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Arxiv (Free subscription) | 1 hour ago
In this paper we present a model for 4 dimensional quantum gravity constructed using exotic smooth structure. We calculate the semi-classical expectation value of volume and correlation functions for several gravitational free-field actions and find that the results are similar, independent of the particular action that is chosen. These are first results of their kind in dimension 4, and represent...
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Arxiv (Free subscription) | 1 hour ago
We study the effect of a (3+1)-dimensional Chern-Simons electrodynamics on the equations governing the dynamics of magnetized plasma and fields. In this model, the Chern-Simons (CS) part consists of a dynamical pseudo-scalar field whose space-time derivatives couple with the electromagnetic field. We explore the CS corrections to the evolution equation for the magnetic field in a plasma with non-zero...
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Arxiv (Free subscription) | 1 hour ago
In this letter we discuss cosmological first order phase transitions with de Sitter bubbles nucleating on (inhomogeneous) matter backgrounds. The de Sitter bubble can be a toy model for an inflationary phase of universes like our own. Using the thin wall approximation and the Israel junction method we trace the classical evolution of the formed bubbles within a compound model. We first address homogeneous...
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Arxiv (Free subscription) | 1 hour ago
An extreme mass ratio inspiral consists of two parts: adiabatic inspiral and plunge. The plunge trajectory is quite universal (independent of initial conditions). We write an expression for its solution in closed-form and for the emitted universal waveform. In particular we extract an expression for the universal black-hole ringdown amplitudes, which reduces to solving certain ordinary (radial) differential...
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Arxiv (Free subscription) | 1 hour ago
In this talk, we discuss one of the dissipative processes which likely take place in the Early Universe. We assume that the matter filling the isotropic and homogeneous background is to be described by a relativistic viscous fluid characterized by an ultra-relativistic equation of state and finite bulk viscosity deduced from recent lattice QCD calculations and heavy-ion collisions experiments. We...
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Arxiv (Free subscription) | 1 hour ago
The present operation of the ground-based network of gravitational-wave laser interferometers in "enhanced" configuration brings the search for gravitational waves into a regime where detection is highly plausible. The development of techniques that allow us to discriminate a signal of astrophysical origin from instrumental artefacts in the interferometer data and to extract the full range...
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Arxiv (Free subscription) | 1 hour ago
Within the framework of classical field theory, the connection between the Dirac field as the field of matter and the spacetime metric is discussed. Polarization structure of the Dirac field is shown to be rich enough to determine the spacetime metric locally and to explain the emergence of observed matter as localized waveforms. The localization of the waveforms is explained as the result of the...
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Arxiv (Free subscription) | 11/20/2009
A new Lorentz gauge gravity model with R^2-type Lagrangian is proposed. In the absence of classical torsion the model admits a topological phase with an arbitrary metric. We analyze the equations of motion in constant curvature space-time background using the Lagrange formalism and demonstrate that the model possesses a minimal set of dynamic degrees of freedom for the torsion. Surprisingly, the number...
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Arxiv (Free subscription) | 11/20/2009
We consider new cosmological solutions which generalize the cosmological patch of the anti-deSitter space-time, allowing for fluids with equations of state such that $w\neq -1$. We use them to derive the associated full manifolds. We find that these solutions can all be embedded in flat five-dimensional space-time with $--+++$ signature, revealing deformed hyperboloids. The topology and causal-structure...
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Arxiv (Free subscription) | 11/20/2009
An exact solution is obtained for a massive scalar field conformally coupled with the curvature in a cosmological model with the scale factor $a(t) = a_0 / |t|$, corresponding to background matter with the equation of state $ p = - 5 \varepsilon /3 $. An expression for the number density of created particles is obtained, and its behavior is studies as the model approached the instant of a Big Rip....
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Arxiv (Free subscription) | 11/20/2009
This brief article sums up the possible imprints of loop quantum gravity effects on the cosmological microwave background. We focus on semi-classical terms and show that "Big Bounce" corrections, together with the "pre Big Bounce" state, could modify the observed spectrum.
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Arxiv (Free subscription) | 11/20/2009
Thermodynamical Behaviour of Inhomogeneous Universe with Varying $ \Lambda $ in Presence of Electromagnetic Field is obtained. $ F_{12} $ is the non-vanishing component of electromagnetic field tensor. To get a deterministic solution, it is assumed that the free gravitational field is Petrov type-II non-degenerate.The value of cosmological constant is found to be small and pasitive supported by recent...
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Arxiv (Free subscription) | 11/20/2009
We display some simple cosmological solutions of gravity theories with quadratic Ricci curvature terms added to the Einstein-Hilbert lagrangian which exhibit anisotropic inflation. The Hubble expansion rates are constant and unequal in three orthogonal directions. We describe the evolution of the simplest of these homogeneous and anisotropic cosmological models from its natural initial state and evaluate...
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Arxiv (Free subscription) | 11/20/2009
We review slightly a work by Horowitz and Maldecena solving the information loss problem for black holes by having inside the blackhole - near to the singularity - a boundary condition, as e.g the no boundary proposal by Hartle and Hawking. Here we propose to make this boundary condition come out of our imaginary action model (together with Masao Ninomiya). This model naturally begins effectively...
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Arxiv (Free subscription) | 11/20/2009
We study zoom-whirl behaviour of equal mass, non-spinning black hole binaries in full general relativity. The magnitude of the linear momentum of the initial data is fixed to that of a quasi-circular orbit, and its direction is varied. We find a global maximum in radiated energy for a configuration which completes roughly one orbit. The radiated energy in this case exceeds the value of a quasi-circular...
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aronaldox7 | 01/08/2009
Visit site for watching video of episode The Dumpling Paradox
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en - (not a member) - 09/29/2009
There’s only one legitimate place I’ve found to watch it, the rest seem like scams :-/ You can watch it over here though: http://www.vostuu.com/bigbangtheory.html
They...
en - (not a member) - 05/15/2009
thanks
en - (not a member) - 02/25/2009
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stephaxml | 12/20/2008
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csomboza | 12/11/2008
On The Big Bang Theory Season 2 Episode 11 , you will notice that Christmas is stressing out Leonard because his handsome colleague is now dating Penny and Leonard together with his friends are bothered by Sheldon’s obsession of giving presents for Christmas.
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