Wikipedia talk:WikiProject Physics/Archive October 2014

Comment on the WikiProject X proposal

Hello there! As you may already know, most WikiProjects here on Wikipedia struggle to stay active after they've been founded. I believe there is a lot of potential for WikiProjects to facilitate collaboration across subject areas, so I have submitted a grant proposal with the Wikimedia Foundation for the "WikiProject X" project. WikiProject X will study what makes WikiProjects succeed in retaining editors and then design a prototype WikiProject system that will recruit contributors to WikiProjects and help them run effectively. Please review the proposal here and leave feedback. If you have any questions, you can ask on the proposal page or leave a message on my talk page. Thank you for your time! (Also, sorry about the posting mistake earlier. If someone already moved my message to the talk page, feel free to remove this posting.) Harej (talk) 22:47, 1 October 2014 (UTC)

Skein and hyperspace

In some sci-fi the word Skein gets used to describe regular space-time, generally in opposition to hyperspace —Iain Banks and Star Wars, but not Asimov, I think. I was curious to the meaning/link, but I could not find anything on Skein —I posted there, but I thought it best to double post. I am not a physicist, so I thought it best to ask you chaps. --Squidonius (talk) 01:19, 6 October 2014 (UTC)

Highly likely that the author(s) that coined that term did so as to make it slightly different from "skin" (which is my interpretation of every instance I've found in my search for the word). I'm not sure it's worth putting on Wikipedia, except maybe as an entry in Wiktionary. Primefac (talk) 18:19, 6 October 2014 (UTC)

Star Wars contexts appear to include it as the name of a certain Jedi master and as a media industry term meaning loosely a linked series of products. Whatever Iain M banks does with the word is not relevant to physics either. — Cheers, Steelpillow (Talk) 18:30, 6 October 2014 (UTC)

See Brane cosmology. It is the same idea, but they use the words "brane" and "bulk" instead of "skein" and "hyperspace". JRSpriggs (talk) 00:25, 7 October 2014 (UTC)

One-electron universe

Hello. Could someone take a look at One-electron universe? An IP recently added a lot of material about the theories of Donald G Coyne, an adjunct prof. from UC Santa Cruz. Towards the end of the section, it devolved into some weirdness about the technological singularity and the future of the "human Internet" that was not supported by the sources. I removed the most obviously silly parts[1]. The sources themselves don't seem obviously bad, but I'm not a physicist, and I can't tell if it's just gaslighting, or if the whole section is crackpottery, or something in between. Thanks. Grayfell (talk) 07:59, 8 October 2014 (UTC)

An IP editor is tending to revert attempts to delete the Internet fruitloopery. Apart from that, the more serious question remains as to whether Coyne's theoretical position is independently verifiable and hence notable. Can anybody help there? — Cheers, Steelpillow (Talk) 10:30, 8 October 2014 (UTC)

Meanwhile I have now requested semi-protection against the IP's edit warring. — Cheers, Steelpillow (Talk) 11:48, 8 October 2014 (UTC)

I've semi-protected the page. The article in its present form looks like a WP:COATRACK for Coyne's theories: they should be split out into their own article, if they need keeping at all. -- The Anome (talk) 11:54, 8 October 2014 (UTC)

A Physicist in the house

The technology article Optical disk requires help from a physicist because it strays into the area of Physics on a few occasions with dubious (and possibly amusing) results. The first one I have tagged, and written about my concerns on the talk page. The second one I have also tagged, and it is located towards the bottom of the "History" sub-section. It reads: "For this purpose the 16 bit samples of the analog signal were taken at the rate of 44,100 samples per second which was obviously following the Nyquist Criteria." This is not at all obvious to me, and I studied Physics (about 30 years ago). In fact, I wouldn't be surprised if it was incorrect. I had thought that the selection of 44.1 kHz as the sampling rate was associated with minimizing aliasing. Could an editor with a more recent, and thorough knowledge of Physics take a look at this article, please? CaesarsPalaceDude (talk) 12:14, 8 October 2014 (UTC)

44.1 kHz is supposed to be a bit more than twice the maximum frequency that humans can hear. That's the nyquist criterion. But it's also true that it's "associated with minimizing aliasing". The nyquist criterion is always "associated with minimizing aliasing", that's where it comes from :-D --Steve (talk) 14:10, 8 October 2014 (UTC)

Brief clarification of sampling frequency now in the text. The reduction of aliasing distortion below audible levels is quite a complex subject so I have not added more. — Cheers, Steelpillow (Talk) 14:48, 8 October 2014 (UTC)

There's a (poorly cited) article on this frequency at 44,100 Hz. There is a more detailed explanation for the choice of 44,100 that involves the difference between NTSC and PAL sampling rates. 0x0077BE [^talk/_contrib] 15:30, 8 October 2014 (UTC)

Thankyou so much. Great work! CaesarsPalaceDude (talk) 07:29, 9 October 2014 (UTC)

Let us consider a split (no, not a fork) to create a decent and needed article on gamma decay

(I'm getting no feedback on TALK:gamma ray, so am crossposting here as RfC. It's a very odd situation.)

Gamma decay (which now redirects to a section of gamma ray) is a very important radioactive decay process, with many fine points and that subsumes the entire field of gamma spectroscopy-- a main topic in nuclear physics. Presently, however, because it has been incorporated in the gamma ray article as a source of gamma rays, the entire topic of gamma decay now exists (as such) only as a short subsection on gamma ray!

Imagine if such an important topic as beta decay existed only in Wikipedia as a small section of an article on "high speed electrons" (which could also be produced by accelerators and found in cosmic rays). That would not be good, would it?

Per WP:SS we need a long stand-alone article on gamma decay. The subsection on gamma ray can be left or shortened a bit, and "gamma decay" can be the "main article" for it. The gamma decay article can be lengthened with more data, and also some of the material from nuclear isomer article, which in some sense stands in for it, on Wikipedia now (most of the gamma decay info is actually HERE). But that's also not right. Most gamma decay does not take place from nuclear isomers. It happens immediately (within 10^-12 sec) and doesn't deserve to be ignored for the sake of a few sexier nuclides that gamma decay slowly enough to have measurable half lives and act like other familiar radioactive decay.

I volunteer to start this thing. But I'm no expert on gamma decay, and it's going to have to serve as a "seed" article that will be allowed to let grow, and not have somebody decide that it needs to disappear and be shoe-horned into here, again. It's an important topic in any encyclopedia. Except this one. We need to recognize that, and create it and then leave it alone until it takes its rightful place. SBHarris 05:50, 2 October 2014 (UTC)

I'm not sure this warrants a separate article, but I'll defer to the particle physicists in the audience. Gamma radiation is effectively a fluorescence process by which particles relax to a lower-energy state by the emission of high-energy photons. It's qualitatively different from alpha and beta decay processes, which are fission processes that result in the transformation from one nucleus to another. I'm not really sure what would distinguish it from standard fluorescence other than the energy scale. 0x0077BE [^talk/_contrib] 02:01, 9 October 2014 (UTC)

Well, quantity has a quality all its own, as Napoleon liked to say. We have an article, after all, on internal conversion which competes with gamma decay in spinless nuclei, and also leaves them untransformed. As does internal pair production (no article yet). And the narrowness of the gamma linewidth allows Mossbauer spectroscopy. Also, the mechanics of the nucleus are difficult enough that they make optical fluorescence effects from electronic transitions in molecules look very simple.SBHarris 02:37, 9 October 2014 (UTC)

I am not a particle physicist, but I believe it should be a separate article on gamma decay.--Ymblanter (talk) 10:59, 9 October 2014 (UTC)

Or big rival Britannica distinguishes "gamma decay" from "gamma emission", with the former including the latter, but also internal conversion and internal pair production. In principle having a separate article seems like a good idea. This could either be a separate article on gamma emission or a more general article on "gamma decay" that covers "gamma emission", internal conversion and internal pair production. I think the latter may be the better option.TR 13:58, 9 October 2014 (UTC)

I'd be for a separate article on gamma decay / emission / processes. Seems warranted given the importance. Similar to how we have articles on both beta particle and beta decay. Headbomb {talk / contribs / physics / books} 15:14, 9 October 2014 (UTC)

Patchy particles

Dear physics experts: I came across an old AfC submission, Wikipedia talk:Articles for creation/Patchy Particle, that will soon be deleted as a stale draft. It appears to be about the same topic as Patchy particles, but the information and description of the subject is quite different. Is there anything that should be merged from the draft into the mainspace article? —Anne Delong (talk) 04:33, 11 October 2014 (UTC)

It looks like the article (particles) is just a list of different forms, whereas the draft (particle) actually talks about how they are formed (albeit not very well). The draft (specifically the last two paragraphs) should be merged into the article as a new section after cleanup. Unfortunately I'm fairly busy at the moment so I can't take care of it myself. Primefac (talk) 09:27, 11 October 2014 (UTC)

The discussion has moved to Talk:Patchy particles. —Anne Delong (talk) 13:17, 13 October 2014 (UTC)

Give us an opinion

This is getting a bit out of control Wikipedia:Articles for deletion/Universal rotation curve.

jps (talk) 19:23, 16 October 2014 (UTC)

Wikipedia talk:Articles for creation/Angular Propulsion

Dear physics experts: Here's another of these old AfC submissions that will soon be deleted as a stale draft. Is this a notable subject, and should the article be kept and improved? —Anne Delong (talk) 00:06, 22 October 2014 (UTC)

Donation of images for electromagnetism articles

Simulated electric field at 900 MHz (animated by phase) around a printed inverted-F antenna.

Multipaction within the gap inside a coaxial connector, driven by fields between the conductors. Color represents electron energy

(Cross-posted to Wikipedia talk:WikiProject Electrical engineering)

Hello everyone. I'm Stephen Murray, the Technical Writer for Computer Simulation Technology, who focus on electromagnetic simulation tools. One thing that we have recently realized is that we currently have quite a few example images/simulation models which illustrate devices and physical phenomena that Wikipedia doesn't currently have. Chiefly, these consist of various models of antennas, microwave filters and waveguide components, particle accelerator components and some nano-optical/photonic devices. We would like to donate images where we can in order to improve Wikipedia's coverage of these topics.

On the right are a couple of example pictures from our selection (illustrating microstrip antenna and multipactor effect respectively) - would these be helpful to the project? Because we have the simulation models, it would take relatively little effort on my end to adjust the angle of view or the field display. It's just a question of how to make these images as useful to the encyclopedia as possible. Any comments or suggestions would therefore be appreciated. Stephen Murray at CST (talk) 13:18, 28 October 2014 (UTC)

That is a generous offer. However, Wikipedia requires reliable secondary sources. You would be, I think, a primary source. Unless the images can be verified by a reliable secondary source, they should not be used. Constant314 (talk) 21:56, 28 October 2014 (UTC)

Constant314, creating an image that shows a phenomenon may be a primary source, but it sure can be helpful. I disagree completely with your assessment that any images created by Mr Murray are automatically invalid, and I'm guessing others in this project would back me up. Primefac (talk) 22:11, 28 October 2014 (UTC)

Not automatically invalid. I'm sure that some simulations can be shown to agree with depictions in secondary sources.Constant314 (talk) 23:07, 28 October 2014 (UTC)

Thanks for the comments, Constant314. For the antenna pictures, I can certainly easily cite the software tools and papers that were used to create and validate the antenna models. For the multipaction picture, I can show that it fulfills the criteria set out on the multipaction page (electrons in resonance with an oscillating field, causing secondary emission and resulting in exponentially-increasing electron production). Would this be adequate? Stephen Murray at CST (talk) 09:51, 29 October 2014 (UTC)

For example, in Antenna Theory by Balanis in chapter 1 there are intricate drawings of the electric field around a dipole antenna showing the development by 1/8’s of cycle. A simulation that filled in the gaps would likely be suitable. What I do not want to see is a bunch of new content with the justification “This is right because my simulator says so.” Constant314 (talk) 23:54, 29 October 2014 (UTC)

As long as you're illustrating content, that is already part of an article, there's no need to provide additional sources at all in my opinion (as those sources should already be mentioned in the accompanying text). If you introduce new content into the article that was not described in the text so far, the sources have to be supplied. As a rule of thumb: If you can contribute additional useful sources they are always welcome! --Patrick87 (talk) 11:07, 29 October 2014 (UTC)

These look nice to me (though I'm not familiar with the specific subject matter well enough to know where to put them), but I'm a bit confused about the time axis in the microstrip antenna. Why is the field varying with time? Does it represent the time-domain E-field, slowed down/aliased so that we are seeing the E-field as a function of time over the course of a repeating period of the wave? It says that it's tuned to 900 MHz, but maybe you can clarify that in the description. 0x0077BE [^talk/_contrib] 14:07, 28 October 2014 (UTC)

Thanks for the comment, I've tried to explain in the caption better. Stephen Murray at CST (talk) 14:29, 28 October 2014 (UTC)

As far as I'm concerned, these are great and you should feel welcome and encouraged to add pictures into articles wherever you think they are appropriate. If you have good judgment and add images where they are helpful and on-topic and educational, I doubt anyone will be upset about that. --Steve (talk) 20:13, 28 October 2014 (UTC)

Great, thank you very much.--Ymblanter (talk) 21:10, 28 October 2014 (UTC)

References

Have you considered the Wikimedia Commons?

Hi Stephen, that is a very kind offer. The Wikimedia Foundation, who own and host Wikipedia, have a separate repository for media files called the Wikimedia Commons. Images uploaded there can be included in Wikipedia articles in the usual way and appear for practical purposes as native images on Wikipedia. More significantly, they are similarly made available to the many foreign-language Wikipedias and other projects of the Foundation, making multiple uploads to different sites unnecessary.

Commons uploads are free of the "reliable sourcing" issues, discussed above, which dog the encyclopedia itself. Once images are on the Commons, the encyclopedia editors can discuss at their leisure which to include in an article and what to say about it.

Can I therefore ask your company to consider donating these images to the Wikimedia Commons? Its home page is at https://commons.wikimedia.org/wiki/Main_Page

If you do choose to upload, to either here or the Commons, perhaps you might like to update this conversation to point us to them.

You will still need to define the licensing terms under which you release each image. For example you can credit your company with the copyright. But if you want to restrict commercial re-use of the images then Wikipedia allows this kind of non-commercial license to some extent while the Commons does not, so Wikipedia would be the better bet after all. You can find out more at Wikipedia:Copyrights and Commons:Licensing. If you get confused about the options available (and not all licenses are compatible with the Commons), feel free to drop me a line on my talk page here - see link in my sig - or my equivalent discussion page on the Commons. — Cheers, Steelpillow (Talk) 10:36, 30 October 2014 (UTC)

Don't worry, I know about Commons! The two test pictures have both been uploaded to there, and it's where I intend to upload other images as well. Stephen Murray at CST (talk) 15:16, 30 October 2014 (UTC)