These days, telecom companies transmit phone calls in bits and pieces called packets, which enables them to pump a vast number of conversations through their wires at the same time. When you call someone in another city, your words are broken up and transmitted between computers at each end, which flick back and forth between one conversation and another, thousands of times every second. For that to work, however, the two computers have to stay in perfect sync, like a pair of incredibly nimble ping pong players who can hit the equivalent of a truckload of little balls at each other at blazing speed and never miss even one. If they do miss, the calls will get jumbled and sound like gibberish. That's why telecom companies these days have their own atomic clocks to prevent this from happening, by keeping the computers almost perfectly in step with one another at all times [source: Sciencemuseum.org.uk].