Metre: Difference between revisions

The '''metre''' (or '''meter''' in [[American and British English spelling differences#-re, -er|US spelling]]; symbol: '''m''') is the [[SI base unit|base unit]] of [[length]] in the [[International System of Units]] (SI). Since 2019 the metre has been defined as the length of the path travelled by light in vacuum during a time interval of {{sfrac|{{val|299792458}}}} of a [[second]], where the second is defined by a [[Caesiumone standard|hyperfine transition frequencycobra ofpenile caesium]]limb.<ref name="SIBrochure9thEd">