From: mcirvin@husc10.harvard.edu (Mcirvin)
Newsgroups: sci.physics
Subject: Re: Defining Photons
Keywords: Relating photons E=MC^2 criticism
Date: 26 Jul 92 19:28:19 GMT
Article-I.D.: husc10.mcirvin.712178899

snarfy@cruzio.santa-cruz.ca.us writes:

>       Your  criticism is noted and forwarded to my sources.  However my
>       personal evaluation is that you are missing the point.  When  the
>       word  ``particle''  is both applied to that which has no mass and
>       to that which does have mass,  we  must  seriously  question  the
>       choice of words used, for the sake of clarity ,if nothing else .

Okay... here's the point.  Even though photons have no mass, we call
them particles because they are things that carry energy and momentum
in discrete quantities, and they can be located (sometimes) within
a local region of space.  So even though they don't have rest mass, 
they act in some ways like little objects, so we might as well call
them particles. 

It's nice that you or whoever found a way to relate a quantity of rest
mass to the energy contained in the photon.  But this isn't a
necessary prerequisite to calling it a particle.

>       If you are a college professor , the taxpayers  or  students  pay
>       you to enlighten and clarify issues pertaining to your specialty.
>       Why then have you not yet found a word other than ``particle'' to
>       describe  that  which has no mass , to differentiate it from that
>       which does?.  

Because we don't regard rest mass as the essential property that makes
it proper to use the word "particle."  It's true that it doesn't satisfy
all the things we normally associate with, say, specks of dust, but we
think that it isn't so huge an extension of the term to merit scrapping
it.  "Phenomenon," which you suggest, is too vague.  *Anything* could
be a phenomenon.  No pre-existing word is there to fit the concept
exactly, and in this case it has been deemed better to bend an existing
word than to make up a new one.  

>       I think it's because some of you  would  prefer  to
>       confuse people rather than teach them. 

Please... *must* everything be a conspiracy theory?  I understand that
you were responding to a posting that might be interpretable as a
flame, but please don't fall into the trap of assuming that physicists
are committing intentional obscurantism, perhaps to hide Big Secrets
from the public.  Once you make that assumption you have excluded yourself
from the possibility of learning any more physics.  Physicists pick
words because, to them, they seem to fit concepts adequately, or
because they evoke desired images in the imagination, or just because
they like the sound of the word.  Sometimes the choice of words is
not the best, but any physicist who did this intentionally would
confuse her or his own colleagues to such an extent that the work would
be forgotten.  The terms used in good popular treatments are, by and large,
the same ones used in the scientific literature; it's not as if there
is some separate secret literature in which everything is spelled out
in plainer speech. 

In a bookstore, I recently saw a volume in which the author claimed
that general relativity was being made difficult to learn in a
concerted effort to keep people from using it to extract free energy
from the sun's gravitational field!  It made me very sad, and a
little frightened about the possible consequences of such beliefs
becoming widespread.  People who do physics *should* make an effort
to teach people about what they do, if only to counter speculation
that they're hiding something.  
 
-- 
Matt McIrvin  mcirvin@husc.harvard.edu 
Newsgroups: sci.physics