Black holes keep ‘burping up’ stars they destroyed years earlier, and astronomers don’t know why::Years after ripping stars to shreds, 24 black holes suddenly flared up with radio waves in inexplicable ‘burping’ bouts. Half of all star-killing black holes may experience the same.
It’s an oversimplification, but something with the mass of say, a human, will be crushed into a very very very very tiny space. A much smaller space than 0.1mm radius, which would hold Earth’s moon’s mass of 7.342×10^22 kg.
Yes… And something with the mass of the universe will crush into a significantly larger (yet comparatively tiny) volume of space… Thus, a black hole is basically the maximum density we can currently comprehend and theorize.