# Is this what happens to heat physically when moving from HOT to LOW

by astralfx
Tags: heat, moving, physically
 Sci Advisor PF Gold P: 11,099 Conduction of thermal energy through a gas is due to 'mechanical' interactions between adjacent particles. That's what the standard gas model in kinetic theory is based on. The photons that come into play with molecular 'collisions' are virtual photons (Feynman's model of force mediation between particles). This is not the same as the IR photons which are passed during radiation and absorption at a long distance (as in the greenhouse effect etc.). Afaik, the transfer of heat through gases is described pretty well using kinetic theory. Although your idea must have some relevance.
 P: 678 I think the fact that heat travels down a temperature grade is purely statistical. Say you have region A emitting X amount of heat and region B absorbing 1/2 of it. Region B is hotter and so emits 2X, and region A absorbs 1/2 of that. So heat transfer from A to B is X/2 but heat transfer from B to A is X so the net transfer is X/2 from B to A.
P: 790

## Is this what happens to heat physically when moving from HOT to LOW

First of all, heat is not the same thing as infrared radiation. Heat is energy that has been randomly spread out among various degrees of freedom in the system. In other words, heat is not a single form of energy, but rather energy that has been split up among all of the available forms of energy, including kinetic energy of the molecules present (further subdivided into translational, vibrational, rotational), interaction energies, and radiation (such as infrared).

In most situations you might find on Earth, most of the heat transfer is through collisions between molecules and not through infrared emission.

So, a high temperature gas comes in contact with a low temperature gas-- the molecules in the high temperature gas are moving faster, bouncing around like crazy. Where they come in contact with the low temperature gas, they bump into each other and the fast particles slow down, and the slow particles speed up.

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