Re: refutation of the nonreality of energy

[Leigh Palmer <palmer@SFU.CA>]

Well, here it is. I hope someone is still reading me. Sometimes I
don't think I'm getting through.

At 03:22 -0700 8/3/99, John Denker wrote:

> At 09:53 PM 8/2/99 -0700, Leigh Palmer wrote:
> > in my rational realist philosophy,
> [the system has]
> > the property of reality, objective reality if you will. The system
> > exists independently of whether or not it is being observed, and
> > all observers can agree upon its extent and boundaries.
>
> OK.
>
> > The energy of this system has no objective reality whatever. It is
> > an abstraction, a quantity which has meaning and utility only when
> > one defines a frame of reference in which to reckon it. Different
> > observers may ascribe to the system different energies. Observers
> > in noninertial frames may even find that the system's energy
> > varies with time!
> >
> > I will point out that the size and duration of the system are,
> > likewise, abstractions.
>
> It seems there's been a swtich from "rational realism" to some sort of
> Platonism.  This passage attempts to make a very subtle distinction between
> "extent and boundaries" which exist and "size and duration" which are only
> abstractions.  To me, "extent" and "size" are synonymous for all practical
> purposes.

"From the back fence to the lakeshore" is an extent. The back fence
and the lakeshore are boundaries. "The distance from the back fence
to the lakeshore" is an abstraction. It can only be determined by
application of an operational definition which, when applied, turns
out to have a value which depends on frame of reference. This
dependence merely emphasizes the nonreality of distance, but it
would be unreal even if it were observer independent.

> I do recognize the distinction between vectors (which exist independent of
> coordinate frames) and the *components* of vectors (which depend on the
> choice of frame).  In the non-relativistic limit energy exists by itself
> and is conserved by itself;  in general it is part of a vector which is
> conserved and which exists independent of frame.

A red herring, but we've covered that.

> > Try to stop thinking of energy as being concrete. It is abstract
> > and will always be so.
>
> Energy is as real as distance.  Indeed, in a gravitational field, a
> measurement of height is a measurement of energy.  Most people agree that
> stones are real.  But the law of conservation of energy is stronger than
> the law of conservation of stones.

Energy is exactly as unreal as distance. Neither has a reality which
is independent of definition, or which exists independent of a system.

> And if you doubt the reality of stones, I refer you to Johnson via Boswell:
>
> % After we came out of the church, we stood talking for some
> % time together of Bishop Berkeley's ingenious sophistry to
> % prove the nonexistence of matter, and that every thing in the
> % universe is merely ideal. I observed, that though we are
> % satisfied his doctrine is not true, it is impossible to refute it. I
> % never shall forget the alacrity with which Johnson answered,
> % striking his foot with mighty force against a large stone, till he
> % rebounded from it -- "I refute it thus."

If you succeed in kicking energy I shall be very surprised.

> The typical person has more experience with stones than with pure energy,
> but that doesn't make one more real than the other.  Have you ever tried to
> land a plane, starting with too much energy?  A pilot's inventory of energy
> is as real and as important as a mason's inventory of stones.

Please tell me, what is "pure energy"? That is an entity with which
I am unacquainted, and which I believe does not exist. Can you tell
me how to prepare pure energy? If that can be done I will be most
surprised!

> Furthermore, at 10:39 PM 8/2/99 -0700, Leigh Palmer wrote:
> > [others] think of that energy as being distributed in space; and
> > potentially in all of space!
> >
> > If we can't agree on where this stuff called energy is, how can we
> > possibly ascribe reality to it?
>
> Field energy is distributed in space, but not in "all" of space.  It must
> be in very particular parts of space.  Energy is not just globally
> conserved, it is *locally* conserved, which is a stronger statement.  That
> is to say, it can't disappear from place A and reappear at place B without
> crossing the boundary (any boundary we choose) between A and B.

What is your evidence that it is "crossing"? (That is as bad as
"flowing" in my book.) Can you detect its crossing without asking
and answering the question "What changes in energy have occurred
in the systems on either side of the boundary?" I can detect the
flow of water. I simply place a little propellor in it and if the
water is flowing the propellor spins. I don't have to look on both
sides of a boundary to see which has gained and which has lost
water. Have you a comparable energy flow meter?

I have a small quibble with Jim which I will raise here. Jim said
charge doesn't flow; I disagree. I can make a propellor which
measures the passage of charge, a loop which exploits Ampere's law
to measure DC current. These can be purchased. They are called
"cliparound ammeters" (not like the cliparound AC ammeter which is
represented in one introductory textbook as exploiting Ampere's
law when it actually works by Faraday's law). Moreover, charge is
quantized. One can actually count charges, and the result is frame
independent. All observers agree on how many elementary charges
are present within the boundaries of a system. Electric charge is
real.

I hope this discussion helps exercise people to the point that
they have doubts about their understanding of energy. I believe we
are deluded by our teachers when we are young. They feed us caloric
theory and, because that is conceptually simple, we find energy
similarly simple. Why, then, do we have such difficulty explaining
entropy to our students? Entropy is exactly the same sort of
physical entity as energy. Of course it is not conserved, but so
what? We have perfectly well defined instructions for determining
its value given the thermodynamic parameters of any system.

Leigh