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Re: energy is real

I wholeheartedly agree with Paolo's rebuke of Brother Denker for his overly
harsh reply to Leigh. As one who has often been tempted (and, alas,
occasionally yielded) to respond testily to Leigh's pronouncements, I
recognize churlishness when I see it, and this was uncalled for.

poj

----- Original Message -----
From: "Paolo Cavallo" <ton0621@IPERBOLE.BOLOGNA.IT>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, March 16, 2000 1:51 PM
Subject: R: energy is real


----- Original Message -----
From: John Denker <jsd@MONMOUTH.COM>
To: <PHYS-L@lists.nau.edu>
Sent: Thursday, March 16, 2000 7:01 PM
Subject: Re: energy is real

1) Energy is real.

Would you care to defend this position or is it a pronouncement
*ex cathedra*?

That position can be defended in multiple ways.

First and foremost, usefulness: Some people find energy to be a useful
concept. If it's not useful to you, that's your problem. Please don't
inflict your problems on other people.

As a third party, I really can't understand the aggressiveness of this
message. I think
Leigh's question was quite civil! Even if I do not share his position, I
don't think he's
trying to "inflict problems"!

Is energy real? Are fields real? Is curvature real? Are laws real? Is the
absolute phase
of a quantum amplitude real?
I find these questions legitimate ones. They force us to think about the
meaning of "real"
in a scientific contest. Is this a case of "inflicting problems"?

Usefulness is a different matter. A lot of fictional constructs are
useful, like imaginary
planes in electrostatics. "Reality" is big business, and I think that your
attitude is
"unusefully" harsh.

a) Maybe you can show that the notion is wrong, perhaps by
demonstrating
a formal contradiction or inconsistency in the theory, or by showing
that
it makes a prediction that is inconsistent with experiment.
b) Maybe you have a better way to do the calculations that other
people
do using the energy notion.

Let us read Feynman again: "It is important to realize that we have no
knowledge of what
energy *is*. [...] it is just a strange fact that we can calculate some
number and when we
finish watching nature go through her tricks and calculate the number
again, it is the
same." We must say that to a certain extent energy is a human construct:
are human
constructs real? I suspect that physics has not yet an ontology good
enough to answer
similar questions, but we could work on that.

In either case, the burden is on _you_ to recruit believers by
demonstrating that you have a more useful way of doing things. Just
saying
no no no everybody else is wrong (without offering anything better) is
unlikely to bring many recruits.

Again: I find this passage harsh without needing. You seem to intend that
number and
consensus are relevant in physics: is this you're trying to say?

Another argument: My dictionary defines "real" mainly as the opposite of
fictional.

Ghosts are fictional; energy is real. If I write a fiction book about
ghosts, I can say pretty much anything I please. In contrast, if
I write a physics book about energy, I am very highly constrained as to
what I can say. I am constrained by reality.

Yes, indeed. The way I talk about energy when I talk of physical phenomena
contrains me.
But even when I draw a fictional plane in the space between two charges I
am constrained
by reality to draw the plane appropriately. The plane is no less
fictional. So, your
argument is not decisive. I can agree with you in saying that energy is
real, but your
argument is not a stringent one.

In this sense, energy and other abstractions have a more permanent
reality
than, say, hydrogen atoms do. If I have a box that is impermeable to
hydrogen, I can turn hydrogen atoms into something else (e.g. neutrons)
that silently escape from the box; the net result is that hydrogen
atoms
disappear from the interior without ever passing (as such) through the
walls.

This is a trick, isn't it? By the way, how do you do that?

You should try it some time: try to get rid of some unwanted energy in
a
hurry. If you think energy is fictional, if you think you can make
energy
disappear just by wishing, then your wishes are much more powerful than
mine. Please tell us all how you do it!

Energy is a construct we made exploring nature and trying to describe it.
So, it is
obvious we are constrained by reality when we use it! "Good" and "evil"
are much more
useful in communication and description of human reality than energy is.
Are good and evil
"real"?
The matter is bigger than you put it, I'm afraid. Leigh's ideas are useful
to deepen our
understanding of our own concept: I find no use in being aggressive.

Writing in English is hard work for me. Please forgive me if I have been
improper, obscure
or (God forbid) harsh to anyone.

Best regards,

Paolo Cavallo