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Science Technology

Device That Revolutionized Timekeeping Receives an IEEE Milestone (ieee.org) 46

An anonymous reader writes: The invention of the atomic clock fundamentally altered the way that time is measured and kept. The clock helped redefine the duration of a single second, and its groundbreaking accuracy contributed to technologies we rely on today, including cellphones and GPS receivers. Building on the accomplishments of previous researchers, Harold Lyons and his colleagues at the U.S. National Bureau of Standards (now the National Institute of Standards and Technology), in Washington, D.C., began working in 1947 on developing an atomic clock and demonstrated it to the public two years later. Its design was based on atomic physics. The clock kept time by tracking the microwave signals that electrons in atoms emit when they change energy levels. This month the atomic clock received an IEEE Milestone. Administered by the IEEE History Center and supported by donors, the milestone program recognizes outstanding technical developments around the world.
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Device That Revolutionized Timekeeping Receives an IEEE Milestone

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  • Did they just use whatever the "reference time" was for some existing highly accurate clock? Or did they do a bunch of astronomical measurements and then set the atomic clock based on some astronomical reference that defined some specific time?

  • Not just accuracy but redefinition. Originally the second was based on astronomical measurements which would vary [nist.gov]. With this redefinition it's also easier for scientists to create their own accurate clock. The kilogram is still waiting for its redefinition.
  • Many years ago, I wound up doing a small contract/visit at the Naval Research Labs at the Navy Yards in DC. Partly by tradition, partly by necessity, the Navy has a healthy obsession with accurate time keeping, and I was working with the Navy's time geeks. They were a fascinating group of guys to work with, their equipment and clocking was accurate enough to measure the (electrical) distance to a satellite in geosynchronous orbit to within half an inch.

    Anyhow, I was having lunch in his office and there on t

  • They [ethw.org] made a plaque which reads:

    The first atomic clock, developed near this site by Harold Lyons at the National Bureau of Standards, revolutionized timekeeping by using transitions of the ammonia molecule as its source of frequency. Far more accurate than previous clocks, atomic clocks quickly replaced the Earth’s rotational rate as the reference for world time. Atomic clock accuracy made possible many new technologies, including the Global Positioning System (GPS).

    and posted it in a park in Washington DC near where the original work was done.

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