Colloquium - 2013/2014

Colloquium, année 2013 - 2014

Tous les jeudis à 13h30 en salle 236, 29 rue d’Ulm Paris.

Economic & Financial Crises A physicist’s viewpoint (video)

Jean-Philippe Bouchaud (Capital Fund Management, Paris, France) - 22 mai 2014. « The Economic Crisis is a Crisis for Economic Theory » recently wrote Alan Kirman. The theory in question posits that agents are rational and that markets are (...) | ↦ Lire la suite

Why do we see it that way ? Testing physics-based theories of visual computation

William Bialek (Princeton University, USA City University of New York) - 15 mai 2014. Helmholtz understood that perception is inference. What we "see" is not the raw data collected by the array of detectors in our eyes, but an interpretation. (...) | ↦ Lire la suite

Sampling the movement phenospace - Towards a biophysics of behavior in the wiggling of C. elegans

Greg Stephens (Vrije Universiteit, Amsterdam, Netherlands) - Jeudi 10 avril. We apply a low-dimensional yet complete representation of body shape (eigenworms) to construct a principled parameterization of the 2D movement behavior of the (...) | ↦ Lire la suite

La physique surprise - Renouveler les exemples pour la vulgarisation et l’enseignement

Jean-Michel Courty et Edouard Kierlik (LKB et LPTMC) - Jeudi 3 avril. Dans la chronique « Idées de Physique » que nous tenons dans la revue Pour la Science, nous introduisons les lois de la physique et la démarche du physicien grâce à des sujets (...) | ↦ Lire la suite

Conformal Symmetry of Critical Fluctuations in 3D

Slava Rychkov (Université Paris 6, Ecole Normale Supérieure, CERN) - Jeudi 27 mars. Renormalization group (RG) and Conformal Field Theory (CFT) are two complementary approaches to the theory of critical phenomena. The RG explains the underlying (...) | ↦ Lire la suite

Fast and slow quenches across second order phase transitions - The density of topological defects (video)

Leticia Cugliandolo (Professeur, Université Paris Pierre et Marie Curie) - jeudi 20 mars 2014. When a dissipative macroscopic system is driven through a second order phase transition (a quench) it undergoes an ordering process, usually called (...) | ↦ Lire la suite

Thermodynamics of strongly correlated gases

Frédéric Chevy (Ecole Normale Supérieure, Paris) - Jeudi 13 mars. The understanding of the properties of strongly correlated quantum systems is one of the most challenging open problems in modern physics, since it is relevant to fields as (...) | ↦ Lire la suite

Tracking nonequilibrium physics in a living cell

Frédéric van Wijland (Université Paris Diderot, France) - Jeudi 6 mars. Living cells are chemically driven systems that produce, on top of thermal noise, a wealth of nonequilibrium fluctuations. These fluctuations can be accessed, and quantified, (...) | ↦ Lire la suite

Physics of Cancer - The role of angiogenesis and tumor vascularization (video)

Heiko Rieger (Saarland University, Saarbrucken, Germany) - Jeudi 13 février. Growing tumors remodel the vascular network by generating new blood vessels (angiogensis) as well as by co-opting already existing vessels from the arterio-venous (...) | ↦ Lire la suite

Black hole accretion and cosmic evolution - The case of our Galaxy’s own Sgr A* (video)

Sera Markoff (University of Amsterdam, Netherlands) - Jeudi 6 février. Sgr A* is the weakest accreting black hole we have ever observed, yet it is not a particularly unique object. We know that the majority of galaxies harbor nuclear black holes (...) | ↦ Lire la suite

Quantum limit of heat flow across an elementary transport channel (video)

Frédéric Pierre (Laboratoire de Photonique et de Nanostructures, Marcoussis, France) - Jeudi 30 janvier. At small scale, such that quantum coherence is preserved, the flow of particles across a conductor can be decomposed into elementary modes (...) | ↦ Lire la suite

Gas Phase Carbon Balance in C-Rich Evolved Stars (video)

Jose Cernicharo (Centro de Astrobologia, Madrid, Spain) - Jeudi 23 janvier. Radio observations are the most powerful tool to derive the abundance of polar carbon chain radicals. However, key species as C2H2, CH4, C2H4, and even larger (...) | ↦ Lire la suite

Polymers, Message Passing, and London Underground Routes (video)

K. Y. Michael Wong (The Hong Kong University of Science and Technology, China) - Jeudi 16 janvier. Route planning is important in many applications, ranging from subway traffic to Internet communication. The challenge is to optimize the path (...) | ↦ Lire la suite

Quantum memories with cold atomic ensembles (video)

Elisabeth Giacobino (Laboratoire Kastler Brossel) - Jeudi 9 janvier. For quantum information, critical resources are quantum memories, which enable the storage of quantum data. They will also allow the distribution of entanglement at large (...) | ↦ Lire la suite

Imaging magnetic fields at the nanoscale with a single spin in diamond (Remise du prix Branly 2013) (video)

Vincent Jacques (Laboratoire de Photonique Quantique et Moléculaire, ENS Cachan Laboratoire Aimé Cotton, Orsay) - Jeudi 12 décembre. The ability to map magnetic field distributions with high sensitivity and nanoscale resolution is of crucial (...) | ↦ Lire la suite

Analysis of fluid systems by optimization techniques (video)

Peter Schmid (Ecole Polytechnique, Palaiseau) - Jeudi 5 décembre. When analyzing fluid systems, we are commonly interested in information about the amplification of internal disturbances (flow stability), the response to external excitations (...) | ↦ Lire la suite

When the environment drives the system quantum Some surprises in quantum dissipation (video)

Gert Ingold (Universität Augsburg, Germany) - Jeudi 28 novembre. Generally, it is thought that the coupling to an environment tends to suppress the quantum behavior of a system. However, there exist situations where the system owes its (...) | ↦ Lire la suite

Mesoscopic Superconductivity what Do We Learn from Single Atom Contacts ? (video)

Hugues Pothier (SPEC, CEA Saclay) - Jeudi 21 novembre. Superconductors are characterized by a dissipationless current. Since the work of Josephson 50 years ago, it is known that a supercurrent can even flow through tunnel junctions between (...) | ↦ Lire la suite

Statistical physics of compressed sensing (video)

Marc Mezard (Ecole Normale Supérieure, Paris LPTMS, Université Paris Sud, CNRS) - Jeudi 14 novembre. Compressed sensing is a major new topic in information theory. Starting from the observation that interesting signals can be compressed, and thus (...) | ↦ Lire la suite

Some new results on the history of ancient mathematical geography (video)

Lucio Russo (University of Rome Tor Vergata, Italy) - Jeudi 7 novembre. Claudius Ptolemy, in the second century C.E., ascribes to the earth a size that was significantly smaller than that determined by Eratosthenes four centuries earlier. (...) | ↦ Lire la suite

Casimir Energies and Forces An Accelerating Subject (video)

Kimball Milton University of Oklahoma, USA - Jeudi 17 octobre. There has been an acceleration of interest in quantum vacuum forces, including Casimir-Polder and Casimir forces. Dramatic improvements in theory and experiment have taken place (...) | ↦ Lire la suite

Remise du prix des 3 physiciens How masses have been generated in the early Universe

Jean Iliopoulos Ecole Normale Supérieure, Paris - Jeudi 10 octobre. The recent discovery of a new particle at CERN made headlines in world media. The discovery itself was a triumph of technology and ingenuity, but the excitement was mainly (...) | ↦ Lire la suite

Turbulence and condensate 2/2 -Cours du département- (video)

Gregory Falkovich Weizmann Institute for Science, Israel - Jeudi 3 octobre. This second lecture is in principle independent of the first one. It is devoted to interaction of turbulence and the mode coherent across the system which we call (...) | ↦ Lire la suite

Emerging and broken symmetries in turbulence 1/2 -Cours du département- (video)

Gregory Falkovich Weizmann Institute for Science, Israel - Jeudi 26 septembre. I start from a brief introduction to turbulence as far-from-equilibrium state of any system with many degrees of freedom. Examples will be taken not only from (...) | ↦ Lire la suite