The Black Hole Stability Conjecture is one of the most important open problems in the field of General Relativity, and remains open in spite of the advances in the past half century.
To test Einstein’s theory and to establish the astrophysical relevance of the Kerr solution to the equations, it is essential to show that whether these are stable against small perturbations or not. That is, starting from a current state close to a Kerr solution, to find out if the state of evolution at any future time remains close to a Kerr solution or not. If not, these solutions will only exist in the mathematical realm and have no significance from a physical point of view. I came across this link where it is mentioned that the team of researchers at the Max Planck institute has "proved for the first time the linear stability of these solutions, the second last step towards proving this conjecture."
I found this to be an interesting topic of research and so I am looking for references/review articles to learn more about the conjecture and also the current status of research on the topic.