The score to Earle Brown's December 1952 is a single square sheet with straight lines of varying widths and lengths drawn horizontally and vertically.
My interpretation of the score, as I discussed it with Earle Brown, is that the lines in their non-specificity can be viewed as the two-dimensional representation of a three-dimensional space in which sound-objects, as if interplanetary bodies, are suspended. In that imaginary musical space, in Earle Brown's words, "the score [is] a picture of this space at one instant, which must always be considered as unreal and/or transitory." As the pilot of a musical space ship, we fly improvisationally through this space, turning to the right, left, back, forward, up, down, and all points between, encountering new sound-objects as we make every turn, affected perhaps only by "various forces."
An object is defined by its boundaries.
Earle Brown's December 1952 depicts the concept of an omni-directional sound-object universe. John Cage's Williams Mix, composed with Earle Brown in 1952, is a random sequence of sound objects, each object defined randomly.
John Cage Williams Mix
Edgard Varèse' Poème Electronique, composed for the Philips Pavilion at the Brussels World Fair in 1958, is one trip through Earle Brown's sound-object universe.
Edgard Varèse' Poème Electronique
Iannis Xenakis' ConcrètePH was played as entry-music for the Philips Pavilion.
Iannis Xenakis' ConcrètePH
Here is the pavilion.