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The Kirchhoff Function Quest


   At the April (February) 2010 APS Meeting, I focused on the underlying ideas in the historical development of the Black Body Distribution (Kirchhoff) Functions:

April 2010 APS Meeting               A Historical View of Kirchhoff’s Black Body Universal Distribution Function (Kλ)



(Abstract Correction: What was called the Rayleigh-Jeans attempt is really Rayleigh's original function. Jeans in his Conceptual Misunderstanding (See that section on the following website)
left out the exponential part and produced what is called the Ultraviolet (UV) Catastrophe).

 [COMMENT: The summary of this presentation in the History of Physics Spring 2010 Newsletter (see the last paragraph) was unfortunately inaccurate. This inaccuracy apparently occurred during the editorial process. It should have read:

In one of two concluding papers, Clarence A Gall presented a historical view of the development of the black-body radiation distribution (Kirchhoff) functions. He (Gall) then introduced a new function based on emission as a decay process that fits Stefan-Boltzmann's and Wien's (displacement) laws exactly. It (The new function) contradicts the traditional assumption that a hotter body always emits more intensely than a colder body for all light wavelengths which (the contradiction of the traditional assumption) is supported by observational infrared astronomy.
]

Wien's Distribution function was the first to satisfy both the Stefan-Boltzmann Law and Wien's Isothermal Displacement Law:


Click any image below for a more detailed view.

                      

Why was this law considered unsatisfactory? The answer lies in the traditional assumption that is never really expressly stated. However, the following statement by Rayleigh clearly explains this traditional reasoning:


                         

[Rayleigh's Remarks are available online at : 
<http://www.tandfonline.com/doi/abs/10.1080/14786440009463878>]

Rayleigh's Law expressed purpose was to satisfy the traditional assumption by assuring a continuously quasi-linear increase of intensity with temperature. Planck's solution did the same but had a lower slope:

       


The new Gall function based on emission as a decay process rejects the isochromatic part of the traditional assumption and leads not only to Wien's isothermal maximum but also to an isochromatic maximum which is supported by observational infrared astronomy.

     

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   Observational infrared astronomy has given an unanticipated support for Gall's new Kirchhoff function. However it would be interesting to test this isochromatic maximum prediction in laboratory Black Body Radiation measurements. This was the focus at the March 2010 APS Meeting:

March 2010 APS Meeting      Proposed Experimental Test of Gall's Predicted Isochromatic Black Body Displacement Law

In the historical view, the focus was on the 60 micron isochromatic curves in order to explain Rayleigh's remarks on Wien's Distribution (Kirchhoff) Law. That 60 micron wavelength is not considered convenient for laboratory studies of the isochromatic maximum prediction. Wavelengths in the 20 - 30 micron (500 - 333 cm-1range that lead to isochromatic maxima above laboratory room temperature but below 1000 K are considered ideal.



 
                      


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This experimental test is essential to clarify this fundamental problem that underlies science.


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