black holes are caused when a star doesnt have any hydrogen left to burn and convert into helium.
It starts burning the helium then and expands to grow into a super/hyper giant. As it continues to grow, it cools. And eventually the rate at which it can support its own mass can no longer be balanced, and gravity wins. Gravity squeezes the star down to a incredibly small size. Seconds later it explodes in a violent explosing called a super nova. If the start is large enough it will implode into the size of an atom, where at, its gravity becomes infinite. Within the black hole, nothing can escape, not even light...
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