Why don't perpetual motion machines ever work? - Netta Schramm

譯者: Szu-Wen Kung 審譯者: Helen Chang

Around 1159 A.D.,

在公元 1159 年左右

a mathematician called Bhaskara the Learned

印度一位名為巴斯卡拉的數學大師

sketched a design for a wheel containing curved reservoirs of mercury.

草擬一個輪子 輪內有曲線凹槽盛裝水銀

He reasoned that as the wheels spun,

他解釋當輪子旋轉時

the mercury would flow to the bottom of each reservoir,

水銀會流向每個凹槽的底部

leaving one side of the wheel perpetually heavier than the other.

這樣會讓輪子的一端永遠比另一端重

The imbalance would keep the wheel turning forever.

此不平衡現象會使輪子不停轉動

Bhaskara's drawing was one of the earliest designs

巴斯卡拉的設計圖

是永動機的最早雛形

for a perpetual motion machine,

a device that can do work indefinitely without any external energy source.

在沒有任何外力協助下 機器能不斷運轉

Imagine a windmill that produced the breeze it needed to keep rotating.

想像風車製造使其不停轉動的微風

Or a lightbulb whose glow provided its own electricity.

電燈泡自給自足發光的電力

These devices have captured many inventors' imaginations

這些裝置激發許多發明家的想像

because they could transform our relationship with energy.

因為這能改變人類與能源的關係

For example, if you could build a perpetual motion machine

例如，若你能創造一個永動機

that included humans as part of its perfectly efficient system,

包含人類作為此完美 節能系統中的一部分

it could sustain life indefinitely.

生命可能因此永續存在

There's just one problem.

但是有一個問題存在

They don't work.

就是這種機器行不通

Ideas for perpetual motion machines

永動機的想法

all violate one or more fundamental laws of thermodynamics,

全都違反超過一項的熱力學基本定律

the branch of physics that describes the relationship

那是物理學的一支

解釋不同能量型態之間的關係

between different forms of energy.

The first law of thermodynamics says that energy can't be created or destroyed.

熱力學第一定律提到 能源無法被創造或毀滅

You can't get out more energy than you put in.

輸出的能量必定不多於輸入的能量

That rules out a useful perpetual motion machine right away

此定律立即排除永動機的運作

because a machine could only ever produce as much energy as it consumed.

因一台機器最多能產生它消耗的能量

There wouldn't be any left over to power a car or charge a phone.

沒有多餘能量啟動車子或給手機充電

But what if you just wanted the machine to keep itself moving?

若只想讓機器不斷自行運轉呢

Inventors have proposed plenty of ideas.

發明家提出許多想法

Several of these have been variations on Bhaskara's over-balanced wheel

其中有幾個是巴斯卡拉 不平衡輪子的變體

with rolling balls or weights on swinging arms.

水銀換成滾動球體或擺動的載重力臂

None of them work.

全起不了作用

The moving parts that make one side of the wheel heavier

移動的部分加重輪子的一端

also shift its center of mass downward below the axle.

也使輪子質量中心下墜低於輪軸

With a low center of mass,

低質量中心

the wheel just swings back and forth like a pendulum,

讓輪子像鐘擺般來回擺動

then stops.

隨後停止

What about a different approach?

如果採取不同的方式呢

In the 17th century, Robert Boyle came up with an idea

17 世紀的愛爾蘭 自然哲學家羅伯·鮑爾

提出一個自給水壺的想法

for a self-watering pot.

He theorized that capillary action,

他解釋毛細管作用

the attraction between liquids and surfaces

即液體與管子表面的吸力

that pulls water through thin tubes,

把水吸進細管裡

might keep the water cycling around the bowl.

或許可讓水在容器循環流動

But if the capillary action is strong enough to overcome gravity

但若毛細管作用大到足以克服引力

and draw the water up,

將水吸引上來

it would also prevent it from falling back into the bowl.

同樣能阻止水注入容器裡

Then there are versions with magnets, like this set of ramps.

另個情況則運用磁鐵 就像這條斜坡

The ball is supposed to be pulled upwards by the magnet at the top,

頂端的磁鐵把球吸上來

fall back down through the hole,

然後球掉進洞裡

and repeat the cycle.

重複循環

This one fails because like the self-watering pot,

這想法也失敗，原因如同自給水壺

the magnet would simply hold the ball at the top.

球就被磁鐵吸附在上面

Even if it somehow did keep moving,

就算球真的循環運動

the magnet's strength would degrade over time

磁力會愈趨減弱

and eventually stop working.

最後停止運作

For each of these machines to keep moving,

想讓這類機器持續運作

they'd have to create some extra energy

則必須製造額外的能量

to nudge the system past its stopping point,

促使整個運作系統超越停止點

打破熱力學的第一個定律

breaking the first law of thermodynamics.

There are ones that seem to keep going,

能量看似持續運作

but in reality, they invariably turn out to be drawing energy

但實際上它們總是

從一些外部來源獲取能量

from some external source.

Even if engineers could somehow design a machine

就算工程師能設計一個機器

that didn't violate the first law of thermodynamics,

不違背熱力學第一定律

it still wouldn't work in the real world because of the second law.

因第二定律這在現實中仍行不通

The second law of thermodynamics

熱力學第二定律

tells us that energy tends to spread out through processes like friction.

說能量往往通過摩擦等過程而散失

Any real machine would have moving parts

任何真實機器都會有移動的部件

or interactions with air or liquid molecules

或與空氣和水分子產生交互作用

that would generate tiny amounts of friction and heat,

這會產生小量的摩擦與熱能

even in a vacuum.

即便在真空狀態也是如此

That heat is energy escaping,

熱能就是能量散逸

and it would keep leeching out,

且持續散出

reducing the energy available to move the system itself

這會降低可供系統運作的能量

until the machine inevitably stopped.

直到機器不可避免地停止

So far, these two laws of thermodynamics

截至目前，這兩項熱力學定律

have stymied every idea for perpetual motion

阻礙與永動機相關的任何想法

and the dreams of perfectly efficient energy generation they imply.

及所蘊含的完美節能美夢

Yet it's hard to conclusively say we'll never discover a perpetual motion machine

是否永遠無法發現永動機則難以定論

because there's still so much we don't understand about the universe.

因人類對宇宙的了解仍極為有限

Perhaps we'll find new exotic forms of matter

也許人類會發現全新的運作法則

that'll force us to revisit the laws of thermodynamics.

迫使我們重新審視熱力學定律

Or maybe there's perpetual motion on tiny quantum scales.

又或許永動運作 存在於渺小的量子尺度

What we can be reasonably sure about is that we'll never stop looking.

唯一能確定的是人類不會停止探索

For now, the one thing that seems truly perpetual is our search.

現在唯一確知的永動

是人類的探索