Conveners
Relativity, Gravitation and Cosmology
- Hubert de Guise
Relativity, Gravitation and Cosmology
- Hubert de Guise
Relativity, Gravitation and Cosmology
- There are no conveners in this block
We describe a case of indeterminacy in general relativity for homogeneous and isotropic cosmologies for a class of dark energy fluids. The cosmologies are parametrized by an equation of state variable, with one instance giving the same solution as Norton’s mechanical dome. Our example goes beyond previously studied cases in that indeterminacy lies in the evolution of spacetime itself: the...
Recently, significant process has been made in the understanding of how two apparent horizons merge to become one during a black hole collision. Apparent horizons are examples of more general objects called marginally outer trapped surfaces (MOTS) and as an offshoot of the merger studies, we have learned that MOTS are much more common than had been previously realized. For example, apart from...
The Schwarzschild solution admits one parameter, the mass, which can be positive or negative. What is the meaning of the negative mass solution? Negative mass is an intriguing idea. Negative mass, to be physical, must satisfy the dominant energy condition. Indeed stable configurations can be found that correspond to bubbles of negative mass, however crucially, in a background energy density....
Exact solutions of the Einstein equations describing black holes in cosmological backgrounds exhibit time-dependent masses over Hubble times. We report tentative evidence for such a cosmological coupling obtained by studying populations of supermassive black holes in a sequence of red elliptical galaxies spanning 9 billion years. If black holes are non-singular, they typically have de Sitter...
Gravitational solitons are globally stationary, geodesically complete spacetimes with positive energy. These event-horizonless geometries do not exist in the electrovacuum by the classic Lichnerowicz Theorem. However, gravitational solitons exist when there are non-Abelian gauge fields in higher dimensions. In this talk, I will present a new class of supersymmetric asymptotically globally...
In general, black holes interact with
external matter and fields. A four-dimensional static black hole
within a static external axisymmetric gravitational field can be
described by a Weyl solution of the Einstein equations. These results
can be extended to higher dimensions using the generalized Weyl form.
Various studies have been devoted to investigate the properties of the
distorted...
The spacetime M in general relativity (GR) is curved. Parallel transportations of vectors in M depend on path. This leads to the fact that vectors distributed on different points in M can not be added up to get a sum vector unambiguously. Geometry does not allow talking about matter energy momentum distributed on (passing through) a finite or infinite spacelike (timelike) hypersurface, does...
