Elementary Particle for Heat?

[Meandering Atheist -J-]

Heat in the sense physicists use it is nothing but energy that is randomly distributed in a material or collection of particles. If you have a gas, the heat it contains is just the random motions of all of its molecules.

I like this explanation. Heat usually gets explained as the kinetic energy of all the particles. Although this explanation isn't quite right (I forget what the more sophisticated definition is), it gives pretty good intuition. As you remove particles your gas gets colder... etc.