加载中…GMATOG16新增RC Passage26（Questions 137-139）
(2016-10-18 09:32:06)
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Q137-139
Most attempts by physicists to send
particles faster than the speed of light involve a remarkable
phenomenon called quantum tunneling, in which particles travel
through solid barriers that appear to be impenetrable. If you throw
a ball at a wall, you expect it to bounce back, not to pass
straight through it. Yet subatomic particles perform the equivalent
feat. Quantum theory says that there is a distinct, albeit small,
probability that such a particle will tunnel its way through a
barrier; the probability declines exponentially as the thickness of
the barrier increases. Though the extreme rapidity of quantum
tunneling was noted as early as 1932, not until 1955 was it
hypothesized－by Wigner and Eisenbud－that tunneling particles
sometimes travel faster than light. Their grounds were calculations
that suggested that the time it takes a particle to tunnel through
a barrier increases with the thickness of the barrier until
tunneling time reaches a maximum; beyond that maximum, tunneling
time stays the same regardless of barrier thickness. This would
imply that once maximum tunneling time is reached, tunneling speed
will increase without limit as barrier thickness increases. Several
recent experiments have supported this hypothesis that tunneling
particles sometimes reach superluminal speed. According to
measurements performed by Raymond Chiao and colleagues, for
example, photons can pass through an optical filter at 1.7 times
the speed of light.
137.The author of the passage mentions
calculations about tunneling time and barrier thickness in order
to
A.suggest that tunneling time is unrelated
to barrier thickness
B.explain the evidence by which Wigner and
Eisenbud discovered the phenomenon of
tunneling
C.describe data recently challenged by
Raymond Chiao and colleagues
D.question why particles engaged in
quantum tunneling rarely achieve extremely high
speeds
E.explain the basis for Wigner and
Eisenbud’s hypothesis
138.The passage implies that if tunneling
time reached no maximum in increasing with barrier thickness,
then
A.tunneling speed would increase with
barrier thickness
B.tunneling speed would decline with
barrier thickness
C.tunneling speed would vary with barrier
thickness
D.tunneling speed would not be expected to
increase without limit
E.successful tunneling would occur even
less frequently than it does
139.Which of the following statements
about the earliest scientific investigators of quantum tunneling
can be inferred from the passage?
A.They found it difficult to increase
barrier thickness continually.
B.They anticipated the later results of
Chiao and his colleagues.
C.They did not suppose that tunneling
particles could travel faster than
light.
D.They were unable to observe instances of
successful tunneling.
E.They made use of photons to study the
phenomenon of tunneling.
文章结构分析：
Most attempts by physicists to send
particles faster than the speed of light involve a
remarkable phenomenoncalled quantum
tunneling, in which particles travel through solid barriers
that appear to be impenetrable. If you throw a ball at a wall, you
expect it to bounce back, not to pass straight through it. Yet
subatomic particles perform the equivalent
feat.
现象：量子隧穿效应，就是粒子穿越了本似乎无法穿越的壁垒。论据是比较论证，球无法穿过墙壁，但是粒子却能穿越“墙壁”。
Quantum
theory
理论依据
Though the extreme rapidity of quantum
tunneling was noted as early as 1932, not until 1955 was
ithypothesized－by
Wigner and Eisenbud－that tunneling particles sometimes travel
faster than light. Theirgrounds were
calculations that suggested that the time
it takes a particle to tunnel through a barrier increases with the
thickness of the barrier until tunneling time reaches a maximum;
beyond that maximum, tunneling time stays the same regardless of
barrier thickness. This would imply
that once maximum tunneling time is
reached, tunneling speed will increase without limit as barrier
thickness increases.
提出QT的假设和根据
Several recent experiments have
supported this hypothesis
论据支持假设。
总结：整篇文章是分析类的，分析的是quantum
tunneling这个现象的理论依据、被发现的过程。
词汇&背景知识：
quantum
tunneling：量子隧穿效应，是一种量子特性，是电子等微观粒子能够穿过它们本来无法通过的“墙壁”的现象。按照经典理论，总能量低于势垒是不能实现反应的。但依量子力学观点，无论粒子能量是否高于势垒，都不能肯定粒子是否能越过势垒，只能说出粒子越过势垒概率的大小。它取决于势垒高度、宽度及粒子本身的能量。能量高于势垒的、运动方向适宜的未必一定反应，只能说反应概率较大。而能量低于势垒的仍有一定概率实现反应，即可能有一部分粒子(代表点)穿越势垒(也称势垒穿透barrier
penetration)，好像从大山隧道通过一般。
subatomic particle:次原子粒子又称亚原子粒子，指结构比原子更小的粒子。其中包括原子的组成部分如电子、质子和中子（质子和中子本身又是由夸克所组成的粒子）和放射和散射所造成的粒子如光子、中微子和渺子，以及许多其它奇特的粒子。总的来说，次原子粒子可能是电子、中子、质子、介子、夸克、胶子、光子等等。
feat：壮举，技艺
exponentially：呈几何级数地，以指数级的方式
photon：光子
137.The author of the passage mentions
calculations about tunneling time and barrier thickness in order
to
写作意图题，为什么要写对tunneling time和barrier
thickness的计算，定位句子“Their grounds
werecalculations that suggested that the time it takes a
particle to tunnel through a barrier increases with the thickness
of the barrier until tunneling time reaches a
maximum”，句子内部就有答案，是作为their
grounds的，所以选E。
A.suggest that tunneling time is unrelated
to barrier thickness
B.explain the evidence by which Wigner and
Eisenbud discovered the phenomenon of
tunneling
C.describe data recently challenged by
Raymond Chiao and colleagues
D.question why particles engaged in
quantum tunneling rarely achieve extremely high
speeds
E.explain the basis for
Wigner and Eisenbud’s hypothesis
138.The passage implies that if tunneling
time reached no
maximum in increasing with barrier
thickness, then
先扫一眼选项会发现这道题要求我们判断的是tunneling
tim、thickness和tunneling speed
间的关系，先定位到原文讲到该关系的句子“once maximum tunneling time is reached,
tunneling speed will increase without limit as barrier thickness
increases.
A.tunneling speed would increase with
barrier thickness
B.tunneling speed would decline with
barrier thickness
C.tunneling speed would vary with barrier
thickness
D.tunneling speed would
not be expected to increase without
limit
E.successful tunneling would occur even
less frequently than it does
139.Which of the following statements
about the earliest scientific
investigators of quantum tunneling can be
inferred from the passage?
细节题，首先要定位到文中谁是earliest investigators of
QT,定位句子“Though the extreme rapidity of quantum
tunneling was noted as early as 1932, not until 1955 was it
hypothesized－by Wigner and
Eisenbud－that tunneling particles sometimes travel
faster than light.”文中没有直接出现investigators，但出现了时间as early
as，所以1932年的研究者是最早的，关于他们可以知道的信息是，他们最早于1932年注意到QT的速度之快，但是直到1955年，才有人假设tunneling
particles的速度能够超过光速，意思也就是说earliest
investigators是没有料到particles的速度会超过光速的。选。
A.They found it difficult to increase
barrier thickness continually.
无中生有，没说到这一点，无能无端假设有。
B.They the later results of
Chiao and his colleagues.
不合逻辑，前人不可能料到未来的人，而且是某个具体的人会做出什么发现。
C.They did not suppose
that tunneling particles could travel faster than
light.
D.They
were
quantum tunneling was
noted，证明观察到了，而不是没观察到。
E.They
是recent investigators
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