Because the shell lies well inside its Schwarzschild radius once it reaches $r=2E$, an <Schwarzschild event horizon>[event horizon] forms and the final exterior is a <Schwarzschild spacetime>[black hole] of mass $E$. In the ideal instantaneous-shell model the collapse ends at a spacetime singularity.

Solution

Past exam of the mathematics course of the University of Cambridge / 2021 / ii / Paper 3 / 37C / c / iii / Solution

 Solution (source code)