Archivi tag: general relativity

L’alba dell’astronomia gravitazionale

Forse non tutti sanno che la rivelazione sperimentale delle onde gravitazionali, avvenuta il 14 Settembre del 2015 e annunciata giovedì scorso 11 Febbraio 2016 in una conferenza stampa a Washington DC, è stata possibile grazie alla versione “avanzata” di LIGO (Advanced LIGO, a LIGO). Queste onde dello spazio, che allungano e accorciano la lunghezza dell’interferometro di una quantità incredibilmente piccola, hanno avuto origine da una violenta fusione (merger) di due buchi neri, di massa iniziale pari a una trentina di masse solari, così come riportato nell’articolo scientifico pubblicato su Physical Review Letters. Si tratta di un fenomeno accaduto in una galassia distante 1,3 miliardi di anni-luce e le “increspature” nello spaziotempo, per l’appunto le onde gravitazionali, sono arrivate qui sulla Terra qualche mese fa.
Continua a leggere L’alba dell’astronomia gravitazionale

Annunci

Hot Topics in General Relativity and Gravitation

In this centennial anniversary of General Relativity, we will hold a conference on Hot Topics in General Relativity and Gravitation with the motivation to emphasize the tremendous progresses that have been made in Astrophysics and in Cosmology since Einstein’s discovery of General Relativity (GR) in 1915. This international conference will be held at ICISE as part of the Rencontres du Vietnam. Continua a leggere Hot Topics in General Relativity and Gravitation

14th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories

The Fourteenth Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Gravitation, and Relativistic Field Theory will take place at the University of Rome Sapienza July 12 – 18, 2015, celebrating the 100th anniversary of the Einstein equations as well as the International Year of Light under the aegis of the United Nations. Continua a leggere 14th Marcel Grossmann Meeting on Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories

AdS/CFT, self-adjoint extension and the resolution of cosmological singularities

In the context of Einstein gravity coupled to matter satisfying fairly general energy conditions, cosmological singularities are unavoidable, as was proven by Hawking and Penrose many year ago. One of the hopes for superstring theory is that a solution to this problem may be found. Clearly, however, a non-perturbative formulation of string theory must be used. The AdS/CFT correspondence is a proposed definition of non-perturbative string theory (including gravity) in terms of a conformal field theory which does not involve gravity. It has been conjectured that the AdS/CFT correspondence can be used to resolve cosmological singularities. Initial work in this direction was done by different groups, including Craps-Hertog-Turok, Khoury-Ovrut-Steinhardt-Turok, Skenderis-McFadden, Silverstein-Horowitz and Das-Tridevi. Continua a leggere AdS/CFT, self-adjoint extension and the resolution of cosmological singularities

Drifting through the Cosmic Web

The Large Scale Structure of the Universe (LSS) was first discussed at the IAU Symposium No. 79 in 1977 in Tallinn. The title of the Symposium : “The Large Scale Structure of the Universe” , was the first official use of this term (J. Einasto). Since then, it has been of major interest in cosmology. This large scale pattern, emerged from the primordial density fluctuations of dark matter under the effect of gravity, is composed of nodes, filaments and walls surrounding large voids: it is a vast foam-like structure, aka the “cosmic web”, which provides constraints on the content of the universe and the nature of its components. Continua a leggere Drifting through the Cosmic Web

Extended Theories of Gravity

The cosmological constant and the physics behind dark energy that accelerates the expansion of the universe remain among the biggest mysteries in theoretical physics. An intriguing possibility is that these problems stem from extrapolating Einstein’s General relativity from the Solar system to the far infrared cosmological scales. In the other extreme, at the ultraviolet regime Einstein’s theory encounters notorious infinities resulting in spacetime singularities and obstacles to quantisation, which suggest new gravitational physics with possible repercussions to early universe physics. Continua a leggere Extended Theories of Gravity

Testing Gravity

A three day workshop on various ways of testing gravity (cosmological, astrophysical and terrestrial). This is a topical theme, in part because of the growing interest in modified gravity theories motivated by the unexplained nature of dark matter and dark energy, and in part by improving technologies that open opportunities for new types of tests. Continua a leggere Testing Gravity

Beyond ΛCDM

The aim of this conference is to survey the successes and shortcomings of the standard ΛCDM cosmological model, and to decide which theoretical and observational directions beyond ΛCDM will be the most fruitful over the coming decade. Continua a leggere Beyond ΛCDM