Name: 量子物理學竟然能用來聞味道？！🧪👃 (You Use Quantum Physics to Smell)
Uploaded: 2026-01-24T11:31:43.000Z
Duration: 9 min 24 s

Our nose uses quantum physics to smell, at least according to our best theory of how smell works.

我們的鼻子運用量子物理來聞到氣味，至少這是我們目前對嗅覺作用最好的理論。

Now, how our noses work was always a bit of a mystery to me, but

其實，我的鼻子到底怎麼運作，對我來說一直有點神祕，

I recently learned how they worked and so I thought I'd make a video about it.

但我最近學到了，所以就想說來拍一支影片跟大家分享。

When you sniff odour, molecules get sucked into your nose and they get captured by a layer of mucus and are then taken to a postage stamp sized area in the top of your nasal cavity called the olfactory epithelium.

當你聞到氣味時，氣味分子會被吸進鼻子裡，然後被一層黏液捕捉，接著被帶到鼻腔頂部一個郵票大小的區域，叫做嗅覺上皮。

This contains bundles of neurons containing special receptor sites which detect the molecules and send signals to the brain.

這裡面有許多神經元，帶有特殊的受體位點，用來偵測氣味分子並傳送訊號到大腦。

It has been difficult to know exactly how receptors work because nobody has worked out a way of looking at them while they're in a living nose.

我們一直很難確切知道受體是如何運作的，因為沒有人想出一個方法，可以在活體鼻子裡觀察它們。

You can take them out of a nose and look at them, but

你可以把受體從鼻子裡取出來觀察，但

then they lose their structure when they're not supported by the cell membrane that they sit in.

當它們不再被它們所在的細胞膜支撐時，就會失去結構。

It would be like taking a jellyfish out of the sea which just collapses into a mushroom.

這就像把水母從海裡撈出來，牠就會塌成一朵香菇一樣。

We know that the sensation of smell is caused by odor molecules being caught by the receptor sites, which then causes those neurons to fire.

我們知道，氣味的產生是因為氣味分子被受體位點捕捉，然後引發神經元放電。

But because we can't directly look at the receptors, we have to infer how they work from indirect evidence.

不過因為我們無法直接觀察受體，所以我們得從間接證據來推斷它們的運作方式。

Now, there's two main theories about how smell receptors work, shape and vibration.

現在，關於嗅覺受體如何運作，有兩種主要的理論：形狀理論和振動理論。

The shape theory says that the smell receptors have specific shapes that fit the odour molecules, kind of like a key fitting into a lock.

形狀理論認為，嗅覺受體有特定的形狀，可以和氣味分子契合，就像鑰匙插入鎖孔一樣。

However, this theory doesn't quite work because we know that we don't have one kind of receptor for every type of odor molecule.

不過，這個理論有點說不通，因為我們知道並不是每一種氣味分子都有對應的一種受體。

We have about 300 different kinds of receptors, but we can detect about 10,000 different smells.

我們大約有三百種不同的受體，但卻能分辨出大約一萬種不同的氣味。

So there's something more complicated going on.

The latest theory is that each receptor is built to fit just one section of a molecule.

最新的理論是，每個受體都是為了契合分子中的某個特定部分而設計的。

So any molecule that has that part will have a similar smell.

所以任何帶有那個部分的分子，都會有類似的氣味。

So any molecule that has a sulfur hydrogen bond will smell like rotten eggs.

是以，任何帶有硫氫鍵的分子，都會聞起來像壞掉的雞蛋。

This matches with the evidence because you can get many different shaped molecules that end up having the same smell because they've got a similar molecular group.

這跟證據很吻合，因為很多形狀不同的分子，因為擁有相似的分子基團，最終卻有相同的氣味。

However, this theory can't explain everything.

不過，這個理論無法解釋所有情況。

There are certain molecules that are made of the exact same groups, but

有些分子是由完全相同的基團組成，

are just arranged in a different way, but they smell very different to each other.

但排列方式不同，聞起來卻截然不同。

For example, vanillin, which smells like vanilla, has all the same molecular groups, just in a different order to isovanilin, which has a very nasty, sickly medicinal smell.

例如，聞起來像香草的香蘭素，和異香蘭素擁有相同的分子基團，只是順序不同，異香蘭素聞起來有股非常難聞、病態的藥味。

So there's an alternative theory of smell, the vibration theory.

所以，還有另一種嗅覺理論，就是振動理論。

In the vibration model of smell, the smell receptor can tell the difference between different molecules based on how they vibrate.

在嗅覺的振動模型中，嗅覺受體可以根據分子振動的方式來分辨不同的分子。

Each chemical bond has a certain resonant frequency that it naturally vibrates at.

每個化學鍵都有一個特定的共振頻率，會自然地振動。

Kind of like how an open guitar string always resonates at the same frequency and so always gives you the same pitch.

就像吉他開弦總是會以相同的頻率共振，發出相同的音高一樣。

So different molecules have a different signature set of vibrational frequency, which depends on what atoms they're made of and how they're all connected.

所以，不同的分子會有不同的振動頻率組合，這取決於它們由哪些原子組成以及它們是如何連接的。

In the past, scientists have harnessed this property to figure out the chemical composition of molecules using light in a process called Raman spectroscopy.

過去，科學家們利用這個特性，透過一種稱為拉曼光譜的過程，利用光來判斷分子的化學成分。

When you shine laser light through a bunch of molecules, some of the light's absorbed to make these molecular bonds vibrate, and

當你用雷射光照射一堆分子時，部分光會被吸收，讓這些分子鍵振動，然後

then light with different energy and hence a different frequency is emitted.

會發射出能量不同、頻率也不同的光。

You can then look at the frequencies of this new light, which we see as their color, and

接著，我們就可以觀察這些新光的頻率，也就是我們看到的顏色，

並推算出這些分子是由什麼組成的。

And it's worth mentioning that when it comes to light, each specific color relates to a specific frequency which has a specific energy.

值得一提的是，關於光，每一種特定的顏色都對應著一個特定的頻率，而這個頻率具有特定的能量。

There's a one to one mapping between them.

它們之間是一對一的對應關係。

This has been a great way to detect different kinds of molecule.

這一直是偵測不同種類分子的絕佳方法。

So perhaps our smell receptors are doing something like this.

所以，或許我們的嗅覺受體也在做類似的事情。

But for many years, the vibration theory of smell was not very popular because there's no way our noses can do Raman spectroscopy, as unfortunately, our noses don't emit laser beams.

但很多年來，氣味的振動理論並不怎麼受歡迎，因為我們的鼻子不可能做到拉曼光譜分析，畢竟，我們的鼻子不會發射雷射光束。

And we can't be using natural light because we can smell in the dark.

而且我們也不能使用自然光，因為我們在黑暗中也能聞到氣味。

But there is another method to detect the vibrations of molecules that uses electrons instead of light, which comes from the realm of quantum physics.

但還有另一種偵測分子振動的方法，它用電子取代光，這來自量子物理的領域。

Quantum tunneling is the phenomena where quantum particles, like electrons, can travel to places that normal classical particles can't.

量子穿隧是量子粒子（例如電子）可以去到一般經典粒子無法到達的地方的現象。

They can jump through walls by disappearing from one side and immediately peering on the other.

牠們可以透過從一邊消失，然後立刻出現在另一邊，來穿過牆壁。

This is one of the counterintuitive behaviors of quantum particles and is a consequence of quantum particles behaving as spread out waves in a specific situation.

這是量子粒子一些違反直覺的行為之一，也是量子粒子在特定情況下表現得像擴散的波所造成的結果。

Electron tunneling can actually be used to find the resonant frequencies of molecules.

電子穿隧實際上可以用來找出分子的共振頻率。

If we take two metals and separate them by a small barrier and then apply a voltage to make an electron get pushed to one side.

如果我們取兩塊金屬，用一個小障壁隔開它們，然後施加電壓讓電子被推向一邊。

Normally in classical physics, the electron can't get across this barrier, but

在經典物理學中，電子通常無法穿過這個障壁，但是

if the gap is very small, it can quantum tunnel to the other side.

如果間隙非常小，它就可以量子穿隧到另一邊。

An electron in a metal is a certain energy, and

it can only tunnel to the other side if there's an empty hole which has got the same energy.

而且只有當有相同能量的空穴時，它才能穿隧到另一邊。

But if the hole on the other side is at a lower energy, the electron can't tunnel because there's nowhere for the spare Energy to go.

但如果另一邊的空穴能量較低，電子就無法穿隧，因為多餘的能量無處可去。

But if we introduce a molecule into the gap, something interesting happens.

但如果我們在間隙中引入一個分子，就會發生有趣的事情。

If the energy difference between the electron and the hole is just the same as the energy needed to vibrate one of the resonances of the molecule, then the electron is allowed to tunnel across and it drops its extra energy into vibrating the molecule when it goes across.

如果電子和空穴之間的能量差，正好等於分子振動其中一個共振所需的能量，那麼電子就可以穿隧過去，並且在穿隧時將多餘的能量傳遞給分子使其振動。

Scientists have built machines that use this property to probe molecules.

科學家已經建造了利用這個特性來探測分子的機器。

The technique is called inelastic electron tunneling spectroscopy.

這項技術稱為非彈性電子穿隧光譜學。

You can put in different molecules, change the energy difference between the electron and the hole and see where the electron tunnels, which tells you about the resonances of the molecule and so tells you what it's made from.

你可以放入不同的分子，改變電子和空穴之間的能量差，然後觀察電子穿隧的位置，這會告訴你分子的共振情況，進而得知它的組成。

So perhaps our nose is doing the same thing.

所以，也許我們的鼻子也是做著同樣的事情。

Perhaps our smell receptors are behaving like that metal and the gap, which is waiting for an odour molecule to come in, which allows an electron to pass across the receptor and trigger the nerve.

也許我們的嗅覺受體就像金屬和間隙一樣，等待著氣味分子進入，這會讓電子穿過受體並觸發神經。

To find out, scientists did some very clever experiments.

為了找出答案，科學家做了一些非常巧妙的實驗。

This theory makes a very specific prediction that the odor of a molecule depends on the frequencies it vibrates at.

這個理論做了一個非常具體的預測：分子的氣味取決於它振動的頻率。

So if you could change the frequencies of a molecule, you would also change its smell.

所以，如果你能改變分子的頻率，你也會改變它的氣味。

replaced all of the hydrogen atoms with a heavier form of hydrogen called deuterium, which instead of having one proton in the nucleus, they've got a proton and a neutron.

把所有的氫原子都換成一種較重的氫形式，叫做氘，它的原子核裡有一個質子和一個中子，而不是隻有一個質子。

Deuterium has all the same chemical properties as hydrogen, but is much heavier.

氘和氫有完全相同的化學性質，但重得多。

The scientists got a bunch of the normal molecules and the heavier deuterated molecules and got different subjects to sniff them to see if they could tell the difference.

科學家們拿了一堆普通的分子和較重的氘化分子，讓不同的受試者聞它們，看看他們是否能分辨出差異。

Humans, fruit flies and whitefish, they found strong evidence from these creatures that these two different forms of the molecule actually smells different.

科學家發現，從人類、果蠅和白魚身上，他們得到了強有力的證據，證明這兩種不同形式的分子實際上聞起來不一樣。

This is really cool, because it's really good evidence that our noses use quantum physics to smell the world, which I find utterly amazing.

這真的很酷，因為這有力地證明瞭我們的鼻子利用量子物理來聞到這個世界，這讓我感到非常驚奇。

Quantum physics shouldn't play much of a role in our warm, complicated bodies, so.

量子物理在我們溫暖、複雜的身體裡，應該沒什麼作用，所以。

所以它有作用，這真的很不可思議。

But as successful as the vibration model is, it can't explain everything.

不過，振動模型雖然很成功，但它無法解釋所有事情。

You may have heard of chiral molecules, which are molecules that are made of all the same stuff, but

你可能聽過手性分子，這種分子是由相同的物質組成，但

For example, carvone has a left handed and right handed form, because these are made of the same atoms and bonds, they have all the same vibrations, so will look identical to vibration tests like Raman spectroscopy, inelastic electron tunneling.

例如，香芹酮有左手和右手形式，因為它們由相同的原子和鍵組成，它們有完全相同的振動，所以對於拉曼光譜、非彈性電子穿隧等振動測試來說，它們看起來是相同的。

So according to the vibration theory, they should smell the same, but they don't.

所以根據振動理論，它們應該聞起來一樣，但實際上並非如此。

One form smells like caraway or dill and the other smells like spearmint so what can we conclude from all of this?

一種形式聞起來像葛縷子或蒔蘿，另一種聞起來像留蘭香，那麼我們能從這一切得出什麼結論呢？

It seems like you need both the shape model and the vibration model to explain how we smell.

看來你需要結合形狀模型和振動模型，才能解釋我們的嗅覺是如何運作的。

Perhaps our receptors first check the shape of the molecules and then.

也許我們的受體會先檢查分子的形狀，然後。

And then, if they get past that barrier, they are checked for their resonance vibrations through quantum tunneling.

然後，如果它們通過了這個障礙，就會透過量子穿隧檢查它們的共振振動。

But we won't know exactly how this works until we can figure out a way of directly observing the receptor sites in action.

但我們必須找到一種直接觀察受體位點運作的方式，才能確切知道這是如何運作的。

But isn't it crazy to think that these experiences of smell we have of a flower or coffee or freshly baked bread or a newborn baby, this experience of the world, came to your brain through something as strange as quantum tunneling?

但想想看，我們對花、咖啡、剛烤好的麵包或新生兒的嗅覺體驗，這種對世界的體驗，竟然是透過像量子穿隧這麼奇特的過程傳到你的大腦，是不是很瘋狂？

So quantum physics, which seems for many people to be so strange and abstract, well, it's going on right up your nose.

所以，對許多人來說既奇怪又抽象的量子物理，其實就發生在你的鼻腔裡。

Just like all my other videos, I've made a poster for this one.

就像我其他的影片一樣，這支影片我也做了一張海報。

You can either buy it or get it for free.

你可以選擇購買，或是免費取得。

Check in the description to see where to get those.

到說明欄看看在哪裡可以拿到。

Also, if I've made any mistakes in this video, which does happen, I put that in the description too.

另外，如果這支影片中有任何錯誤，雖然偶爾會發生，我會一併放在說明欄裡。

所以如果你發現任何問題，可以先去那裡看看。

If it's not there, then leave a comment and I'll address that.

如果說明欄裡沒有，那就請留言告訴我，我會處理。

Other than that, I'm going to be making a ton more videos now under the banner of domain of science.

另外，我現在要在 domain of science 這個品牌下製作更多影片。