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energy flows



At 09:19 AM 9/17/01 -0600, Jim Green wrote:

I continue to be disturbed at the archaic language of energy as a
substance -- One would think that physicists would try to say things
correctly. It is the business of a physicist to be precise -- We try to
teach our students precision -- Why do we cling to the past?

I never said energy _per se_ was a material substance.

I implied, and hereby state explicitly, that energy is a conserved quantity
and flows according to a local conservation law:
change(stuff inside boundary) = -flow(stuff across boundary)
This is one of the most elegant and most useful principles of physics.