the.com/metrology
the obsessive science of measuring everything, including how wrong your ruler probably is
kilogram redefinedIn 2019 the kilo ditched its metal lump for physics constants
old standardA platinum cylinder once defined mass for 130 years
not meteorologyStudies measurement, not weather, despite endless confusion
defines the meterDistance light travels in 1/299,792,458 of a second
trillionth precisionAtomic clocks measure time to staggering decimal places