full transcript

From the Ted Talk by Daniel Finkel: Can you solve the vampire hunter riddle?

Unscramble the Blue Letters

Let’s draw the chembar on a coordinate grid, with the Southwest corner at the point (0,0). The light passes through grid points with coordinates that are either both even or both odd. This is true even after it bounces off one or more walls. Another way of thinking about it is this: since the light travels at a 45 degree angle, it always crosses the diagonal of a unit square. teivarnlg 1 meter horizontally changes the x coordinate from even to odd or vice vsera. Traveling 1 meter vtlilacrey changes the y ctoroinade from even to odd or vice versa. Traveling diagonally – as the light does here – does both at once, so the x and y coordinates of any points the light passes through must be both even, or both odd. This oaobetvrsin is more pofuewrl than it seems. In particular, it means that we have a way to identify the kinds of points the light won’t ever go through If one of the coordinates is even and the other is odd, the lgiht will miss them. That means it’ll miss the top two corners of the room, since those points have one even and one odd coordinate. The Southeast corner is the only oitpon for the diffuser.

Open Cloze

Let’s draw the _______ on a coordinate grid, with the Southwest corner at the point (0,0). The light passes through grid points with coordinates that are either both even or both odd. This is true even after it bounces off one or more walls. Another way of thinking about it is this: since the light travels at a 45 degree angle, it always crosses the diagonal of a unit square. _________ 1 meter horizontally changes the x coordinate from even to odd or vice _____. Traveling 1 meter __________ changes the y __________ from even to odd or vice versa. Traveling diagonally – as the light does here – does both at once, so the x and y coordinates of any points the light passes through must be both even, or both odd. This ___________ is more ________ than it seems. In particular, it means that we have a way to identify the kinds of points the light won’t ever go through If one of the coordinates is even and the other is odd, the _____ will miss them. That means it’ll miss the top two corners of the room, since those points have one even and one odd coordinate. The Southeast corner is the only ______ for the diffuser.

Solution

  1. light
  2. powerful
  3. observation
  4. traveling
  5. versa
  6. chamber
  7. coordinate
  8. option
  9. vertically

Original Text

Let’s draw the chamber on a coordinate grid, with the Southwest corner at the point (0,0). The light passes through grid points with coordinates that are either both even or both odd. This is true even after it bounces off one or more walls. Another way of thinking about it is this: since the light travels at a 45 degree angle, it always crosses the diagonal of a unit square. Traveling 1 meter horizontally changes the x coordinate from even to odd or vice versa. Traveling 1 meter vertically changes the y coordinate from even to odd or vice versa. Traveling diagonally – as the light does here – does both at once, so the x and y coordinates of any points the light passes through must be both even, or both odd. This observation is more powerful than it seems. In particular, it means that we have a way to identify the kinds of points the light won’t ever go through If one of the coordinates is even and the other is odd, the light will miss them. That means it’ll miss the top two corners of the room, since those points have one even and one odd coordinate. The Southeast corner is the only option for the diffuser.

Frequently Occurring Word Combinations

ngrams of length 2

collocation frequency
great chamber 2
southwest corner 2
light passes 2
vice versa 2
versa traveling 2

ngrams of length 3

collocation frequency
vice versa traveling 2

Important Words

  1. angle
  2. bounces
  3. chamber
  4. coordinate
  5. coordinates
  6. corner
  7. corners
  8. crosses
  9. degree
  10. diagonal
  11. diagonally
  12. diffuser
  13. draw
  14. grid
  15. horizontally
  16. identify
  17. kinds
  18. light
  19. means
  20. meter
  21. observation
  22. odd
  23. option
  24. passes
  25. point
  26. points
  27. powerful
  28. room
  29. southeast
  30. southwest
  31. square
  32. thinking
  33. top
  34. traveling
  35. travels
  36. true
  37. unit
  38. versa
  39. vertically
  40. vice
  41. walls