Laszlo Tisza and the two-fluid model of superfluidity
Publication date: Available online 10 November 2017 Source:Comptes Rendus Physique Author(s): Sébastien Balibar The “two-fluid model” of superfluidity was first introduced by Laszlo Tisza in 1938. On that year, Tisza published the principles of his model as a brief note in Nature and two articles in French in the Comptes rendus de l'Académie des sciences, followed in 1940 by two other articles in French in the Journal de physique et le Radium. In 1941, the two-fluid model was reformulated by Lev Landau on a more rigorous basis. Successive experiments confirmed the revolutionary idea introduced by Tisza: superfluid...
Source: Comptes Rendus Physique - November 10, 2017 Category: Physics Source Type: research
Brief history of the publications of the French ‘Académie des sciences’
Publication date: Available online 8 November 2017 Source:Comptes Rendus Physique Author(s): Olivier Hardouin Duparc This paper traces a brief history of the publications of the French ‘Académie des sciences’ since their beginnings more than three hundred years ago until today. After reviewing their evolution and various changes, especially for fifty years, it tentatively proposes a possible future for the current Comptes rendus Physique. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - November 9, 2017 Category: Physics Source Type: research
The discovery of radioactivity
Publication date: Available online 6 November 2017 Source:Comptes Rendus Physique Author(s): Pierre Radvanyi, Jacques Villain The radioactivity of uranium was discovered in 1896 by Henri Becquerel who, starting from a wrong idea, progressively realized what he was observing, regularly informing the French Academy of Sciences of the progress he was doing. In the next years, it was found that thorium was radioactive too, and two new radioactive elements, polonium and radium, were discovered by Pierre and Marie Curie, while a third one, actinium, was identified by André Debierne. The study of the penetrating power and of...
Source: Comptes Rendus Physique - November 6, 2017 Category: Physics Source Type: research
The Sagnac effect and its interpretation by Paul Langevin
Publication date: Available online 31 October 2017 Source:Comptes Rendus Physique Author(s): Gianni Pascoli The French physicist Georges Sagnac is nowdays frequently cited by the engineers who work on devices such as ring-laser gyroscopes. These systems operate on the principle of the Sagnac effect. It is less known that Sagnac was a strong opponent to the theory of special relativity proposed by Albert Einstein. He set up his experiment to prove the existence of the aether discarded by the Einsteinian relativity. An accurate explanation of the phenomenon was provided by Paul Langevin in 1921. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - November 1, 2017 Category: Physics Source Type: research
Dynamics of cracks in disordered materials
Publication date: May–June 2017 Source:Comptes Rendus Physique, Volume 18, Issues 5–6 Author(s): Daniel Bonamy Predicting when rupture occurs or cracks progress is a major challenge in numerous fields of industrial, societal, and geophysical importance. It remains largely unsolved: stress enhancement at cracks and defects, indeed, makes the macroscale dynamics extremely sensitive to the microscale material disorder. This results in giant statistical fluctuations and non-trivial behaviors upon upscaling, difficult to assess via the continuum approaches of engineering. These issues are examined here. We will see: – ...
Source: Comptes Rendus Physique - October 26, 2017 Category: Physics Source Type: research
The birth of wave mechanics (1923 –1926)
Publication date: Available online 25 October 2017 Source:Comptes Rendus Physique Author(s): Alain Aspect, Jacques Villain In 1923, in three articles published in the Comptes Rendus of the Académie des Sciences, Louis de Broglie proposed the concept of wave–particle duality. Physicists from many countries seized upon this idea. In particular, Schrödinger developed de Broglie's qualitative idea by writing down the equation that the wave must satisfy in the non-relativistic approximation. A relativistic version of this equation was proposed in 1926 by several scientists, and other ones found a solution to the Schröd...
Source: Comptes Rendus Physique - October 25, 2017 Category: Physics Source Type: research
Nuclear magnetic resonance in high magnetic field: Application to condensed matter physics
Publication date: Available online 18 October 2017 Source:Comptes Rendus Physique Author(s): Claude Berthier, Mladen Horvatić, Marc-Henri Julien, Hadrien Mayaffre, Steffen Krämer In this review, we describe the potentialities offered by the nuclear magnetic resonance (NMR) technique to explore at a microscopic level new quantum states of condensed matter induced by high magnetic fields. We focus on experiments realised in resistive (up to 34 T) or hybrid (up to 45 T) magnets, which open a large access to these quantum phase transitions. After an introduction on NMR observables, we consider several topics: quantum ...
Source: Comptes Rendus Physique - October 19, 2017 Category: Physics Source Type: research
Poincar é, the dynamics of the electron, and relativity
Publication date: Available online 18 October 2017 Source:Comptes Rendus Physique Author(s): Thibault Damour On 5 June 1905 Poincaré presented a Note to the Académie des Sciences entitled Sur la dynamique de l'électron (“On the dynamics of the electron”). After briefly recalling the context that led Poincaré to write this Note, we comment its content. We emphasize that Poincaré's electron model consists in assuming that the interior of the worldtube of the (hollow) electron is filled with a positive cosmological constant. We then discuss the several novel contributions to the physico-mathematical aspects of Spe...
Source: Comptes Rendus Physique - October 19, 2017 Category: Physics Source Type: research
Fundamentals of reactor physics with a view to the (possible) futures of nuclear energy
Publication date: Available online 18 October 2017 Source:Comptes Rendus Physique Author(s): Xavier Doligez, Sandra Bouneau, Sylvain David, Marc Ernoult, Abdoul-Aziz Zakari-Issoufou, Nicolas Thiollière, Adrien Bidaud, Olivier Méplan, Alexis Nuttin, Nicolas Capellan This paper present basic nuclear reactor physics that may help to understand next challenges that nuclear industry have to face in the future. The ones considered in this work are waste production and natural resources consumption. This paper shows that waste and resources are linked by the plutonium status that could be considered as the principal...
Source: Comptes Rendus Physique - October 18, 2017 Category: Physics Source Type: research
The Langevin equation
Publication date: Available online 18 October 2017 Source:Comptes Rendus Physique Author(s): Yves Pomeau, Jarosław Piasecki The existence of atoms has been long predicted by philosophers and scientists. The development of thermodynamics and of the statistical interpretation of its concepts at the end of the nineteenth century and in the early years of the twentieth century made it possible to bridge the gap of scales between the macroscopic world and the world of atoms. Einstein and Smoluchowski showed in 1905 and 1906 that the Brownian motion of particles of measurable size is a manifestation of the motion of atoms i...
Source: Comptes Rendus Physique - October 18, 2017 Category: Physics Source Type: research
Use of vegetal biomass for biofuels and bioenergy. Competition with the production of bioproducts and materials?
Publication date: Available online 16 October 2017 Source:Comptes Rendus Physique Author(s): Christine Chirat The total European bioeconomy represents 2.1 trillion euros turnover. It includes the food, feed and beverages sectors that are responsible for about half of the turnover. The bio-based industries – chemicals and plastics, pharmaceuticals, paper and paper products, forest-based industries, textile sector, biofuels, and bioenergy – contribute with 600 billion euros and 3.2 million employees. This paper will first give key figures for fossil fuel versus vegetal biomass stocks and production. The chemical compo...
Source: Comptes Rendus Physique - October 17, 2017 Category: Physics Source Type: research
Fran çois Massieu and the thermodynamic potentials
Publication date: Available online 13 October 2017 Source:Comptes Rendus Physique Author(s): Roger Balian The thermodynamic potentials have first been introduced in 1869 by François Massieu under the name of “fonctions caractéristiques” in two short articles published in the Comptes rendus de l'Académie des sciences. Motivated by applications to thermal engines, he showed how such a single function encompasses all properties of a fluid, linking its equation of state to its thermal properties. The conceptual interest of Massieu's functions was acknowledged many decades later. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - October 13, 2017 Category: Physics Source Type: research
Energy transitions after COP21 and 22
This article starts with a short analysis of the results of COP21 and COP22, the two “conferences of parties” where goals have been defined. Now, to define goals is one thing, but to reach these goals is another thing. In its second part, this article analyzes the energy transition that has been voted by France in 2015, and compares it to what is planned in other countries, especially in Germany. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - October 12, 2017 Category: Physics Source Type: research
On the universality (or not) of beautiful penguins
We present in this article how the presence of new particles can be probed by testing Lepton Universality in the decay of hadrons containing a b-quark. (Source: Comptes Rendus Physique)
Source: Comptes Rendus Physique - October 11, 2017 Category: Physics Source Type: research
“Smart buildings” integrated in “smart grids”: A key challenge for the energy transition by using physical models and optimization with a “human-in-the-loop” approach
Publication date: Available online 6 October 2017 Source:Comptes Rendus Physique Author(s): Frédéric Wurtz, Benoît Delinchant The big challenge for the 21th century is to decrease fossil energy use and to increase renewable energies in the framework of the climate constraint. The paper will show that smart buildings, connected to smart grids, can significantly contribute to this objective. Indeed, buildings are, on one side, the biggest consumers of energy in the electrical grid and could be among the greatest producers of renewable energy, especially thanks to the concept of energy positive buildings, and this by o...
Source: Comptes Rendus Physique - October 7, 2017 Category: Physics Source Type: research
