Speed of light.

value = clight

clight returns the value of the vacuum speed of light in SI units (meters/second) in value.

The value is taken from the 2018 CODATA collection of recommended values.

amu, angstrom, avogadro, barn, bmagn, bohrrad, boltzm, echarge, emass, eps0, evolt, faraday, gammae, gfree, hartree, hbar, molgas, mu0, nmagn, nmass, planck, pmass, rydberg