广州汽车学院Passage 5
The Univer's Invisible Hand
By Christopher J. Conlice
七夕英文Dark energy (暗能量) does more than hurry along the expansion of the univer. It also has a stranglehold on the shape and spacing of galaxies
What took us so long? Only in 1998 did astronomers discover we had been missing nearly three quarters of the contents of the univer, the so-called dark energy--an unknown form of energy that surrounds each of us, tugging at us ever so slightly, holding the fate of the cosmos in its grip, but to which we are almost totally blind. Some rearchers, to be sure, had anticipated that such energy existed, but even they will tell you that its detection ranks among the most revolutionary discoveries in 20th-century cosmology. Not only does dark energy appear to make up the bulk of the univer, but its existence, if it stands the test of time, will probably require the development of new theories of physics.doss
Scientists are just starting the long process of figuring out what dark energy is and what its implications are. One realization has already sunk in: although dark energy betrayed its existence through its effect on the univer as a whole, it may also shape the evolution of the univer'ssleek inhabitants--stars, galaxies, galaxy clusters. Astronomers may have been staring at its handiwork for decades without realizing it.
暗能量不仅仅会加速宇宙膨胀。它也对星系的形状和间隔有所束缚。
是什么让我们花费了那么长时间?直到1998年宇航员才发现我们几乎忽略了宇宙中四分之三的能源,所谓的暗能量—我们周围一种不为人知的能量,轻轻将我们拉住,掌控了宇宙的命运。但是,对此我们一无所知。事实上,一些研究者早已预料到,这种能量是存在的,但是,他们将告知你,这是20世纪宇宙学上革命性的发现。暗能量不仅是宇宙的一大组成部分,而且如果能经受时间的考验,它的存在很可能需要物理学最新理论发展来作为支撑。
科学家们正着手研究暗能量的本质和影响,其中一项发现是:暗能量通过对整个宇宙的影响暴露了它的存在,它也可以使宇宙中星系,银河系产生变化。宇航员们数几十年来也许
一直致力于它的影响,而忽略了它的存在。
Ironically, the very pervasiveness of dark energy is what made it so hard to recognize. Dark energy, unlike matter, does not clump in some places more than others; by its very nature, it is spread smoothly everywhere. Whatever the location--be it in your kitchen or in intergalactic space--it has the same density, about 10-26 kilogram per cubic meter, equivalent to a handful of hydrogen atoms. All the dark energy in our solar system amounts to the mass of a small asteroid, making it an utterly inconquential player in the dance of the planets. Its effects stand out only when viewed over vast distances and spans of time.日语翻译招聘
讽刺的是,暗能量无处不在,使人很难发现。暗能量不同于物质,它不是在空间中某处群聚成团,而是依据其特有的性质均匀地分散在各个地方。无论是你家的厨房里还是星系间,它的密度都一样,约每立方米10-26 公斤,相当于几个氢原子的重量。太阳系里所有的暗能量相当于一个小行星块,所以在行星的运行中,它是微不足道的角色。只有在遥远的地方长时间观察,暗能量的影响才突出。
xploreSince the days of American astronomer Edwin Hubble, obrvers have known that all but the nearest galaxies are moving away from us at a rapid rate. This rate is proportional to distance: the more distant a galaxy is, the faster its recession. Such a pattern implied that galaxies are not moving through space in the conventional n but are being carried along as the fabric of space itlf stretches [e "Misconceptions about the Big Bang," byCharles H. Lineweaver and Tamara M. Davis; Scientific American, March 2005]. For decades, astronomers struggled to answer the obvious follow-up question: How does the expansion rate change over time? They reasoned that it should be slowing down, as the inward gravitational attraction exerted by galaxies on one another should have counteracted the outward expansion.
自从美国天文学家爱丁文哈伯那个时代开始,研究人员就已经知道那些除了最近的星系之外,其他星系都在以很快的速率远离我们。速率与距离是成比例的,离我们越远的星系,移动越快。这暗示了在传统的意义上,星系没有从空间移动,而是顺应着空间本身的结构延伸着〔参见Charles H. Lineweaver和Tamara M. Davistuanp在《科学美国人》2005年3月号上撰写的〈你也误会了大霹雳〉〕数十年来,科学家努力地回答明显的随之而来的问题。膨
胀的速率会随着时间如何改变呢?他们的推断是当彼此星系对内部的外有引力施以影响,那么外部扩张就会受到阻碍,宇宙的膨胀速率就会减慢。
怎么安慰男朋友The first clear obrvational evidence for changes in the expansion rate involved distant supernovae, massive exploding stars that can be ud as markers of cosmic expansion, just as watching driftwood lets you measure the speed of a river. The obrvations made clear that the expansion was slower in the past than today and is therefore accelerating. More specifically, it had been slowing down but at some point underwent a transition and began speeding up [e "Surveying Space-time with Supernovae," by Craig J. Hogan, Robert P. Kirshner and Nicholas B. Suntzeff; Scientific American, January 1999, and "From Slowdown to Speedup," by Adam G. Riess and Michael S. Turner; Scientific American, February 2004]. This striking result has since been cross-checked by independent studies of the cosmic microwave background radiation by, for example, the Wilkinson Microwave Anisotropy Probe (WMAP).
第一个膨胀速率变化的明显观测证据是涉及遥远的超新星的。大量爆炸的恒星可以被当做
relea宇宙膨胀的标志,就像我们盯着浮木可以测量水速。观测结果清楚显示过去的膨胀速度比现在慢,因此它现在正在加速。更确切的说,宇宙膨胀确实曾经一度变慢,但在某个时刻经历一段过渡期后,便开始加速了。〔参见Craig J. Hogan, Robert P. Kirshner and Nicholas B. Suntzeff撰写的〈测量超新星时空〉和撰写的〈从减速到加速〉cheerio〕。这个显著的成果已经被其他关于宇宙微波背景辐射的个别研究反复检验过了,例如,威金森微波异向性探测器(WMAP)
Dark energy may be the key link among veral aspects of galaxy formation that ud to appear unrelated.
One possible conclusion is that different laws of gravity apply on supergalactic scales than on lesr ones, so that galaxies' gravity does not, in fact, resist expansion. But the more generally accepted hypothesis is that the laws of gravity are universal and that some form of energy, previously unknown to science, oppos and overwhelms galaxies' mutual attraction, pushing them apart ever faster. Although dark energy is inconquential within our galaxy (let alone your kitchen), it adds up to the most powerful force in the cosmos.