What is the rarest color in nature? - Victoria Hwang

1,132,489 views ・ 2022-06-09

TED-Ed


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譯者: Camila Lin 審譯者: Bruce Sung
00:07
Every color you see in front of you can be found in nature.
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你眼前的所有顏色, 都能在大自然中找到。
00:11
Some plant, animal, or mineral bears almost every hue imaginable.
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有些植物、動物、礦物, 含有你能想像到的幾乎所有顏色。
00:15
But which of these colors are you least likely to see in the natural world?
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但在這些顏色之中, 哪一種顏色最難在自然中發現?
00:20
There are two factors that drive the rarity of color in nature:
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自然顏色的稀有度, 主要由兩個因素決定:
00:24
physics and evolution.
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物理和演化。
00:27
Let’s start with physics.
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讓我們先來看看物理學。
00:29
Colors are generated when wavelengths of light interact with objects,
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顏色是光的波長 和物體表面互動的結果。
00:33
and most of the colors you’ve seen outside a screen
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你在螢幕外看見的大多數顏色,
00:36
were produced in one of two ways.
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由兩種方式產生。
00:38
In absorption-based colors,
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就基於吸收而產生的顏色來說,
00:40
certain wavelengths are absorbed by an object, while others are not.
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物體會吸收特定波長的光波, 而反射其他波長的光波。
00:44
The result is a matte final color generated by these leftover light waves.
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這些被反射的光波彼此混合, 產生最終顯示的顏色。
00:49
Most naturally occurring colors fall into this category,
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大多數的自然顏色都是這樣產生,
00:52
including those of many fruits and flowers.
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包括許多水果和花卉的顏色。
00:55
Plants are full of compounds called pigments that absorb light waves
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植物飽含名為「光合色素」的化合物,
用來吸收光線,作為光合作用的一環。
00:58
as part of photosynthesis,
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01:00
the process by which they convert sunlight into energy.
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光合作用能將陽光轉化為能量。
01:03
While different plants have evolved different pigments
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由於不同植物演化出不同的色素,
01:06
that result in different colors,
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所以它們呈現的顏色也不同,
01:08
higher energy wavelengths are more easily absorbed than lower energy ones.
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較高能量的波長, 比較低能量的光更容易被吸收。
01:13
And blue light has some of the highest energy wavelengths
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而在可見光中,
藍光是能量最高的光波之一。
01:15
in the visible spectrum.
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01:17
Numerous pigments have evolved to absorb blue light,
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許多光合色素演化出吸收藍光的功能,
01:20
including chlorophyll, which absorbs blue and red wavelengths
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例如能吸收紅光和藍光的葉綠素,
01:23
to produce nature’s trademark green.
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製造出大自然的標誌性綠色。
01:26
However, green light is still fairly energetic,
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但是,綠光的能量也不低,
01:29
and the most common class of pigments evolved to absorb these wavelengths
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因此最常見的光合色素也都演化出
吸收綠光的功能。
01:33
as well.
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01:34
There are over 1,100 types of carotenoids,
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有超過 1100 種類胡蘿蔔素,
01:38
pigments which absorb high energy blue and green light,
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這是一種能吸收高能量的藍光與綠光,
01:42
while leaving behind the lower energy red and yellow light.
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同時反射低能量的 紅光與黃光的光合色素。
01:46
While carotenoids are present in most green plants,
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雖然幾乎每種植物都含有類胡蘿蔔素,
01:49
they only become visible each fall when chlorophyll gets broken down
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但要到每年秋天,植物為了 儲備過冬能量而分解葉綠素時,
01:53
to save energy for the winter.
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我們才能看見它們的顏色。
01:55
But whether they’re working alone or side by side,
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但無論這些光合色素 是分工合作,或是單打獨鬥,
01:58
these pigments absorb blue light in virtually all plants.
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幾乎所有植物都會吸收藍光。
02:02
Even fruits and flowers that appear blue
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就算是看似藍色的水果或花朵,
02:05
actually have pigments that are red or purple,
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其實也含有紅色或紫色的色素,
02:07
and only truly turn blue under specific chemical conditions.
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並只在特定化學條件下才會變成藍色。
02:12
So, is blue the rarest color in nature?
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所以藍色是自然中最稀有的顏色嗎?
02:16
Not quite.
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還不能下定論。
02:18
Absorption is just one of the two main ways light generates color.
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吸收只是光產生顏色的其中一種方法。
02:23
In the second method, some wavelengths are scattered and amplified—
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第二種方法中, 某些光波被散射、放大,
02:27
overpowering the others to determine an object's final color.
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凌駕於其他光波之上, 決定了物體最終的顏色。
02:31
These structural colors occur
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這些結構色之所以產生,
02:33
because some objects around us are made of microscopic particles
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是因為我們周遭的 某些東西由微粒組成,
02:37
which can form nanostructures that interfere with visible light.
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能產生奈米結構,和可見光相互作用。
02:42
For example, this feather has no blue pigments in it.
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例如,這根羽毛並不含藍色的色素。
02:46
But when light strikes it, the electrons within its nanostructure
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但光照射在羽毛上時, 羽毛奈米結構中的電子
02:50
vibrate at the same frequency as the weight.
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會用和光波相同的頻率震動。
02:53
This makes the particles send out a new wave with the same frequency,
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因此,粒子也會發射相同頻率的新波,
02:57
starting a chain reaction that amplifies and scatters blue light.
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開始一段能放大、 折射藍光的連鎖反應。
03:03
Nanostructures of various shapes and sizes scatter different wavelengths,
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不同形狀和尺寸的奈米結構, 會折射出不同波長,
03:07
but they typically scatter high-energy wavelengths most easily—
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但它們通常最容易折射高能量的光波,
03:11
making blue the most common structural color.
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讓藍光成了最常見的「構造色」。
03:16
Meanwhile, low-energy wavelengths like red are only weakly scattered.
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而紅色這種低能量的光波, 折射力道通常很弱。
03:20
Even when something evolves specific nanostructures
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就算有東西演化出特別的奈米結構,
03:23
that strongly scatter red light
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能折射出強烈的紅光,
03:25
they still resonate with other wavelengths,
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這些結構仍會和其他波長的光共振,
03:27
only appearing red at some angles of illumination and observation.
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只能以某些角度照明、觀察, 才能看見紅色。
03:32
This gives us two contenders for nature’s rarest color:
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這讓我們看見自然界 最稀有顏色的兩個競爭者:
03:36
absorption-based matte blues and structural iridescent reds.
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因吸收混合出的藍色, 以及結構色中的紅色。
03:41
Between these two, structural reds are much rarer.
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以這兩者來說,結構色的紅色更稀有。
03:45
Only a handful of animals and rocks scatter red light
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只有少數動物和石頭能折射出紅光,
03:48
and none of them scatter red light exclusively.
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但沒有一種物體能只折射出紅光。
03:51
But since red and blue are rare in one way and common in another,
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在兩種形成顏色的方式中,紅色 和藍色各是一種稀缺另一種普遍,
03:55
we actually end up seeing both colors quite often.
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因此我們仍能時常看見紅色與藍色。
03:59
So what color is least likely to be generated
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所以,究竟是哪種顏色最難製造,
04:02
in structural and absorption-based forms?
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不管是以結構色還是吸收色而言?
04:06
The answer is violet.
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答案是藍紫色。
04:08
Not to be confused with purple, which is just a combination of red and blue light,
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可別把它誤認成 紅光和藍光混合出的紫色。
04:13
violet occupies a small portion of the visible light spectrum.
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藍紫光也是可見光譜裏的小小一員。
04:17
There are only a few nanostructures precise enough
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只有少數夠精確的納米結構,
04:20
to exclusively scatter violet light.
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才能特別散射出藍紫光。
04:23
And violet wavelengths are even more energetic than blue ones,
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藍紫光的能量比藍光更強,
04:27
making them likely to be absorbed by pigment.
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因此更容易被光合色素吸收。
04:30
So if you ever stumble onto the iridescent violet wings
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所以如果你碰巧看到
紫帝王蝶的藍紫色雙翅,
04:34
of a purple emperor butterfly,
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04:37
take a second to appreciate one of nature’s rarest spectacles.
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就花點時間,欣賞 大自然中最獨特的奇觀吧。
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