From: "JACK L. URETSKY (C)1998; HEP DIVISION, ARGONNE NATIONAL LAB ARGONNE, IL 60439" <JLU@HEP.ANL.GOV>
Date: Mon, 13 Sep 1999 00:55:48 -0500
Hi Cliff-
If you are careful about definitions then there is usually very little
room for argument. If you define your words consistently then you may say
almost anything, and your statement will be true.
You write:
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Why would it be incorrect to say that waves (any kind of wave) are made of
energy.
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Maybe you are being too general here. A sound wave in the air can
be ascribed to energy transfer by the air molecules - no problem. Is there
meaning to generalize this statement? Maybe, if you are careful enough in
you generalizing statement.
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Just as we would say that the earth is made of mass? ----- As I
wrote this last question I think I may have begun to see what you have been
saying. It occurred to me that we actually describe tangible things like the
earth to be made of matter and the amount of that matter we describe as mass.
If that is the case then energy is describing the amount of something. What
would that be? --- The amount of "ability to do work!"
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Well, why not? The energy that is transferred by a sound wave can
certainly do work by, say, breaking an expensive goblet.
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If I have things right here then mass describes the amount of matter just as
energy describes the amount of work that can be done. If GR is correct and
E=MC^2 (energy and mass are somehow interchangeable) then wouldn't matter and
the ability to do work also be interchangeable?
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False analogy. Mass is to matter as energy is to ?. Mass and energy
are the numerical results of measurements. Measurements on what? Matter is
the "what", in the case of mass. You must be specific in stating what it is
that you are measuring, in the case of energy.
Comment: Physics teachers need to be good teachers of their native
language. Why? Because the subject matter of physics is the communication
of our understanding of the world around us. We communicate with our students
using ordinary language. That is our tool, and we need to learn to use it
well.
Regards,
Jack
"I scored the next great triumph for science myself,
to wit, how the milk gets into the cow. Both of us
had marveled over that mystery a long time. We had
followed the cows around for years - that is, in the
daytime - but had never caught them drinking fluid of
that color."
Mark Twain, Extract from Eve's
Autobiography