2019 August 4
Rumors of a Dark Universe
Image Credit: High-Z Supernova Search Team, HST, NASA
Explanation: Twenty-one years ago results were first presented indicating that most of the energy in our universe is not in stars or galaxies but is tied to space itself. In the language of cosmologists, a large cosmological constant — dark energy — was directly implied by new distant supernova observations. Suggestions of a cosmological constant were not new — they have existed since the advent of modern relativistic cosmology. Such claims were not usually popular with astronomers, though, because dark energy was so unlike known universe components, because dark energy’s abundance appeared limited by other observations, and because less-strange cosmologies without a signficant amount of dark energy had previously done well in explaining the data. What was exceptional here was the seemingly direct and reliable method of the observations and the good reputations of the scientists conducting the investigations. Over the two decades, independent teams of astronomers have continued to accumulate data that appears to confirm the existence of dark energy and the unsettling result of a presently accelerating universe. In 2011, the team leaders were awarded the Nobel Prize in Physics for their work. The featured picture of a supernova that occurred in 1994 on the outskirts of a spiral galaxy was taken by one of these collaborations.
影像提供: High-Z Supernova Search Team, HST, NASA
说明: 二十年前起陆续出现的一些研究成果，首次披露宇宙的大部分能量，并不在恒星与星系之内，而是在空间里。以宇宙学家的语言来说，遥远超新星观测的新结果暗指，宇宙有很大的宇宙常数（暗能量）。主张宇宙常数的学说并不新奇，它早在现代的相对论性宇宙论萌芽时，就已经存在了。然而宇宙常数的主张，并不特别受到天文学家的青睐。因为宇宙常数 和其他已知的宇宙组成非常不同，观测也显示暗能量并不多，而且未加入太多暗能量的寻常宇宙论，先前也能把观测资料诠释得很好。不过现在与先前有别的，是现在有声誉卓著的研究团队，用看似直接可靠的方法进行探索。在过去二十年之中，数个独立的天文研究团队不断地累积的观测数据，也看似证实了暗能量的存在，以及另一项令人不安的结果─我们的宇宙正在加速膨胀。这些团队的领导者，更因为这些成果而获颁2011年的诺贝尔物理奖。这幅记录了1994年一颗出现在螺旋星系外围的超新星之主题影像，就是由其中一个团队所拍摄的。