It is no good getting furious if you get stuck. What I do is keep thinking about the problem but work on something else. Sometimes it is years before I see the way forward. In the case of information loss and black holes, it was 29 years.
“I learned a long time ago that some people would rather die than forgive. It's a strange truth, but forgiveness is a painful and difficult process. It's not something that happens overnight. It's an evolution of the heart.”