There is a clock at the University of Chicago called the Doomsday Clock whose time perpetually lingers just shy of midnight. On this clock, midnight metaphorically represents full nuclear war bringing an end to all civilization, and the clock is meant as a gauge to constantly indicate humankind’s proximity to this horrific event.
When it was introduced in 1947, it was set for seven minutes to midnight. Since that day, its minute hand has wandered around on the upper-left quarter of the clock face, inching closer to 12:00 when the threat of nuclear war grows, and crawling away as the risk fades. It has been as close as two minutes to midnight in 1953, and as far as seventeen minutes in 1991. If its caretakers ever set it for midnight, it will probably be the last thing they ever do.
The custodians of this clock have been the men and women of the Board of Directors of the Bulletin of the Atomic Scientists. The Bulletin is a publication which was founded in 1945 by many former Manhattan Project physicists, and over the years contributors have included Albert Einstein, Edward Teller, J. Robert Oppenheimer, Carl Sagan, Wernher von Braun, Al Gore, Isaac Asimov, and Arthur C. Clarke to name but a few.
The Doomsday Clock is a symbolic clock face, maintained since 1947 by the board of directors of the Bulletin of the Atomic Scientists at the University of Chicago. The closer the clock is to midnight, the closer the world is estimated to be to global disaster. The most recent officially-announced setting — five minutes to midnight (11:55pm) — was made on 10 January 2012. Reflecting international events dangerous to humankind, the clock's hands have been adjusted twenty times since its inception in 1947, when the clock was initially set to seven minutes to midnight (11:53pm).
In 1947, during the Cold War, the clock was started at seven minutes to midnight and was subsequently advanced or rewound per the state of the world and nuclear war prospects. The clock's setting is decided by the directors of the Bulletin of the Atomic Scientists and is an adjunct to the essays in the bulletin on global affairs. The clock has not always been set and reset as quickly as events occur; the closest nuclear war threat, the Cuban Missile Crisis in 1962, reached crisis, climax, and resolution before it could be set to reflect that possible doomsday.