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In 2012,

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a team of Japanese and Danish researchers[br]set a world record,

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transmitting 1 petabit of data—

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

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over a fifty-kilometer cable, in a second.

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This wasn’t just any cable.

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It was a souped-up version [br]of fiber optics—

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the hidden network that links our planet

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and makes the internet possible.

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For decades,

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long-distance communications [br]between cities and countries

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were carried by electrical signals,

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in wires made of copper.

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This was slow and inefficient,

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

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But in the late 20th century,

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engineers mastered a far superior method[br]of transmission.

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Instead of metal,

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

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hundreds of kilometers long [br]and no thicker than human hair.

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And instead of electricity,

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these strands carry pulses of light, [br]representing digital data.

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

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

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Since Isaac Newton’s time,

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lensmakers and scientists have [br]known that light bends

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

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

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it refracts, or bends [br]as it exits into air.

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But if the ray travels at a shallow angle,

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it’ll bend so far that it stays trapped,

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bouncing along inside the glass.

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Under the right condition,

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

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Compared to electricity or radio,

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fiber optic signals barely degrade [br]over great distances—

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a little power does scatter away,

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and fibers can’t bend too sharply,

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otherwise the light leaks out.

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Today, a single optical fiber carries many[br]wavelengths of light,

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each a different channel of data.

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And a fiber optic cable contains hundreds [br]of these fiber strands.

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Over a million kilometers of cable [br]crisscross our ocean floors

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to link the continents—

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

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With fiber optics,

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distance hardly limits data,

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

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Increasingly,

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

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warehoused in gigantic data centers [br]flung across the world.

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This is called cloud computing,

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and it leads to two big problems:

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heat waste and bandwidth demand.

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

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where thousands of servers are connected [br]by traditional electrical cables.

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Half of their running power [br]is wasted as heat.

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Meanwhile, wireless bandwidth demand [br]steadily marches on,

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and the gigahertz signals used in our [br]mobile devices

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are reaching their data delivery limits.

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

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fueling overly-ambitious cloud and mobile[br]computing expectations.

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

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Light can be guided not [br]only in optical fibers,

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but also in ultrathin silicon wires.

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Silicon wires don’t guide light[br]as well as fiber.

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But they do enable engineers to shrink

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all the devices in a hundred kilometer [br]fiber optic network

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down to tiny photonic chips that plug[br]into servers

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and convert their electrical signals [br]to optical and back.

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

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to be swapped out for [br]power-efficient fiber.

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

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Researchers are working to replace mobile[br]gigahertz signals

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with terahertz frequencies,

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to carry data thousands of times faster.

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But these are short-range signals:

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they get absorbed by moisture in the air,

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or blocked by tall buildings.

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With tiny wireless-to-fiber photonic [br]transmitter chips

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distributed throughout cities,

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terahertz signals can be relayed over [br]long-range distances.

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They can do so via a stable middleman,

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optical fiber, and make hyperfast [br]wireless connectivity a reality.

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For all of human history,

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light has gifted us with sight and heat,

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

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

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to run along a fiber optic superhighway—

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with many different integrated [br]photonic exits—

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to build an even more expansive, [br]virtual world.