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Device That Revolutionized Timekeeping Receives an IEEE Milestone (ieee.org)
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.
"Atomic clocks are based on the periodic decay of radioactive isotopes."
No, they aren't. Radioactive decay is random and would make a terrible clock. The second is defined in terms of a electron transitions of the cesium-133 atom, which is the only stable isotope. Hydrogen maser clocks are even more stable timekeepers, but again, not based on a radioactive isotope.
"National Security is the chief cause of national insecurity." - Celine's First Law
Well, I was going to mod you up +1 Informative, but then I notice the goatse link... Now, since I'm writing this, I can't mod you down either. But at least I can warn others to check the links before clicking. (Note: The rest of the links appear to be legit.)
XML is like violence. If it doesn't solve your problem, you're not using enough of it. --AC