For anyone with even a passing interest in frequency standards, I recommend watching this recent seminar by Bill Phillips on recent changes to the SI. Bill prov

For anyone with even a passing interest in frequency standards, I recommend watching this recent seminar by Bill Phillips on recent changes to the SI. Bill provides some interesting history on atomic clocks, context on why Cs was chosen, and perspective on the remaining problems with the definition of the second. https://www.youtube.com/watch?v=9okt-3xLbH8 https://www.youtube.com/watch?v=9okt-3xLbH8