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This is an old revision of this page, as edited by Ucbear (talk | contribs) at 07:34, 9 January 2011 (→Wording and sourcing). The present address (URL) is a permanent link to this revision, which may differ significantly from the current revision.

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ordinal number, ordinal arithmetic, large countable ordinal, ordinal notation

Constructible universe, implicational propositional calculus, harmonic coordinate condition, Noether's theorem

User:JRSpriggs/Optimal monetary policy, User:JRSpriggs/Ordinal notation, User:JRSpriggs/Force in general relativity, User:JRSpriggs/Dirac particle in general relativity, User:JRSpriggs/Ani-Monday, User_talk:JRSpriggs/V

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Maxwell's equations in curved spacetime, Electromagnetic stress-energy tensor

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Theorem

I was willing to live with the content of formal theorem relegated to the very bottom of the article below "lore" and other junk. The group has had a year to consider its own ways to integrate the content in a merge. So I think the others should drop the rigid approach and include it as it was in your last edit to the article. Perhaps you could act in the capacity of voice of reason. My presence only brings into sharp relief the collective attitude. Be well, Greg Bard (talk) 00:55, 15 October 2010 (UTC)[reply]

Symmetry of stress-energy tensor

Hi. I noticed that you removed the "dubious" tag placed next to the assertion that the stress-energy tensor is necessarily symmetric and kindly added a citation. I agree that in general relativity, which is what MTW are discussing, the stress-energy tensor is indeed symmetric. The issue, however, is whether it is necessarily symmetric irrespective of the underlying theory. The "dubious" tag was placed there because the assertion is in direct conflict with the spin tensor article: "the stress-energy tensor isn't symmetric." The idea is that when the torsion tensor is nonzero, then the stress-energy tensor may not be perfectly symmetric. Zero torsion is an axiom of general relativity that may be relaxed. See Einstein–Cartan theory#Derivation of field equations of Einstein–Cartan theory for an example of a theory where this distinction is important. Teply (talk) 23:06, 29 October 2010 (UTC)[reply]

The whole idea of torsion is pure speculation, fringe science, since there is no empirical support for it. In addition to the argument given by MTW, symmetry is required for conservation of angular momentum.
Furthermore, if stress-energy is defined as (a constant times) the derivative of the matter Lagrangian with respect to the symmetric metric tensor, then it must be symmetric. JRSpriggs (talk) 06:12, 30 October 2010 (UTC)[reply]
By the way, if you want me to actually read something about Einstein–Cartan theory, then it should be written in the classical tensor notation of physicists using coordinate systems and tensor indices. I do not care to waste my time trying to read stuff written using "coordinate-free" notations or differential forms or frame-fields as these merely obscure what is really going on. JRSpriggs (talk) 07:08, 30 October 2010 (UTC)[reply]
I don't understand torsion so well myself, and I, too, am a fan of coordinates and tensor indices. And yes, the Einstein-Cartan theory article is in bad shape. I merely mentioned it in case you were one of the math-happy folk who like torsion. At any rate, I wouldn't call it "fringe science." When I just did a quick Google search for "general relativity torsion," one of the first hits is a Rev. Mod. Phys. article General relativity with spin and torsion: Foundations and prospects with 792 citations. I don't know much about this subject, but it strikes me as no wackier of addition to general relativity than, say, the cosmological constant.
Try not thinking of it in terms of torsion. Instead, try thinking about it in terms of spin. The stress-energy tensor article has for angular momentum conservation. This corresponds to the familiar nonrelativistic definition for angular momentum, . The trouble here is that this definition includes only orbital angular momentum. The metric tensor won't describe a spin 1/2 particle for you, so the distinction between orbital and total angular momentum doesn't come up very often. Ultimately, however, we are most interested in demonstrating conservation of total, not orbital, angular momentum. If you want to include spin in GR, I think you normally have to dispose of your metric tensor and use the tetrad formalism instead. You perturb the action/Lagrangian with respect to the tetrads instead of the metric.
By the way, I don't know much of anything about it, but the theory of teleparallelism seems to be a gravitational theory based entirely on torsion. Teply (talk) 21:55, 30 October 2010 (UTC)[reply]
Yes, to include spin in GR - which is unavoidable really - you have to go to with tetrads. Certainly not fringe; tetrads make testable predictions. --Michael C. Price talk 22:05, 30 October 2010 (UTC)[reply]
The spin of a macroscopic object is covered by the same equation as orbital angular momentum, provided that one can break it down into classical particles. We need to add a new subsection in Stress-energy tensor#Stress-energy in special situations on the stress-energy of a spinor field considered as a non-quantum field. Quantum mechanical spin is a quantum mechanical phenomenon which may have to wait on the advent of a quantum gravity theory.
To Michael C. Price: To be mainstream science, it is not enough to be test-able, it must be test-ed successfully. Do you have any reference for experimental results supporting tetrads? JRSpriggs (talk) 14:27, 31 October 2010 (UTC)[reply]
Tetrads are more computationally powerful than metric tensors in the following sense: 1) any prediction that can be made using the metric tensor alone can also be made using tetrads, and 2) tetrads can make a variety of predictions that metric tensors alone cannot make. You might want to read through Robert Wald's General Relativity for a rather unimpeachable, mainstream reference. He derives all of the elements of the Ricci tensor for the Schwarzschild metric by manipulating tetrads instead of the metric tensor. He also works with spin later in the book.
I like to compare the conceptual transition from metric tensor to tetrads with the conceptual transition from the Klein–Gordon equation to the Dirac equation. Dirac derived the Dirac equation by taking, roughly, the "square root" of the Klein-Gordon equation. This gave him effectively four equations (one for each component of the spinor) that could support spin-1/2. Similarly, you can interpret each of the tetrads as a kind of "square root" of the metric. Note that the Dirac equation in curved spacetime uses tetrads whereas the Klein–Gordon equation does not require them. Teply (talk) 19:00, 31 October 2010 (UTC)[reply]

The power of a theory is not evidence for its truth. If tetrads do not really exist, then including them in our theory will just be misleading (give false or self-contradictory results). For analogy, having an absolute state of rest or luminiferous aether would give our theory more power, but would contradict the empirical evidence which led to the special theory of relativity. Tetrads are one possible way to give meaning to spinors, but there may be other ways. For example, it is conceivable that two or more spinors (types of elementary particles) could combine together to give an object (tensor or tensors) which has meaning in the presence of gravity, while the spinors separately only have meaning when gravity is negligible. In other words, gravity might break the symmetry which keeps the spinors distinct from each other. JRSpriggs (talk) 21:43, 31 October 2010 (UTC)[reply]

I can only repeat what I said: to include spin in GR you have to go to with tetrads, even before you get to quantum gravity. When I was taught GR in the early '80s tetrads were taught as part of the course. The analogy Teply makes with the Dirac equation is apposite. --Michael C. Price talk 21:50, 31 October 2010 (UTC)[reply]

Thanks

For pointing out the spelling error. I cut and pasted it without noticing.Phmoreno (talk) 14:28, 3 November 2010 (UTC)[reply]

Reply

I have posted a reply to your reversion concerning my proposed edit of the Equation of State (cosmology) article on this article's Discussion Page.

Kentgen1 (talk) 19:14, 4 November 2010 (UTC)[reply]

Frege

Thanks for your comment at talk:Gottlob Frege. Would you support restoring the comment by Frege scholar Michael Dummett? Tkuvho (talk) 05:50, 7 November 2010 (UTC)[reply]

Growth deflation definition

Where are you getting your definition of growth deflation from?

Increasing supply of goods: This by itself is not a cause of deflation. The supply & demand relationship would quickly correct this, as less would be supplied at lower prices. However, a breakthrough in production and distribution costs is permanent.

Goods, not services: In reading what actually happened (Wells 1890, Bell 1940 and others) growth deflation happened because of technological improvements that affected the price of goods, not services. Competitive pressures did drive margins to near zero during past depressions, but that was not the primary cause of the deflation because it would have required negative margins to have the kind of deflation that actually occurred. It was clearly the result of increased productivity that caused the deflation.

If you have any sources to counter this claim I'd like to read them.Phmoreno (talk) 16:39, 7 November 2010 (UTC)[reply]

Regarding growth deflation: By "increase in the supply" in "an increase in the supply of goods (including real estate as well as chattel) and services resulting in competitive price cuts", I meant an enduring increase, that is, a shift in the supply curve. I would be open to using your terminology, if we make it clear that the cost reduction is real rather than just nominal. So we could say "an enduring decrease in the real cost of goods and services resulting in competitive price cuts". OK? JRSpriggs (talk) 22:11, 7 November 2010 (UTC)[reply]
Essentially, the way I see this list of causes has to do with the equation M*V=P*T (money times velocity equals price-level times transactions). Deflation means P is going down. This may be associated with any of three causes: T increasing (growth deflation, which is what we are arguing about); V decreasing (cash hoarding); or M decreasing (bank credit deflation). JRSpriggs (talk) 22:21, 7 November 2010 (UTC)[reply]
Using the term "real costs" is confusing because that is a circular definition. Essentially that is defining deflation in terms of "deflation adjusted cost". We are talking about declining production cost in excess of the overall deflation. Now it just so happened that margins did decrease for many goods during the deflationary periods, at least during the actual depressions (hence the term). I have not seen a study regarding how long margins remained depressed and how widespread the problem was during the six decade deflation. Also, the deflation was not continuous, though there were almost no periods of inflation.Phmoreno (talk) 00:41, 9 November 2010 (UTC)[reply]
No. Since we are talking about the T part of the equation (which part does not have to do with money), nominal (monetary) costs should not be part of the definition. The real cost of producing a good is not circular. It is the opportunity cost, i.e. the use-value of the consumption which people had to forgo when the production process began in order to have the means to be able to produce the good. This is not the same as the use-value of the good itself which occurs at a later time. Another way to look at this is to say that we are talking about the efficiency (think of the gain of an amplifier) of the production process, i.e. the real rate of return on (non-financial non-governmental) investments. JRSpriggs (talk) 02:49, 9 November 2010 (UTC)[reply]
Milton Friedman correctly stated that "inflation is always and everywhere a monetary phenomenon." So is deflation. OhioWanderer (talk) 21:20, 7 December 2010 (UTC) Without money there are no deflation and no inflation.OhioWanderer (talk) 21:29, 7 December 2010 (UTC)[reply]
It is not only a matter of money. If there were no goods or services, no transactions, then there would also be no inflation or deflation. Prices are a result of balancing goods and services against money. So one of the causes of deflation is an increase in goods and services while holding money fixed. That is what growth deflation is. JRSpriggs (talk) 22:48, 7 December 2010 (UTC)[reply]

With respect, there is some misunderstanding here: Firstly, it is only a matter of money: Friedman got a Nobel Prize for that. "If there were no goods or services, no transactions, then there would also be no inflation or deflation" is not a valid argument: In valid response I could state: if there were no people there would be no inflation and deflation or if there were no universe there would be no inflation and deflation. Barter economies operate without money. Inflation and deflation are impossible in such economies. Prices are a not a result of balancing goods and services against money. Prices are the exchange rate between items whether goods or services in terms of money which is a medium of exchange of equal real value at the moment of exchange, a store of increasing or decreasing real value over time and unit of account of increasing or decreasing real value over time. Prices are a result of balancing goods and services against real value and expressing that relationship in terms of money. Deflation is simply going backwards along the inflation curve. There would be nothing wrong with deflation when the Historical Cost Accounting model, i.e. the stable measuring unit assumption (which assumes that the prices (real values) of constant real value non-monetary items never maintained, eg. equity (capital, retained earnings, capital reserves, etc), fixed salaries, fixed wages, fixed rentals, etc have always in the past, currently are and will always in the future be 100% stable forever and a day) are rejected and with it the HCA model, and financial capital maintenance in units of constant purchasing power as authorized in IFRS in the Framework, Par 104 (a) twenty one years ago is implemented and the nominal prices of ALL constant real value non-nometary items are decreased in line with deflation: see Bernanke, et al, "there are no real price increases during pure hyperinflation" (and he is right.) Likewise: there are no real price decreases during pure deflation with no stable measuring unit assumption (HCA) and instead financial capital maintenance in units of constant purchasing power. Variable real value non-monetary items´ prices are already decreased in the market taking deflation into account in a deflationary economy like Japan´s. This would result in economic stability: going backwards along the inflation curve. Consumers would not hold back consumption waiting for items to get cheaper because they would know that their salaries would decrease in lock-step with prices and deflation: result: economic stability: an economy operating in real values only. Equity would decrease in lock-step too: all constant items: i.e. financial capital maintenance in units of constant purchasing power during deflation as authorized in IFRS twenty one years ago.OhioWanderer (talk) 23:24, 7 December 2010 (UTC)[reply]

I am sorry, but what you are saying is nonsense. I am not interested in continuing this conversation with you. Please do not post any more messages on my talk page. JRSpriggs (talk) 00:49, 8 December 2010 (UTC)[reply]

Ultimate fate of the universe

Have u read the Scientific American article before u undid on hoax?Efficiency1101e (talk) 13:15, 14 November 2010 (UTC)[reply]

The two references which you added to Ultimate fate of the universe to support your contribution are wild speculation having no scientific foundation. Popularizations where a journalist says that someone somewhere has claimed that the world could end in some bizarre new way do not count as reliable sources.
And just look at what you added: (1) "Dark Energy reverses itself..." How? Why should a physical force which acts one way suddenly start acting another way? It cannot. (2) "Somehow ordinary matter whips itself up into a frenzy..." How? Again, there is no theoretical basis for such a thing and no empirical support for it either.
Both of these are essentially saying that the world can act arbitrarily, when all of science shows us that the world does not act arbitrarily. JRSpriggs (talk) 13:47, 14 November 2010 (UTC)[reply]

Korean War is over

I see that you have reverted the Bombardment of Yeonpyong from being part of Division of Korea to part of the Korean War. We have been discussing this issue on the talk page, but no-one has presented any evidence to show that the Korean War belligerents regard the conflict as ongoing. The North Koreans say the war is over. The US State Department says the war is over. The South Koreans have not said the war is continuing. If you have some new references, other than the oft-repeated soundbite that "the war isn't over because there was no peace treaty", please provide them on the talk page. Don't you think it is more appropriate that the page is part of the Division of Korea which covers all aspects of North-South enmity and conflict since the partition in 1945, rather than torturing history by denying that the Korean War ended in July 1953 and claiming that it has in fact continued for the last 60 years? regards Mztourist (talk) 05:14, 29 November 2010 (UTC)[reply]

No. I do not want to repeat what has already been discussed at great length on that talk page. JRSpriggs (talk) 09:53, 29 November 2010 (UTC)[reply]
Well unless you or others have more to add to that discussion, I assume you will agree that the Bombardment of Yeonpyeong is part of the Division of Korea and not the Korean War. regards Mztourist (talk) 02:09, 30 November 2010 (UTC)[reply]

Composite Number Factoring Theorem

I see you were involved in the discussion on this page's talk page about it's proposed deletion. It didn't seem to be filed correctly; so I've posted a proper AfD. The article's AfD page can be found here. Thanks. — Fly by Night (talk) 17:50, 30 November 2010 (UTC)[reply]

Thank you for letting me know about it. JRSpriggs (talk) 19:29, 30 November 2010 (UTC)[reply]

Monetary policy

About your recent edit to the Monetary policy article,[1] I just want to explain the mainstream economics viewpoint a bit. It's not that economists think that deflation is always bad. The problem with deflation is that it causes problems during recessions and the aftermaths of financial crisis. The problems deflation causes are i) it prevents the normal functioning of monetary policy, as it is impossible to target a rate of interest lower than 0% (liquidity trap), ii) it increases the real value of debt, thus increasing bankruptcies and dampening future investment, delaying economic recovery, and iii) it causes fixed prices to rise in real terms, again delaying the economic recovery. I've made an edit along these lines to the 'gold standard' section of the Monetary policy article, and also cleaned up a bit. I'll be happy to continue our previous discussion of the issue of deflation further if you wish. (I realise I was sometimes brusque in our discussions before, for which I again apologise.) I'm on break between semesters now, and have a bit of free time on my hands. LK (talk) 04:05, 20 December 2010 (UTC)[reply]

I think your statement of the facts is mostly correct as far as it goes. But I think that you are not considering all of the relevant facts. Thus I reach the opposite conclusion — sustainable deflation is good at all times, even more so during a recession.
(i) "Normal functioning of monetary policy" is command-and-control, not the free market. Thus it is not something to be desired. Instead of trying to steer the economy, a central bank should focus on maximizing the value of its reserves divided by the monetary base. See User:JRSpriggs/Optimal monetary policy.
(ii) I agree that most debt is a problem. But to avoid the creation of debt in the future, we must avoid enabling those who enter into debt unwisely, i.e. avoid creating a moral hazard. Thus debtors must be allowed to suffer the adverse consequences of their foolish choices. Rescuing them by causing inflation just perpetuates the problem while harming the economy in general.
(iii) Actually the deflation which would naturally occur during a recession (if allowed to do so) is just the appropriate readjustment downward of those prices which were unduly raised during the boom. Thus it brings the recession to an end sooner.
Finally, if deflation (rather than inflation) had been the policy during the preceding period (the boom), then the boom and consequent recession would not have occurred. Instead (slower) normal but healthy and sustainable growth would have occurred throughout. JRSpriggs (talk) 21:30, 20 December 2010 (UTC)[reply]
There are several good reasons why a low inflation rate is preferable to a low deflation rate, and I think I can even convince you given enough time. Unfortunately, I mis-spoke earlier about saying that I had some free time. I actually don't. Things have come up. I'll have to delay replying until after the new year. regards LK (talk) 09:42, 24 December 2010 (UTC)[reply]
By the way, now that the 2010 is almost over, I have to concede that my prediction that the GDP would drop below that of 2009 was wrong. JRSpriggs (talk) 12:49, 24 December 2010 (UTC)[reply]

Wording and sourcing

Hi JR, I noticed this edit and I fully agree. However, the source was primarily intended to support the sentence about the potential. It now supports two sentences, which under normal circumstances is of course no problem, and it's no big deal, but do you see perhaps a way to have proper wording in one sentence for both potential and Minkowski? Tricky :-) - DVdm (talk) 17:30, 4 January 2011 (UTC)[reply]

It seemed to me to be a run-on sentence, especially after I added a phrase to it, so I split it. If you want to move the reference to the first part or recombine them together, that is OK.
However, I am now thinking that even my new version does not go far enough in restricting the applicability of Special relativity. Specifically, gravitational time dilation is not predicted by either Newton's theory of gravity or SR. What we need to say is something like this: if either or (where g is the maximum absolute value of the Newtonian gravitational acceleration within the region of interest, D is the diameter of the region of interest, and T is the duration of the region of interest) is non-negligible then SR is not applicable.
The reference given talks about linearized gravity, saying that is needed. But it does not say (as far as I can see) that this is sufficient to make the linearized GR the same as Newton's gravity plus SR. JRSpriggs (talk) 12:47, 5 January 2011 (UTC)[reply]
Hm... well, focussing on the source and on what is actually said in the first two sentences, and noting that we're not really talking specifically about time here in the section, I have replaced it with "Special relativity in its Minkowski spacetime is accurate only when the absolute value of the gravitational potential is much less than c2 in the region of interest.". I guess this adequately reflects the source, and it does not go in too much detail. It's also one properly worded and sourced sentence now. Cheers - DVdm (talk) 14:09, 5 January 2011 (UTC)[reply]

User page

Hello. I happened upon your user page and thought Wikipedia likely wasn't the right place for much of that material. I'd like to ask you to review WP:UPNOT and to please consider removing material that is not related to editing of Wikipedia. Ucbear (talk) 07:34, 9 January 2011 (UTC)[reply]

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