Can black holes become stars again?

It is impossible for a black hole to become a star again, because simply absorbing matter and energy cannot eliminate the singularity of time and space.

Whether the temperature of a black hole is higher than its surroundings depends on its mass. Not all black holes are hotter than their surroundings (cosmic microwave background). For example, a black hole with a mass close to the sun has a lower temperature than its surrounding environment, and it absorbs more energy from the cosmic microwave background radiation than it emits.

Extended data:

A black hole cannot be observed directly, but its existence and mass can be indirectly known, and its influence on other things can be observed. The information about the existence of a black hole can be obtained by the "edge information" of X-rays and γ-rays released by the friction caused by the acceleration brought by the gravity of the black hole before the object is sucked in. Inferring the existence of black holes can also be obtained by indirectly observing the orbits of stars or interstellar clouds, and the position and mass can also be obtained.

On April19th, Beijing time, 2 1, the first black hole photo appeared. The black hole is located in the center of a huge elliptical galaxy M87 in Virgo, 55 million light years away from the Earth, and its mass is about 6.5 billion times that of the sun.

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