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Horizon (general Relativity)
{{dabconcept A horizon is a wikt:boundary, boundary in spacetime satisfying prescribed conditions. There are several types of horizons that play a role in Albert Einstein's theory of general relativity: * Absolute horizon, a boundary in spacetime in general relativity inside of which events cannot affect an external observer * Event horizon, a boundary in spacetime beyond which events cannot affect the observer, thus referring to a black hole's boundary and the boundary of an expanding universe * Apparent horizon, a surface defined in general relativity * Cauchy horizon, a surface found in the study of Cauchy problems * Cosmological horizon, a limit of observability * Killing horizon, a null surface on which there is a Wilhelm Killing, Killing vector field * Particle horizon, the maximum distance from which particles can have travelled to an observer in the age of the universe General relativity ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Boundary
Boundary or Boundaries may refer to: * Border, in political geography Entertainment *Boundaries (2016 film), ''Boundaries'' (2016 film), a 2016 Canadian film *Boundaries (2018 film), ''Boundaries'' (2018 film), a 2018 American-Canadian road trip film *Boundary (cricket), the edge of the playing field, or a scoring shot where the ball is hit to or beyond that point *Boundary (sports), the sidelines of a field Mathematics and physics *Boundary (topology), the closure minus the interior of a subset of a topological space; an edge in the topology of manifolds, as in the case of a 'manifold with boundary' *Boundary (graph theory), the vertices of edges between a subgraph and the rest of a graph *Boundary (chain complex), its abstractization in chain complexes *Boundary value problem, a differential equation together with a set of additional restraints called the boundary conditions *Boundary (thermodynamic), Boundary (thermodynamics), the edge of a thermodynamic system across which he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |