User talk:Thermochap

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Again, welcome! Thermochap (talk) 14:36, 21 January 2008 (UTC)

Stereographic projection
Hi, Thermochap. Thanks for your recent edits to Stereographic projection. I like to see people working on the applications, since my edits are more focused on the math.

Minor point: You removed the fact that the real projective plane cannot be embedded in three-dimensional space R^3. I have restored it. The real projective plane can be immersed in R^3, and it can be embedded in R^4, but it cannot be embedded in R^3. This is a standard result in topology.

Welcome, and enjoy editing. Joshua R. Davis (talk) 22:43, 15 February 2008 (UTC)


 * Thanks for the heads up. I was less worried about its correctness in some context, than its clarity.  The real projective plane article says that it "cannot be embedded in our usual three-dimensional space without intersecting itself".  Hence it's a fact that a non-technical reader may find more confusing than enlightening, when the primary point of that paragraph was (I think) to say that visualization is not easy.  If you said "cannot be embedded"..."without intersecting itself", it would at least be consistent with that link page (for the moment).  I realize that a technical definition of "embeddable" might exclude self-intersection.  Nonetheless, it may not come across to many readers as the interesting fact that it is. Thermochap (talk) 23:03, 15 February 2008 (UTC)


 * "Embedding" does indeed exclude self-intersection, while "immersion" does not. The linked page's wording is colloquial. I think that the fact is relevant; it says that visualizing RP^2 is biologically impossible for humans (although tricks can let one almost do it). On the other hand, maybe it's a bit much. I'll think about it; let's move any more discussion to the talk page?


 * I hope you don't mind, but I've indented your response, per guidelines. Cheers-- Joshua R. Davis (talk) 23:53, 15 February 2008 (UTC)


 * Got it. Thanks!  Thermochap (talk) 00:08, 16 February 2008 (UTC)


 * P.S. Nice work on that revised wording as well. Thermochap (talk) 00:38, 16 February 2008 (UTC)

Point Defects
I appreciate your support on splitting articles for various crystallographic defects. As you might have noticed, it was me who suggested a split, but haven't been able to start a whole new article on its own. Although I'm still planning to start the article, I'd appreciate if you could initiate it and I'd join you in.

Also a little suggestion. Please don't mark your important edits as minor. This page might help you in choosing which edits to mark as minor. Thanks. LeaveSleaves (talk) 13:40, 7 March 2008 (UTC)


 * Oops. Thanks for the heads up on the use of m.  On point defects, I've had lots more first hand experience with all those other types of defects since you can examine them in detail by electron microscopy.  I also know something about the importance of point defects in the semiconductor industry, but will have to think about it for a while before I attempt something that's relevant to the larger picture.  I'll let you know if that happens.  Thermochap (talk) 13:48, 7 March 2008 (UTC)

Better Figure for Courtroom?

 * Thanks for the larger picture. I could dig up references for Turing/Good but it would take more time than I have available right now.  Good is famous for pushing the "weight of evidence" approach and wrote many papers and books based on it. — DAGwyn (talk) 15:19, 27 March 2008 (UTC)

Centrifugal force
I appreciate your efforts in this edit; it shows that you know what you're talking about, and the result was fairly nice. Unfortunately I had to revert it in order to fix David Tombe's undoing of the carefully crafted consensus version. In giving more-or-less equal weight to the fictitious and reactive notions of centrifugal force, the consensus version represents a compromise. Personally I would not give more weight to the "reactive" interpretation than your edit did, but there are editors who hold strong opinions otherwise, and unilaterally editing it out without gaining a good talk page consensus first would lead to nothing but strife and edit warring.

I assume that my reaction towards DT will seem a bit harsh to the uninitiated. Please know that he tried to edit the article about a year ago (before he created his current account), to reflect a rather, hm, unconventional take on how centrifugal force works. Most of the story is chronicled in Talk:Centrifugal force/Archive 4, and I'd advise you to skim through that before deciding how much effort to invest in arguing with DT.

I hope you'll stick around the article. The consensus version I reverted to can certainly use improvement. Just don't step too close to the "reactive" meaning with the pruning shears and it'll be fine. –Henning Makholm 08:58, 20 April 2008 (UTC)


 * Thanks, and keep up the good work. I was imagining a high school student being quite confused by what replaced that consensus version, and so figured I should do something in the short term.  Anytime there is a "consensus" version, it's probably better to storyboard improvements in talk before editing the main article.  I think details on use of the term for the reaction-force are nice, although it could probably use better references (not necessarily in the introduction).  An illustration or two may also help.  Thermochap (talk) 12:51, 20 April 2008 (UTC)


 * Below find a collapsable figure from the commons that might come in handy somewhere, as it shows clearly both of the forces discussed in that article. Thermochap (talk) 14:05, 20 April 2008 (UTC)


 * {| class="toccolours collapsible collapsed" width="60%" style="text-align:left"

!Worked example: Constant speed slingshot Forces on the stone include the inward centripetal (red) force seen in both frames, as well as the geometric (blue) force seen in the spin frame. Before the stone is released, the blue geometric force is purely centrifugal (pointing radially outward), while after release the geometric force is a sum of centrifugal and Coriolis components. Also seen in both frames is the force on the rope's anchor point (magenta) caused by Newton's 3rd Law action-reaction to the centripetal force on the stone.
 * [[Image:Cforces.gif|thumb|360px|center|Map and spin frame perspectives of forces associated with a stone released after being spun around on a massless rope.]]
 * [[Image:Cforces.gif|thumb|360px|center|Map and spin frame perspectives of forces associated with a stone released after being spun around on a massless rope.]]

Before projectile launch
The following alternate analyses of motion before the stone is released consider only forces acting in the radial direction. Both analyses predict that string tension T=mv2/r. For example if the radius of the sling is r=1 metre, the velocity of the stone in the map frame is v=25 metres per second, and the stone's mass m=0.2 kilogram, then the tension in the string will be 125 Newtons.

Map frame analysis before launch

 * $$-T_{centripetal}=\Sigma F_{radial} = m a_{radial} = - m \frac{v^2}{r}.$$

Here the stone is seen to be continually accelerated inward so as to follow a circular path of radius r. The inward radial acceleration of aradial=v2/r is caused by a single unbalanced centripetal force T.  The fact that the tension force is unbalanced means that, in this frame, the centrifugal (radially-outward) force on the stone is zero.

Spin frame analysis before launch

 * $$m \frac{v^2}{r} - T_{centripetal}=\Sigma F_{rot} = m a_{rot} = 0.$$

From the spin frame perspective the stone may be said to experience balanced inward centripetal (T) and outward centrifugal (mv2/r) forces, which result in no acceleration at all from the perspective of that frame. Unlike the centripetal force, the frame-dependent centrifugal force acts on every bit of the circling stone much as gravity acts on every ounce of you. Moreover the centrifugal force magnitude is proportional to the stone's mass so that, if allowed to cause acceleration, the acceleration would be mass-independent.

After projectile launch
After the stone is released, in the spin frame both centripetal and Coriolis forces act in a delocalized way on all parts of the stone with accelerations that are independent of the stone's mass. By comparison in the map frame, after release no forces are acting on the projectile at all.

The foregoing two properties: (i) ability to be eliminated by a suitable choice of frame, (ii) delocalized action on all elements of mass via accelerations that are independent of mass, are common to forces that arise from the connection term in a coordinate system's covariant derivative. Such geometric or improper forces include g-forces, Euler forces and gravity as well as Coriolis and centrifugal. They are in this way distinct from physical or proper forces that result e.g. from direct contact or electrostatic interaction.
 * }


 * Thermochap, the reason why I changed Henning Makholm's version (which he refers to as the consensus version) was because it argues that centrifugal force is a term which applies to two different forces.


 * This is quite untrue. And under his own admission, Henning Makholm states that this version is a compromise version designed to satisfy two conflicting viewpoints.


 * Science is not about comprise. If there is a controversy, then the fact of that controversy should be clearly stated in the introduction.


 * In the Henning Makholm version, an attempt is made to explain the centrifugal force that occurs inside a swerving car. There is only one centrifugal force acting. It causes the passenger to move towards the inside door. We cannot split this effect into a real effect and a fictitious effect. It is either real or fictitious.


 * The reason why I altered your version was because you stated that the centrifugal force is only viewed from the rotating frame of reference. That is not true. A centrifuge throws objects to the edge. This is an absolute fact which is independent of which frame we view it from.


 * Hence, I removed the bits that specified the rotating frame of reference.


 * Then at the bottom of your version, you said that centrifugal force used to be applied to some other reactive effect. If that is true, what is that other reactive effect referred to as nowadays?


 * It seemed like you were trying to sweep evidence of the fact that centrifugal force is real under the carpet.


 * Moving on now to my own version, I notice that you said to Henning Makholm that you had difficulty in imagining how high school pupils would react to my version.


 * How do you think that high school pupils would react to your paragraph that mentioned the affine connection?


 * The purpose of my version was to substantially simplify the article and state basically what centrifugal force is in its simplest terms.


 * I then stated that the official doctrine nowadays is that centrifugal force is a fictitious force, whereas in former times, it was viewed to be real.


 * I have given my reasons why I was not satisfied with either your version or the Henning Makholm version.


 * You have indicated that you believe that these matters should be discussed.


 * Can you therefore tell me exactly what it was about my version that you thought that high school students wouldn't grasp.


 * So far, my version has been removed by both yourself and Henning Makholm without as much as a single word spoken as to why.


 * PeR then intervened to try and claim that centrifugal force was never considered to be real and that should I try to prove otherwise by showing references, those references will be dismissed outright as constituting my own original research on the grounds that it will be deemed to be my own interpretation of those references. This reminds me very much of George Orwell's 1984 in which history gets systematically deleted.


 * We could take the same view regarding any reference.


 * At any rate, I have requested that a reference be provided to show that official teachings tell us that centrifugal force is a term which applies to two different forces.


 * If no such reference can be produced, the Henning Makholm version will have to be reverted.David Tombe (talk) 12:34, 21 April 2008 (UTC)


 * On the subject of references, you might want to cite the last sentence before the end of section on page 109 here as an example of use of the word centrifugal to apply to the reaction force which acts not on the rotation object, but on whatever holds that object in its circular path. This is an uncommon usage today, but one which is nice to mention in an encyclopedia article on the subject.


 * Better references to examples of the second type of definition on that page would probably also help, although these don't have to occur in the introduction. I suspect that most introphysics texts, as well as old texts that you have cited, use centrifugal to describe the force that a rotating object feels pushing it radially outward.  This is the more common usage today in physics, although I have no idea if that's also true e.g. in mechanical engineering.  Basically I think centrifugal can be applied to anything that points radially outward, just as centripetal can be applied to anything that points radially inward.


 * Much discomfort can be attributed to a poorly-informed choice of the word fictitious. This was perhaps first used in the vernacular (expressed literally) by teachers of Newtonian physics who didn't want their students to think about accelerated frames at all.  Folks now use it only in a technical sense, where it's not the opposite of real since "fictitious forces" pop up as useful tools in all kinds of accelerated frames.  In fact the equivalence principle and the tools of non-Cartesian geometry make it clear that connection forces, i.e. those not associated with proper accelerations, help one apply Newton's Law locally in any coordinate system.  Hence I prefer using the adjective "geometric" (rather than fictitious) for force terms that come from the connection.  Thus gravity and centrifugal are both geometric forces.


 * The goal of an introduction is to be friendly and clear, but not to explain or defend all points of view. That's what the subsections are for.  I think all see that there are two distinct forces the page has been discussing, and that only one of those forces arises from choice of an accelerated frame.  A shorter introduction to that page on centrifugal force, which reflects these things with cool links to supporting material might be nice.  I think that's most likely to evolve by adding inputs that augment insights others are bringing to the table. Thermochap (talk) 14:07, 21 April 2008 (UTC)

Thermochap, We've got to now work out a new introduction. I agree with you that it should be short and concise. That is what I was trying to do.

My first sentence stated the meaning of centrifugal force in its most basic form. It is an outward radial force which acts on an object that is constrained to move in circular motion.

Would you agree with that? The discussion of whether it is real or fictitious can be dealt with in the main article, although there should be a short note in the introduction to the extent that the modern view is that centrifugal force is fictitious, whereas in former times, it was believed to be real.

The reason that I altered your alteration of that sentence is because you added in more stuff about it being viewed from a rotating frame. That was superfluous to requirements because the entire effect is perfectly described simply by reference to the term 'radially outwards' in conjunction with 'circular motion'.

What do you think? David Tombe (talk) 02:51, 22 April 2008 (UTC)

WikiProject Microscopy proposal
You offered an opinion at WikiProject Microscopy proposal. Since that time, others (including myself) have offered their opinion. If you have the time, would you please review your opinion in view of the new information proposed. Thanks. GregManninLB (talk) 08:37, 26 May 2008 (UTC)

Nucleation
Never mind, I see my error now. I think I've made the page a little clearer. Miskimo (talk) 23:47, 8 December 2008 (UTC)

Icosahedral twins
I did a little format editing here, I am not competent to edit the substance of the article. Please remember that Wikipedia articles generally do not have "Introduction" sections, the "lead section" has no section header. Notes about the quality of the article or what it needs mostly go on the talk page, except for the standard cleanup tags, which are formatted in a way that makes it clear that they are not part of th4e article proper. I found this on new page patrol, by the way. DES (talk) 16:40, 28 October 2013 (UTC)

Proper Acceleration and rapidity
Hi,

Thanks, as I suspect you're the user who added the relationship between proper acceleration and $$\frac{\Delta \eta}{\Delta \tau}$$. Do you happen to have a reference to the derivation of this statement? It has come up in a project I'm working on involving projectiles in a uniform gravitational field. Thanks again for your contribution! Hcarter333 (talk) 15:04, 18 May 2014 (UTC)


 * One reference that I often cite is the first edition of Taylor & Wheeler's Spacetime Physics . Edwin indicated to me that the problem did not make it into later editions because teachers didn't quite know what to do with it. To that end, you'll find a bunch of suggestions about stuff that educators might do with proper-time, proper-velocity & proper-acceleration, in flat and curved spacetimes, up on this google sites page.


 * Free-float (like rain-frame) projectiles in a uniform gravitational field will I guess only experience a geometric-acceleration (affine-connection term), unless of course you try to hold them in a shell-frame (e.g. on the surface of a planet) with help from a proper-acceleration to clamp the shell-frame coordinate acceleration at zero. What's your application? Thermochap (talk) 12:33, 21 May 2014 (UTC)

Your submission at Articles for creation: Multiplicity (statistical mechanics) (February 24)
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Sulfurboy (talk) 04:11, 24 February 2020 (UTC)

Concern regarding Draft:Multiplicity (statistical mechanics)
Hello, Thermochap. This is a bot-delivered message letting you know that Draft:Multiplicity (statistical mechanics), a page you created, has not been edited in at least 5 months. Draft space is not an indefinite storage location for content that is not appropriate for article space.

If your submission is not edited soon, it could be nominated for deletion under CSD G13. If you would like to attempt to save it, you will need to improve it. You may request userfication of the content if it meets requirements.

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Thank you for your submission to Wikipedia. FireflyBot (talk) 13:05, 22 March 2021 (UTC)

Your draft article, Draft:Multiplicity (statistical mechanics)


Hello, Thermochap. It has been over six months since you last edited the Articles for Creation submission or Draft page you started, "Multiplicity".

In accordance with our policy that Wikipedia is not for the indefinite hosting of material deemed unsuitable for the encyclopedia mainspace, the draft has been deleted. If you plan on working on it further and you wish to retrieve it, you can request its undeletion. An administrator will, in most cases, restore the submission so you can continue to work on it.

Thanks for your submission to Wikipedia, and happy editing. Liz Read! Talk! 20:55, 10 June 2022 (UTC)

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