Leopold Infeld Colloquium
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Origin of caves in limestone terrains. A process oriented modeling approach
Limestone rock is dissected by many narrow fractures, both horizontal and vertical, with aperture widths in the order of 0.1 mm. Water loaded with carbon dioxide penetrates into these fractures as a weak acid and can widen them by chemical dissolution of CaCO3. This process creates spectacular karst landscapes hosting caves and underground rivers. A model based on the hydrodynamics of flow in fracture systems and its coupling to dissolution of limestone is presented. From this model one can understand the processes by which caves and limestone aquifers originate. The model can be applied to a variety of geological and geochemical scenarios.
First, a short introduction into the chemistry of dissolution kinetics of calcite (CaCO3) in water containing carbon dioxide is given. As basic element of the model widening of a single plane parallel fracture is derived. Then the evolution of cave systems originating from local water inputs on a limestone plateau is presented. As a second building block of karst evolution it will be shown how an aquifer develops from evenly distributed input of rain water to the surface of a limestone plateau. In a third scenario the concept of mixing corrosion is applied to explain the origin of isolated caves without entrance and exit in Florida.Finally we use the model to discuss the risk to the operation of dam sites by evolution of karst conduits below the dam due to the high pressure by the impounded water. This can cause unbearable loss of water and endanger the structure of the dam.
Nobel 2016
Streszczenie:
The 2016 Nobel Prize in Physics was awarded to David J. Thouless, F. Duncan M. Haldane, and J. Michael Kosterlitz "for theoretical discoveries of topological phase transitions and topological phases of matter".
The Nobel Committee does not mention a specific discovery, but rather refers to a collection of groundbreaking results, which lay at the foundation of our current understanding of topological phases in quantum matter.
We aim at presenting a short account of the historical context and a pedagogical explanation of the original results associated with the names of Nobel 2016 Laureates. In our talk we will discuss:
1) phase transitions in two dimensions triggered by vortices,
2) the gapped phase of spin one chains and 3) the topological invariant underlining the physics of the quantum Hall effect.
We believe the intellectual achievements of this year's Laureates are breathtaking for their own sake, even without direct reference to applications. "It's very difficult to know whether something is useful or not, but one can know that it's exciting" -- as summarized by Haldane in the first Nobel interview.
Referat zostanie wygłoszony w ramach wspólnego posiedzenia konwersatoriów im. J. Pniewskiego i L. Infelda.
Zapraszamy!
Jan Kalinowski, Jerzy Kijowski, Czesław Radzewicz, Wojciech Satuła, Janusz Skalski
Bosonic Theory of Superconductivity
Historically, two paradigms competed to explain superconductivity (i) Bose Einstein Condensation (BEC) of weakly interacting Charge 2e pairs (Schafroth), and (ii) pairing instability of the Fermi liquid (BCS).
BCS theory was the unquestionable winner until the late 80's. BCS approximations however, have suffered major setbacks in the advent of high temperature, short coherence length superconductors, such as cuprates, pnictides, and granular superconducting films.
A third paradigm has offered itself for understanding some properties of unconventional superconductors: Strongly Interacting Lattice Bosons (LB). LB behave less like in BEC's or BCS theory, but (strangely) more like localized quantum spins. Their static correlations are very well understood by theories of quantum antiferromagnets. Their dynamics have only recently been explored. Near commensurate fillings, recent cold atom and thin films experiments have discovered the condensed matter version of the Higgs/ Amplitude mode. Conductivity of Lattice Bosons exhibit strange metallic properties, such as linear in temperature resistivity. LB also exhibit interesting vortex dynamics and Hall conductivity sign reversals.
Refs:
1. N. H. Lindner and A. Auerbach, Phys. Rev. B 81, 054512 (2010).
2. D. Podolsky, A. Auerbach, D. P. Arovas, Phys. Rev. B 84, 174522 (2011).
3. S. Gazit, D. Podolsky, A. Auerbach, Phys. Rev. Lett. 113, 240601 (2014).
4. D. Sherman et. al., Nature Physics 11, 188 (2015).