How scientists are creating real-life invisibility cloaks - Max G. Levy

譯者: Ng Kai Yuan 審譯者: 麗玲 辛

A spy presses a button on their suit and blinks out of sight.

間諜按下西裝上的按鈕， 轉眼間就沒了身影。

A wizard wraps himself in a cloak and disappears limb by limb.

巫師用斗篷包裹自己， 手腳乃至全身逐漸消失。

A star pilot flicks a switch and their ship vanishes into space.

星際飛行員點擊開關， 飛船便匿跡於太空中。

Invisibility is one of the most tantalizing powers in fiction,

「隱形」是虛構小說中 最誘人的力量之一，

spanning all kinds of stories.

橫跨了各類故事。

But could this fantasy ever become a reality?

但這個幻想有朝一日會成真嗎？

Well, invisibility is a relative term.

隱形是一個相對性詞語。

Researchers and engineers working in stealth technology

從事隱形技術的 研究人員和工程師

have developed planes nearly undetectable to radar,

開發了幾乎無法 被雷達偵測到的飛機，

and cloaks that conceal tanks from thermal cameras.

以及能從熱成像攝影機中 隱藏坦克的偽裝。

But these innovations don't make things invisible to the human eye.

但對人眼而言，這些創新 並不會使物體隱形。

Our eyes see by taking in the visible light waves that reflect off objects.

我們的眼睛是透過物體反射的 可見光「看」到該物體。

So to make an object invisible without turning off the lights,

若在不關燈的情況下， 要使一個物體隱形，

our eyes would need to see the light from behind that object,

我們的眼睛需要看見 來自物體後方的光，

rather than the light bouncing off the object itself.

而非物體本身所反射的光線。

And to do that, we need to be able to control these visible light waves.

為了達成這個目的， 我們必須懂得控制可見光。

One way to do this is through reflection.

其中一種做法是透過反射。

This method is predictable,

該方法是可預測的，

but it requires maintaining angles too precise for most moving targets.

但這需要維持精確的角度， 對大部分會移動的目標過於困難。

Researchers can also absorb light with ultra-black surfaces

研究人員也可以使用 覆蓋著吸光奈米管的

covered in light-capturing nanotubes,

超黑表面捕捉光線。

but painting something black doesn’t exactly make it invisible.

但是將物體塗黑 並不能讓它真的隱形。

So instead, many researchers are trying to reroute wavelengths around an object

因此，許多研究者轉而 嘗試引導光波繞過物體，

using refraction.

並利用折射來實現。

Refraction describes how light changes direction

折射描述當光線 穿過不同密度的物質，

when it passes between materials of differing density.

會如何改變其行進方向。

When light passes from a less dense medium into a denser one,

光從密度較低的介質 傳遞到密度較高的介質時，

its path gets slightly bent.

它的路徑會略微彎曲。

Consider how someone’s legs look when you sit at the edge of a pool.

想想當你坐在泳池邊時， 別人的腿看起來是什麼樣子。

Since water is denser than air,

由於水的密度比空氣高，

the light waves reflecting from the water to your eyes speed up and bend.

從水面反射到你眼中的光波 會加速並產生彎折。

In nature, this effect has limits.

事實上，這種效果是有限的。

Even when passing through natural materials

即使是穿透折射率最高的天然材料，

with the highest refractive indexes,

light can only bend so far.

光最多也只能彎曲至此。

But in the lab, we can shatter those limits.

但是在實驗室裡， 我們可以打破這些限制。

In the 1990s, theoretical physicist John Pendry

1990 年代，理論物理學家 約翰·彭德里

was working with a defense lab to create a way to absorb radar signals.

與一個國防實驗室合作， 創造一種吸收雷達信號的方法。

The result was a mesh of carbon fibers so thin and densely woven

研究成果是一張極薄而密集， 由碳纖維組成的網，

that they interacted with light in an entirely different way

而碳纖維與光相互作用的方式 和一般的碳完全不同。

from regular carbon.

This inspired Pendry to try similar tricks with other materials.

這個發現啟發彭德里 對其他材料嘗試類似的伎倆。

By altering them at the microscopic level,

透過在微觀層面進行改造，

Pendry could add tiny microstructures

彭德里得以利用 過去被認為不可能的方式，

capable of capturing and bending light in ways previously thought impossible.

添加能捕捉並 彎曲光線的微小構造。

He called this technology metamaterials and developed his most famous example:

他將這項技術命名為超材料， 並開發了他最著名的例子：

a split ring resonator—

開口諧振環——

a metamaterial structure which allowed him to bend light past the theorized limit.

一種超材料結構，允許光線的彎折 超越理論上的極限。

The discovery of negative refraction

負折射的發現

kicked off the modern wave of invisibility research.

開啟了現代的隱形研究浪潮。

To date, labs have designed metamaterials that can completely steer away microwaves.

至今，實驗室設計的超材料 已經可以完全避開微波。

But a true invisibility cloak would need to bend all wavelengths of visible light

但真正的隱形斗篷需要 彎曲所有波長的可見光，

simultaneously and without distortion,

同時進行且不失真。

and refraction doesn’t treat all wavelengths equally.

而折射不會對所有波長 產生相同的反應，

Consider how refractive materials produce rainbows with varying colors.

想想折射材料如何 產生顏色各異的彩虹。

Despite leading the field, metamaterials aren't the only route toward invisibility.

儘管在該領域處於領先地位， 超材料並非通往隱形的唯一途徑。

One lab was able to create a controlled desert mirage using hot air

有個實驗室能夠創造 受控的沙漠海市蜃樓，

其方法是利用地面上方的熱氣 折射冷空氣周圍的光線，

just above the ground to refract light from the cooler air around it

to create distortions and illusions.

以製造扭曲和幻覺。

Unfortunately, this model only operates at thousands of degrees.

不幸的是，該模型僅能在 數千度的高溫下運行。

Another lab created a unique configuration of glass lenses

另一個實驗室打造了 一種結構獨特的玻璃透鏡，

which can bend the light around an object within a ring-shaped area

它可以在鏡片的圓形區域內 彎曲物體周圍的光。

in the lens.

This lens could be made large enough to obscure an entire person,

這個透鏡的大小足以遮蔽一整個人，

but its effect only works when both the observer and the obscured

但只有當觀察者和被隱蔽對象

stand in the exact right positions.

站在完全正確的位置時才有效。

And attempts using cameras to record environments and project them over a cloak

此外，也有人嘗試 使用攝影機錄製環境，

並將它們投影到披風上，

have been hindered by lag and color distortion.

卻遇到延遲和色彩失真的問題。

These efforts, and many more,

諸如此類的努力，

still have a ways to go towards bringing this magical technology to life.

距離實現這魔法般的科技 還有很長一段旅程。

But if one thing is true about science,

但若有件事可稱作科學的真理，

it’s that the limitations we see today could simply disappear.

那就是今日所見的限制， 終將會不復存在。