How do geckos defy gravity? - Eleanor Nelsen

譯者: 盧 紀睿 審譯者: 祖碩(Maddox) 曹

It's midnight and all is still,

在午夜，一切都靜止著

except for the soft skittering of a gecko hunting a spider.

除了安靜地爬行著的壁虎在捕捉蜘蛛

Geckos seem to defy gravity,

壁虎看似無視地心引力

scaling vertical surfaces

爬上垂直的表面

and walking upside down without claws,

可以顛倒著爬行卻不需要爪子

adhesive glues or super-powered spiderwebs.

強力膠水或超強力蜘蛛網

Instead, they take advantage of a simple principle:

相反的是，它們利用了一個簡單的原理：

正負電荷相吸

that positive and negative charges attract.

That attraction binds together compounds, like table salt,

吸引力把化合物結合在一起，就像食鹽

which is made of positively charged sodium ions

由正電的鈉離子

stuck to negatively charged chloride ions.

和負電的氯離子結合在一起而成

But a gecko's feet aren't charged

但是壁虎的腳並不帶電

and neither are the surfaces they're walking on.

它們爬行的表面也不帶電

So, what makes them stick?

那麼是什麼使它們黏在一起呢？

The answer lies in a clever combination of intermolecular forces

答案是分子間力

and stuctural engineering.

與結構工程的巧妙結合

All the elements in the periodic table have a different affinity for electrons.

元素週期表中的所有元素 對電子都有不同的親力

Elements like oxygen and fluorine really, really want electrons,

像氧和氟這樣的元素確實很想要電子

while elements like hydrogen and lithium don't attract them as strongly.

氫或鋰這樣的元素卻沒有那麼強的吸引力

An atom's relative greed for electrons is called its electronegativity.

一個原子對於電子的相對需求 叫做它的負電性

Electrons are moving around all the time

電子不停地在運動

and can easily relocate to wherever they're wanted most.

它們可以在最想停留的地方隨時定位

So when there are atoms with different electronegativities in the same molecule,

所以在一個分子中有負電性不同的原子時

the molecules cloud of electrons

被電子包圍的分子們

gets pulled towards the more electronegative atom.

會被拉向最帶負電的原子

That creates a thin spot in the electron cloud

這樣就產生了一個在電子雲中的小點

where positive charge from the atomic nuclei shines through,

來自原子核的正電穿過這個點

as well as a negatively charged lump of electrons somewhere else.

帶負電的電子們也在別的地方聚集

So the molecule itself isn't charged,

這個分子本身並不帶電

but it does have positively and negatively charged patches.

但是它確實有帶正電和負電的區域

These patchy charges can attract neighboring molecules to each other.

這些區域性電荷會吸引周圍的分子

They'll line up so that the positive spots on one

它們會排成一條線 正電區域接著負電區域

are next to the negative spots on the other.

如此一個接一個

There doesn't even have to be a strongly electronegative atom

甚至根本不需要有很強負電的原子

to create these attractive forces.

去創造這些吸引力

Electrons are always on the move,

電子在不停地運動

and sometimes they pile up temporarily in one spot.

有些時候它們在一個點堆積

That flicker of charge is enough to attract molecules to each other.

那一閃的電荷足以讓分子互相吸引

Such interactions between uncharged molecules

未帶電分子的這些相互運動

are called van der Waals forces.

叫做範德華力

They're not as strong as the interactions between charged particles,

它並不像帶電分子間的力那麼強

but if you have enough of them, they can really add up.

但是如果有足夠的量，它們也可以堆積成可觀的力

That's the gecko's secret.

這就是壁虎的秘密

Gecko toes are padded with flexible ridges.

壁虎的腳趾上有易變形的隆起

Those ridges are covered in tiny hair-like structures,

這些隆起表面有頭髮般的細小結構

much thinner than human hair, called setae.

比人類的頭髮細得多，叫做剛毛(setae)

And each of the setae is covered in even tinier bristles called spatulae.

剛毛甚至被小的多的叫做 匙突(spatulae)的結構覆蓋

Their tiny spatula-like shape is perfect for what the gecko needs them to do:

這些匙突型結構完美地承擔了 壁虎要求它們的工作

stick and release on command.

在命令下黏住和釋放

When the gecko unfurls its flexible toes onto the ceiling,

當壁虎在天花板上展開它的可形變腳趾

the spatulae hit at the perfect angle for the van der Waals force to engage.

匙突會形成恰好的腳讓範德華力產生

The spatulae flatten,

匙突變平

creating lots of surface area for their positively

形成很多平面使正電和負電區

and negatively charged patches to find complimentary patches on the ceiling.

在天花板上找到相應的帶電區域

Each spatula only contributes a minuscule amount of that van der Waals stickiness.

每個匙突都貢獻很少量的範德華力

But a gecko has about two billion of them,

但是一個壁虎有二十億的匙突

creating enough combined force to support its weight.

產生足夠的力去支持它的體重

In fact, the whole gecko could dangle from a single one of its toes.

事實上壁虎可以用一根 腳趾把自己吊起來

That super stickiness can be broken, though,

這些強大的力會消失

by changing the angle just a little bit.

如果改變一點點的角度

So, the gecko can peel its foot back off,

所以壁虎可以抬起它的腳

scurrying towards a meal or away from a predator.

衝向一個獵物，或者逃離捕食者

This strategy, using a forest of specially shaped bristles

這個用樹林般特殊突起

to maximize the van der Waals forces between ordinary molecules

在兩個普通分子間去使 範德華力最大化的方法

has inspired man-made materials

啟發了很多人造材料

designed to imitate the gecko's amazing adhesive ability.

模仿壁虎的強大的吸引能力

Artificial versions aren't as strong as gecko toes quite yet,

人造版本尚未像壁虎的那樣的強力

but they're good enough to allow a full-grown man

但是他們已經足夠強到讓一個成年人

to climb 25 feet up a glass wall.

去爬一個25英尺高的玻璃牆

In fact, our gecko's prey is also using van der Waals forces

事實上壁虎的獵物也在使用範德華力

to stick to the ceiling.

去黏在天花板上

So, the gecko peels up its toes and the chase is back on.

那麼，壁虎會撒開腳，衝向它