20 research outputs found
Nematic Structure of Space-Time and its Topological Defects in 5D Kaluza-Klein Theory
We show, that classical Kaluza-Klein theory possesses hidden nematic
dynamics. It appears as a consequence of 1+4-decomposition procedure, involving
4D observers 1-form \lambda. After extracting of boundary terms the, so called,
"effective matter" part of 5D geometrical action becomes proportional to square
of anholonomicity 3-form \lambda\wedge d\lambda. It can be interpreted as twist
nematic elastic energy, responsible for elastic reaction of 5D space-time on
presence of anholonomic 4D submanifold, defined by \lambda. We derive both 5D
covariant and 1+4 forms of 5D nematic equilibrium equations, consider simple
examples and discuss some 4D physical aspects of generic 5D nematic topological
defects.Comment: Latex-2e, 14 pages, 1 Fig., submitted to GR
Supermassive Black Holes as Giant Bose-Einstein Condensates
The Schwarzschild metric has a divergent energy density at the horizon, which
motivates a new approach to black holes. If matter is spread uniformly
throughout the interior of a supermassive black hole, with mass , it may arise from a Bose-Einstein condensate of densely
packed H-atoms. Within the Relativistic Theory of Gravitation with a positive
cosmological constant, a bosonic quantum field is coupled to the curvature
scalar. In the Bose-Einstein condensed groundstate an exact, selfconsistent
solution for the metric is presented. It is regular with a specific shape at
the origin. The redshift at the horizon is finite but large, . The binding energy remains as an additional parameter to
characterize the BH; alternatively, the mass observed at infinity can be any
fraction of the rest mass of its constituents.Comment: 6 pages, no figure
Quantum superposition principle and gravitational collapse: Scattering times for spherical shells
A quantum theory of spherically symmetric thin shells of null dust and their
gravitational field is studied. In Nucl. Phys. 603 (2001) 515 (hep-th/0007005),
it has been shown how superpositions of quantum states with different
geometries can lead to a solution of the singularity problem and black hole
information paradox: the shells bounce and re-expand and the evolution is
unitary. The corresponding scattering times will be defined in the present
paper. To this aim, a spherical mirror of radius R_m is introduced. The
classical formula for scattering times of the shell reflected from the mirror
is extended to quantum theory. The scattering times and their spreads are
calculated. They have a regular limit for R_m\to 0 and they reveal a resonance
at E_m = c^4R_m/2G. Except for the resonance, they are roughly of the order of
the time the light needs to cross the flat space distance between the observer
and the mirror. Some ideas are discussed of how the construction of the quantum
theory could be changed so that the scattering times become considerably
longer.Comment: 30 pages and 5 figures; the post-referee version: shortened and some
formulations improved; to be published in Physical Revie
”Utan en genomgripande demokratisering kommer vårt samhälle inte att kunna lösa sina problem” : Brev till det sovjetiska kommunistpartiets centralkommitté i mars 1970
Sociologisk Forsknings digitala arkiv</p