### 40.1 Fundamental Constants

GSL_CONST_MKSA_SPEED_OF_LIGHT
The speed of light in vacuum, c.
GSL_CONST_MKSA_VACUUM_PERMEABILITY
The permeability of free space, \mu_0. This constant is defined in the MKSA system only.
GSL_CONST_MKSA_VACUUM_PERMITTIVITY
The permittivity of free space, \epsilon_0. This constant is defined in the MKSA system only.
GSL_CONST_MKSA_PLANCKS_CONSTANT_H
Planck's constant, h.
GSL_CONST_MKSA_PLANCKS_CONSTANT_HBAR
Planck's constant divided by 2\pi, \hbar.
GSL_CONST_NUM_AVOGADRO
GSL_CONST_MKSA_FARADAY
The molar charge of 1 Faraday.
GSL_CONST_MKSA_BOLTZMANN
The Boltzmann constant, k.
GSL_CONST_MKSA_MOLAR_GAS
The molar gas constant, R_0.
GSL_CONST_MKSA_STANDARD_GAS_VOLUME
The standard gas volume, V_0.
GSL_CONST_MKSA_STEFAN_BOLTZMANN_CONSTANT
GSL_CONST_MKSA_GAUSS