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  2. Atomic clock - Wikipedia

    en.wikipedia.org/wiki/Atomic_clock

    An atomic clock is based on a system of atoms which may be in one of two possible energy states. A group of atoms in one state is prepared, then subjected to microwave radiation. If the radiation is of the correct frequency, a number of atoms will transition to the other energy state.

  3. Doomsday Clock - Wikipedia

    en.wikipedia.org/wiki/Doomsday_Clock

    The Doomsday Clock is a symbol that represents the likelihood of a human-made global catastrophe, in the opinion of the members of the Bulletin of the Atomic Scientists. [1] Maintained since 1947, the Clock is a metaphor, not a prediction, for threats to humanity from unchecked scientific and technological advances. That is, the time on the ...

  4. History of timekeeping devices - Wikipedia

    en.wikipedia.org/wiki/History_of_timekeeping_devices

    The invention of the verge and foliot escapement in c.1275 [87] was one of the most important inventions in both the history of the clock [88] and the history of technology. [89] It was the first type of regulator in horology. [6] A verge, or vertical shaft, is forced to rotate by a weight-driven crown wheel, but is stopped from rotating freely ...

  5. Timeline of time measurement inventions - Wikipedia

    en.wikipedia.org/wiki/Timeline_of_time...

    1676 - Daniel Quare, a London clock-maker, invents the repeating clock, that chimes the number of hours (or even minutes). [ 7] 1680 - Second hand introduced. 1737 - John Harrison presents the first stable marine chronometer, thereby allowing for precise longitude determination while at sea. 1850 - Aaron Lufkin Dennison starts in Roxbury, Mass ...

  6. International Atomic Time - Wikipedia

    en.wikipedia.org/wiki/International_Atomic_Time

    International Atomic Time. International Atomic Time (abbreviated TAI, from its French name temps atomique international[1]) is a high-precision atomic coordinate time standard based on the notional passage of proper time on Earth's geoid. [2] TAI is a weighted average of the time kept by over 450 atomic clocks in over 80 national laboratories ...

  7. List of atomic clocks - Wikipedia

    en.wikipedia.org/wiki/List_of_atomic_clocks

    Department of Defense master clock. United States Naval Observatory. Washington, D.C. United States. 18 cesium atomic clocks and 4 hydrogen maser clocks. Cs, H. National Institute of Information and Communications Technology. Koganei, Japan [ 13 ] Optical lattice clock.

  8. Radio clock - Wikipedia

    en.wikipedia.org/wiki/Radio_clock

    Radio clock. A modern LF radio-controlled clock. A radio clock or radio-controlled clock (RCC), and often colloquially (and incorrectly [1]) referred to as an "atomic clock", is a type of quartz clock or watch that is automatically synchronized to a time code transmitted by a radio transmitter connected to a time standard such as an atomic clock.

  9. Nuclear clock - Wikipedia

    en.wikipedia.org/wiki/Nuclear_clock

    A nuclear clock or nuclear optical clock is a atomic clock being developed that will use the energy of a nuclear isomeric transition as its reference frequency, [1] instead of the atomic electron transition energy used by conventional atomic clocks. Such a clock is expected to be more accurate than the best current atomic clocks by a factor of ...