Re: COLLISION 2

["Michael N. Monce" <mnmon@CONNCOLL.EDU>]

On Mon, 29 Nov 1999, Jim Green wrote:

> Look I have said many times that one is quite welcome to define any word
> any way one wants -- but surely we don't intend to learn physics from a
> dictionary -- However, once one defines a word one must then be able to use
> it in a conversation to communicate.

        But it continues to amaze me how many of my students speak English
:)


> As to photons:  If I believed that there is really such a real particle  as
> a photon, I might be able to discuss it, but I currently assume that a
> photon is one of those vagaries of physics language that we use because we
> really don't understand what we are talking about.

        I don't really know what a photon is either.  I chose "light"
specifically because of its unique position (non-QM physics) of having the
property of energy and also moving at c.



> What might be a good idea as well is to make it a list rule for those who
> must say "transfer" is to say "transfer (bank)" instead.  Then we would all
> understand the same thing. These thoughts are valid for all "properties" of
> something -- like charge, mass, blue, etc  -- none of which move
> independently without the "something".
>
> I am sorry I said that; now we will have to decide what "something" is --
> and, for that matter, what "is" is.

        I think we are closer in agreement than I made appear.  I
certainly do not think energy moves on its own.  And certainly when our
photon intereacts with an atom on the earth the fields within the photon
do work on the charges within the atom.  It does seem energy must "hitch a
ride on something" to get from one place to another.
        When putting energy on the same footing as charge, why do we speak
of "current"?  Is that not a transfer of charge across space per unit
time?  Can we not also speak of an "energy current" while recognizing that
the energy is a property of the thing that is moving (photon, graviton,
gluon, etc)?
        My point is that the sun has a calculatable amount of "energy".
The sun also produces "light".  And that light, whether as oscillating
fields, or quantization of those fields, has "energy".  Light moves (in
all frames). Thus, energy was transferred to the earth.
        In your bank analogy, physically dollar bills are not transferred,
but money is.  Like energy, money is a property whether a piece of paper
has that property, or the electrons in the wires have the property.
Nonetheless, money moved (via paper or electrons) from your account to
mine.  You are welcome to try this anytime.  I'll send my account number
:)

                                Mike Monce
                                Connecticut College