Philipp Oswalt (translated by Tas Skorupa) | 1991
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   Iannis Xenakisis' Polytopes

IIannis Xenakis - composer, engineer, and architect - worked in Le Corbusier's office from 1947 until 1960. In the following decades, based on his musical compositions and the architectural ideas which he developed together with Le Corbusier, Xenakis created several spatial compositions of light and sound which he collectively called 'polytopes.' This term is made up of the ancient Greek words poly ('many') and topos ('place'). Thus the title is to be understood as a designation for the staging of space in which spaces of light, color, and architecture overlap in one site.

Light Space

The Convent of La Tourette (1953 - 60) is not only the first project by Le Corbusier in which Xenakis's involvement was considerable. It also represents the synthesis and climax of Le Corbusier's previous works in the control of light and space.

In 1922, Le Corbusier had already stated that 'light and shadow reveal form,' (Textes et dessin pour Ronchamp, Le Corbusier, Swiss 1965) thus appropriating for light a function in the service of sculptural volumes. With the chapel at Ronchamp (1950 - 1953), this relationship began to turn around: the walls serve to modulate light. As Le Corbusier put it, the architectonic 'space becomes intangible.' (Das Buch über Ronchamp, Le Corbusier / Jean Petit, Stuttgart 1957, p. 46) The impression of space is created in a composition of light, half-shadow, and shadow.

Iannis Xenakis brought this spatial concept to completion in the design of the side chapel for La Tourette: he created a dark, intangible space. With so-called 'light cannons' he cut funnels of light from this undefined darkness. The space is no longer defined by the walls surrounding it. The perceived space is immaterial, and the immaterial spatial qualities take on a concrete quality themselves.

In designing the visual space of La Tourette, Le Corbusier and Xenakis not only worked with light volume, they also discovered the projection as a subject of architecture, creating projection spaces.

Projection Space

The church space which Xenakis and Le Corbusier designed together is a sort of camera obscura: the room is dark. A small square opening in the ceiling projects the image of the sun on the floor. The movement of the sun is represented by this wandering spot of light in the interior. Yet that is not all. The exterior walls of the lower floors of the monastery were designed by Xenakis as 'musical glass walls.' Also called 'ondulatoires,' they are composed of vertical strips of concrete and strips of glass of different widths. The constantly changing rhythm of open and closed is projected by the sunlight onto the floor. The floor becomes a projection screen. The walls fade in our perception. The projection of the rhythmical composition of light and shadow structures the space. With the movement of the sun, the picture changes.

While these projections of natural light are still reminiscent of the screens in Gothic cathedrals, artificial lighting and film projectors are employed in the Philips Pavilion (1958). In this second collaboration between Le Corbusier and Xenakis, the immaterial spatial qualities become the main subject of the entire design, as Le Corbusier himself states: 'I am not building the Philips Pavilion, but an electronic poem. Everything will take place in the interior - sound, light, color, and rhythm. Scaffolding will form the exterior of the pavilion.' (Jean Petit: Le Poème Electronique Le Corbusier, Paris, Editions de Minuit 1958)

Slide projectors with movable colored disks project changing spots of light onto the walls. Hundreds of colored fluorescent tubes and lamps simulate the course of the day - dawn, sunset, stars, and lightning. Projections of photographic images create spaces of illusion. The moving images of the four film projectors are dispersed in the space with the help of mirrors. The simultaneous projection of numerous motifs increases the effectiveness of the illusion. Due to the curvature of the projection surface, the projection becomes three-dimensional. The curvature makes portions of the image appear blurred and creates depth. This produces a three-dimensional space of illusion.

After his collaboration with Le Corbusier, Xenakis continued to develop the spatial concept of the Philips Pavilion with the polytopes he conceived on his own. In these spatial stagings, which he created between 1966 - 78, Xenakis abandoned the projection of figural, photographic images in favor of abstract compositions of light. He dissolved the projection screen into innumerable dots of light, like a television. This 'light image' is composed of thousands of incandescent lights which - mounted on a grid - surround the viewer on all sides. Moving, abstract patterns of waves, lightning, and spirals fill the space. There is also a three-dimensional projection - a light sculpture of laser beams whose spatial configuration is constantly altered by the movement of hundreds of mirrors and prisms.

As the abstract light compositions quickly change, the space is transformed at breakneck speed. It becomes dynamic. Time becomes the fourth spatial dimension.

Sound Space

Sound, like light, changes over time and describes an immaterial space, a bodiless volume. In the Philips Pavilion, over four hundred loudspeakers created numerous audio paths in which sound could be carried through the space slowly or quickly, erratically or incessantly.

The dispersal of multiple sound-sources throughout the space does not just make it possible for a tone to wander through the room. By projecting different sounds in different places there is an overlapping of many sound spaces. Each listener perceives the music in a different way according to his or her location at the time. The acoustical space is no longer homogeneous, but divides itself into different spatial areas. Xenakis developed this concept of spatially differentiated music for the first time in his orchestral piece Terretektorh (1965 - 66), written for an orchestra which is spread out in space. In the following year he used it in his first light-and-sound installation, the Polytope de Montréal. In this piece, four orchestras, represented by loudspeakers, make music on the different floors of a multi-storied space.

In addition to this, Xenakis developed in the following years a concept of temporal diversification of the musical space which is especially noticeable in his piece for percussion, Psappha (1975): in the temporal space, slow-speed low tones overlap with medium- and fast-speed high tones. Time is no longer absolute. Several time divisions and different tempi exist side by side, so that time oscillates.

Xenakis used this same process in the spatial stagings of his polytopes. In Le Diatope - designed for the inauguration of the Centre Pompidou (Paris) in 1978 - the music is almost static, moving in slow waves, while the flashes of light change at breakneck speed, in fractions of a second, and the composition of laser beams in turn has its own tempo. Time is no longer clear-cut. In the same way, the space is differentiated by projections of light and eleven speakers spread throughout the site.

Architectonic Space

The question must be posed as to which architecture is appropriate for such stagings of space. If it is not involved in the production, or if it only makes available the technical apparati, then it can be a simple scaffolding, a 'boîte à miracles,' as Le Corbusier called it as he had realized for the first time at the Paris Exhibition Pavilion of 1937.

With the Philips Pavilion, Le Corbusier and Xenakis had taken a different approach. Architecture became a modulator of space. The convex and concave curved surfaces form, as Xenakis described it, 'moveable, confining, receding, and turnable spaces.' (Gravesano Review, No. IX, 1957 p.44) For, in contrast to flat surfaces, curved or folded surfaces reflect the light with changing intensity and modulate the space. The space becomes dynamic, of changing intensity, concentrated and expanded. At the same time, its boundaries are removed. Walls and ceiling flow into one another. There is no defined enclosure on the sides, no defined closure above. The play of concave and convex curvature forms neither body nor space; it repels and embraces at the same time. The spatial borders can no longer be perceived by the eye in an unambiguous way; they disappear, as is also the case when the spaces are darkened. They appear to become infinite.

As early as 1902, this effect was discovered for the stage by Mariano Fortny. He developed the spherically curved dome horizon to mark three-dimensionally the back of the stage, creating the impression of infinity. The canvas envelops the stage without defining the space. Just like the round horizon which was created slightly later, the dome horizon creates an abstract stage space which only becomes concrete through light.

Even though Le Corbusier and Xenakis were probably not familiar with these innovations of the modern stage set, Le Corbusier had worked with similar means of staging space in his designs for dioramas (1925, 1929, and 1937). In a diorama, the image which has been painted on a transparent, curved canvas is made to appear by means of changeable lighting from the front and back. The change of lighting simulates the cycle of the day and movement in space. In order to be able to simulate wide, infinite exterior spaces, the borders of the closed interior are visually removed by the curvature of the image walls. In this way, the spatial form of Le Corbusier's pavilion for two dioramas at the Exposition de l'Esprit Nouveau of 1925 can be seen as a precursor of the interiors of Ronchamp and of the Philips Pavilion, the borders of which had been visually removed.

With Le Diatope, Xenakis went one step further: not only to the walls and ceilings disappear, but so does the floor. Since it is made of reflective glass, the visitor seems to float halfway up in the middle of the room. At the same time, the space of Diatope is opened toward the outside. The external shell is a semi-transparent membrane of red plastic which filters and modulates light, sound, and warmth. This rather passive filtering membrane is completed by an inner, active membrane - a metal net to which light and sound sources are attached. It is a building covering which does not delimit the space, but instead modulates it. While in the Philips Pavilion the covering of the building served to neutralize the surroundings and to mark off the limits of the interior and darken them, the double-layered membrane of Le Diatope is semi-transparent and its spatial effect can be controlled. It is a premonition of today's glass façades in which the permeability for each individual spatial parameter can be controlled independently for heat, light, and sound. The covering of the building is no longer open or closed. In-between tones or gray tones are possible. The space is no longer organized in masses and cavities, but consists of energy fields of different masses which contract and stretch the space.

From the Staged Path to the Scenario

By superimposing light space, projection space, sound space, and architectonic space, a multi-dimensional creation emerges, a diversified space of changing intensity and density. This space no longer allows itself to be designed with the traditional means of architectonic representation - floor plan, elevation, etc. Instead the architect has to devise other methods to be able to design and describe space, methods which illustrate the transformation of space over time and the cooperation of its different dimensions.

The first approach to this was developed by Le Corbusier in his design for a pavilion in the Exposition International Paris in 1937. He designed the space as a path. The actual spatial experience is set forth in a sketch by the architect which shows the procession of rooms in the interior of the pavilion through which the visitor has to proceed. The individual staged spaces are brought together with this design of the path, and the cooperation of the color spaces, projection spaces, and image spaces is coordinated.

In the Philips Pavilion the problems are much more complex: the space itself changes, and sound and film projections are added. Le Corbusier designed this 'electronic poem' by drawing scripts. These scenarios have vertical columns for the individual elements of the staging - colored light, various projections of images, etc. - and horizontal stripes for the temporal division, each indicating one second. The application of methods of film design makes clear the change in the understanding of space: instead of rigid bodies there is a changing procession of immaterial spaces.

Xenakis designed his polytopes with the help of scores. The individual 'voices' of the score correspond to different spatial parameters. Xenakis divided time into steps of 1/25 seconds, so that the turning on and off of the countless incandescent lights appears to the eye as continuous movement. To check this cooperation, Xenakis did not just make sketches of the individual spatial conditions, he also simulated the process with computers.

The coordination of the different elements of the production and its changes over time also present problems for their realization. It is no longer possible to manually control the large number of parameters. For this reason S. L. Bruyn, the engineer of the Philips' automation department, was asked to join the design team for the Philips Pavilion. Since modern computers were not yet available at the time, the program of the scenario, in the form of control commands, was transferred to a fifteen-track tape which made it possible for 180 switches to be made simultaneously, put into action with the help of relays and servo-motors. Xenakis perfected this control technique for Le Diatope. The 1200 light sources and the position of the 400 adjustable mirrors and prisms could now be changed every 1/25 second.

The projects of Xenakis and Le Corbusier were early pioneer works for a control technique which by now has been universally established in theater buildings. Theater sets are now controlled by computer - especially lighting, /scenery, and stage machinery. The script for all processes controlled by computer are stored on a floppy disk. The software is so flexible that it is not only permits manual intervention during the performance, but also a different tempo, thus allowing the play length to be extended or sped up by half an hour.

Open Staging

With his staging of space, Xenakis introduced a new concept of spatial design to modern architecture. Space is no longer primarily defined by its containing walls (border surfaces), but by its immaterial qualities of light, sound, and climate. These individual 'dimensions of space' are no longer synchronized, but are instead controlled independently. Light spaces, sound spaces, color spaces, and projection spaces overlap which are different from and contradictory of one another; thus, polytopes are created. The space is multidimensional, dynamic, and differentiated into areas.

Although Xenakis set down the entire process of these spatial 'spectacles' as closed compositions, in his musical works he was nevertheless concerned, on occasion, with the design of open structures. These compositions offer the perspective of open, interactive presentations which use the possibilities of today's technology of 'intelligent control' with flexible programs and scenarios to allow for reaction to the environment and the behavior of the user and to permit manual intervention. For such an open system Xenakis developed a concept of 'elastic borders,' which define the basic global conditions and within these conditions allows relatively wide flexibility in execution. Xenakis unambiguously demarcated this process of the domination of order over disorder from the concept of the total flexibility of musical expression and architectonic design: 'I do not believe in mobile systems, in an infinitely adjustable frame structure. (...) That liberty, that neutrality must be handled in such a way that the diversity created will be interesting. (...) Mobile architecture is nothing but garbage, because no one is able to replace an architect of worth. (...) One must create a space which is strong, rigid, but which nevertheless allows for a richness in arrangement, in the permutation of things and events.' (Perspectives of New Music, Volume 25, Summer 1987)

published in : Arch+ 107 | Aachen | 1991

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Links :

Iannis Xenakis Homepage
Iannis Xenakis Biography
A Tribute to Xenakis
An Essay about Xenakis by Alessandra Capanna: Architect of Light and Sound
A Discussion between Xenakis, Reynolds, Lansky & Machne