Wikipedia talk:WikiProject Physics/Archive June 2015

Merge proposal of conduction band and valence band articles

As the title says. Placing the discussion at Talk:Valence band.--Officer781 (talk) 11:26, 25 May 2015 (UTC)

Closed as merge.--Officer781 (talk) 05:19, 2 June 2015 (UTC)

Field (physics)

Folks, the article Field (physics) is rated as important but of low quality. Can some attention be directed to improving it. I've listed some "loose ends" in Talk:Field (physics). Perhaps other editors can weigh in on this. Thanks, Isambard Kingdom (talk) 13:48, 8 June 2015 (UTC)

AfD to consider

Wikipedia:Articles for deletion/Self-creation cosmology.

jps (talk) 20:17, 9 June 2015 (UTC)

An L/T variant of dimensional analysis

Additional opinion would be welcome at Talk:Dimensional analysis § L/T-only dimensions about the appropriateness of including an L/T-only variant of dimensional analysis. I'm surprised that with so many watchers that no-one else has chimed in. —Quondum 05:15, 2 June 2015 (UTC)

The L/T topic should (perhaps) have its own page, linked from the DA article's "See also" references... Rjowsey (talk) 11:30, 2 June 2015 (UTC)

 Done I've moved that discussion re L/T dimensional analysis into a new article: Complex spacetime. I realise it's an ambitious topic, but it's high time someone took a good hard look at the subject, so I'm volunteering. Any assistance greatly appreciated (most especially from smart people with a sense of humour). :D Rjowsey (talk) 22:56, 10 June 2015 (UTC)

Status of new article Complex spacetime

An editor, User:Rjowsey, has created the article Complex spacetime, and has started linking to it from physics articles. The status of that article in WP should be determined in terms of WP:OR, WP:N, WP:FRNG, etc., as well was whether it is ready for being in mainspace rather than draft. —Quondum 13:59, 10 June 2015 (UTC)

A message-box kept appearing in the article header reminding me that the Complex spacetime article is an "orphan". I commented it out, then removed it (it was distracting), but it kept returning. Pesky little bot! So I followed its advice, and put a few "see also" links into articles which seemed pertinent to some of the article's content, which I note you've reverted. Grace Hopper said: "It's easier to ask forgiveness than it is to get permission", so please accept my humble apologies. Rjowsey (talk) 22:48, 10 June 2015 (UTC)

This article is still decidedly in "draft" status. Not yet ready for prime-time. Lots more to do. I'll get cracking... Rjowsey (talk) 22:48, 10 June 2015 (UTC)

The manifold we live in clearly has four real dimensions. It might be embedded in a complex space, but it is not itself complex. JRSpriggs (talk) 02:26, 11 June 2015 (UTC)

Thank you. You've put your finger right on the point of confusion. I too, held that same point of view, until I came to understand its limitations. Because history, and math, forced me to expand my thinking, and to learn how to complexify the spacetime of special relativity, and general. We live in a universe which has three real dimensions (of Euclidean space), that unfolds through time. Einstein added a fourth imaginary dimension to encapsulate time in special relativity, 1905. Minkowski showed that Maxwell's equations were invariant under Lorentz rotation in this 4D spacetime, not realising that Maxwell's space had incorporated 3 real plus 3 imaginary dimensions. Maxwell had insisted, repeatedly, that EM could not be understood (mathematically) using vectors, nor tensors, but only with quaternions, which encapsulated his 3 imaginary dimensions nicely. QM is so profoundly successful because it embraces complexity, but it doesn't play nice with GR. The Dirac equation needs 5 dimensions of space, plus one of time. The Planck units of energy, force, momentum and power require 5 spatial dimensions, 2 of which must be mathematically imaginary, since they're orthogonal to our 3 real dimensions of space. So, over many years, I've been deeply interested in exploring how special relativity plays out in a (3r+2i+t)-dimensional spacetime. I'm certainly not going to try convincing you that complex numbers make relativity infinitely simpler, nor that GR and QM are natural bedfellows in a C^5,1 complex manifold. But it's true. Not because of some "theory" — I'm just using a different, and simpler, mathematical framework. Underneath existing theories. It's easy math, that can be readily understood by bright high-school kids. Even by me! Rjowsey (talk) 03:18, 11 June 2015 (UTC)

Anyone know if the topic deserves an article? user:YohanN7 and myself have tried today to fix the article into WP shape. M∧Ŝc²ħεИ_τlk 23:23, 14 June 2015 (UTC)

Draft: "Clifford algebra notation" subsection for article "Velocity-addition formula"

Clifford algebra notation

I have withdrawn the draft now since it would probably not pass WP rules.Twy2008 (talk) 03:45, 16 June 2015 (UTC)

Responses

I have looked at the article Velocity-addition formula and also Spacetime algebra (STA) and I decided I could try to write something about velocity addition or Lorentz transformations in special relativity using the Clifford algebra, STA. The above section might fit into the Velocity-addition formula article if the responses are positive after some more editing. It is possible something is very wrong with what I have written. Also, my skill at editing articles is sadly not as good as many editors like, so sorry about that. Tell me how to write articles better... what wiki editing software is best? Twy2008 (talk) 22:12, 12 June 2015 (UTC)

It suffers from the same problem as your Quaternion rotation biradial. TLDR. While I'm in favor of having fairly detailed proof outlines, not all are very enthusiastic about it. This is just too detailed even for my taste (whether correct or not, I have no idea and don't have the time to try to find out).

How about just smacking up the final formula, defining the terminology, and providing a reference? YohanN7 (talk) 17:38, 13 June 2015 (UTC)

• My impression is that it is an attempt at a derivation rather than an article. What would be the purpose? For someone to cross-check their own workings? Derivations don't really belong here. My first impression is that it is just too involved to check (making it useless). And my second reaction is that composition of boosts is dealt with in a Clifford algebra very simply: a rotor/versor (geometric algebra terminology for a Lorentz transform expressed in the Clifford algebra) acts on any vector (including a 4-velocity) in a very simple way (the sandwich product), and composition of rotors is by multiplication. This shouldn't take more than a few lines, and would best belong as a very short subsection on Lorentz transforms in Spacetime algebra § Spacetime algebra description of relativistic physics. And my recommendation would be to give the velocity-addition formula a complete miss: it is not in general useful, since the concept is poorly defined and mathematically clumsy. —Quondum 19:24, 13 June 2015 (UTC)

Draft:Quantum thermodynamics

Please assist with reviewing this draft. Fiddle Faddle 21:40, 15 April 2015 (UTC)

More feedback needed, please, to help us decide if this Draft is ready to overturn the consensus reached at Wikipedia:Articles for deletion/Quantum thermodynamics. Arthur goes shopping (talk) 12:22, 6 May 2015 (UTC)

I am just starting to look at this matter. My first impression is that the questioned article grew like Topsy from the following:

"A theoretical study has shown that it is possible and practical to build a reciprocating engine that is composed of a single oscillating atom. This is an area for future research and could have applications in nanotechnology. <Can a car engine be built out of a single particle? Physorg, November 30, 2012 by Lisa Zyga. Accessed 01-12-12 >"

Perhaps someone who is familiar with this matter will kindly be willing to confirm or discomfirm this first impression?Chjoaygame (talk) 13:57, 6 May 2015 (UTC)

I'm not sure who or what Topsy is and the quote and source you give isn't in the article, at least at present. Hence it it difficult to confirm you first impression. We have an article on quantum heat engines--perhaps that is what you are thinking of. This article is more about foundations of quantum mechanics of open systems than nanotechnology applications. I will say that the AfD referenced above had a lot of controversy--the AfD was closed, but I wouldn't call it a broad consensus. I worked on the article during that AfD and from what I remember, this is a very different article in terms of content--there is no fringe content (AFAICT) for one thing. --Mark viking (talk) 19:25, 6 May 2015 (UTC)

Thank you for that helpful answer. Like you I don't know who was Topsy. I just know that she grew in an unaccountable way. (Well, now we are in the Google age, I have found out a little about Topsy; she is a character in Uncle Tom's Cabin! And she grew unaccountably!) I tried to trace the past history of the article and was led to my quote.

The article refers to Lieb & Yngvason (1999) as a source for a quantum statistical derivation of the second law. I think that a rather odd reference for that purpose. I just now tried to reproduce my initial hunt for an origin of the article. Sorry I failed. But I see the article has a reference to the tiny heat engine. That has the same author as the article. I wouldn't call it far-out fringe, but it is not a really systematic account of its topic.

I am not impressed with a feeling that the article clearly distinguishes between open-system theory and non-equilibrium theory. I feel that is in principle a serious flaw.

At present I see the article as perhaps better entitled 'Uncle Ronnie's Fireside Chats'. It is not far from a summary of <[2] Kosloff, Ronnie. "Quantum thermodynamics: A dynamical viewpoint." Entropy 15, no. 6 (2013): 2100-2128.>. It gives me the feeling that it is self-promotion, not notable as a Wikipedia topic.Chjoaygame (talk) 22:53, 6 May 2015 (UTC)

I agree COI is a concern and reasonable editors can have differing opinions on whether it has compromised the article. But the field of quantum thermodynamics is much bigger than just Kosloff. People have been trying to reconcile quantum reversibility and thermodynamic irreversibility for a long time and for some the ergodic hypothesis, one of the foundations of quantum statistical mechanics, is something to be avoided if possible--here is a Nature review from 1985 on the topic. There is a Springer book on quantum thermodynamics by Gemmer, et. al.. The search term "quantum thermodynamics" gets 1,580 hits on GScholar and 2,150 results on GBooks. I don't have a personal stake in the field, but the field seems notable to me. --Mark viking (talk) 23:56, 6 May 2015 (UTC)

It seems you have considered this matter. Your just above comment suggests that you think, after reading the article, that 'quantum thermodynamics' is about how thermodynamics can derive irreversibility from quantum mechanics. Well, surely there is the same problem for deriving irreversibility from classical mechanics? My impression is that this is not what 'quantum thermodynamics' is about. So I would infer that the article misled you, and that is point against it. On the other hand, perhaps 'quantum thermodynamics' is indeed about nano-physics, which you did not mention in your just above comment?

The article starts as follows.

Quantum Thermodynamics

Quantum thermodynamics is the study of the relations between two independent physical theories: thermodynamics and quantum mechanics. The two independent theories address the physical phenomena of light and matter. In 1905 Einstein argued that the requirement of consistency between thermodynamics and electromagnetism... leads to the conclusion that light is quantized obtaining the relation $E=h\nu$. This paper is the dawn of quantum theory. In a few decades quantum theory became established with an independent set of rules . Currently quantum thermodynamics addresses the emergence of thermodynamic laws from quantum mechanics. It differs from quantum statistical mechanics in the emphasis on dynamical processes out of equilibrium. In addition there is a quest for the theory to be relevant for a single individual quantum system.

A dynamical view of quantum thermodynamics

There is an intimate connection of quantum thermodynamics with the theory of open quantum systems . Quantum mechanics inserts dynamics into thermodynamics, giving a sound foundation to finite-time-thermodynamics.

References

Does that suggest the article is about nano-physics? I think not. It suggests that 'quantum thermodynamics' is about how thermodynamics can derive irreversibility from quantum mechanics. On the other hand, I find a 2014 book by Günter Mahler entitled Quantum Thermodynamic Processes. Energy and Information Flow at the Nanoscale, Taylor and Francis. Glancing at that book, I see it is also concerned with the problem of derivation of irreversibility.

Glancing now at the 2004 book you mention (though your link did not work for me), by Gemmer, Michel, and (again) Mahler, I see it as mainly concerned with the derivation of irreversibility from quantum statistical mechanics. At a glance, it seems, unsurprisingly, that a derivation can be found from weak interaction with the surroundings.

My feeling is that this is an attempt to create a new subject that will justify a new department. Mark viking commented that the article is well written. But I don't see it as well constructed as a Wikipedia article. Perhaps I could say it is discursive. That the field may be notable does not, I think, mean it must have an article of its own. I am not moved to overturn the consensus.Chjoaygame (talk) 09:30, 7 May 2015 (UTC)

The page on Quantum statistical mechanics does not capture the idea of quantum thermodynamics. The article by Rkosloff on quantum thermodynamics is much more suitable and extensive. It covers the main approaches to the field 1) Dynamical view of quantum thermodynamics. 2) Typicality as a source of emergence of thermodynamical phenomena. 3) Quantum thermodynamics and resource theory. The topic of quantum thermodynamics is very relevant and contemporary, you can have a look on the web site <http://blogs.exeter.ac.uk/qut/>. — Preceding unsigned comment added by Lmikmik (talk • contribs) 15:01, 27 May 2015 (UTC)

I recommend to that the article "quantum thermodynamics" will have it own page and will not be included or merged with "quantum statistical mechanics" My main argument is the following: To merge "Quantum thermodynamics" with "quantum statistical mechanics" is even worse than to merge classical thermodynamics with classical statistical mechanics.

Like in the classical case the two theories have some overlap in few concepts e.g. entropy and temperature. However, the difference between the two theory in the goals and methods is huge. If the classical difference is not clear to some of the people who suggesting merging "Quantum thermodynamics" with "quantum statistical mechanics” I ask that they will reconsider their recommendation to merge the two.

Moreover, it is not a coincidence that "quantum statistical mechanics” in Wiki exist for so long and contain only very basic concepts (no actual results there). The reason is that this terminology is not used by physicists. I think it is wrong to use wikipedia to perpetuate it.

As for COI, the author of the Wiki page "quantum thermodynamics” is well known in the field and it is natural that some of his own work appear there. However he left space (i.e complete section) to fields in QT that he himself is not studying (like resource theory). At least he never published anything on these other field. I guess since he not an expert on these other field he wrote little on them and left for other users to extend them.

to see what is going on in quantum thermodynamics nowadays I recommend reading this most updated review. Inside there are reference to more specific review in quantum review. Even though this review is more dedicated to bridge between quantum thermo and information theory I think it describes well the current state of research in QT:

http://arxiv.org/pdf/1505.07835v1.pdf

Since it is just a review I expect it will soon be published in a peer reviewed journal.

For many years the field has been dormant but about 3 years ago it started to grow very rapidly. Here are links to few conference:

http://ifisc.uib-csic.es/qtd2/ http://www.wqit-quantum.if.ufg.br/p/7080-welcome https://qut.ethz.ch/events/12-events-past/49-conference

I am a physicist and not all physicists that I talk to immediately understand what QT is all about. Some think that it is about using quantum mechanics to explain thermodynamics. This puzzles them since classical thermodynamics can already be understood from statistical mechanics.

The goal of QT is similar to classical thermodynamics. To understand thermal transformation of open system coupled to thermal reservoirs. This may be a single shot work extraction scenario or a heat machine (engine refrigerator) working in steady state. What makes it quantum and also what makes it different from statistical mechanics (classical or quantum) is that the system is very small (e.g. one particle) so that: 1. It does not equilibrate on it own when not coupled to the bath. Furthermore in general it has no equation of state (e.g. one particle) that connects thermodynamics quantities like S,E,T,V... 2. Since there is only one or few particles involved ensemble average and statistical mechanics tools that really on many particle averaging cannot be applied.

Goal of quantum thermodynamics (just examples not a complete list):

---

In the context of heat machines QT concerns question like: what happens if a quantum heat machine is measure during it’s operation? what are the differences in thermodynamics quantities between a classical engine and a quantum engine? Are the new thermodynamics effects that do not appear in classical thermodynamics. Can quantum entanglement and quantum discord can be used to manipulate in new ways thermodynamics quantities such as work, heat and entropy generation? Can quantum catalyst be used for improving heat engine? What transformation are forbidden by QT? Are there extension to the second law in the microscopic world?

and so on...

As you can see the goals are very different from that of statistical mechanics (quantum or not).

In light of all this I highly recommend that "quantum thermodynamics” will be an independent article. The present version will soon be modified by the active community in this field once it is published. — Preceding unsigned comment added by Tnd1111 (talk • contribs) 07:25, 15 June 2015 (UTC)

I am a physicist working in the nascent field of quantum thermodynamics. Apart from my technical work, I share responsibility for the outreach campaign of a very large EU-funded project (technically a COST-funded Action) on Quantum Thermodynamics. I would like to add my voice in questioning the judgement that has been handed down on the draft article on quantum thermodynamics. The current article takes a point of view that is very far removed from the work that is being done in the field by physicists around the world. There are hundreds of recent peer-reviewed journal articles that take the point of view of Rkosloff and not the alternative viewpoint that is present in the current article which, as is hinted in the very first line, discusses Quantum Statistical Mechanics, and not Quantum Thermodynamics as the term is understood in the field.

I have no vested interest in this article other than the desire to see our field becoming a more familiar matter amongst undergraduates and even the interested general public. In my considered opinion, and here I represent the 220 scientists who are part of this network, whereas the current Quantum Thermodynamics article does not any justice to the field, the draft by Rkosloff provides a much-needed and very good start for achieving that goal. I very much welcome a discussion on the merits of the article, but amongst physicists and scientists and in the technical literature, the relevance of the subject matter is never questioned.

In summary: (i) The current Quantum Thermodynamics article discusses Quantum Statistical Mechanics, which is not what is understood by Quantum Thermodynamics in the literature; (ii) there is no Wikipedia article which addresses what is understood by Quantum Thermodynamics; and (iii) the draft by Rkosloff addresses both these needs and introduces to Wikipedia part of the work of over 220 scientists in this field who form a Europe-wide network. Regards, AndreXuereb (talk) 16:13, 22 June 2015 (UTC)

Copyright Violation Detection - EranBot Project

A new copy-paste detection bot is now in general use on English Wikipedia. Come check it out at the EranBot reporting page. This bot utilizes the Turnitin software (ithenticate), unlike User:CorenSearchBot that relies on a web search API from Yahoo. It checks individual edits rather than just new articles. Please take 15 seconds to visit the EranBot reporting page and check a few of the flagged concerns. Comments welcome regarding potential improvements. These likely copyright violations can be searched by WikiProject categories. Use "control-f" to jump to your area of interest.--Lucas559 (talk) 22:36, 25 June 2015 (UTC)

Draft:Prism_Spectrometer in AfC

Hi WP:PHYS,

The AfC queue is really (read, completely) backlogged - I'd like to invite any of you to poke this as well as any other physics related draft in AfC. Cheers! Accents 06:04, 15 June 2015 (UTC)

Also Draft:Extended Interaction Oscillator, Draft:Gamma voltaic cells and Draft:Precession Electron Diffraction. Thank you, FoCuSandLeArN (talk) 14:18, 19 June 2015 (UTC)

If the project can set up a way to prominently display

perhaps in the "to-do" list, these drafts might get more expert reviews sooner rather than later. Roger (Dodger67) (talk) 16:44, 22 June 2015 (UTC)

There would also need to be a to-do list to tag drafts with the WPPHYSICS banner in the first place for it to appear in that category. (For instance, Draft talk:Extended Interaction Oscillator does not contain a WPPHYSICS banner) ; (Perhaps by looking through the WPCOSMOLOGY and WPASTRONOMY drafts to see which are also physics topics) -- 70.51.203.69 (talk) 04:58, 25 June 2015 (UTC)

AFC is in the process of instituting a workflow update that includes adding project banners to all drafts, so expect the tagging rate to increase soon. Of course anyone is welcome to add project banners to drafts. Roger (Dodger67) (talk) 21:09, 26 June 2015 (UTC)

So, are we agreed, that WPPHYSICS should tag draft articles? (If so I'll spend a few minutes going through drafts and adding banners) -- 70.51.203.69 (talk) 05:13, 27 June 2015 (UTC)