Greg writes on the perennial problem at the workplace named "interruptions." According to our friendly usability expert, it is a programmer's nemesis: one millisecond of interruption could disturb one's "flow," or nudge one out of his "zone."
Programmers produce their best code when they are in a 'zone' (others call it the 'flow'). During this stage, developers are fully concentrated in their work as if they are in their own universe. They lose track of time and forget that their last meal was 8 hours ago.