Talk:Wien's displacement law

message: Hi, 
The derivation currently featured is helpful, but I think some discussion of how x is "easily" found would be useful as well. lws (talk) 17:32, 27 October 2008 (UTC)
thread_title: Untitled

message: I have come across another way of expressing Wien's displacement law which is:
:{T\lambda_{max} = \frac{1}{5} c_2} where c2 is second radiation constant.
Both formulas are the same .  I'm no authority on the subject, but I would imagine Wien's displacement constant = 1/5c2.  It would be nice to see where Wien's displacement constant comes from and/or other other ways of expressing Wien's displacement law  —Preceding unsigned comment added by Devon Fyson (talk • contribs) 16:59, 29 January 2009 (UTC)
thread_title:  Alternate Formula 

message: The wavelength coincidence between the peak of the solar radiant power spectrum (at about 5800K) expressed in terms of unit wavelength interval, and the peak of the eye's spectral sensitivity function is just that - a coincidence or accident -- not something other as this article implies. If you express Planck's function in terms of unit frequency interval, you find the peak of that curve corresponds to a wavelength of about 880nm. If instead of power, you express Planck's function in terms of numbers of photons per second per unit wavelength interval (at 5800K), you find a wavelength peak at about 633nm. The problem is that Planck's function is a probability density function and thus doesn't transform simply with a change of units. The eye's spectral sensitivity function, however, is not a density function, so  changing units is straightforward. But it is misleading to attempt to compare the two types of functions. This is a common error in the vision literature and a common problem when interpreting density functions.
Moreover, all visual systems plainly reflect several constraints at least as important as the solar spectrum: they can't be too sensitive to the infrared without being subjected to noise created by the warmth of the eye itself; they can't be too sensitive to uv because of molecular instability; and they most likely reflect their phylogenetic origins in water, which itself filters the solar spectrum. 
All this is spelled out in "Some paradoxes,errors, and resolutions concerning the spectral optimization of human vision" Sofer and Lynch Amer. J. of Physics 67 (11) 1999
Apologies for all violations of protocol -- first time posting.
Greblams (talk) 08:15, 6 January 2008 (UTC)
replies: text: Actually, the primary factor would probably be that the system (like everything else about living things) is basically made of water. Ben Standeven (talk) 00:29, 12 January 2009 (UTC)
thread_title:  visual system and solar radiant power spectrum 

message: This page is mostly about what textbooks call Wien's displacement law, which is an observation about the Planck distribution, not what Wien actually discovered. The derivation should derive the real law, which tells you how to get the blackbody curve at any temperature from the blackbody curve at any other temperature. The relationship for the "peak" frequency comes out right, but it's not the fundamental thing.Likebox (talk) 14:11, 23 April 2009 (UTC)
thread_title:  Wien's Real Law 

message: Wien's constant "b", as I remember it, was exactly equal to k/h. It didn't have the ridiculous transcendental factor that appears in modern textbooks, as far as I remember, because Wein formulated his law in terms of the energy per mode, not in terms of the peak of the distribution. The constant b appears in Wien's work as the dimensional coefficient inside the function F,
::u/\nu = F(\nu/bT)
which immediately shows that b is just Boltzmann's constant divided by Planck's constant. The "b" in textbooks is a nonsense constant, it depends on whether you express the distribution in terms of frequency or in terms of wavenumber. The statement here that Wien did not consider his constant as a constant of nature is also suspect. What did he think it was then?Likebox (talk) 16:47, 23 April 2009 (UTC)
thread_title:  Wien's "b" 

message: In the "familiar approximate examples" section, under light from the sun and moon, the article states "Even nocturnal and twilight-hunting animals must sense light from the waning day and from the moon, which is reflected sunlight with this same wavelength distribution.". Is this actually true? Does this not require the moon be a perfect mirror? Obviously spectra from the moon will show some of that original shape, but accounting for the fact that the moon is a non-ideal blackbody itself, it seems fair to point out that light will be coloured. --144.32.126.12 (talk) 15:26, 27 April 2009 (UTC)
thread_title:  Reflection from the moon 

message: Now, it says "b = 28,977,685(51) nm·K." This is off by a factor of 10. I'd fix it, but don't know the proper formatting. 128.252.78.82 (talk) 14:55, 4 May 2009 (UTC)
thread_title:  Value for b incorrect 

message: Why does this article rot? The description of the law in the first paragraph decays to the textbook explanation with a time constant of about 1 month. If you don't know what Wein did, please don't edit the article.Likebox (talk) 15:51, 7 September 2009 (UTC)
thread_title:  Article Rot 

message: While I have no right to impose myself as an authority on how article leads should be written, I would like to appeal to some common sense. This is an encyclopedia, and should be written in a style that is accessible to anyone that has the prerequisite mental faculties using a vocabulary common to a wide interested audience.  Yet the article began referring to a "blackbody curve" with a link to an article about "black body" that does not contain the expression "blackbody curve". I just replaced that term with its definition. It further talks about "each mode" when it is anyone's guess what modes it is talking about. In fact, you have to know that we are talking about resonant radiation inside a cavity, and that such resonances have modes corresponding to the geometry of the cavity.  This makes the lead read as a paragraph from the middle of some quite long story.  
I think that it is perfectly admissible to have less accessible stuff later in the article, but the lead should be a little more inviting. I urge the editors to imagine the non-expert, intelligent reader when they write the lead.
The lead should be short and contain little more than a definition of the subject. It should allow the reader, who perhaps came to the page following a link while trying to make sense of another article lead, to return to the previous page with a rough understanding of what the keyword is about.  In this context it seems silly to me to explain how to divide by 10^9 (converting meters to nanometers) while taking for granted that the reader knows about the context of cavity approximations to black bodies.  Even the otherwise helpful explanation of the uncertainty digits in parentheses seems misplaced to me.  This should not be in the lead of an article about Wien's displacement law. 
Turn the reference to the CODATA source into a reference, to get it where it belongs, at the end of the article. (I shall see what I can do with that.)  —Preceding unsigned comment added by Cacadril (talk • contribs) 04:33, 9 March 2010 (UTC)
thread_title:  The lead has some issues of style 

message: According to the ångström article, "the use of the ångström is officially discouraged by the tohle je ončo vončo lvončo for Weights and Measures."  Anyone have any objection to sticking to SI units in this article?  --Vaughan Pratt (talk) 10:32, 16 May 2011 (UTC)
replies: text: I didn't know what Wien's Displacement Law was before reading this article (I was aware of the general relationship, but not the specifics). This article needs a good cleanup to be more reader friendly, and removing the darned angstroms from the article would be a good first step. Who uses angstroms anymore? Only those above the age of 40, that's who:P. If we're going to keep the angstroms in this article, maybe we should change all the temperatures from kelvin to Rankine, just for the old fogies who refuse to go SI. Gopher65talk 16:22, 6 October 2011 (UTC)
thread_title:  pičinks? 

message: Could we rename the section "Recommendation to de-emphasize" to Cristicism and possibly include other criticisms. 173.225.242.227 (talk) 08:54, 30 May 2023 (UTC)
replies: text: Sounds good to me.  I'll make the edit.  —Quantling (talk | contribs) 17:34, 17 July 2023 (UTC)
thread_title:  Suggestion