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?

I know very little about optics, but the velocity factor of EM waves in
hollow waveguide is always greater than one, that is, the phase velocity
is always greater than the speed of light. In fact, it increases as the
frequency lowers, approaching infinity at the cutoff frequency.

What prevents it from breaking any laws is that the group velocity,
which is the speed at which any change or information can be sent, is
always less than the speed of light.

I suspect that negative refraction is related to this, but will leave it
to the optics experts to say for sure.

Roy Lewallen, W7EL