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Re: heat is a form of energy

On Thu, 9 Sep 1999, Leigh Palmer wrote:

Explain to me how they are cognitively flawed. I'm unaware of any
problem there.

Newtonian mechanics directly implies that there are no "speed limits"
placed on relative motion, and also that time and mass behave in a
Classical manner. Therefor Newtonian mechanics is horribly misleading,
and we should not teach it. Instead we should wait until the undergrad
level, and then teach SR and GR directly, when no "Newtonian" concepts
intefere, or need to be unlearned. (Playing devil's advocate here. In
reality I think we should teach Newton's laws. And "heat". And also the
Bohr-orbital or "solar system" description of atoms. And then later
supply the information that lets students modify and extend these
concepts.)

I have never encountered the difficulty you see in teaching relativity
after Newtonian physics. I invariably encounter the difficulty with
previously learned energy misconceptions when I teach thermodynamics
students about entropy. Newtonian physics, in my opinion, sets up no
cognitive barriers to a student's progress; reification of energy does
so.


As usual, I have only myself as a guide, not experience with many
students.

When I first encountered SR back in high school, I found it to be deeply
abhorrant. It implies that TIME is not solid anymore, and that
SIMULTAENETY is all screwy. As a "Newtonian" thinker I simply could not
accept this. It would mean that I'd have to throw out everything I
understood about the physical world. But then I started to accept it, and
I simply came to the conclusion that Newtonian Mechanics was flawed, not
SR.

In what little I've read of the history of SR/GR, I see that my own
history was a miniature reproduction of the controversy surrounding
Einstein's ideas. They were abhorrant and blasphemous, and "who does this
patent clerk think he is, anyhow." There was a lot of screaming, but then
the tide shifted fairly quickly. Those who fought Einstein hoped everyone
would forget how wrong they were, and how emotional the whole episode was.
And then this aspect of the history of Relativity was rewritten, probably
because human beings prefer to think of themselves and rarely being wrong,
and prefer to think of themselves as instantly seeing the merit of all
strange ideas which come from left field and upset their long-held beliefs
about the nature of reality. Serious attempts to suppress/ridicule
Einstein were themselves suppressed and not mentioned in brief
science-text histories of Relativity.


"Heat" works fine as long as we remain extremely aware of its
limitations and of the misconceptions it can breed (no, I myself am
not yet totally aware of these. I'm still learning thermo and
trying to assemble an intuitive picture of entropy concepts.)

By implication you are telling me that "heat" works better than
"energy" in some application of the pedagogy. Please give me an
example; I can't think of one.


I see that "heat" is the same as "energy", within limits. Call it
"thermal vibratory energy" or call it "heat", and we communicate about
the same concept. I'm debating Jim Green in this thread at the same
time, and I suspect that he would strongly object to our replacing the
noun "heat" with the noun "energy" and therefore claiming that "energy"
flows from a hot object to a cold one.

You have not addressed the question I ask above.

I thought I had. If "Heat" is identical to "thermal energy", then our
choice between the "heat" and the "thermal energy" concepts are a
non-issue. However, because I had just been arguing with Jim Green, I
was (wrongly?) assuming that you did not accept "thermal energy
flows" as being a useful/proper description.

If you want to use the analogy why can't you say "energy flows"?

I can! I thought I was not allowed to say this. "Energy flow" is
being attacked too, but apparantly you aren't part of that fight?

If I may be allowed degrees of disagreement then I will say that I
object much less to the use of "energy" than I do to the use of
"heat" in this context. Introduction of a special term implies there
is a difference between "heat energy" and other "kinds" of energy.
I'm sorry, but that is a gross misconception with which many
students entering university are equipped (or hobbled).

If we eliminate the terms "sound" and "light", and replace them with the
term "energy", does this improve the teaching of physics? I'd say no. If
we eliminate "heat", and we instead say that "energy" flows from a hot
object to a cold one, I don't see this as a way to improve students'
understanding. It seems more like an attempt to be "right" in an absolute
sense, rather than an attempt to be "understandable."


If "sound" and "heat" and "EM waves" each are patterns by which energy can
propagate through a medium, then I see a need to differentiate between
them in my mind. The characteristics of these "flows" are controlled by
the media of propagation and the by frequencies involved. What conceptual
difficulties arise if I say that "sound" and "heat" and "EM waves" are
three different "kinds" of energy? Well, I might wrongly decide that
"heat particles" exist in the same way that Photons exist. Yet I would
not be so very wrong, because Phonons have many of the characteristics of
EM quanta, and they can be regarded as "sound particles" in many
situations. The "heat" which flows from a hot object to a cold one is a
mixture of "light particles" and "sound particles," or of "infrared waves"
and "hypersound waves."

We might accidentally communicate another misconception: the wrong idea
heat propagates in a way similar to that of coherent wave energy (light
and sound, for example). "Heat" instead propagates by a diffusion
process. It propagates not like a sound wave, but like a wave of blue dye
which spreads through the jar of corn syrup. If each atom in the lattice
is sending "heat" in both directions, then we aren't seeing
wave-propagation, we are seeing something more akin to the growth of a
crystal surface (where the opposing growth and dissolution processes are
almost equal.) This certainly is unlike normal wave propagation, yet by
discussing "heat" as being a form of energy similar to "sound," and
"light," we might unwittingly communicate the misconception that heat is
like a coherent wave.


Also, incoming students already understand "heat flow". If we ban the
word "heat" and give bad grades if they use it, then the students might
come to think that "thermal energy" is a different animal as compared to
"heat", and that two different types of energy exist here.

Do you believe there are different types of energy?

"ARE" is a problem! :)

Yes, I do use a mental tool called "different types of energy"... but then
I see that those "types" are not real, and they simply are part of the
"mental tool," and have no existence apart from it. If I use other mental
tools, then the whole "types of energy" concept never arises in the first
place.

"Types of energy" is a convenient shorthand which aids my understanding at
the simpler levels. When I take a microscopic view of matter, I see that
there is no "heat", or even any sound waves or EM waves. Instead there is
mechanical coupling and electromagnetic coupling between the mass-bearing
atoms in the lattice. All the macroscopic phenomena such as "sound" and
"IR waves" are Emergent patterns which only appear when we look at the
world in a certain way. When we twist our minds a bit, the "old lady with
the big nose" vanishes, and the "young woman looking away" takes her
place, yet not a single molecule of ink on paper has changed.



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