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William Beaty wonders --
But if you have a quantity which obeys a conservation law, you then have a
"stuff," no? If you push it down in one place and it pops up somewhere
else, a "flow" has gone on between the two places.
Do you really think that it is helpful to our students to use language which
teaches that "energy" can be held in a bucket? Let me quote Leigh:
Another common error is made here which is much worse. Not only would an
antimatter-matter collision not result in an outburst of pure energy,
no such thing exists! Energy is an attribute of a physical system and,
as Feynman points out dramatically in his first volume of lectures, the
attribute itself does not have an independent existence!
You can't have a bucket of "red" -- you *can* have a bucket of "red paint".
It seems to me to be bad imagry to say that "red" is flowing from bucket A
to bucket B. While "red paint" surely can do so.
However, Leigh does tell me that he doesn't mind "energy flows" (nor
"entropy flows") These phrases make me twitch.
Further there is another facet of the physics which is blurred: For energy
to flow (twitch) from one body to another there *must* be work done by the
one body on the other. Don't you want your students to understand this?
Hey, folks, this is just one of those things I would never say in a
classroom. Other views may vary.