3,922 research outputs found
Self-Referential Noise as a Fundamental Aspect of Reality
Noise is often used in the study of open systems, such as in classical
Brownian motion and in Quantum Dynamics, to model the influence of the
environment. However generalising results from G\"{o}del and Chaitin in
mathematics suggests that systems that are sufficiently rich that
self-referencing is possible contain intrinsic randomness. We argue that this
is relevant to modelling the universe, even though it is by definition a closed
system. We show how a three-dimensional process-space may arise, as a Prigogine
dissipative structure, from a non-geometric order-disorder model driven by,
what is termed, self-referential noise.Comment: 7 pages, Latex, 3 ps figures. Contribution to the 2nd International
Conference on Unsolved Problems of Noise, Adelaide 199
Non-singular spacetimes with a negative cosmological constant: III. Stationary solutions with matter fields
Generalising the results in arXiv:1612.00281, we construct
infinite-dimensional families of non-singular stationary space times, solutions
of Yang-Mills-Higgs-Einstein-Maxwell-Chern-Simons-dilaton-scalar field
equations with a negative cosmological constant. The families include an
infinite-dimensional family of solutions with the usual AdS conformal structure
at conformal infinity.Comment: 27 pages, v2: journal accepted versio
Large-scale fluctuation structures in plasma turbulence
The role of large-scale fluctuation structures in electrostatic drift-wave-type plasma turbulence is highlighted. In particular, well-defined laboratory experiments allow one to study the dynamics of drift wave mode structures as well as 'eddies' in drift wave turbulence. In the present paper we discuss the mutual relationships between observations made in linear magnetic geometry, purely toroidal geometry and magnetic confinement. The simplest structure, a saturated, nonlinear drift mode, is the starting point for a Ruelle-Takens-Newhouse transition route to chaos and weakly developed turbulence. Both spectral and phase space analysis are applied to characterize in detail the transition scenario, which is enforced due to an increased drive by the plasma equilibrium state. In addition to direct multi-probe observation, statistical approaches are most revealing for the systematic study of the spatiotemporal dynamics in fully developed drift wave turbulence. In particular, the propagation of large-scale 'eddy' structures is traced by conditional statistics methods. Finally, the control of drift wave turbulence by spatiotemporal synchronization is discussed
Thermal histories of the samples of two KOSI comet nucleus simulation experiments
Temperatures recorded during two KOSI comet nucleus simulation experiments strongly suggest that heat transport by vapor flow into the interior of the sample is very important. Two comet nucleus simulation experiments have been done by the KOSI team in a big space simulator. The thermal evolution of the sample during insolation and the results of simplified thermal evolution calculations are discussed. The observed thermal histories cannot be explained by a simple model with heat transferred by heat conduction at a constant conductivity, so a coupled heat and mass transfer problem was considered. The porous ice matrix was assumed to have a constant thermal conductivity and to be in thermal equilibrium with vapor in the pores, the internal pressure being the vapor pressure. The vapor was modelled as an ideal gas because, at the temperatures relevant to the problem, the mean free path length of the vapor molecules is large in comparison with the pore dimensions. The heat capacity at constant volume per unit mass of the two phase mixture was also assumed constant. The vapor was allowed to flow and transfer heat in response to an internal pressure gradient
- …