English subtitles

← How the compass unlocked the world

"Everything that we think of as world history would not have taken place without the compass." TED science curator David Biello explains how the device changed our relationship to the world.

Get Embed Code
23 Languages

Showing Revision 6 created 02/17/2020 by Brian Greene.

  1. Growing up in Missouri,
  2. they would kind of take us
    out into the woods,
  3. and they would give you a map,
    and they would give you a compass,
  4. and you had to find your way home.
  5. And without the compass,
  6. you can't even read the map.
  7. That's what I'm here to tell you.
  8. The compass is the key.
  9. [Small thing.]

  10. [Big idea.]

  11. A compass is most simply a piece of metal
    that has been magnetized,

  12. so that it will turn towards
    the Earth's magnetic pole.
  13. The one that we all think of
    is the pocket compass.
  14. It looks like a watch, right?
  15. You can hold it in your hand
  16. and watch the little needle bounce around
  17. until you find north.
  18. Magnetism is still a pretty
    mysterious force to physicists,

  19. but what we do know for sure
    is that a compass works
  20. because the Earth is this giant magnet.
  21. And when you use a compass,
  22. you are in touch with
    the very center of our planet,
  23. where this kind of roiling
    ball of molten iron
  24. is spinning around
    and creating a magnetic field.
  25. Just like a magnet you can
    play with on your tabletop,
  26. it has a north pole and a south pole,
  27. and we use compasses to find our way
    north because of that fact.
  28. The earliest known compass comes
    from about 200 BC in China.

  29. They figured out that some of the metal
    coming out of the ground
  30. was naturally magnetic,
  31. and so they fashioned
    this magnetized metal
  32. into this kind of ladle-looking thing,
  33. put it on a brass plate
  34. and then it would point north.
  35. It seems to have been primarily
    used to improve feng shui,
  36. so they could figure out
    what was the best way for energy to flow
  37. through their living spaces.
  38. Sailors were probably the early adopters

  39. of the more portable versions of it,
  40. because no matter where the sun was,
  41. no matter what the condition
    of the stars were,
  42. they would always
    be able to find north.
  43. Now, much later, the Europeans
    are the ones who innovate

  44. and come up with the compass rose.
  45. It essentially laid out
  46. what north, south, east
    and west looked like,
  47. and it also enabled you
    to kind of create new directions,
  48. like northwest, southeast, what have you.
  49. And for the first time,
    they knew where they were going.
  50. That's kind of a big deal.
  51. But also, I think it was part
    of this general reinvigoration

  52. of European science.
  53. You might know it as the Renaissance.
  54. Lots of new tools were invented,
  55. from the telescope to the microscope.
  56. Maps got better because
    of compasses, right?

  57. Because then you start to understand
    which direction is which,
  58. you get a lot more detail,
  59. and that just kind of changes
  60. the human relationship to the world.
  61. The compass with a map
    is like a superpower.
  62. Everything that we think
    of as world history
  63. would not have taken place
    without the compass:
  64. the age of exploration, Magellan
    circumnavigating the globe,
  65. even the fact that we know it is a globe.
  66. The compass ends up getting embedded
    in all these other tools,

  67. because it is such a functional object.
  68. So you might have it
    embedded in your multi-tool,
  69. you might have it
    embedded in your phone.
  70. The compass is everywhere,
  71. because it's literally how we find our way
    across the face of the Earth.
  72. So you can go off and explore,
  73. and find out what is over that next hill
    or that next horizon,
  74. but you can also reliably
    find your way home.