which unit is used to measure it?
Since 1983, the metre has been defined in the International System of Units (SI) as the distance light travels in vacuum in of a second.
Speed of light
Since 1983, the metre has been defined in the International System of Units (SI) as the distance light travels in vacuum in of a second. This definition fixes the speed of light in vacuum at exactly .
As a dimensional physical constant, the numerical value of is different for different unit systems.
In branches of physics in which appears often, such as in relativity, it is common to use systems of natural units of measurement or the geometrized unit system where . Using these units, does not appear explicitly because multiplication or division by1 does not affect the result.
who discovered that light travels faster than sound Abū Rayhān al-Bīrūnī define the 'speed of light' UNANSWERABLE the person who made the discovery, what is his profession? UNANSWERABLE what role does the speed of light play in physics? Invariance of the speed of light: In 1905 Einstein postulated that the speed at which light waves propagate in vacuum is independent both of the motion of the wave source and of the inertial frame of reference of the observer. what is its numerical value? UNANSWERABLE
wiki:19580996
Speed of light [SEP] Numerical value, notation, and units
Sometimes is used for the speed of waves in "any" material medium, and for the speed of light in vacuum. This subscripted notation, which is endorsed in official SI literature, has the same form as other related constants: namely, "μ" for the vacuum permeability or magnetic constant, "ε" for the vacuum permittivity or electric constant, and "Z" for the impedance of free space. This article uses exclusively for the speed of light in vacuum. Since 1983, the metre has been defined in the International System of Units (SI) as the distance light travels in vacuum in of a second. This definition fixes the speed of light in vacuum at exactly .