Taking the measure…
It’s National Metric Week!
As we cheat on conversion, we might recall that it was on this date in 1960 that the meter (AKA “the metre”) was redefined for the fourth time to be 1,650,763.73 wavelengths in vacuum of the orange-red light radiation of the krypton-86 atom (transition between levels 2p10 and 5d5)– a specification 100 times more accurate than the previous (third) legal definition adopted in 1889.
