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skippy1729
Are there any exact solutions known for a black hole in a universe which is NOT asymptotically flat?
So you think radially rising light has some kind of apogee?Sam Gralla said:An event horizon is defined as the boundary of the past of future null infinity, but there's no such thing as null infinity if the spacetime is not AF. (Intuitively, a black hole is a region of spacetime from which nothing can escape--but if there's no infinity, what does "escape" even mean?)
A black hole metric is a mathematical representation of the spacetime geometry around a black hole. It describes how the curvature of space and time is affected by the presence of a black hole and how objects move in this curved spacetime.
The metric of a black hole is calculated using Einstein's field equations, which relate the curvature of spacetime to the distribution of matter and energy within it. The specific calculation depends on the mass, spin, and charge of the black hole.
The most commonly studied black hole metrics are the Schwarzschild metric, which describes a non-rotating, uncharged black hole, the Kerr metric, which describes a rotating black hole, and the Reissner-Nordström metric, which describes a charged black hole. There are also more complex metrics that take into account multiple black holes, or the effects of gravitational waves.
Black hole metrics can tell us about the properties of black holes, such as their mass, spin, and charge. They can also give us insights into how objects move around black holes and how spacetime is affected by their presence. Additionally, black hole metrics have been used to make predictions about observable phenomena, such as gravitational lensing and the emission of Hawking radiation.
Black hole metrics play a crucial role in our understanding of the universe as they provide a way to study and predict the behavior of these extreme objects. They also help us to test and refine our understanding of gravity and the laws of physics in the extreme conditions near black holes. Furthermore, black hole metrics are important in the study of cosmology, as black holes are thought to play a significant role in the evolution of galaxies and the large-scale structure of the universe.