Photons propagate at 0.65c in fibre - the exact speed does vary depending on whether its single or multimode fibre. As I dimly recall single mode fibre is every so slightly faster. The equivalent EMR propagation speed in coppr is 0.75c And the EMR propagation speed in a vacuum is c (and according to Einstein it doesn't matter how fast you are travelling at the time.) Of course this assumes that anyone wants to know... Quite frankly I was having a good time listening to everyone blame thost nasty horrible slow routers for the missing 30ms. :-) Geoff At 08:05 PM 9/11/97 -0700, Vadim Antonov wrote:
Richard Irving wrote:
Light can travel around the world 8 times in 1 second. This means it can travel once around the world (full trip) in ~ 120 ms. Milliseconds, not micro....
You've got faster light than anybody else. The speed of light is about 300000 km/s _in vacuum_; that gives 134 ms arond the planet's equator.
So, why does one trip across North america take 70ms...
a) light is slower in dense media b) fibers are not laid out in straight lines (in fact, i saw a circuit going from Seattle to Vancouver via Fort Worth :)
70 ms RTT = 35 ms one way. Given that U.S. is about 50 deg. wide, it is abput 0.7ms/degree; or 250 ms around the world.
Less than 2 times slower than light in vacuum.
Hint, it is not the speed of light. Time is incurred encoding, decoding, and routing.
Hint: have a look at a telco's fiber map before spreading nonsense.
--vadim