A fantastically compact object, predicted by the theory of general relativity, whose gravity is so powerful that not even light can escape from it. A black hole forms when matter collapses to infinite
density, producing a singularity of infinite curvature in the fabric of space-time. Each black hole is surrounded by an event horizon, at which the escape velocity is the speed of light. The Schwarzschild radius for the Sun is about 3 km and for the Earth about 1 cm. There is observational evidence for black holes on a remarkable range of scales in the Universe: stellar black hole, intermediate-mass black hole, primordial black hole, mini black hole, supermassive black hole, Schwarzschild black hole, Kerr black hole.
A fantastically compact object, predicted by the theory of general relativity, whose gravity is so powerful that not even light can escape from it. A black hole forms when matter collapses to infinite
density, producing a singularity of infinite curvature in the fabric of space-time. Each black hole is surrounded by an event horizon, at which the escape velocity is the speed of light. The Schwarzschild radius for the Sun is about 3 km and for the Earth about 1 cm. There is observational evidence for black holes on a remarkable range of scales in the Universe: stellar black hole, intermediate-mass black hole, primordial black hole, mini black hole, supermassive black hole, Schwarzschild black hole, Kerr black hole.
1.Thin, new ice on freshwater or saltwater, appearing dark in color because of its transparency, which is a result of its columnar grain structure. On lakes, black ice is commonly overlain by white ic
e formed from refrozen snow or slush. 2.A mariner's term for a dreaded form of icing sometimes sufficiently heavy to capsize a small ship. 3.A popular alternative for glaze. A thin sheet of ice, relatively dark in appearance, may form when light rain or drizzle falls on a road surface that is at a temperature below 0C. It may also be formed when supercooled fog droplets are intercepted by buildings, fences, and vegetation.
1. Slang reference to patchy ice on roadways or other transportation surfaces that cannot easily be seen. 2. In hydrologic terms, transparent ice formed in rivers and lakes.
(1) Thin ice on a fresh or salt water body which appears dark in colour because of its transparency. (2) A mariner's term for a dreaded form of icing sometimes sufficiently heavy to capsize a small sh
ip.