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Tin Roof of Physics



On Sat, 30 Aug 1997, Rick Tarara wrote:

Calorimetry can be treated sucessfully with an 'energy flow' model.
What is the advantage to quashing such models?

Again with the Tin Roof of Physics: if we nail a small piece of rusty
metal in a particular place on our roof, it may make it impossible for us
to position a nice solid plywood sheet later on.

The power of physics misconceptions is that they partially fulfill their
intended purpose. They model a portion of reality. But their great
failure is that they take the place of much better models. If humans did
not cling so tenaciously to their acquired models, then misconceptions
wouldn't cause such terrible problems. What if students immediately
abandoned the heat/Caloric worldview as soon as they were exposed to
modern Thermo? Then there would be no reason to expunge heat/Caloric from
K-12 science. After all, heat/Caloric is more easily learned, and it does
explain quite a bit about thermodynamics. As soon as it needed
replacement, this could be quickly performed.

But we humans build worldviews like masons build brick walls. Once a
particular brick is in place, many more bricks are placed on top, and
there's little chance that we are going to go back and disassemble the
whole construction just to root out one flawed brick. It takes huge
numbers of discrepant events and man-years of harangues by our teachers to
convince us to begin such an undertaking. If later courses of bricks are
all distorted, and if the building keeps collapsing, only then will we
make the effort to fix our foundation concepts and begin anew to rebuild
our entire worldviews.

heat/Caloric is a flawed brick. It works OK as long as one doesn't intend
to add too many courses of bricks above it. But if one intends to become
a physicist, then heat/Caloric and its vast assortment of networked
concepts will act as a barrier. For students who intend to enter science
as a profession, it MIGHT be better if they had never heard of "Heat
Flow." But for the rest of the world, we cannot expect them to take the
rigorous future-physicist courses, or to do without.

The situation could be better, but it's not that bad, because future
physicists are being trained as "masons" and "tin roof architects". I
would expect that it WOULDN'T harm a future scientist to learn
heat/Caloric, since that student is intending to become an expert in the
juggling of interlocking, sometimes contradictory concepts. How many
bricks can a mason keep in the air at once, if he/she has a part time job
as a street performer? ;) Don't even the thermodynamics experts fall
back on "heat flow" descriptions when needing to solve trivial problems in
the everyday world? But they know exactly the extent of application of
the Caloric worldview, its flaws, and the more advanced concepts which
replace it. These sorts of skills are the goal of the student-scientist.
So, at least for these people, the teaching of "misconceptions" might have
minimal harm and even occasional benefit. They are SUPPOSED to be tearing
up their tin roofs and brick walls all the time, while looking for
improved building materials, lucky fits, and beautiful patterns formed by
particular combinations of disjointed parts. And the difference between a
Feynman and the rest of us involves just how much of our constructs we are
willing to tear down and rebuild during our spare moments.

Lest we get too self-important, I must also point out that modern
Thermodynamics is itself a flawed brick. Just wait a few hundred years.
A couple of major physics upheavals will have taken place by then, and
what we now understand about Thermo will be seen as misleading enough to
be modified in fundamental ways. Caloric was found to be deficient, and
it was replaced by something that performed the same functions but more.
History shows that this is a continuing periodic phenomenon, and given
enough time will happen to any physical paradigm. We should never become
too proud of contemporary understanding, since someday it will be a
misconception which acts as a stumbling block for future students.
Scientists of the previous century should have adopted this view, no? And
scientists of the next centuries will look at our own pride with dismay,
as they try to expunge our "advanced concepts" from their poor students
heads.

P.S. can anyone give me the attribution and proper wording of the
following quotes? (I think one is Feynman, the other Einstein.)

If you cannot describe something in five different ways, then you don't
understand it.

If you cannot explain something to your grandmother, then you don't
understand it yourself.

Both pertain to this thread. If we cannot explain advanced Thermo to high
school students, to say nothing of grandmothers, then we should take a
hard look at our own concepts. And if we only have one accepted way to
describe a thing, then we are in danger of slipping into the misconception
that our description is REAL. But if we know several worldviews which
cover the same thing, then we won't be prone to the religious fervor of
defending one of these views as if it were the only correct explanation,
and all others must be wrong.

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