Re: FLOW of energy

[LUDWIK KOWALSKI <kowalskil@alpha.montclair.edu>]

On 30 Aug 1997 Leigh Palmer <palmer@sfu.ca> wrote:

> > Please review Thompson's observation and explain it to us in terms
> > of the flow of "heat". Most of us think that it is a proof that 
> > "heat" is not a conserved quantity. 

Let me try. First, we must define words. I will use "heat" as a synonym
of internal energy. I know I am beatning my old drum but I was not yet
convinced that this is "bad physics". Work done on the shaft increases
the internal energy of the system (all metallic parts). For a very dull
bore we can have a quazi-equilibrium situation in which some radial 
distribution of "thermometer readings" will be established, for example,
90 C near the bore and 45 C near the surface of the cylinder. Why is it
wrong to say that energy flows into the colder air in the factory? Why 
is it wrong to say that heat flows from hot coffee to my hand via a
spoon? Or from the cooking oil to a chicken? Please answer; I am going 
to be saying these things to my students again, very soon.

I do not use the term caloric (or ether) in teaching; outdated models 
based on such fictitious substances no longer appear in our textbooks. 
By the way, it is only natural, as pointed out by Jim, that new teachers
are guided by textbooks and by practices with which they are familiar.
Why should thay reject tradition in favor of what some individuals are
saying on our list? It is not at all tragic when people do not take me
seriously. After all, I know I can be persuaded to change my mind. The
intellectual inertia (another collective phenomenon) protects physics.

OK, people used to say "flow of caloric". Why should this prevent me 
from saying "flow of energy" or "flow of capital"? The issue of energy 
FLOW is a new thread). Nobody responded to my questions from the last 
message. Let me repeat them.

1) What is the proper name for the quantities expressed in W/m^2 ? 
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. 

Unless it is accepted that "only fluids can flow" I see no problem with
the "energy flow" idea. A newtonian particle whose kinetic energy is
constant is associated with the motion of energy. Sound can also be 
described as a motion (flow) of energy. 
                                                     Ludwik Kowalski
P.S.
Jim, it may be useful if you give people the web address of your essay
on the first law. Everybody who is involved in this discussion of energy
transfer will benefit from it; I certainly did. But let me comment on
your recent message.

> ... the thread seems always to come to a point where the opposition 
> seems to say -- "Well, OK your view is 'correct,' but why can't we 
> keep doing what we have been doing anyway." ...
>
> I suppose one way to resolve this sort of impasse is to say OK you 
> don't post messages which imply that "heat flows" (which offends us) 
> and we won't respond with messages which imply that saying "heat flows 
> is stupid" (which offends you.)  Is that a deal?

There is no "opposition" on phys-L; each of us shares what he or she
thinks. That is what makes our list so good and so useful. Aren't we 
united in trying to improve teaching? But let us be realistic, arguing 
with phys-L-ers will not have a direct impact on what is deeply rooted 
in existing practices. I gave up looking at every new physics textbook 
for a statement that "charges on capacitors in series are not always 
equal".