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Search Results: 1 - 10 of 529874 matches for " M. D. Maia "
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Cosmology and gravitation
Maia, M. D.;
Brazilian Journal of Physics , 2004, DOI: 10.1590/S0103-97332004000700022
Abstract: this is a brief summary with comments on selected contributions to the cosmology and gravitation section at the 24th brazilian meeting on particle and fields (enfpc xxiv), held at caxambu, from september 30 to october 4, 2003.
The extended ADS/CFT correspondence
Maia, M. D.;
Brazilian Journal of Physics , 2005, DOI: 10.1590/S0103-97332005000700037
Abstract: the correspondence between conformal covariant fields in minkowski's space-time and isometric fields in the five dimensional anti-desitter space-time is extended to a six-dimensional bulk space and its regular sub-manifolds, so as to include the analysis of evaporating schwarzschild's black holes without loss of quantum unitarity.
Spin and Isospin in Quaternion Quantum Mechanics
M. D. Maia
Physics , 1999,
Abstract: The algebraic consistency of spin and isospin at the level of an unbroken SU(2) gauge theory suggests the existence of an additional angular momentum besides the spin and isospin and also produces a full quaternionic spinor operator. The latter corresponds to a vector boson in space-time, interpreted as a SU(2) gauge field. The existence of quaternionic spinor fields implies in a quaternionic Hilbert space and its necessary mathematical analysis. It is shown how to obtain a unique representation of a quaternion function by a convergent positive power series.
Hypersurfaces of Five Dimensional Space-times
M. D. Maia
Physics , 1995,
Abstract: It is shown that a space-time hypersurface of a 5-dimensional Ricci-flat space-time has its energy momentum tensor algebrically related to its extrinsic curvature and to the Riemann curvature of the embedding space. It is also seen that the Einstein-Maxwell field does not arise naturally from this geometry, so that a Kaluza-Klein model based on it would require further assumptions.
About Time
M. D. Maia
Physics , 1996,
Abstract: The concept of time is discussed in the context of the canonical formulation of the gravitational field. Using a hypersurface orthogonal foliation, the arbitrariness of the lapse function is eliminated and the shift vector vanishes, allowing a consistent definition of time.
Applications of Nash's Theorem to Cosmology
M. D. Maia
Physics , 2008,
Abstract: The cosmological constant problem is seen as a symptom of the ambiguity of the Riemann curvature in general relativity. The solution of that ambiguity provided by Nash's theorem on gravitational perturbations along extra dimensions eliminate the direct comparison between the vacuum energy density and Einstein's cosmological constant, besides being compatible with the formation of structures and the accelerated expansion of the universe.
The Extended ADS/CFT Correspondence
M. D. Maia
Physics , 2006, DOI: 10.1590/S0103-97332005000700037
Abstract: The correspondence between conformal covariant fields in Minkowski's space-time and isometric fields in the five dimensional anti-deSitter space-time is extended to a six-dimensional bulk space and its regular sub-manifolds, so as to include the analysis of evaporating Schwarzschild's black holes without loss of quantum unitarity.
The Poincare Conjecture and the Cosmological Constant
M. D. Maia
Physics , 2011, DOI: 10.1142/S2010194511001280
Abstract: The concept of deformation of Riemannian geometry is reviewed, with applications to gravitation and cosmology. Starting with an analysis of the cosmological constant problem, it is shown that space-times are deformable in the sense of local change of shape. These deformations leave an observable signature in the space-time, characterized by a conserved tensor, associated with a tangent acceleration, defined by the extrinsic curvature of the space-time. In the applications to cosmology, we find that the accelerated expansion of the universe is the observable effect of the deformation, dispensing with the cosmological constant and its problems.
Information Storage in Black Holes
M. D. Maia
Physics , 2005, DOI: 10.1142/S0218271805007838
Abstract: The information loss paradox for Schwarzschild black holes is examined, using the ADS/CFT correspondence extended to the $M_6 (4,2)$ bulk. It is found that the only option compatible with the preservation of the quantum unitarity is when a regular remnant region of the black hole survives to the black hole evaporation process, where information can be stored and eventually retrieved.
Cosmology and Gravitation: Summary talk at the XXIV Brazilian Meeting on Particles and Fields
M. D. Maia
Physics , 2004,
Abstract: This is a brief summary with comments on selected contributions to the Cosmology and Gravitation section at the $24^{th}$ Brazilian Meeting on Particle and Fields (ENFPC XXIV), held at Caxambu, from September 30 to October 4, 2003.
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