Search results for "General Relativity"
showing 10 items of 1057 documents
Thermodynamical Properties of Horizons
2002
We show, by using Regge calculus, that the entropy of any finite part of a Rindler horizon is, in the semi-classical limit, one quarter of the area of that part. We argue that this result implies that the entropy associated with any horizon of spacetime is, in semi-classical limit, one quarter of its area. As an example, we derive the Bekenstein-Hawking entropy law for the Schwarzschild black hole.
"Table 19" of "Search for heavy particles decaying into a top-quark pair in the fully hadronic final state in $pp$ collisions at $\sqrt{s} =13$ TeV w…
2020
Expected and observed upper limits on the cross-section times branching fraction of Kaluza-Klein graviton decaying into top-quark pair as a function of the graviton mass.
Einstein's Washington Manuscript on Unified Field Theory
2020
In this note, we point attention to and briefly discuss a curious manuscript of Einstein, composed in 1938 and entitled "Unified Field Theory," the only such writing, published or unpublished, carrying this title without any further specification. Apparently never intended for publication, the manuscript sheds light both on Einstein's modus operandi as well as on the public role of Einstein's later work on a unified field theory of gravitation and electromagnetism.
Václav Hlavatý on intuition in Riemannian space
2019
Abstract We present a historical commentary together with an English translation of a mathematical-philosophical paper by the Czech differential geometer and later proponent of a geometrized unified field theory Vaclav Hlavatý (1894–1969). The paper was published in 1924 at the height of interpretational debates about recent advancements in differential geometry triggered by the advent of Einstein's general theory of relativity. In the paper he argued against a naive generalization of analogical reasoning valid for curves and surfaces in three-dimensional Euclidean space to the case of higher-dimensional curved Riemannian spaces. Instead, he claimed, the only secure ground to arrive at resu…
Flat synchronizations in spherically symmetric space-times
2010
It is well known that the Schwarzschild space-time admits a spacelike slicing by flat instants and that the metric is regular at the horizon in the associated adapted coordinates (Painleve-Gullstrand metric form). We consider this type of flat slicings in an arbitrary spherically symmetric space-time. The condition ensuring its existence is analyzed, and then, we prove that, for any spherically symmetric flat slicing, the densities of the Weinberg momenta vanish. Finally, we deduce the Schwarzschild solution in the extended Painleve-Gullstrand-Lemaitre metric form by considering the coordinate decomposition of the vacuum Einstein equations with respect to a flat spacelike slicing.
Effect of the milling conditions on the degree of amorphization of selenium by milling in a planetary ball mill
2007
The effect of the milling parameters (rotation speed of the milling device and duration of milling) on the phase composition of the products of milling of fully crystalline selenium has been investigated. The milling was conducted using a planetary micromill and the phase composition of the milling products was determined by differential thermal analysis. It has been found that ball milling leads to the partial amorphization of the starting crystalline material. The content of amorphous phase in the milling products depends, in a rather complicated way, on the milling parameters. At the milling parameters adopted in the present study, the milling product was never fully amorphous. The compl…
Toward a scientific and personal biography of Tullio Levi-Civita (1873–1941)
2005
International audience; Tullio Levi-Civita was one of the most important Italian mathematicians in the early part of the 20th century, contributing significantly to a number of research fields in mathematics and physics. In addition, he was involved in the social and political life of his time and suffered severe political and racial persecution during the period of Fascism. He tried repeatedly and in several cases successfully to help colleagues and students who were victims of anti-Semitism in Italy and Germany. His scientific and private life is well documented in the letters and documents contained in his Archive. The authors' aim is to illustrate the events of his life by means of his …
Quantum search of spatial regions
2003
Can Grover's algorithm speed up search of a physical region - for example a 2-D grid of size sqrt(n) by sqrt(n)? The problem is that sqrt(n) time seems to be needed for each query, just to move amplitude across the grid. Here we show that this problem can be surmounted, refuting a claim to the contrary by Benioff. In particular, we show how to search a d-dimensional hypercube in time O(sqrt n) for d at least 3, or O((sqrt n)(log n)^(3/2)) for d=2. More generally, we introduce a model of quantum query complexity on graphs, motivated by fundamental physical limits on information storage, particularly the holographic principle from black hole thermodynamics. Our results in this model include a…
Cavity solitons in nondegenerate optical parametric oscillation
2000
Abstract We find analytically cavity solitons in nondegenerate optical parametric oscillators. These solitons are exact localised solutions of a pair of coupled parametrically driven Ginzburg–Landau equations describing the system for large pump detuning. We predict the existence of a Hopf bifurcation of the soliton resulting in a periodically pulsing localised structure. We give numerical evidence of the analytical results and address the problem of cavity soliton interaction.
Spanish Relativity Meeting (ERE 2014): almost 100 years after Einstein's revolution
2015
This volume presents the proceedings of the international scientific conference ''Spanish Relativity Meeting (ERE 2014): almost 100 years after Einstein's revolution''. The conference was devoted to discussing the current state-of-the-art of a wide variety of topics of research in the fields of Gravitation and General Relativity in the ''pre-centennial'' year of General Relativity. The name of the conference was chosen to highlight the importance of the upcoming one hundredth anniversary of Einstein's theory of General Relativity, officially established by the Internal Society on General Relativity and Gravitation in November 25th, 2015. In particular, the conference was organized along thr…