🚀 go-pugleaf

jl...@internetMCI.com wrote:
> 
> "John M. Aldrich" <figh...@cs.com> wrote:
> 
> >Of course, there is no known way to
> >slow down or speed up a photon.
> 
> Yes, there is. Hold a glass container filled with water in front of
> it.
> That is, I THINK that's a way to do it. Sound travels faster than
> light under water, so I'm assuming that the light slows down.

No, sound does not travel faster than light under water.  I don't know
where you heard that, but it just isn't true.  However, light does
"effectively" go slower in a medium.  That's because according to the
model, where any given material is made-up of a collection of molecules,
the light entering one side of a material gets absorbed and re-emitted
many times successively by many of the molecules in-between before
finally making its way out the opposite side.  This is what slows down
the transmission, because there is a small time between the time when a
molecule absorbs a photon (particle of light) and when it re-emits it. 
I don't know enough about radiation theory to come-up with a rough guess
at a figure though.  However, since the space between the molecules is a
vacuum, the light will move at its maximum speed (at "The Speed of
Light") from one molecule to the next, since the speed of light in a
vacuum is a constant.  That's what is meant by "the" speed of light
being a constant, meaning the speed of light in a vacuum.  And in light
of the above explanation (sorry, no pun intended) that's the *only*
speed it ever travels at.  Any other time when a photon can say to have
been "stopped" by a molecule, it really dosen't exist anyway, because
it's either just been absorbed or is just about to be re-emitted.

By the way, I just want to take this chance to point out my observation
that none of the newsgroups that this thread is so prolifically posted
to seems to have any relation to the topic.  Though it is a very
interesting topic, I'm sure you'd get a lot more informative answers on
any of the "sci.physics" groups or maybe even
"alt.sci.physics.new-theories".  Yes, I know, my crossposting of this
follow-up dosen't help much to reduce the very phenomenon I'm
criticizing, but I took the liberty of cross-posting this to those
newsgroups in the hopes that people get the message and the thread
migrates over there.

-- 
Catcha' later,
Paul.                             -
                     That was Zen - This is Tao
                                  -