The Doomsday Clock is a symbol that represents a countdown to possible global catastrophe. It has been maintained since 1947 by the members of The Bulletin of the Atomic Scientists' Science and Security Board, who are in turn advised by the Governing Board and the Board of Sponsors, including 18 Nobel laureates.
Originally, the Clock, which hangs on a wall in The Bulletin's office in the University of Chicago, represented an analogy for the threat of global nuclear war; however, since 2007 it has also reflected climate change and new developments in the life sciences and technology that could inflict irrevocable harm to humanity. The Clock represents the hypothetical global catastrophe as "midnight", and The Bulletin's opinion on how close the world is to a global catastrophe as a number of "minutes" before midnight.
The Clock's original setting in 1947 was seven minutes to midnight. It has been set backward and forward 22 times since then, the smallest ever number of minutes to midnight being two (in 1953) and the largest seventeen (in 1991). As of January 2017[update], the Clock is set at two and a half minutes to midnight, due to a "rise of 'strident nationalism' worldwide, United States President Donald Trump's comments over nuclear weapons, and the disbelief in the scientific consensus over climate change by the Trump Administration." This setting is the Clock's second closest approach to midnight since its introduction in 1947, after it was set to two minutes to midnight in 1953.
The Doomsday Clock's origin can be traced to the international group of researchers called the Chicago Atomic Scientists, who had participated in the Manhattan Project. After the atomic bombings of Hiroshima and Nagasaki, they began publishing a mimeographed newsletter and then the magazine, Bulletin of the Atomic Scientists, which, since its inception, has depicted the Clock on every cover. The Clock was first represented in 1947, when The Bulletin co-founder Hyman Goldsmith asked artist Martyl Langsdorf (wife of Manhattan Project research associate and Szilárd petition signatory Alexander Langsdorf, Jr.) to design a cover for the magazine's June 1947 issue. As Eugene Rabinowitch, another co-founder of The Bulletin, explained later,