Oh, this is just awesome, from a geeky reference frame: The case of the 500-mile email
“What’s the problem?” I asked.
“We can’t send mail more than 500 miles,” the chairman explained.
I choked on my latte. “Come again?”
“We can’t send mail farther than 500 miles from here,” he repeated. “A
little bit more, actually. Call it 520 miles. But no farther.”
(There’s a factor of two that’s not explained in the story, for round-trip vs. one-way, but still …)
The refractive index of fiberoptic core is around 1.48. Square root of copper cable insulation dielectric constant is in that ballpark, as is coaxial cable,
http://en.wikipedia.org/wiki/Velocity_of_propagation
One light-millisecond is 983,571 feet or 186.28 miles 3 light milliseconds would be 558.84 miles. With a fiberoptic RI of 1.48, 380 miles. Plenum data cable tops off around 0.72 lightspeed for 402 miles, good coax at 0.79 lightspeed for 440 miles, ladder line at 0.95 lightspeed or 530 miles. The story is marginal unless they were wierdly connected.