相关论文: Some Consequences of Fuzzy Spacetime
A review is made of recent efforts to find relations between the commutation relations which define a noncommutative geometry and the gravitational field which remains as a shadow in the commutative limit.
Fundamental astronomical questions on the composition of the universe, the abundance of Earth-like planets, and the cause of the brightest explosions in the universe are being attacked by robotic telescopes costing billions of dollars and…
In next five years, dramatic progress is anticipated for the AGN studies, as we have two important missions to observe celestial sources in the high energy regime: GLAST and Suzaku. In this talk, I will summarize recent highlights in…
A U(1) gauge theory turns, on physically motivated models of Quantum Spacetime, into a U($\infty$) gauge theory, hence free classical electrodynamics is no longer free and neutral fields may have electromagnetic interactions. We discuss the…
Inflation can act as a space-time microscope for Planck or string scale effects, leaving potentially observable traces in the primordial perturbation spectrum. I discuss two frameworks that were used recently to study this phenomenon:…
We investigate the consequences of space-time being curved on space-based quantum communication protocols. We analyze tasks that require either the exchange of single photons in a certain entanglement distribution protocol or beams of light…
Driven by increasingly complete observational knowledge of systems of satellite galaxies, mutual spatial alignments and relations in velocities among satellites belonging to a common host have become a productive field of research. Numerous…
We discuss the cosmological consequences of QCD phase transition(s) on the early universe. We argue that our recent knowledge about the transport properties of quark-gluon plasma (QGP) should throw additional lights on the actual time…
The possibility of a Newtonian gravitomagnetic field is considered here with its immediate and far-reaching implications for the interpretation of 2004 LAGEOS experimental results confirming the general relativistic prediction of…
We consider the propagation of galactic cosmic rays under assumption that the interstellar medium is a fractal one. An anomalous diffusion equation in terms of fractional derivatives is used to describe of cosmic ray propagation. The…
In May 2008 the long awaited NASA Satellite, GLAST was launched, which will study cosmic gamma rays. In August 2008, it is expected that the CERN's Large Hadron Collidor (LHC) will finally become operationized. This is found to unwield…
The discovery of X-ray, optical and radio afterglows of GRBs provides an important tool for understanding these sources. Most current models envisage GRB as arising in a cataclysmic stellar event leading to a relativistically expanding…
Many candidate fundamental theories contain scalar fields that can acquire spacetime-varying expectation values in a cosmological context. Such scalars typically obey Lorentz-violating effective dispersion relations. We illustrate this fact…
Quantum gravitational effects may induce stochastic fluctuations in the structure of space-time, to produce a characteristic foamy structure. It has been known for some time now that these fluctuations may have observable consequencies for…
We perform a numerical comparison between the fuzzy dark matter model and the cold dark matter model, focusing on formation of satellite galaxy planes around massive galaxies. Such galactic dynamics with controlled initial subhalo…
We reexamine non-Einsteinian effects observable in the orbital motion of low-orbit artificial Earth satellites. The motivations for doing so are twofold: (i) recent theoretical studies suggest that the correct theory of gravity might…
We study the effects of the galactic magnetic field on the ultra high energy cosmic ray propagation. We show that the deflections of the cosmic ray trajectories can have many important implications such as (de)magnification of the cosmic…
The existence of a fundamental length (or fundamental time) has been conjecture in many contexts. Here one discusses some consequences of a fundamental constant of this type, which emerges as a consequence of deformation-stability…
A fundamental spacetime scale in the universe leads to noncommutative spacetime and thence to a modified energy - momentum dispersion relation or equivalently to a modification of Lorentz symmetry as shown by the author and others. This…
We consider the feasibility of using the Galileo Navigation Satellite System to constrain possible extensions or modifications to General Relativity, by assessing the impact of the related additions to the Newtonian potential and comparing…