N-Polytope: Behaviors in Light and Sound After Iannis Xenakis is a dramatic light and sound environment combining cutting edge lighting, sound, sensing and machine learning technologies. The installation is a tribute to the Greek-French composer Iannis Xenakis’s radical 1960s-1970s Polytopes (from the Greek ‘poly’, many and ‘topos’, space), the first of which premiered at Expo ‘67 in the French pavilion at Montréal. As large scale, immersive architectural environments that made the indeterminate patterns and behaviour of natural phenomena experiential through the temporal dynamics of light and the spatial dynamics of sound, the Polytopes are relatively unknown still to this day but were far ahead of their time: a major landmark in the history of the audio-visual arts and performative architectural practice.

Originally developed as a commission for the LABoral Center for Art and Industrial Creation in Gijon, Spain in 2012, the installation has toured internationally and adapted site specifically in each location as it will be for Proximity Music: Echoes of Entropy. The installation consists of 150, powerful 10 Watt LED’s and many tiny loud speakers. These elements are suspended through the space on a geometric “ruled surface” constructed of thin aircraft cable, creating a light and sound environment which continually swings between order and disorder, akin to Xenakis’s original fascination with the behaviours of natural systems.

The installation is steered through a sensor network utilizing machine learning techniques which “learn” different rhythmic and temporal patterns produced by the light and sound and influence the overall compositional action over time. These computer algorithms are similar to what runs Google searches, robots or self-driving cars. Termed “reinforcement learning,” they involve software-based “agents” that interact with their environment in order to achieve some kind of goal and that are then numerically “rewarded” in either a positive or negative manner. The agent’s actions thus, influence not only the state of the environment in the present but also can affect it in the future.

In N-Polytope, the agents receive sensor-actuator information from the environment (the brightness of an LED or the amplitude of a sound, for example) and can perform simple actions. However, the environment around the agent (and the sensor) is continually changing, so it’s hard to determine what steps the agent will take and what they will result in. In this sense, the performance is evolutionary in that each action the agent takes may be different from the last.

Creating bursts of light as well as evolving patterns through these machine learning techniques, the self-organizing behaviour of the LED’s suggest Xenakis’s fascination with cosmological events, like the explosion of stars and supernovas. Counter-pointing the pointillist and minimal visual scenography, multi-channel audio from the small speakers as well as the larger environment fills the space, shifting between sparse natural and dense electronic textures. Across the architectural structure, the network of tiny speakers produce the behaviors of mass sonic structures made up of many small elements (sonic grains) creating swarms of tiny sounds that resemble a field of cicadas or masses of insects.

Termed an “electronic sculpture combining light, music and structures,” the original Polytope de Montréal for Expo ’67 emerged from a commission by Robert Bordaz, the curator of the French pavilion. Proposing a performative event consisting of an “interplay between light and sound through the available space and automated by computers,” Xenakis’s installation consisted of a Naum Gabo-inspired “transparent architecture” constructed from 200 gigantic steel cables, in lengths ranging from 21-30 meters and tautly stretched through the inner atrium of the French pavilion. Divided into five groups, each bundle of cables was instrumented with what Xenakis called “thousands of light sources” split in a corresponding set of five families of color: white, blue, red, green and yellow. Accompanying this was a six-minute orchestral composition diffused over four channels in the space.

N-Polytope is by no means a recreation of Xenakis’s 5 Polytopes created between 1967-1978, but rather a re-imagining that explores how Xenakis’s interest in probabilistic (so-called “stochastic”) systems can be made sense of and kept alive today using new technologies that were unavailable to the composer during his lifetime. In 2025, it will mark the 103th anniversary of Xenakis’ birthday as well as the 103th anniversary of the installation – which when it was premiered in 2011-2012, was already thinking about how Xenakis’ interest in probabilistic and stochastic systems to bring about a new universe of sounds an experience could be brought about by contemporary technologies of artificial intelligence. N-Polytope is thus an artistic response in grasping how Xenakis’s’ interest from more than forty years ago in modelling the behavior and patterns of nature and the cosmos in their exquisite fluctuations between order and disorder still powerfully resonates within our own historical moment of extreme instability in natural and artificial systems.