Dark Side of the Moon is a concept album by the rock group Pink Floyd that explores the nature of the human experience through themes such as money, war, mental illness, and death. It is considered by many fans to be the band’s magnum opus. It is one of the best-selling albums of all time—it is estimated that one in every 14 people in the US under the age of 50 owns or owned a copy of this album. Many fans claim that the album’s music provides an alternative soundtrack to what 1939 film? Discuss