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If linear polarization can be described as a superposition of circular
polarization, and vice versa, how can one be more 'basic' than the other?
--James McLean
In the development you suggest above there is no limit to the
degree to which one may make "smaller" waves. It is not a quantum
argument at all.
This analysis is seriously flawed, principally because of a common
conceptual error. If one wishes to think about photons (and I will
usually be the last to adopt a photon model to explain physical
phenomena) then one must recognize that the components of a photon
are not themselves photons.
"Components" refers to the terms in a
linear combination of wave functions. These are mathematical
entities; they are not physical ingredients which one may combine
to form composite systems. The photon itself is an indivisible
quantum, yet its wave function can readily be expressed as a
linear combination of wave functions.
[Leigh]
OK. We adopt a photon model. (More on this later.)
Isystem = circularly polarized photon + ideal linear polarizer.
Polarizer is initially at rest; photon is propagating in direction
normal to polarizer. Photon has been prepared by dilution from a
beam of circularly polarized light and possesses nonzero linear
and angular momentum.
Interaction occurs.
Final states of system possible, both equally probable:
Fsystem1 = polarizer moving with initial linear and angular
momentum of photon. The photon has been absorbed by the polarizer.
Fsystem2 = polarizer moving with initial angular momentum of
photon, linearly polarized photon moving with undiminished linear
momentum.
The usual idealizations apply to these interactions.
Now I ask the question: what is the value of adopting a photon
model to explain this very simple wave phenomenon? It is not
difficult to do so, but where is the conceptual payoff? In what
way is this picture superior to the conventional picture? Is
there some inherently quantum mechanical aspect to the
phenomenon? In my opinion the gratuitous introduction of photons
encourages conceptual errors. Photons are a fine way to treat
the photoelectric effect; they don't help anyone to understand
polarizetion.
I apologize for not answering your previous posting of this
question, Brian. I was trying to remain consistent in my policy
of ignoring threads that were initially cross-posted to both
groups for no good reason (the POLARIZATION thread started that
way). I had changed the subject line to be helpful, but for some
reason you changed it back.
Others may not object to gratuitous cross-posting; I do. I don't
require that others share my feelings, but I reserve the right
to ignore such crosspostings.
Leigh