Metastasis or Metastaseis ("dialectic transformations"), is an orchestral work by Iannis Xenakis, a Greek composer-architect and a major figure in the postwar development of musical modernism worldwide. He is particularly remembered for the pioneering use of stochastic mathematical techniques in his compositions, including probability (Maxwell-Boltzmann kinetic theory of gases, aleatory distribution of points on a plane, minimal constraints, Gaussian distribution, Markov chains), game theory, group theory, Boolean algebra and Brownian motion.

Metastasis was inspired by Einstein's view of time (a function of matter & energy) and structured on mathematical ideas by Xenakis's colleague Le Corbusier. The 1st and 3rd movements don't have a melodic theme to hold them together, but rather depend on the strength of this conceptualization of time. The 2nd movement does have some sort of melodic element. A fragment of a 12-tone row is used, with durations based on the Fibonacci sequence (1,1,2,3,5,8,13,21,34...)

The preliminary sketch for Metastasis was in graphic notation looking more like a blueprint than a musical score, showing graphs of mass motion and glissandi like structural beams of the piece, with sound frequencies on one axis and time on the other. In this video I tried to display this by presenting the frequency spectrum (0-20.000Hz) of the piece and how Xenakis actually "drew" music.

SWF Symphony Orchestra
Hans Rosbaud, conductor
October 1955

(YouTube description)

Wiki page: http://musiccaptioning.wikispaces.com/Metastasis+%28Spectral+View%29

See also http://musiccaptioning.wikispaces.com/space/content?tag=music+visualization (i.e. the pages tagged "music visualization" in the Music Captioning team's wiki) and in particular, another visualization of Xenakis' Metastasis in http://www.universalsubtitles.org/videos/QzCbHhCCF8LV/info/iannis-xenakis-metastasis/