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Duration:05:36
Uploaded:2021-03-11
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Thanks to Qualcomm for sponsoring a portion of this video. Learn more at https://www.qualcomm.com/products/mobile-computing/mobile-pcs



The tools and resources the internet provides us have undoubtedly become everyday necessities for a large portion of the world. That technology would not have been possible without the research of an often overlooked scientist named Narinder Singh Kapany, who learned how to bend light.

Hosted by: Hank Green

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A portion of this video was sponsored by Qualcomm.

To learn more about the Qualcomm Snapdragon 8cx 5G compute platform, click the link in the description.  [♪ INTRO]. With streaming services and worldwide video chats being so normal these days, it’s easy to take the internet for granted.

But an absurd amount of technology goes into making it work. And a big piece of the puzzle is fiber optics, which much of the internet uses to send data over vast distances.  But while the technology is now world-famous, one of the most important minds behind it is often overlooked: an Indian inventor named Narinder Singh Kapany, who learned how to bend light. Bending light is key to fiber optics, which uses thin glass fibers to send light encoded with data all over the planet.  And it works thanks to a phenomenon called total internal reflection.

In fiber optics, a beam of light shoots into a glass tube at a specific, shallow angle. And when that light hits the edge of the glass, it reflects perfectly back into the tube. Then, the beam can travel all the way down a fiber this way, bouncing back and forth until it comes out the other end.

Now, total internal reflection isn’t new, or limited to glass tubes. In fact, people have known about it since ancient times. But it was the 20th century before anyone thought about using it to transmit light down tubes.

That’s where Narinder Singh Kapany entered the picture. Kapany was born in India in 1926. And ever since he was in high school, he'd wondered if it was possible to bend light.

He’d always been taught that light only travels in straight lines, which is generally true. But he wanted to figure out a way to make light curve. The problem followed him through college, and after he graduated from Agra University in India in 1948, he went to Imperial College London for a PhD in optics.

That was where he finally got the chance to take the problem of bending light into his own hands.  At the time, though, he and his PhD advisor, Harold Hopkins, weren’t even thinking about communications tech. They were interested in how bending light could improve medical imaging.  Because back then, the endoscopes doctors used to look inside people didn’t produce great images, and the instruments were rigid, which was not ideal for, like, moving around inside a body. But Kapany and Hopkins had an idea for a new tool that would be flexible and produce much sharper images.

They called it a fiberscope.  It was a bundle of thousands of glass fibers 75 centimeters long, and each fiber was sort of like one pixel.  Light bouncing off an object would enter one end of a fiber, and then come out the other end. Then, you could then combine all those pinpricks of light to form an image. Those images were clear and sharp.

And the fibers were bendy, so light could travel through the body in curved paths, which was a huge success! In fact, the fiberscope worked so well that today, modern endoscopes are still based on that same general technology. But it wasn’t just the invention that was groundbreaking.

It was the general principle they showed: that glass fibers could reliably transmit light. Now, at this point, the technology was still only reliable across short distances. Over longer distances, light would get absorbed by molecules and scatter in random directions so that the sharp beam eventually fizzled out.

But in the ‘60s, the physicist Charles Kao finally figured out the key to making fiber-optic cables reliable over long distances. He realized that the losses were mainly from impurities in the glass, not the glass itself. So, by making purer glass, he could reduce losses.

Kao also understood that you could get even better results by adding impurities called dopants. These change the speed of light in the glass, which affects how much the beam spreads out. And that kicked off the race to make the purest glass fibers and the best dopants.

And in 1970, an American team made a big breakthrough when they developed silica fibers doped with titanium to drastically reduce losses.  Finally, light could travel down long fibers and a sharp signal would come out the other end. These advances in fiber optics eventually opened the door to the modern internet, since long, flexible fiber-optic cables are great for sending light packed with data over long distances. And today, cables like this run around the world—some of them thousands of kilometers long.

In 2009, Kao was awarded half of the Nobel Prize in Physics for his contribution to the internet. But Kapany was never recognized as widely. And yet, his early work was what made all of this possible.  By figuring out how to send light ricocheting down glass tubes, Kapany showed us how to bend light, which laid the foundations for the Information Age.

This portion of the video was sponsored by Qualcomm. Their Snapdragon 8cx 5G compute platform powered the world’s first 5G PC. And with a built-in 5G modem, multi-day battery life, advanced AI capabilities, and more, it combines the power and performance of a traditional laptop with some of the best of smartphone features.

Devices using Snapdragon 8cx 5G are light and fanless, staying quiet and cool, and thanks to the built-in 5G and 4G connectivity, there’s no need to connect to unsecure Wi-Fi or to tether to a mobile hotspot. Whether you need a computer for class or are trying to find a laptop that will work on the go, you can click the link in the description to learn more about the specs of this platform. [♪ OUTRO].