Dystopias are often characterized by dehumanization, tyrannical governments, environmental disaster, or other characteristics associated with a cataclysmic decline in society. Dystopian societies appear in many fictional works and artistic representations, particularly in stories set in the future. Some of the most famous examples are Aldous Huxley's Brave New World (1932), George Orwell's Nineteen Eighty-Four (1949), and Ray Bradbury's Fahrenheit 451 (1953). Dystopian societies appear in many sub-genres of fiction and are often used to draw attention to society, environment, politics, economics, religion, psychology, ethics, science, or technology. Some authors use the term to refer to existing societies, many of which are or have been, states or societies in an advanced state of collapse.