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Mammoth Cave National Park

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  Mammoth Cave National Park is an American national park in central Kentucky , encompassing portions of Mammoth Cave, the longest cave system known in the world . Since the 1972 unification of Mammoth Cave with the even-longer system under Flint Ridge to the north, the official name of the system has been the Mammoth–Flint Ridge Cave System. The park was established as a national park on July 1, 1941, a World Heritage Site on October 27, 1981, and an international Biosphere Reserve on September 26, 1990. The park's 52,830 acres (21,380 ha) are located primarily in Edmonson County , with small areas extending eastward into Hart and Barren counties. The Green River runs through the park, with a tributary called the Nolin River feeding into the Green just inside the park. Mammoth Cave is the world's longest known cave system with more than 400 miles (640 km) of surveyed passageways, [3] [4] which is nearly twice as long as the second-longest cave system, Mexico &
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Black Hole

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  https://en.wikipedia.org/wiki/Black_hole Matthew Ginnow, Matt Ginnow  A black hole is a region of spacetime where gravity is so strong that nothing—no particles or even electromagnetic radiation such as light —can escape from it. [1] The theory of general relativity predicts that a sufficiently compact mass can deform spacetime to form a black hole. [2] [3] The boundary of the region from which no escape is possible is called the event horizon . Although the event horizon has an enormous effect on the fate and circumstances of an object crossing it, according to general relativity it has no locally detectable features. [4] In many ways, a black hole acts like an ideal black body , as it reflects no light. [5] [6] Moreover, quantum field theory in curved spacetime predicts that event horizons emit Hawking radiation , with the same spectrum as a black body of a temperature inversely proportional to its mass. This temperature is on the order of billionths of a k
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