full transcript

From the Ted Talk by John Kitching: Who decides how long a second is?

Unscramble the Blue Letters


But before timekeeping could go fluly atomic, coneruits had to decide which atom would work best. This was the discussion in 1967, at the Thirteenth General cnrnoeefce of the International Committee for Weights and Measures. There are 118 elements on the peiiordc table, each with their own unique properties. For this task, the researchers were looking for several things. The element ndeeed to have long-lived and high frequency electron oscillation for precise, long-term timekeeping. To easily track this oscillation, it also needed to have a reliably measurable quantum spin— meaning the orientation of the axis about which the electron rotates— as well as a simple energy level structure— meaning the atcvie electrons are few and their state is slmpie to identify. Finally, it needed to be easy to vaiproze.

Open Cloze


But before timekeeping could go _____ atomic, _________ had to decide which atom would work best. This was the discussion in 1967, at the Thirteenth General __________ of the International Committee for Weights and Measures. There are 118 elements on the ________ table, each with their own unique properties. For this task, the researchers were looking for several things. The element ______ to have long-lived and high frequency electron oscillation for precise, long-term timekeeping. To easily track this oscillation, it also needed to have a reliably measurable quantum spin— meaning the orientation of the axis about which the electron rotates— as well as a simple energy level structure— meaning the ______ electrons are few and their state is ______ to identify. Finally, it needed to be easy to ________.

Solution


  1. countries
  2. conference
  3. periodic
  4. vaporize
  5. fully
  6. needed
  7. simple
  8. active

Original Text


But before timekeeping could go fully atomic, countries had to decide which atom would work best. This was the discussion in 1967, at the Thirteenth General Conference of the International Committee for Weights and Measures. There are 118 elements on the periodic table, each with their own unique properties. For this task, the researchers were looking for several things. The element needed to have long-lived and high frequency electron oscillation for precise, long-term timekeeping. To easily track this oscillation, it also needed to have a reliably measurable quantum spin— meaning the orientation of the axis about which the electron rotates— as well as a simple energy level structure— meaning the active electrons are few and their state is simple to identify. Finally, it needed to be easy to vaporize.

Frequently Occurring Word Combinations


ngrams of length 2

collocation frequency
gregorian calendar 2
atomic clocks 2


Important Words


  1. active
  2. atom
  3. atomic
  4. axis
  5. committee
  6. conference
  7. countries
  8. decide
  9. discussion
  10. easily
  11. easy
  12. electron
  13. electrons
  14. element
  15. elements
  16. energy
  17. finally
  18. frequency
  19. fully
  20. general
  21. high
  22. identify
  23. international
  24. level
  25. meaning
  26. measurable
  27. measures
  28. needed
  29. orientation
  30. oscillation
  31. periodic
  32. precise
  33. properties
  34. quantum
  35. reliably
  36. researchers
  37. simple
  38. state
  39. table
  40. task
  41. thirteenth
  42. timekeeping
  43. track
  44. unique
  45. vaporize
  46. weights
  47. work