On Brane Solutions Related to Non-Singular Kac-Moody Algebras

A multidimensional gravitational model containing scalar fields and antisymmetric forms is considered. The manifold is chosen in the form $M = M_0 \times M_1 \times \cdots \times M_n$, where $M_i$ are Einstein spaces ($i \geq 1$). The sigma-model approach and exact solutions with intersecting composite branes (e.g. solutions with harmonic functions, $S$-brane and black brane ones) with intersection rules related to non-singular Kac-Moody (KM) algebras (e.g. hyperbolic ones) are reviewed. Some examples of solutions, e.g. corresponding to hyperbolic KM algebras: $H_2(q,q)$, $AE_3$, $HA_2^{(1)}$, $E_{10}$ and Lorentzian KM algebra $P_{10}$ are presented

Multitemporal generalization of Schwarzschild solution

The $n$-time generalization of Schwarzschild solution is considered. The equations of geodesics for the metric are integrated. The multitemporal analogues of Newton laws for the extended objects described by the solution are suggested. The scalar-vacuum generalization of the solution is also presented.Comment: 7 page

Models of G time variations in diverse dimensions

A review of different cosmological models in diverse dimensions leading to a relatively small time variation of the effective gravitational constant G is presented. Among them: 4-dimensional general scalar-tensor model, multidimensional vacuum model with two curved Einstein spaces, multidimensional model with multicomponent anisotropic "perfect fluid", S-brane model with scalar fields and two form field etc. It is shown that there exist different possible ways of explanation of relatively small time variation of the effective gravitational constant G compatible with present cosmological data (e.g. acceleration): 4-dimensional scalar-tensor theories or multidimensional cosmological models with different matter sources. The experimental bounds on G-dot may be satisfied ether in some restricted interval or for all allowed values of the synchronous time variable.Comment: 27 pages, Late

Multitemporal generalization of the Tangherlini solution

The n-time generalization of the Tangherlini solution [1] is considered. The equations of geodesics for the metric are integrated. For $n = 2$ it is shown that the naked singularity is absent only for two sets of parameters, corresponding to the trivial extensions of the Tangherlini solution. The motion of a relativistic particle in the multitemporal background is considered. This motion is governed by the gravitational mass tensor. Some generalizations of the solution, including the multitemporal analogue of the Myers-Perry charged black hole solution, are obtained.Comment: 14 pages. RGA-CSVR-005/9

Cosmological solutions in multidimensional model with multiple exponential potential

A family of cosmological solutions with $(n+1)$ Ricci-flat spaces in the theory with several scalar fields and multiple exponential potential is obtained when coupling vectors in exponents obey certain relations. Two subclasses of solutions with power-law and exponential behaviour of scale factors are singled out. It is proved that power-law solutions may take place only when coupling vectors are linearly independent and exponential dependence occurs for linearly dependent set of coupling vectors. A subfamily of solutions with accelerated expansion is singled out. A generalized isotropization behaviours of certain classes of general solutions are found. In quantum case exact solutions to Wheeler-DeWitt equation are obtained and special "ground state" wave functions are considered.Comment: 22 pages, 1 figur

Reusable interorbital tugs of megawatt class: problems and prospects

The possibilities of creating solar reusable megawatt-class interorbital tugs are analyzing. A comparison of solar and nuclear power plants is given, and the advantages of using solar systems are justified. On the basis of a comparative analysis of analogues, such as solar sails, solar reflectors for illumination from Earth's orbit, solar panels of space power plants, the advantages of using frameless centrifugal solar panels in comparison with frame analogues are justified. It is indicated that the design and development, as well as the production and technological reserve and test base are sufficient for the creation of a solar power plant in the Russian Federation. The authors point out the prospect of using oxygen-hydrogen fuels obtained by electrolysis of water in space, which greatly increase the speed of transport operations, and the need to create electro-magnetic accelerators for launching from Earth with large cargo flows. The design evaluation of the parameters of centrifugal solar panels with a capacity of 1 and 5 MW is given. The necessary funding for the work was estimated

Space Project SEE for Measuring G and its Possible Spatial and Time Variations

La misión llamada SEE (Satellite Energy Exchange) fue designada para realizar mediciones extremadamente precisas sobre gravitación fundamental mediante la observación de la perturbación orbital a las órbitas contraidas de cuerpos orbitantes de pruebas en un medio gravitacional de femto-g hasta atto-g. La misión SEE usará la dinámica novedosa y original de cuerpos en prueba. La gravitación no está presente en las teorías de unificación. El objeto amplio de la misión SEE consiste en fortalecer el desarrollo de la teoría gravitatoria y la teoría de unificación llevando a cabo pruebas gravitacionales sensitivas capaces de discernir sobre la viabilidad de las diferentes teorías alternativas. La misión SEE introducirá y realizará nueva tegnología para la creación de un medio cercano-zero, de control criogénico pasivo de temperatura, de capacidad pasiva de resguardo de estación, de medición de distancias sin contacto y de resolución sub-micrónica, todo lo cual promete tener aplicaciones en amplia variedad de naves espaciales