A lower bound for latency to the 'other side of the earth':
(20 000 km) / the speed of light = 66.712819 milliseconds
(20 000 km) / the speed of light = 66.712819 milliseconds
12,756.2 km / c = 42.5501031 ms
http://www.google.com/search?q=diameter+of+earth+%2F+the+spe...It's worth pointing out that we're looking at more like 0.65c, through optical fibre. This would also be ignoring routing infrastructure/processing time and network prioritisation.