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← The hidden network that makes the internet possible - Sajan Saini

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Zeige Revision 5 erzeugt am 04/22/2019 von lauren mcalpine .

  1. In 2012,
  2. a team of Japanese and Danish researchers
    set a world record,
  3. transmitting 1 petabit of data—
  4. that’s 10,000 hours of high-def video—
  5. over a fifty-kilometer cable, in a second.
  6. This wasn’t just any cable.
  7. It was a souped-up version
    of fiber optics—
  8. the hidden network that links our planet
  9. and makes the internet possible.
  10. For decades,

  11. long-distance communications
    between cities and countries
  12. were carried by electrical signals,
  13. in wires made of copper.
  14. This was slow and inefficient,
  15. with metal wires limiting data rates
    and power lost as wasted heat.
  16. But in the late 20th century,
  17. engineers mastered a far superior method
    of transmission.
  18. Instead of metal,
  19. glass can be carefully melted and
    drawn into flexible fiber strands,
  20. hundreds of kilometers long
    and no thicker than human hair.
  21. And instead of electricity,
  22. these strands carry pulses of light,
    representing digital data.
  23. But how does light travel within glass,
    rather than just pass through it?

  24. The trick lies in a phenomenon known
    as total internal reflection.
  25. Since Isaac Newton’s time,
  26. lensmakers and scientists have
    known that light bends
  27. when it passes between air and
    materials like water or glass.
  28. When a ray of light inside glass hits its
    surface at a steep angle,
  29. it refracts, or bends
    as it exits into air.
  30. But if the ray travels at a shallow angle,
  31. it’ll bend so far that it stays trapped,
  32. bouncing along inside the glass.
  33. Under the right condition,
  34. something normally transparent to light
    can instead hide it from the world.
  35. Compared to electricity or radio,

  36. fiber optic signals barely degrade
    over great distances—
  37. a little power does scatter away,
  38. and fibers can’t bend too sharply,
  39. otherwise the light leaks out.
  40. Today, a single optical fiber carries many
    wavelengths of light,
  41. each a different channel of data.
  42. And a fiber optic cable contains hundreds
    of these fiber strands.
  43. Over a million kilometers of cable
    crisscross our ocean floors
  44. to link the continents—
  45. that’s enough to wind around the
    Equator nearly thirty times.
  46. With fiber optics,

  47. distance hardly limits data,
  48. which has allowed the internet to evolve
    into a planetary computer.
  49. Increasingly,
  50. our mobile work and play rely on legions
    of overworked computer servers,
  51. warehoused in gigantic data centers
    flung across the world.
  52. This is called cloud computing,
  53. and it leads to two big problems:
  54. heat waste and bandwidth demand.
  55. The vast majority of internet traffic
    shuttles around inside data centers,
  56. where thousands of servers are connected
    by traditional electrical cables.
  57. Half of their running power
    is wasted as heat.
  58. Meanwhile, wireless bandwidth demand
    steadily marches on,
  59. and the gigahertz signals used in our
    mobile devices
  60. are reaching their data delivery limits.
  61. It seems fiber optics has been too good
    for its own good,

  62. fueling overly-ambitious cloud and mobile
    computing expectations.
  63. But a related technology, integrated
    photonics, has come to the rescue.
  64. Light can be guided not
    only in optical fibers,

  65. but also in ultrathin silicon wires.
  66. Silicon wires don’t guide light
    as well as fiber.
  67. But they do enable engineers to shrink
  68. all the devices in a hundred kilometer
    fiber optic network
  69. down to tiny photonic chips that plug
    into servers
  70. and convert their electrical signals
    to optical and back.
  71. These electricity-to-light chips allow for
    wasteful electrical cables in data centers
  72. to be swapped out for
    power-efficient fiber.
  73. Photonic chips can help break open
    wireless bandwidth limitations, too.

  74. Researchers are working to replace mobile
    gigahertz signals
  75. with terahertz frequencies,
  76. to carry data thousands of times faster.
  77. But these are short-range signals:
  78. they get absorbed by moisture in the air,
  79. or blocked by tall buildings.
  80. With tiny wireless-to-fiber photonic
    transmitter chips
  81. distributed throughout cities,
  82. terahertz signals can be relayed over
    long-range distances.
  83. They can do so via a stable middleman,
  84. optical fiber, and make hyperfast
    wireless connectivity a reality.
  85. For all of human history,

  86. light has gifted us with sight and heat,
  87. serving as a steady companion while we
    explored and settled the physical world.
  88. Now, we’ve saddled light with information
    and redirected it
  89. to run along a fiber optic superhighway—
  90. with many different integrated
    photonic exits—
  91. to build an even more expansive,
    virtual world.