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- From: dk@imager (Dave Knapp)
- Newsgroups: sci.physics
- Subject: Re: Converting the masses
- Message-ID: <131638@lll-winken.LLNL.GOV>
- Date: 28 Jul 92 06:43:08 GMT
- References: <1992Jul22.193837.18095@sfu.ca> <mcirvin.711904014@husc8> <1992Jul27.191259.5549@sfu.ca>
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- Organization: Laboratory for Experimental Astrophysics
- Lines: 42
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-
- In article <1992Jul27.191259.5549@sfu.ca> palmer@sfu.ca (Leigh Palmer) writes:
- >In article <mcirvin.711904014@husc8> mcirvin@husc8.harvard.edu (Mcirvin)
- >writes:
- >>palmer@sfu.ca (Leigh Palmer) writes:
- >>
- >>Actually, neither definition of mass would be temperature-independent,
- >>if you define it for the whole lump of coal. When you raise the
- >>temperature, the energy in the rest frame increases! The sum of
- >>the masses of all the particles is perhaps temperature-independent,
- >>but as you complained before, that's not the mass of the lump.
- >
- >Exactly my point. The existence of an internal degree of freedom in a lump
- >of coal which affects its mass vitiates the particle physicists' definition.
- >Used outside particle physics this convention has no conspicuous advantages,
- >and indeed it may lead to conceptual problems of its own.
-
- As I said before, what you present as the "particle physicists'
- definition" is nothing of the sort. It would be very helpful to the
- discussion if you could not continue to promulgate this straw man.
-
- For example, the proton clearly has internal degrees of freedom that
- affect its mass; the only difference is that the mass spectrum is discrete
- and we give the various mass eigenstates individual names, so "proton" means
- the N+ particle in its ground state.
-
- No such distinction, however, is made in the case of atoms; the mass of a
- carbon atom, for example, depends not only upon the state of the nucleus, but
- also of the atomic electrons. In this case, however, we don't give every
- excited state of the carbon atom a different name. Even so, I think that every
- particle physicist would agree that the mass of a carbon atom is its energy
- in the rest frame.
-
- In other words, if you specify the state of your lump of coal sufficiently,
- then the definition of mass is unambiguous.
-
- -- Dave
-
- --
- *-------------------------------------------------------------*
- * David Knapp dk@imager.llnl.gov (510) 422-1023 *
- * 98.7% of all statistics are made up. *
- *-------------------------------------------------------------*
-