首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
考研
Familiar as it may seem, gravity remains a mystery to modern physics. Despite several decades of trying, scientists have failed
Familiar as it may seem, gravity remains a mystery to modern physics. Despite several decades of trying, scientists have failed
admin
2015-06-24
29
问题
Familiar as it may seem, gravity remains a mystery to modern physics. Despite several decades of trying, scientists have failed to fit Einstein’s general theory of relativity, which describes how gravity holds big objects together, with the quantum mechanics (an extension of statistical mechanics based on quantum theory) he pioneered, which describes the tiny fundamental particles of whichmatter consists and the forces by which they interact.Recent discoveries have highlighted further problems.
Many physicists are therefore entertaining the idea that Einstein’s ideas about gravity must be wrong or at least incomplete. Showing exactly how and where the great man erred is the task of the scientists who gathered at the "Rethinking Gravity" conference at the University of Arizona in Tucson this week.
One way to test general relativity is to examine ever more closely the assumptions on which it rests, such as the equivalence principle: that gravity accelerates all objects at the same rate, regardless of their mass or composition. This principle was famously demonstrated by Galileo Galilei some 400 years ago when he simultaneously dropped cannon and musket balls, and balls made of gold, silver and wood, from the Tower of Pisa. Each appeared to hit the ground at the same time.
A more precise test requires a taller tower. In effect, researchers are sending balls all the way to the moon and back. Tom Murphy, of the University of California, San Diego, and his colleagues fire laser beams from the deserts of New Mexico at reflectors placed on the moon by American and Russian spacecraft in the late 1960s and early 1970s. They use a telescope to capture the small fraction of the light that returns. Because the speed of light is known, they can calculate the distance between the Earth and the moon from the time taken for light to pass through it.
According to general relativity, because the Earth and the moon orbit the sun, they should "fall" towards it at the same rate, in the same way as Galileo’s balls fell to the ground. By repeatedly measuring the distance between them, scientists can calculate the orbits of the Earth and the moon around the sun relative to each other. If the equivalence principle were violated, the moon’s orbit around the Earth would not appear straight, either towards or away from the sun So far, Dr Murphy told the conference, these experiments have merely confirmed the equivalence principle to one part in 10 trillion. Dr Murphy and his colleagues hope that even more precise measurements could ultimately show general relativity to be only approximately correct. This would usher in a new revolution in physics.
Galileo Galilei’s experiment at the Tower of Pisa around 400 years ago
选项
A、was one way of testing Einstein’s general theory of gravity.
B、illustrated the insignificance of mass and composition of an object.
C、acted as a well-known example to testify the equivalence principle.
D、showed that all objects on Earth were influenced by gravity.
答案
C
解析
事实细节题。根据Galileo Galilei和400 years ago定位到第三段。其中提到大约400年前伽利略在比萨斜塔的著名实验证明了等效原理,C项与此意相同。A项“是检验爱因斯坦广义相对论的一种方法”与第三段首句内容不符,故排除;B项“证明了物体的质量和成分毫无意义”属于推理过度:伽利略的实验是为了证明“在重力作用下,所有物体不分质量或成分,都具有相同的加速度”,不是宽泛地讲引力的作用,故D排除。
转载请注明原文地址:https://jikaoti.com/ti/flFRFFFM
0
考研英语一
相关试题推荐
TheChangeofHealthIndustryPatternBackin1979,afatunhealthypropertydeveloper,MelZuckerman,andhisexercise-fana
Parents’MistakeIdeasAboutAsthmaDiseaseWatchingachildstruggletobreatheduringanasthmaattackisfrighteningfor
Writeanessayof160—200wordsbasedonthefollowingdrawing.Inyouressay,youshould1)describethedrawingbriefly,2)ex
Whenspeakingaboutsciencetoscientists,thereisonethingthatcanbesaidthatwillalmostalwaysraisetheirindignation,
Whenspeakingaboutsciencetoscientists,thereisonethingthatcanbesaidthatwillalmostalwaysraisetheirindignation,
Helpingterminallyillpeopletocommitsuicideshouldbemadelegalunderstrictnewsafeguards,amajorindependentreportis
Thesuccessstoryoftopinvestorsandexecutivesisastapleofbusinessbooksandmagazines.【C1】______researchsuggestswesho
Animportantfactorofleadershipisattraction.Thisdoesnotmeanattractivenessintheordinarysense,forthatisabornqua
Overthepastcentury,allkindsofunfairnessanddiscriminationhavebeencondemnedormadeillegal.【F1】Butoneinsidiousform
Lifeisunfair,aseventheBibleacknowledges.Wecan’tallhitabaseballlikeDiMaggioorsingliketheBeatles.Buthowmuch
随机试题
手三阳经与足三阳经交接在()
男,45岁,因心力衰竭入院。服用洋地黄数日后,患者述病房里的白色墙壁变成黄色的了。该病人最可能的情况是
电路如图所示,该电路完成的功能是()。
本题考核知识点:交互分配法、平行结转分步法甲公司是一个模具生产企业,只生产一种产品,产品在两个车间进行,第一车间为第二车间提供半成品,第二车间加工成产成品,每件产成品耗用2件半成品。甲公司用平行结转分步法计算产品成本,月末盘点,按约当产量法在完工产品和在
材料一:一日,王教授应邀到甲机关举办一场关于职业道德与行为规范关系的专题讲座。会场里时常响起手机声,会议主持人不断地用手势提醒大家关闭手机,甚至打断学者讲座,让大家保持会场秩序。次日王教授到乙机关举办同样的讲座,会场秩序井然,听讲座的每个人都自觉
甲、乙、丙三人共处理文件48份,已知丙比甲多处理8份,乙比甲多处理4份,则甲、乙、丙处理文件的比是:
20世纪80年代以来,以市场为取向的改革使人力资本的市场价值得以实现,居民的教育收益率从较低水平提高到10%左右,这也是不同受教育水平劳动者之间收入差距扩大的重要原因。随着受教育程度提高,高学历劳动者不再稀缺,教育收益逐渐稳定,高低学历的劳动者工资比不再上
A.briefB.entriesC.intoA.beclassified【T1】______fourtypesB.【T2】______formofweblogC.【T3】______onablogareorgan
18世纪的法国启蒙思想家中最为著名的有伏尔泰、______、______和以狄德罗为代表的百科全书派。
FewAmericansstayinonepositionoroneplaceforalifetime.Wemovefromtowntocityto【T1】______,fromajobinoneregio
最新回复
(
0
)