Re: heat is a form of energy

[Bob Sciamanda <trebor@VELOCITY.NET>]

I would assert that the statement that "energy is not localizable" is too
restrictive.  I would, rather, support the statement that energy is not
always UNIQUELY localizable.  For example, electrostatic energy may be
assigned using an energy density which is a function only of E ( and
non-zero only where E is non-zero), or the same total energy may be
assigned using an energy density which is a function of charge density
(and non-zero only where charge density is non-zero).  These two different
(and physically equivalent) allocations of "how much energy is where"
distribute the same total energy differently in space;  and both are
correct.  Either  (not neither) may be used - energy is localizable, but
not uniquely so.

Bob

Bob Sciamanda (W3NLV)
Physics, Edinboro Univ of PA (em)
trebor@velocity.net
http://www.velocity.net/~trebor

----- Original Message -----
From: crawford j maccallum <mccallum@UNM.EDU>
To: <PHYS-L@lists.nau.edu>
Sent: Monday, September 13, 1999 5:22 PM
Subject: Re: heat is a form of energy


> On Sun, 12 Sep 1999, Leigh Palmer wrote:
> > The ultimate way to calculate the charge on a system is to apply
> > Gauss's law to a bounding surface.    .......
>
> I was away this summer and was embarassed to get into this thread late.
> But it seems to be immortal, so may I venture a puzzlement that may not
> have been addressed specifically?
>
> If a nucleus absorbs a photon it gains energy and has a measurably
greater
> rest mass.  I always felt that the energy was now localized in the
> nucleus, where it wasn't before the absorption.  Although I agree with
> everything Leigh says, I still find it hard to let go of this feeling.
If
> the nucleus is replaced by a star, its mass can be measured by the
> curvature of space on a bounding surface.  Absorbing the photon changes
> its mass and therefore the local curvature of space.  It sort of seems
> the energy is now "inside the bounding surface"?
>
> Enlightenment, anyone?              Crawford