black hole

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black hole Postulated end-product of the total gravitational collapse of a massive star into itself following exhaustion of its nuclear fuel; the matter inside is crushed to unimaginably high density. It is an empty region of distorted space-time that acts as a centre of gravitational attraction; matter is drawn towards it, and once inside nothing can escape. Its boundary (the event horizon) is a demarcation line, rather than a material surface. Black holes can have an immense range of sizes. Since no light or other radiation can escape from black holes, they are extremely difficult to detect. Not all black holes result from stellar collapse. During the Big Bang, some regions of space might have become so compressed that they formed so-called primordial black holes Such black holes would not be completely black, because radiation could still ‘tunnel out’ of the event horizon at a steady rate, leading to the evaporation of the hole. Primordial black holes could therefore be very hot.

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