1 00:00:00,080 --> 00:00:02,800 Speaker 1: From a single computer to tens of thousands of computers 2 00:00:02,800 --> 00:00:06,080 Speaker 1: and servers. Mosey by e MC protects data and files 3 00:00:06,080 --> 00:00:09,280 Speaker 1: with the most trusted cloud backup service for business. Visit 4 00:00:09,360 --> 00:00:12,000 Speaker 1: Mosey dot com to learn more. That's m o z 5 00:00:12,320 --> 00:00:16,560 Speaker 1: Y dot com. Mosey, It's always there. Welcome to brain 6 00:00:16,600 --> 00:00:19,840 Speaker 1: Stuff from how Stuff Works dot com where smart Happens 7 00:00:27,720 --> 00:00:30,200 Speaker 1: h I am Marshall Brain with today's question, how does 8 00:00:30,240 --> 00:00:34,000 Speaker 1: a fiber optic cable work? Over the last thirty years 9 00:00:34,080 --> 00:00:37,839 Speaker 1: or so, fiber optic cables have taken over and transformed 10 00:00:37,840 --> 00:00:41,839 Speaker 1: the long distance telephone industry. Optical fibers are also a 11 00:00:41,960 --> 00:00:44,880 Speaker 1: huge part of making the Internet available around the world. 12 00:00:45,320 --> 00:00:49,519 Speaker 1: When fiber replaces copper for long distance calls and Internet traffic, 13 00:00:49,600 --> 00:00:53,800 Speaker 1: it dramatically lowers costs. To understand how a fiber optic 14 00:00:53,880 --> 00:00:58,760 Speaker 1: cable works, imagine an immensely long drinking straw or flexible 15 00:00:58,800 --> 00:01:03,400 Speaker 1: plastic pipe. For example, imagine a pipe that's several miles long. 16 00:01:03,920 --> 00:01:06,600 Speaker 1: Now imagine that the inside surface of the pipe has 17 00:01:06,640 --> 00:01:10,120 Speaker 1: been coated with a perfect mirror. Now imagine that you 18 00:01:10,160 --> 00:01:13,560 Speaker 1: are looking into one end of the pipe several miles away. 19 00:01:13,600 --> 00:01:16,320 Speaker 1: At the other end, a friend turns on a flashlight 20 00:01:16,360 --> 00:01:19,560 Speaker 1: and shines it into the pipe. Because the interior of 21 00:01:19,600 --> 00:01:22,920 Speaker 1: the pipe is a perfect mirror, the flashlights light will 22 00:01:22,959 --> 00:01:25,560 Speaker 1: reflect off the sides of the pipe, even though the 23 00:01:25,640 --> 00:01:28,280 Speaker 1: pipe may curve and twist, and you will see the 24 00:01:28,400 --> 00:01:30,920 Speaker 1: light at the other end. If your friend were to 25 00:01:30,959 --> 00:01:33,880 Speaker 1: turn the flashlight on and off in a Morse code fashion, 26 00:01:34,280 --> 00:01:37,559 Speaker 1: your friend could communicate with you through this pipe. That 27 00:01:37,760 --> 00:01:41,039 Speaker 1: is the essence of a fiber optic cable. Making a 28 00:01:41,120 --> 00:01:43,679 Speaker 1: cable out of a mirror tube would work, but it 29 00:01:43,680 --> 00:01:46,039 Speaker 1: would be bulky and it would be very hard to 30 00:01:46,120 --> 00:01:48,800 Speaker 1: coat the interior of the tube with a perfect mirror. 31 00:01:49,080 --> 00:01:52,160 Speaker 1: A real fiber optic cable is therefore made out of glass. 32 00:01:52,560 --> 00:01:56,360 Speaker 1: The glass is incredibly pure, so that even though it's 33 00:01:56,400 --> 00:02:00,600 Speaker 1: several miles long, light can still make it through. Imagine 34 00:02:00,600 --> 00:02:04,480 Speaker 1: glass so transparent that a window several miles sticks still 35 00:02:04,480 --> 00:02:08,120 Speaker 1: looks clear. The glass is drawn into a very thin 36 00:02:08,360 --> 00:02:11,640 Speaker 1: strand with a thickness comparable to that of a human hairror. 37 00:02:12,040 --> 00:02:15,400 Speaker 1: The glass strand is then coated in several layers of plastic. 38 00:02:16,120 --> 00:02:19,239 Speaker 1: By coating the glass in plastic, you get the equivalent 39 00:02:19,320 --> 00:02:23,400 Speaker 1: of a mirror around the glass. Strand this mirror creates 40 00:02:23,480 --> 00:02:27,040 Speaker 1: total internal reflection, just like a perfect mirror coating on 41 00:02:27,080 --> 00:02:30,160 Speaker 1: the inside of a tube does. You can experience this 42 00:02:30,240 --> 00:02:32,960 Speaker 1: sort of reflection with a flashlight and a window in 43 00:02:33,000 --> 00:02:36,200 Speaker 1: a dark room. If you direct the flashlight through the 44 00:02:36,240 --> 00:02:39,399 Speaker 1: window at a ninety degree angle, it passes straight through 45 00:02:39,400 --> 00:02:42,679 Speaker 1: the glass. However, if you shine the flashlight at a 46 00:02:42,800 --> 00:02:46,880 Speaker 1: very shallow angle nearly parallel to the glass, the glass 47 00:02:46,880 --> 00:02:49,440 Speaker 1: will act as a mirror and you will see the 48 00:02:49,480 --> 00:02:52,839 Speaker 1: beam reflect off the window and hit the wall opposite 49 00:02:52,919 --> 00:02:55,960 Speaker 1: on the inside of the room. Light traveling through the 50 00:02:56,000 --> 00:02:59,720 Speaker 1: fiber bounces at shallow angles like this and stays completely 51 00:02:59,720 --> 00:03:03,760 Speaker 1: within the fiber. To send telephone conversations through a fiber 52 00:03:03,760 --> 00:03:08,760 Speaker 1: optic cable, analog voice signals are translated into digital signals. 53 00:03:08,800 --> 00:03:11,440 Speaker 1: A laser at one end of the pipe switches on 54 00:03:11,600 --> 00:03:15,160 Speaker 1: and off to send each bit. Modern fiber systems with 55 00:03:15,240 --> 00:03:18,760 Speaker 1: a single laser can transmit billions of bits per second. 56 00:03:19,160 --> 00:03:22,040 Speaker 1: The laser can turn on and off several billion times 57 00:03:22,080 --> 00:03:26,240 Speaker 1: per second. The newest systems use lasers with multiple colors 58 00:03:26,280 --> 00:03:30,320 Speaker 1: to fit multiple signals into the same fiber. Modern fiber 59 00:03:30,360 --> 00:03:33,800 Speaker 1: optic cables can carry a signal quite a distance, perhaps 60 00:03:33,880 --> 00:03:37,840 Speaker 1: sixty miles or a hundred kilometers. On a long distance line, 61 00:03:38,200 --> 00:03:41,800 Speaker 1: there is an equipment hut every forty or fifty miles. 62 00:03:41,840 --> 00:03:45,520 Speaker 1: The hut contains equipment that picks up and retransmits the 63 00:03:45,560 --> 00:03:49,480 Speaker 1: signal down the next segment at full strength. Do you 64 00:03:49,520 --> 00:03:52,920 Speaker 1: have any ideas or suggestions for this podcast? If so, 65 00:03:53,080 --> 00:03:55,720 Speaker 1: please send me an email at podcast at how stuff 66 00:03:55,760 --> 00:03:58,520 Speaker 1: works dot com. For more on this and thousands of 67 00:03:58,520 --> 00:04:01,800 Speaker 1: other topics, go to how stuffs dot com and be 68 00:04:01,880 --> 00:04:04,000 Speaker 1: sure to check out the brain stuff blog on the 69 00:04:04,040 --> 00:04:10,560 Speaker 1: house stuff works dot com home page. Protect your organization's 70 00:04:10,560 --> 00:04:13,280 Speaker 1: critical files with Mosey by e m C, the most 71 00:04:13,320 --> 00:04:16,120 Speaker 1: trusted name in cloud backup. Don't leave the security of 72 00:04:16,120 --> 00:04:19,200 Speaker 1: your business critical files to anyone but Mosey by e MC. 73 00:04:19,520 --> 00:04:22,160 Speaker 1: Visit Mosey dot com or ask your I T provider 74 00:04:22,200 --> 00:04:25,720 Speaker 1: from Mosey Cloud Backup. That's m o z y dot com.