The science of friction -- and its surprising impact on our lives | Jennifer Vail

Transcriber: Joseph Geni Reviewer: Camille Martínez

譯者: Pei-Chen Benson Liu 審譯者: Lo Hsien Huang

I have to admit that it's a lot of fun

每當人們問起我做什麼工作，

when people ask me what I do for my job,

要回答這個問題是件趣事。

因為我常說就是拿物品來互相摩擦。

because I tell them I literally rub things together.

This sounds ridiculous,

拿物品來互相摩擦聽起來很荒謬。

just rubbing things together.

But it has a technical name:

不過這件事有個正式名稱：

tribology.

摩擦學。（tribology）

T-r-i-b-o-l-o-g-y,

from the ancient Greek word "tribos,"

這個詞從古希臘文「tribos」衍生而來，

which means "to rub."

意思就是「磨擦」。

It's a funny-sounding word you've probably never heard before,

這個詞聽來也許滑稽又陌生，

but I promise you,

不過我跟各位保證，

discovering it changes your experience with the physical world.

探索這個領域能讓各位 以全新方式感受物質世界。

Tribology has given me amazing projects.

摩擦學也給了我機會 從事一些很棒的計畫，

I've worked on materials that fly, and I've worked on dog food --

我研究過飛行器材料， 也研究過狗食——

a combination that doesn't sound like one person has any business doing

除非從摩擦學的角度看世界，

in the span of just a couple years,

不然這組合一般人實在 很難在幾年內有所接觸。

until you start to view the world through a tribological lens.

And I think you'll be surprised

相信各位稍後會感到非常驚訝，

at how significant a little bit of tribology can be

因為瞭解一點摩擦學就能

in alleviating some very large problems.

減緩一些大難題。

Tribology is the study of friction, wear and lubrication.

摩擦學研究的是摩擦力、 磨損和潤滑等問題。

You have all experienced all three of these things.

這三件事各位一定都有所經歷。

Remember the last time you tried to move a heavy object across the floor,

還記得嘗試挪動地板上的重物時，

and you could just feel something resisting you?

卻感覺受到阻擋嗎？

That would be friction.

那便是摩擦力。

Friction is the force that opposes motion.

摩擦力阻擾運動，

Wear is the loss or transfer of material.

磨損則指物質損失或轉移，

It's the reason you have to replace your favorite shoes,

再中意的鞋子，鞋底終究會消耗殆盡，

because eventually the soles disappear.

而需要汰換，

磨損正是主因。

Lubricants are used to reduce friction and wear.

潤滑減少摩擦力和磨損，

They loosen up those stubborn rusted bolts that just otherwise will not budge.

否則卡死的生鏽螺栓就無法鬆脫、轉動。

But tribology is also defined as the science of interacting surfaces

摩擦學也研究不同表面相對運動時，

in relative motion.

如何相互影響。

So, interacting surfaces in relative motion:

不同表面的相對運動， 有非常多這樣的例子。

there are a lot of those in the world.

As you're sitting there right now, are you wiggling your foot at all

各位坐在這，

會偶爾活動雙腳或改變坐姿嗎？

or maybe shifting around in your seat?

Because guess what? Tribology is happening.

摩擦學可能正起了作用。

Even the smallest shift in your seat

就算只在座位上稍稍挪動，

involves two surfaces moving relative to each other.

也會有兩個表面發生相對運動。

And your tribological interaction for the shift

每個人體驗到的摩擦感受不盡相同。

will be different than the person next to you.

This is because the clothes you're wearing

各位的衣著不同，

change the friction between you and the seat.

與座位間的摩擦力便會有所改變。

If you're wearing silk, it's a little easier to squirm around in the seat

相較於羊毛，穿著絲織品，

在座位上移動會輕鬆一些，

than if you're wearing wool.

因為絲織品磨擦力較小。

That's because the friction is lower for silk.

If you're moving your ankle or wiggling your ankle at all,

各位移動或扭動腳踝時，

did it make a popping sound?

有沒有聽過啪的一聲呢？

You've had that, right?

有過這種事，對吧？

You get up, you move around, and some joint cracks or pops.

起身走動時，關節發出聲音，

Thank you for that sound, tribology.

都是因為摩擦學。

That sound can come from the fluid that lubricates your joints

關節移動時，其中的液體具潤滑效果，

just moving around.

那樣的聲音便是就由此而生，

You're essentially releasing gas bubbles in that fluid.

因為液體中的氣泡受到釋放。

That sound can also come from the tendons simply moving over each other.

也可能是肌腱發生相對運動。

Pretty common in the ankle,

這種情況在腳踝很常見，

so any of my fellow foot-wigglers out there

所以若是時常扭動腳踝，

may suddenly find themselves curious about the tribology of tendons.

你應該會很有興趣，

馬上想瞭解肌腱裡的摩擦學。

But how does one become a tribologist like me?

不過我又是如何成為摩擦學家的呢？

It starts when you're a kid, of course.

這得從我幼年說起。

I was a ballerina growing up.

我自小跳芭蕾舞長大，

I reached the level where I was dancing on my toes,

當時已經在踮著腳尖跳舞，

or "en pointe."

也就是法文的「en pointe」。

Now, when you're dancing en pointe, you're wearing those amazing shoes,

踮著腳尖跳舞時，會穿著漂亮的舞鞋，

but they can be slippery on the stage.

但這樣在舞台上會滑。

The last thing you want to do when you're trying to dance on your toes

這種時候，最可怕莫過於滑倒，

is to slip and fall.

So we had boxes of stuff called rosin.

因此我們會使用松香這個東西，

We would step into the rosin, put a light coating on our shoes.

踩到松香裡，舞鞋上就會有一層薄膜。

Rosin comes from tree sap

松香是樹木的汁液，

and, in its powdered form, makes things less slippery.

製作成粉能止滑。

You learned real fast as a dancer

習舞很快就會知道 在舞鞋上得施多少力。

how much was the right amount to put on your shoes,

because if you didn't put enough on, you were probably going to slip

如果施力不足，

舞鞋與舞台間摩擦力不夠，

due to the low friction between your shoe and the stage.

就有可能滑倒。

Best case scenario,

幸運的話，

you're the clumsy ballerina on stage,

只是在台上看來手腳不協調，

but the worst case scenario would be an injury.

但如果不甚幸運，就會受傷。

Already, I was optimizing and manipulating friction.

我小時候就已經在調整、 操縱摩擦力了。

You see, I was destined to be a tribologist.

看吧，我注定是個摩擦學家。

(Laughter)

（笑聲）

But you were also a junior tribologist.

其實各位也是入門的摩擦學家，

When you used crayons or colored pencils,

使用蠟筆或色鉛筆時，

you knew that the harder you pressed, the darker the color.

大家都知道越使力，顏色就越深。

You also knew this meant you were going to have to sharpen

也知道因為這樣畫，

that crayon or colored pencil more frequently,

磨損得更快，更常需要削筆。

because it was wearing down faster.

Now let's talk about those enticing shiny waxed floors

地板上蠟之後， 人人都想在上面滑來滑去。

that you just had to slide across.

You knew if you put on a pair of socks,

大家都知道如果穿著襪子， 滑起來更為容易。

you were going to get a really good slide across that floor.

Good luck trying to do that barefoot.

赤腳可就沒那麼簡單。

Master manipulators of friction.

如此操縱摩擦力非常高明。

All kids are tribologists.

小孩其實也是磨擦學家。

What about us as adults?

那大人呢？

At some point today, you brushed your teeth.

各位今天一定都刷過牙了，

I hope.

希望如此。

(Laughter)

（笑聲）

This is tribology in action.

這也是摩擦學在作用。

The toothpaste and toothbrush are working to remove or wear

牙刷和牙膏會移除或磨損牙菌斑。

the plaque from your teeth.

For the record, my dad is a dentist.

順道一提，我父親是位牙醫，

Never thought my career was going to circle back to the family business.

我從沒想過自己的職業 會跟父親的職業有所相關。

But one day, we found ourselves speaking the same language

直到有天，我在研究 如何移除牙菌斑時，

when I was tasked with developing a test to investigate plaque removal.

跟父親有了共同話題。

Sounded simple enough,

聽起來很簡單，

until I started to look at it as a tribologist,

但從摩擦學的角度來看，

and then it became incredibly complex.

卻變得複雜無比。

You have hard materials -- those would be your teeth --

刷牙時，嘴裡會有硬組織——

也就是牙齒。

soft materials like your gums, the toothpaste, the toothbrush.

也有軟組織，像是牙齦、牙膏和牙刷。

There's lubrication -- the form of saliva and water --

還有潤滑物，像是口水、清水，

還有刷牙這個動作等等。

the dynamics of the person doing the brushing and more.

I promise if we put diamonds in your toothpaste,

我很確定把鑽石摻在牙膏裡，

you're going to remove that plaque.

一定能清除牙菌斑。

Probably going to remove your teeth as well.

但牙齒可能也無可倖免被磨損，

So there's a fine balance to be had between wearing the plaque away

所以在磨去牙菌斑 和不傷害牙齒和牙齦之間，

and not damaging your teeth and gums.

得有適當的平衡。

We're brushing our teeth because we ate.

我們吃東西，所以才要刷牙。

Eating is another routine thing we all do.

吃東西是另一件尋常不過的事情。

Seems simple enough.

看似簡單，

But it's another field of tribology,

但在摩擦學的領域裡，

and it's not so simple.

卻很複雜。

You have the food, which will break and wear while you're eating,

進食的時候，食物會分解、磨損，

and that food is interacting with your teeth, your tongue,

也會跟牙齒、舌頭、 唾液、喉嚨有所接觸。

your saliva, your throat.

And all of those interactions are going to influence your experience of eating.

所有過程都會影響進食時的感受。

I think you can all recall a moment where you tried something new

各位嘗試新食物時，

and you just found yourself going,

一定有這種經驗：

"Well, it tastes alright.

「味道是還可以，但口感不太行。」

I really don't like that texture."

Tribologists are looking at lubricity, the coefficient of friction,

摩擦學家會研究潤滑和摩擦係數，

as ways to connect mouth feel and texture to what you're experiencing,

讓口感得以與味道相輔相成。

so that if we're changing the formulations of what we're eating and drinking

像是藉著改變飲食成分，

so the sugar content or fat content are different,

讓糖份或脂肪含量有所不同。

how does that change mouth feel?

口感會出現什麼差別？

How do we quantify that?

又要如何量化這個問題呢？

This is what tribologists are looking to solve.

摩擦學家正致力解決此課題。

And while my colleagues were in one corner of this lab

當我的同僚在實驗室一角 研究優格的脂肪含量時，

looking at the fat content of yogurt,

I was in another corner

我在另一邊研究狗食。

studying dog food.

That lab smelled really good, by the way, let me tell you.

我可以跟大家說，實驗室裡很香。

We all brush our teeth on a regular basis.

大家都會定時刷牙，

How many of us brush our pets' teeth?

但有多少人為寵物刷牙呢？

Animals as adults commonly get periodontal disease,

動物跟成人一樣常染上牙周病，

so we really should be brushing their teeth,

所以我們應該幫寵物刷牙。

and more pet owners are starting to do this.

也有越來越多飼主在做這樣的事，

I know my best friend is really great at brushing her cat's teeth, somehow.

我最好的朋友就很擅長幫她的貓刷牙，

Good luck trying to do that with my cat.

我的貓根本不讓我刷。

So what pet food suppliers are trying to do

所以寵物食品製造商嘗試結合 零食和移除牙菌斑的功能。

is incorporate plaque removal in things like treats.

如果各位有養狗，

If you have a dog,

you may have observed that you give a dog a treat,

會發現如果餵狗吃零食，

and it magically seems to disappear after just one bite.

一口就吞了下去，非常神奇。

So the added challenge here is:

困難之處就在於：

How do you remove plaque when you have one bite?

要如何趁這一口移除牙菌斑。

I developed a benchtop test to study this problem,

我設立了一座操縱臺來研究這個問題，

and to do so, I had to mimic the oral system of dogs:

還模擬了狗的口腔：

their teeth, plaque, saliva.

包括牙齒、牙菌斑和唾液。

And I used friction and wear measurements

接著用計算摩擦力和磨損的方式，

to study the effectiveness of that treat on removing plaque.

來研究各種零食是否有效移除牙菌斑。

If you're sitting there right now thinking about the last time

如果各位還是想不起來，

上次幫寵物狗刷牙是什麼時候，

you didn't brush your dog's teeth, you're very welcome.

這個方法對各位會很有用。

But what's the big deal with tribology?

但摩擦學算是什麼大事嗎？

Let me give you one more example.

讓我再舉一個例子，

No matter where you are right now, you got to this location somehow.

各位今天不管從哪來，

都需要動身來到這裡。

Maybe you walked or rode your bike,

也許是走路或騎單車來，

but for most people in this room, you probably came in a car.

但大部分人應該還是開車或坐車。

Just think about all the tribological systems in a car.

想想汽車內部的摩擦系統，

You have your personal interactions with the car,

各位和車輛會有所接觸，

the car's interactions with the road

車輛和路面也是如此。

and everything under the hood and in the drivetrain.

引擎蓋下和動力傳動系統的 每個部分也沒有例外。

Some routine maintenance is directly connected to tribology.

定期保養跟摩擦學就大有關連。

You know how many miles your tires are recommended for using

各位都知道輪胎大概跑多少里程

before you replace them.

才會需要更新。

You regularly check the treads on those tires.

你們也會定期檢查胎紋。

You're actively monitoring the wear of your tires.

這就是在檢查輪胎的磨損程度。

Tribology is the study of wear and friction,

摩擦學研究的是磨損和摩擦力，

and with tires, friction can be the difference between a safe arrival

就輪胎來說，

摩擦力可說是旅途平安的關鍵。

and a car accident.

This is because the friction between your tires and the road

因為輪胎和路面間的摩擦力

will influence your acceleration, your deceleration

會影響加速、減速，還有剎停距離。

and your stopping distance.

As a driver, you instinctively already know how important friction is,

各位開車一定會知道摩擦力有多重要，

because you know that when the roads are wet,

因為知道路面潮濕時，

they're more dangerous because they're slippery.

更容易打滑而危險許多。

This is because the water is reducing the friction

問題出在輪胎與路面間的摩擦力，

between your tires and the road.

因為水的關係降低了。

You may recall that friction is the force that opposes motion,

各位還記得摩擦力會阻擾運動，

so water reducing that force means it's now easier for you to move,

所以水減低摩擦力代表移動更容易，

hence it's more slippery when the roads are wet.

也就是路面潮濕時，更容易打滑。

Something else to consider

還有一件事要考慮進去，

is that overcoming friction takes energy,

克服摩擦力需要能量。

so you're losing energy to friction.

所以摩擦力會消耗能量。

This is one way your tires can influence your fuel efficiency.

這就是為什麼輪胎會影響燃油效率。

And, in fact, did you know that about one-third of the fuel

各位知道其實引擎有三分之一燃料，

that you put into your internal combustion engine vehicle

用來抵抗摩擦力嗎？

will be spent overcoming friction?

One-third.

三分之一。

Tribology research has helped us reduce friction

摩擦學研究可以減低摩擦力，

and therefore increase fuel efficiency and reduce emissions.

而增加燃料效率、減少廢氣排放。

Holmberg and Erdemir have actually done some great studies

霍姆伯格和埃代米爾的 研究結果非常重要，

showing the impact tribology research can have

那便是摩擦學是如何能降少能源消耗。

on reducing our energy consumption.

And they found that, looking over the span of 20 years,

他們發現在 20 年間，

we had the opportunity to reduce

我們也許能讓客用交通工具，

the energy consumption of passenger vehicles

減少百分之六十的能源消耗。

up to 60 percent.

When you think about all the cars in the world,

想想世界上有那麼多車輛，

that's a lot of energy we can save.

省下的能源想必非常可觀。

It's part of the nearly nine percent of our current global energy consumption

這份研究指出摩擦學能為我們省下

相當於當今全球能源 消耗量的百分之九。

that the authors identified tribology can help us save.

That's a significant amount of energy.

如此份量的能源非常龐大，

So when you look at the numbers, tribology can do some amazing things.

看看這些數字便能知道 摩擦學能做出有力的貢獻。

My colleagues have identified up to 20 quads of energy

我的同僚認為光是在美國

便能省下 20 夸特能源。

we can save across the US alone.

To put this in perspective:

具體一點來說，

one quad of energy is roughly equivalent to 180 million barrels of oil,

一夸特能源大約等於 一億八千萬桶石油所產的能量。

and tribology can help us save 20 times that.

摩擦學能幫我們減少 此數值二十倍之多。

This is through new materials, new lubricants,

只需新材質、新潤滑方法、

novel component design,

新零件設計，

doing things like making wind turbines more efficient and reliable.

來讓風葉這類裝置更有效率且更穩定。

This happened just by putting 31 people in a room

這一切只需要一間辦公室的 31 個人

who viewed the world through a tribology lens.

以摩擦學的角度，檢視這個世界。

Imagine the opportunities that will reveal themselves

如果能愈加注意摩擦學，

as more of us start to see tribology all around.

不難想像生活中會出現更多機會。

My favorite projects right now are in aerospace applications.

我現在傾心研究航空方面的應用，

I love reducing wear and friction in these challenging environments.

著迷於在如此苛刻的環境之中，

試著減低磨損和摩擦力。

I can make materials and parts

我製作出的材質和零件

that will reduce the friction in moving components and engines

在各零件和引擎運轉時，

so that they have less force opposing their motion.

能降低摩擦力，

進而減少運轉阻礙。

Less force to move means they require less power,

若運作所需能源減少 也就代表消耗較少能源。

so you can use a smaller actuator,

如此一來，傳動裝置能更小巧、

which would weigh less,

更輕、也更省燃料。

which saves fuel.

I can also help make parts that last longer through lower wear.

我製作出的零件， 因為磨損小而更耐用。

This will reduce material waste

如此能減少浪費材料，

and also means we're manufacturing the parts less frequently,

也就不需要如以往時常要生產，

so we're saving energy in manufacturing.

也省下了生產所需的能源。

I encourage you to start seeing tribology in the world around you

希望各位能發現生活中的摩擦學，

and to think about how you would improve those interacting surfaces you experience.

並思考能如何

讓自己接觸的表面有所改善。

Even the smallest improvements

無論這些改善多麼微小，

really add up.

總會有所幫助。

Tribology may be a funny-sounding word,

摩擦學這個詞也許聽來滑稽，

but it has a huge impact on our world.

但對世界卻有很大的影響。

Thank you.

謝謝。

(Applause)

（掌聲）