Re: [Phys-L] Conservation of Energy vs Constant Energy

[John Denker <jsd@av8n.com>]

On 05/04/2015 11:03 AM, Paul Lulai wrote:

> I almost referenced that same section of Feynman.  However, he 
> mentions that there is a number and that number doesn't change.
>
> Well, for an open system, that number DOES change.  I fear 
> referencing Feynman will, in their minds, reinforce constancy.

That's true, and that's an issue ... but perhaps we can 
finesse the issue as follows:  The business of "constant"
versus "conserved" isn't the right starting point.

    *LOCALITY* is the crux.

Start with locality.  Feynman correctly makes a big fuss about 
locality.  A conservation law that's not local is basically 
useless ... and also inconsistent with special relativity.

Once you get that point across, you can spiral back around
and attack the open/closed issue again.  Constancy serves 
as a proxy for conservation in closed systems only.  If you
have an open system, you can define a new closed system
by enlarging your definition of "the" system ... but now
you have sacrificed locality, which is fatal.

> From this we conclude that the only way to get do the
whole job properly is to define a notion of conservation
that works for small, open systems.

  *Energy is conserved right here, right now.*

> Modeling physics addresses this, however, the group claims modeling
> physics is one of the sources of this incorrect and non-useful
> physics.

The PER literature is a veritable cornucopia of wrong
physics ideas, and there is nothing you can do about it.
This is why asking for an "authoritative" source is a
terrible practice.  The bad guys can always find an 
"authoritative" source for whatever nonsense they are
peddling.
  https://www.av8n.com/physics/authority.htm

If you want some real-world examples of people applying
conservation ideas to open systems, look in any work
on fluid dynamics, relativity, or (gasp) relativistic
fluid dynamics. 
  Misner/Thorne/Wheeler is a fine example, something 
  you might have on your shelf already (or really ought
  to get anyway).  The book looks impressive and 
  "authoritative", good for intimidating the peanut
  gallery ... but really I am recommending it for its 
  content, not its looks.