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Macroscopic Diffusive Transport in a Microscopically Integrable Hamiltonian System Imprimir
Bojan Zunkovic
Departamento de Física, FCFM
Universidad de Chile

Viernes 20 de diciembre, 16:00hrs
Av Blanco Encalada 2008, 3er piso
Sala de Seminarios

Derivation of irreversible macroscopic transport laws, for example Fourier’s heat law, Ohm’s law or Fick’s law, from reversible, deterministic, microscopic equations of motion is one of the central questions of statistical physics which remains largely unsolved even today. Recently, few examples of spin-diffusion at high temperature in completely integrable but strongly interacting quantum spin/particle chains have appeared, suggesting that complete integrability might not exclude the possibility of macroscopically diffusive dynamics. We shall show that diffusive transport is possible also in classical integrable systems. We shall discuss the insight gained from a seemingly unrelated problem, namely the task of finding the non-equilibrium steady state (NESS) in open quantum systems. In this regard we shall relate the quantum inverse scattering method approach to find NESS to quasi local conservation laws and the "improved" Mazur statement.

Observación: Charla en Inglés.
 

Seminarios Anteriores

Effects of inhomogeneities on apparent cosmological observables: "fake" evolving dark energy Imprimir
Expositor: Antonio Enea Romano
Instituto de Física
Universidad de Antioquia
Colombia

Viernes 13 de diciembre, 16:00hrs
Av Blanco Encalada 2008, 3er piso
Sala de Seminarios

Using the exact Lemaitre-Bondi-Tolman solution with a non-vanishing cosmological constant Λ, we investigate how the presence of a local spherically-symmetric inhomogeneity can affect apparent cosmological observables, such as the deceleration parameter or the effective equation of state of dark energy (DE), derived from the luminosity distance under the assumption that the real space-time is exactly homogeneous and isotropic. The presence of a local underdensity is found to produce apparent phantom behavior of DE, while a locally overdense region leads to apparent quintessence behavior. We consider relatively small large scale inhomogeneities which today are not linear and could be seeded by primordial curvature perturbations compatible with CMB bounds. Our study shows how observations in an inhomogeneous ΛCDM universe with initial conditions compatible with the inflationary beginning, if interpreted under the wrong assumption of homogeneity, can lead to the wrong conclusion about the presence of "fake" evolving dark energy instead of Λ. 

Observación: Charla en Inglés.
 
From elastocapillarity to delamination and cracks Imprimir
Expositor: José Bico
Laboratoire PMMH
ESPCI, Paris
France

Viernes 6 de diciembre, 16:00hrs
Av Blanco Encalada 2008, 3er piso
Sala de Seminarios

Washing our hair teaches us how capillary forces may be strong enough to deform slender structures. Such elasto-capillary interactions are usually considered as a limitation for the development of micro-devices. Conversely, capillary forces may be regarded as a useful tool for micro-fabrication. We shall consider how the concepts derived for elasto-capillary systems can be generalized to other surface interactions such as adhesion or fracture. In particular we shall describe recent experiments involving an original crack mode.

Observación: Charla en inglés
 
Estructuras en camas granulares fluidizadas cuasi-unidimensionales Imprimir
Expositor: Claudio Falcon
Departamento de Física, FCFM
Universidad de Chile

Viernes 29 de noviembre, 16:00hrs
Av Blanco Encalada 2008, 3er piso
Sala de Seminarios

En esta charla discutiremos algunos resultados experimentales, numéricos y teóricos recientes sobre el proceso de formación de estructuras subarmónicas en camas fludizadas unidimensionales vía un flujo de aire periódico, la dinámica de que esta granular muestra a tiempos largos y la estructura de las fluctuaciones superficiales que presenta. Nos centraremos en particular en la formación de patrones estacionarios subarmónicos, que pueden ser entendidos teóricamente usando una descripción universal vía ecuaciones de amplitud para el modo crítico, y a la formación de estructuras localizadas llamados kinks, que presentan una dinámica de evolución a saltos, muy similar ala de una partícula browniana en un potencial periódico.

Observación: Charla en castellano
 
Higgs in the sky? Imprimir
Expositora: Marieke Postma
NIKHEF
Amsterdam
Holanda

Viernes 22 de noviembre, 16:00hrs
Av Blanco Encalada 2008, 3er piso
Sala de Seminarios

In July 2012 a new boson, likely the standard model Higgs boson, was announced by the ATLAS and CMS collaborations at the Large Hadron Collider (LHC) at CERN. In March 2013 the Planck satellite team released its data on the cosmic microwave background (CMB) -the afterglow of the big bang- which revealed an 'almost perfect universe'. In this talk I will discuss the possibility that these seemingly disparate experiments are in fact related. That it is the Higgs boson that is responsible for the observed fluctuations in the CMB, and consequently, for all structure we see in our universe. If true, we can learn more about particle physics by looking at the sky, and vice versa, learn about cosmology by smashing protons together.

Observación: Charla en inglés
 
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