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Callie Higgins is a materials research engineer at the National Institute of Standards and Technology (NIST). She studies a special branch of additive manufacturing called vat photopolymerization
This is part 5 in a series. Read part 1, part 2, part 3 and part 4. The Leap Second Solution When atomic clocks were developed in the 1950s, scientists needed to match the time and frequency of these
It is February 1994 and I am on the research vessel R/V Moana Wave off the coast of Lanai, Hawaii, with the team of the Marine Optical BuoY (MOBY) project. The water is incredibly blue, and I can’t
This is part 4 in a series. Read part 1, part 2 and part 3. Greenwich Mean Time In the previous essay I introduced mean solar time, which averaged the annual variation in apparent solar time so as to
This is part 3 in a series. Read part 1 and part 2. Oscillators and Clocks In the previous essay, I introduced the ideas that frequency and time interval are closely related concepts, and that the