The hidden network that makes the internet possible - Sajan Saini

翻译人员: Carol Wang 校对人员: Ruilin Yao

In 2012,

在2012年，

a team of Japanese and Danish researchers set a world record,

由日本和丹麦研究人员组成的小组 创下了一项世界记录，

transmitting 1 petabit of data—

在一根50千米的电缆上

that’s 10,000 hours of high-def video—

传输 1 Pbit 的数据用时只有1秒——

over a fifty-kilometer cable, in a second.

这相当于一万小时的高清视频。

This wasn’t just any cable.

这可不是普通电缆。

It was a souped-up version of fiber optics—

这是一种增强型光纤——

the hidden network that links our planet

组成了连接我们的星球、

and makes the internet possible.

让互联网成为可能的隐形网络。

For decades,

几十年来，

long-distance communications between cities and countries

城市或国家间的长距离沟通

were carried by electrical signals,

都由经铜线传导的

in wires made of copper.

电信号承载。

This was slow and inefficient,

这种方式慢而低效，

with metal wires limiting data rates and power lost as wasted heat.

金属线限制了数据传输速率， 而且电线发热造成功率损耗。

But in the late 20th century,

但在20世纪晚期，

engineers mastered a far superior method of transmission.

工程师掌握了一种更好的传输方式。

Instead of metal,

不再使用金属导线，

glass can be carefully melted and drawn into flexible fiber strands,

而是将玻璃精心融化后 拉成柔韧的纤维，

hundreds of kilometers long and no thicker than human hair.

纤维可长至几百公里， 和人的头发一样细。

And instead of electricity,

纤维不再传递电信号，

these strands carry pulses of light, representing digital data.

而是传递代表数字信号的光脉冲。

But how does light travel within glass, rather than just pass through it?

但光如何在玻璃纤维中传导 而不会穿出去呢？

The trick lies in a phenomenon known as total internal reflection.

秘密就在于光全内反射现象。

Since Isaac Newton’s time,

自艾萨克·牛顿时代以来，

lensmakers and scientists have known that light bends

眼镜制造商和科学家们已经知道，

when it passes between air and materials like water or glass.

光穿过空气和其他介质 如水或玻璃的交界时产生折射。

When a ray of light inside glass hits its surface at a steep angle,

当一束穿过玻璃的光 以很陡的角度抵达玻璃表面时，

it refracts, or bends as it exits into air.

它会发生折射， 即弯折后进入空气中。

But if the ray travels at a shallow angle,

但如果光束角度很小时，

it’ll bend so far that it stays trapped,

它会产生反射并留在玻璃中，

bouncing along inside the glass.

在琉璃中来回反弹。

Under the right condition,

在特定条件下，

something normally transparent to light can instead hide it from the world.

透光的东西就能把光藏在其内， 不会让光穿透出来。

Compared to electricity or radio,

与电信号或无线信号相比，

fiber optic signals barely degrade over great distances—

光纤信号在长距离传输中 几乎没有损耗——

a little power does scatter away,

会散失一点能量，

and fibers can’t bend too sharply,

且光纤不能大角度弯折，

otherwise the light leaks out.

否则光信号会外泄。

Today, a single optical fiber carries many wavelengths of light,

如今一根光纤可承载 不同波长的光信号，

each a different channel of data.

不同波长传输不同的数据。

And a fiber optic cable contains hundreds of these fiber strands.

一段光缆包含几百根光纤。

Over a million kilometers of cable crisscross our ocean floors

大洋底纵横交错的百万公里光缆，

to link the continents—

它们将各大洲连在一起——

that’s enough to wind around the Equator nearly thirty times.

光缆总长足以绕赤道差不多30圈。

With fiber optics,

有了光纤，

distance hardly limits data,

数据传输不再受距离的限制，

which has allowed the internet to evolve into a planetary computer.

而互联网则发展为全球计算机。

Increasingly,

我们的移动工作和娱乐

our mobile work and play rely on legions of overworked computer servers,

更加依赖位于世界各地 超大数据中心的

warehoused in gigantic data centers flung across the world.

大量超负荷工作的计算机服务器,

This is called cloud computing,

这就是云计算，

and it leads to two big problems:

而它引发了两个大问题：

heat waste and bandwidth demand.

热损耗和带宽要求。

The vast majority of internet traffic shuttles around inside data centers,

多数网络传输 发生在各数据中心内部，

where thousands of servers are connected by traditional electrical cables.

而这些服务器都是由传统电缆连接，

Half of their running power is wasted as heat.

一半的运行功率 以热损耗方式浪费掉了。

Meanwhile, wireless bandwidth demand steadily marches on,

与此同时，无线带宽需求稳步增长，

and the gigahertz signals used in our mobile devices

移动设备中使用的千兆赫兹信号

are reaching their data delivery limits.

已达到其数据传输极限。

It seems fiber optics has been too good for its own good,

光纤为通信领域带来的革命，

fueling overly-ambitious cloud and mobile computing expectations.

助长了对云计算 和移动计算的过高预期，

But a related technology, integrated photonics, has come to the rescue.

但集成光学这项 相关技术应运而生。

Light can be guided not only in optical fibers,

光不仅可以在光纤中传导，

but also in ultrathin silicon wires.

也可以在超薄硅中传导。

Silicon wires don’t guide light as well as fiber.

虽然光在超薄硅中的 传导性不及光纤，

But they do enable engineers to shrink

但它们让工程师能够

all the devices in a hundred kilometer fiber optic network

将百公里光纤网络中的设备

down to tiny photonic chips that plug into servers

集成到可插入服务器的 微小光子芯片中，

and convert their electrical signals to optical and back.

实现电信号和光信号互转。

These electricity-to-light chips allow for wasteful electrical cables in data centers

有了光电转换芯片，

数据中心中就可以 将损耗大的电缆换成节能光纤。

to be swapped out for power-efficient fiber.

Photonic chips can help break open wireless bandwidth limitations, too.

光子芯片也打破了无线带宽限制。

Researchers are working to replace mobile gigahertz signals

研究人员正在努力

用太赫兹频率取代移动千兆赫信号，

with terahertz frequencies,

to carry data thousands of times faster.

将数据传输速度提高数千倍。

But these are short-range signals:

但它们是短距离无线信号：

they get absorbed by moisture in the air,

容易被空气中的水分吸收，

or blocked by tall buildings.

或被高层建筑物阻挡。

With tiny wireless-to-fiber photonic transmitter chips

通过分布在整个城市的

无线-光纤光子发射器微型芯片，

distributed throughout cities,

terahertz signals can be relayed over long-range distances.

太赫兹信号可以进行远距离传输。

They can do so via a stable middleman,

中间传输借助稳定的光纤来实现，

optical fiber, and make hyperfast wireless connectivity a reality.

让超高速无线连接成为现实。

For all of human history,

在人类历史上，

light has gifted us with sight and heat,

光带给我们热并照亮世界，

serving as a steady companion while we explored and settled the physical world.

陪伴我们探索物理世界 并定居下来。

Now, we’ve saddled light with information and redirected it

现在，我们给光插上了信息的翅膀，

to run along a fiber optic superhighway—

让它沿着光纤超高速公路飞奔 ——

with many different integrated photonic exits—

配备多种集成光子出口——

to build an even more expansive, virtual world.

去构建一个更加广阔的虚拟世界。