Shlomi Fish <

shlomif@...> writes:

> What if everything that connected these networks were fiber optics

> Point-to-Point lines? Maybe they have a close to vacuum light-speed.

There are two factors (at least) that affect the speed of

propagation. One is the material filling the fiber, and the other is

geometry. Just the second one would reduce the group velocity. The

material in fiber is some sort of glass. I don't know what its

refraction index is (anyone?). The refraction index of the ordinary

glass is about 4/3, meaning that the speed of light in the glass is

3c/4.

> BTW, from what I remember from my studies, the speed of light within

> certain materials can exceed the speed of light within vacuum, for some

> particular frequencies.

This can be the case for phase velocity, not group velocity, which is

the one we are discussing here (to make the long story short, it is

the one that determines how fast information can be transmitted by

light).

> Still passing information from one point to another

> can only be done at the speed of light.

Yep, and that's what matters.

--

Oleg Goldshmidt |

ogoldshmidt@...
========================================================

First binary search algorithm - J. Mauchly, 1946

First correct binary search algorithm - D.H.Lehmer, 1960