https://phys.org/news/2018-07-method-nucleation.html > Crystal nucleation is an inherently stochastic process, and estimating each nucleation time requires growth models that work backward from the time at which the crystal grew to a detectable size. This temporal gap can range from several minutes to hours. > "It's like saying when someone became pregnant once the baby is outside," said Romain Grossier, an author of the paper at the French National Centre for Scientific Research and Aix-Marseille University. "We detect the moment of pregnancy."