Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: electric charge



Larry Cartwright wrote:
but I am compelled to object to the
19th century characterization of electrical charge as a "substance".

OK.

Is not electrical charge a *property* of the elementary particles

Yes, fine.

For that matter, most of the things we deal with in physics are
"properties" in this sense: mass, length, temperature, et cetera.
Charge is no better or worse than the others.

which make up what we call substance,

Actually "substance" is a somewhat vague term.

To me, calling charge a substance is like insisting that blue is a
substance, or foul-smelling is a substance or strangeness is a
substance.

That's an interesting mix of examples.

I suspect nobody really thinks charge is a "substance" (whatever
that is) but they might say that charge is _like_ a substance,
and then they get misquoted.

IMHO their is a profound and beautiful and useful idea running
around here, namely the concept of a conserved quantity.
++ A substance such as water obeys a local conservation law
if only ordinarly low-energy physical processes are involved.
++ Charge obeys a local conservation law.
++ Energy obeys a local conservation law.
++ Lepton number obeys a local conservation law.
++ Strangeness obeys a local conservation law.
-- Blueness does !!not!! obey any such law.
-- Foul smelliness does !!not!! obey any such law.

Learning proceeds from the known to the unknown.

Most people (not including young children) can visualize or be
taught to visualize the conservative flow of a substance such
as water. From there it is a relatively small step to visualize
the conservative flow of charge and/or energy and/or whatever.

No analogy is perfect. Charge shares _some_ of the properties
of a substance such as water, but not all properties. But
imperfect analogies are often useful.