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
31
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/3353281.html
相关试题推荐
Proceedingwithoutadefiniteplanforupcominglabornegotiations,likethefir
Inadditiontoconventionalgalaxies,theuniversecontainsverydimgalaxiesth
Inadditiontoconventionalgalaxies,theuniversecontainsverydimgalaxiesth
Inadditiontoconventionalgalaxies,theuniversecontainsverydimgalaxiesth
Atthebeginningofatrip,thetankofDianascarwasfilledwithgasolinetoh
Thenumbers3,10,17,24,31and38arethefirstsixtermsofaninfinitesequ
A、infinitespace,bydefinition,canexistbutcannotbeobservedfromanextern
INFINITY:A、minutedifferenceB、deficientcapacityC、limitedareaD、indefinitevo
DEBACLE:A、definitesuppositionB、outspokenreplyC、completetriumphD、partialco
GRANDILOQUENT:A、vulgarB、valuableC、guardedD、indefiniteE、idiomaticC
随机试题
WhyPeopleBuyWhydopeoplebuy?Whydop
Theageofgildedyouthisover.Today’sunder-thirtiesarethefirstgenerat
从颞窗检查颅底动脉,经常表现为断续的血流信号,较难显示的动脉是A.大脑中动脉
下列哪项不是慢性盆腔炎的临床表现A.少腹一侧或双侧隐痛,反复发作 B.突然少腹
信息焦虑:指人们在过量信息包围下因为难以获取、处理、利用所需信息而产生的厌倦、烦
在不同的社会经济条件、城市自然条件和建设条件下,不同城市的道路系统有不同的发展形
行业分类的依据主要是公司收入或利润的来源比重,目前我国常见的分类标准包括()。
其他合作机构风险的防控措施包括()。 A.深人调查,选择讲信用、重诚信
2017年3月1日,郑某到甲公司工作,6月1日甲公司与郑某签订了2年
公路水运工程生产安全重大事故隐患排查治理的责任主体是( )。A.交通运输主管部门
最新回复
(
0
)