The Universe Symphony is an unfinished work by American classical music composer Charles Ives.
Intended to be a spatial composition for two or more orchestras, it is in three sections: Ives conceived the idea during the autumn of 1915 while he was staying in the Adirondacks of New York State, but he left it alone until 1923, when he returned to working on it.
It is a complex work, using 20 independent musical lines; each moves in a separate meter, only coinciding on downbeats eight seconds apart.
Ives envisioned the work being performed by multiple orchestras located in valleys, on hillsides and mountains, with the music mimicking "the eternal pulse ... the planetary motion of the earth ... the soaring lines of mountains and cliffs ... deep ravines, sharp jagged edges of rock".
For more information see James B. Sinclair's "Descriptive Catalogue" of Ives's music and manuscripts (1999).