From: nospam@de-ster.demon.nl   
      
   Phillip Helbig (undress to reply)    
   wrote:   
      
   > In article <1p3imn8.10geog6da220gN%nospam@de-ster.demon.nl>, "J. J.   
   > Lodder"  writes:   
   >   
   > > Phillip Helbig (undress to reply)    
   > > wrote:   
   > >   
   > > > Not much effort is put into confirming or refuting undisputed results or   
   > > > expectations, but occasionally it does happen.  For example, according   
   > > > to theory muons are supposed to be essentially just like electrons but   
   > > > heavier, but there seems to be experimental evidence that that is not   
   > > > the case, presumably because someone decided to look for it.   
   > > >   
   > > > What about even more-basic stuff?  For example, over what range (say,   
   > > > multiple or fraction of the peak wavelength) has the Planck black-body   
   > > > radiation law been experimentally verified?   
   > >   
   > > Very well, given that the cosmic black body radiation has been measured   
   > > in great detail to better than a millikelvin.   
   >   
   > Yes, but at what frequencies?  As the name indicates, the CMB peaks in   
   > the microwave region.  It is well measured there, and a good way in   
   > either direction, but towards higher frequencies the intensity drops   
   > sharply.  Even ignoring confusion by other sources and so on, I doubt   
   > that it has been measured to any significant accuracy in the   
   > ultraviolet, not to mention the gamma-ray region.  (Photons here will be   
   > few and far between.)   
   >   
   > Yes, it looks like a perfect black body, no-one has convincingly argued   
   > that it should be otherwise, and so on, but the question remains over   
   > what range has that been verified.   
   >   
   > Discussing the CMB is a bit of a red herring, because if one saw   
   > departures from the black-body spectrum, one would suspect some   
   > astrophysical cause.  So think of lab measurements of black bodies: over   
   > what range in frequency have they been made and to what precision?   
      
   The fact that they can measure deviations of the CMB   
   from the ideal black body spectrum implies   
   that they can verifiy the black body spectrum   
   for a laboratory black black body to greater accuracy.   
   (they use one for calibration, iirc)   
      
   Asking about the high end tail is not very useful,   
   for there will always be a higher point   
   where it is not verified, so you can go on asking forever,   
      
   Jan   
      
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