19 Mar 2020 – noon GMT – 7°C Mostly Cloudy – Co. Dublin, Ireland
We are exercising to stay fit. Outstretched arms, fingertip to fingertip, conveniently called a fathom in English. An anatomical unit of measure like cubit nor passus. Not really six feet either but once measures were standardised, it became six feet, then the unit of depth via weighted plumb-line measurements and now, I’ve got to the bottom of it. The largest of the anatomically inspired units. From a time when social isolations were the norm. Today we might call it 1.8288 metres but that requires a standard for the metre that we can’t carry with us. A metre today is the fixed numerical value of the speed of light in vacuum c to be 299 792 458 when expressed in the unit m⋅s−1, where the second is defined in terms of the caesium frequency ΔνCs. Imagine meeting a German who knew the ‘faden’ to be 1.7 metres or a Swede who used the ‘gamn’ for 1.784 metres or buying a length of silk from a Dutch trader selling in ‘vadem’ units equivalent to 1.818 metres. Reminds me of the international response to the Covid pandemic. Each nation cutting its cloth to its own measure despite globalised funding for a World Health Organisation. We know the metre was proposed by the French who defined it as one ten-millionth of the shortest distance from the North Pole to the equator passing through Paris. Not every country uses SI units and of those that do, some spell it differently. Thank you to China and South Korea for leading the way on Covid transmission mitigation and suppression. Sorry that global cooperation remains immature.
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