This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
A new user, Gdrg22 ( talk · contribs), seems to be trying to contribute to relativity-related articles. Unfortunately right now that includes copy/pasting (or substing) the relativity sidebar into a couple of articles ( Hawking radiation and Wormhole that I notice offhand). I've reverted these and left a polite note on their talk page explaining how curly-braces work.
They've also made nontrivial changes to many other articles, which I don't have time to vet at the moment but which could probably use scrutiny. At a glance, they've tweaked several relativity related articles, made adjustments to Template:General relativity to add names, removed material from nuclear fission (haven't checked what), and contributed quite a lot of talk page material to an AFC for an aether-based theory of gravity. -- Christopher Thomas ( talk) 22:05, 31 July 2012 (UTC)
By the way, in Template:General relativity... Millikan and De Pretto as major contributors to general relativity? And Lorentz? - DVdm ( talk) 14:32, 3 August 2012 (UTC)
I think someone more knowledgeable in history of physics than me should have a close look at the recent activities of Gdrg22 ( talk · contribs):
Most of this is probably in good faith, but it could use some expert attention. — HHHIPPO 21:45, 4 August 2012 (UTC)
brian shicmidt with Nicholas_B._Suntzeff (which is jewish) founded 'High-z Supernova Search Team' adam riess and the other get the credits from other jewish
chamberlain the leader maide the most contribuitions , i read this in a book 'segre'is the assistant - and i didnt know that he was jewish im not even entered his wiki page - and there are some controverses envolving him.
i exclude annon alan pezias name because it was already included in the introdution it was more for estetic and visual i felt strange i never seen a name which are not from the main person of the wiki page foccused. i wanted to deleted and just but later i gave up — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 17:08, 5 August 2012 (UTC)
about the V- A theory i know that two of the creators of eletroweak theory are jewish but one is muslim and the main boss "Abdus Salam" its unfair because it was an indian american who did it
and to make me clear im from brazil , i never met a jewish before , there are few jews in brazil and most of them live of the south im from north, it was only concidence, and i didnt know they were jews when i added lev landau and perl to templates
and for end the real discover of nucler fission was otto hahn not lise - which i didnt know was jewish
it might not be intentional but after this edebate when i knew that all scientists who were get overrated attention from others works were jewish it seems - an hipotetical- that a jewish included "lower level" scientists and excluded great scientists from the history , and one more thing there are lot of jews in quantum mechanics template and i didnt remove them because the nobel criteria , for me , in a especific field is not valid all contribuited
thx for attention — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 17:15, 5 August 2012 (UTC)
im ending my participation in wikipedia after all this "controversy", i dont want any kind of negative attention for me especially racism subject
thanks anyway — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 20:17, 5 August 2012 (UTC)
Dear Gdrg22. Well it's up to you, but thank you for your contributions some of which I thought were good changes.
To everyone else, perhaps we could review the following changes (some may already have been reverted, I haven't checked them all). These edits cause me some concern as they appear to be an attempt to de-emphasise certain physicists:
Thanks. CodeTheorist ( talk) 21:29, 5 August 2012 (UTC)
The usage of Supermassive Black Hole is under discussion, see Talk:Supermassive Black Hole (song) -- 76.65.131.160 ( talk) 02:53, 1 August 2012 (UTC)
I have a dispute with one ultramergist user of the type "let us expand the article to discuss a variety of applications of the word". This is not a complex case, it needs just a couple of experienced users to enforce certain well-known Wikipedia guidelines, see details. Incnis Mrsi ( talk) 11:51, 5 August 2012 (UTC)
Yet another "article about the term" but, unlike the topic just above, the case is quite interesting. Several users at talk: Steam tried to formulate a valid definition, to no avail.
To my opinion, "Steam" should not be an article, but probably a dab page, or maybe a redirect to vapor with a dab hatnote. Contrary to the current order on Steam (disambiguation), it should start with the most general sense, that steam means "vapor", a gaseous phase of matter, most usually water vapor. Then, steam engine is the most common application of the word (BTW it not necessarily uses a water vapor). Only after that should follow "steaming" and all items below. Incnis Mrsi ( talk) 06:00, 6 August 2012 (UTC)
Accidently, I discovered yet another article: live steam. Awaiting for a cleanup of all this stuff, preferably by users with native English. Incnis Mrsi ( talk) 08:56, 6 August 2012 (UTC)
I've had Isidor Isaac Rabi nominated for GA since 8 June, and no takers so far. I have to travel overseas in a couple of weeks, so if anyone would like to have a go at reviewing the article, it would be very much appreciated. Hawkeye7 ( talk) 21:45, 7 August 2012 (UTC)
There is a regular problem throughout the science and mathematics articles in Wikipedia. It should be possible for someone doing their high-school homework to look up a subject and get a comprehensible explanation. A typical example is the article on Momentum, which starts with a vector equation. Although the present policy in WP is purist and technically impeccable, many articles on basic physics and applied mathematics are virtually useless for all but the cognescenti. Of course the heavyweight material can follow, but it should not be in the introduction or in the first few paragraphs until a simple, even if incomplete, explanation has been provided. JMcC ( talk) 10:04, 22 July 2012 (UTC)
I think that all articles should have the first introductory paragraph be an explanation in simple terms geared towards an average English-as-a-second-language or high-school-dropout reader. The rest of the introduction can be more complex, for the intelligent adult reader with a fair grasp of English. Anything requiring more than that in the section-0/introduction should be avoided. A more technical introduction can be given in a summary section, immediately following the introduction, for those readers who are subject literate. If the subject/topic is dense, then a full Introduction to X article might need to be built. But again, these introduction features should be there regardless of whether or not an Introduction article exists. (it might just direct people to the introduction article after the first simple paragraph, though) -- 76.65.131.160 ( talk) 04:16, 23 July 2012 (UTC)
I have waited a while, but the discussion seems to have petered out. I think we have agreement that it is unrealistic for an article on an advanced aspect of physics to be written for people who do not know the basics. However there are a group of basic articles that could be a point of entry for the layman. Momentum is one of these. We have to decide if a basic introduction is a separate article or is a replacement for the current intro that mentions vectors and relativity. I had a go at writing something and I will let you all decide whether that points to a separate article or a rethink on how we write introductions.
Momentum (plural momenta) is a measure used in classical physics to describe mass in motion. It is sometimes known as linear momentum or translational momentum.
All objects have mass; so if an object is moving, then it has momentum. The momentum of an object depends on how much mass is moving and its velocity. It is calculated using:
Momentum = mass • velocity
Because velocity is a speed in a specified direction, an object's momentum also has a direction as well as magnitude. Quantities that have both a magnitude and a direction are known as vector quantities. That is why there is a dot in the equation above, rather than a simple multiplication sign. Because momentum has a direction, it can be used to predict the resulting direction of objects after they collide, as well as their speeds.
Physicist use 'p' as the symbol for momentum, so the equation above can be rewritten as: p = m • v where m is the mass and v is the velocity. When using the SI system, its units are kilograms metres per second. For example a car with a mass of 1,000kg travelling at a speed of 30m/s westward would have a momentum of 30,000 kg.m/s
Don't pitch in to say I have got my physics wrong. This quite likely. This rough draft probably has all sorts of issues, but just view this as the level at which I would aim the intro (or a separate article. JMcC ( talk) 11:47, 30 July 2012 (UTC).
Yes, there are topics which would be nearly impossible to explain to non-experts, and there are particularly stupid people to whom it'd be nearly impossible to explain any advanced topics. But this effect is waaaaay overestimated; often the reason why people say something can't be explained in an accessible way is that they never seriously try to do that in the first place. (People said it would be impossible to make the lead of this more accessible, but a month later it looked like this.) As a rule of thumb, I'd say that if you've heard about a topic as an undergrad, then almost surely it's possible in principle to explain it in a way that an intelligent layman would reasonably understand. Refraction? FFS... When light passes from a medium to another, it changes direction. (That's why a pencil partly in water looks broken, and the way lenses work.) And the amount by which it changes direction can depend on the colour of the light; since white light is a mixture of light of different colours, you get rainbows. Even my grandma would understand this. The quantum mechanical mechanism by which that happens is more complicated, but I can't see why more than a short mention of it is needed in the lead section; the place to discuss it in detail is the body of the article. As for gauge theories, Lie groups, and Riemannian manifolds, I think I could explain them in a way that intelligent laymen could understand (at least the general ideas, though not the technical details), but that'd take more than a couple paragraphs so if we wanted to do that we'd need “Introduction to ...” articles. Now, explaining what a Ward–Takahashi identity is to my sister would be pretty much impossible, but the lead of that article would ideally be written in a way that someone reading it would understand that it's a mathematical identity useful in theoretical particle physics, and that they would need to understand quantum field theory to understand it. A. di M. ( talk) 22:47, 31 July 2012 (UTC)
I think it is important to make physics articles accessible to as broad an audience as possible. Several ideas have come out of the recent CfD on Category:Introductory physics that might be worth pursuing. These include new articles ( Introduction to physics and List of introductory physics topics). There are also administrative aids like Wikipedia:WikiProject Mathematics/Wikipedia_1.0/Basics, membership in which is triggered by a field in the {{ maths rating}} template. Maybe even a working group on introductory physics could be justified. RockMagnetist ( talk) 15:54, 22 July 2012 (UTC)
I have created List of physics concepts in pre-college curricula, and one lesson I learned from doing it is that it is much easier to do a good job of a list than a category. I basically translated the California high school physics standards into a list. RockMagnetist ( talk) 22:15, 24 July 2012 (UTC)
I smiled when I read what User:Christopher Thomas says above: If you attempt this for just about any high-level math topic, you'll wind up with "it's a type of thing" or "it's a thing that relates type A things and type B things". Literally, that's what you'll end up with. Christopher is perhaps unwittingly using the language of category theory, talking about objects and arrows. Perhaps we should be teaching category theory to grade-school children. The children would understand, but sadly, the parents would have the teacher's head on a pike by the end of the month, and so here we are... linas ( talk) 03:29, 18 August 2012 (UTC)
I am wondering if people are aware that Nuclear Physics Laboratory is a redirect to Denys Wilkinson Building. Although it seems to serve as a proper name, I think this is useful as a general description or a disambiguation page (if it is needed). ---- Steve Quinn ( talk) 19:02, 7 August 2012 (UTC)
What to do about the stubby Position space (r-space)? Add material or merge?
One possibility is the rewritten (by me) position (vector) article, which links to and describes position space.
A better place (I'd be inclined) is to merge into momentum space (k-space) since this already contains info on k and r as the spatial analogue to angular frequency ω and time t, and that functions of r can be Fourier transformed into functions of k and vice versa because of the space-inverse space relation. It can and should be extended to 3d though... If so, what would the best title be for the merged article: "position-momentum space", or "position and momentum spaces" (obviously with the separate articles as redirects)?
By all means closely related articles like reciprocal lattice, phase space, configuration space should be left alone, but position space needs to go somewhere...
What do others think? Thanks in advance for any/all help. Maschen ( talk) 07:07, 16 August 2012 (UTC)
It would have been nicer to move the old article to the new name, instead of doing a cut n paste n delete of content; a move would have preserved both the edit history and the talk page... Next time, please move, instead of cut-n-pasting.
Also: should mention e.g. that its all a special case of pontryagin duality, as this opens the door to many othter concepts in physics. linas ( talk) 01:53, 18 August 2012 (UTC)
In the recent spirits of improving momentum-related articles, an editor has tagged this article as "too technical", another says it makes no sense mathematically (see talk:momentum operator#Definition). I'm not sure how much more accessible to make it. Opinions? If others can then feel free. Maschen ( talk) 23:30, 17 August 2012 (UTC)
Yeah, I think the issue raised on the talk page is that neither the domain nor the codomain are specified. Are these bounded functions? square-integrable functions? using what measure? does it require uniform convergence? or any convergence at all? The momentum operator is not a bounded operator, its not trace class, which means it has discontinuities, as typical in Frechet space, and etc. So, yeah, the article really does "make no sense" at all, although the sloppy presentation given is not atypical of an undergrad physics textbook treatment, which sweeps all such details under the rug. We do a dis-service by ignoring such details. linas ( talk) 02:01, 18 August 2012 (UTC)
The other thing I find incredibly annoying about such articles is the utter lack of historical context. This is an operator that Bohr and Sommerfeld vaguely though about in 1910 or 1920 or whenever, and Schrodinger, and Wigner, and many others fully elucidated a while later. I wish the history were there... linas ( talk) 02:08, 18 August 2012 (UTC)
Would it not be desirable to mention that the wave function can be approximated by
where A is a normalization constant and S is
Hamilton's principal function. I just realized that this formula, which I had long assumed was correct, is wrong because it has the wrong variables. While S is a function of both the qs and the ps (and t), ψ is a function of either the qs or the ps but not both. Any ideas on how to fix it? I see that I should read the articles to which I am linking before linking them.
JRSpriggs (
talk)
04:45, 18 August 2012 (UTC)
I've probably wasted too many electrons here already, but here's another example: the time evolution of an undisturbed quantum mechanical system is given by a unitary operator (by exp(iHt) to be precise, H the Hamiltonian). The eigenvalues of a unitary operator all lie on the unit circle. However, bump the system, force decoherence, or a quantum measurement, you stop the unitary evolution, you get a dissipative system. The eigenvalues are knocked inside the unit circle; time is no longer reversible (backwards time would mean eigenvalues lie outside the circle; running time backwards would explode the system). One way to understand this is that when you force decoherence, you are no longer using the usual square-integrable wave functions of QM, you are using a different space that models (for example) a thermal bath (or whatever). The details depend on the journal, the author and the decade in which the article was written. linas ( talk) 05:46, 18 August 2012 (UTC)
I hardly think this is actually a worthwhile "article". It has zero sources, and is just one of the "suvat" equations with an elaborate derivation.
Maybe this can be merged into the section Equations of motion, Constant linear acceleration: mentioning one of the suvat equations was also found (and not "created") by Torricelli?
This has already been suggested here way back in 2005, to no effect... Maschen ( talk) 14:53, 16 August 2012 (UTC)
Please see here. The magnetic monopoles#appendix section has been copied from this site. Ideally it should be rewritten, although I don't understand Yang-Mills theory so can't do much about that... sorry. Maschen ( talk) 12:17, 18 August 2012 (UTC)
This is a pointless "article": three sentences about the torque exerted on water molecule dipoles in food due to microwave radiation in a microwave oven. It doesn't even get the terminology right: "electric torque is the force heating water in the microwave oven". It should be just blanked, redirected, perhaps mentioned in the electric dipole moment article. Maschen ( talk) 11:36, 21 August 2012 (UTC)
The photon article states that the isospin of a photon can be either 0 or 1. I thought this was clearly nonsense, but the PDG does list the photon has having either isospin 0 or 1, which is making me question a whole lot of things about what I know about isospin. This post on physics.stackexchange.com seems to say that the PDG is somehow referring to weak isospin, but why in the world would they recycle the I symbol for that when everywhere else it means normal isospin? Can anyone make any sense of this? Headbomb { talk / contribs / physics / books} 15:33, 18 August 2012 (UTC)
Ok so to recap, and make sure I understand things, the strong interaction-related isospin due to the up/down quarks (which I'll call Iud) of photons is indeed zero, but some other SU(2) symmetry, the weak interaction-related isospin (which I'll call IW), can be either 0 or 1 (or a mix of 0 and 1?). That is when the PDG writes I(JP) of say mesons [4], they really mean Iud(JP), but when they write the I(JP) of photons [5] and possibly gluons [6], they really mean IW(JP)? Because if so, the PDG should really come up with better symbol use, or make it abundantly clear what I is exactly referring to. Headbomb { talk / contribs / physics / books} 21:53, 18 August 2012 (UTC)
You really really really should read up on the representations of the rotation group SO(3). Sadly, WP is not the place to do it, we don't even have a stand-alone article on SU(2). But once you study angular momentum in depth, I think a lot of this will make a lot more sense. (Its the prototype for all the other SU's and opens the doors to many things) linas ( talk) 05:53, 21 August 2012 (UTC)
I recently wrote a section about isospin symmetry: Particle physics and representation theory#Example: isospin symmetry. (I was using it as a simple example of how approximate symmetries give rise to groupings of particles.) I was assuming that isospin related only to up and down quarks, but it sounds like the truth is more complicated. Or maybe that I should clarify the way in which "isospin" is used. I hope someone can take a look and correct any inaccuracies... -- Steve ( talk) 12:42, 22 August 2012 (UTC)
Stanislaw Ulam has been proposed to be renamed, see Talk:Stanislaw Ulam -- 76.65.128.252 ( talk) 04:40, 23 August 2012 (UTC)
BTW, I noticed recently that you could access article feedback from your watchlist. It's a good way to make a link between the readers of an article, and editors, in that readers will often make suggestions for the article. Unfortunately, most of the feedback is useless, but there are a couple of gems here and there. It would be good for the physics project if people checked their watchlist's feedback every couple of days, and resolve issues as they arise. I'm sure it would greatly improve the quality of a couple of our pages. Headbomb { talk / contribs / physics / books} 17:21, 24 August 2012 (UTC)
The article Stephen Hawking (one of our top importance articles) has been nominated as a WP:Feature article. If you have time, please have a look and leave comments at Wikipedia:Featured_article_candidates/Stephen_Hawking/archive3. T R 12:55, 26 August 2012 (UTC)
Please, could anyone take a look at Special:Contributions/Al126_at_wiki and maybe help the new editor? Some of their contributions have been deleted, and I'm not sure with the rest. Thanks for any assistance. -- Vejvančický ( talk | contribs) 12:11, 30 August 2012 (UTC)
This page is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
A new user, Gdrg22 ( talk · contribs), seems to be trying to contribute to relativity-related articles. Unfortunately right now that includes copy/pasting (or substing) the relativity sidebar into a couple of articles ( Hawking radiation and Wormhole that I notice offhand). I've reverted these and left a polite note on their talk page explaining how curly-braces work.
They've also made nontrivial changes to many other articles, which I don't have time to vet at the moment but which could probably use scrutiny. At a glance, they've tweaked several relativity related articles, made adjustments to Template:General relativity to add names, removed material from nuclear fission (haven't checked what), and contributed quite a lot of talk page material to an AFC for an aether-based theory of gravity. -- Christopher Thomas ( talk) 22:05, 31 July 2012 (UTC)
By the way, in Template:General relativity... Millikan and De Pretto as major contributors to general relativity? And Lorentz? - DVdm ( talk) 14:32, 3 August 2012 (UTC)
I think someone more knowledgeable in history of physics than me should have a close look at the recent activities of Gdrg22 ( talk · contribs):
Most of this is probably in good faith, but it could use some expert attention. — HHHIPPO 21:45, 4 August 2012 (UTC)
brian shicmidt with Nicholas_B._Suntzeff (which is jewish) founded 'High-z Supernova Search Team' adam riess and the other get the credits from other jewish
chamberlain the leader maide the most contribuitions , i read this in a book 'segre'is the assistant - and i didnt know that he was jewish im not even entered his wiki page - and there are some controverses envolving him.
i exclude annon alan pezias name because it was already included in the introdution it was more for estetic and visual i felt strange i never seen a name which are not from the main person of the wiki page foccused. i wanted to deleted and just but later i gave up — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 17:08, 5 August 2012 (UTC)
about the V- A theory i know that two of the creators of eletroweak theory are jewish but one is muslim and the main boss "Abdus Salam" its unfair because it was an indian american who did it
and to make me clear im from brazil , i never met a jewish before , there are few jews in brazil and most of them live of the south im from north, it was only concidence, and i didnt know they were jews when i added lev landau and perl to templates
and for end the real discover of nucler fission was otto hahn not lise - which i didnt know was jewish
it might not be intentional but after this edebate when i knew that all scientists who were get overrated attention from others works were jewish it seems - an hipotetical- that a jewish included "lower level" scientists and excluded great scientists from the history , and one more thing there are lot of jews in quantum mechanics template and i didnt remove them because the nobel criteria , for me , in a especific field is not valid all contribuited
thx for attention — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 17:15, 5 August 2012 (UTC)
im ending my participation in wikipedia after all this "controversy", i dont want any kind of negative attention for me especially racism subject
thanks anyway — Preceding unsigned comment added by Gdrg22 ( talk • contribs) 20:17, 5 August 2012 (UTC)
Dear Gdrg22. Well it's up to you, but thank you for your contributions some of which I thought were good changes.
To everyone else, perhaps we could review the following changes (some may already have been reverted, I haven't checked them all). These edits cause me some concern as they appear to be an attempt to de-emphasise certain physicists:
Thanks. CodeTheorist ( talk) 21:29, 5 August 2012 (UTC)
The usage of Supermassive Black Hole is under discussion, see Talk:Supermassive Black Hole (song) -- 76.65.131.160 ( talk) 02:53, 1 August 2012 (UTC)
I have a dispute with one ultramergist user of the type "let us expand the article to discuss a variety of applications of the word". This is not a complex case, it needs just a couple of experienced users to enforce certain well-known Wikipedia guidelines, see details. Incnis Mrsi ( talk) 11:51, 5 August 2012 (UTC)
Yet another "article about the term" but, unlike the topic just above, the case is quite interesting. Several users at talk: Steam tried to formulate a valid definition, to no avail.
To my opinion, "Steam" should not be an article, but probably a dab page, or maybe a redirect to vapor with a dab hatnote. Contrary to the current order on Steam (disambiguation), it should start with the most general sense, that steam means "vapor", a gaseous phase of matter, most usually water vapor. Then, steam engine is the most common application of the word (BTW it not necessarily uses a water vapor). Only after that should follow "steaming" and all items below. Incnis Mrsi ( talk) 06:00, 6 August 2012 (UTC)
Accidently, I discovered yet another article: live steam. Awaiting for a cleanup of all this stuff, preferably by users with native English. Incnis Mrsi ( talk) 08:56, 6 August 2012 (UTC)
I've had Isidor Isaac Rabi nominated for GA since 8 June, and no takers so far. I have to travel overseas in a couple of weeks, so if anyone would like to have a go at reviewing the article, it would be very much appreciated. Hawkeye7 ( talk) 21:45, 7 August 2012 (UTC)
There is a regular problem throughout the science and mathematics articles in Wikipedia. It should be possible for someone doing their high-school homework to look up a subject and get a comprehensible explanation. A typical example is the article on Momentum, which starts with a vector equation. Although the present policy in WP is purist and technically impeccable, many articles on basic physics and applied mathematics are virtually useless for all but the cognescenti. Of course the heavyweight material can follow, but it should not be in the introduction or in the first few paragraphs until a simple, even if incomplete, explanation has been provided. JMcC ( talk) 10:04, 22 July 2012 (UTC)
I think that all articles should have the first introductory paragraph be an explanation in simple terms geared towards an average English-as-a-second-language or high-school-dropout reader. The rest of the introduction can be more complex, for the intelligent adult reader with a fair grasp of English. Anything requiring more than that in the section-0/introduction should be avoided. A more technical introduction can be given in a summary section, immediately following the introduction, for those readers who are subject literate. If the subject/topic is dense, then a full Introduction to X article might need to be built. But again, these introduction features should be there regardless of whether or not an Introduction article exists. (it might just direct people to the introduction article after the first simple paragraph, though) -- 76.65.131.160 ( talk) 04:16, 23 July 2012 (UTC)
I have waited a while, but the discussion seems to have petered out. I think we have agreement that it is unrealistic for an article on an advanced aspect of physics to be written for people who do not know the basics. However there are a group of basic articles that could be a point of entry for the layman. Momentum is one of these. We have to decide if a basic introduction is a separate article or is a replacement for the current intro that mentions vectors and relativity. I had a go at writing something and I will let you all decide whether that points to a separate article or a rethink on how we write introductions.
Momentum (plural momenta) is a measure used in classical physics to describe mass in motion. It is sometimes known as linear momentum or translational momentum.
All objects have mass; so if an object is moving, then it has momentum. The momentum of an object depends on how much mass is moving and its velocity. It is calculated using:
Momentum = mass • velocity
Because velocity is a speed in a specified direction, an object's momentum also has a direction as well as magnitude. Quantities that have both a magnitude and a direction are known as vector quantities. That is why there is a dot in the equation above, rather than a simple multiplication sign. Because momentum has a direction, it can be used to predict the resulting direction of objects after they collide, as well as their speeds.
Physicist use 'p' as the symbol for momentum, so the equation above can be rewritten as: p = m • v where m is the mass and v is the velocity. When using the SI system, its units are kilograms metres per second. For example a car with a mass of 1,000kg travelling at a speed of 30m/s westward would have a momentum of 30,000 kg.m/s
Don't pitch in to say I have got my physics wrong. This quite likely. This rough draft probably has all sorts of issues, but just view this as the level at which I would aim the intro (or a separate article. JMcC ( talk) 11:47, 30 July 2012 (UTC).
Yes, there are topics which would be nearly impossible to explain to non-experts, and there are particularly stupid people to whom it'd be nearly impossible to explain any advanced topics. But this effect is waaaaay overestimated; often the reason why people say something can't be explained in an accessible way is that they never seriously try to do that in the first place. (People said it would be impossible to make the lead of this more accessible, but a month later it looked like this.) As a rule of thumb, I'd say that if you've heard about a topic as an undergrad, then almost surely it's possible in principle to explain it in a way that an intelligent layman would reasonably understand. Refraction? FFS... When light passes from a medium to another, it changes direction. (That's why a pencil partly in water looks broken, and the way lenses work.) And the amount by which it changes direction can depend on the colour of the light; since white light is a mixture of light of different colours, you get rainbows. Even my grandma would understand this. The quantum mechanical mechanism by which that happens is more complicated, but I can't see why more than a short mention of it is needed in the lead section; the place to discuss it in detail is the body of the article. As for gauge theories, Lie groups, and Riemannian manifolds, I think I could explain them in a way that intelligent laymen could understand (at least the general ideas, though not the technical details), but that'd take more than a couple paragraphs so if we wanted to do that we'd need “Introduction to ...” articles. Now, explaining what a Ward–Takahashi identity is to my sister would be pretty much impossible, but the lead of that article would ideally be written in a way that someone reading it would understand that it's a mathematical identity useful in theoretical particle physics, and that they would need to understand quantum field theory to understand it. A. di M. ( talk) 22:47, 31 July 2012 (UTC)
I think it is important to make physics articles accessible to as broad an audience as possible. Several ideas have come out of the recent CfD on Category:Introductory physics that might be worth pursuing. These include new articles ( Introduction to physics and List of introductory physics topics). There are also administrative aids like Wikipedia:WikiProject Mathematics/Wikipedia_1.0/Basics, membership in which is triggered by a field in the {{ maths rating}} template. Maybe even a working group on introductory physics could be justified. RockMagnetist ( talk) 15:54, 22 July 2012 (UTC)
I have created List of physics concepts in pre-college curricula, and one lesson I learned from doing it is that it is much easier to do a good job of a list than a category. I basically translated the California high school physics standards into a list. RockMagnetist ( talk) 22:15, 24 July 2012 (UTC)
I smiled when I read what User:Christopher Thomas says above: If you attempt this for just about any high-level math topic, you'll wind up with "it's a type of thing" or "it's a thing that relates type A things and type B things". Literally, that's what you'll end up with. Christopher is perhaps unwittingly using the language of category theory, talking about objects and arrows. Perhaps we should be teaching category theory to grade-school children. The children would understand, but sadly, the parents would have the teacher's head on a pike by the end of the month, and so here we are... linas ( talk) 03:29, 18 August 2012 (UTC)
I am wondering if people are aware that Nuclear Physics Laboratory is a redirect to Denys Wilkinson Building. Although it seems to serve as a proper name, I think this is useful as a general description or a disambiguation page (if it is needed). ---- Steve Quinn ( talk) 19:02, 7 August 2012 (UTC)
What to do about the stubby Position space (r-space)? Add material or merge?
One possibility is the rewritten (by me) position (vector) article, which links to and describes position space.
A better place (I'd be inclined) is to merge into momentum space (k-space) since this already contains info on k and r as the spatial analogue to angular frequency ω and time t, and that functions of r can be Fourier transformed into functions of k and vice versa because of the space-inverse space relation. It can and should be extended to 3d though... If so, what would the best title be for the merged article: "position-momentum space", or "position and momentum spaces" (obviously with the separate articles as redirects)?
By all means closely related articles like reciprocal lattice, phase space, configuration space should be left alone, but position space needs to go somewhere...
What do others think? Thanks in advance for any/all help. Maschen ( talk) 07:07, 16 August 2012 (UTC)
It would have been nicer to move the old article to the new name, instead of doing a cut n paste n delete of content; a move would have preserved both the edit history and the talk page... Next time, please move, instead of cut-n-pasting.
Also: should mention e.g. that its all a special case of pontryagin duality, as this opens the door to many othter concepts in physics. linas ( talk) 01:53, 18 August 2012 (UTC)
In the recent spirits of improving momentum-related articles, an editor has tagged this article as "too technical", another says it makes no sense mathematically (see talk:momentum operator#Definition). I'm not sure how much more accessible to make it. Opinions? If others can then feel free. Maschen ( talk) 23:30, 17 August 2012 (UTC)
Yeah, I think the issue raised on the talk page is that neither the domain nor the codomain are specified. Are these bounded functions? square-integrable functions? using what measure? does it require uniform convergence? or any convergence at all? The momentum operator is not a bounded operator, its not trace class, which means it has discontinuities, as typical in Frechet space, and etc. So, yeah, the article really does "make no sense" at all, although the sloppy presentation given is not atypical of an undergrad physics textbook treatment, which sweeps all such details under the rug. We do a dis-service by ignoring such details. linas ( talk) 02:01, 18 August 2012 (UTC)
The other thing I find incredibly annoying about such articles is the utter lack of historical context. This is an operator that Bohr and Sommerfeld vaguely though about in 1910 or 1920 or whenever, and Schrodinger, and Wigner, and many others fully elucidated a while later. I wish the history were there... linas ( talk) 02:08, 18 August 2012 (UTC)
Would it not be desirable to mention that the wave function can be approximated by
where A is a normalization constant and S is
Hamilton's principal function. I just realized that this formula, which I had long assumed was correct, is wrong because it has the wrong variables. While S is a function of both the qs and the ps (and t), ψ is a function of either the qs or the ps but not both. Any ideas on how to fix it? I see that I should read the articles to which I am linking before linking them.
JRSpriggs (
talk)
04:45, 18 August 2012 (UTC)
I've probably wasted too many electrons here already, but here's another example: the time evolution of an undisturbed quantum mechanical system is given by a unitary operator (by exp(iHt) to be precise, H the Hamiltonian). The eigenvalues of a unitary operator all lie on the unit circle. However, bump the system, force decoherence, or a quantum measurement, you stop the unitary evolution, you get a dissipative system. The eigenvalues are knocked inside the unit circle; time is no longer reversible (backwards time would mean eigenvalues lie outside the circle; running time backwards would explode the system). One way to understand this is that when you force decoherence, you are no longer using the usual square-integrable wave functions of QM, you are using a different space that models (for example) a thermal bath (or whatever). The details depend on the journal, the author and the decade in which the article was written. linas ( talk) 05:46, 18 August 2012 (UTC)
I hardly think this is actually a worthwhile "article". It has zero sources, and is just one of the "suvat" equations with an elaborate derivation.
Maybe this can be merged into the section Equations of motion, Constant linear acceleration: mentioning one of the suvat equations was also found (and not "created") by Torricelli?
This has already been suggested here way back in 2005, to no effect... Maschen ( talk) 14:53, 16 August 2012 (UTC)
Please see here. The magnetic monopoles#appendix section has been copied from this site. Ideally it should be rewritten, although I don't understand Yang-Mills theory so can't do much about that... sorry. Maschen ( talk) 12:17, 18 August 2012 (UTC)
This is a pointless "article": three sentences about the torque exerted on water molecule dipoles in food due to microwave radiation in a microwave oven. It doesn't even get the terminology right: "electric torque is the force heating water in the microwave oven". It should be just blanked, redirected, perhaps mentioned in the electric dipole moment article. Maschen ( talk) 11:36, 21 August 2012 (UTC)
The photon article states that the isospin of a photon can be either 0 or 1. I thought this was clearly nonsense, but the PDG does list the photon has having either isospin 0 or 1, which is making me question a whole lot of things about what I know about isospin. This post on physics.stackexchange.com seems to say that the PDG is somehow referring to weak isospin, but why in the world would they recycle the I symbol for that when everywhere else it means normal isospin? Can anyone make any sense of this? Headbomb { talk / contribs / physics / books} 15:33, 18 August 2012 (UTC)
Ok so to recap, and make sure I understand things, the strong interaction-related isospin due to the up/down quarks (which I'll call Iud) of photons is indeed zero, but some other SU(2) symmetry, the weak interaction-related isospin (which I'll call IW), can be either 0 or 1 (or a mix of 0 and 1?). That is when the PDG writes I(JP) of say mesons [4], they really mean Iud(JP), but when they write the I(JP) of photons [5] and possibly gluons [6], they really mean IW(JP)? Because if so, the PDG should really come up with better symbol use, or make it abundantly clear what I is exactly referring to. Headbomb { talk / contribs / physics / books} 21:53, 18 August 2012 (UTC)
You really really really should read up on the representations of the rotation group SO(3). Sadly, WP is not the place to do it, we don't even have a stand-alone article on SU(2). But once you study angular momentum in depth, I think a lot of this will make a lot more sense. (Its the prototype for all the other SU's and opens the doors to many things) linas ( talk) 05:53, 21 August 2012 (UTC)
I recently wrote a section about isospin symmetry: Particle physics and representation theory#Example: isospin symmetry. (I was using it as a simple example of how approximate symmetries give rise to groupings of particles.) I was assuming that isospin related only to up and down quarks, but it sounds like the truth is more complicated. Or maybe that I should clarify the way in which "isospin" is used. I hope someone can take a look and correct any inaccuracies... -- Steve ( talk) 12:42, 22 August 2012 (UTC)
Stanislaw Ulam has been proposed to be renamed, see Talk:Stanislaw Ulam -- 76.65.128.252 ( talk) 04:40, 23 August 2012 (UTC)
BTW, I noticed recently that you could access article feedback from your watchlist. It's a good way to make a link between the readers of an article, and editors, in that readers will often make suggestions for the article. Unfortunately, most of the feedback is useless, but there are a couple of gems here and there. It would be good for the physics project if people checked their watchlist's feedback every couple of days, and resolve issues as they arise. I'm sure it would greatly improve the quality of a couple of our pages. Headbomb { talk / contribs / physics / books} 17:21, 24 August 2012 (UTC)
The article Stephen Hawking (one of our top importance articles) has been nominated as a WP:Feature article. If you have time, please have a look and leave comments at Wikipedia:Featured_article_candidates/Stephen_Hawking/archive3. T R 12:55, 26 August 2012 (UTC)
Please, could anyone take a look at Special:Contributions/Al126_at_wiki and maybe help the new editor? Some of their contributions have been deleted, and I'm not sure with the rest. Thanks for any assistance. -- Vejvančický ( talk | contribs) 12:11, 30 August 2012 (UTC)