Experiments show that the minimum response time for interactive computing is around 70 milliseconds. This is the twitch response time needed by teenagers playing videogames or a person adding lip-synch to video.
Because signals travel a limited distance in 70 milliseconds, there is a finite twitch zone within which twitch response times are possible over a network. This zone has grown over the years, thanks to the introduction of fiber optics, which allow signals to travel at nearly the speed of light. At light speed, a signal can go a distance of 13,020 miles in 70 milliseconds. This is the greatest twitch zone possible.
It is just enough. The farthest distance between any two points on Earth happens to be about 13,000 miles. The planet is the perfect size for everyone to communicate with twitch response times.
