Richard Clark wrote:
On Sat, 21 Oct 2006 18:20:40 -0400, jawod wrote:

You know, I've always been puzzled by negative refraction. The basis of
positive refraction is that the speed of EMR (say light) decreases
within a given material. In negative refraction, the speed of light
INCREASES?

I guess as long as it is less than the speed of light in a vacuum, no
laws have been broken?

Hi John,

My first reaction too.

However, when you look at the math, negative refraction is, well,
negative. What you describe (and I initially anticipated) is the
ratio of speed of light and the phase velocity being less than one.
Not the same thing being discussed here.

Another expression for negative refraction is "left-handed."

Anyway, more grist for you to review at:
http://physicsweb.org/articles/world/17/5/3

Following Richard's informative links, there is a page on the Duke site
which answers the "velocity of light" question:
http://www.ee.duke.edu/~drsmith/nega...ndex_about.htm

Near the end, it points out the difference between the phase velocity -
which is what we usually mean by "the velocity" of light - and the group
(or energy) velocity. It's only the latter that is made negative, but
the transport of energy is still in the forward direction.



--
73 from Ian GM3SEK 'In Practice' columnist for RadCom (RSGB)
http://www.ifwtech.co.uk/g3sek