A "Doomsday Machine" refers to a theoretical device designed to cause widespread destruction, often in the context of nuclear warfare. The concept suggests that such a machine could automatically trigger catastrophic events, like launching nuclear weapons, in response to specific conditions, ensuring mutual destruction in the event of a conflict. The idea gained popularity during the Cold War, particularly with the development of nuclear deterrence strategies. It raises ethical questions about the control of powerful technologies and the potential for unintended consequences, highlighting the risks associated with automated systems in military applications.