Between the theories of big-bang cosmology and the theory of stellar structure and theory, there is a gap still rarely understood: how do the galaxies form? 然而在大爆炸宇宙模型和恒星演化理论之间存在一个人们了解甚少的领域:就是由大量恒星组成而又作为宇宙基本单元的星系是如何形成和演化的?
(cosmology) the theory that the universe originated sometime between 10 billion and 20 billion years ago from the cataclysmic explosion of a small volume of matter at extremely high density and temperature