Just a comment on one point in Ingvar's last note: (01)
On mass:
> 3. You write: "and in middle school we learn that each kind of such
> particles has a mass which can be computed as the sum of the mass of
> its constituents." Not EACH kind of particle. Photons and neutrinos
> have no mass.
>
Photons have relativistic mass, though no rest mass; neutrinos actually have
a very small rest mass (according to the latest info I have). The "mass" we
measure is relativistic mass, and I don't think any distinction is required
in the units ontology (though it would be in an ontology of physics).
Relativistic mass is a very useful concept because it provides a simple
definition of 'physical object' as an Object (primitive concept) that has
some mass; that would include photons and any other fundamental particles
that have relativistic mass. (02)
Pat (03)
Patrick Cassidy
MICRA, Inc.
908-561-3416
cell: 908-565-4053
cassidy@xxxxxxxxx (04)
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