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
19
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] Which of the following best describes the relationship of the second paragraph to the first?
选项
A、The second paragraph limits the applicability of the theoretical method described in the first paragraph.
B、The second paragraph provides further elaboration on why an assertion made at the end of the first paragraph proves true in most cases.
C、The second paragraph provides additional information in support of a hypothesis stated in the first paragraph.
D、The second paragraph provides an example of a case in which the assumption described in the first paragraph is warranted.
E、The second paragraph describes a phenomenon that has the same cause as the phenomenon described in the first paragraph.
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3967839.html
相关试题推荐
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
INFINITY:A、minutedifferenceB、deficientcapacityC、limitedareaD、indefinitevo
Likethetheoryofevolution,thebig-bangmodeloftheuniverse’sformationhas
Evidencethattheuniverseisexpanding(i)______ourperceptionofthecosmosan
Herlecturegaveasenseofhowemptytheuniverseis,inspiteofthe____numb
Hydrogenisthe____elementoftheuniverseinthatitprovidesthebuildingbl
Doyouthinkit’simportanttoknowhowtouseacomputer? Definitely.Inworkp
Areyousatisfiedwithyourjob? Yes,definitely.I’velearnedalotinmycomp
Doyoulikemusic? Yes,definitely.I’mamusiclover.Ioftenlistentomusic
随机试题
Thecomplaintwouldbemore______ifthecustomercouldshowusthereceiptofth
Itisnotlongsinceconditionsinthemineswereworsethantheyarenow.T
Shehasbeenworkinginthisfactory______.A、in1980B、after1980C、since1980D
For14yearsafterherspouse’sdeath,shesawthe_________meaningofherlife
1型糖尿病患者的主要死亡原因是()。
采用背俞穴治疗骨蒸、潮热,应首选A.肝俞 B.肺俞 C.脾俞 D.
暴发型流脑脑膜脑炎型对症治疗不正确的是A.退热、止惊 B.补液 C.有呼吸衰
合理用药的经济原则内涵主要有A.不滥用药物 B.有利于环保 C.使用方法简单
根据企业所得税的规定,下列说法正确的有()。A.创业投资企业采取股权投资方
建设工程项目投资决策后,控制工程造价的关键在于()。A.工程设计 B.工
最新回复
(
0
)