There is one other important detail in the discussion of light vs. temperature – the coherence or semi-coherence of the radiation. This is a step above “intensity”.
If it is semi-coherent, the term “superradiance” is used. Even “invisible”
IR light can be extremely visible – blindingly visible, when it is coherent
or semi-coherent.
A CO2 laser is all the evidence you need of that. The IR photons of this
laser are completely invisible to the human eye - unless coherent where they
show up as red.
The CO2 laser is important because this wavelength is near or identical to
where NASA thinks SPP are most easily formed. Of course, that could be
because they are using a CO2 laser :-)
From: H Veeder
_Colour temperature_ refers to the *peak* emission of a
blackbody whose temperature produces a peak emission within the visible
spectrum.
e.g. The surface of the sun is about 6000C and the peek
emission is white light so it has color temperature of white.
_Incadescence_ is the *visible* light emitted by a black
body at a given temperature.
An iron at 800C glows red but the peak emission is in the
infrared .
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