In one of his postings yLeigh said that "the energy is not stuff. It
doesn't flow because it can't be localized, and treating it as stuff
leads to well-known problems (that's what the caloric model was)".
Jim also argued against the phrase energy flow. "There is nothing that
flows", he wrote. "There is no so called heat flowing! In fact there is
no energy flowing either! What happens is WORK IS DONE! In each case!"
He was referring to six mechanisms through which internal energy of a
gas could be increased in a container. Placing the container on a hot
plate was one of the mechanisms.
What is the proper name for the quantities expressed in W/m^2 ? What is
wrong with saying that energy flows from a broadcasting station to the
antenna of my radio set? Or consider a disturbance, for example a single
pulse, moving along a stretched slinky.
Jim's argument was that the so-called "heat flow" is really nothing else
but numerous transfers of energy from faster molecules in the plate to
slower molecules in the gas. Kinetic energy of gas molecules increases
(on the average) because work is done on them through collisions.
A very good observation. But what is wrong with saying that a large
number of individual collisions leads to a collective property - flow of
energy. It is like the law of supply and demand; the law does not apply
to individual transaction, it can only be used to understand some market
situations. I consider thermodynamics to be a macroscopic science. As
we all know, temperature and pressure are collective properties; these
concepts do not apply to individual molecular interactions.