首页
登录
职称英语
From the beginning, the idea of a finite universe ran into its own o
From the beginning, the idea of a finite universe ran into its own o
游客
2025-02-22
33
管理
问题
From the beginning, the idea of a finite universe ran into its own obstacle,
the apparent need for an edge, a problem that has only recently been grappled
with. Aristotle’s argument, that the universe is finite, and that a boundary was
Line necessary to fix an absolute reference frame, held only until scientists wondered
(5) what happened at the far side of the edge. In other words, why do we not
redefine the "universe" to include that other side?
Riemann ingeniously replied by proposing the hypersphere, the three-
dimensional surface of a four-dimensional ball. Previously it was supposed that
the ultimate physical reality must be a Euclidean space of some dimension, and
(10) thus if space were a hypersphere, it would need to sit in a four-dimensional
Euclidean space that allows us to view it from the outside. But according to
Riemann, it would be perfectly acceptable for the universe to be a hypersphere
and not embedded in any higher-dimensional space; nature need not therefore
cling to the ancient notion. According to Einstein’s powerful but limited theory
(15) of relativity, space is a dynamic medium that can curve in one of three ways,
depending on the distribution of matter and energy within it, but because we are
embedded in space, we cannot see the flexure directly but rather perceive it as
gravitational attraction and geometric distortion of images. Thus, to determine
which of the three geometries our universe has, astronomers are forced to
(20) measure the density of matter and energy in the cosmos, whose amounts appear
at present to be insufficient to force space to arch back on itself in "spherical"
geometry. Space may also have the familiar Euclidean geometry, like that of a
plane, or a "hyperbolic" geometry, like that of a saddle. Furthermore, the
universe could be spherical, yet so large that the observable part seems
(25) Euclidean, just as a small patch of the earth’s surface looks flat.
We must recall that relativity is a purely local theory: it predicts the
curvature of each small volume of space-its geometry-based on the matter
and energy it contains, and the three plausible cosmic geometries are consistent
with many different topologies: relativity would describe both a torus and a
(30) plane with the same equations, even though the torus is finite and the plane is
infinite. Determining the topology therefore requires some physical
understanding beyond relativity, in order to answer the question, for instance,
of whether the universe is, like a plane, "simply connected", meaning there is
only one direct path for light to travel from a source to an observer. A simply
(35) connected Euclidean or hyperbolic universe would indeed be infinite-and seems
self-evident to the layman-but unfortunately the universe might instead be
"multiply-connected", like a torus, in which case there are many different such
paths. An observer could see multiple images of each galaxy and easily interpret
them as distinct galaxies in an endless space, much as a visitor to a mirrored
(40) room has the illusion of seeing a huge crowd, and for this reason physicists have
yet to conclusively determine the shape of the universe. [br] The author would regard the idea that the universe inhabits a spherical geometry as
选项
A、unimportant
B、unscientific
C、self-evident
D、plausible
E、unlikely
答案
E
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3967843.html
相关试题推荐
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Herlecturegaveasenseofhowemptytheuniverseis,inspiteofthe____numb
Doyouthinkit’simportanttoknowhowtouseacomputer? Definitely.Inworkp
Doyouthinkit’simportanttoreceiveagoodeducation? Yes,definitely.Agoo
Doyouthinkit’simportanttohaveenoughleisuretime? Definitely.Lifeisn’t
随机试题
Advertiserstendtothinkbigandperhapsthisiswhythey’realwayscoming
中国面临的最严峻的挑战之一就是人口老龄化(agingpopulation)。专家称在未来四十年内,中国老年人口将接近5亿,占据人口总数的三分之一。这无
某制造企业下设机修和供电两个辅助生产车间,采用交互分配法分配辅助生产费用。辅助生
不能溯源至SI单位的临床检验项目是A.葡萄糖 B.胆固醇 C.尿素 D.甲
简述现代企业人力资源管理各个历史发展阶段的特点。
杏苏散的药物组成包含A.石膏 B.薄荷 C.麦冬 D.前胡
劳动争议第三人须同时具备的条件有()。A.须在仲裁或诉讼活动已经开始、尚未终结时
根据建设项目法人责任制,新建项目正式成立项目法人的时间要求是()。A.申报项目建
女,20岁。因摔倒造成左尺骨鹰嘴骨折,行切开复位内固定。4周开始被动活动锻炼。1
甲建设单位与乙设计单位签订设计合同,约定设计费为200万元,甲按约定向乙支付了定
最新回复
(
0
)