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Physics

@wpafb.af.mil
reply to 53059959

Re: Nice

said by 53059959:

no...? from the usa its a good 300ms away, thats just due to the raw speed of light limitation.

100mbps is great but all your content will be in chinese. if you try to download something from the usa it will crawl at 6mbps.
Equatorial Circumference of Earth: 40,075.02 km
Maximum possible distance to travel between two points on Earth (using most direct path): 40,075.02 km / 2 = 20,037.52 km.

Velocity of light in a vacuum: 3.00 * 10^8 m/s

Time for light to travel half way around the world:
Disatnce / Velocity = (2.00 * 10^4) / (3.00 * 10^8) = (6.667 * 10 ^ -5) = 0.067 ms

Therefore USA to Hong Kong, if points were positioned exactly half-way around the globe, the maximum time it would take (through "raw speed of light limitation") would be 0.067 ms...*not* 300ms.

Yes, there would be a greater lag than 0.067ms; however this is not due to the speed of light. Much of the lag would be accumulated within servers, switches and relays; also, signals traveling through copper travel substantially slower than the speed of light. Therefore, if any part of the journey were made on a non-fiber connection, this could help accumulate more lag.

Anyway, the "raw speed of light" limitation would only cause a lag of 0.067 ms. Light travels really quickly. Think a little harder the next time you want to dis' the blazingly fast speed of light.


lpmusix

@omcastbusiness.net

You say speed of light in a vacuum...genius, fiber isn't a vacuum, it travels at 75% the speed as it would in a vacuum (I believe, it's closer to that). There _IS_ 70ms of latency across the US over fiber, there's no way to get around it. So your .067ms or whatever from HK is crap



infintie

@cogentco.com

Actually I believe that it is slightly lower than 75%. Given a working number of 70% (a conservative estimate) we get a time of 9.54167619 × 10^-5 s. But another limiting factor being overlooked is that light in a fiber cable does not travel in a straight line. The principle that allows a fiber cable to work is TIR, which means that the light must be constantly reflecting off of the walls of the inner cable in the fiber (there are two concentric wires with different indices of refraction), which in turn means more lag, though it is still absurdly small.



Overtkill
Premium
join:2005-09-21
Magna, UT

Not to mention the additional latency issues inherent to connecting hardware and servers.