I do believe this particular misconception, that energy is a
substantial, locally conserved quantity, is a serious cognitive
barrier. I am not familiar with the canon of literature on
physics education research, but I can see the reality of this
problem by observation of what is being said in this group.
Many bright, well-educated physicists here evidently believe in
the reality of substantial energy. Dan, you evidently believe
in it yourself, given your citation of the mass increase
associated with internal energy increase. I too believe that is
a real (if practically unmeasurable) effect, but I certainly do
not explain it to my students in terms like Martin Gardner's.
I understand the energy to be a state function ascribable to an
isolated (or hypothetically isolateable) physical system. It
is exactly the same sort of state function as the entropy, but
of course it varies in different ways as the universe evolves.
If there were no such differences between energy and entropy it
would be unnecessary to formulate the two quantities. You have
not considered the great difficulty students have in learning
the simple meaning of the statement that entropy is a function
of state, an abstract thing that is utterly insubstantial -
*just like energy*.
Treating the energy as being substantial is the great cognitive
block to the student's later understanding of the entropy. Some
teachers even try to smooth this over by introducing the "flow
of entropy" as a helpful concept!
I apologize for my lack of ability in articulating what is to
me a simple conceptual framework. I do recognize that "reality"
is a property which is properly discussed by metaphysicists
rather than physicists, but I have never been a terribly proper
fellow. My lights on this are Feynman and Burke, and I believe
Dan and many others in this group misread the former and are
unfamiliar with the latter. I am sure there are other scholars
who have treated this subject and reached diverse conclusions;
I will not read them extensively before speking my mind. That
is neither my way nor the way of most physicists. It is not
because these ideas are unimportant that I take such an
unscholarly position, but rather because of something rather
like a religious revelation. I believe because I believe I
understand my teachers.