Archivi tag: 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

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Symmetries and Phases in the Universe

Cosmology is a broad interdisciplinary research discipline involving different fields of physics. The main goal of the Excellence Cluster Universe is to face the fundamental challenges of modern cosmology by bridging the gap between the astrophysics and the particle/nuclear physics communities. Continua a leggere Symmetries and Phases in the Universe

Iberian Cosmology Meeting 2015

This series of meetings is aimed at encouraging the interaction and collaboration between researchers working in Cosmology and related areas (Gravitation, Particle Physics and Astronomy) in Portugal and Spain.  Continua a leggere Iberian Cosmology Meeting 2015

Gravitation, Astrophysics, and Cosmology

Research on Gravitation, Astrophysics, and Cosmology in Argentina and Brazil has reached a substantial degree of development. We believe, however, that the interaction between groups of both countries working in these areas is still not strong enough to undertake long-term, successful joint research programs. It was with the goal of stimulating collaboration that we started the series of Argentinian-Brazilian Meetings on Gravitation, Astrophysics, and Cosmology.

The first meeting was held in Foz do Iguaçu, Brazil, in October 2011, with the attendance of 76 researchers and students from Argentina and Brazil. The conference consisted in a number of invited review talks encompassing a wide and balanced range of topics, that offered a complete panorama of the research lines of both communities. The meeting closed with a round-table discussion. Participants could also present their work as posters.

The organization of the second meeting of the series aims at strengthening the links between both communities, and fully involving a larger number of researchers and students in the discussions. The scheme of the conference will change to include contributed talks, together with a few invited presentations by well-known specialists on topics of particular relevance. We as well intend to encourage the involvement of researchers from Brazil and Argentina in the Cherenkov Telescope Array Consortium (CTA, http://www.cta-observatory.org/), and to explore the applications in the fields of Astrophysics and Cosmology of the binational project Long Latin American Millimeter Array (LLAMA, http://www.iar.unlp.edu.ar/llama-web/).

Testing the string theory with astronomy

Il “Sacro Graal” della fisica potrebbe venire alla luce. E’ oggi quello che un gruppo di fisici del Department of Physics, Astronomy and Geosciences presso la Towson University (TU) sperano di aver trovato dopo quasi mezzo secolo di ricerche: verificare sperimentalmente una delle teorie più elusive e più complicate da capire, la teoria delle stringhe, osservando il moto dei pianeti, della Luna e degli asteroidi in una sorta di reminiscenza di uno dei più famosi test realizzati da Galileo sulla caduta dei gravi dalla Torre di Pisa.

Scientists have joked about how string theory is promising…and always will be promising, for lack of being able to test it”, says James Overduin, professor in Towson’s Department of Physics, Astronomy and Geosciences and lead author on a paper about the test TU scientists are developing. The paper was presented at the 223rd Meeting of the American Astronomical Society in Washington.

String theory posits an explanation for the connection between all the forces in the Universe. If it sounds overly broad, it is; string theory is nicknamed “the theory of everything.”

Scientific theories need tests in order to be truly valid, and string theory hasn’t been testable because the energy level and size to see its effects are just too big. “What we have identified is a straightforward method to detect cracks in general relativity that could be explained by string theory, with almost no strings attached”, Overduin explains. For most people, the understanding of string theory goes about as far as CBS’s “The Big Bang Theory” can convey it. The very basic explanation of the complex concept is that all matter and energy in the Universe is made of one-dimensional strings, a quintillion times smaller than the extremely tiny hydrogen atom. That means the strings are too small to detect indirectly, and finding signs of them in an instrument like a particle accelerator would require millions of times more energy than what was used to uncover, for example, the Higgs boson, a particle pivotal to the explanation and further proof of particle theory. The Higgs boson was posited in the 1960s, around the same time as string theory’s introduction; the boson’s identification was announced in 2012. The TU team’s string theory test borrows from Galilean and Newtonian laws of gravity. History holds that Galileo tested rates of acceleration by simultaneously dropping balls of two different weights off the Tower of Pisa to demonstrate that, despite the weight difference, they would hit the ground at the same time. Newton later found that Jupiter and its moons, in their orbits, “fall” at the same rate of acceleration toward the Sun. Much later, Einstein developed the theory of relativity when he recognized that gravity pulls all masses with precisely the same amount of strength, regardless of size.

Overduin and his team use those understandings for their test because string theory posits violations of Einstein’s relativity. It asserts that there are other fields that couple with objects differently, depending on the objects’ composition. That makes them accelerate differently, even within the same gravitational field.

But why does it matter? According to Overduin, the answer is nothing short of revolution. “Every time physicists have succeeded in unifying two different branches of physics, society has been transformed”, Overduin says. The Scientific Revolution was born of Newton’s unification of physics and astronomy. The Industrial Revolution, steam engines leading to train and boat transportation, began after physicists unified mechanics and heat. Electrification came when James Clerk Maxwell unified electricity and magnetism. Einstein’s relativity ushered in the Atomic Age, and then the Information Age, when relativity entered the quantum mechanics. That leaves two parts of physics still unconnected: gravitation and everything else. Physicists believe unifying them, as a test of string theory could do, would spark yet another revolution. But for all this time, they couldn’t do it. Towson University scientists might.

TU: TU scientists may spark revolution with string theory test

arXiv: Expanded solar-system limits on violations of the equivalence principle

The “Dark Side of the Universe”

The meeting is in the Series of the DSU workshops previeusly held in Seoul (2005), Madrid (2006), Minnesota (2007), Cairo (2008), Melbourne (2009), Leon (2010), Beijing (2011) and Buzios, Rio de Janeiro (2012). For more info, see DSU HomePage. Observations imply that about 95% of the Universe’s energy lies in a “dark sector”. In front of a 5% of the energy of the Universe made by ordinary matter (i.e. by atoms and molecules) there is a misterious sector comprised of dark matter, a form of non-luminous matter of unknown composition, and of dark energy, a sort of an antigravity field whose origin and composition is also unknown Dark matter makes up 23% of the Universe and it possibly consists of a “sea” of exotic particles that interact very weakly with ordinary matter. They are never been detected in laboratory or elsewhere but are thought to encompass any luminous structure of the Universe. Dark energy, makes 73% of the energy of the Universe, is responsible for a mysterious force that is speeding up its expansion. Then to understand the Dark Side of the Universe is the outstanding fundamental problems in physics and cosmology, and it may possibly lead to teories beyond the standard models of particle physics and Big Bang Cosmology. In the past few years all this has prompted many phenomenal strings of connections between Particle Physics, Astrophysics and Cosmology. The aim of the meeting is to bring together experts from all around the world to discuss, at a momentous time, the latest advances in the theoretical, phenomenological and experimental aspects of the issue and to draw a new cosmology/Elementary particles paradigm able to overcome the present and future observational challenges.

Topics of the workshop:

  • Observational Cosmology. Planck results.
  • Dark Energy: origin, evolution and observational properties.
  • Observational properties of Galaxies.
  • Dark Matter in Galaxies, Groups and Clusters.
  • Old and New Dark Matter candidates.
  • Direct and Indirect Dark Matter searches.
  • Simulations in Galaxy/Cluster Formation.
  • Abandoning the LCDM Universe paradigm?
  • Ultra high energy cosmic rays.
  • Modifying Newton-Einstein Theory of Gravity?

Neutron Stars: Nuclear Physics, Gravitational Waves and Astronomy

A basic cornerstone of modern physics is the quest to describe quantitatively the properties of nuclear matter. Neutron stars are unique beacons in this journey, as their interiors expose matter to extreme regimes of density, temperature and energy, not accessible to terrestrial experiments. Moreover, the intense gravitational fields in these astrophysical compact objects, particularly in binaries, could give rise to potentially detectable signals in the next generation of gravitational wave detectors. The astronomical observation of compact objects thus provides a unique insight into the properties of nuclear matter in extreme regimes. Better and more reliable theoretical tools and a more thorough modeling are required to interpret observations. Finally, one needs to connect present and future observation to the underlying microphysics associated to the strong interaction.

This international workshop aims at bringing together a number of historically disjoint research communities: nuclear physicists, astrophysicists and general relativists. Taking advantage of a multi-disciplinary environment, we plan to identify key issues in compact star physics and to develop strategies to make the most of the new generation of astronomical observatories, gravitational wave detectors and nuclear experiments.

Karl Schwarzschild Meeting On Gravitation

The first Karl Schwarzschild Meeting (KSM) on Gravitational Physics will be held in Frankfurt am Main, Germany on 22-26 July, 2013. The foundational spirit of the meeting can be summarized as: “by acknowledging the past we open a route to the future”. The five-day meeting will bring together both working specialists in the field of black hole physics and rising young researchers to foster new conversations and collaborations.