Talk:Stefan–Boltzmann law

message: "To find the total absolute power of energy radiated for an object..."
I am guessing that it should be "To find the total absolute power radiated by an object..."  —Preceding unsigned comment added by 82.32.49.157 (talk) 06:32, 4 May 2011 (UTC)
thread_title:  What dooes this mean ? 

message: It should be included or mentioned, because it's one of the two laws that describe the blackbody radiation. 91.153.156.165 (talk) 01:12, 12 December 2008 (UTC)
replies: text: I agree. I have mentioned it in my note below about why the Stefan Boltzmann law cannot be used to determine the temperature achieved by a combination of two or more sources of radiation. 202.172.115.20 (talk) 21:04, 16 November 2016 (UTC)
thread_title:  Wien's displacement law 

message: It would be nice to give a different derivation of the intergal J in the appendix than the one in the article Planck's law of black body radiation. I suggest to do a contour integration of the function \frac{\exp(i k z)}{\exp(z)-1} over the contour from zero to R and then to R + 2\pi i, 2\pi i+\epsilon, then a clockwise quarter circle with radius \epsilon and center 2\pi i to 2\pi i-i\epsilon and then back to zero. Count Iblis 13:30, 4 September 2006 (UTC)
thread_title: Old talk

message: This section should include that the energy radiated at the sun's surface, as can be calculated by the Stefan-Boltzmann law is 6.32899e+07 W/m2  —Preceding unsigned comment added by 71.111.6.64 (talk) 16:44, 4 April 2010 (UTC)
thread_title: Temperature of the sun

message: Any ideea why some sources give a different value for the constant?
e.g.:
"Stefan-Boltzmann Law
This is the relationship between luminosity (L), radius (R) and temperature (T): 
L = (7.125 x 10-7) R2 T4
Units: L - watts, R - meters, T - degrees Kelvin"
(See: http://science.howstuffworks.com/star3.htm)
or
"Stefan-Boltzmann Law - This is the relationship between luminosity (L), radius (R) and temperature (T):  L = (7.125 x 10-7) R2 T4.            Units: L - watts, R - meters, T - degrees Kelvin"
(http://www.nameastargift.com/astronomydictionary/index.html)
Units look ok. Why such a difference (maybe I am missing someting?) -Paul- (talk) 01:03, 9 February 2008 (UTC)
replies: text: The one in the article is smaller than those by a factor of exactly 4*pi, so it's probably the power per steradian instead of the total power.  In other words, someone got it wrong, I bet. Here's a book with an explanation that should help straighten it out. Dicklyon (talk) 06:23, 9 February 2008 (UTC)
thread_title:  Correct value of constant ? 

message: I've been doing some checkings how Stefan experimentally derived the law. Here it is just briefly mentioned that he deduced it on the basis of experimental measurements made by John Tyndall. Stefan in fact never knew for Tyndall's measurements directly, but he learned of them from Wülner's textbook on thermodynamics, where Wülner in his 2nd and 3rd editions had included Tyndall's data. He also arranged temperatures to Tyndall's colours of radiated light, which were a little bit arbitrary. As Tyndall he refered to Draper's measurements. Stefan read about Tyndall's data in Wülner's textbook and fortunately correctly changed two temperatures into absolute scale. The questions is - to which Draper do both, Tyndall and Wülner, refer? My source says that Henry Draper in 1847 tried to establish experimentally at which temperature warmed body starts to radiate. He didn't succeed but he found out that energy density is increasing rapidly (exponently) and not strait proportional to temperature. Stefan read about Draper's measurement from his article in 1878. I guess Henry Draper can't be the right person, since in 1847 he was 10 years old, and I assume that it was his father John Draper. Tyndall also refers to Draper all over simply as Dr. Draper, and John Draper was also a physician. --xJaM (talk) 01:31, 5 March 2008 (UTC)
replies: text: Yes, John Crepeau from the University of Idaho in his article Josef Stefan: His life and legacy in the thermal sciences cites John Draper's article from 1878 Scientific Memoirs: Being Experimental Contributions to a Knowledge of Radiant Energy, so this is the right source and John Draper the right person. --xJaM (talk) 17:49, 5 March 2008 (UTC)
thread_title:  Tyndall's measurements 

message: A graph plotting power vs. temperature would be helpful to visualize the implications of the law. -- Beland (talk) 00:39, 6 March 2008 (UTC)
thread_title: Diagram request

message: " Global warming is an increase in this equilibrium temperature due to human-caused additions to the quantity of greenhouse gases in the atmosphere." is not true. At the very minimm, the phenomenon described is AGW. How about "Anthropogenic Global warming is an increase in this equilibrium temperature which is widely accepted to be due to human-caused additions to the quantity of greenhouse gases in the atmosphere. These differentially affect the earth's albedo at different wavelengths, ceteris paribus raising the equilibrium temperature."
:AGW is most often referred to simply as global warming.  Adding the unfamiliar word anthropogenic there mostly distracts the reader from understanding what we're referring to.  It would be better to put it in parens if you feel a clarificatin is needed, but then you'll want it not at the beginning of a sentence.  Alternatively, just leave out human-causeed, perhaps? Dicklyon (talk) 15:20, 27 June 2008 (UTC)
replies: text: GW could be caused by natural or artificial causes. AWG is the human caused version. The debate is whether AWG is significant or not.  — Preceding unsigned comment added by 101.170.255.231 (talk) 13:42, 25 June 2012 (UTC)
thread_title: GW v AGW

message: I just wonder if this realy is a wide used name for the boltzman's constant.
I have never heard of it befor  —Preceding unsigned comment added by 213.153.113.18 (talk) 14:44, 15 September 2008 (UTC)
replies: text: Stefan's constant and Boltzmann's constant are two different constants entirely. CrispMuncher (talk) 20:22, 16 May 2009 (UTC)
thread_title: Stefan's constant

message: The graph is misleading.  It talks of total energy emitted rather than power per unit area.  I did a spot check of the figures and they seem about right - it is only the caption that is wrong. CrispMuncher (talk) 20:29, 16 May 2009 (UTC)
thread_title:  Issues with graph 

message: I think it should be I(\nu,T)d\nu=\frac{2h\nu^3}{c^2}\frac{1}{e^\frac{h\nu}{kT}-1}. In the article, is d\nu missing or there's something I don't know? ("Integration of intensity derivation" part)  —Preceding unsigned comment added by 79.114.188.53 (talk) 18:35, 13 June 2009 (UTC)
thread_title:  Planck's Law 

message: It would be nice to have a short explanation of how Stefan-Boltzmann relates to climate models.DaveCrane (talk) 14:30, 17 December 2009 (UTC)
replies: text: I agree this should be included, because people will ask it. I know that Earth isn't a black body because of albedo and the insulating layer of the atmosphere, and its insulation changes with composition, and the albedo changes with what is on the surface (plants, rock, water, ice, etc.). But I don't know nearly enough to write an accurate explanation. 2601:441:5000:ADF0:35DA:C87E:75C2:A251 (talk) 14:22, 26 July 2023 (UTC)
thread_title:  Climate Change 

message: Someone added
The black body radius is defined by Stefan–Boltzmann law. It is the radius of an object given its temperature and its total absolute power of Energy radiated:
: R = \sqrt{\frac{P}{\pi\varepsilon\sigma T^{4}}}.
# What is ε here? Emissivity? Then why is it called black body radius, not grey body radius?
# Is this the radius of a black body disk radiating the same amount of power with the same temperature as the object? If that is the case, then it should be  R = \sqrt{\frac{P}{2\pi\sigma T^{4}}} since every disk has two sides that both emit radiation.
# It is claimed that "the black body radius is a concept that is excessively encountered in astrophysical science". Give a reference.
--Netheril96 (talk) 17:07, 6 July 2011 (UTC)
thread_title:  "Black body radius" 

message: I removed this: "irradiance, energy flux density, radiant flux, or the emissive power)"
The page for radiant flux gives the units of W, rather than W/m^2 as it is here, and "energy flux density" is a cryptic term.  Especially since flux defines "energy flux" to mean what "energy flux density" means here, meaning they are using incompatible definitions for the word "flux".
I do not believe that the terms should be added back -- the intro should be clear and concise, and giving every synonym is confusing.  If they are added back (preferably not in the intro), we need to make sure that we are using terms consistently. Kjsharke (talk) 01:53, 26 September 2011 (UTC)
replies: text: Hi, u have given reason for removing the flux related terms, but why did u remove emissive power term?? I agree that need not be in intro, but is there any other reason too? Like any other inconsistency? Yashpalgoyal1304 (talk) 17:13, 28 March 2021 (UTC)
thread_title:  Radiant flux 

message: I am a little puzzled by this statement in the derivation, which appears to be vital to obtaining the result: 'Because the pressure is proportional to the internal energy density it depends only on the temperature and not on the volume.'  I know the pressure depends only on the temperature, but I'm not convinced that the reason given for this is correct.  For example, in an ideal gas, the pressure is also proportional to the internal energy density:  P = (3/2) (U/V), yet the pressure of an ideal gas certainly depends on the volume as well as the temperature.  I think the key difference is that in this case, the energy density does not depend on the volume, but only on the temperature, and maybe there should be some explanation of why this is the case?  Alternatively, I may have missed something simple in which case I would appreciate it if someone could point that out to me.  — Preceding unsigned comment added by Tobycrisford (talk • contribs) 12:45, 18 December 2011 (UTC)
thread_title:  A question about the derivation given 

message: Do we need an appendix that shows how to calculate the integral that appears in the derivation? This is standard maths stuff and tangential to the subject matter of the article. I propose to remove it.  --Lambiam 11:37, 28 July 2012 (UTC)
replies: text: We need it because it is related to the subject matter in the way most sources treat it. I.e. many books on this subject matter explain how to compute this integral, because the symbolic expression of sigma in terms of the other constants is notable, including its derivation. The derivation is not entirely "standard math stuff", that's e.g. not the judgment F. Reif had when he wrote his book on statistical mechanics. The issue is that if you ask a class of 30 second year physics students to integrate the Planck distribution, chances are that no one will be able to do so, not even those who have happened to take the math course on complex analysis. But this is the judgement that is made by the sources that are chosen by the profs at university. Count Iblis (talk) 15:32, 28 July 2012 (UTC)

text: I've the same opinion as Count Iblis's. In the case of Planck's law I add some sentences as an Appendix because the special value of Riemann's zeta function plays an important role to open the door to quantum theory. But we need the new article about the relation between zeta functions and some physical phenomena, for example Boltzmann's law, Planck's law, Casimir effect and quantum Hall effect. Are they related to physical phenomena via renormalization, analytic continuation and something another important ways? Enyokoyama (talk) 14:30, 29 July 2012 (UTC)
thread_title:  Do we need the Appendix? 

message: In all my years, I've always seen this referred to as Stefan's Law rather than the Stefan-Boltzmann Law.  A quick search of the literature will confirm this.  The constant $\sigma$ is referred to as the Stefan-Boltzmann constant.  Would the Wikipedia administrators mind updating this site?  An example reference would be {\it Thermal Physics} by Daniel V. Schroeder (2000).  — Preceding unsigned comment added by 192.80.95.242 (talk) 21:25, 9 May 2014 (UTC)
replies: text: My many years of experience tell me that different authors variously refer to it as either Stefan's Law or the Stefan-Boltzmann Law. I find this variation within my own library of physics texts. It's just an example of some saying 'to-may-to' and others saying 'to-mah-to'.  — Preceding unsigned comment added by 24.223.130.32 (talk) 23:10, 21 May 2017 (UTC)
thread_title:  Name: Stefan's Law not Stefan-Boltzmann Law 

message: I am moving here a contribution made to the main article which seems to belong to this talk page instead. — Edgar.bonet (talk) 21:26, 24 January 2017 (UTC)
replies: text: The figure of 396W/m^2 would, if it came from a sun several times stronger than ours, raise a small black object orbiting the Sun (such as a metal marble) to about 288K because it would be uniform flux and the object would have high conductivity. But, because of T^4 in Stefan-Boltzmann calculations and because the flux to any location on Earth's surface varies, it would only achieve a somewhat lower global mean temperature. But our Sun is not that sun. Climatology energy diagrams clearly indicate that they get to about 396 by adding to solar radiation about twice as much back radiation and deducting non-radiative surface cooling. This is a totally incorrect application of the Stefan-Boltzmann Law. The back radiation, no matter its value (which they calculated to get the right answer) would never make the surface hotter than the region in the troposphere from whence it originated. No experiment anywhere confirms such a use of that law. Their diagrams show more energy coming out of the base of the atmosphere than enters at the top. What really happens is a totally different paradigm as explained in my 2013 paper "Planetary Core and Surface Temperatures" that is based on correct physics and which nobody has ever correctly refuted. You only have to think of Venus to realize how wrong is climatology science. If that doesn't convince you then find another explanation than mine as to what energy keeps the base of the Uranus troposphere hotter than Earth's surface even though it is on average more than 19 times the distance from the Sun than we are.  Douglas Cotton, Centre for the Refutation of False Science. 2001:8003:2683:D300:C060:91A5:26AE:42E (talk) 11:18, 12 October 2023 (UTC)
thread_title:  Effective temperature of the Earth 

message: === Confusion in symbol ===
The symbol used for radiant emittance in this page (Stefan–Boltzmann_law) is j^{\star} ,
while on other pages, it is M_\mathrm{e}. This was soo confusing. Yashpalgoyal1304 (talk) 17:42, 28 March 2021 (UTC)
thread_title:  Radiant emittance: Confusion & scope of expansion 

message: The symbol used for radiant emittance in this page (Stefan–Boltzmann_law) is j^{\star} ,
while on other pages, it is M_\mathrm{e}. This was soo confusing. Yashpalgoyal1304 (talk) 17:42, 28 March 2021 (UTC)
thread_title:  Confusion in symbol 

message: update: I've moved/copied this suggestion over to Radiant_exitance talk page.
Is radiant emittance same as emissive power? If yes, then can it be mentioned somewhere in this page?
Ref: Emissivity#Emittance
In #Radiant_flux Kjsharke mentioned the removal of emissive power term, but did not give any reason for it. Yashpalgoyal1304 (talk) 17:42, 28 March 2021 (UTC)
thread_title:  Scope of expansion