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中子怎样改变了一切? – 译学馆
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中子怎样改变了一切?

How Neutrons Changed Everything

现在我们有核武器和核电站
Now that we have nuclear weapons and nuclear
你也许会觉得我们总将
power plants you might think that it was always
不可避免地能够掌握
Inevitable that we would be able
利用原子核内能量的技术
to harness the energy inside the nucleus of atoms
但事实远非如此 认真的科学家认为
But that was far from the case in fact serious scientists,
这个想法是可笑的 就像诺贝尔奖得主罗伯特•米利根
thought the idea was laughable like Nobel laureate Robert
在1928年说
Millikan who in 1928 said there is no
人类不可能接触到原子的能量
likelihood man can ever tap the power of the atom
当我们的煤炭耗尽的时候
The glib supposition of utilizing atomic energy when
利用原子能的轻率的假设是完全不科学的
our coal has run out is a completely unscientific
乌托邦式的梦想 或者就像卢瑟福的想的那样 任何一个
Utopian dream or as Rutherford put it anyone who expects a source
期望从原子的转变中获得能量的人都是做梦
of power from the transformation of these atoms is talking moonshine
他们的悲观情绪都是有理由的
now there was good reason
当贝克雷尔第一次观测到放射性现象时 他认为这是一种类似于
for their pessimism when Becquerel first observed to radioactivity he thought it was a phenomenon similar to
当你把辐射以光的形式照射到一个物体上
phosphorescence That’s when you shine radiation like light onto an object
它会吸收能量 然后重新以不同的频率
And it absorbs that energy and later
辐射出去的磷光现象
Reradiates it in a different part
众所周知铀矿石就是这样的 我就曾亲眼目睹过
of the spectrum now uranium ore was known to do this as I witnessed firsthand. Oh,
是的 X荧光铀矿 这里
yeah X yes fluorescent uranium ore Yeah Here,
它正在吸收紫外线
it’s absorbing UV
并将它再辐射为可见光
light and reradiating it as visible light in
在1896年贝克勒尔做了个实验 他把铀矿
1896 Becquerel performed experiments where he placed uranium ore
放在一些包装胶片上 放置在阳光下
in the sunshine on top of some wrapped up
他发现胶片被曝光了
Photographic film he found that the film was exposed
看起来是因为当铀被阳光刺激时
Seemingly by invisible rays
铀矿石发出了无形的射线
from the uranium ore that penetrated the paper when the uranium was excited by the sunlight
但有一天当他做这个实验时
But one day when he went to do his
巴黎的天气很糟糕
experiment the weather in Paris was lousy so he
因此他把铀和摄影胶卷
put the uranium and the photographic film
放在一个抽屉里 几天后
Inside a drawer and a few days later even
尽管铀没有见到阳光
though the uranium hadn’t seen the Sun
他还是决定冲洗这卷胶卷
He decided to develop the film anyway
他发现
And what he found was
这卷胶卷还是像以前一样被曝光了
that the photographic film had been exposed just as before
尽管铀没有被阳光所激发
Even though the uranium was not excited by sunlight
因此这不仅仅是某种放射物的磷光现象
So this was not a phosphorescence phenomenon some type
因此能量来自于
of radiation and therefore energy was coming out of a rock
未被刺激的岩石
unprovoked
但像岩石这样看似惰性的物体
But how could a seemingly inert object
怎么释放能量呢?
like a rock give off energy
它在哪获得能量
Where is it getting that energy
这是个似乎违反了能量守恒定律的神秘事件
from it was a mystery that seemed to violate the law of conservation of energy?
直到爱因斯坦发表了著名的E=MC²
That is until Einstein published his famous e equals mc-squared
这暗示了辐射的一种能量来源
Which suggested a source of energy for the radiation
也许是原子核的质量
Might be the mass of the nucleus
只要一点点就能产生很大的能量
Just a tiny bit of mass can give you
这个前提足够
a lot of energy and this premise was enough
使科幻作家肆意发挥他们的
for science fiction writers to let their
想象力 像H. G. 威尔
Imaginations run wild like HG Wells who
在1914年出版了《解放全世界》这本书
in 1914 published the book the world set free
包括第一次提到原子弹这个词
Which includes the first mention
他设想了一种铀手榴弹 可以一直持续爆炸
of the word atomic bomb he envisioned a uranium based hand grenade that would continue to explode
但对科学家来讲这是完全脱离现实的
indefinitely but to scientists this was completely detached
正如爱因斯坦在1933年指出 没有
from reality as Einstein in 1933 put it there is not the
丝毫迹象表明核能会可以被获得
slightest indication that nuclear energy will ever be obtainable it would mean
这将意味着原子将会随意分散
that the atom would have to be shattered at will and
事实就是没有人有能力
That’s just the thing people
使原子核
had no ability to make a nucleus do
做任何事 我们观察的都只是
anything. All we were observing was the natural process
放射性衰变的自然过程 一种特定的
of radioactive decay atoms of a particular
不稳定同位素的原子以某种特有的半衰期
Unstable isotope decaying at random with some characteristic half-life
随机衰变 而释放的能量
And the energy given off although immense on
尽管在原子尺度上是巨大的
the scale of an atom is pretty insignificant
但在人类和世界的尺度上是微不足道的
on the scale of people and the world
单个铀原子的裂变释放出的
the fission of a single uranium atom releases
能量比举起一粒厚度只有一张纸的沙子
Twenty times less energy than the amount required to raise a grain
所需要的能量少二十倍
of sand the thickness of a piece of paper
直到1932年 原子核中唯一已知的
Now up until 1932 the only known particle in
粒子就是质子 因此
the nucleus was the proton so if you wanted
如果你想改变一个原子核
to alter a nucleus you could conceivably
你可以想象向它发射一个质子
Fire a proton at it
但由于原子核和质子
But since the nucleus and the
都是带正电的 它们互相排斥
proton are both positively charged they repel
所以你必须以非常高的速度
so you’d have to fire the proton in
和准确性将原子发射进去来使它
with such high speed and accuracy to get it
击中并黏住一个目标
to hit and stick to a target and
而即使你成功了 你仅影响了一个核
Even then if you’re successful you’ve only affected one nucleus
甚至不能举起一粒沙子
Which at best can’t even lift a grain of sand
因此你会明白为什么那些诺贝尔奖得主们
So you can see why the Nobel Prize
说核武器不会产生的
winners were saying nuclear weapons not gon na happen
但后来发现了中子
But then comes the discovery
中子改变了一切
of the neutron and the neutron changes everything
因为作为无电荷的核粒子 它可以
Because as an uncharged nuclear particle it can drift
像直线地 不偏不倚地穿过物质 直到它撞到原子核
Ghostly undeflected through matter until it hits a nucleus
把它变成别的东西 这就引出了一个叫
Transforming it into something else and this leads to the Epiphany
利奥·西拉德的人
of a man named Leo Szilard
西拉德读了《解放全世界》
Now Szilard read the world set free,
所以他已经想象到了
so he’s already imagined a future in
核能被作为武器利用的未来
which nuclear energy is harnessed by weaponry
他还记得正是他在伦敦
And he remembers the exact moment he comes up
过马路的时候想到了这个主意
with this idea as he’s crossing the street in London
他说他突然想到
He says it suddenly occurred to me that if
如果我们能找到一个被
we could find an element which is split by
中子分裂的元素 当它吸收一个中子的时候
neutrons and which would emit two neutrons
会释放出两个中子 那么那样的一个元素
when it absorbed one Neutron then such an element
如果聚集起足够大的质量可以维持一个核链式反应
If assembled in sufficiently large mass could sustain a nuclear chain
换句话说 中子使我们可以随意引发
reaction In other words the neutron Enables us to trigger
核反应 如果这里有一个原子核
nuclear reactions at will and if there’s a
当用这种方法分裂会释放出两个中子
nucleus which when it splits in this way releases
于是这个原子核会引发越来越多裂变
two neutrons it could trigger more and more
裂变成指数增长
Fission’s and an exponentially increasing
拥有这个性质的原子核是
rate the nucleus that has this property is
铀235
uranium-235
实际上通常它每次
In fact on average it releases
分裂时平均释放出两个半中子
two and a half neutrons every time it divides
突然间
Now all of a sudden you
有可能同时分裂无数的原子核
have the possibility of splitting zillions of nuclei
同时释放出难以置信的能量
simultaneously releasing incredible amounts of energy all at once
这就是一个原子弹 如果你想更好地
That’s an atomic bomb now if you want more control
控制能源的释放 就像核电站里一样
over this release of energy as in a nuclear power plant
那么你就需要吸收一些中子
Well, then you have to absorb a few neutrons so
使得一个原子核的裂变
that the fission of one nucleus only
只平均导致另一个原子核的裂变
Causes the fission of one other nucleus on average
然后你就有一个稳定的连锁反应 每一瞬间都会
Then you have a steady chain reaction that emits the same amount
释放相等的能量 而困难的地方在于这就像
of energy each instant the challenge is that this is like
在刀刃上寻找平衡 吸收太多的中子
Balancing on a knife-edge absorb too many neutrons
会使链式反应迅速衰减至停止
and the chain reaction quickly decays to nothing
吸收过少的中子会使反应的速度
absorb too few and the rate of reactions
成指数增加 很快就又会变成核弹爆炸或切尔诺贝利事故
Increases exponentially and soon you’re back to a bomb or Chernobyl so
因此如果不是因为有中性核粒子中子
if not for the existence of the neutron a neutral
能触发反应——相对于较大的原子核中的质子而言
nuclear particle to trigger reactions that occurs
触发了更多的核反应堆 这意味着当一个大原子分裂时
in greater numbers relative to protons in the larger nuclei meaning
它很可能被释放出来
They’re likely to be given off when a large nucleus splits well,
那么也许许多杰出的科学家会怀疑
then maybe as many brilliant scientists suspected
不可能利用核中的能量
It would be impossible to harness the energy in the nucleus
但是事实上
But as it is
在我们的宇宙中 中子是核物理中的英雄或恶棍
in our universe the neutron is the hero or the villain of nuclear physics
嘿 真理元素频道的这一节得到了
Hey this episode of veritasium was supported by viewers
像众筹网站上的你们
like you on patreon and by the
和长期支持audible频道的观众的支持
longest-running supporter of this channel
audible还提供了一个免费的30天系列服务
Audible and audible offers a free 30-day trial
包括一本免费的有声读物给所有看过这个视频的观众
of their service including a free audiobook to everyone who has watched this video
只要登陆audible.com/veritasium
Just go to audible.com slash veritasium
或发送短信给 真理元素 到500 500
or text veritasium to 500 500
你知道的 我们正迎来盛夏
You know we’re coming into summer,
我觉得这是一个看有声读物的好时间
and I think this is a great time to get into audiobooks.
如果你还没有开始看
If you’re not already because
因为有声读物是许多夏季活动的完美伴侣
audiobooks are a perfect companion for tons of summer
比如去公路旅行或徒步旅行
activities like going on road trips or hiking or
或者只是在海滩上闲逛
just hanging out at the beach I Always,
我外出时 总是试图给我的
try to get more stories
生活带来更多的故事
into my life when I’m out
你知道 做我喜欢的活动
you know doing activities that I love
比如骑车上山
like biking up the hill and
而Audible有着世界上最好的
Audible has the greatest selection of audiobooks
精品有声读物
on the planet one book
我想向你们推荐
I would recommend to you
我一直在听的理查德·罗兹的原子弹的制作
that I’ve been listening to the making of the atomic bomb by Richard Rhodes
这是一个限定帐号
This is the definitive Account
精确的细节描述了炸弹是怎样构成的
with such exquisite detail about how the bomb was
科学家如何使它运作
Constructed how all the scientists made it work and really
以及它是如何改变了世界 现在你可以马上下载这本书
how its transformed the world and you can download this book right now
我们登陆audible.com/veritasium
We’re going to audible.com/veritasium or by texting veritasium to 500
或者发送信息给veritasium到500 500
500 and
我最爱audible的是
what I love about audible is that the books
这些书是你保管的 所以你回去可以
are yours to keep so you can go back
任何时候反复地听
and re-listen to them anytime even if
即使你取消了订阅
You cancel your subscription so head
所以登陆audible.com/veritasium或发送短信到500 500
on over to audible.com slash veritasium or text veritasium to 500 500
我想感谢观众对我的支持
I want to thank audible for supporting me,
并且感谢你的观看
and I want to thank you for watching

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视频概述

介绍了原子核的形成和对世界的改变

听录译者

收集自网络

翻译译者

ふうらいぼう

审核员

审核员YX

视频来源

https://www.youtube.com/watch?v=HD3k1hgbUXQ

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