To: atm{at}shore.net
From: mdholm{at}telerama.com
Reply-To: mdholm{at}telerama.com


I find that I screwed up my discussion of Fermions and Bosons, so please
just disregard that.

Here is a link to a much more accurate discussion.

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/spinc.html

This website is aiming at a slightly different topic, solid state physics,
but that isn't all bad, since it starts to get close to things like the
quantum mechanical explanation of reflection of light by a metal.

As others have mentioned, if you put a detector in the area where beams
cross, you would detect interference.  Whether this constitutes
"interaction" is a question I am not really qualified to answer. 
In classical physics it is seen as the natural result of waves propagating
in different directions, at the same time through the same volume of space.
 In high school physics class, we had things called wave tables where you
could generate waves in water and watch their patterns and motions by the
shadows they cast.  It was possible there to show waves crossing without
affecting each other (except in the region of crossing).

In quantum mechanics, photons have a very low probability of scattering
each other (colliding), but at the moment I can't give the rationale.  (I
no longer think it is the spin value.)

I have read before of photon-photon scattering, a rare phenomenon predicted
by quantum mechanics in which light photons can scatter each other much
like the collisions of massive particles.  As I understand it, the
probablility of photon-photon scattering is so low that it has no practical
application in normal optics.

Mark Holm
mdholm{at}telerama.com

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