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I keep hearing about big bang, but there are no white holes and no black hole has been observed exploding. So is there a point in which a black hole reaches critical mass?

Qmechanic
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Muze
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    I'm voting to close this question as off-topic because it shows no effort at own research. – Gert Aug 02 '16 at 02:33
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    Your question implies that you think the Big Bang was like an exploding black hole so just for the record let's make clear that the spacetime geometry of the Big Bang is completely different to the spacetime geometry of a black hole. For more on this see Did the Big Bang happen at a point? – John Rennie Aug 02 '16 at 06:00

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Black hole evaporation depends on its mass. As the mass shrinks, the evaporation will be faster. In its last stage, this will be more like an explosion.

It is a significantly different thing as the supernovas or the nuclear bombs explode. In their case, there is a minimal mass which is required for this process to happen.

Now the problem is that the size of the currently known black holes are all at least 3-4 solar mass. They would require around $10^{50}$ years to evaporate. Compare this to the age of the Universe ($13.7\cdot 10^9$ years).

Remark: nobody ever could measure even the Hawking-radiation. It is very far from any experimental possibility. And it is not very strong even theoretically.

Google for Hawking radiation, black hole evaporation, the wikipedia has a lot of nice, high school-level formulas for it.

peterh
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