The "Physicist" seems to muddle energy with temperature. If you follow his theory a matt black surface left in sunshine would end up the same temperature as a white one - which I'm pretty sure (if only personal empirical data) isn't the case, at all.

   - Andy.

no but in a vacuum it certainly would.
The reason that the black bits of the cat get hotter in front of the fireplace than the white is that the absorption rate is lower for the white,  Now the emissivity is also lower, but in air the loss from radiation, even from 'radiators' is not the main cooling mechanism. Given a more or less identical cooling, but a variable rate of heat absorption vs reflection now the white bits are cooler.

If you force the only available heating and cooling mechanisms to be radiative, then a uniform black object and a uniform white one reach the same final temp, just the black one gets there a lot faster. But for satellites if we make things that are white, or shiny,  on the side facing the sun and metallically connected to things that are darker - i.e good radiators and absorbers, on the side facing away from the sun, now the equilibrium is not the same as if it was turned about.

The thing is we thrive only because of the fact that the surface of the earth is not all at one uniform temperature, much as a uniform land level would be no good to us either as it would all be flooded, just not as deeply as the deep bits are now.

Mike.

no but in a vacuum it certainly would.
The reason that the black bits of the cat get hotter in front of the fireplace than the white is that the absorption rate is lower for the white,  Now the emissivity is also lower, but in air the loss from radiation, even from 'radiators' is not the main cooling mechanism. Given a more or less identical cooling, but a variable rate of heat absorption vs reflection now the white bits are cooler.

If you force the only available heating and cooling mechanisms to be radiative, then a uniform black object and a uniform white one reach the same final temp, just the black one gets there a lot faster. But for satellites if we make things that are white, or shiny,  on the side facing the sun and metallically connected to things that are darker - i.e good radiators and absorbers, on the side facing away from the sun, now the equilibrium is not the same as if it was turned about.

The thing is we thrive only because of the fact that the surface of the earth is not all at one uniform temperature, much as a uniform land level would be no good to us either as it would all be flooded, just not as deeply as the deep bits are now.

Mike.