Science. 1967 Mar 17;155(3768):1369-76. doi: 10.1126/science.155.3768.1369.
Two recent observations appear to have provided critical information about the past history of the universe. The thermal character of the microwave background radiation suggests that the universe has expanded from a state of high temperature and density, and places constraints on such a big-bang cosmology. The observations of very weak helium lines in the spectra of certain stars in the halo of our galaxy are possibly due to a low primeval abundance of this element. However, the simplest model of a big-bang cosmology leads to much higher helium abundances, such as are observed in the solar system and in many stars. The production of helium can be reduced either by altering the early expansion rate or by introducing degenerate electron neutrinos. Observations of interstellar and intergalactic deuterium and He(4), and possibly even He(3) and Li(7), are needed to test the various models.
最近的两个观察结果似乎为宇宙的过去历史提供了关键信息。微波背景辐射的热特性表明，宇宙从高温和高密度的状态中膨胀而来，并对这种大爆炸宇宙学模型施加了限制。在我们星系晕中某些恒星的光谱中观测到的非常微弱的氦线可能是由于这种元素在原始时的丰度较低。然而，最简单的大爆炸宇宙学模型会导致更高的氦丰度，例如在太阳系和许多恒星中观察到的那样。氦的产生可以通过改变早期的膨胀率或引入简并电子中微子来减少。需要观测星际和星系间的氘和 He(4)，甚至可能还有 He(3)和 Li(7)，以检验各种模型。
