Re: [Phys-l] Conservation of energy in nuclear reactions

[Spinozalens@aol.com]

In a message dated 5/1/2009 8:54:58 PM Eastern Daylight Time,  
carmelo@pacific.net.sg writes:

Quoting  John Denker <jsd@av8n.com>:
> Bottom line:  Energy is  conserved.  Period.  There are no known
> exceptions.  Of  course to make this work you need to include all
> forms of energy,  including the rest energy mc^2.

Energy could be "not conserved" in  general relativity depending on  
one's definition.

In  addition, energy could be "not conserved" in quantum physics when   
one applies uncertainty principle etc. :-)


Best  regards,
Alphonsus




))))))))))))))))))))))))))
 
Most Physicists maintain that energy is not conserved in GR. Strictly  
speaking you can't have energy conservation in an expanding space time, since  
energy is the conserved quantify that is related to time translation  
invariance (Noether's Theorem) which is not defined in a non static  Universe. Also 
if you sum over the total energy is any given O region you get a  divergent 
value. HOWEVER, you can do a very nice heuristic if you subtract out  the 
comoving frames for any given O region where you will  find that  for K=0 the 
total energy is zero. This is why you hear people like Hawking,  Guth, 
Stenger, etc., talk about a zero energy Universe.
 
In QT energy and momentum is conserved at each vertex of the Feynman  
formalism but you get an "uncertainty of measurement" because you have to sum  
over the higher order diagrams, a perturbative process. 
 
Bob Zannelli 
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