首页
登录
职称英语
It is hardly surprising that something called dark energy is hard to study.
It is hardly surprising that something called dark energy is hard to study.
游客
2024-05-31
3
管理
问题
It is hardly surprising that something called dark energy is hard to study. It is important, though. If it exists at all, it makes up about three-quarters of the stuff in the universe. And if it does not exist, then existing theories of physics will have to be useless.
The latest evidence that dark energy really does exist was produced on December 16th by Alexey Vikhlinin, of the Smithsonian Observatory in Cambridge, Massachusetts, and his colleagues. They used an orbiting X-ray telescope called Chandra to study the way that groups of galaxies grow. They discovered that this growth is restrained in exactly the way that dark-energy theory predicts.
The idea of dark energy was dreamed up ten years ago, to explain why the expansion of the universe that began with the Big Bang seems to be accelerating, rather than slowing down. That unexpected finding was the result of studies of supernovas (超新星) whose apparent brightness (and therefore distance) did not match the previous theory. Dark energy causes the acceleration by pushing space itself apart, altering the distances to the supernovas as it does so.
Dark energy is also a convenient explanation for another curiosity. Geometrically, space is flat. For it to be held that way, rather than getting more and more curved over time, the amount of matter and energy it contains must be at a particular, critical density. Without the dark energy needed to explain the acceleration, the universe would have only a quarter of the necessary density. It is therefore a relief that Dr Vikhlinin’s results agree with the theory: the pushing apart of space that dark energy causes makes it harder than it otherwise would be for galactic clusters(银河星团) to grow.
This result does not bring physicists much closer to understanding what dark energy actually is. The favored explanation is the so-called universal constant -- an as-yet-unobserved consequence of the general theory of relativity. But that theory predicts a force far more powerful than the one actually seen. So the truth is that physicists are still in the dark. [br] Where did the physicists get the fact that universe expansion is accelerating?
选项
答案
groups of galaxies grow.
解析
由定位句可知,物理学家研究超新星时得到了这一出乎意料的发现。又根据句中指示代词“that”的指代关系,可知“出乎意料的发现”是指宇宙扩张速度加快,从而推知研究学家们是通过对超新星的研究发现宇宙扩张在加速这一事实的,故本题答案是From the result of studies of supernovas。
转载请注明原文地址:https://tihaiku.com/zcyy/3614011.html
相关试题推荐
HardlyhadMikefoundhispassport______(他就发现护照三个月前就已经到期了).whenhediscovered
[originaltext]W:Oh,Jack,I’mgladIcalledyou.IwanttotellyouIhaveto
[originaltext]W:Oh,Jack,I’mgladIcalledyou.IwanttotellyouIhaveto
Agreatdealofattentionisbeingpaidtodaytothesocalleddigitaldivid
Agreatdealofattentionisbeingpaidtodaytothesocalleddigitaldivid
Seeingthebranches______(几乎不能承受雪的重量,他找了些竹竿用来)supportthem.couldhardlysust
[originaltext]W:Dr.Smith.IneedtoaskyouaboutsomethinginChapter12.We
[originaltext]W:Dr.Smith.IneedtoaskyouaboutsomethinginChapter12.We
[originaltext]M:Icanhardlybreathe.Wouldyoupleaseputyourcigaretteout?
[originaltext]M:Icanhardlybreathe.Wouldyoupleaseputyourcigaretteout?
随机试题
WhywasRobertFletchersuingartistPeterDoig?[originaltext]CollectorRobe
Little_______whatwasupsettingme.A、mayherealizeB、herealizesC、hemayrea
()是企业薪酬管理的最基本前提,要求企业实施的薪酬制度符合国家、省、自治区的法
A.学龄期后开始出现紫绀 B.生后不久即出现下肢较上肢为轻的紫绀 C.学龄期
某男性锅炉操作工,在一个通风不良环境中,连续工作3~4小时后,突感头痛和头晕。查
关于干扰素抗病毒治疗的禁忌证,不正确的是A:有心、肝、肾功能不全患者 B:肝硬
下列厂房中,耐火等级不应低于二级的是()。A.某独立建造的建筑面积为280m2
特性列举法的实施步骤不包括( )。A.将对象的特性或属性全部写出来 B.从三
对真正的利他主义最有可能进行解释的理论是A.共情理论 B.社会规范理论 C.
YUHUI,aboisterousfour-year-oldhivi
最新回复
(
0
)