沃特福德球场: 沃特福德vs南安普顿

2013年經濟學人 愛因斯坦和汽車電池

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沃特福德vs南安普顿 www.siuceg.com.cn Science and technology

科學技術

Einstein and car batteries

愛因斯坦和汽車電池

A spark of genius

天才的靈光

Without the magic of relativity , a car's starter motor would not turn

要不是相對論的魔力,汽車的發動馬達就轉不起來

ALBERT EINSTEIN never learned to drive.

阿爾伯特.愛因斯坦從沒去學開車。

He thought it too complicated and in any case he preferred walking. What he did not know—indeed, what no one knew until now—is that most cars would not work without the intervention1 of one of his most famous discoveries, the special theory of relativity.

他覺得開車太復雜,再者,他更喜歡走路。而他不知道的—也是直到現在人們才知道的是—沒有他的偉大發現之一,即狹義相對論,大多數汽車不可能發動起來。

Special relativity deals with physical extremes.

狹義相對論同物理極限相關。

It governs the behaviour of subatomic particles zipping around powerful accelerators at close to the speed of light and its equations foresaw the conversion2 of mass into energy in nuclear bombs.

該理論掌握了亞原子粒子在強大的加速器的作用下可以達到接近光速的速度這一表現行為。相對論的公式也預見了核彈中質能轉換的現象。

A paper in Physical Review Letters, however, reports a more prosaic3 application.

然而,一篇發表在物理評論快報上的文章,講述了狹義相對論更為一般的應用。

According to the calculations of Pekka Pyykko of the University of Helsinki and his colleagues, the familiar lead-acid battery that sits under a car's bonnet4 and provides the oomph to get the engine turning owes its ability to do so to special relativity.

根據赫爾辛基大學的Pekka Pyykko和他同事們的計算,我們所熟悉的在汽車發動機罩下,給汽車引擎發動提供能量的鉛酸電池,它之所以有這樣的能力都歸功于狹義相對論。

Relative values

相對的價值

The lead-acid battery is one of the triumphs of 19th-century technology.

鉛酸電池是19世紀技術發展的產物之一。

It was invented in 1860 and is still going strong.

它于1860年發明,迄今為止仍然具有很強的實用性。

Superficially, its mechanism5 is well understood. Indeed, it is the stuff of high-school chemistry books.

表面上,其機制為人熟知這些都是高中化學課本上的東西

But Dr Pyykko realised that there was a problem.

但Pyykko博士發覺了哪里不對勁。

In his view, when you dug deeply enough into the battery's physical chemistry, that chemistry did not explain how it worked.

在他看來,越是深入研究電池的物理化學特性,這些化學特性反而越不能解釋電池到底是怎么工作的。

A lead-acid battery is a collection of cells, each of which contains two electrodes immersed in a strong solution of sulphuric acid.

鉛酸電池是電池單元構成的集合,其中每個電池都有兩個電極,浸泡在硫酸溶液的電解液里。

One of the electrodes is composed of metallic6 lead, the other of porous7 lead dioxide.

金屬鉛充當一處電極,另一處電極是多孔二氧化鉛。

In the parlance9 of chemists, metallic lead is electropositive.

化學家認為,金屬鉛是電正性物質。

This means that when it reacts with the acid, it tends to lose some of its electrons.

這表明,當鉛和酸發生反應時,它很可能失去一些電子。

Lead dioxide, on the other hand, is highly electronegative, preferring to absorb electrons in chemical reactions.

而另一方面,二氧化鉛是電負性物質,在化學反應中更喜歡吸收電子。

If a conductive wire is run between the two, electrons released by the lead will run through it towards the lead dioxide, generating an electrical current as they do so.

如果把一根導電金屬絲放在金屬鉛和二氧化鉛之間,鉛釋放的電子會經金屬絲傳遞到二氧化鉛,這個過程會產生電流。

The bigger the difference in the electropositivity and electronegativity of the materials that make up a battery's electrodes, the bigger the voltage it can deliver.

組成電池兩級的物質的正負電荷差越大,他們發生化學反應時產生的電伏數越大。

In the case of lead and lead dioxide, this potential difference is just over two volts10 per cell.

以鉛和二氧化鉛為例的電池,每節電池的電位差可產生2伏電壓。

That much has been known since the lead-acid battery was invented.

自鉛酸電池發明以來,上述的理論就已為人熟知。

However, although the properties of these basic chemical reactions have been measured and understood to the nth degree, no one has been able to show from first principles exactly why lead and lead dioxide tend to be so electropositive and electronegative.

然而,盡管很大程度上我們都掌握和了解這些基礎化學反應,卻沒有人能夠真正說明最根本的原理—為什么鉛和二氧化鉛帶有這般的電正性和電負性呢?

This is a particular mystery because tin, which shares many of the features of lead, makes lousy batteries.

這一點顯得頗為神秘,因為和鉛特性差不大多的錫,無法用來做電池。

Metallic tin is not electropositive enough compared with the electronegativity of its oxide8 to deliver a useful potential difference.

比起鉛來,金屬錫的電正性沒有二氧化錫的電負性強,所以無法產生可用的電位差。

This is partly explained because the bigger an atom is, the more weakly its outer electrons are bound to it and hence the further those electrons are from the nucleus11.

原子越大,其外層電子受原子束縛力越弱,這是解釋鉛和錫兩者差別的一部分原因。

In all groups of chemically similar elements the heaviest are the most electropositive.

在化學性質相似的同族元素中,質量越重帶的正電越強。

However, this is not enough to account for the difference between lead and tin.

然而這依然不能充分說明鉛和錫的差別。

To put it bluntly, classical chemical theory predicts that cars should not start in the morning.

直截了當地說, 古典化學理論預言了早上要離家上班汽車是發不動的。

Which is where Einstein comes in.

那愛因斯坦怎么被扯進來了,

For, according to Dr Pyykko's calculations, relativity explains why tin batteries do not work, but lead ones do.

根據Pyykko博士的計算,相對論解釋了為什么鉛可以用來做電池,而錫不可以。

His chain of reasoning goes like this.

他一連串的理由是這樣解釋的。

Lead, being heavier than tin.

鉛比錫重,核子里的質子數更多。

That means its nucleus has a stronger positive charge and that, in turn, means the electrons orbiting the nucleus are more attracted to it and travel faster, at roughly 60% of the speed of light, compared with 35% for the electrons orbiting a tin atom.

這表明原子核的正電更強,同理表明更容易吸引繞著原子核的電子,電子傳播的速度也更快,其速度是光速的60%,相比之下,繞著錫原子的電子速度只能達到光速的35%。

As the one Einsteinian equation everybody can quote, E=mc2, predicts, the kinetic12 energy of this extra velocity13 makes lead's electrons more massive than tin's—and heavy electrons tend to fall in and circle the nucleus in more tightly bound orbitals.

人人都會引用的愛因斯坦相對論公式:E=mc2,公式表明這一額外速度即更高的能量產生的動能使得鉛的電子比錫的更重不斷增加的質量—而重的電子往往會下落,圍著結合更緊密的原子核軌道繞行。

That has the effect of making metallic lead less electropositive than classical theory indicates it should be—which would tend to make the battery worse.

產生的結果是,金屬鉛的電正性沒有古典化學理論認為的那么強看起來似乎鉛不適合用來做電池。

But this tendency is more than counterbalanced by an increase in the electronegativity of lead dioxide.

但是, 二氧化鉛電負性的增加不但全部抵消了這個趨勢還有剩余。

In this compound, the tightly bound orbitals act like wells into which free electrons can fall, allowing the material to capture them more easily. That makes lead dioxide much more electronegative than classical theory would predict.

在這個混合物里,結合緊密的軌道就像一口井,自由電子落入其中,使得物質更容易捕獲電子。二氧化鉛的電負性其實比古典化學理論認為的要更強。

And so it turned out.

然后他們得出了結論。

Dr Pyykko and his colleagues made two versions of a computer model of how lead-acid batteries work.

Pyykko博士和他的同事們作了兩個版本的電腦模型,來觀察鉛酸電池是怎么工作的。

One incorporated their newly hypothesised relativistic effects while the other did not.

其中一個模型結合使用了相對論效應的新假設,另一個沒有用。

The relativistic simulations predicted the voltages measured in real lead-acid batteries with great precision.

相對論模擬模型預測的鉛酸電池產生的電壓相當精確。

When relativity was excluded, roughly 80% of that voltage disappeared.

而那個不用相對論的模型大約80%的電伏都沒有計算到。

That is an extraordinary finding, and it prompts the question of whether previously14 unsuspected battery materials might be lurking15 at the heavier end of the periodic table.

這是個非同凡響的發現,這個發現也提出了一個問題。是否還有以前沒想到的,潛伏在元素周期表末端的電池材料?

Ironically, today's most fashionable battery material, lithium, is the third-lightest element in that table—and therefore one for which no such relativistic effects can be expected.

諷刺的是,現在最時髦的電池材料,鋰,是周期表中第三輕的元素—如果用相對論效應是料不到它可以用來做電池。

And lead is about as heavy as it gets before elements become routinely radioactive and thus inappropriate for all but specialised applications.

鉛是周期表中放射性元素之前最重的元素,因此除了用于專門應用外不適用于他處。

Still, the search for better batteries is an endless one, and Dr Pyykko's discovery might prompt some new thinking about what is possible in this and other areas of heavy-element chemistry.

而有關更好的電池材料的研究是沒有止境的,Pyykko博士的發現也許給我們提供了一些新的思考方向—化學重金屬在電池和其他地方還有什么作為?

詞語解釋

1.relativity n.相對性;相對論

They teach the relativity of all ethical16 ideas.

他們宣揚一切道德觀念的相對性。

2.intervention n.介入;干預

His untimely intervention annoyed me.

他那不合時宜的干涉讓我生氣。

3.particle n.顆粒;微粒;極小量

We can see the dust particles floating in the sunlight clearly.

我們可以很清楚地看到陽光下的灰塵顆粒。

4.equation n.相等;均衡

I can't make this equation come out.

我不會解這個方程式。

5.prosaic a.單調乏味的;散文的

It was a prosaic description of the scene.

這是對場景沒有想象力的一個描述。


點擊收聽單詞發音收聽單詞發音  

1 intervention e5sxZ     
n.介入,干涉,干預
參考例句:
  • The government's intervention in this dispute will not help.政府對這場爭論的干預不會起作用。
  • Many people felt he would be hostile to the idea of foreign intervention.許多人覺得他會反對外來干預。
2 conversion UZPyI     
n.轉化,轉換,轉變
參考例句:
  • He underwent quite a conversion.他徹底變了。
  • Waste conversion is a part of the production process.廢物處理是生產過程的一個組成部分。
3 prosaic i0szo     
adj.單調的,無趣的
參考例句:
  • The truth is more prosaic.真相更加乏味。
  • It was a prosaic description of the scene.這是對場景沒有想象力的一個描述。
4 bonnet AtSzQ     
n.無邊女帽;童帽
參考例句:
  • The baby's bonnet keeps the sun out of her eyes.嬰孩的帽子遮住陽光,使之不刺眼。
  • She wore a faded black bonnet garnished with faded artificial flowers.她戴著一頂褪了色的黑色無邊帽,帽上綴著褪了色的假花。
5 mechanism zCWxr     
n.機械裝置;機構,結構
參考例句:
  • The bones and muscles are parts of the mechanism of the body.骨骼和肌肉是人體的組成部件。
  • The mechanism of the machine is very complicated.這臺機器的結構是非常復雜的。
6 metallic LCuxO     
adj.金屬的;金屬制的;含金屬的;產金屬的;像金屬的
參考例句:
  • A sharp metallic note coming from the outside frightened me.外面傳來尖銳鏗鏘的聲音嚇了我一跳。
  • He picked up a metallic ring last night.昨夜他撿了一個金屬戒指。
7 porous 91szq     
adj.可滲透的,多孔的
參考例句:
  • He added sand to the soil to make it more porous.他往土里摻沙子以提高滲水性能。
  • The shell has to be slightly porous to enable oxygen to pass in.外殼不得不有些細小的孔以便能使氧氣通過。
8 oxide K4dz8     
n.氧化物
參考例句:
  • Oxide is usually seen in our daily life.在我們的日常生活中氧化物很常見。
  • How can you get rid of this oxide coating?你們該怎樣除去這些氧化皮?
9 parlance VAbyp     
n.說法;語調
參考例句:
  • The term "meta directory" came into industry parlance two years ago.兩年前,商業界開始用“元目錄”這個術語。
  • The phrase is common diplomatic parlance for spying.這種說法是指代間諜行為的常用外交辭令。
10 volts 98e8d837b26722c4cf6887fd4ebf60e8     
n.(電壓單位)伏特( volt的名詞復數 )
參考例句:
  • The floating potential, Vf is usually only a few volts below ground. 浮置電勢Vf通常只低于接地電位幾伏。 來自辭典例句
  • If gamma particles are present, potential differences of several thousand volts can be generated. 如果存在γ粒子,可能產生幾千伏的電位差。 來自辭典例句
11 nucleus avSyg     
n.核,核心,原子核
參考例句:
  • These young people formed the nucleus of the club.這些年輕人成了俱樂部的核心。
  • These councils would form the nucleus of a future regime.這些委員會將成為一個未來政權的核心。
12 kinetic p2Fxs     
adj.運動的;動力學的
參考例句:
  • There exist many sources of energy both potential and kinetic.存在著許多勢能和動能的能源。
  • The kinetic theory of gases is the best known example.氣體動力學理論就是最有名的例子。
13 velocity rLYzx     
n.速度,速率
參考例句:
  • Einstein's theory links energy with mass and velocity of light.愛因斯坦的理論把能量同質量和光速聯系起來。
  • The velocity of light is about 300000 kilometres per second.光速約為每秒300000公里。
14 previously bkzzzC     
adv.以前,先前(地)
參考例句:
  • The bicycle tyre blew out at a previously damaged point.自行車胎在以前損壞過的地方又爆開了。
  • Let me digress for a moment and explain what had happened previously.讓我岔開一會兒,解釋原先發生了什么。
15 lurking 332fb85b4d0f64d0e0d1ef0d34ebcbe7     
潛在
參考例句:
  • Why are you lurking around outside my house? 你在我房子外面鬼鬼祟祟的,想干什么?
  • There is a suspicious man lurking in the shadows. 有一可疑的人躲在陰暗中。 來自《現代英漢綜合大詞典》
16 ethical diIz4     
adj.倫理的,道德的,合乎道德的
參考例句:
  • It is necessary to get the youth to have a high ethical concept.必須使青年具有高度的道德觀念。
  • It was a debate which aroused fervent ethical arguments.那是一場引發強烈的倫理道德爭論的辯論。
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