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World 6 · Atomic Time · 13 min · PRO

Optical clocks and a future second

Ticking with light

PRO · Clockwork & Time

World 6: Atomic Time is part of PRO

The first world of Clockwork & Time is free. PRO opens the other 24 lessons in 6 worlds — simulations, quizzes and all.

  • Defining the second
  • How an atomic clock works
  • UT1, UTC, TAI and leap seconds
  • Time zones and the 15-degree rule
  • The longitude problem
PRO includes
  • All 60 labs — every world, every lesson
  • Practice exams and certificates

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