No. 28: Jul-Aug 1983
Imagine a million brilliant stars densely packed in a tight sphere by gravity. In the telescope these globular clusters are spectacular objects: a million points of light in disciplined motion around a center so closely packed with stars that they cannot all be resolved. Surely such an orderly assemblage of matter should be easy to model, given the laws of celestial mechanics and high-speed computers. No so! Both theory and computer models predict that a few stars may escape a globular cluster during its lifetime of several billion years, but that most will be drawn inevitably inward as the cluster collapses. However, observation, the final arbiter, reveals that globular clusters do not follow this scenario. Indeed, some clusters seem to have collapsed already and are again evolving in a sort of "reincarnated" state that our best theories refuse to predict.
(Lightman, Alan; "Misty Patches in the Sky," Science 83, 4:24, June 1983.)