User talk:Jheald/Archive 2

Directive harmonizing the term of protection ...

Hi, you nominated Directive harmonizing the term of protection of copyright and certain related rights for a history merge, to make place for a move. Is there consensus for that move? I'm inclined to simply delete the target page without a histmerge, as there seem to have been no substantial, non-trivial edits on that page. I'll recreate it as a clean redirect which you can override by a move if you need. Let me know if you need the history back after all. Fut.Perf. ☼ 18:44, 26 January 2007 (UTC)

"Boltzmann's equation"

Changed Boltzmann's equation to point to Boltzmann equation, not Boltzmann's entropy formula. Anything else would be madness. Jheald 17:45, 5 February 2007 (UTC)

Yes, this sounds reasonable. Also, would you mind commenting here: Template talk:Thermodynamics timeline context. Thanks: --Sadi Carnot 18:44, 5 February 2007 (UTC

Kullback–Leibler divergence

Hi! Please see my comments on the talk page.... Cheers... MisterSheik 14:03, 3 March 2007 (UTC) Hi! Please see my response on my talk page.... Cheers... --MisterSheik 16:12, 4 March 2007 (UTC)

By the way, I want to add that I think that we're moving in the right direction and that the information entropy article has become much more readable in the last few days... So, thanks for the helpful edits! :) MisterSheik 16:15, 4 March 2007 (UTC)

Reply to CFD comment

I was too busy to check replies to my comments on that category discussion. So, let me reply here for the record (the cfd discussion is closed).

You wrote:

" "Using thermodynamics you cannot calculate the entropy" ???? I take it you have never taken a course on statistical thermodynamics, or even a basic course on solid-state physics, or you would have to calculate at the very least the heat capacity of the Einstein model of a solid, and its enhancement the Debye model? Nor ever used it to calculate the elastic properties of polymers (see eg loop entropy)? Calculating entropy and related quantities from formulas like the Gibbs entropy and the von Neumann entropy is an absolutely everyday occurrence, fundamental for understanding phase transitions, and a whole host of physical properties. "

I teach statistical mechanics at university and do research on exactly solvable models in 2d using Yang Baxter equations, Bethe Ansatz etc. So, I know what I'm talking about. You should have realized that I use the word "thermodynamics" in a more restrictive sense that you do. Also, "thermodynamics" is actually a misnomer, it should be called "thermostatistics", as pointed out by F. Reif in his textbook.

I agree with the points you made here:

" "most people who know what it means will think of entropy as discussed in the physics articles". I wonder if that is actually true or not. There are a lot of people who work with information who constantly use Shannon entropy, and never have to think of thermodynamic entropy at all - people working in data compression, signal processing, electrical engineering, statistical modelling, machine learning... I wonder if there may not actually be more of them than of people working with thermodynamic entropy. There would certainly be little sense in making the entropy in data compression a sub-category of thermodynamic entropy. But there are enough people that think like you, that thermodynamic entropy is "the" entropy, that that is why I originally thought to call the category "entropy in thermodynamics", rather than "thermodynamic entropy". I'm still myself not 100% sure as to which of those two namings is better. But both are more accurate than the category the overarching name "entropy", and then only putting thermodynamics articles there. No: the split into two sub-categories makes sense, and so does coming up with the right identifying names for those categories. Jheald 21:18, 10 March 2007 (UTC)"

Count Iblis 14:43, 17 March 2007 (UTC)

Equipartition theorem better now?

Hi Jheald,

Thanks for your great suggestions on the equipartition theorem; I tried to revamp the article so as to give a more qualitative description in the lead. Does it seem OK to you now? Any suggestions for further improvement would be most welcome! :) Willow 16:36, 30 March 2007 (UTC)

Hey, if you have time, could you please look over Encyclopædia Britannica and make suggestions for improving it? It's a Featured Article candidate now. Thanks! :) Willow 22:54, 30 March 2007 (UTC)

Hi, equipartition theorem has been improved still further; would you have a chance to look it over and make suggestions? Thank you, Jheald! :) Willow 13:17, 17 April 2007 (UTC)

Hypercomplex

Hello - thanks for going over several articles relating to hypercomplex numbers and adding content. I've begun some follow-up editing, and worked for starters on the multicomplex number article. I have a question about the use of direct sum vs outer product: You're using both, but I'm not entirely clear what the advantage for using one over the other would be in this case, if any. Comment appreciated: Talk:Multicomplex number Thanks, Jens Koeplinger 12:22, 1 April 2007 (UTC)

Black hole electron

Hi Jheald. Much more has been added to "Talk:Black hole electron"; thru item 9 Quantum-gravitational effect. I would very much like to know if you see anything there that you would disagree with. Many years ago Dirac said we have one too many constants in the quantum equations. He expected that we could, at some future time, derive the Planck constant. I want to add information relating to a derivation of this constant. Please let me know what you think of this. [[DonJStevens 16:38, 4 April 2007 (UTC)]]

List of venture capital firms

Hello!

You defended this page about 9 months ago. Just you know, I've remarked this for deletion. Please do not hesitate to revert me if you still feel it is worth saving.

Regards, --Abu-Fool Danyal ibn Amir al-Makhiri 17:12, 5 April 2007 (UTC)

thank you for your recognition

Hello, have I accidentally touched a raw nerve because you are very committed to Scholarpedia project? In the math project discussion page you commented on my staggering lack of knowledge and called the observation that their 'exhaustive coverage of a few narrow fields' (in present tense in the original) is largely empty facile. I am sure that you can back up your mighty talk with excellent academic credentials, because otherwise you would appear like an obsequious youth. Still, I would appreciate it if you retract your personal insults, and keep to constructive critique. Perhaps, you can compute the fraction of the articles that have already been written, and the average time it has taken (I had actually had gone through quite a few more than I indicated, and also noticed a few other peculiar things, although it hardly seemed prudent to post an exhaustive list in order to make my point). Sincerely, Arcfrk 01:12, 17 April 2007 (UTC)

Thank you for changing the tone of your comments. I think we both agree that Scholarpedia is not (yet) fully operational, but holds promise for the future. If you care to take a look, you might also agree that their coverage of Differential Equations is not on par with (current or projected) coverage of Ergodic Theory or Dynamical systems. Best, Arcfrk 22:45, 18 April 2007 (UTC)

Equipartition

Hi Jheald,

Would you have a moment to look over equipartition theorem again? I think it's improved a lot over the past week. Thanks muchly! :) Willow 22:37, 18 April 2007 (UTC)

Mean information

Sorry, I did not observe the hint to "average information content" in the article information entropy. Nevertheless, I think the phrase "mean information" is less clumsy and in analogy to "mean fitness" used in biology. Therefore there is no need for any article about mean information, but a look up word refering to "average information content" in information entropy would perhaps be good, because I have made some references to mean information, which must otherwise be taken away.--Kjells 07:19, 19 April 2007 (UTC)

possible answer

At talk:Good-Turing frequency estimation, you wrote:

According to the article:

The first step in the calculation is to find an estimate of the total probability of unseen objects. This estimate is $p_{0}=N_{1}/N$

The next step is to find an estimate of probability for objects which were seen r times, this estimate is $p_{r}={\frac {(r+1)S(N_{r+1})}{NS(N_{r})}}$

Where do these estimates come from? What prior probabilities are being assumed? -- Jheald 10:13, 4 March 2007 (UTC)

You might find the answer at empirical Bayes method. Michael Hardy 23:18, 4 May 2007 (UTC)

Spinors

Hi jheald,

I don't quite understand how you are using ideals in the Clifford algebra to isolate the column vectors. (For one thing, the Clifford algebra — or the part that matters anyway — doesn't have any two-sided ideals.) Anyway, that doesn't seem to me to be the way the Clifford algebra approach is normally viewed (in such explicit terms): the representations "exist" because the Clifford algebra is isomorphic to a complete matrix algebra. (Usually by some sort of complicated algebraic trickery.) Once you have this isomorphism, then you can start to talk about spinors in Δ (or, in even dimensions, Δ₊ and Δ_-) which are the column vectors on which the matrices act (the matrices, at any rate, purported to exist by this isomorphism). So, using ideals to isolate the column vectors is unnecessary: we already have the column vectors (in Δ, etc). In fact, these column vectors form the irreducible representation (no further reductions can occur). I do feel that an explicit description of the spinors is necessary, since the whole apparatus of Clifford algebras, while extremely useful for determining everything there is to know about spinors, has always left me with an odd feeling of something undone: So... what's a spinor anyway? Call me a Platonist.

Anyway, I don't think you're going to have much luck getting at the spinors through any sort of construction using the Clifford algebra, unless you're willing to accept what I say at face value: that there is such-and-so isomorphism. Some time back, someone had pointed out that there is no "physical" way to isolate the space of spinors. Thus to pin down what a spinor actually is, one is forced to look outside any algebraic constructions happening on the Clifford algebra. The "Explicit construction" is precisely such a gadget. Moreover, the lack of physicality is clear in this construction: it depends on an initial choice of isotropic space.

So don't try to make the Clifford nonsense satisfying in a Platonistic sense. It isn't supposed to. It's a complete and absolute kludge, albeit a very useful one. Silly rabbit 01:43, 5 May 2007 (UTC)

Ok, I see what you're doing. That's interesting. It has to work, but I don't see a way to get to the isotropic subspaces. Do we know, for instance, that (vf)² = 0? (Here v ∈ V and f is your projection operator — acting on the right, somehow I missed that before.) Silly rabbit 02:03, 5 May 2007 (UTC)

Alright, so I think a much cleaner way to go the route you're attempting is to say something along the lines of "The space of spinors Δ can be identified with a maximal anticommutative graded subalgebra of the Clifford algebra." That's actually a nice way to look at it. Of course, in even dimensions this decomposes into the even and odd parts. By your leave, I'd like to restore the original Clifford algebras section, and bring this in to the lead paragraph of the Explicit construction section. Silly rabbit 11:53, 5 May 2007 (UTC)

Thank you for the very detailed response on my talk page. I think I more fully appreciate what you are trying to do, but somehow it still needs to be fleshed out a bit better. You mentioned one case where the idempotent has a geometrical significance: A Lorentz boost up the null cone. This sounds promising. Let's both think about it. Silly rabbit 23:26, 5 May 2007 (UTC)

I don't see how to generalize the 1+e₀ directly. This doesn't even seem to have the correct rank to generate the spinor space as a left ideal (it's imprimitive). Here's another approach.

Another way to get at the spinors without relying on a fixed matrix representation is to consider nilpotent elements. In the language of the Detailed construction section, we can consider the tensor products

${\begin{bmatrix}0&1\\0&0\end{bmatrix}}\otimes \dots \otimes {\begin{bmatrix}0&1\\0&0\end{bmatrix}}.$

Any of these factors can be replaced by a copy of ${\begin{bmatrix}0&0\\1&0\end{bmatrix}}$, producing another nilpotent matrix. The left ideals generated by each of these matrices are isomorphic to a space of spinors. This can be formalized without referring to the matrices by choosing a basis v_i, w_i of V ⊗ C subject to the anticommutation relations

v_iv_j = -v_jv_i

w_i w_j = -w_jw_i

v_iw_j = -w_jv_i (i≠ j)

v_iw_i + w_iv_i= 1

In terms of an orthonormal basis of V, we can write

$v_{j}={\frac {e_{j}+ie_{j+k}}{2}},w_{j}={\frac {e_{j}-ie_{j+k}}{2}}.$

We can then form k-fold products of these, such as v₁v₂w₃... in 2^k different ways. (Thinking of these as matrices, each choice of v and w in a factor is the same as a choice of ${\begin{bmatrix}0&0\\1&0\end{bmatrix}}$ or ${\begin{bmatrix}0&1\\0&0\end{bmatrix}}$, respectively, in the tensor product construction.)

Now consider, for instance, the products

$\omega =v_{1}v_{2}\dots v_{k}$

${\bar {\omega }}=w_{1}w_{2}\dots w_{k}$ (Complex conjugate if V is real Euclidean space)

Then the left-ideal Cl(V) ω is a spinor representation. Moreover, the idempotent ${\bar {\omega }}\omega$ gives the projection onto this representation.

This more-or-less gives an explicit connection between the isotropic spaces and the orthogonal idempotents approach to arriving at the spin reps.

Sorry if this looks like a mess, I'll try to give you a cleaner presentation later. Silly rabbit 17:29, 6 May 2007 (UTC)

I'm now replying in part to your recent reply on my talk. The two approaches (idempotents versus isotropic spaces) are indeed related by an $\omega {\bar {\omega }}$-type construction (as indicated in my confusing meanderings above). Here ω is a generator of the upper-most wedge product of an isotropic space W (actually W′ in the Explicit construction notation) with itself. The annihilator of this generator consists of products of the complement of the isotropic space. A few things remain to be done, however,

1. Somehow give a "physical" or geometrical interpretation of the various operators involved (as you have done in the case of the Lorentzian projections).
2. Find an easy way to show that $\omega {\bar {\omega }}$ is idempotent (up to an overall constant, at least).

Anyway, I'm glad you brought this up since the two ways are certainly related, and it's worth exploring the precise relationship. Silly rabbit 13:51, 7 May 2007 (UTC)

Mathematical Physics

Hey Jheald, I noticed that you commented on the Mathematical Physicsarticle, albeit over a year ago. As such I thought I would let you know that this article is nominated for the Math Collaboration of the week (I nominated it). Even if this article does not make the cut, it needs serious work and I am not qualified to do it as of yet. If you get the time please take a look at it; if not, I understand, and thanks for your time--Cronholm144 01:09, 10 May 2007 (UTC)

Mandelstamm

Hello, this is a message from an automated bot. A tag has been placed on Mandelstamm, by Shoeofdeath, another Wikipedia user, requesting that it be speedily deleted from Wikipedia. The tag claims that it should be speedily deleted because Mandelstamm fits the criteria for speedy deletion for the following reason:

Housekeeping - cleanup per WP:SU

To contest the tagging and request that administrators wait before possibly deleting Mandelstamm, please affix the template {{hangon}} to the page, and put a note on its talk page. This bot is only informing you of the nomination for speedy deletion, it did not nominate Mandelstamm itself. Feel free to leave a message on the bot operator's talk page if you have any questions about this or any problems with this bot. Thanks. --Android Mouse Bot 2 00:13, 25 May 2007 (UTC)

First of all, calm down. I am sorry for removing the warning, I have done this before and people have thanked me for it. Second, it is clear that you are unaware of the extent of the WP:SU project. Hundreds of redirects are being deleted daily (most created by SU), and sometimes ones that are not exactly bad such as Mandelstamm are deleted. If you would like to re-create that as a redirect, feel free, it would not be deleted again.

Surname pages do not generally include all spellings of a name. Also, such pages are meant to direct other people to articles on Wikipedia, not give extra information. The amount of redlinks to include has been discussed already, and generally they are deleted if they do not have extensive "what links here" connections.

Note that I did not nominate Mane-Katz for deletion, which I could have after you removed the prod. It is my personal opinion that such stubs detract from the quality of Wikipedia. Am I not allowed to have such an opinion?

Sweeping PRODs of articles despite potential, and/or content on other wikis, and/or source text from reliable sources (eg Jewish Encyclopaedia).

Sweeping prods? I have prodded about 10 articles, and you are in no position to tell me what has potential. That is my opinion. If you disagree, remove the prods. Again, calm down. shoeofdeath 17:15, 25 May 2007 (UTC)

Regarding edits to Vector (spatial)

Thank you for contributing to Wikipedia, Jheald! However, your edit here was reverted by an automated bot that attempts to remove spam from Wikipedia. If you were trying to insert a good link, please accept my creator's apologies, but note that the link you added, matching rule \bmembers\.aol\.com\/.+, is on my list of links to remove and probably shouldn't be included in Wikipedia. Please read Wikipedia's external links guidelines for more information, and consult my list of frequently-reverted sites. For more information about me, see my FAQ page. Thanks! Shadowbot 21:19, 25 May 2007 (UTC)

Vector: Agree

I agree with your assessment of my recent edit. But the article needs some structural work, and we need an organized overview of things, I think. It would be nice to make it more elementary. Silly rabbit 12:30, 26 May 2007 (UTC)

Moreover, as far as I could tell, the old "Definitions" section didn't say anything consistent. I didn't think it was pitched at an elementary level, since you basically already needed to know about vectors (and bases!) to understand it properly. I'm going to try to do away with the section entirely, but try to reorganize the article around these fundamental ideas: geometry (Euclidean space), algebra (Cartesian coordinates), affine properties (addition/scalar multiplication), metric properties (norm, dot product, {cross product in 3D}), and physics interpretations. The material is there, but it needs some top-level restructuring. Silly rabbit 12:50, 26 May 2007 (UTC)

Reply: It's completely standard to do vector addition and scalar multiplication before introducing the dot product and length. See Strang "Introduction to Linear Algebra", Apostol "Calculus". Furthermore, I'm sure we both agree that this is the proper way to do things from a mathematical point of view, since length is an extra structure imposed on the vectors. Also, if you want to talk about the dot product, then you more or less have to have the an idea of vector addition and scalar multiplication in place already: The dot product is bilinear. For length, you have the triangle inequality. The compromise I am aiming for is to make this article suitable for linking from other more sophisticated articles (many of which may not assume a metric), but to preserve the elementary treatment. Some sectioning for easier navigation doesn't hurt either.

Also, I don't entirely agree with your view

But against that, consider that we're introducing vectors in simplest terms as objects with a magnitude and a direction.

That's fine for an intuitive interpretation of vectors, but it's not entirely accurate. Even in physics, incompatible units may not allow for a definition of magnitude. I think the subtleties of working this into the text, as other authors have tried to do (incorrectly, at that!) will make it far less readable. Treating vectors as directed line segments is just as intuitive, and if the reader wants to imagine length before it is formally defined, then I'm sure they're going to do that anyway. Silly rabbit 15:31, 26 May 2007 (UTC)

canonical ensemble

The point of notionally coupling a large number of copies together is to get an easy model of a heat bath and a straightforward transition from the stats for a microcanonical ensemble. It may be 'grossly wrong' but it's the way (IIRC, and I did check last time I had to justify it) I was taught it at Part 2! Bob aka Linuxlad 12:38, 26 May 2007 (UTC)

Cube Microplex pagemove

Hi there; what convention are you following in moving Cube Microplex to Cube Microplex, Bristol? So far as I know, wikipedia policy is to only have extra ", placename" for districts of cities or states, and otherwise we use "pagename (disambiguation type)" for disambiguating article titles. Is there some policy I don't know about with respect to this? Your move doesn't appear to be the only one for bristol-related articles so I'd like to track down who else is doing this. Kellen^T 10:33, 2 June 2007 (UTC)

Re: Beatles discography

Not rely, maybe a case could be made for using the cover of one or two of the most noteworthy albums mentioned in the "Historical background" section along with the text there, but most of it is still just a list with names, track listing, release dates, chart possissions and such. There is no actual commentary on individual albums (aside from the "Historical background" section), and that's as it should be. Detailed commentary belong in the articles about the individual albums (where using the cover art is fine as far as I'm concerned), not in the discography list. --Sherool (talk) 16:57, 5 June 2007 (UTC)

Re: CSD I6

Evidently, from your comment in talk CSD, you don't agree with suspending I6.

But the locus for this discussion has been WT:FAIR#Way forward, and there does seem to be consensus that this suspension is the appropriate thing to do, while attempts are made to clean up the tag mountain in ways that will minimise collateral damage, and bruising inflicted on ordinary Wikipedians.

If you don't agree, please enter into the discussion at WT:FAIR#Way forward.

In the meantime, it would be appropriate to suspend I6, pending this discussion.

Will you back out your revert, and leave I6 suspended, at least for the time being? Jheald 11:17, 9 June 2007 (UTC)

If you want to alter the criteria for speedy deletion, you ought to propose any change at Wikipedia talk:Criteria for speedy deletion; many editors who are concerned with the business of deletion will have that page on their watchlists and expect to see proposals suggested there. If you really want to propose a change, I suggest you do one that is confined in operation to the images that BetacommandBot has been tagging. --bainer (talk) 11:23, 9 June 2007 (UTC)

I have to be away from the net for the rest of the weekend. I simply cannot be online any longer. Please, can you draft something that you think is appropriate? There are 30,000 images BCbot has tagged, most of which can be legitimised - given the time to do it. Starting now deleting them all blindly cannot be the way to go. See also the depth of controversy and discussion at WP:AN/FURG. This is not (yet) the time for starting a mass deletion. Jheald 11:52, 9 June 2007 (UTC)

I won't be drafting anything because I think I6 is working fine. These images have had plenty of time already to be "legitimised"; the requirement for rationales has been present since the first processes to deal with non-free media were developed, and I6 was introduced more than a year ago. It's not the end of the world if images are deleted before someone gets to preparing a rationale, since image undeletion has been available for a year now. --bainer (talk) 12:02, 9 June 2007 (UTC)

Just some time to avoid the pain and aggravation this is going to cause. For the Project's sake as a whole. Is that so much to ask? Jheald 12:04, 9 June 2007 (UTC)

Convincing me won't be any use; if you want the policy changed you need to build a consensus at Wikipedia talk:Criteria for speedy deletion. I'll carry on carrying it out until it changes, and if it does, I'll carry out what it says then. --bainer (talk) 12:14, 9 June 2007 (UTC)

Hamiltonian mechanics

Hi, I did a merge of Hamiltonian mechanics and Hamilton's equations, please let me know what you think, is it what you had in mind? Regards sbandrews (t) 11:03, 10 June 2007 (UTC)

Thanks

Hello Jheald. I just wanted to leave a note saying thanks for fixing the Mark Antony link on the I, Claudius page. I am usually pretty thorough about making sure that my link doesn't cause a redirect and when I saw your correction I realized that all of the other names were in the cast list, which is where I was linking them from, but because MA was already dead at the time the story begins he wasn't in that list I had forgotten to double check his link. So thanks again and happy editing. MarnetteD | Talk 13:46, 27 June 2007 (UTC)