It is commonly cited by those who do not understand thermodynamics that IR energy (which they falsely call heat) can only move from a hot to a cold body.
Life is too short to try to explain why IR energy is not heat, heat is energy that is randomly spread through a defined system. IR energy is electro-magnetic energy in a specific band. The two overlap, but they are not the same …
So, first lets rewrite what we’re disproving in meaningful scientific terms from “heat only flows” to “IR only flows from a hot to a cold” and this is what I will prove is untrue.
Thought Experiment
Imagine two planetoids one hotter than the other. Each orbits a massive body with the same orbital period and the other body is so massive that one planetoid can only see the other for approximately half its orbit. Now imagine that the distance apart is such that in the time the light travels that distance, the planet has move 1/4 of its orbit. Now imagine that planet A, is 1/4 of an orbit ahead of planet B.
As Planet A comes around to the “right” side of its larger body, planet B is still 1/4 of an orbit behind on the “dark” side. But, by the time the light from planet A, planet B is just entering the “light side”. So all the light from A, arrives at B.
But now if we view the light from B. When B enters the “light” side, planet A which is 1/4 cycle ahead. But, by the time the light from B reaches A, planet A is entering the dark side of its larger sibling and as such, during the whole time planet B is emitting light, it arrives when A is blocked.
So, all the light from A heats planet B, but none of the light from B heats planet A. As such irrespective of the temperature IR (heat) energy only goes in one direction, from A->B. So, if A is colder than B, energy moves from cold to hot.
Disproving Heat only flows from hot to cold
Thought experiment: imagine many pairs of objects, one of the pair hotter than the other. We now bring them into contact so slightly that only one atom/molecule of each pair touch.
Statistically, more heat will flow from the hotter of the pair to the cold, but because heat is randomly distributed in a hot object, in some pairs, the atoms that touch will be colder than typical in the hot and warmer than typical in the cold, and therefore heat will flow from the cold to the hot.
How did I break the law? It was simple. Heat is ONLY a statistical property of a group of atoms or interactions, and I imposed a situation where there was only a single interaction. As such it is no longer “heat”, but instead is a form of energy or work. That is because heat is not a description of energy, but instead is a description of the statistics of energy distribution within a system. If it can’t be said to be statistically distributed or “on average this happens”, then the term “heat” is no longer appropriate.
Final Thoughts
Rather than planetoids, it should be possible to get matter which is spinning in some form which is only sensitive to light at certain phases of the spin. As such, it might be possible to align all the molecules and separate them at 1/4 of the spin cycle and offset the spin in each by 1/4 to break the law of thermodynamics.
