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[Phys-l] mass or rest mass?



Hello,

It was recently brought to my attention that numerous pages on wikipedia are espousing "mass conservation." See for example "Mass conservation", "E=mc2", and "Mass and energy in special relativity".

I wonder what everyone's reactions to these articles is.

My impression is that the physics is essentially accurate, but that the use of nomenclature is not so good. It was my understanding that modern usage in relativity is that "mass" means "rest mass", and thus that "mass" and "energy" are not two names for the same thing (as one of those articles claims). It is true that the (rest) mass and the non-mass-energy of one component of a system contribute equally and indistinguishably to the total (rest) mass of the whole system. But that isn't quite the same thing.

Cheers,
-- James
--
Dr. James McLean phone: (585) 245-5897
Dept. of Physics and Astronomy FAX: (585) 245-5116
SUNY Geneseo email: mclean@geneseo.edu
1 College Circle web: http://www.geneseo.edu/~mclean
Geneseo, NY 14454-1401