Colloquia

In his public talk, Prof. Narayan will summarize our knowledge of Black Holes in the universe. He will describe how Black Holes are discovered, how their properties are measured, and what the results mean. He will also discuss the many ways in which Black Holes influence their surroundings and the profound effect they have had on the evolution of the universe.

An astrophysical black hole is completely described with just two parameters: its mass and its dimensionless spin. A few dozen black holes have mass estimates, but until recently none had a reliable spin estimate. The first spins have now been measured for black holes in X-ray binaries. The talk will describe the method used to make these measurements and will discuss implications of the results obtained so far.

The Baryon Oscillation Spectroscopic Survey (BOSS) is a Stage III dark energy experiment on the Sloan Telescope. For the five years from 2009-2014, we are mapping 1.5 million galaxies at z<0.7. A simultaneous survey of 160,000 QSOs is mapping the hydrogen gas in absorption at redshifts 2 < z < 3. BOSS will provide the definitive measurement of the low redshift (z<0.7) BAO distance scale, and it will pioneer a powerful new method of measuring BAO at high redshift. BigBOSS is a proposed Stage IV dark energy experiment that will extend this map to 20 million galaxies over 14,000 deg² to z=1.7. I will describe this survey and its technical status.

En mi conferencia haré una introducción a la Física Cuántica y a continuación pasaré a discutir diferentes casos en los que los fenómenos cuánticos juegan un papel determinante en el trabajo de diferentes máquinas médicas. De hecho, los ejemplos que explicaré recorrerán la historia de la medicina moderna, la del siglo XX, desde el punto de vista de la terapia como de la inspección. Para todo ello tendré que echar mano, por ejemplo, del principio de incertidumbre de Heisenberg, del efecto túnel de la corriente eléctrica y del espín, de la resonancia atómica. Todo ello para explicar, entre otros casos, cómo se “ve” el corazón, cómo se detectan los pensamientos, porque el feto de la madre roba el oxígeno a la sangre de su madre para poder vivir.

El azar es un concepto fascinante que atrae el interés de diversas comunidades, desde filósofos a físicos y matemáticos. Por otro lado, los números aleatorios se han convertido en un recurso de gran utilidad práctica, puesto que son utilizados en, por ejemplo, aplicaciones criptográficas o la simulación de sistemas físicos y biológicos. Hasta ahora, cualquier propuesta para la generación de números aleatorios adolece de los siguientes problemas: (i) certificación: ¿cómo se puede probar que los números generados son aleatorios?, (ii) privacidad: ¿cómo se puede garantizar que los números aleatorios son aleatorios, en el sentido de impredecibles, a cualquier otro observador externo y (iii) device-independent: ¿cómo afectan las imperfecciones en los dispositivos al proceso de generación de azar? En la charla se presentará un nuevo formalismo para la generación de azar que resuelve estos tres problemas: por medio de las correlaciones no-locales de los estados entrelazados, es posible generar números cuya aleatoriedad es certificable, privada e independiente de los dispositivos.

In recent years, major changes were done at the IRAM Plateau de Bure interferometer and 30-meter telescope, in particular in the areas of receivers and back-ends. These enhancements increased in significant ways both the sensitivity and the efficiency of both IRAM facilities. I will present results obtained on high-z (2 < 6.4) sub-millimeter galaxies and quasars that illustrate the progress that has been made, emphasizing recent follow-up observations of sources that were uncovered in the Herschel surveys. The talk will end with a presentation of the future projects that are currently under discussion at IRAM, including the NOrthern Extended Millimeter Array (NOEMA), as well as the prospects offered by ALMA.

According to Quantum Chromodynamics, which is the well established theory of strong interactions, quark and gluons are forced to live inside hadrons because of the property of confinement. However, under extreme conditions of temperature and pressure, a new phase called quark-gluon plasma is possible, where quarks and gluons became basically free. In the last years it has been possible to study this phase experimentally by using new facilities called Heavy Ion Colliders like the RHIC (Brookhaven) or the LHC (CERN).

This lecture will address recent progress in modeling the emergence of cosmic structure at high redshifts. Also new insights gained from numerical simulations into the processes relevant for star formation are presented. Rapid magnetic field growth in galaxies and the important role of proto-stellar outflows regulating star formation up to pc scales are particularly highlighted.

In this talk I will summarise the events that led to the discovery of the first four pulsars, recount several instances where pulsars were almost discovered and reflect on what lessons we might draw from these stories.