Nox Mater


The MEP (Maison Européenne de la Photographie), located in the historical neighbourhood of the Marais in Paris, France, invited franco-italian artist Lorella Abenavoli and Quebec artist-researcher Nicolas Reeves to present a joint installation project on the theme ‘Listening to the Sky ». This project, called « NOX MATER : Study for Muons and Silence », will be presented for the first time in September 2007. The NOX MATER project explores the relationships between the notions of place and scale by investigating the potential of two unusual materials : darkness and silence. More precisely, it is an attempt to connect two places that are the diametrically opposed in terms of size and scale : the uterine matrix and the Universe as a whole.

1 – Description

In an old Parisian building, a staircase leads the visitor towards a small vaulted underground room. The walls are entirely covered with absorbing materials, making the room is almost anechoic. All the sounds and noises emitted by the visitors are instantaneously silenced. In this small underground place, darkness is total, silence is complete. After some time, the visitor gets used to the dark. He realizes that very faint sounds, very short and precisely oriented, cross the space. They are accompanied by blurred flickers, small luminescent halos that appear briefly on the walls. There is no echo nor reverberation. The lights and the sounds are instantaneously absorbed by the walls, and the room returns to darkness and silence. These events are not random. They are triggered by the passage across the room of ephemeral and very penetrating cosmic particles called “muons”. Created by cataclysmic stellar events, such as supernovae explosions, the muon testifies for the mass-energy equivalence and for the time dilatation that occur at relativistic speeds (close to the speed of light). It relays information that comes from unreachable regions, and evokes both the story of matter and the very nature of the space-time cosmic fabric. With the neutrinos, much more numerous but infinitely more difficult to detect, the muons are among the only particles able to penetrate below the surface of the Earth,

2 – Listening to the silence

The theme « Listening to the Sky » reminds the numerous attempts that have been done to convert in sounds the movements and signals of the sky, from Kepler and the Harmony of Spheres to the sounds of the rings of Saturn, from the roars of Jupiter, of the Sun and of the Milky Way to the faraway echoes of pulsars and quasars. Many examples may be found on the internet (see HYPERLINK "" and the radioqualia web site for real-time sounds). Many artworks have been created from them (i.e. « Le noir de l’étoile, composition pour pulsar obligé », Gérard Grisey and Jean-Pierre Luminet, 1999). As impressive as they might be, all these sounds tend to hide the fact that the intersidereal space is mainly made from void and silence. Despite their numbers and dimensions, the planets, the stars, the galaxies, remain infinitesimally small when compared to the spaces in which they evolve. Listening to the sky is listening to the deepest of all silences. The size of the cosmic abysses that separate the stars is frightening. Nothing moves there, and no sound can be heard. Each and every place on Earth, even the most usual, are small fragments of this incommensurable space that our planet crosses in its travel, and that does not carry any sound. Even if it could carry some, it will not send back any echo : there is no wall or object to reverberate it. The Nox Mater installation proposes an experience of this space by creating a place where sounds disappear as soon as they are emitted, like in the intergalactic space. The small sound beams triggered by the muons will not contradict this space, but will make it deeper – just like the stars make darker the darkness of the sky.

3 – Muonic showers

The sky is first and foremost made of silence, but each space fragment at every instant is crossed by myriads of almost undetectable particles travelling at nearly the speed of light. They come for old stellar quakes, from cataclysmic explosions, from primordial lights. They tell the fertilization of the cosmos by ashes of exploded stars. Some, emerging from the heart of a supernova, will join a nebulae from which a new star will appear, with is planetary cortege. Other, through their spectra, carry on impossible distances the secret of the composition of a faraway celestial body. Those which will meet a planet – such as the Earth – on their trajectory will trigger a series of events that unveil some of the most intriguing aspects of the cosmos, and of the relationships between time, space and matter. The impact between a high-energy cosmic proton and the atoms of the upper atmosphere is a good example. It generates the muons that are detected at ground level. Despite its considerable speed, the proton is not disintegrated by the impact, but its kinetic energy is transformed into a wealth of new particles, called pions, which immediately disintegrate in muons. These events occur at about 10-12 km above our heads. In their own time, the muons do not live long. Riding a muon with a chronometer, a very small rider would travel 2 microseconds before the particle disintegrate. According to the speed of the particle, this would allow him to travel about 600 meters – not enough to reach the ground. But the muon travels at 99,7% of the speed of light, which generates relativistic effects. For a ground observer who observes its fall, its time is dilated about 20 times. This allows it to travel about 12 kilometres, which is enough to penetrate under the ground before disintegrating into other particles. A single proton arriving in the atmosphere triggers a muon shower on several square kilometres. At ground level, they arrive at a rate of 100 to 200 muons by second. An horizontal hand is crossed by one or two muons by second.

4 – The detectors

There are several ways to build a muon detector. We will use a composite detector developed by the Aware Electronics company in USA, and which made by two Geiger detectors (normally used to measure radioactivity levels) joined by a coincidence detector. The two Geiger detectors are vertically aligned. When both Geiger detect an event at the same time, the odds are very high that a muon has crossed them : any other particle will be eliminated by their detection by only one of the detectors.

5 – The walls

The design of the absorbing wall will use a 2-layer wall made with absorbing panels. The inner face will be covered by cardboard boxes lined with mineral wool. The boxes will have different sizes and different orientations, so as to break and absorb as many frequencies as possible. Four bass traps will be installed on the walls and roof. The vault and floor will also be equipped with these boxes ; they will be hanging from a light wooden structure in order to echo the shape of the medieval stone vault. The floor will be covered with double-thickness cardboard boxes, packed again each other and filled with mineral wool. Then a large metallic grid will be placed above the boxes ; it will be covered by a second grid with much smaller meshes, then by a felt mat. This strategy, which has been validated by a specialist in acoustics, allows to create good quality temporary anechoic room with a limited budget.

6 – Lights and sounds

Twelve muon detectors will be placed under the floor, in rigid wooden boxes. They will allow between 10 and 20 detections by minute. The light halos will come from small chains of leds included on small resin blocks. They will light on suddenly, then their light will decrease progressively in 45 to 90 seconds. The effect will look like a drop of rain falling on a stone heated by the Sun, and which takes a few minutes to evaporate. The light will be very faint : in order to perceive it, the visitor will have to stay several minutes within the installation. The design of the sounds triggered by the arrival of the muons will constitute an important part of the project. We will work with very short fragments of human voices, very brief whispers whose travel in the room will follow the direction of the incoming particle. They will carry their own echo. The encounter of synthetically reverberated sounds with a wall that annihilate any reverberation will be the object of particular attention. All sounds will be emitted by special very-low dispersion speakers, a recent technology that allows the sound beams to be almost as precisely delimitated as a beam of light. Using them in an anechoic condition is likely to produce a high-precision structure of space : a visitor who stands exactly within a beam will perfectly hear the sound ; another one just besides may hear nothing at all. To our knowledge, this coexistence in a small space of zones of sound and silence has never been tried.

7 – Architecture, place and scale

This installation is directly in line with Nicolas Reeves’ former projects, in which scientific or technological concepts are staged in architectural installations with a sound or music component : the Cloud Harp, a meteo-electronic instruments that reads the height and density of clouds with a laser and a telescope,and converts them into sound and music ; it is housed in a small architecture derived form the geometry of a stratus ; Computer Architectones, small sculptures resulting from the evolution of digital chromosomes coding different musical pieces ; The Garden of Ovelynetrees, a piece transcoding into sounds and voices the decomposition of real oranges enclosed in a gold and resin sarcophage… It is also directly linked to the work of co-author Lorella Abenavoli, which brings to perception different undetectable phenomena (vibrations of the globe of the earth, sound of sap rising in trees…), and which has been exhibited in as prestigious places as the IRCAM, in Paris. The installation carries an architectural component which is an investigation on the notion of place. This notion is considered both at qualitative and topological levels. The materials that are used (space, silence, darkness) draw the negative of an architecture, an anti-symmetrical reflection of the main images associated with this domain (mass, light, sounds of life). The underground situation of the installation conveys an important symbolical load : the damping of the sounds by the mass of the walls and earth contributes to establish an anechoic condition, an is directly linked to a particular ambiance. It awakes many different images. Some are directly linked to the location of the place, others to its particular atmosphere. The quality of an underground silence is very different from the quality of a terrestrial or aerial silence. The mythical serenity of buried places, like these closed caves whose silence is never disturbed, is not unrelated to the eternal silence of the cosmic space. To go under the surface of the Earth is to go towards its centre ; it is getting aware of geological time scales, and of the planetary nature of these layers that underlie and carry all the places where our daily life occurs. Like a uterine matrix dug in mother-earth, the small basement transformed into a cave becomes a protection against the infinity and eternity of space : it shields the visitor against immensity. But this planetary nature immediately reminds the other end of the scales of the world, the scale of these huge spaces in which the Earth has been flying from billions of years. They can legitimately frighten anyone who, like Blaise Pascal, tries to grasp their dimensions. The presence of space is quasi immanent : it is revealed by these particles which cross everything at every instant, like small ghostly entities : « if everything is in the sky, there is some sky in everything ». The events triggered by the muons reminds the visitors the inextricable entanglement of all places, at all scales. The matrix is the smallest inhabitable place. The Universe, the larger of all places. The former evokes the origin of life, the latter the origins of the world. The installation propose an encounter of these two matrices, the most opposed among all the range of possible places, through these infinitesimal particles which travel unimaginably fast.