conserved in all circumstances. It is only macroscopic energy which is not. Source: The Feynman Lectures on Physics

This text was posted in one of a number of recent edits by Logic314. (Logic314 has attributed the edits to the Feynman Lectures on Physics, Volume 1. I don’t have a copy.) This paragraph is inconsistent with a number of Wikipedia articles that have Top importance on the project’s importance scale. Here are five examples:

In Mechanical energy Wikipedia says "The principle of conservation of mechanical energy states that if an isolated system is subject only to conservative forces then the mechanical energy is constant." In contrast, in the new paragraph quoted above, Wikipedia now says “In this manner, it was realized that mechanical energy, as defined as the sum of kinetic and potential energies, is in fact fully conserved in all circumstances”.

In Conservative force Wikipedia says the total work done by a conservative force in moving a particle between two points is independent of the path taken; Wikipedia also says frictional force is an example of a non-conservative force. In contrast, in the new paragraph quoted above, Wikipedia now says “a close inspection of friction reveals that only conservative forces are involved (electromagnetic forces), and the heat energy produced by friction is actually mechanical in nature (in the form of kinetic and potential energy). ... mechanical energy ... is in fact fully conserved in all circumstances ...“

In Friction Wikipedia says “Friction is a non-conservative force – work done against friction is path dependent. In the presence of friction, some kinetic energy is always transformed to thermal energy, so mechanical energy is not conserved.” In contrast, in the new paragraph quoted above, Wikipedia now says “forces such as friction appear to convert mechanical energy into other forms. However, a close inspection of friction reveals that only conservative forces are involved (electromagnetic forces), and the heat energy produced by friction is actually mechanical in nature (in the form of kinetic and potential energy). ... mechanical energy ... is in fact fully conserved in all circumstances ...“

In Inelastic collision Wikipedia says “An inelastic collision, in contrast to an elastic collision, is a collision in which kinetic energy is not conserved due to the action of internal friction.” In contrast, in the new paragraph quoted above, Wikipedia now says “a close inspection of friction reveals that only conservative forces are involved”. The implication appears to be that all collisions are elastic because mechanical energy is always conserved.

In First law of thermodynamics Wikipedia explains that when a body absorbs sensible heat or latent heat, its internal energy increases, regardless of whether the source of the heat is friction, combustion, electric current etc. In contrast, in the new paragraph quoted above, Wikipedia now implies that when a body absorbs heat generated by friction, its microscopic mechanical energy increases to match the reduction in macroscopic mechanical energy so that mechanical energy is conserved. Logic314 has not mentioned internal energy so it is unclear to me how Feynman describes the energy absorbed by a body as a result of combustion or an electric current. The first law of thermodynamics is intimately connected to the concept of internal energy.

Logic314 appears to believe their edits represent a profound change to Wikipedia’s coverage of the subject, and Feynman’s view on this matter is an amazing discovery. I disagree because Logic314’s edits merely alter the definition of the mechanical energy of a body so that, as well as macroscopic kinetic and potential energies, it also includes sufficient of the body’s internal energy that mechanical energy is conserved even in the presence of friction, and therefore friction can be declared a conservative force. Logic314’s law of conservation of mechanical energy is little different to Wikipedia’s law of conservation of energy. Logic 314 has conceded that point because they have written “When everything is considered, conservation of mechanical energy is a complete exact conservation law, and is in fact equivalent to the full conservation of energy”. See Logic314’s diff.

The limited applicability of the principle of conservation of mechanical energy plays an important role in mechanics, particularly for students. It is important for students to realize that conservation of mechanical energy is a principle that is very easily applied quantitatively, but it is only applicable when all forces are conservative. When a non-conservative force is at work, we must rely on conservation of Momentum which is usually the next topic to be studied. Students are entitled to ask "If mechanical energy is always conserved, why do we need conservation of momentum?"

I have challenged some of the edits made by Logic314. See my diff 1 and diff 2. In particular, see Logic314's explanation at Talk:Conservation law#Conservation of mechanical energy. Logic314 has not returned to this topic for more than a week so I am raising the matter for consideration by the Physics community.

The question for the Physics community is What should be done about the inconsistencies introduced by Logic314’s edits at Conservation law?

1. Should we ignore the inconsistencies?
2. Should we establish a project to adjust other articles such as Mechanical energy, Conservative force, Friction, First law of thermodynamics to make them consistent with Feynman and Logic314’s recent edits?
3. Should we adjust the text posted by Logic314 to make it an alternative viewpoint about conservation laws rather than the one-and-only explanation of conservation of mechanical energy, thereby giving it due weight but not undue weight?
4. Should we revert Logic314's edits at Conservation law? Dolphin (t) 02:55, 22 November 2022 (UTC)

Disregarding sources for now, from a physicist's standpoint the theories you apply depend on the context. On a human scale, conservation of mechanical energy is approximately true (or sometimes even just not true at all). At the atomic/subatomic level, as Logic314 points out, conservation of mechanical energy holds true since mechanical energy is redefined to include all energy. Therefore, on articles where "mechanical energy" is defined as ${\frac {1}{2}}mv^{2}+V({\overrightarrow {r}})$, the law holds approximately true no questions asked. On articles where "mechanical energy" is defined as $<\psi |{\hat {H}}|\psi >$ then yes, the law is absolute.

To answer your question then using this framework - the article mechanical energy should be kept as is, especially as the article has an entire section named "conversion". Friction is explicitly about the macroscopic phenomenon and hence should also be kept as is. The first law of thermodynamics relies on the concept of temperature (hence heat energy) as separate from mechanical work, hence it should also be kept as is. Conservative force is a bit more iffy, because it's hard to say if you can even define a force at the relevant scale.

Overall, therefore, I suggest we modify Logic314's original version to make it clear that there are two different definitions of mechanical energy being operated under (and I believe Feynman does make it clear that he doesn't mean all energy when he talks about mechanical energy in anywhere else but the relevant semantic curiosity). @Logic314 Fermiboson (talk) 18:47, 22 November 2022 (UTC)

If you define "mechanical energy" so broadly as to encompass everything including relativistic mass-energy, then the conservation of "mechanical energy" is as exact as the conservation of energy. I don't think that's a particularly profound statement. What matters is explaining the concepts (heat is the jiggling of molecules, etc.), not the presence or absence of a particular adjective on a certain page of a specific book. I think that most instances of "mechanical energy" in physics writing would mean "the kinetic and potential energy of macroscopic bodies due to their bulk behavior", i.e., not including heat, chemical bonding, etc. My impression of introductory thermodynamics texts is that they contrast "heat" and "work" or "mechanical work". But that's not a hard-and-fast rule by any means. XOR'easter (talk) 21:09, 3 December 2022 (UTC)

@Fermiboson, Caltech has kindly put the Feynman Lectures online. Section 14-4 of Volume I is titled "Nonconservative forces" (Section 14-3 is "Conservative forces"), and doesn't mention "mechanical energy" at all, or refer to "macroscopic" energy. The conclusions in the paragraph added above are the conclusions of the editor, not Feynman. I think the edit could be reverted. StarryGrandma (talk) 00:14, 4 December 2022 (UTC)

I support reversion. Xxanthippe (talk) 00:19, 4 December 2022 (UTC).

It seems to me that undergraduate mechanics texts (e.g., David Morin's Introduction to Classical Mechanics), as well as sources aimed at a broader audience, define mechanical energy or total energy as the sum of kinetic and potential energy and do not mention internal energy. Although I have not exhaustively cross-referenced or studied Feynman's lectures in detail, it appears that these changes reflect a minority viewpoint – WP:UNDUE weight – and thus I also support reversion. Nonetheless, a cited endnote mentioning this alternate definition could be appropriate; using endnotes to clarify nuances, exceptions, or less widespread viewpoints is fairly common practice. ^Complex/_Rational 02:42, 4 December 2022 (UTC)

This is not an undue issue because, as XOR mentioned, it's fairly obvious once you make the underlying assumptions known. It's just not an assumption that people generally make. I think @ComplexRational's solution is a good one. In any case, it's been more than a week, so any dispute should have petered out. Fermiboson (talk) 10:33, 4 December 2022 (UTC)

AfD

AfD at Wikipedia:Articles for deletion/Uniaxial crystal Fermiboson (talk) 05:47, 23 November 2022 (UTC)

Unrelatedly, Wikipedia:Articles for deletion/Mass–energy–information equivalence may also be of interest to the community here. XOR'easter (talk) 18:07, 23 November 2022 (UTC)

I see this theme come up repeatedly: quality of sources is very difficult to evaluate for most editors, and they tend to be swayed by volumes of hits. It seems to me that a tool that could flag each Google Scholar hits with the quality of publication would be a great benefit to editors. This is a bit of a dream, I suppose ... —Quondum 01:31, 24 November 2022 (UTC)

That's always been a problem with academia, and it kind of is impossible for laypeople to tell the difference (and I'm guilty of that too, having not actually read the paper in question before voting!) I suppose it has to be our (manual) job. Fermiboson (talk) 03:56, 24 November 2022 (UTC)

I will say that @XOR'easter's comment that "Conference proceedings don't count for jack" is only true in some fields. In accelerator physics, they are refereed, and actually the dominant form of publication, since there's so little journal space. That's an N of 1, but there may be other subfields where that is also true. PianoDan (talk) 17:15, 24 November 2022 (UTC)

Hmm, I was probably in a snappish mood when I made that remark; what I said in a later reply (and in my general advice page, now that I check) was a bit more measured. I can think of a few specific volumes devoted to particular conferences that are good reading, but none of those exceptions are relevant to this case. XOR'easter (talk) 22:20, 28 November 2022 (UTC)

Myriads of forever-to-be-stubs

What do others feel about the tendency to create a separate article for each variant of something instead of a redirect? It is not as though there is much to say about tera-, ronto-, quecto-, etc. (twenty-four of these in total!) that cannot be said at Metric prefix. These stubs also introduce a lot of duplication. Further, any examples that these might provide belong in the order-of-magnitude articles. —Quondum 20:20, 24 November 2022 (UTC)

I would prefer to see like stubs upmerged into a parent article from which they could be broken out again if content develops to justify that. BD2412 T 20:46, 24 November 2022 (UTC)

@Sheila1988: You might like to opine, given that you have recently added a few. —Quondum 21:17, 24 November 2022 (UTC)

Yes I suppose they could all be folded into a single article. The only really relevant info is the etymologies. Sheila1988 (talk) 21:05, 25 November 2022 (UTC)

Agreed, merge and redirect. Primefac (talk) 12:41, 26 November 2022 (UTC)

I'm not convinced that the etymologies are either valuable or accurate. At times, there may have been some mention of the thinking behind them, but I don't believe there is anything comprehensive or authoritative on this. Mostly it will be inference from the form. I have redirected the prefixes that look mostly the same (little content). Going through the more substantive ones (micro- to giga-) to see what should be merged will take a little more time. —Quondum 18:21, 26 November 2022 (UTC)

Draft article

I have created Draft:Method of virtual quanta, and would appreciate anyone more knowledgable in the topic to make the article more accurate/concise and sound less like Jackson. Fermiboson (talk) 11:23, 25 November 2022 (UTC)

Hypernucleus and subatomic particle notation

I've put this off for a few months now, but I am getting the final touches done on the article Hypernucleus. One sticking point is that I am as yet undecided on the use of names vs. symbols for meson and baryon names. For example, when referring to the lambda baryon in text, should I use:

• Λ exclusively in text, after identifying the Greek letter;
• "lambda" (lowercase) exclusively; or
• "Lambda" (capitalized) exclusively?

The symbols will still need to be introduced to shorthand more complex symbols, such as Σ⁺ vs. "sigma plus". –LaundryPizza03 (dc̄) 22:21, 26 November 2022 (UTC)

Scientific articles usually use the Greek letters, even in isolation (random example, see e.g. "according to the Λ decay position", no "lambda" anywhere in the paper), I think we should follow that approach and just add an introduction to the letters. --mfb (talk) 09:37, 29 November 2022 (UTC)

Nomination of Density (energy or power) for deletion

A discussion is taking place as to whether the article Density (energy or power) 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/Density (energy or power) 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.

–LaundryPizza03 (dc̄) 04:56, 28 November 2022 (UTC)

This is a disambiguation page concerning three related physical quantities. –LaundryPizza03 (dc̄) 04:56, 28 November 2022 (UTC)

Do we need Galilean non-invariance of electromagnetism?

The page Galilean non-invariance of classical electromagnetism is a bit odd. (1) why restrain it to classical electromagnetism (2) weird lead and writing in general (also headers that should be sub headers and so on) (3) it seems it could be merged into electromagnetism or Galilean invariance or something like that. As it is, the article seems too specific unless it is there for historical issues but then the history part is missing. Any thoughts are welcome. See also the talk. ReyHahn (talk) 09:38, 28 November 2022 (UTC)

Yeah I would AfD it. The article seems to be based on this obscure reference [6]. The opening sentence is already outrageously wrong: If Galilean transformations were invariant for not only mechanics but also electromagnetism, Newtonian relativity would hold for the whole of the physics. The subject is quite weird, deserving no more of a footnote in treatments of classical electromagnetism. The entire contents of the article are a violation of WP:NOTTEXTBOOK. To top off, its last reference [7] is hair-raising crackpottery. Tercer (talk) 10:26, 28 November 2022 (UTC)

As well as I know the story, it was this non-invariance that was important in developing special relativity. As noted, though, one does have to be careful with WP:NOTTEXTBOOK. Including the appropriate history, which might not be done well otherwise, could be enough to fix it. Some of the history is in Lorentz transformation, but maybe not all of it. The again, Lorentz transformation might be the place to fix it. We could even redirect this to a section in that page. Gah4 (talk) 16:25, 28 November 2022 (UTC)

I agree with taking it to AfD, basically because it has nothing usefully salvageable. There is a core idea that is valid and well-understood [although not by me], essentially that there is a broad class of diffeomorphisms that respect Maxwell's equations in terms of the EM 2-form and charge–current 3-form. The Galilean transformations are not special [whether they are included or not; I suspect not, as per Gah4]. This could be started as a section in Classical electromagnetism, but not through a merge. The concept is a bit counterintuitive, and I'm no expert. but even John Baez has made reference to this. —Quondum 17:17, 28 November 2022 (UTC)

Thanks you for your feedback. A deleting discussion has been created Wikipedia:Articles for deletion/Galilean non-invariance of classical electromagnetism.--ReyHahn (talk) 13:44, 1 December 2022 (UTC)