Science, Physics, Standards, Measurement, Quantum Physics.
K20 and Friends: Four of the five U.S. national prototype kilogram artifacts, including K20 (front) and K4 (back). Credit: J. Lee/NIST  Jon Pratt, Chief, Quantum Measurements Division It was Monday, April 25, 2016, and I was going to meet mass experts Pat Abbott and Eddie Mulhern of NIST’s Mass and