I remember how amazing it was when HP brought out their commercial atomic clock. Before that all atomic clocks had been custom made and were expensive and delicate. Back in 1968 and 69 I worked at a satellite communications station in Hawaii. When our custom made clock had to be reset they took it to the University of Hawaii and set it to their maser. Keeping time back then was a chore. Heck I remember when the best we had at work, back in the late 50s and early 60s, was a really good crystal oscillator in a full sized single bay rack. Every morning one of the technicians had to synchronize it with the time broadcast from WWV, the national time standard. It had a display that showed the phase of the local frequency with respect to the phase of the WWV broadcast. The technician carefully looked at that and made small adjustments to the frequency of our standard to match. And that was what we used to calibrate all of our time sensitive equipment, primarily frequency counters.
And I agree that too many people who make strange claims about relativity being all wrong would be left in the lurch if it was wrong, because so many things wouldn't work. And of course the HP test was just one of a huge number that have proved relativity is right at finer and finer levels ever since.
Bill Gill
