Doing Physics in the Cores of Globular Star Clusters

质量约为太阳八倍的恒星以白矮星(WD)的形式结束生命。这些恒星已经完成了它们的核进化，将它们的核心氢转化为氦，然后转化为碳和氧。然后恒星收缩，直到其电子的压力(量子力学电子简并压力)变得足够高，使恒星达到引力(想要收缩)和压力(想要膨胀)之间的平衡。这一过程的终点是一颗质量约为太阳一半、半径约为地球半径的恒星。到目前为止，WD已经耗尽了其潜在的核燃料来源，所以它只是将存储的热能辐射到太空中，并随着时间的推移缓慢而可预测地冷却-WDS是很好的时钟。这为物理实验室提供了在地球上无法复制的条件；温度约为1亿度，密度约为水的100万倍，并有一个精确的启动时钟。有了这个几乎是独一无二的实验室，就有可能进行奇异的物理实验。

Stars up to about eight times the mass of our Sun end their lives as white dwarf stars (WDs). These stars have completed their nuclear evolution, converting their core of hydrogen into helium and then into carbon and oxygen. The star then contracts until the pressure of its electrons (the quantum mechanical electron degeneracy pressure) becomes high enough for the star to reach a balance between gravity (that wants to contract it) and pressure (that wants to expand it). The end point of this process is a star about half the mass of the Sun and about the radius of the Earth. The WD has depleted its potential source of nuclear fuel by this time, so it simply radiates its stored thermal energy out into space and cools slowly and predictably with time - WDS are good clocks. This provides a physical laboratory with conditions that cannot be reproduced on Earth; temperature about 100 million degrees, density of order of 1 million times that of water and a precise clock to boot. With this almost unique laboratory, it is possible to carry out exotic physical experiments.