« Are you a physicist ? » Giuseppe Penone asks me during the opening of his exhibition at the Grenoble Museum in November 2014. A little surprised, I answer: « Yes, I am a professor of physics at the university and a researcher in nanotechnology. » He then asked me: « Could you sculpt a grain of sand ? »
« Essero vento » (Featured image) : for the first time, the couple of grains of sand takes place in the imprint of this hand inscribed in a fossilized trunk that has become mineral over time. This image is from the presentation of the exhibition “A Question of Identity” at the Marian Goodman Gallery in New York City from November 14, 2017 to December 22, 2017. Mariangoodman.com
I know his work Essere fiume (Being a river), for having seen these two large identical and neighbouring stones laid out on the floor of the Grenoble museum. One comes from the river, and the other is carved identically by Giuseppe Penone. Their vision is surprising, because logically, two stones in nature cannot be identical. Twin stones have never been seen before.
The observation of these stones and the question of their identity plunged me into the heart of essential questions for scientists. In physics, elementary particles are said to be indistinguishable, as are atoms and molecules. This indistinguishability, rigorous and perfect, is the basis, within the framework of quantum mechanics, of the stability and of the density of matter, that is the matter around us, and the matter of which we are made of. It also describes this brutal obviousness: objects do not superimpose themselves in space. They interact harshly during contacts. These are the very same contacts that shape the stones, the ones Giuseppe Penone reproduces.
When we assemble more and more molecules, we quickly lose sight of this elementary indistinguishability. Objects are unique and have shapes that depend on their interactions with the outside world, on their history. Irreversibility and singularity settle with dimension.
From Essere fiume to Essere vento
Essere fiume is the evocation of river water that carries, rolls, attacks stones and rocks, which it marks as time goes by. The wind lifts the sand, not the rocks. It makes the grains clash with each other and with the world, marking them over time and helping to determine their unique shape. This is Essere vento (To be wind).
With the grains of sand, Giuseppe Penone changes scale: he goes from stones to grains. He switches to the threshold of the visible. To explore the invisible world, below the threshold of perception, physics combines theory, experience and instruments. The idea here is to use this approach to sculpt below perception, to try to make two barely visible grains identical.
“What size for the grains of sand? »
The size of the grains determines the scales to be carved and the instruments to be used. So that’s the crucial question. At the Néel Institute (CNRS and Grenoble Alpes University), we are able to carve matter on a micrometric scale in just a few minutes. Let’s say on the scale of a hundredth of the diameter of a hair. I think I hear Giuseppe Penone add: « At the limit of the perceptible, of the visible. » For me, it’s clear: these are grains about 100 micrometers in size. So in printing, the visible dot at the end of a sentence is about 300 micrometers in size. We should be able to cut the grains of sand at these scales. At least I think so. As is often the case with scientific experiments, we can’t completely predict everything. At some point, you have to jump in and try.
The meeting with the scientists
Giuseppe Penone visits the Néel Institute. I believe that the current is flowing well with my colleagues. Finally for a simple reason: Giuseppe Penone is a sculptor. He always has to work materials in detail. The physics researchers at the Néel Institute play with the electrons of matter to study their collective behaviour, to understand and transform the transport of energy and information. The quantum framework of these studies often requires the use of materials at micro/nano scales. Some of the tools used by technicians and researchers come to cut, cut, abrade matter at these scales.
This meeting between arts and sciences is first of all a meeting between an artist, technicians and researchers who will work together to reproduce a grain of sand. But at the Néel Institute, nobody studies grains of sand. We obviously lack specialists in grains of sand. Cino Viggiani is a professor at the University of Grenoble Alpes and director of the 3SR (Soils, Solids, Structures, Risks) laboratory where grains of sand are studied in detail, from the single grain to the multitude. He and his young colleague Edward Ando know how to find their way through the immense diversity of sand grains, and also how to determine the three-dimensional shape of a single grain on a scale of a few micrometres by X-rays. Their assistance is essential to the success of the project.
The fall 2015 problem: a grain 1,000 times too small
To choose the grains, we use a small microscope connected to my computer. It allows us to look at the grains of sand in detail on the screen. You will then need a microscope and a screen to see the work on display. In this situation, what are we looking at: the grains or the screen? This screen… makes a screen and hides the grains! Impossible! The solution is obvious: you need a larger grain. Let’s say between 1 and 3 millimetres to be clearly visible to the naked eye. Simple and catastrophic. In volume, and that’s what counts when you come to cut it, a grain of this size is 1,000 times bigger than the previous one. Cutting a grain 1,000 times larger will take a time, if not infinite, then far too long to do so. In much scientific research, we are working on the edge of the impossible. That’s part of the game. Sometimes you get stuck and doubt sets in. You have to hold on, but a scientist doesn’t give up easily. Could this be a new common thread in the workings of an artist?
Micro-sculpture thanks to high-power lasers
What is the technique capable of removing material, in this case silica at the scale of a few micrometers, from a millimetre-sized grain of sand in a reasonable time, at the location of our choice? It is micro-machining. More specifically, laser micromachining: a beam of highly focused and very intense laser light destroys solid matter at the micrometer scale. We use the company MUL (for laser micro-machining) located near Toulouse. Christophe Carrière and Mathieu Gouhaut welcome us. After a few tests, discussions between us and exchanges with Giuseppe Penone, we appreciate more in detail the potential of this technique. And the more we advance in this collaboration, the more we are convinced that we will not be able to recreate an identical grain of sand in 3D. But who really can, regardless of the scale? Once we see the similarity, we will inevitably find differences. But this quasi-identical shape should show both the miracle of unique identity and the impossibility of really copying it. Based on this observation, in the fall of 2016, we will proceed to select the grains and their size with this powerful laser that will dig into the material where Mathieu Gouhaut, the machine’s pilot, is leading. We then arrive at this result: the grain cut next to the natural one, which are now at the heart of this work.
Specialists in laser ablation, geomechanics, physicists, we were the actors of this part alongside Giuseppe Penone. We know the limits of grain sculpting at the micrometric scale. Nevertheless, as the first spectators of this microsculpture, we were surprised and transported by these two small grains on the laboratory table.