Science. 1977 Jul 1;197(4298):11-6. doi: 10.1126/science.197.4298.11.
I have argued, following Einstein and London, that Bose-Einstein statistics is important for understanding the behavior of superfluid (4)He, while Fermi-Dirac statistics is important for understanding that of (3)He. In order to understand qualitatively the general behavior of (3)He-(4)He mixtures at constant pressure, the interaction between the helium atoms cannot be neglected. A very simple model of (3)He-(4)He mixtures is then a binary mixture of two kinds of hard spheres that follow Bose-Einstein and Fermi-Dirac statistics, respectively. This model correctly predicts the most striking features of the phase diagrams of helium mixtures in the temperature-concentration plane. In particular, the Bose-Einstein statistics of (4)He is responsible for the occurrence of a phase separation of the mixture at low temperatures that starts at an unusual type of critical point, while the Fermi-Dirac statistics of (3)He leads to an incomplete phase separation near the absolute zero of temperature, which makes possible the successful operation of a powerful cooling device, the helium dilution refrigerator.
我曾追随爱因斯坦和伦敦的观点，认为玻色-爱因斯坦统计对于理解超流（4）He 的行为很重要，而费米-狄拉克统计对于理解（3）He 的行为则很重要。为了定性地理解（3）He-（4）He 混合物在恒压下的一般行为，氦原子之间的相互作用不能被忽略。那么（3）He-（4）He 混合物的一个非常简单的模型就是遵循玻色-爱因斯坦和费米-狄拉克统计的两种硬球的二元混合物。该模型正确地预测了氦混合物相图在温度-浓度平面上的最显著特征。特别是，（4）He 的玻色-爱因斯坦统计导致混合物在低温下发生分相，这种分相始于一种不寻常的临界点，而（3）He 的费米-狄拉克统计则导致在接近绝对零度的温度下发生不完全分相，这使得一种强大的冷却设备——氦稀释冰箱的成功运行成为可能。
