The 2,400-year search for the atom - Theresa Doud

2400年来对原子的追寻 瑟雷萨 道德

翻译人员: Zack Xue 校对人员: Helen Zhang

What do an ancient Greek philosopher

一位古希腊哲学家

and a 19th century Quaker

一位在19世纪的教会教徒

和诺贝尔奖获得者之间有什么联系呢

have in common with Nobel Prize-winning scientists?

Although they are separated over 2,400 years of history,

虽然他们相隔了2400年

each of them contributed to answering the eternal question:

他们都为了一个永恒的问题提供了答案

what is stuff made of?

那就是 事物由什么组成

It was around 440 BCE that Democritus first proposed

在公元前440年 古希腊哲学家德谟克利特

that everything in the world was made up of tiny particles

第一次提出世上所有的物质都是由 微小的颗粒组成的

surrounded by empty space.

而其周围是空的

And he even speculated that they vary in size and shape

他猜测这些颗粒的大小和形状

depending on the substance they compose.

取决于它们所构成的物质

He called these particles "atomos," Greek for indivisible.

他称这些物质为“atomos”，希腊语意为“不可分割”

His ideas were opposed by the more popular philosophers of his day.

他的想法在当时遭到了其他更著名 的哲学家们的反对

例如 亚里士多德就完全不同意

Aristotle, for instance, disagreed completely,

亚里士多德声称 物质是由4种元素组成的：

stating instead that matter was made of four elements:

土地，风，水和火

earth, wind, water and fire,

and most later scientists followed suit.

当时大多数的科学家也跟随他。

Atoms would remain all but forgotten until 1808,

直到1808年，原子学说一直被人们所忽视

when a Quaker teacher named John Dalton sought to challenge Aristotelian theory.

当一个贵族教会老师 约翰道尔顿开始怀疑 亚里士多德的理论

Whereas Democritus's atomism had been purely theoretical,

然而德谟克利特的原子学说仅仅是理论

Dalton showed that common substances always broke down into the same elements

道尔顿的研究显示常见的物质总是

in the same proportions.

最终能分为相同的元素，以固定的比例。

He concluded that the various compounds

他总结多种化合物

were combinations of atoms of different elements,

是原子和不同的元素的组成物，

each of a particular size and mass

这些组成物每个有特定的大小和质量

that could neither be created nor destroyed.

它们既不能被创造或毁灭。

Though he received many honors for his work,

尽管他的研究获是他收获了很多荣誉，

as a Quaker, Dalton lived modestly until the end of his days.

但是作为一名老师，道尔顿很谦虚地过了一生。

Atomic theory was now accepted by the scientific community,

现在，原子学说被科学界所接受

but the next major advancement

但是下一个重大突破

would not come until nearly a century later

直到近一个世纪以后才来临

with the physicist J.J. Thompson's 1897 discovery of the electron.

是约瑟夫·汤姆孙在1897年发现电子。

In what we might call the chocolate chip cookie model of the atom,

有时候我们也称其为“巧克力饼干”原子模型，

he showed atoms as uniformly packed spheres of positive matter

他的研究显示，原子是由均匀 的正电荷物质所构成的球形，

filled with negatively charged electrons.

而内部是充满了负电荷的电子。

Thompson won a Nobel Prize in 1906 for his electron discovery,

汤姆孙对电子的发现，使他 在1906年获得了诺贝尔奖，

but his model of the atom didn't stick around long.

但是他的原子模型学说并没有持续太久。

This was because he happened to have some pretty smart students,

这是因为他培育了一些聪明的学生，

including a certain Ernest Rutherford,

这其中就包括了欧内斯特·卢瑟福，

who would become known as the father of the nuclear age.

卢瑟福后来被人们称之为原子和物理学之父。

While studying the effects of X-rays on gases,

在研究X射线对气体的反应的时候，

Rutherford decided to investigate atoms more closely

卢瑟福决定对原子进行更加彻底的研究，

by shooting small, positively charged alpha particles at a sheet of gold foil.

他将带正电荷的α微粒射向一层金箔。

Under Thompson's model,

根据汤姆孙的原子模型，

the atom's thinly dispersed positive charge

原子内部所分布的正电荷太轻薄

would not be enough to deflect the particles in any one place.

以至于无法使α微粒在任何位置产生偏斜。

The effect would have been like a bunch of tennis balls

这就像一个网球

punching through a thin paper screen.

冲击一层薄薄的纸。

But while most of the particles did pass through,

但是，当大多数的α微粒都直接穿过了金箔

some bounced right back,

还是有一部分被反射回来，

suggesting that the foil was more like a thick net with a very large mesh.

这个现象证明金箔更像是有大洞的网一样。

Rutherford concluded that atoms consisted largely of empty space

卢瑟福总结为原子内部其实有大量的空间

with just a few electrons,

而只有一小部分为电子，

while most of the mass was concentrated in the center,

然而原子的大部分的质量集中在中心，

which he termed the nucleus.

卢瑟福称之为“原子核”。

The alpha particles passed through the gaps

有些α微粒穿过原子内部的缝隙，

but bounced back from the dense, positively charged nucleus.

但是有些则被带正电荷的原子核所反射回来。

But the atomic theory wasn't complete just yet.

至此，原子学说还并不完整。

In 1913, another of Thompson's students by the name of Niels Bohr

在1913年，另一名汤姆孙的学生，叫尼尔斯·玻尔

expanded on Rutherford's nuclear model.

扩充了卢瑟福的原子核模型。

Drawing on earlier work by Max Planck and Albert Einstein

根据早期马克斯·普朗克和 阿尔伯特·爱因斯坦的研究

he stipulated that electrons orbit the nucleus

玻尔规定电子围绕原子核的轨道

at fixed energies and distances,

是有固定的能量和距离（能级）

able to jump from one level to another, but not to exist in the space between.

电子可以从一个能级跳到另一个能级， 但是不能存在于在两个能级之间。

Bohr's planetary model took center stage,

玻尔的“行星模型”很快被大多数人们所接受，

but soon, it too encountered some complications.

但是不久，这个模型遭到了一些难题。

Experiments had shown that rather than simply being discrete particles,

实验证明，电子并不是简单的游离微粒，

electrons simultaneously behaved like waves,

电子同时也像波浪似的无规则运动，

not being confined to a particular point in space.

而且无法被精确的定位在空间中。

And in formulating his famous uncertainty principle,

维尔纳·海森堡构想了著名的“不确定性原理”，

Werner Heisenberg showed it was impossible to determine

他的研究显示，当电子在运动时

both the exact position and speed of electrons

其精确的速度和位置

as they moved around an atom.

是无法被判断的。

The idea that electrons cannot be pinpointed

其主旨就是电子无法被准确定位，

but exist within a range of possible locations

但是可以确定其可能位置范围，

gave rise to the current quantum model of the atom,

这个理论引发了现在的“量子原子模型”，

a fascinating theory with a whole new set of complexities

这是一个让人产生无限遐想的理论，也更加复杂，

whose implications have yet to be fully grasped.

这个理论至今还正在被深度研究。

Even though our understanding of atoms keeps changing,

尽管我们对原子的理解不停的在改变，

the basic fact of atoms remains,

但是基本的事实没变，

so let's celebrate the triumph of atomic theory

现在我们用烟火来庆祝一下

with some fireworks.

原子理论的巨大成功。

As electrons circling an atom shift between energy levels,

当电子围绕着原子核改变能级的时候，

they absorb or release energy in the form of specific wavelengths of light,

它们通过发出一些特殊的光线获取或丢失能量，

resulting in all the marvelous colors we see.

这就是产生了我们所看到不同的颜色。

And we can imagine Democritus watching from somewhere,

我们可以想象德谟克利特如果看到

satisfied that over two millennia later,

两千年后的原子学说回事多么满意，

he turned out to have been right all along.

历史证明他一路都是正确的。