I am no physicist, let’s just get that out in the open, I'm just a guy with an interest in this area. One thing I have learned in my limited examination of the natural world is that things tend to exist in states of polar opposites, but of the same type, ie male and female, but both human; north and south (pole) in magnetics; positive and negative in electricity; the cycles of a sine wave etc. So why can't the same be said of heat and cold?
I have read the answers on this question that state that cold is merely the absence of heat. But to me this doesn’t adequately explain the phenomenon of feeling coldness radiate off of a cold body. Now before you just say, “this guy hasn’t read anything” I realize that the immediate answer will likely be that my hand feels the heat radiating from the external surroundings and the air temperature around it combined with the heat from my hand being reflected back to it from the same molecules of air around it, and when a cold object is placed near my hand, what I am feeling is the lack of heat being reflected from my hand and from the surrounding air and that the temperature difference I am feeling is the reflection of my hands heat and the air being cooled by the cold object. Basically like the heat from my hand (and the surrounding air temperature) is moving to try and raise the temperature of the cold object to an equilibrium.
Or maybe I butchered that explanation. But my question is: How does the current idea of radiant heat and the apparent improbability of radiant cold fare against Pictet’s Experiment? And has anyone tried to recreate the experiment under different conditions? In the original experiment, a reflective surface was placed behind the cold object, but what if the reflective surface was simply a flat surface? If a flat reflective surface was placed behind the object and then replaced with a parabolic reflective surface of the same size and comparable dimension/density, would a further decrease in temperature be recorded?
Here is a link to a previous discussion on the topic from another thread on this board
Best Answer
1) You might find this discussion of Pictet's experiment interesting, and it specifically answers your question about non-planar mirrors.
2) If cold radiation is physically real, then it ought to be possible to produce temperatures below 0 Kelvin (absolute zero), simply by focusing enough of them, just as a solar furnace can produce extremely high temperatures by use of a mirror. The fact that this does not happen ought to be a clue.