Dividing by zero is prohibited, and the penalty is severe
The Aegis cruiser USS Yorktown (CG-48) was commissioned in 1984. For twenty years, until its decommissioning in 2004, it was one of the most powerful and sophisticated warships in the US Navy. The continuing quest for sophistication, though, almost did it in. In 1996, the Yorktown was selected to be the testbed for Navy’s Smart Ship program. The cruiser was heavily computerized, with an integrated control center on the bridge and other computers monitoring all shipboard activity. The computers were all tied together into one network. On September 21, 1997, the cruiser was operating solo about 100 miles off Cape Charles, Virginia. A crewmember in the engineering department, while ordering supplies, mistakenly entered a zero as the divisor in a mathematical equation. Dividing anything by zero results in an infinite number. The computer crashed. That caused all the other computers on the ship to crash. The ship totally shut down. Not only did the engines not work, neither did the radios. The ship could not send an SOS or notify its headquarters of the dilemma. It took approximately 2 and ½ hours to get the radios back on line so that a message could be sent to headquarters in Norfolk. Assistance was dispatched and the cruiser was escorted back to port. The Navy immediately declared the whole incident secret. It was not until some months later that a report of the computer crash appeared in a technical publication. The Navy then acknowledged the incident, stating that the Yorktown had experienced “an engineering local area network casualty.” Needless to say, the Smart Ship program was extensively revised.