Subsequently, quantum theory also explained why a lower temperature/frequency/energy body cannot increase the temperature of a higher temperature/frequency/energy body, because all of the higher frequency quantum microstates of the hotter body are already filled and cannot be raised higher by lower energy photons from the lower temperature/frequency/energy body.
Although radiation between a hot and cold body is bidirectional, heat transfer is always one way only from hot to cold, as transfer of heat from cold to hot requires an impossible reduction of entropy (without work input) forbidden by the 2nd law.
Pictet's experimental setup was simple as shown in Fig 1 below and described in the following comment by Rosco:
|Two polished concave metal mirrors A & B focus radiation from a cold body C to a warmer body D [a thermometer], which causes a decrease in temperature of D below the starting ambient room temperature.|
The really funny thing is that centuries ago Pictet conducted an experiment in radiation using polished concave metal mirrors. Each mirror was placed far enough from each other such that conduction/convection played little part in the experiment.
He initially placed a hot object at one focus and a thermoscope at the other focus.
The thermoscope indicated a temperature increase due to IR. He allowed for equilibrium with room temperature to reestablish.
He then placed a cold object – a container of snow/ice at the focus and – viola - the thermoscope indicated a temperature decrease.
He introduced a “new” energy source – the flask of snow/ice – emitting say 235 W/sqm at say minus 18 C so remote from the thermoscope that the low conductivity of air played no part in either the hot or cold energy transfer BUT he PROVED that cold does not heat hot – quite the reverse occurred.
Modern physics explains this phenomenon by claiming the mirror screens the thermoscope from say up to 50% of the radiation from other objects in the room and the thermoscope is then radiating more to the flask than it gets back from the flask and hence decreases in temperature.
This explanation sounds reasonable but fails to account for the fact that the air around the thermoscope was unable to maintain equilibrium with the thermoscope?
BUT any way you care to spin this the radiation from a cold object always results in a decrease in temperature of a hotter object.
This has been known for centuries until climate science invented their fantasies.