User talk:Nanite

Thanks for your contributions!

Hello, Nanite, and welcome to Wikipedia! I would give you the usual welcome spiel but it looks like you've got just about everything figured out. The diagrams in particular look very nice; I usually use Inkscape but its formula support is pretty bad -- I guess I should check out lpe. Keep up the good work and let me know if you have any questions. Cheers, a13ean (talk) 21:47, 3 June 2013 (UTC)

Yes, Ipe is my favourite. I have to admit it's a bit awkward to work with at times due to partial gui support, but if you like LaTeX then you can get along with its idiosyncrasies. :) --Nanite (talk) 21:54, 3 June 2013 (UTC)

Derivation starting with grand canonical ensemble

What is your source for the derivation in the section Derivation starting with grand canonical ensemble, i.e. the part beginning with "Due to the non-interacting quality...", and ending with "...and thus gives the exact Fermi-Dirac distribution for the entire state of the system"? Regards, --Bob K31416 (talk) 01:39, 11 June 2013 (UTC)

I admit I didn't look it up and just derived it myself, as I thought it was a pretty straightforward derivation. I mainly wanted to clean up some of the mess on the page with the previously posted derivations. I looked around and I found some other instances of the grand canonical approach (e.g., the first section of chapter 6 of Statistical Mechanics by R. K. SRIVASTAVA, J. ASHOK[1])... I'll add that book as a citation. --Nanite (talk) 13:36, 11 June 2013 (UTC)

Derivations starting with canonical distribution

In the section Derivations starting with canonical distribution, what is your source for the statement, "The reason for the inaccuracy is that the total number of fermions is conserved in the canonical ensemble, which contradicts the implication in Fermi–Dirac statistics that each energy level is filled independently from the others (which would require the number of particles to be flexible)"? Regards, --Bob K31416 (talk) 15:57, 11 June 2013 (UTC)

Well, good point, perhaps it's not stated quite precisely enough. A better way to state it might be something like "By the equivalence of ensembles in the thermodynamic limit,[cite any statmech book for this equivalence principle] the canonical ensemble is guaranteed to yield the same distribution as the result above, in the limit of a large number of particles. Indeed, as shown in the below derivations, once one makes the approximation of a large particle number they arrive at the Fermi-Dirac distribution. For small particle number, however, the Fermi-Dirac statistics are not exactly derivable from the canonical ensemble." --Nanite (talk) 13:57, 12 June 2013 (UTC)

Note that the derivation using the grand canonical distribution, involves essentially the same approximation as the derivation using the canonical distribution, because that is how the grand canonical distribution was derived. See Eqs. 4.4 and 4.21 in Srivastava & Ashok, which use Taylor expansions only up to the linear terms. --Bob K31416 (talk) 23:48, 12 June 2013 (UTC)

Sort of yes and sort of no. It's true that to have continuous parameters of temperature and chemical potential we need a big reservoir to supply energy and particles, respectively. In that sense, both the canonical ensemble and grand canonical ensemble are thermodynamic-limit approximations because they invoke a reservoir. On the other hand, I can still use the canonical ensemble to describe the probability distribution for a tiny finite system with only two energy states (e.g., a spin-1/2 paramagnetic impurity). In the same way I'd want to use grand canonical ensemble for a tiny system where states of different particle number are accessible, like electrons in a small capacitor or in an ionizable molecule.

If I wanted to compute the statistics of a noninteracting fermion system with, say, only four available single-particle states, I'll still get exactly Fermi-Dirac statistics if I use GCE; alternatively I can use CE with a large particle reservoir attached, however that would essentially involve rederiving GCE along the way. What wouldn't work is to use the CE for the finite system alone (fixing the number of particles in the finite system). --Nanite (talk) 09:24, 13 June 2013 (UTC)

Seems like you didn't understand my last message. No matter. Per WP:V, any claim that the derivation using the grand canonical distribution is exact, and any implication resulting from that claim, such as that the derivation using the grand canonical distribution is more exact than the derivation using the canonical distribution, will be removed or rewritten because it is unsourced. --Bob K31416 (talk) 11:39, 13 June 2013 (UTC)

Well, google books isn't letting me look at that chapter of the Srivastava book, so I'll have to refer you to another one, Kershon Huang's "Statistical mechanics" (2nd edition, 1987). (One could possibly find an online copy of it by searching for Huang, K. Statistical mechanics djvu, but that might be illegal to obtain if you don't own a physical copy.). Anyhow, the grand canonical ensemble for sure does get derived with a large number approximation (for a total system composed of large reservoir plus subsystem), but that approximation is taken only for the reservoir (critically, equation 7.30 and 7.33 assume very large reservoir). Nothing is assumed for the subsystem. That's why the final result is the exact probability distribution for the state of the subsystem, whether the subsystem is very large or finite. Note that the canonical ensemble can only be derived using a very similar approximation for a large heat reservoir (the critical approximation is made in Huang's equation 7.3, regarding reservoir entropy). Again, it too applies for finite subsystems.

Given that the grand canonical ensemble gives the exact probability distribution for any system (small or large) which is in equilibrium for exchange of particles and energy with an ideal reservoir (reservoir with fixed chemical potential and temperature), the two-line quickie derivation of Fermi-Dirac statistics inherits that exactness. Anyway, go ahead and make the changes you want to make. --Nanite (talk) 14:28, 13 June 2013 (UTC)

Fermi energy

Since the changes you made to the first paragraph of Fermi energy do not correspond to either textbook definitions or the IUPAC definition (see thread: WT:PHYSICS#Fermi energy), I would be grateful if you would now revert them. Jheald (talk) 09:12, 26 June 2013 (UTC)

Fermi level

You provided a reference to the statement: "if a voltmeter is attached to the junction, one simply measures zero" (Page 404 of Sah, Chih-Tang (1991). Fundamentals of Solid-State Electronics. World Scientific. ISBN 9810206372). However, that statement is wrong, and one simply DOES NOT measure zero there. I haven't had access to that reference but, with a p-n junction, there is an internal potential which is caused by the workfunction difference between the n-type and p-type semiconductors. This potential equals the built-in potential (which is typically about 0.7 volts for silicon at room temp). The built-in potential is explained in Wikipedia's article on "p–n junction" and I use that as a reference. Also, please see http://ecee.colorado.edu/~bart/book/book/chapter4/ch4_2.htm#4_2_3 . Also, I just measured the voltage of several p–n junctions myself using an actual modern digital voltmeter, and none is zero (thermocouple effects are cancelled due to the symmetry of the contact electrode materials used and constant temperature) and they are very close to the calculated voltages. So please eliminate that false statement or correct it accordingly. Thank you.

98.217.147.183 (talk) 18:37, 15 August 2013 (UTC)

Was your voltmeter in volts mode (applying zero current), or was it in diode mode (applying nonzero current)? I tried this test as well just now and I measure less than 1 mV (0 within error) on a silicon PN junction diode, using a modern digital multimeter in DC volts mode (the multimeter has an input impedance of around 10 Mohm, for what it is worth). Actually you can see even in the link you provided, that the applied voltage V_a is defined as the difference between Fermi levels, divided by charge q (Fig. 4.2.4). When V_a is zero (zero applied voltage, i.e., neither forward or reverse bias), the situation is that in Fig. 4.2.3: a junction in thermal equilibrium with zero current. If you insist to think about things in terms of Galvani potentials, remember that there are also built-in potentials at the metal-semiconductor and semiconductor-metal junctions around the diode. --Nanite (talk) 20:35, 15 August 2013 (UTC)

My voltmeter was in volts mode (applying zero current). Your problem with your test is that you used a voltmeter with an input impedance of only around 10 Mohm (a so called low cost multimeter). Either use a high impedance voltmeter or a larger size p-n junction, such as a large photodiode or a photoelectric cell. And yes, the diode would be performing work in our non-infinite impedance voltmeters (unless you have it at absolute zero) - (think Peltier, photovoltaic effects, etc.) The cooler and smaller the junction, the higher the voltmeter impedance needed to sense the built-in potential. Again, the potentials at the metal-semiconductor and semiconductor-metal junctions around our diodes were cancelled out due to the symmetry of the contact electrode materials used, and fairly the same constant temperature of the junctions. The statement: "if a voltmeter is attached to the junction, one simply measures zero" in the article is incorrect. The measurements are very close to the calculated voltages. So please eliminate that false statement or correct it accordingly. Thank you.

98.217.147.183 (talk) 11:57, 26 September 2013 (UTC)

Sketch of band diagram for a pn diode at equilibrium including metal-semiconductor junction, pn junction, and semiconductor-metal junction.

If you read up on Seebeck effect you'll find that it only occurs where there are temperature differences (regardless of whether one of the temperatures is zero). That is a non-equilibrium situation, as is the case of the photovoltaic effect. If you are measuring a nonzero voltage with a voltmeter, then the part is out of equilibrium for some reason (input bias current of voltmeter, temperature differences, light shining on, etc.). Let me know which model of voltmeter you're using, and which kind of diode you're measuring, under what conditions, and we can figure this out.

By the way, the semiconductor-metal junctions in a pn diode are usually very unsymmetrical (but it doesn't matter for equilibrium: the Fermi level is constant throughout). I think it's worth pointing out Herbert Kroemer's rule: "If, in discussing a semiconductor problem, you cannot draw an Energy Band Diagram, this shows that you don't know what you are talking about." Try to draw a band diagram for the pn diode at equilibrium including metal leads and see whether you can make a different voltage - in any sense - between the metal leads. I've included my own. --Nanite (talk) 20:55, 26 September 2013 (UTC)

(edit conflict) Voltmeters have large but finite internal resistances. You can't measure the built-in potential of a diode with one. If you could, that would violate energy conservation since a diode would be performing work. a13ean (talk) 20:35, 15 August 2013 (UTC)

Yep, what Nanite said. The diode test mode flows a current -- you couldn't do this with a galvanometer-type voltmeter for example. a13ean (talk)

Maxwell–Jüttner distribution

In Maxwell–Jüttner distribution, some concerns about adherence to standard Wikipedia conventions and standard conventions of TeX usage arise:

• I presume Maxwell is James Clerk Maxwell, but the article doesn't say so, and doesn't say who Jüttner is. Those should be mentioned.
• It is not correct to write mc². Rather, it should say mc². One italicizes variables, but not digits and not parentheses or the like. This is consistent with TeX and MathJax usage, and is codified in WP:MOSMATH. I fixed this.
• Although you've got Maxwell–Jüttner and Maxwell–Boltzmann with an en-dash, later you have Fermi-Dirac and Bose-Einstein with a hyphen rather than an en-dash. I corrected this.
• Don't write \mathrm{exp}. Instead, write \exp. (And similarly with \log, \sin, \arctan, \max, \det, etc.) Contrast these:

a\mathrm{exp}b yields $a\mathrm {exp} b\,$

a\exp b yields $a\exp b\,$

The second form automatically provides proper spacing; the first does not. I changed this.

Michael Hardy (talk) 13:36, 13 September 2013 (UTC)

Thanks for correcting the errors (I just copied the text from the MB distribution page and didn't pay much attention to the exact typesetting from the previous writers). --Nanite (talk) 13:44, 13 September 2013 (UTC)

Thermal transpiration

Thanks for contributing the new article Thermal transpiration. However, one of Wikipedia's core policies is that material must be verifiable by being clearly attributed to reliable sources. Please help by adding sources to the article you created and by making it clear how the sources support the material. See here for how to do inline referencing. Many thanks! PS If you need any help, you can look at Help:Contents/Editing Wikipedia or ask at Wikipedia:New contributors' help page, or just ask me. ErikHaugen (talk | contribs) 19:01, 4 December 2013 (UTC)

And thanks for adding some! ErikHaugen (talk | contribs) 18:26, 30 December 2013 (UTC)

Articles on technical topics

Nanite, thanks for your article Thermal transpiration. Writing an article about a technical topic for a general audience is, needless to say, but one thing that helps is to include a section on practical applications. Is thermal transpiration an important part of any consumer products or manufacturing? I feel this would greatly help the article. Ego White Tray (talk) 04:40, 30 December 2013 (UTC)

Nonrectifying junction

Metal–semiconductor junction says "M–S junctions can either be rectifying or non-rectifying. The rectifying metal–semiconductor junction forms a Schottky barrier, making a device known as a Schottky diode, while the non-rectifying junction is called an ohmic contact." Non-rectifying junction redirects to ohmic contact, but that article doesn't define the term, after this edit you made. Can you update the ohmic contact article to define the term non-rectifying junction and contrast it with ohmic contact since I believe you mean that the terms are not equivalent. I take it that there is a difference between a metal–semiconductor ohmic contact and a generic ohmic contact. Or maybe nonrectifying junction should redirect to Metal–semiconductor junction if it only applies to those. I'm not a physicist, and physics was not my best subject in school, so I defer to you. Thanks, Wbm1058 (talk) 17:23, 16 January 2014 (UTC)

Ah, my bad. I didn't realize nonrectifying junction linked to there as well, and it's a good point to emphasize that the article is mainly about semiconductors. The lead should be better now, let me know what you think. Nanite (talk) 18:31, 16 January 2014 (UTC)

Thanks, that seems better. See also electrical junction, that might benefit from an expert's attention too. Wbm1058 (talk) 19:50, 16 January 2014 (UTC)

Help with Criticality article

Hello Nanite, I see you have done some work on the Criticality Accident article. Could you please have a look at my proposal for a definition of Criticality? Thanks!--Graham Proud (talk) 04:09, 3 February 2014 (UTC)

On Wikiversity

I thought I would go off the subject of our discussion of Gibbs paradox. I am an ex plasma physicist who left Solid State physics in my first year of graduate school because the theory seemed incomprehensible. For example, where was the proof that electrons accelerated according to their 'effective mass' when subjected to an electric field? (I now understand that the proof almost certainly exists somewhere, but an introductory book (e.g. Kittel) had no space to fill in every little detail).

You can do original research on Wikiversity. It is a very quiet and obscure place where you can tinker around with ideas for articles. Your thoughts on Gibbs paradox are in a somewhat obscure place in Wikversity (obscure²!) Someday, Wikipedia will have a good (or at least mediocre) article on every possible subject. Talented writers with offbeat ideas will have nowhere else to write than places like Wikiversity.--guyvan52 (talk) 02:36, 18 February 2014 (UTC)

thermocouples_reference patches

Hi Nanite,

I have a couple minor patches I would like to submit to your thermocouples_reference python module. Since I couldn't find a better way of getting in touch with you, they are pasted below. The first one allows the module to work under python 2.6. The second fixes an error in inverse_CmV when Tstart is not None.

Thanks, David Irving dhirving@gmail.com

(((SNIP)))[2]

Hi David, thanks for the contribution! I incorporated your changes more or less and I'll put out a new version soon.

I'm glad to hear someone is using the module. In case you find any more bugs, I created a github repository, though feel free to poke me here again.

--Nanite (talk) 21:01, 21 July 2014 (UTC)

Open statistical ensemble

Hi Nanite,

The article "Open statistical ensemble" is very important although this issue has not been discussed in the literature. The fact that the grand canonical ensemble has a significant drawback - a fictitious surface at the boundary of the volume inherited from the canonical ensemble. Look a little new subsection in the GCE. Luksaz (talk) 21:20, 30 November 2014 (UTC)

ArbCom elections are now open!

Hi,
You appear to be eligible to vote in the current Arbitration Committee election. The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to enact binding solutions for disputes between editors, primarily related to serious behavioural issues that the community has been unable to resolve. This includes the ability to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail. If you wish to participate, you are welcome to review the candidates' statements and submit your choices on the voting page. For the Election committee, MediaWiki message delivery (talk) 12:58, 23 November 2015 (UTC)

Spatial dispersion

Hi, thank you for starting the Spatial dispersion page. I will try to add some relevant points, citations and cross-link t with the metamaterial articles etc. FDominec (talk) 08:44, 7 December 2015 (UTC)

Fortifying wikiquanta

Hi, I seek volunteers for this. Boris Tsirelson (talk) 17:58, 15 April 2016 (UTC)

Hi @Tsirel: thanks for the invitation but I'll have to pass. I too am not an expert in quantum information. Best of luck. Nanite (talk) 18:11, 15 April 2016 (UTC)

Lauren Southern

Notability, for Wikipedia's purposes, can be especially tricky when it comes to broadcast or print journalists. The fact that a viewer or reader can see their name and face by watching or reading the very same media outlets we might be using as sources certainly looks, from a reader's perspective, like the journalist should be considered notable — however, notability for our purposes is not determined by the simple fact of being able to verify that the topic exists.

A journalist has to be the subject of reliable source coverage about her, in media outlets other than her own employer, to qualify for a Wikipedia article, and does not get to keep an article whose only source is her own "our staff" profile on the website of her own employer — but a staff profile was the only sourcing that existed in Southern's article, and the article in fact was just a thinly-veiled rewrite of that same profile, and that's exactly the kind of article that a journalist does not get to keep on here.

For far more journalists than you might think, staff profiles are actually the only possible sources out there, so an article about them can't actually stand until they accomplish something more than just being a working journalist — Dawna Friesen, for example, didn't have a keepable article until she became the anchor of Global National in 2010 even though she'd already been a reporter for many years before that, and John Ibbitson didn't have a keepable article until we started being able to source him over WP:AUTHOR for books he was publishing separately from his work with The Globe and Mail itself. And they're two of the most famous journalists in all of Canada. Conversely, we just AFDed an article about Elizabeth Renzetti, a colleague of Ibbitson's at the Globe who couldn't be sourced to the same degree as Ibbitson can — RS coverage about her doesn't exist to the same degree, so her article was much more purely dependent on primary sourcing (the article's only cited source, in fact, was a generic "Biographical information from the Globe and Mail, Toronto, Ontario, Canada and from www.elizabethrenzetti.com." line), and on a database search I landed a lot of hits where she was the bylined author of the content but none where she was the subject. So that simply wasn't able to stand.

The deletion also does not mean that nobody is ever allowed to recreate an article about her again — if somebody in the future can do better than the first version, and can bring stronger, more independent sourcing to support it, then they are allowed to try again. Bearcat (talk) 14:35, 23 April 2016 (UTC)

@Bearcat: Ah OK, I can't see the deleted article so I could only guess what was there beforehand. Thanks for the long explanation! I think I understand the situation and the speedy deletion makes sense, no complaints here.

Definitely it makes sense a working journalist doesn't deserve WP article, they're not really a public person anymore than a scientist. They just do their job and their name appears as author. However in Lauren's case I don't think she could be called a working journalist. At a rough glance she is splitting her time between editorializing on Rebel Media and social media activism. (Actually I was not aware of the former aspect, previously I only knew of her through her activism role.) Also she had a hand in politics as a candidate for the Libertarian party.

At this time her notability is arguably borderline, yet I have a strong feeling she is on the rise as an icon of the alt-right and before long she'll definitely be past the threshold. I am a bit inclined to recreate the article but of course there's no rush.

There is now some biographical information that can be gleaned in news articles, like the pee-on-head ones that came out recently: ( [3], [4] ). What do you think? --Nanite (talk) 18:04, 23 April 2016 (UTC)

ArbCom Elections 2016: Voting now open!

Hello, Nanite. Voting in the 2016 Arbitration Committee elections is open from Monday, 00:00, 21 November through Sunday, 23:59, 4 December to all unblocked users who have registered an account before Wednesday, 00:00, 28 October 2016 and have made at least 150 mainspace edits before Sunday, 00:00, 1 November 2016.

The Arbitration Committee is the panel of editors responsible for conducting the Wikipedia arbitration process. It has the authority to impose binding solutions to disputes between editors, primarily for serious conduct disputes the community has been unable to resolve. This includes the authority to impose site bans, topic bans, editing restrictions, and other measures needed to maintain our editing environment. The arbitration policy describes the Committee's roles and responsibilities in greater detail.

If you wish to participate in the 2016 election, please review the candidates' statements and submit your choices on the voting page. MediaWiki message delivery (talk) 22:08, 21 November 2016 (UTC)

Why remove the section about Toby Turner rape allegations?

I understand their just allegations and may not be true but I'm pretty sure it's still relevant to have it there. If not can you explain why it's not?

Destroyedsoul (talk) 05:14, 24 November 2016 (UTC)Destroyedsoul

@Destroyedsoul: Hi, you might have missed the explanation I left on Talk:Toby_Turner#Remove_abuse_allegations.3F. I am by no means certain on this, but I think the idea is that it's better to err on the side of omission when BLP criminal allegations are concerned. --Nanite (talk) 09:39, 25 November 2016 (UTC)

Pizzagate

Please see the extensive discussions on the article talk page, BLP noticeboard and elsewhere; there is both widespread consensus and policy support for clearly and directly stating the falsity of the claims involved in that matter. NorthBySouthBaranof (talk) 09:05, 7 December 2016 (UTC)

@NorthBySouthBaranof: My apologies, I didn't expect there could possibly be a huge discussion on this word "false" and so I didn't check the talk page. I agree it's false but I think it's silly to include that word. On this point I will leave a comment on the Talk:Pizzagate page where others can find it. --Nanite (talk) 10:38, 7 December 2016 (UTC)

[5]

I suggest to WP:DENY. Arguing with a troll is like wrestling in the mud with a pig. Tigraan^{Click here to contact me} 11:51, 9 December 2016 (UTC)

@Tigraan: I suspect our friend is less of a troll and more of an alienated Russian academic who doesn't understand that WP isn't for self promotion...but either way I couldn't resist a joke about underpants. ;-) --Nanite (talk) 16:12, 9 December 2016 (UTC)

Well, if you like it, go ahead. (I admit "troll" was probably a bit over the top.) Tigraan^{Click here to contact me} 16:39, 9 December 2016 (UTC)

References

Remember that when adding content about health, please only use high-quality reliable sources as references. We typically use review articles, major textbooks and position statements of national or international organizations (There are several kinds of sources that discuss health: here is how the community classifies them and uses them). WP:MEDHOW walks you through editing step by step. A list of resources to help edit health content can be found here. The edit box has a built-in citation tool to easily format references based on the PMID or ISBN. We also provide style advice about the structure and content of medicine-related encyclopedia articles. The welcome page is another good place to learn about editing the encyclopedia. If you have any questions, please feel free to drop me a note. Jytdog (talk) 06:04, 9 August 2017 (UTC)

Socking

Are you editing logged out[6]? Alexbrn (talk) 15:07, 9 August 2017 (UTC)

Please answer that. Thanks. Jytdog (talk) 16:12, 9 August 2017 (UTC)

@Jytdog:@Alexbrn: Why the heck do you think you guys are entitled to know whether I'm editing while logged out?

And why are you guys ripping out valid primary and secondary sources? This is extremely frustrating. --Nanite (talk) 16:48, 9 August 2017 (UTC)

Because if you are editing logged-out it's a kind of socking, and you need sanctioning. No answer yet I see. Alexbrn (talk) 18:00, 9 August 2017 (UTC)

This is ridiculous. Stop harrassing me and threatening me with sanctions. See WP:HUSH and WP:SOCKOPHOBIA. --Nanite (talk) 18:07, 9 August 2017 (UTC)

So were you editing logged-out? It's a very simple question? Alexbrn (talk) 18:15, 9 August 2017 (UTC)

I have no obligation to answer that question. Please leave me alone. --Nanite (talk) 18:18, 9 August 2017 (UTC)

To be clear if you are logging out to edit war, that is a violation of SOCK. This the courteous way to handle the concern.Jytdog (talk) 18:35, 9 August 2017 (UTC)

@Alexbrn:@Jytdog: regardless of what I answer, you wouldn't believe me. By the way, the courteous way to handle this would have been "Hey, I am slightly worried that you're editing logged out. If so, please see policy X and Y. If I'm mistaken, I apologise for the suspicion!" instead of trying to find out a user's IP address. --Nanite (talk) 19:06, 9 August 2017 (UTC)

Why wouldn't anyone believe you? What's the answer? - I will take it in good faith! Alexbrn (talk) 19:35, 9 August 2017 (UTC)

Haven't you heard the story of the two brothers - one always tells the truth and the other always tells lies. What question must you ask to get the truth? Roberttherambler (talk) 20:57, 9 August 2017 (UTC)

If you think there is a possibility of sockpuppetry, start a sockpuppet investigation. Otherwise it is counterproductive to have any discussion here about it.--Tosiaki! (talk) 21:59, 9 August 2017 (UTC)

Edit war warning

Your recent editing history at Neuroticism shows that you are currently engaged in an edit war. To resolve the content dispute, please do not revert or change the edits of others when you are reverted. Instead of reverting, please use the talk page to work toward making a version that represents consensus among editors. The best practice at this stage is to discuss, not edit-war. See BRD for how this is done. If discussions reach an impasse, you can then post a request for help at a relevant noticeboard or seek dispute resolution. In some cases, you may wish to request temporary page protection.

Being involved in an edit war can result in your being blocked from editing—especially if you violate the three-revert rule, which states that an editor must not perform more than three reverts on a single page within a 24-hour period. Undoing another editor's work—whether in whole or in part, whether involving the same or different material each time—counts as a revert. Also keep in mind that while violating the three-revert rule often leads to a block, you can still be blocked for edit warring—even if you don't violate the three-revert rule—should your behavior indicate that you intend to continue reverting repeatedly. Jytdog (talk) 16:13, 9 August 2017 (UTC)

I'm going to keep this on my talk page because it's part of a funny story. Have you ever had an edit war that was so notorious it got reported in the media? In two different places? Well, I have! [7] [8] (And it wasn't even a good edit war :D )--Nanite (talk) 08:38, 20 August 2017 (UTC)

Just letting you know that

There's an article in Breitbart "Wikipedia’s Left-Wing Editors Attempt to Minimize Evidence Supporting Google Memo" that mentions your user name as well as User:NorthBySouthBaranof and User:Jytdog, purportedly written by User:The Devil's Advocate. I'm just letting you know that this has been published, but if there is anything I can do to help, e.g. if you view the article as harassment, please let me know.

Sincerely, Smallbones_(smalltalk) 14:32, 15 August 2017 (UTC)

Whoops! I see from ANI that you've already been pinged on this. Smallbones_(smalltalk) 14:34, 15 August 2017 (UTC)

Onion urls

Thanks for digging up some onion urls, but given there's no authority for them and they're highly subject to hijacking, phishing, etc. we really do need a very solid source to include them anywhere. IMO WP:EL makes most any onion link problematic, but I think there's still consensus to include when we have good sourcing. — Rhododendrites ^talk \\ 04:48, 23 August 2017 (UTC)

@Rhododendrites: No worries, I get ya. Just want to say one thing: my plan was to only add defunct links based on unreliable sources. What do you think of https://www.gwern.net/DNM%20survival by the way? --Nanite (talk) 04:51, 23 August 2017 (UTC)

Only a little bit familiar with the site. Not ideal, but probably good enough. That said, wouldn't a defunct site's url be at least somewhat likely to be hosting some other (potentially problematic) content now? I'm not sure what encyclopedic purpose it would serve? — Rhododendrites ^talk \\ 04:53, 23 August 2017 (UTC)

Rhododendrites, Hmm -- that's an interesting point that I hadn't considered. AFAIK it's difficult to replicate onion names in full as they're like crypto hashes. But they are short hashes, so maybe it's possible. Interestingly, I found one phish [9]. --Nanite (talk) 04:56, 23 August 2017 (UTC)

In case you are as nerdy as me: I got curious and yes, they're thought to be un-replicatable. Apparently when facebook started facebookcorewwwi.onion, a bunch of people were shocked that they got a full "vanity" address without garbage characters at the end[10][11]. They claimed they were just lucky to get one where the garbage characters were not too bad[12]. Calculations here say it would take billions of dollars (and years of time) to duplicate an onion site. --Nanite (talk) 05:09, 23 August 2017 (UTC)

Hmmmm. Could've sworn I've seen domains (or, I guess, just urls) hijacked before, with some market or carding forum or something. It may be that it was hosted by a third party and someone got into the account with that third party or something, I guess? I've also seen a lot of "that one has been hacked, the new one is here" comments around these articles. I wouldn't claim to have any technical insight, though. — Rhododendrites ^talk \\ 05:24, 23 August 2017 (UTC)

Labels essay

Please see User talk:Nanite/Labels essay -- PBS (talk) 09:43, 24 August 2017 (UTC)

A barnstar for you!

	The Original Barnstar
	Thanks for diving in to improve Wikipedia's Tor-related articles! — Rhododendrites talk \\ 15:49, 1 September 2017 (UTC)

AfC

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Fine-structure constant & graphene

Dear Nanite,

On 27 May 2016 you modified Fine-structure_constant#Physical_interpretations note on graphene specifying that the absorption value for normal-incident light on graphene in vacuum would be given by ⁠πα/(1 + πα/2)²⁠ or 2.24%, and the transmission by ⁠1/(1 + πα/2)²⁠ or 97.75%.

I have found this optical transmittance value in Kuzmenko et al 2007 paper. But Nair et al 2008 paper indicates that graphene absorption (as a ratio of absorbed to incident energy) is πα not ⁠πα/(1 + πα/2)²⁠.

I would appreciate if you could explain how you derived this latter absorption value.

On a side note: shouldn't such defined values (along with reflectance) add to 100%? The reflectance would be then given by ⁠π²α²/4/(1 + πα/2)²⁠ or 0.013% (?).

--Guswen (talk) 19:52, 15 October 2020 (UTC)

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A barnstar for you!

	The Original Barnstar
	Your videos are beautiful (especially the one on Wigner functions). pony in a strange land (talk) 22:27, 3 September 2023 (UTC)

@Cosmia Nebula: Yes I like the Wigner one a lot, it is somehow mesmerizing. I just uploaded a higher res version to dazzle even more. --Nanite (talk) 04:18, 6 September 2023 (UTC)

I tried using your code for Wigner functions today. It seems some of the latest Python things broke parts of it. Specifically, the origin='lower left'. I also made a bit of minor improvements to create folders if none appears, and used matplotlib agg backend to prevent memory leak when run in a GUI.

The following works on Python 3.10.10:

"""
Quantum mixed state evolver, and wigner distribution plotter.
Basic strategy:
- Use a spatial finite-difference scheme with not too many pixels. Just
  enough that pixelization doesn't become an issue (i.e., at least a few points
  per wavelength), but not so much that it becomes ridiculously slow.
- Just use full eigen-decomposition of the hamiltonian, don't bother with any
  time-stepping stuff.
- Create a density matrix by statistically superimposing various gaussian wave
  packet pure-states.
- Calculate density matrix in energy basis at any time in future, easy since
  the evolution operator is diagonal in this basis.
- Convert to wigner distribution by:
  - first transforming to the position basis,
  - then using a fourier transform trick (wigner distribution is just fourier
    transform of the antidiagonals!)
"""
from pylab import *
import os
for dirname in ['schmidt', 'wigframes']:
    if not os.path.exists(dirname): os.makedirs(dirname)
import matplotlib as mpl
mpl.use('agg') # prevent memory leak when run in a GUI like Jupyter
rc('text', usetex=True) ; rc('savefig', dpi=300)
### Parameters
# Very important number, smaller means more classical (finer-spaced discrete levels, larger means more quantum (fewer discrete levels)
hbar = 0.10/(2*pi)
def potential(x):
    return x**6 + 4*x**3 - 5*x**2 - 4*x
# the position-space:
x = linspace(-0.4,1.4,751)
N = len(x)
dx = x[1] - x[0]
U = potential(x)
mass = 1.0
# As an optimization we will throw away all high-energy eigenstates. They are going to
# be trash due to high spatial frequency (so finite-difference momentum is not
# accurate), and they just slow things down.
eig_cutoff = 100
### Calculate the Hamiltonian H = U + hbar^2 (d/dx)^2/2m
# Potential energy goes on diagonal of hamitonian
H = diag(U)
# For the kinetic energy operator (-hbar^2/(2*m) * d^2/dx^2), the usual central difference
# approximation will be used. These go on diagonal and off-diagonals.
H.flat[0len(x)+1] += hbar*hbar/(mass*dx*dx) # on diagonal
H.flat[1len(x)+1] += -0.5*hbar*hbar/(mass*dx*dx) # upper diagonal
H.flat[len(x)len(x)+1] += -0.5*hbar*hbar/(mass*dx*dx) # lower diagonal
# Diagonalize the hamiltonian and cut off high energies
eigval, eigvec = eigh(H)
eigval = eigval[:eig_cutoff]
eigvec = eigvec[:,:eig_cutoff]
eigvec_H = conj(eigvec.T)
# This is basically the true hamiltonian we are going to model, with cutoff.
H_actual = eigvec @ diag(eigval) @ eigvec_H
### Prepare a density matrix (in energy eigenvector space) for time=0
rho_E = np.zeros((len(eigval), len(eigval)), dtype=complex)
# Use gaussian wavepacket pure states, then create a mixture with an uncertainty
# in the wavepacket position and momentum.
xwidth = sqrt(hbar)*0.33 ; countx = int(2 * 0.5 // xwidth)
pwidth = 0.5*hbar/xwidth ; county = int(2 * 2 // pwidth)
print(f"using {countx}*{county} wavepackets with sigma_x = {xwidth:.4f} and sigma_p = {pwidth:.4f}")
for x0 in linspace(0 + xwidth, 0.5 - xwidth, countx):
    for p0 in linspace(-1 + pwidth, 1 - pwidth, county):
        # make the packet and decompose it into eigenbasis
        packet = ((xwidth/dx)**2 * 2*pi)**(-0.25) * exp(-(x - x0)**2 / (2*xwidth)**2 + (1j * p0 / hbar)*x)
        decomp = eigvec_H @ packet
        # add it to matrix
        rho_E += decomp[:, None] * conj(decomp)
# normalize it
rho_E /= trace(rho_E)
assert np.all(rho_E == rho_E.T.conj()), "must be hermitian"
# It is straightforward to time-evolve rho_E
def rho_E_time(rho_E, t):
    # unitarily evolve the rho_E -- easy since it's the energy basis so
    # the unitary operator U = exp(-iHt/hbar) is diagonal.
    # rho(t) = U(t) rho(0) U(t)^h    so this is elementwise multiply by a phase shift.
    Ediff = eigval[:,None] - eigval
    return exp((-1j * t/hbar) * Ediff) * rho_E
# It's also straightforward to calculate rho_x (the position-basis density matrix).
def rho_x_from_E(rho_E):
    return eigvec @ rho_E @ eigvec_H
# Define some parameters of the wigner transform
wig_Np = int(1.5*N) # increase the ordinary momentum resolution by padding
wig_dp = hbar*pi/(dx*wig_Np) # p resolution
wig_p0 = -(wig_Np//2)*wig_dp
wig_extent = (x[0] - 0.5*dx,
              x[-1] + 0.5*dx,
              wig_p0 - 0.5*wig_dp,
              wig_p0 + (wig_Np + 0.5)*wig_dp)
def wignerify(rho_x):
    """ compute wigner transform of space-basis density matrix """
    # We want to FFT along the antidiagonals: [A] , [aBc], [bCd], and [D]
    # To do so we'll 'rotate the matrix' anticlockwise by 45 degrees
    #         ----        ----
    #        |Axax|      | ab |
    #        |xBxb|  --> |ABCD|
    #        |cxCx|      | cd |
    #        |xdxD|      |    |
    #         ----        ----
    # (this puts the diagonals onto rows)
    # The dropped 'x' elements contain mostly redundant information. They
    # could be included but that requires extra computation due to how they straddle
    # across the diagonal.
    Nx = len(rho_x)
    rhoflat = rho_x.ravel('C')
    rho_rot = np.zeros((Nx,Nx), dtype=complex, order='F')
    for i,row in enumerate(rho_rot):
        diagnum = (Nx - 1) // 2 - i
        if diagnum >= 0:
            row[diagnum:Nx-diagnum] = rhoflat[2*diagnum:Nx*(Nx+1-2*diagnum):Nx+1]
        else:
            row[-diagnum:Nx+diagnum] = rhoflat[-2*diagnum*NxNx+1]
    # Fourier transform along the columns.
    res = fft(rho_rot, n = wig_Np, axis=0)
    # deshift the Nx // 2
    res *= exp((2j*pi*(Nx//2)/wig_Np) *  arange(wig_Np)[:,None])
    # Since input rho_x was hermitian, the wigner transform has no imaginary part
    # aside from numerical errors.
    res = res.real
    # put 0 momentum in middle and then snip to size
    res = np.roll(res, wig_Np//2, axis=0)
    return (1./(pi * hbar)) * res
def wigplot(wigner):
    fig = figure(figsize=(4,3))
    ax = axes((0.06,0.07,0.87,0.86))
    ax.set_xlim(-0.20,1.38)
    ax.set_ylim(-3.4,3.4)
    ax.set_xticks([])
    ax.set_yticks([])
    ax.set_xlabel('position $x$')
    ax.set_ylabel('momentum $p$')
    ax.imshow(wigner,
              origin='lower', extent=wig_extent,
              aspect='auto', cmap = matplotlib.cm.RdBu,
              interpolation='bicubic',
              norm=matplotlib.colors.SymLogNorm(linthresh=0.2, linscale=0.5,
                                                vmin=-4, vmax=4),
              )
    # add a rectangle to represent area of hbar
    hbarx = sqrt(hbar) * 0.40
    hbary = hbar/hbarx
    ax.add_artist(Rectangle((-0.07,-3.3),
                  hbarx*sqrt(2*pi), hbary*sqrt(2*pi), facecolor=(0.6,0.85,0.6), edgecolor='k', linewidth=0.5, linestyle='--'))
    ax.text(-0.07-0.01, -3.3 + 0.5*hbary*sqrt(2*pi), r'$h = {}\quad$', ha='right', va='center')
    ax.add_artist(Rectangle((-0.07,-2.4),
                  hbarx, hbary, facecolor=(0.6,0.85,0.6), edgecolor='k', linewidth=0.5, linestyle='--'))
    ax.text(-0.07-0.01, -2.4 + 0.5*hbary, r'$\hbar = {}\quad$', ha='right', va='center')
    # draw marginal x- and p- probability distributions on edges of plot
    ax_Px = axes((0.06, 0.93, 0.87, 0.07))
    ax_Px.axis('off')
    ax_Px.set_xlim(*ax.get_xlim())
    ax_Px.set_ylim(0,5.4)
    Px = np.sum(wigner, axis=0) * wig_dp
    ax_Px.fill_between(x, 0, Px, facecolor='#1f77b4')
    ax_Pp = axes((0.93, 0.07, 0.07, 0.86))
    ax_Pp.axis('off')
    ax_Pp.set_ylim(*ax.get_ylim())
    ax_Pp.set_xlim(0,1.0)
    Py = np.sum(wigner, axis=1) * dx
    ax_Pp.fill_betweenx(wig_p0 + arange(len(Py))*wig_dp, 0, Py, facecolor='#1f77b4')
    return fig, ax
def entropy(rho):
    rho_ev = eigvalsh(rho)
    return -sum(rho_ev * nan_to_num(log(rho_ev)))
#%%
# plot some eigenstates
def plot_eig(n):
    rho = zeros_like(rho_E) ; rho[n][n] = 1.
    assert entropy(rho) == 0.
    fig, ax = wigplot(wignerify(rho_x_from_E(rho_E_time(rho, 0))))
    fig.savefig(f'wigner_eigenstate/wigner_eigenstate_{n}.png')
    fig.close()
plot_eig(0)
plot_eig(5)
plot_eig(30)
plot_eig(40)
#%%
# plot the equilibrated distribution
rho_E_equilib = rho_E * eye(len(rho_E))
fig, ax = wigplot(wignerify(rho_x_from_E(rho_E_time(rho_E_equilib, 0))))
fig.savefig('wigner_equilibrated.png')
# plot the initial distribution
fig, ax = wigplot(wignerify(rho_x_from_E(rho_E_time(rho_E, 0))))
fig.savefig('wigner_initial.png')
print(f"Initial entropy = {entropy(rho_E)}")
print(f"Equilibrated entropy = {entropy(rho_E_equilib)}")
#%%
# plot the significant (99.9%) Schmidt-decomposed pure states at times 0,0.5,1
def schmidt(rho_E, label):
    rho_eigval, rho_eigvec = eigh(rho_E)
    cumprob = 0.
    for i,(prob, vec) in enumerate(zip(rho_eigval[-1], rho_eigvec.T[-1])):
        cumprob += prob
        vec_x = eigvec @ vec # pure wavefunction in x space
        rho_x = vec_x[:,None] @ conj(vec_x)[None,:]
        fig, ax = wigplot(wignerify(rho_x))
        fig.text(0.5, 0.90, f'schmidt[{i}] {label} prob={prob:.3f}', ha='center', va='top')
        # plot
        ax.plot(x,10*vec_x.real+2., color='lime', ls='solid', lw=0.3, ms=1., mew=0.2, marker='+')
        ax.plot(x,10*vec_x.imag+2., color='lime', ls='dashed', lw=0.3)
        fig.savefig(f'schmidt/schmidt[{i}] {label}.png')
        fig.close()
        if cumprob > 0.999:
            break
starting_point = 0 # sometimes the kernel dies.
# If it does, go to `wigframes` and check the last frame generated. Change this to that frame's index.
if starting_point == 0:
    schmidt(rho_E_time(rho_E,0.), label='t=0.0')
    schmidt(rho_E_time(rho_E,0.5), label='t=0.5')
    schmidt(rho_E_time(rho_E,1.), label='t=1.0')
# make a movie
framerate = 24
speed = 1.0 # how many time units per second
dt = speed / framerate
from tqdm import trange
progress_bar = trange(starting_point, 741)
for i in progress_bar:
    if i <= 500:
        text = None
        t = i * dt
    elif i <= 620:
        # jump forward to a late time
        text = 'one hour later'
        t = 3600*speed + i * dt
    elif i <= 740:
        # jump forward to a late time
        text = 'one year later'
        t = 365.2425*86400*speed + i * dt
    wigner = wignerify(rho_x_from_E(rho_E_time(rho_E, t)))
    progress_bar.set_description(f"range: {np.amin(wigner):.03f} to {np.amax(wigner):.03f}")
    
    sys.stdout.flush()
    fig, ax = wigplot(wigner)
    if text:
        fig.text(0.5, 0.90, text, ha='center', va='top')
    fig.savefig(f'wigframes/frame{i:04d}.png')
    fig.close()
    
# commands to make the video file:
# cmd='ffmpeg -framerate 24 -f image2pipe -i - -crf 20 -b:v 0 -an -c:v libvpx-vp9'
# cat wigframes/*.png | $cmd -pass 1 -f webm -y /dev/null
# cat wigframes/*.png | $cmd -pass 2 -y out-full-20-vp9.webm

pony in a strange land (talk) 22:31, 30 August 2024 (UTC)

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A barnstar for you!

	The Technical Barnstar
	Great diagrams on your Contributions page, both from technical quality and scientific depth! FDominec (talk) 10:00, 28 June 2024 (UTC)