PORTRAIT

Fascination with the invisible

The well-known astrophysicist Jean-Pierre Luminet, research director at the French national scientific research centre (CNRS) Paris Observatory, certainly has more than one feather in his hat. The scientist is also a writer, poet, musician and artist, and loves to get up on stage as a ‘cosmology storyteller’. It is a talent that won him the 2007 ‘European Science Communicator of the Year’ prize in March 2008(1).

Jean-Pierre Luminet. «Ce n’est pas l’Univers tel qu’il est qui m’interpelle, mais tel qu’il pourrait être.» © Gallimard - C.Hélie Jean-Pierre Luminet. “I am attracted not by the universe as it actually is, but by what it could be.” © Gallimard - C.Hélie

The story might have begun in fairy tale fashion: once upon a time there was a little boy living under a southern sky where the nights were clear, who loved the stars and became an astrophysicist. However, the truth is more complex. Although Luminet was indeed born in the Provence region of France, he was not so much attracted by Ursa Major and Ursa Minor as the unfathomable darkness between them. “I have always been interested in the things we don’t see, in trying to understand the invisible architecture of the universe. As I wrote somewhere, I am attracted not by the universe as it actually is, but by what it could be.”

As a teenager, Jean-Pierre Luminet’s interests were very wide-ranging, including drawing, literature, music, philosophy, mathematics and much more. Although he retained an interest in all these different fields, it was perhaps his encounter with Greek thinking that would lead him little by little onto the path of science. “Without any practical resources, Heraclitus and Parmenides tried to free themselves from pure myth and to understand the universe rationally, whilst endowing it with poetic and metaphysical properties.” Parmenides’ cosmos is impenetrable, perfect, timeless, unchanging. By contrast, to Heraclitus harmony means perpetual change, transformation, movement. “All Western thinking, in both philosophy and scientific research, is a perpetual balance between the two extremes, these two great aesthetic views of the world.”

Black holes

Then at the age of 15, a little phrase he discovered in an astronomy encyclopaedia fired up his imagination. “I remember an article summarising the theory of general relativity in which the author explained that space could be seen as a mollusc.” This prompted him to choose mathematics a little later, which in turn lead him to study other types of molluscs – those revealed in the Gaussian equations – before opening up the world of cosmology.

The period was the 1970s: the ‘Big Bang’ theory was becoming the major reference for astrophysicists to explain the beginnings of the universe. Luminet was an enthusiastic follower of the little-known ‘Big Bang’ founder, Belgian priest Georges Lemaître, about whom Luminet later wrote a biography. “Not only was Lemaître the father of the Big Bang, he also had a premonition about the existence of black holes,” those mysterious and powerful vortices capable of sucking in all the stellar matter in their vicinity. In 1979, Luminet was one of the first to try to write a mathematical formalisation of the secret regions of space. “I used a computer to calculate what a ‘dressed’ black hole looks like. It can live alongside a star and attract the star’s gaseous matter, which it absorbs and causes it to burn fiercely.”

Jean-Pierre Luminet propels a golf ball or a billiard ball into a fishnet stocking to put across to an uninitiated audience the mechanism of these devourers of matter. No one is better than Luminet at telling the story of the primordial mini-black holes that formed at the same time as the Big Bang, stellar black holes created by the disintegration of massive stars, intermediate-mass black holes and supermassive black holes (several million solar masses) that are found at the centre of every galaxy, including our own Milky Way. “In this specific case, you can see how a black hole can shatter entire stars that approach too close without actually falling into the black hole. The stars flatten out before bounding away and exploding. This is what I have named ‘flamed stellar pancakes’, because the stars look as though they have been squashed before blazing very brightly. Telescopes have been able to detect such phenomena for a number of years now.”

Univers chiffonné

Another of Jean-Pierre Luminet’s personal hypotheses, which was subsequently supported by observation, is the concept of a ‘wrap-around’ universe (univers chiffonné). This metaphor aims to convey the idea that, even if the universe is not infinite, it knows no boundaries. Its very form is apparently so complex that it allows light rays to travel in various ways between two given points, acting like a hall of mirrors, with images from distant objects being repeated multiple times across the sky. This makes it possible to travel within it indefinitely, giving the impression of moving around a space that seems larger than it actually is. Similar to the interior of a sphere edged with 12 slightly curved pentagons joined together (a dodecahedron), this so-called ‘wrap-around’ universe is not unlike the Poincaré dodecahedral space (1906), invented well before the theory of general relativity or the discovery of the expansion of the universe.

“When I introduced this concept, it was met with scepticism from cosmologists.” However, in 2003, signs of its validity came from the observations of the United States National Aeronautics and Space Administration (NASA) WMAP satellite concerning fossil radiation emitted by the universe 400 000 years after the Big Bang. “While some physicists are very committed to a confirmation, others with a mathematical bent are more indifferent. I fall somewhere between the two. What I am interested in is exploring new avenues that nobody has considered before. If, on top of that, we were to have experimental confirmation, it would be the icing on the cake…”

Transference

Jean-Pierre Luminet moves from one discipline to another with greatest ease. “In the space of a few hours, I might do some equations, start writing a poem, continue an essay or novel and prepare a talk… However, I do see art and science as separate disciplines. I am wary of blurring boundaries, even though I realise that my esearch into mathematical physics advances my poetry and my writing in general.”

This nomad likes to travel from country to country and continent to continent to share with others the spirit of adventure of the astrophysicist explorers. In demand the world over, Luminet considers it essential to explain the universe not only to leaders and managers but to children as well. “I feel it is important to put forward the new concepts and different paradigms offered by modern science and so encourage all society’s stakeholders to take on board new ideas.”

Above and beyond science, he is interested in a cross-cutting approach, such as the relationship between science and art. “I try to analyse how the imagination of the scientist and artist functions, and to find parallels in history. If you take a scientific concept, such as the black hole, you see that archetypal thinking underpins it – the void that swallows everything… The concept is expressed in a variety of other forms too, such as the black sun of Rimbaud, Edgar Allan Poe or Max Ernst.”

Imaginative worlds

(Non-scientific) creation is also part of Jean-Pierre Luminet’s life. His drawings and etchings reflect his questions about space and some of his imaginary architectures bring to mind those of Dutchman Maurits Cornelis Escher. Music is without a doubt his greatest passion – he composes music, plays the piano, and collaborated with Gérard Grisey (a pupil of Messiaen and Dutilleux) to produce a piece of cosmic music called Le Noir de l’Étoile. This piece for six percussionists, magnetic tape and sound signals from a dying star, Vela, recorded by a gigantic radio telescope, received an award from France’s Charles Cros Academy.

Luminet has written numerous scientific essays, designed more to disseminate knowledge than to popularise science, as well as many novels, translated into various languages. His latest novel, La Discorde Céleste (celestial discord) is about two real but contrasting heroes, Tycho Brahé and Johann Kepler, whose intersecting lives and work were to lead Newton to use the law of universal attraction to explain celestial mechanics (2).

Is Luminet a jack of all trades? He is multi-talented to say the least. He has won countless awards in different fields. But perhaps Luminet’s favourite gift came from his peers when they named asteroid 5 523, discovered in 1991, after him. Although Luminet does not yet have a road named after him, he can already lay claim to a planet.

Christine Rugemer

  1. cordis.europa.eu/science-society/descartes/home.html

  2. For a list of Jean-Pierre Luminet’s diverse scientific and other works, in all languages, see luth2.obspm.fr/~luminet/. See also the CD on Jean-Pierre Luminet in the CIRCO collection, La recherche nous est contée, published jointly by Gallimard and the CNRS – www.cnrs.fr/cnrs-images/circo.

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