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

翻译人员: Yuan Shen 校对人员: Jinnie Sun

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

一名间谍按下西装上的一个按钮， 一眨眼就消失不见。

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

一名巫师身披斗篷， 身体的各个部分渐次消失。

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

星际飞行员一按开关， 他们的飞船就会隐没在太空中。

Invisibility is one of the most tantalizing powers in fiction,

隐身是小说中最令人着迷的力量之一，

spanning all kinds of stories.

出现在各种故事里。

But could this fantasy ever become a reality?

但这种幻想能否有朝一日成为现实？

Well, invisibility is a relative term.

实际上，隐身是一个相对的术语。

Researchers and engineers working in stealth technology

隐身技术的研究人员和工程师

have developed planes nearly undetectable to radar,

已经开发出几乎无法 被雷达探测到的飞机，

and cloaks that conceal tanks from thermal cameras.

并使坦克在热成像摄像机的 监控下瞒天过海。

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

但是这些创新并不能 让物体肉眼不可见。

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

我们的眼睛通过吸收物体反射的 可见光波来看见各种物体。

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

因此要在不关灯的情况下 使物体不可见，

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

我们的眼睛需要看到 该物体背后的光线，

rather than the light bouncing off the object itself.

而不是从物体本身反射的光线。

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

要达到这种效果，我们需要 控制这些可见光波。

One way to do this is through reflection.

其中一种方法是通过反射。

This method is predictable,

这种方法是可以预测的，

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

但对于大多数移动目标来说， 它们对保持角度的精确性要求太高。

Researchers can also absorb light with ultra-black surfaces

研究人员也可以通过 覆盖捕光纳米管的超黑色表层

covered in light-capturing nanotubes,

来吸收光线，

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

但是把外皮涂成黑色 并不意味着人们就看不见这个物体。

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

既然此路不通，许多研究人员就开始 尝试通过折射来改变

using refraction.

物体周围的波长线路。

Refraction describes how light changes direction

折射描述的是光在穿过

when it passes between materials of differing density.

不同密度的材料时如何改变方向。

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

当光线从密度较低的介质 进入密度较高的介质时，

its path gets slightly bent.

其路径有些许弯曲。

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

想象一下当你坐在泳池边上时 看别人的双腿是什么样子。

Since water is denser than air,

由于水比空气密度更大，

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

从水中反射到眼睛的光波 会加速并拐弯。

In nature, this effect has limits.

在自然界中， 这种折射的角度是有限的。

Even when passing through natural materials

即使是穿过自然界中

with the highest refractive indexes,

折射率最高的材料，

light can only bend so far.

光线也只能改变一定的方向。

But in the lab, we can shatter those limits.

但是在实验室里， 我们可以打破这些限制。

In the 1990s, theoretical physicist John Pendry

20 世纪 90 年代， 理论物理学家约翰·彭德里

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

与国防实验室合作研究 如何吸收雷达信号。

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

研究成果表明碳纤维网格可以胜任， 这种物质十分纤薄，密度很高，

that they interacted with light in an entirely different way

以至于它们与光相互作用的方式

from regular carbon.

与普通碳纤维完全不同。

This inspired Pendry to try similar tricks with other materials.

这促使彭德里尝试用其他材料 来达到同样的效果。

By altering them at the microscopic level,

通过微观层面的改造，

Pendry could add tiny microstructures

彭德里成功加入了极小的微观结构，

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

以从前无法想象的方式 捕获和弯曲光线。

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

他将这项技术称为超材料， 并由此研究出他最著名的案例：

a split ring resonator—

开口谐振环——

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

一种能够将光线弯曲 超出理论极限的超材料结构。

The discovery of negative refraction

负折射的发现

kicked off the modern wave of invisibility research.

开启了现代隐身技术的研究浪潮。

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

迄今为止，实验室已经设计出 可以完全避开微波的超材料。

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

但是真正的隐身斗篷需要 在弯曲所有可见光波长的同时

simultaneously and without distortion,

保证不失真，

and refraction doesn’t treat all wavelengths equally.

另外折射也不能对所有波长一视同仁。

Consider how refractive materials produce rainbows with varying colors.

想想折射材料是如何产生 五颜六色的彩虹的。

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

即便是该研究领域的前沿技术， 超材料也并非隐身的唯一途径。

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

有一个实验室已经能够利用 靠近地面的热空气

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

折射来自周围较冷空气的光线， 从而产生失真和幻觉，

to create distortions and illusions.

人为制造出海市蜃楼的幻象。

Unfortunately, this model only operates at thousands of degrees.

不过不幸的是，该模型只能 在上千摄氏度的温度下运行。

Another lab created a unique configuration of glass lenses

另一个实验室发现通过 以一种独特的方式摆放玻璃透镜

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

可以在镜头之间的环形区域内 弯曲物体周围的光线。

in the lens.

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

这种透镜可以做得很大， 大到足以遮住整个人体，

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

但只有当观察者和隐身者 都站在完全正确的位置时，

stand in the exact right positions.

光线弯曲才会起效。

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

另外，使用摄像机记录环境 并将其投射到斗篷上时，

have been hindered by lag and color distortion.

延迟和色彩失真也是需要解决的问题。

These efforts, and many more,

要将这项神奇的技术变为现实，

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

我们还需继续努力， 还有很长的路要走。

But if one thing is true about science,

但如果要说科学有什么绝对的真理，

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

那就是我们今天看到的局限性 有一天都会消失。