Found 17 talks width keyword fundamental physics
There is a "Warped side" of our universe, consisting of objects and phenomena that are made solely or largely from warped spacetime. Examples are black holes, singularities (inside black holes and in the big bang), and cosmic strings. Numerical-relativity simulations are revolutionizing our understanding of what could exist on our universe's Warped Side; and gravitational-wave observations (LIGO, VIRGO, LISA, ...) will reveal what phenomena actually do exist on the Warped Side, and how they behave.
AbstractThe Atacama Cosmology Telescope (ACT) has been observing the southern sky in the millimeter range with an angular resolution at the arc-minute level. An analysis of 228 square degrees observed at 148 GHz along a stripe centered at declination -53 degrees reveals the presence of the Silk damping tail in the temperature angular power spectrum of the Cosmic Microwave Background (CMB). This decaying tail becomes truncated by a rising spectrum at scales corresponding to few arcmins (l ~ 3000) whose origin is compatible with a unclustered population of unresolved point sources and some residual anisotropy due to Compton scattering of CMB photons off free electrons (the Sunyaev-Zel'dovich effect). Comparisons with other observations and constraints on different components giving rise to this secondary spectrum are discussed.
En una parte preliminar se recordarán unos pocos hechos experimentales obtenidos durante las últimas décadas, con énfasis en fenómenos puramente cuánticos como el entrelazamiento y el teletransporte, y también algunos hechos matemáticos elementales, con énfasis en las matrices hermíticas y unitarias. En una segunda parte se presentará un modelo matemático de la noción de q-ordenador y de conceptos subordinados como puertas q-lógicas, q-computación y q-algoritmos programas, con énfasis en los ejemplos, incluyendo la q-transformada de Fourier y el q-algoritmo de Shor de factorización en tiempo polinómico de números enteros positivos. A continuación se sumarizará un enfoque axiomático de la mecánica cuántica y se usará para relacionar las q-nociones anteriores con sus posibles realizaciones físicas, con énfasis en algunos problemas abiertos y en posibles líneas de trabajo futuro. La base de este material es la tesis de máster de Juanjo Rué, "Un modelo matemático para la computación cuántica: fundamentos, algoritmos y aplicaciones" (julio de 2007), dirigida por Lluís Torner y el conferenciante.
AbstractThe standard model of cosmology -- the ``Lambda cold dark matter'' model -- is based on the idea that the dark matter is a collisionless elementary particle, probably a supersymmetric particle. This model (which mostly dates back to an early workshop in Santa Barbara in the 1980s) has been famously verified by observations of the cosmic microwave background radiation and the large-scale distribution of galaxies. However, the model has yet to be tested conclusively on the small scales appropriate to most astronomical objects, such as galaxies and clusters. I will review our current understanding of the distribution of dark matter on small scales which derives largely from large cosmological N-body simulations and I will discuss prospects for detecting dark matter, either through its gravitational effect on galaxies and clusters or, more directly, through gamma-ray annihilation radiation.
AbstractThe amount of baryons seen in the local Universe falls short by a factor2-5 if compared to the amount of detected baryons at intermediate (z~2)or high (z~1,100) redshift. This is the so called "missing baryon" problem in Cosmology. Hydrodynamical simulations of the large scale structure predict that most of those missing baryons should be in the form of ionized gas present in slightly overdense regions, at a temperature ranging from 10^5 to 10^7 K, conforming the "Warm Hot Intergalactic Medium" (WHIM). This WHIM would not form stars, and would not emit or absorb either in the IR, optical or UV. However, it should interact with the photons of the Cosmic Microwave Background (CMB) through two different channels: (i) Thompson scattering (where there is no energy exchange) and (ii) Compton scattering (where hot electrons transfer energy to the CMB photons, distorting their black body spectrum). I shall review the status of the search for missing baryons in the context of CMB observations and the currently most favored cosmological model. I shall also outline new methods and prospects for detecting this missing gas with upcoming CMB experiments and address the link between the cosmic baryon problem and the search for (so far undetected) bulk flows at scales of ~10 Mpc/h.
AbstractIn our now-standard picture for the growth of structure, dark matter halos are the basic unit of nonlinear structure in the present Universe. I will report results from simulations of galaxy-scale dark halos with more than an order of magnitude better mass resolution than any previously published work. Tests demonstrate detailed convergence for (sub)structures well below a millionth the mass of the final system. Even with such resolution the fraction of halo mass in bound subhalos does not rise above a few percent within the half-mass radius. I will also present a new simulation technique which allows structure in the dark matter distribution to be studied on very much smaller scales. This is required for accurate forecasts of the expected signal both in earth-bound experiments designed to detect dark matter directly, and in indirect detection experiments like GLAST which attempt to image dark matter annihilation radiation at gamma-ray wavelengths.
AbstractSince its discovery in 1964, the cosmic microwave background (CMB) has been one of the basic pillars of the cosmological model. However, it is only very recently that CMB observations have become one of the most powerful tools in modern cosmology, due to the increasing accuracy of the experiments measuring the CMB anisotropies. In this talk, I will present a brief historical perspective of the history of the CMB observations, since the discovery until nowadays, with special emphasis on the implications and the impact of those observations in cosmology. Experiments like COBE, Tenerife, WMAP or PLANCK will be described. The last part of my talk will be devoted to describe the future of this field, and in particular, will be focused on the possibility of the detection of primordial gravitational-waves.
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- Astronomical dating of ancient societies in the 2nd millennium BCEDr. Rita GautschyWednesday March 4, 2020 - 10:30 (Aula)
- The impossible Local Group of galaxiesDr. Pavel KroupaTuesday March 17, 2020 - 12:30 (Aula)