2,936 research outputs found
On searches for gravitational waves from mini creation event by laser interferometric detectors
As an alternative view to the standard big bang cosmology the quasi-steady
state cosmology(QSSC) argues that the universe was not created in a single
great explosion; it neither had a beginning nor will it ever come to an end.
The creation of new matter in the universe is a regular feature occurring
through finite explosive events. Each creation event is called a mini-bang or,
a mini creation event(MCE). Gravitational waves are expected to be generated
due to any anisotropy present in this process of creation. Mini creation event
ejecting matter in two oppositely directed jets is thus a source of
gravitational waves which can in principle be detected by laser interferometric
detectors. In the present work we consider the gravitational waveforms
propagated by linear jets and then estimate the response of laser
interferometric detectors like LIGO and LISA
The cosmological BCS mechanism and the Big Bang Singularity
We provide a novel mechanism that resolves the Big Bang Singularity present
in FRW space-times without the need for ghost fields. Building on the fact that
a four-fermion interaction arises in General Relativity when fermions are
covariantly coupled, we show that at early times the decrease in scale factor
enhances the correlation between pairs of fermions. This enhancement leads to a
BCS-like condensation of the fermions and opens a gap dynamically driving the
Hubble parameter to zero and results in a non-singular bounce, at least in
some special cases.Comment: replaced to match the journal versio
Fluid dynamic studies on scattering aerosol and its generation for application as tracer particles in supersonic flow measurements utilizing laser Doppler velocimeter
An experimental study on the particle-fluid interactions of scattering aerosols was performed using monodisperse aerosols of different particle sizes for the application of laser Doppler velocimeters in subsonic turbulence measurements. Particle response was measured by subjecting the particles to an acoustically excited oscillatory fluid velocity field and by comparing the ratio of particle velocity amplitude to the fluid velocity amplitude as a function of particle size and the frequency of oscillation. Particle velocity was measured by using a differential laser Doppler velocimeter. The test aerosols were fairly monodisperse with a mean diameter that could be controlled over the size range from 0.1 to 1.0 micron. Experimental results on the generation of a fairly monodisperse aerosol of solid particles and liquid droplets and on the aerosol response in the frequency range 100 Hz to 100 kHz are presented. It is indicated that a unit density spherical scatterer of 0.3 micron-diameter would be an optimum choice as tracer particles for subsonic air turbulence measurements
Novel self-assembled morphologies from isotropic interactions
We present results from particle simulations with isotropic medium range
interactions in two dimensions. At low temperature novel types of aggregated
structures appear. We show that these structures can be explained by
spontaneous symmetry breaking in analytic solutions to an adaptation of the
spherical spin model. We predict the critical particle number where the
symmetry breaking occurs and show that the resulting phase diagram agrees well
with results from particle simulations.Comment: 4 pages, 4 figure
Vacuum friction in rotating particles
We study the frictional torque acting on particles rotating in empty space.
At zero temperature, vacuum friction transforms mechanical energy into light
emission and produces particle heating. However, particle cooling relative to
the environment occurs at finite temperatures and low rotation velocities.
Radiation emission is boosted and its spectrum significantly departed from a
hot-body emission profile as the velocity increases. Stopping times ranging
from hours to billions of years are predicted for materials, particle sizes,
and temperatures accessible to experiment. Implications for the behavior of
cosmic dust are discussed.Comment: 4 figures, 10 pages, includes paper and supplementary information in
the appendi
B polarization of the CMB from Faraday rotation
We study the effect of Faraday rotation due to a homogeneous magnetic field
on the polarization of the cosmic microwave background (CMB). Scalar
fluctuations give rise only to parity-even E-type polarization of the CMB.
However in the presence of a magnetic field, a non-vanishing parity-odd B-type
polarization component is produced through Faraday rotation. We derive the
exact solution for the E and B modes generated by scalar perturbations
including the Faraday rotation effect of a uniform magnetic field, and evaluate
their cross-correlations with temperature anisotropies. We compute the angular
autocorrelation function of the B-modes in the limit that the Faraday rotation
is small. We find that primordial magnetic fields of present strength around
G rotate E-modes into B-modes with amplitude comparable to those
due to the weak gravitational lensing effect at frequencies around
GHz. The strength of B-modes produced by Faraday rotation scales as
. We evaluate also the depolarizing effect of Faraday rotation upon
the cross correlation between temperature anisotropy and E-type polarization.Comment: 11 pages, 4 figures. Minor changes to match the published versio
Come to Daddy? Claiming Chris Cunningham for British Art Cinema
Twenty years after he came to prominence via a series of provocative, ground-breaking music videos, Chris Cunningham remains a troubling, elusive figure within British visual culture. His output – which includes short films, advertisements, art gallery commissions, installations, music production and a touring multi-screen live performance – is relatively slim, and his seemingly slow work rate (and tendency to leave projects uncompleted or unreleased) has been a frustration for fans and commentators, particularly those who hoped he would channel his interests and talents into a full-length ‘feature’ film project. There has been a diverse critical response to his musical sensitivity, his associations with UK electronica culture – and the Warp label in particular – his working relationship with Aphex Twin, his importance within the history of the pop video and his deployment of transgressive, suggestive imagery involving mutated, traumatised or robotic bodies. However, this article makes a claim for placing Cunningham within discourses of British art cinema. It proposes that the many contradictions that define and animate Cunningham's work – narrative versus abstraction, political engagement versus surrealism, sincerity versus provocation, commerce versus experimentation, art versus craft, a ‘British’ sensibility versus a transnational one – are also those that typify a particular terrain of British film culture that falls awkwardly between populism and experimentalism
QSSC re-examined for the newly discovered SNe Ia
We examine the possible consistency of the quasi-steady state model with the
newly discovered SNe Ia. The model assumes the existence of metallic dust
ejected from the SNe explosions, which extinguishes light travelling over long
distances. We find that the model shows a reasonable fit to the data, which
improves if one takes account of the weak gravitational lensing effect of the
SNe which have been observed on the brighter side.Comment: 13 pages including 2 figures; accepted in Int. J. Mod. Phys.
A study of the angular size-redshift relation for models in which decays as the energy density
By modifying the Chen and Wu ansatz, we have investigated some Friedmann
models in which varies as . In order to test the consistency of
the models with observations, we study the angular size - redshift relation for
256 ultracompact radio sources selected by Jackson and Dodgson. The angular
sizes of these sources were determined by using very long-baseline
interferometry in order to avoid any evolutionary effects. The models fit the
data very well and require an accelerating universe with a positive
cosmological constant. Open, flat and closed models are almost equally
probable, though the open model provides a comparatively better fit to the
data. The models are found to have intermediate density and imply the existence
of dark matter, though not as much as in the canonical Einstein-de Sitter
model.Comment: LaTex, 15 pages including 2 figures (Revised version appeared in CQG
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