20,915 research outputs found
Down to earth relativity
The basic concepts of the special and general theories of relativity are described. Simple examples are given to illustrate the effect of relativity on measurements of time and frequency in the near-earth environment
Viking radio science data analysis and synthesis
Viking radio data analysis and synthesis was used for the following: (1) Solar System Model and Data Set; (2) Rotation of Mars; and (3) Solar System Constants and Tests of Relativity
Frobenius map for quintic threefolds
We calculate the matrix of the Frobenius map on the middle dimensional
cohomology of the one parameter family that is related by mirror symmetry to
the family of all quintic threefolds.Comment: 19 pages, discussion of -adic zeta values adde
Principles of very-long-baseline interferometry
The basic principles of very-long-baseline interferometry as related to its use in the determination of vector baselines, polar motion, and earth rotation are presented. Aspects relevant to geodetic applications that involve observations of extragalactic radio sources are covered. The instrumentation used in these observations and the basic observables and their simplest interpretation are described. Complications of the interpretation due to the various geophysical 'signals' and nongeophysical 'noise' that affect the observables are considered
BRST Reduction of the chiral Hecke Algebra
We explore the relationship between de Rham and Lie algebra cohomologies in
the finite dimensional and affine settings. As an application, we describe the
BRST reduction of the chiral Hecke algebra as a vertex super algebra.Comment: 35 page
Dark energy: a quantum fossil from the inflationary Universe?
The discovery of dark energy (DE) as the physical cause for the accelerated
expansion of the Universe is the most remarkable experimental finding of modern
cosmology. However, it leads to insurmountable theoretical difficulties from
the point of view of fundamental physics. Inflation, on the other hand,
constitutes another crucial ingredient, which seems necessary to solve other
cosmological conundrums and provides the primeval quantum seeds for structure
formation. One may wonder if there is any deep relationship between these two
paradigms. In this work, we suggest that the existence of the DE in the present
Universe could be linked to the quantum field theoretical mechanism that may
have triggered primordial inflation in the early Universe. This mechanism,
based on quantum conformal symmetry, induces a logarithmic,
asymptotically-free, running of the gravitational coupling. If this evolution
persists in the present Universe, and if matter is conserved, the general
covariance of Einstein's equations demands the existence of dynamical DE in the
form of a running cosmological term whose variation follows a power law of the
redshift.Comment: LaTeX, 14 pages, extended discussion. References added. Accepted in
J. Phys. A: Mathematical and Theoretica
The rotation of the planet Mercury
Rotation of planet Mercury from radar observation explained by solar gravitational torque on tidal deformation and equatorial plane asymmetr
Cosmology with running parameters
The experimental evidence that the equation of state (EOS) of the dark energy
(DE) could be evolving with time/redshift (including the possibility that it
might behave phantom-like near our time) suggests that there might be dynamical
DE fields that could explain this behavior. We propose, instead, that a
variable cosmological term (including perhaps a variable Newton's gravitational
coupling too) may account in a natural way for all these features.Comment: Talk given at TAUP 2005, Zaragoza, Spain, 10-14 Sep 200
- …