Re: Light slows down in glass?

["Bob Sciamanda" <trebor@velocity.net>]

A correction:  it is not Omnes but Oseen who authored the "extinction
theorem" in 1915.  Born & Wolf also cite papers on the theorem by others
during the same time period, but his name is usually associated with the
theorem.


Bob Sciamanda   sciamanda@edinboro.edu
Dept of Physics   trebor@velocity.net
Edinboro Univ of PA  http://www.edinboro.edu/~sciamanda/home.html
Edinboro, PA   (814)838-7185


-----Original Message-----
From: Bob Sciamanda <trebor@velocity.net>
To: phys-l@atlantis.uwf.edu <phys-l@atlantis.uwf.edu>
Date: Friday, February 06, 1998 10:58 PM
Subject: Re: Light slows down in glass?


> Let me try another attack at this.  Start with a fixed point charge and its
> electrostatic field.  Now introduce a conductor into this space;  there
will
> be a transient period of time during which the mobile charges  in the
> conductor will be moved by the original field.  After the transient period,
> the original field of the point charge still exists everywhere, just as
> before, but there are now also the fields of the re-arranged mobile charges
> (which will exactly cancel the original field inside the conductor).  The
> net field everywhere is the superposition of all of these fields.
>
> Now repeat the scenario, except that the original source charge is
> oscillating and generating a wave into all of space.  Introducing matter
> into this ALREADY EXISTING field will produce secondary radiation sources
> out of each mobile charge IMMEDIATELY.  The original field still exists
> everywhere, and there will be a transient period during which the secondary
> and original waves superimpose into a steady state wave pattern whose PHASE
> VELOCITY is c/n (given a transparent material).  The "extinction theorem"
of
> Omnes (1915) examined this model in detail (Cf Born & Wolf's Optics book).
  ^^^^^^^
> Much like the phase velocity in a waveguide, this phase velocity can even
be
> greater than c!  It is only the "velocity" of a geometric pattern.
> -Bob