Etienne Klein

On the occasion of the 400th anniversary of Galileo’s discoveries
As part of the international Year of Astrophysics

The Speaker

Born in 1958, Etienne Klein is a physicist with a PhD in the Philosophy of Science. He is currently the director of the Research Laboratory for Material Science of the Commission on Atomic Energy (CEA).

He is also professor of the Philosophy of Science at the Ecole Centrale de Paris. In addition, he is a member of the Scientific Council of the Cité des Sciences et de l’Industrie [largest science museum in Europe], of the Scientific Council of the Parliamentary Office for assessment of scientific and technological choices and of the Council of Analysis of the society presided over by Luc Ferry.

A specialist in the problem of time, he has written several discussion works on physics, including L'Unité de la Physique [The Unity of Physics] (PUF, 2000), Les Tactiques de Chronos [Chronos Tactics] (Flammarion, 2007), Petit Voyage dans le Monde des Quanta [Short Journey into the World of Quanta] (Champs-Flammarion, 2004), Il Etait Sept Fois la Révolution: Albert Einstein et les Autres [Once Upon Seven Times There Was The Revolution: Albert Einstein and the Others] (Flammarion, 2007).

In 2008, he published two new works, Galilée et les Indiens: Allons-nous liquider la science? [Galileo and the Indians: Will We Liquidate Science?] (Flammarion) and Les secrets de la matière [The Secrets of Matter] (Plon). 

In 1997, Etienne Klein was named the winner of the Jean Perrin Prize, awarded by the French Physics Society. In 2000, he received the "Budget Prize” from the Academy of Moral and Political Sciences, and the Grammatikakis-Neumann Prize, given by the Academy of Science. In 2001, his work L’Atome au Pied du Mur [Calling the Atom’s Bluff] won him the prize for best work of scientific literature of the year, and in 2004, he received the Jean Rostand Prize for Petit Voyage dans le Monde des Quanta, as well as the “La Science se livre ”[Science Opens Up] Prize for Les Tactiques de Chronos.


Galileo Is the Name for What?
Galilée et les Indiens [Galileo and the Indians], Flammarion 2008

The year 2009 will be the international year of astronomy. It will commemorate the winter of 1609-1610 when Galileo used an astronomic telescope to observe the uneven character of the lunar surface, and then the phases of Venus and Jupiter’s satellites.  The sky no longer appeared as the perfect, smooth, immutable sphere which it had been believed to be up to that point. The savant proposed the renunciation of the Aristotelian distinction of the world.
Galileo discovered that there was a “universe”, and one single universe! As for the Earth, it is no longer simply the center of the world, but a planet turning around the sun, like others, also accompanied by moons similar to our satellite. The rest of the story is well known: Galileo’s wrangles with the Church, his trial before the Saint-Office in 1633, his condemnation to renounce his opinions on the earth’s movement and the end of his life in reclusion, in physical and mental suffering.  His writings closed him off from scholarly Europe. Everyone certainly recalls the stakes of the final jousts: reason vs. faith, knowledge vs. institutional power.

Galileo played out what might be considered to be the primordial scene of modern science for which he has become the dominant symbol. In fact, he established the theoretical and experimental bases for modern science. His own discoveries were certainly decisive but were even more than that.  His way of thinking about nature with the help of mathematical equations opened up an extraordinarily fertile epistemological breach. It is precisely this point which Etienne Klein intends to discuss.

Will We Be Able To Travel In Time?
Le facteur temps ne sonne jamais deux fois [The Time Factor Never Rings Twice], Flammarion, 2007
Les Tactiques de Chronos, Champs-Flammarion, 2007

“Time is an agile eagle in a temple,” wrote Robert Desnos. An eagle which, of course, reminds us of Prometheus: he devours a liver down to the entrails which constantly grows back, invariably accomplishing the same task, without ever finishing.  Without a doubt, an agile eagle, since it is always evasive, never letting itself be caught or trapped (and also because agile is the anagram of eagle [in French]). With respect to the word temple, close to the word time, it translates the hieratic character of time, which does not itself evolve but makes the world evolve.

This evocation, albeit brief, opens a number of doors, mobilizes powerful symbols, and makes the imagination soar. But we note, without taking anything away from its charm or force, in fact rather the contrary, that it manipulates and associates contradictory notions, especially those of invariance and mobility.
The possibility of travelling in time is regularly mentioned in scientific magazines (and sometimes even by scientists themselves) and is the subject of numerous science-fiction novels.

We will first discuss the meaning that can be attributed to the expression “travelling in time” and then we will clarify what contemporary physics has to say on the subject.

The “Conquerors of the Minuscule” And the Elucidation of the Mystery of Black Matter
Les secrets de la matière racontés en famille [Secrets of Matter Shared in the Family], Plon, 2007
Petit voyage dans le monde des quanta, Champs-Flammarion, 2004
Il était sept fois la révolution, Champs-Flammarion, 2007

During the second half of the 20th century, the “conquerors of the miniscule,” the particle physicists, made spectacular progress. They were able to establish a sort of theoretical masterpiece, the “standard model”, which has completely resisted all experimental tests conducted to this day.

In the years to come, the particle accelerator LHC (Large Hadron Collider), a sort of enormous “sensory prosthesis”, will lead to the most conclusive discoveries. The high-energy proton collisions produced in this machine (27 km. in circumference) will, in fact, provide access to a new, virgin world, the conditions of which have not yet been explored in the laboratory.

Etienne Klein intends to scrutinize the questions which this machine might be able to answer, such as, where does the mass of particles come from? What became of the anti-matter which was present in the primary universe, at parity with matter? What is the composition of the mysterious black matter, which seems to have a gravitational affect on the galaxies but neither emits nor absorbs any light?

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