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Re: heat is a form of energy



Leigh,
Thanks for your thoughts. You raise more questions than you answer, but
that can be a healthy sign. Rather than going to your specifics, let me
now impose some of my thoughts on you, and let it rest.

I model neither energy nor charge as substances; they are calculated,
mathematical quantities - like scores that one tallies in a game. I have
exposed the pitfalls of energy reification in the past on this list.

However, I do find it useful to apply some of the properties of substances
to mathematical entities, either as metaphors or simply by recognizing a
commonly accepted widened use of certain words (institutionalized
metaphors?). For example, I find it more than a metaphor to apply the
ability to "flow" to any mathematical quantity which obeys the diffusion
equation. It is nigh impossible to express the content of that equation
without invoking a flow concept. This equation defines such a concept;
giving it the label "flow" does not thereby reify the flowing quantity, it
only gives us a useful visualization (we can only visualize substances,
not unattached properties).

"Velocity" is a sister word which certainly was also born as a property of
substances, but whose metaphorical applications have long since been
institutionalized in: "phase velocity", "group velocity", "cold front
velocity" etc. I do not count these latter phrases as metaphors; they are
now well defined, useful, technical terms and concepts with meanings of
their own, and do not of themselves invite unphysical conclusions (no
caloric spectre here; but there are pitfalls in eg., "moving
electrostatic fields", or - worse - the velocity of a thing relative to
an electrostatic field!).

As you say: "Physics holds no truths about Nature. The best we can do is
to construct our best descriptions of Nature . . ."

And the raw materials for this construction are derived from our sensory
perceptions of corporeal substances. In our model construction we have
learned to invent incorporeal, mathematical entities. We can
mathematically define the properties of these mathematical entities, but
in order to speak of them and visualize them we perforce (and always with
some risk) turn to the properties of corporeal substances. (1)

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

(1) Feynman on Conceptual vs Mathematical Models:

"Sometimes I wonder why it's possible to visualize or imagine reality at
all. . . . It's easy to imagine, say, the earth as a ball with people and
things stuck on it, because we've all seen balls and can imagine one going
around the sun - it's just a proportional thing, and in the same way I can
imagine atoms in a cup of coffee, at least for elementary purposes, as
little jiggling balls. But when I am worrying about the specific
frequencies of light that are emitted in lasers or some other complicated
circumstance, then I have to use a set of pictures which are not really
very good at all - they're not good images. But what are "good images"?
Probably something you're familiar with. But suppose that little things
behave very differently than anything that was big, anything that you're
familiar with?

Animals evolved brains designed for ordinary circumstances, but if the gut
particles in the deep inner workings of things go by some other rules, and
were completely different from anything on a large scale, there would be
some kind of difficulty, and that difficulty we are in - the behavior of
things on a small scale is so fantastic, so wonderfully and marvelously
different from anything on a large scale! You can say, 'Electrons behave
like waves' - no, they don't, exactly; 'they act like particles' - no,
they don't, exactly; 'they act like a fog around the nucleus' - no, they
don't, exactly. Well, if you would like to get a clear, sharp picture of
an atom, so that you can tell correctly how it's going to behave - have a
good image of reality, in other words - I don't know how to do it, because
that image has to be mathematical. Strange! I don't understand how it is
that we can write mathematical expressions and calculate what the thing is
going to do without actually being able to picture it. It would be
something like having a computer where you put some numbers in, and the
computer can do the arithmetic to figure out what time a car will arrive
at different destinations but it cannot picture the car. . . .

For certain approximations, it's okay. With the atom pictures, for
example, the idea of a fog around the nucleus, which repels you when you
squeeze it, is good for understanding the stiffness of materials; the idea
of a wave is good for other phenomena. The picture of atoms, for
instance, as little balls is good enough to give a nice picture of
temperature. But if you ask more, and you get down to questions like 'How
is it that if you cool helium down, even to absolute zero where there's
not supposed to be any motion, you find a fluid with no viscosity, no
resistance - it flows perfectly, and it isn't frozen solid?' Well, if you
want to get a picture of atoms that has all that in it, I just can't do
it. But I can explain why the helium behaves as it does by taking the
equations and showing the consequences of them is that helium will behave
as it is observed to behave, so we know we have the theory right - we just
don't have the pictures that will go with the theory.

I wonder whether you could get to know things better than we do today, and
as the generations develop, will they invent tricky ways of looking at
things - be so well trained that they won't have our troubles with the
atom-picturing? There is still a school of thought that cannot believe
that the atomic behavior is so different than large-scale behavior. I
think that's a deep prejudice, a prejudice from being so used to
large-scale behavior. They are waiting for the day that we discover,
underneath the quantum mechanics, some mundane, ordinary balls hitting
each other. I think nature's imagination is so much greater than man's
that she's never going to be defeated!" - Quoted in "No Ordinary Genius
...", Christopher Sykes