2001: A Space Odyssey United States Library of Congress and selected for preservation in the National Film Registry. A musical score was commissioned for the film and composed by Alex North, but Kubrick ultimately decided not to use it, in favour of the classical pieces he used as guides during shooting. These included Richard Strauss's "Also Sprach Zarathustra", Johann Strauss' "Blue Danube Waltz", and music by twentieth-century composers Aram Khachaturian and Gyorgy Ligeti. Toward the end of the sequence where the HAL 9000 computer is lobotomized, it begins to play the 1892 song "Daisy Bell (Bicycle Built for Two)" by Harry Dacre, which Clarke
Interpretations of 2001: A Space Odyssey machines". Kubrick was also confronted with the fact that, during the production of the film, the US and USSR had agreed not to put any nuclear weapons into outer space by signing the Outer Space Treaty. Alexander Walker in a book he wrote with Kubrick's assistance and authorisation, states that Kubrick eventually decided that as nuclear weapons the bombs had "no place at all in the film's thematic development", now being an "orbiting red herring" which would "merely have raised irrelevant questions to suggest this as a reality of the twenty-first century". In the Canadian TV documentary "2001 and Beyond",