the.com/metre
The length light travels in 1/299,792,458 seconds — distance defined by speed, not the other way round.
means The base unit of length in the metric system, originally meant to be a fixed, rational measure derived from the Earth itself.
from From French mètre, from Greek metron, 'a measure' — the same root behind 'meter' and 'metric.' Coined during the French Revolution, when reformers tried to scrap the old patchwork of royal feet and local cubits and replace them with something universal: one ten-millionth of the distance from the North Pole to the Equator. Science kept redefining it as measurement got more precise — through a platinum bar, then the wavelength of krypton light — until 1983, when it was pinned to the speed of light itself, so the ancient Greek idea of 'measure' ended up anchored to the fastest thing in the universe.
- original plan
- one ten-millionth of equator-to-pole distance
- measurement error
- surveyors botched it, metre slightly short
- old standard
- a platinum bar in a Paris vault
- american spelling
- meter, same thing, different vowels