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暗物质:怎样解释恒星的速度? – 译学馆
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暗物质:怎样解释恒星的速度?

Dark matter: How does it explain a star's speed? - Don Lincoln

在所有通过望远镜观测到的星体中
Of all the spectacles mankind has viewed through a telescope,
没有什么比螺旋状的银河更可爱的了
there are few lovelier than a spiral galaxy.
雄伟的星河漩涡旋转着,就像进行着一场庄严的可预测的舞蹈
Majestic whirlpools of stars, they rotate in a stately and predictable dance.
事实上我们在望远镜中看见的数千万计的螺旋状银河
The fact that we see many billions of them in our telescopes
告诉我们它们都是相同并且稳定的
tells us they are both common and stable.
令人感到惊讶的是相当容易明白这些宇宙纸风车的运行原理
It is perhaps surprising that it is relatively easy to understand the inner workings of these cosmic pinwheels.
在十七世纪末牛顿结合物理原理得出结论
By combining physical principles worked out by Sir Isaac Newton in the late 17th century,
随着星系中以质量的量的被观测
with the observed amount of mass in a galaxy,
科学家们可以计算出这些星系旋转的速度
scientists can calculate the rates at which these galaxies rotate.
通过这些技术,天文学家推测恒星在
Using these techniques, astronomers predict how fast stars at different distances from the center of the galaxy should move.
恒星离中心越近转得越慢
Stars very close to the center move slowly.
因为在它们与银河中心之间的物质太少而不能产生足够的引力
That’s because there is very little mass between them and the center of the galaxy to pull them along.
离中心远一点的恒星会转的更快
Stars a bit further away move faster,
因为它们与中心之间的很多星体会产生引力来牵引它们运动
because they are being pulled by all of the stars in between them and the center.
当距离足够远时,星体的速度预计又会慢下来
As we get really far away, the stars are predicted to move slowly again.
太远的距离会使星体间引力变得很弱
Their great distance reduces gravity to a gentle tug,
所以它们悠闲地在轨道上运行
so they move leisurely in their orbits.
知道这点后,科学家就能通过观察银河来测量星体运动的多快
Knowing this, scientists looked at the galaxies and measured how fast stars were moving.
让他们惊讶的是,他们发现当星体越接近银河中心时,运动是符合预测的
To their surprise, they found that while the stars closer to the center of the galaxy behaved as predicted,
远离时则速度太快
those further away moved far too quickly.
这个发现推翻了传统的引力与运动关系的理论
This observation was devastating to the tradtional theories of gravity and motion.
如果这些星体的速度像测量的这么快
If the stars were moving as fast as their measurement suggested,
银河就会把自己撕裂
galaxies should have torn themselves apart.
面对这个危机,天文学家和物理学家们急需找到他们计算中的问题
It was a crisis, and astronomers and physicists scrambled to find a mistake in their calculation.
牛顿的万有引力定律错了吗?
Was Newton’s theory of gravity wrong?
牛顿运动定律错了吗?
Was his theory of motion wrong?
还是说可能是天文学家把银河系的质量算错了?
Or was it possible that astronomers had incorrectly measured the galaxy’s mass?
研究了所有的可能,都是符合的,除了一个
All options were investigated, and all were ruled out. Except one.
今天,科学家相信答案在于之前未知的一种物质,暗物质
Today, scientists believe that the answer lies in a previously unknown kind of matter, called dark matter.
科学家设想的暗物质是像云一样的,它包裹了银河的大部分
This dark matter can be envisioned as a cloud which surrounds most galaxies.
这种物质非常的不同寻常,它受万有引力影响
This matter is very unusual. It is affected by gravity,
但它对于可见光和其他各种形式的电磁射线是不可见的
but it is invisible to visible light and all other forms of electromagnetic radiation.
它的名字“暗物质”就是源于这种物质不能放射或吸收光
The name ‘dark matter’ originates in this form of matter’s inability to emit or absorb light.
暗物质增加了银河系的引力
Dark matter adds to the gravity of the galaxy
解释了远离银河中心的星星的轨道速度
and explains the orbital speed of stars far from the galactic center.
暗物质至今没有被直接观察到
Dark matter has not yet been directly observed,
但科学家认为这很可能是真实存在的
but scientists believe that it is likely to be real,
大部分原因是其他的可能项已经被排除
mostly because the other options have been ruled out.
天文学家和物理学家仍在通过各种方式寻找
Using dozens of approaches, astronomers and physicists continue to search for direct evidence
能证明暗物质假设正确的直接证据,这是21世纪物理研究问题中最重要的问题之一
that would prove that the dark matter hypothesis is true.This question is one of the most important physics research questions of the 21st century.

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