Vikings (北欧海盗) , like birds and butterflies, may have used polarized light in the form of rock crystals(晶体) to navigate on foggy days, according to researchers Sunday.
It’s a known fact that Vikings crossed the oceans using sundials (日晷), but on an overcast or a foggy day sundials would have been useless. Many researchers theorized that Viking sailors found the sun on foggy days by using sunstones. But no one had tested the theory until recently.
A team sailed the Arctic Ocean aboard the Swedish icebreaker Oden and found sunstones – rock crystals – could indeed point the way under foggy and cloudy conditions.
“Crystals such as cordierite, calcite or tourmaline work like polarizing filters (滤光器) , changing in brightness and color as they detect the angle of sunlight. From these changes, Vikings could have accurately determined where the polarized sky light was coming from and pinpointed the direction of the sun, ” said biophysicist Gabor Horvath.
“Under foggy or cloudy conditions a Viking navigator could have guessed the position of the sun hidden by clouds or fog by determining the sky light polarization in two sky points… and could have guessed the position of the invisible sun,” said Horvath, of Eotvos University in Budapest. “Although all these are pure imagination, researchers can test the scientific possibility of such a navigation method.”
In previous studies Horvath and colleagues demonstrated Vikings might have required some kind of device, other than just the naked eyes, to accurately guess the position of the sun on cloudy days.
Their latest findings, published in the April issue of the journal Proceedings of the Royal Society A, suggest that if Vikings were to have sunstones onboard, the Norsemen could have used them to determine where to go.
Archaeologists (考古学家) have found Viking sundials, but have yet to find any remains of sunstones.
The sunstone theory was first proposed in 1966 by the Danish archaeologist Thorkild Ramskou. Yet the only hint that Vikings used sunstones comes from a mention in a Viking legend.
“Although there is neither archaeological, nor historical evidence supporting this theory, it is so nice and splendid that it can easily trap the fantasy and imagination of both professional and amateur scientists,” Horvath told Live Science.
Along with Vikings, birds and butterflies are also thought to use polarized light to orient themselves, along with other cues such as the planet’s magnetic field.
73. What do the underlined words “cordierite, calcite or tourmaline” mean?
A. Sunstones.
B. Polarized light.
C. Sundials.
D. The Earth’s magnetic field.
74. What do Horvath’s underlined words in Para 10 imply?
A.Many scientists have been cheated by the theory.
B.The theory is too nice and splendid to be believed.
C.The theory is quite reasonable yet needs to be proved.
D.We cannot find evidence to support the theory.
75. Which of the following can be best used as the title of the passage?
A.a special usage of the sunstones.
B.A great theory made in this century.
C.Birds guided Vikings crossing the oceans.
D.Vikings may have navigated like birds.

星期日，根据研究者们的看法，北欧海盗可能曾经使用过岩石晶体产生的偏振光在雾天导航，就像鸟儿和蝴蝶那样。

众所周知，北欧海盗利用日晷穿越大洋 ，但遇到阴云密布、浓雾满天的日子，日晷就毫无用处。许多研究人员推测，在大雾天，北欧海盗水手们借助日长石寻找太阳。但此前从未有人对此推测做出验证，直到最近。

一队（研究人员）搭乘瑞典破冰船奥登号在北冰洋上航行，他们发现日长石——岩石晶体（的总称）——的确能够在大雾和多云的天气下指示方向。

“堇青石、方解石、电气石等岩石晶体就好像偏振滤光器那样，会根据太阳光线入射的不同角度改变亮度和色泽。根据这些变化，北欧海盗也许能够准确确定天上的偏振光来自何方，并据此准确找出太阳的方向，”生物物理学家盖博·霍瓦特说道。

“在大雾或多云的情况下，北欧海盗的导航员也许能够根据天空中两个不同点位的偏光分极情况来猜出躲在云雾间的太阳的位置……甚至可能猜出隐而未现的太阳到底在哪。”布达佩斯艾奥特沃斯大学的霍瓦特说道：“虽然这一切都纯粹是猜想，但是研究人员可以验证这种导航方式在科学上的可能性。”

在以往的研究中，霍瓦特及其同事证实了北欧海盗除了使用肉眼观察外，可能需要借助某种装置，以便在多云的天气里准确推测太阳的位置。

他们的最新研究结果发表于4月号的《皇家学会纪要》杂志上，他们推测，如果北欧海盗将日长石装到船上，他们就可能借助它们指引航向。

考古学家已经发现了北欧海盗们使用的日晷，但尚未找到任何日长石的遗迹。

关于（使用）日长石（导航的）理论，最初是由丹麦考古学家托基尔德·拉姆斯库于1966年提出。然而，关于北欧海盗曾使用过日长石的唯一暗示，来自其传说中的一个表述。

“尽管此理论尚无考古发现和历史文献佐证，但是它如此巧妙而天衣无缝，轻易地就让专业的科学家和业余的科学爱好者对它充满痴迷与想像。”霍瓦特（接受）《活力科学》（杂志采访时）说。

不仅是北欧海盗，人们相信鸟儿和蝴蝶们除了依赖地球磁场等指示外，也会利用偏振光来指引方向。


73、下划线的“堇青石、方解石或电气石”是什么？
　　A、日长石
　　B、偏振光
　　C、日晷
　　D、地球磁场
　　选择：A。

74、第十段中，下划线的霍瓦特所说的话意味着什么？
　　A、许多科学家都被这一理论骗了。
　　B、这个理论过于巧妙而天衣无缝，使人难以置信。
　　C、这个理论很有道理，但尚待证实。
　　D、我们无法找到证据，以支持这一理论。
　　选择：C。

75、下列哪个最适合用作本文标题？
　　A：日长石的特殊用途
　　B：本世纪最伟大的理论
　　C：鸟儿引导北欧海盗穿越大洋
　　D：北欧海盗可能像鸟儿那样导航
　　选择：A。