do black holes have a critical mass like uranium?

Answer 1

No. A critical mass of uranium is one where, on average, each fission even induces exactly one other fission elsewhere in the mass. Above critical mass, uranium is highly unstable and will blow itself apart from the exponentially increasing rate of fission in the material. Conversely, there is absolutely no mass above which black holes are unstable, and black holes do not undergo fission, thus black holes cannot be said to have a critical mass analogous to the critical mass of uranium.

Answer 2

Not quite the same thing, but yes; a star has to be something like 1.6 times the mass of the sun (absolute minimum) to become a black hole. So our sun can never be a black hole.

Answer 3

No, a black hollow can not and would not have a severe mass. the severe pass of gravity is what provides the phantasm of black holes possessing mass. Gravity flows continually by a black hollow and would not boost. there is not any severe mass ever built as much as a black hollow.

Answer 4

If black holes exist, maybe.