c: float = 299792458.0
"""The speed of light in vacuum."""

mu_0: float = 1.25663706212e-06
r"""The vacuum permeability :math:`\mu_0`."""

epsilon_0: float = 8.8541878128e-12
r"""The vacuum permittivity :math:`\epsilon_0`."""

z_0: float = 376.73031341259
r"""The impedance of free space :math:`Z_0`."""
