# How to make a black hole?

Many Physics discussions I have often conclude with:

Well you will then form a black hole...

My questions are:

• Is there a general recipe for making a black hole?

• If not, then can you list the families of black hole causes?

This means I can put a more rapid halt to many future Physics discussions.

• A general recipe for creating a black hole requires a general solution of the Einstein Field equations - but this has not yet been created. – user28355 Jan 12 '14 at 23:30

Whenever an amount of mass (or mass equivalent in energy) finds itself inside a volume smaller than the event-horizon for a Schwarzschild black hole of that mass ($R = \frac{Gm}{c^2}$), then you have the necessary and sufficient condition for a black hole. In fact, the black hole may form before the matter reaches this point, provided that it will reach it some time in the future.