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I have copies direct scans of direct photographs of the original journal article, generously supplied to me by the BNF. They show Prevost's name in bold capitals without the acute accent. The font of the article contains the acute accented small capital e as may be seen from the rest of the article. Perhaps Prevost did not know that his name should be spelt with an acute e, or perhaps the editor of the original journal thought he knew better or made a mistake. Yes, one sees Prevost's name spelt with an acute e in secondary sources. Perhaps they knew better than the original characters. Perhaps you have some reason to put in the acute? Chjoaygame ( talk) 23:58, 18 October 2009 (UTC)
Thank you for your reply. In the originally printed journal article, of which I have a copy of what is probably a digital photograph kindly supplied to me by the BNF, one can see that the editor of the day did not know that he should omit diacritic marks for uppercase letters, and he supplied them liberally in several uppercase fonts, including the one in which he printed Prevost's name. He did not, however, supply one in the spelling of Prevost's name. I had checked this carefully in the original article when I posted the entry, because the acute accent mark does appear in secondary sources. Chjoaygame ( talk) 11:05, 20 October 2009 (UTC)
Thank you for your reply. Thank you for this research which is valuable to lead me to more works of Prevost/Prévost on the physical side. It seems that modern French thinks the name should have the accent while the fellow himself, or at least his contemporaries, didn't? Chjoaygame ( talk) 21:27, 20 October 2009 (UTC)
The concept of radiative equilibrium is as outdated as caloric and for the same reasons. Caloric failed as a concept because it treated heat as a material substance not as energy. In the early 18thC it became clear that mechanical work could be converted into heat without limit, thus there was no quantity of material substance that could be identified in a body that comprised 'the heat' i.e. a substance that made a body warm. Likewise radiation is a manifestation of energy that can have a source that is e.g. chemical or work. In particular radiation is freely exchangeable with chemical energy, it is the energy that is conserved not the radiation, thus 'radiative equilibrium is a meaningless concept. -- Damorbel ( talk) 18:10, 26 September 2010 (UTC)
Two unsigned talk-page entries, as follows, were posted today. Chjoaygame ( talk) 00:04, 12 April 2013 (UTC)
These two unsigned talk-page entries seem to be intended to start a general discussion. Here is not a place for general discussion. Here is a place for discussion specifically about edits to the article page. The two entries seem to seek discussion about things that are not the direct concern of this article page, but are perhaps, at a stretch, related concepts. It would be wrong to continue to try to promote on this talk page a discussion of the apparently intended kind. Chjoaygame ( talk) 00:04, 12 April 2013 (UTC)
Radiation is not a conserved quantity, so this whole article is invalid. Radiation is similar to heat in this respect. Radiation is freely generated when charge is accelerated and correspondingly radiation is completely annihilated when absorbed i.e. when it accelerates charge.
This may be difficult to grasp but the non-conservation of radiation lies at the heart of all quantum theory.
It is quite normal to find texts supporting radiative equilibrium but, as with heat and caloric, the authors are mistaken at the most fundamental level. The defects of any citation puporting to explain radiative equilibrium should be treated with the same respect as those explaining perpetual motion! -- Damorbel ( talk) 11:55, 12 April 2013 (UTC)
Should be merged with this article. Prokaryotes ( talk) 21:39, 22 September 2013 (UTC)
Per your request moved mechanism back to bottom, improved lede. There are now 2 examples in the lede and a clear definition (the reference could be improved). Prokaryotes ( talk) 05:06, 23 September 2013 (UTC)
Editor Prokaryotes has made a [number of edits that radically change the direction of the article, so as to make it accord with his special interest in climate, taking the article from its original nature as a general physical article. I do not like this at all. I think a specialist article on climate is a more appropriate place for Editor Prokaryotes to push his special interests in climate. It is evident that Editor Prokaryotes is resolutely determined to push those special interests, regardless of disagreement on the talk page; he makes changes that superficially seem to take regard of the talk, but the changes amount more to circumventive camouflage than to reasonable response. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
Editor Prokaryotes has put in a new and very special, muddled, and I think faulty definition of radiative equilibrium, for the sake of close focus on his special interest. His new definition needs strong revision. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
The examples in the new lead are specialized and inappropriate. Chjoaygame ( talk) 07:11, 23 September 2013 (UTC)
I can see that Editor Prokaryotes is resolutely determined and unreasonably violent in his Wikipedia editorial way of pushing of his point of view, and deeply muddled in this mind over the logic of the various kinds of radiative equilibrium. He has practically destroyed the logic of the article as it stood before his invasion. He has created a nearly new and nearly incurably muddled article on a different topic. I do not have time or inclination to struggle against his kind of editing practices. Chjoaygame ( talk) 09:44, 23 September 2013 (UTC)
The section in the article on approximate radiative exchange equilibrium is to some degree inappropriate, and now that editor Prokaryotes has drawn my attention to it, I am removing it. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
Can we remove that page notification now? I reworked most of the article, removed repeats, weasel wording, errors and reconstructed the topic to better reflect the science. Prokaryotes ( talk) 07:59, 23 September 2013 (UTC)
This article has rapidly been changed, from a more or less systematic account of the various physical notions of radiative equilibrium, to an expression of some ideas of climate theory. Is this the way the article should go? Chjoaygame ( talk) 19:49, 23 September 2013 (UTC)
I am inclined to agree with you. This article is about the general topic. The stuff that Prokaryotes has added to the lede is garbled and mangled William M. Connolley ( talk) 21:26, 25 September 2013 (UTC)
I've changed the first sentence to more clearly define what radiative equilibrium is, with a reference to a recent book on the subject. -- Slashme ( talk) 22:21, 14 October 2013 (UTC)
How relevant is the term "pointwise"? Isn't pointwise equilibrium the same as just equilibrium?
Also i recently removed this part from the section "Pointwise radiative equilibrium is closely related to Prevost's absolute radiative equilibrium", because it was unsourced and i think it is enough to mention his studies in the history part (which is new). And he referred to fluids... The section could be improved further.
Prevost wrote:
RADIATION AND ABSORPTION. Absolute equilibrium of free heat is the state of this fluid in a portion of space which receives as much as it allows to escape it.
Page 6 http://archive.org/stream/lawsofradiationa00bracrich/lawsofradiationa00bracrich_djvu.txt Prokaryotes ( talk) 06:32, 25 September 2013 (UTC)
This article remains a wreck made by an editor who thought he could improve it, and rejected other views. I have not tried to fix the wreck, which is beyond piecemeal repair. Chjoaygame ( talk) 03:50, 6 August 2015 (UTC)
If the two ideas are kept separate then the page becomes much easier to understand. Alternatively since absolute radiative equilibrium is a balance without regard to anything else at all and is therefore more of a very simple arithemetical idea rather than a complex thermodynamic one, just describe what it is with respect to planetary equilibrium temperature and direct people to that page
Although the idea of 'planetary equilibrium temperature' sounds totally wrong from the point of view of thermodynamics the idea is a very long established one going back to Prevost himself. DavidMarsh2016 ( talk) 20:23, 28 January 2016 (UTC)DavidMarsh2016
I just reverted an IP edit that added a parenthetical comment that radiative equilibrium can also be called radiative balance. That's not true: wikt:radiative balance is how much more energy is coming in vs going out of a system by radiation. -- Slashme ( talk) 07:01, 17 February 2017 (UTC)
This page contradicts itself:
"Radiative equilibrium is the condition where the total thermal radiation leaving an object is equal to the total thermal radiation entering it."
- vs. -
"This means that, at every point of the region of space that is in (pointwise) radiative equilibrium, the total, for all frequencies of radiation, interconversion of energy between thermal radiation and energy content in matter is nil (zero)."
The first statement subscribes to the Prevost Theory of Exchanges (a Caloric Heat-based model first promulgated in 1791 which treated radiation as a rarefied material substance, and placed upon the midden heap of scientific knowledge by none other than James Clerk Maxwell, who convinced the scientific community to subscribe to the Kinetic Theory of Heat), which makes the claim that all objects above 0 K emit regardless of ambient energy density or the existence of other objects in line-of-sight of the emitting object.
In reality, 2LoT holds even on a per-interaction radiative exchange basis.
At thermodynamic equilibrium, the Helmholtz Free Energy is zero: F = U - TS Where: F = Helmholtz Free Energy U = internal energy T = absolute temperature S = final entropy TS = energy the object can receive from the environment
If U > TS, F > 0... energy must flow from object to environment. If U = TS, F = 0... no energy can flow to or from the object. If U < TS, F < 0... energy must flow from environment to object.
If U = TS, p_photon = u/3 = p_object, energy cannot flow because no work can be done. Photon chemical potential is zero.
Let's look at the Stefan-Boltzmann equation: q = ε σ (T_h^4 - T_c^4) A_h
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c1 P/A = ε σ T^4 = c/4 * Energy density Energy density = 4/c σ T^4
At 303.15 K, energy density is 0.6384870391162539e-5 J/m^3. At 287.64 K, energy density is 0.51751020211456733e-5 J/m^3.
It requires energy (an energy gradient) to perform work, to provide the impetus for any action... in the case above, it would require external energy performing work upon the system to force energy to flow against an energy gradient of 0.12097683700168657e-5 J/m^3.
The above is why the Prevost Theory of Exchanges is an outdated model of energy exchange.
71.135.41.65 ( talk) 23:24, 30 January 2021 (UTC)
Reference #5 is a dead link: Mihalas, D., Weibel-Mihalas, B. (1984). Foundations of Radiation Hydrodynamics, Oxford University Press, New York ISBN 0-19-503437-6.
Here's an updated link: https://www.sciencemadness.org/lanl1_a/lib-www/books/00418557.pdf 2606:1A40:1002:0:1978:639B:DE36:9075 ( talk) 21:02, 16 May 2022 (UTC)
![]() | This article is rated Start-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||
|
I have copies direct scans of direct photographs of the original journal article, generously supplied to me by the BNF. They show Prevost's name in bold capitals without the acute accent. The font of the article contains the acute accented small capital e as may be seen from the rest of the article. Perhaps Prevost did not know that his name should be spelt with an acute e, or perhaps the editor of the original journal thought he knew better or made a mistake. Yes, one sees Prevost's name spelt with an acute e in secondary sources. Perhaps they knew better than the original characters. Perhaps you have some reason to put in the acute? Chjoaygame ( talk) 23:58, 18 October 2009 (UTC)
Thank you for your reply. In the originally printed journal article, of which I have a copy of what is probably a digital photograph kindly supplied to me by the BNF, one can see that the editor of the day did not know that he should omit diacritic marks for uppercase letters, and he supplied them liberally in several uppercase fonts, including the one in which he printed Prevost's name. He did not, however, supply one in the spelling of Prevost's name. I had checked this carefully in the original article when I posted the entry, because the acute accent mark does appear in secondary sources. Chjoaygame ( talk) 11:05, 20 October 2009 (UTC)
Thank you for your reply. Thank you for this research which is valuable to lead me to more works of Prevost/Prévost on the physical side. It seems that modern French thinks the name should have the accent while the fellow himself, or at least his contemporaries, didn't? Chjoaygame ( talk) 21:27, 20 October 2009 (UTC)
The concept of radiative equilibrium is as outdated as caloric and for the same reasons. Caloric failed as a concept because it treated heat as a material substance not as energy. In the early 18thC it became clear that mechanical work could be converted into heat without limit, thus there was no quantity of material substance that could be identified in a body that comprised 'the heat' i.e. a substance that made a body warm. Likewise radiation is a manifestation of energy that can have a source that is e.g. chemical or work. In particular radiation is freely exchangeable with chemical energy, it is the energy that is conserved not the radiation, thus 'radiative equilibrium is a meaningless concept. -- Damorbel ( talk) 18:10, 26 September 2010 (UTC)
Two unsigned talk-page entries, as follows, were posted today. Chjoaygame ( talk) 00:04, 12 April 2013 (UTC)
These two unsigned talk-page entries seem to be intended to start a general discussion. Here is not a place for general discussion. Here is a place for discussion specifically about edits to the article page. The two entries seem to seek discussion about things that are not the direct concern of this article page, but are perhaps, at a stretch, related concepts. It would be wrong to continue to try to promote on this talk page a discussion of the apparently intended kind. Chjoaygame ( talk) 00:04, 12 April 2013 (UTC)
Radiation is not a conserved quantity, so this whole article is invalid. Radiation is similar to heat in this respect. Radiation is freely generated when charge is accelerated and correspondingly radiation is completely annihilated when absorbed i.e. when it accelerates charge.
This may be difficult to grasp but the non-conservation of radiation lies at the heart of all quantum theory.
It is quite normal to find texts supporting radiative equilibrium but, as with heat and caloric, the authors are mistaken at the most fundamental level. The defects of any citation puporting to explain radiative equilibrium should be treated with the same respect as those explaining perpetual motion! -- Damorbel ( talk) 11:55, 12 April 2013 (UTC)
Should be merged with this article. Prokaryotes ( talk) 21:39, 22 September 2013 (UTC)
Per your request moved mechanism back to bottom, improved lede. There are now 2 examples in the lede and a clear definition (the reference could be improved). Prokaryotes ( talk) 05:06, 23 September 2013 (UTC)
Editor Prokaryotes has made a [number of edits that radically change the direction of the article, so as to make it accord with his special interest in climate, taking the article from its original nature as a general physical article. I do not like this at all. I think a specialist article on climate is a more appropriate place for Editor Prokaryotes to push his special interests in climate. It is evident that Editor Prokaryotes is resolutely determined to push those special interests, regardless of disagreement on the talk page; he makes changes that superficially seem to take regard of the talk, but the changes amount more to circumventive camouflage than to reasonable response. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
Editor Prokaryotes has put in a new and very special, muddled, and I think faulty definition of radiative equilibrium, for the sake of close focus on his special interest. His new definition needs strong revision. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
The examples in the new lead are specialized and inappropriate. Chjoaygame ( talk) 07:11, 23 September 2013 (UTC)
I can see that Editor Prokaryotes is resolutely determined and unreasonably violent in his Wikipedia editorial way of pushing of his point of view, and deeply muddled in this mind over the logic of the various kinds of radiative equilibrium. He has practically destroyed the logic of the article as it stood before his invasion. He has created a nearly new and nearly incurably muddled article on a different topic. I do not have time or inclination to struggle against his kind of editing practices. Chjoaygame ( talk) 09:44, 23 September 2013 (UTC)
The section in the article on approximate radiative exchange equilibrium is to some degree inappropriate, and now that editor Prokaryotes has drawn my attention to it, I am removing it. Chjoaygame ( talk) 07:10, 23 September 2013 (UTC)
Can we remove that page notification now? I reworked most of the article, removed repeats, weasel wording, errors and reconstructed the topic to better reflect the science. Prokaryotes ( talk) 07:59, 23 September 2013 (UTC)
This article has rapidly been changed, from a more or less systematic account of the various physical notions of radiative equilibrium, to an expression of some ideas of climate theory. Is this the way the article should go? Chjoaygame ( talk) 19:49, 23 September 2013 (UTC)
I am inclined to agree with you. This article is about the general topic. The stuff that Prokaryotes has added to the lede is garbled and mangled William M. Connolley ( talk) 21:26, 25 September 2013 (UTC)
I've changed the first sentence to more clearly define what radiative equilibrium is, with a reference to a recent book on the subject. -- Slashme ( talk) 22:21, 14 October 2013 (UTC)
How relevant is the term "pointwise"? Isn't pointwise equilibrium the same as just equilibrium?
Also i recently removed this part from the section "Pointwise radiative equilibrium is closely related to Prevost's absolute radiative equilibrium", because it was unsourced and i think it is enough to mention his studies in the history part (which is new). And he referred to fluids... The section could be improved further.
Prevost wrote:
RADIATION AND ABSORPTION. Absolute equilibrium of free heat is the state of this fluid in a portion of space which receives as much as it allows to escape it.
Page 6 http://archive.org/stream/lawsofradiationa00bracrich/lawsofradiationa00bracrich_djvu.txt Prokaryotes ( talk) 06:32, 25 September 2013 (UTC)
This article remains a wreck made by an editor who thought he could improve it, and rejected other views. I have not tried to fix the wreck, which is beyond piecemeal repair. Chjoaygame ( talk) 03:50, 6 August 2015 (UTC)
If the two ideas are kept separate then the page becomes much easier to understand. Alternatively since absolute radiative equilibrium is a balance without regard to anything else at all and is therefore more of a very simple arithemetical idea rather than a complex thermodynamic one, just describe what it is with respect to planetary equilibrium temperature and direct people to that page
Although the idea of 'planetary equilibrium temperature' sounds totally wrong from the point of view of thermodynamics the idea is a very long established one going back to Prevost himself. DavidMarsh2016 ( talk) 20:23, 28 January 2016 (UTC)DavidMarsh2016
I just reverted an IP edit that added a parenthetical comment that radiative equilibrium can also be called radiative balance. That's not true: wikt:radiative balance is how much more energy is coming in vs going out of a system by radiation. -- Slashme ( talk) 07:01, 17 February 2017 (UTC)
This page contradicts itself:
"Radiative equilibrium is the condition where the total thermal radiation leaving an object is equal to the total thermal radiation entering it."
- vs. -
"This means that, at every point of the region of space that is in (pointwise) radiative equilibrium, the total, for all frequencies of radiation, interconversion of energy between thermal radiation and energy content in matter is nil (zero)."
The first statement subscribes to the Prevost Theory of Exchanges (a Caloric Heat-based model first promulgated in 1791 which treated radiation as a rarefied material substance, and placed upon the midden heap of scientific knowledge by none other than James Clerk Maxwell, who convinced the scientific community to subscribe to the Kinetic Theory of Heat), which makes the claim that all objects above 0 K emit regardless of ambient energy density or the existence of other objects in line-of-sight of the emitting object.
In reality, 2LoT holds even on a per-interaction radiative exchange basis.
At thermodynamic equilibrium, the Helmholtz Free Energy is zero: F = U - TS Where: F = Helmholtz Free Energy U = internal energy T = absolute temperature S = final entropy TS = energy the object can receive from the environment
If U > TS, F > 0... energy must flow from object to environment. If U = TS, F = 0... no energy can flow to or from the object. If U < TS, F < 0... energy must flow from environment to object.
If U = TS, p_photon = u/3 = p_object, energy cannot flow because no work can be done. Photon chemical potential is zero.
Let's look at the Stefan-Boltzmann equation: q = ε σ (T_h^4 - T_c^4) A_h
http://hyperphysics.phy-astr.gsu.edu/hbase/thermo/stefan.html#c1 P/A = ε σ T^4 = c/4 * Energy density Energy density = 4/c σ T^4
At 303.15 K, energy density is 0.6384870391162539e-5 J/m^3. At 287.64 K, energy density is 0.51751020211456733e-5 J/m^3.
It requires energy (an energy gradient) to perform work, to provide the impetus for any action... in the case above, it would require external energy performing work upon the system to force energy to flow against an energy gradient of 0.12097683700168657e-5 J/m^3.
The above is why the Prevost Theory of Exchanges is an outdated model of energy exchange.
71.135.41.65 ( talk) 23:24, 30 January 2021 (UTC)
Reference #5 is a dead link: Mihalas, D., Weibel-Mihalas, B. (1984). Foundations of Radiation Hydrodynamics, Oxford University Press, New York ISBN 0-19-503437-6.
Here's an updated link: https://www.sciencemadness.org/lanl1_a/lib-www/books/00418557.pdf 2606:1A40:1002:0:1978:639B:DE36:9075 ( talk) 21:02, 16 May 2022 (UTC)