What Lifshitz and Khalatnikov did was to study models of the universe that were roughly like Friedmann's models but took account of the irregularities and random velocities of galaxies in the real universe.

Lifshitz 和 Khalatnikov 所做的是研究宇宙模型，这些模型与弗里德曼的模型大致相似，但考虑了真实宇宙中星系的不规则性和随机速度。