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世界上最冷的物质是什么 – 译学馆
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世界上最冷的物质是什么

What is the coldest thing in the world? - Lina Marieth Hoyos

世界上最冷的物质不在南极
The coldest materials in the worldaren’t in Antarctica.
它们也不在珠穆朗玛峰的顶端
They’re not at the top of Mount Everest
或埋于冰川之下
or buried in a glacier.
它们在物理实验室里:
They’re in physics labs:
气体云的温度只比绝对零度高一点
clouds of gases held just fractions of a degree above absolute zero.
这比冰箱冷3.95亿倍
That’s 395 million times colderthan your refrigerator,
比液氮冷一亿倍
100 million times colderthan liquid nitrogen,
比外太空冷四百万倍
and 4 million times colderthan outer space.
如此低的温度为科学家们打开了一扇
Temperatures this low give scientists a window
了解物质内部运作的窗户
into the inner workings of matter,
使工程师们得以建造非常灵敏的仪器
and allow engineers to buildincredibly sensitive instruments
以告诉我们更多
that tell us more about everything from our exact
从我们在地球上的确切位置
position on the planet to what ’ s happening
到宇宙最深处正在发生的事情
in the farthest reaches of the universe.
我们怎样才能创造出这样的极端温度呢
How do we create suchextreme temperatures?
简单的说 减缓粒子运动
In short, by slowing downmoving particles.
当我们谈论温度时
When we ’ re talking about temperature,
我们实际上谈论的是运动
what we ’ re really talking about is motion.
构成固体 液体 气体的
The atoms that make up solids, liquids,
原子一直在运动
and gases are moving all the time.
原子运动得越来越快时 我们认为物质是热的
When atoms are moving more rapidly, we perceive that matter as hot.
当原子运动越来越慢时 我们认为物质是冷的
When they’re moving moreslowly, we perceive it as cold.
为了在日常生活中让热的物体或气体变冷
To make a hot objector gas cold in everyday life,
我们把它放进一个更冷的环境 比如冰箱
we place it in a colder environment,like a refrigerator.
热物体的一些原子运动
Some of the atomic motion
被转移到周围环境中
in the hot object is transferred to the surroundings,
并冷却下来
and it cools down.
但这是有限度的:
But there ’ s a limit to this:
即便是外太空也太暖而无法产生超低温
even outer space is too warm to create ultra-low temperatures.
因此 科学家找到了一种
So instead, scientists figured out
直接降低原子速度的办法
a way to slow the atoms down directly –
用激光束
with a laser beam.
在大多数情况下 激光束中的能量会使物体变热
Under most circumstances, the energy in a laser beam heats things up.
但需要十分精确
But used in a very precise way,
光束的动量能囚禁运动原子 使它们冷却
the beam’s momentum can stallmoving atoms, cooling them down.
这就是所谓的磁光阱
That’s what happens in a devicecalled a magneto-optical trap.
原子被注入真空室
Atoms are injected into a vacuum chamber,
而且磁场会把它们吸入中心
and a magnetic fielddraws them towards the center.
瞄准真空室中部的激光束
A laser beam aimedat the middle of the chamber
被调到恰当的频率
is tuned to just the right frequency
朝它移动的原子会吸收激光束中的光子
that an atom moving towards it will absorb a photon
并使其速度减缓
of the laser beam and slow down.
减速效应来自于
The slow down effect comes fromthe transfer of momentum
原子和光子之间的动量转移
between the atom and the photon.
一共有六束光束 垂直排列
A total of six beams,in a perpendicular arrangement,
确保截取各个方向运动的原子
ensure that atoms travelingin all directions will be intercepted.
在中心 光束相交的地方
At the center, where the beams intersect,
原子运动缓慢
the atoms move sluggishly,
好似被困在黏稠的液体中
as if trapped in a thick liquid —
发明它效果的研究人员称其为‘光学糖浆’
an effect the researchers who invented itdescribed as “optical molasses.”
像这样的磁光阱
A magneto-optical trap like this
可以把原子冷却到几微开
can cool atoms downto just a few microkelvins —
约-273摄氏度
about -273 degrees Celsius.
这项技术是在20世纪80年代发展起来的
This technique was developed in the 1980s,
为此做出贡献的科学家们
and the scientistswho’d contributed to it
在1997年获得了诺贝尔物理学奖
won the Nobel Prize in Physics in 1997for the discovery.
从那时起 激光冷却技术得到改进 甚至达到了更低的温度
Since then, laser cooling has been improved to reach even lower temperatures.
但为什么要使原子冷却这么多呢
But why would you wantto cool atoms down that much?
首先 冷原子可以成为很好的探测器
First of all, cold atoms can makevery good detectors.
由于能量很少
With so little energy,
他们对环境的波动十分敏感
they ’ re incredibly sensitive to fluctuations in the environment.
因此它们被用于
So they ’ re used
勘探地下石油和矿藏
in devices that find underground oil and mineral deposits,
它们也用于制作高度精密的原子钟
and they also makehighly accurate atomic clocks,
就像全球定位卫星卫星中使用的原子钟一样
like the ones usedin global positioning satellites.
其次 冷原子具有
Secondly,cold atoms holdenormous potential
探索物理学前沿的巨大潜力
for probing the frontiers of physics.
它们的高度灵敏度使其成为
Their extreme sensitivitymakes them candidates
未来太空探测器中探测引力波的候选者
to be used to detect gravitational wavesin future space-based detectors.
它们对研究原子和亚原子的研究也很有用处
They’re also useful for the studyof atomic and subatomic phenomena,
这需要测量原子能量的微小波动
which requires measuring incrediblytiny fluctuations in the energy of atoms.
当原子以每秒数百米的速度运动时
Those are drowned outat normal temperatures,
它们在常温下被淹没
when atoms speed aroundat hundreds of meters per second.
激光冷却可以将原子的速度减慢到
Laser cooling can slow atoms to
每秒几厘米——
just a few centimeters per second—
足够让原子量子效应引起的运动变得明显
enough for the motion caused by atomic quantum effects to become obvious.
超冷原子能使科学家们研究
Ultracold atoms have alreadyallowed scientists to study phenomena
诸如玻色——爱因斯坦凝聚这样的现象
like Bose-Einstein condensation,
其中原子几乎被冷却到绝对零度
in which atoms are cooled almostto absolute zero
并成为一种罕见的物质新状态
and become a rare new state of matter.
研究人员继续他们的探索
So as researchers continue
以了解物理定律
in their quest to understand the laws of physics
并解开宇宙的奥秘
and unravel the mysteries of the universe,
他们将在宇宙中最冷的原子的帮助下做到这一点
they ’ ll do so with the help of the very coldest atoms in it.

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世界上最冷的是什么?南极?或是珠穆朗玛峰顶?又或是冰箱?怎样才能产生这种冷物质呢?一起来看看吧

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