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The main idea of this passage is to get enough sleep. Lack of sleepness can reduce a person´s ability to concentrate.
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This temperature is on the order of billionths of a kelvin for black holes of stellar mass, making it essentially impossible to observe. Objects whose gravitational fields are too strong for light to escape were first considered in the 18th century by John Michell and Pierre-Simon Laplace.
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What exactly is the question?
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