This article also gives a readable background and summary of the problem and theory: https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12173137

This article also gives a readable background and summary of the problem and theory: https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&objectid=12173137 https://www.nzherald.co.nz/world/news/article.cfm?c_id=2&obj...