Mass and Energy to Gravity

[circa 1991]

Question: Every particle that has mass generates (or at least is associated 
with) its own gravitational field.  Matter, can be converted into energy.  
When that happens, what becomes of the gravitational field that was associated 
with that quantity of matter that has become energy?
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It turns out that gravitation does not depend directly on mass - 
it depends only through the energy (and momentum) of the matter involved.  If 
the matter changes in some way to reduce its rest mass, this has no effect on 
the total energy (or momentum) of the system, although it would certainly 
change the energies and momenta of the individual particles making up the 
matter in question.  This would have a short range effect on the gravitational 
field, but only in the way one would expect an explosion to have an effect.  
There would be no long-range effect because there is no net change in energy 
of the gravitating matter.

A. Smith
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