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Tom Mazanec
2018-Aug-27, 05:06 PM
What shade of blue would an infinitely hot object have? Any way to post a swatch of it?

Swift
2018-Aug-27, 05:16 PM
https://wikimedia.org/api/rest_v1/media/math/render/svg/832a1ef2f8099d115ffa2a931ce6165d644addcf
Wien's displacement law (https://en.wikipedia.org/wiki/Black-body_radiation#Wien's_displacement_law) describes the relationship between peak wavelength of the black-body curve as a function of temperature (b is a constant).

This becomes meaningless at infinity. I would also think that infinite temperature is meaningless (let alone "infinite hot").

grant hutchison
2018-Aug-27, 05:26 PM
For a black body, the colours follow the Planckian locus in CIE colour space. The shape of the black body spectrum as it crosses the visual range gets closer and closer to an exponential curve as temperature increases, so it converges on a particular shade of blue, as shown here:
:23518

By my calculations it comes out close to RGB 149,178,255, which looks like this:
23520
(Given that the RGB value for 1,000,000K is identical to that for 10,000,000K, I'm pretty sure the increment to infinity is neglible.)

Grant Hutchison

Tom Mazanec
2018-Aug-27, 07:03 PM
Beautiful.
Perhaps we could call it "Supernova blue".

profloater
2018-Aug-27, 07:41 PM
You have to remember our idea of colour is from a three frequency cone system which combines to give us colour perception. Some animals have more and can see into the ultra violet which we can not. As the black body spectrum shifts toward the blue for us it also shifts to the ultra violet. If we were illuminated by a super high frequency hot source,(ignoring infinity for this) we would call that “white”

George
2018-Aug-27, 08:07 PM
For a black body, the colours follow the Planckian locus in CIE colour space. The shape of the black body spectrum as it crosses the visual range gets closer and closer to an exponential curve as temperature increases, so it converges on a particular shade of blue, as shown here:
:23518

By my calculations it comes out close to RGB 149,178,255, which looks like this:
23520
(Given that the RGB value for 1,000,000K is identical to that for 10,000,000K, I'm pretty sure the increment to infinity is neglible.)
Yes, nice. That is what I imagined the color to be for our Sun's core. Though the core is perhaps 50% hotter, it makes little difference, which is also the case at a trillion K....

23521

The attached is energy ratio. The photon flux density ratio (violet to red) would be about half these numbers due to the fact that a 400nm photons carries almost twice (1.8x) that of an 750nm photon. Blue wins.

[Of course, we are assuming a Planck distribution.]