Wil McCarthy speculates on the physics of the One Ring.
The real power of the One Ring comes from its ability to command the other rings, and so enslave the elvish and dwarvish and human rulers of ancient Middle-earth. This is actually very easy to arrange: the Ring is simply the master node of a wireless network, and is able to send commands and receive telemetry from the other rings, including their locations and the spoken words of the people around them. The reverse is not true: the One Ring sends out no telemetry, and obeys no commands. It can't be tracked at all unless it is used, and even then its location cannot be determined except in vague geographic terms. Also, since this network is known to operate over thousands of miles, across many mountain ranges and such, it must have a satellite relay. This is supported by the fact that Gollum, who kept and used the ring in an underground lair for hundreds of years, was not detected. The satellite(s) also presumably play a role in tracking the other rings' locations, which is one of the specific powers called out in Sauron's campaign slogan.
