"Gene Fuller" wrote in message
...
Mike Kaliski wrote:


Tom,

The speed of light in air is not vastly different from the speed of light
in
a vacuum. If photons were apparently travelling at 1.7 times the speed of
light in air, they clearly must have been exceeding the speed of light in
a
vacuum.

This result was observed using visible light. Current theory is usually
quoted as nothing can travel faster than the speed of light in a vaccum.
It
is probably more correct to state that objects with mass cannot exceed
the
speed of light in a vacuum. Photons, having no mass, are not necessarily
subject to this rule and seem to be observed travelling at superluminal
velocity under certain very specific conditions. If the photons are
tunnelling and travelling faster than light in a vacuum, it does not
necessarily mean that any laws have been broken.

One way of imagining a way in which this could happen is if a block of
material is energised to a high energy state. Photons are continually
fired
into the material and are absorbed one by one with atoms within the
structure absorbing each new photon. At some point, the material becomes
completely saturated and cannot absorb any more photons. When the next
photon hits and is absorbed, a shockwave propogates through the material
and
a photon is emitted from the opposite side travelling at the same speed
and
in the same direction as the original absorbed photon. Stability is
restored
and energy is conserved.

But, it is the shockwave that has propogated faster than the speed of
light
and it is not the original photon that entered the material that is
emitted.
The emitted photon will contain exactly the same properties as the
absorbed
photon and the two would be indistinguishable. So the photon appears to
have
been transmitted through the material at faster than light speed, but no
laws have been broken.

A Newtons cradle can help with visualising how this can happen.

Mike G0ULI


Mike,

You had me fooled. It appeared that you might actually know something. But
that response bent the needle on my bull**** meter.

73,
Gene
W4SZ

Actually that response is very credable, It is analogous to what happens
when electrons travel in a wire. Put an electron in one end of a wire and
one pops out the other end almost instantaneously even though the actual
speed of electrons flowing ththrough the wire is very, very slow.

Jimmie