DEATH STAR

摘要

Nobody has ever seen a black hole. Yet, despite this lack of direct evidence, most scientists believe that a massive star at the end of its life can implode to form an object so dense that nothing―not even light―can escape. They may be about to change their minds, however. Two researchers in the US are pointing out that physicists have swept some "humiliating" problems with black holes under the carpet. By confronting these problems, they say, they have found an alternative fate for a collapsing star. Emil Mottola of the Los Alamos National Laboratory in New Mexico and Pawel Mazur of the University of South Carolina in Columbia think it might turn into an exotic bubble of superdense matter, an object they call a gravastar. According to Mottola and Mazur, gravastars are cold, dense shells supported by a springy, weird space inside. They'd look like black holes, lit only by the material raining down onto them from outside. In fact, they seem to fit all the observational evidence for the existence of black holes.