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
2024-01-11
39
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] According to the passage, an important limitation of relativity theory is that
选项
A、it fails to describe space on a non-local level, complicating attempts to determine the geometrical model of the universe
B、it cannot account for the possibility that the universe may be multiply- connected instead of singly-connected
C、it yields inconsistencies in spatial topology equations, discriminating unnecessarily between the torus and the plane
D、it creates the illusion that observable space is curved, when in fact the universe may be Euclidean and planar
E、it does not provides sufficient variety in geometrical models to describe all the possible ways in which space may curve
答案
A
解析
转载请注明原文地址:https://tihaiku.com/zcyy/3353279.html
相关试题推荐
Atthebeginningofatrip,thetankofDianascarwasfilledwithgasolinetoh
theaverageofnconsecutiveintegersbeginningwith1is12QuantityA:nQuant
A、infinitespace,bydefinition,canexistbutcannotbeobservedfromanextern
INFINITY:A、minutedifferenceB、deficientcapacityC、limitedareaD、indefinitevo
DEBACLE:A、definitesuppositionB、outspokenreplyC、completetriumphD、partialco
GRANDILOQUENT:A、vulgarB、valuableC、guardedD、indefiniteE、idiomaticC
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
Fromthebeginning,theideaofafiniteuniverseranintoitsowno
INFINITY:A、minutedifferenceB、deficientcapacityC、limitedareaD、indefinitevo
随机试题
Thereisonepassageinthissectionwith10questions.Readthepassagequi
DearDigitalDiary—LifeloggingintheInternetAgeFromslee
关于旅行社经营核算的审核方法,下列说法错误的是()。A.单团核算是指旅行社就
农用地是指直接用于农业生产的土地,包括()。A.耕地 B.林地、草地 C
无血缘关系的同种器官移植中,急性排斥反应难以避免的主要原因是A.受者的免疫功能常
弱式有效市场检验的方法包括()。A.股票价格的时间序列分析 B.股票价格变化的
2005年某公司支付每股股息为1.80元,预计在未来的日子里该公司股票的股息按每
提高房地产经纪信息的(),一方面要对信息库进行及时的更新和维护,另一方面要提高
女性,40岁,反复右上腹部痛20余年,再发伴恶心、呕吐3天,体温39℃,B超示急
有关承诺构成要件的叙述,不正确的是()。A:承诺须由受要约人或其代理人作出
最新回复
(
0
)