73,854 research outputs found
Noncommutative gravity, a `no strings attached' quantum-classical duality, and the cosmological constant puzzle
There ought to exist a reformulation of quantum mechanics which does not
refer to an external classical spacetime manifold. Such a reformulation can be
achieved using the language of noncommutative differential geometry. A
consequence which follows is that the `weakly quantum, strongly gravitational'
dynamics of a relativistic particle whose mass is much greater than Planck mass
is dual to the `strongly quantum, weakly gravitational' dynamics of another
particle whose mass is much less than Planck mass. The masses of the two
particles are inversely related to each other, and the product of their masses
is equal to the square of Planck mass. This duality explains the observed value
of the cosmological constant, and also why this value is nonzero but extremely
small in Planck units.Comment: 7 pages. Second Prize in Gravity Research Foundation Essay
Competition, 2008. Two paragraphs added to original essay to enhance clarity.
To appear in Gen. Rel. Gra
A characterization of the central shell-focusing singularity in spherical gravitational collapse
We give a characterization of the central shell-focusing curvature
singularity that can form in the spherical gravitational collapse of a bounded
matter distribution obeying the dominant energy condition. This
characterization is based on the limiting behaviour of the mass function in the
neighbourhood of the singularity. Depending on the rate of growth of the mass
as a function of the area radius R, the singularity may be either covered or
naked. The singularity is naked if this growth rate is slower than R, covered
if it is faster than R, and either naked or covered if the growth rate is same
as R.Comment: 12 pages, Latex, significantly revised version, including change of
title. Revised version to appear in Classical and Quantum Gravit
Collective Oscillations of Strongly Correlated One-Dimensional Bosons on a Lattice
We study the dipole oscillations of strongly correlated 1D bosons, in the
hard-core limit, on a lattice, by an exact numerical approach. We show that far
from the regime where a Mott insulator appears in the system, damping is always
present and increases for larger initial displacements of the trap, causing
dramatic changes in the momentum distribution, . When a Mott insulator
sets in the middle of the trap, the center of mass barely moves after an
initial displacement, and remains very similar to the one in the ground
state. We also study changes introduced by the damping in the natural orbital
occupations, and the revival of the center of mass oscillations after long
times.Comment: 4 pages, 5 figures, published versio
Edge-Cloud Synergy: Unleashing the Potential of Parallel Processing for Big Data Analytics
If an edge-node orchestrator can partition Big Data tasks of variable computational complexity between the edge and cloud resources, major reductions in total task completion times can be achieved even at low Wide Area Network (WAN) speeds. The percentage time savings are greater with increasing task computational complexity and higher WAN speeds are required for low-complexity tasks. We demonstrate from numerical simulations that low-complexity tasks can benefit either by task partitioning between an edge node and multiple cloud servers. The orchestrator can also achieve greater time benefits by rerouting Big Data tasks directly to a single cloud resource if the balance of parameters (WAN speed and the ratio between edge and cloud processing speeds) is favourable
On kinetic energy stabilized superconductivity in cuprates
The possibility of kinetic energy driven superconductivity in cuprates as was
recently found in the model is discussed. We argue that the violation of
the virial theorem implied by this result is serious and means that the
description of superconductivity within the model is pathological.Comment: 3 pages, v2 includes additional reference
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