femto = 1e-15
atto = 1e-18
zepto = 1e-21
#binary prefixes
kibi = 2**10
mebi = 2**20
gibi = 2**30
tebi = 2**40
pebi = 2**50
exbi = 2**60
zebi = 2**70
yobi = 2**80
#physical constants
c = speed_of_light = _cd('speed of light in vacuum')
mu_0 = 4e-7*pi
epsilon_0 = 1 / (mu_0*c*c)
h = Planck = _cd('Planck constant')
hbar = h / (2 * pi)
G = gravitational_constant = _cd('Newtonian constant of gravitation')
g = _cd('standard acceleration of gravity')
e = elementary_charge = _cd('elementary charge')
R = gas_constant = _cd('molar gas constant')
alpha = fine_structure = _cd('fine-structure constant')
N_A = Avogadro = _cd('Avogadro constant')
k = Boltzmann = _cd('Boltzmann constant')
sigma = Stefan_Boltzmann = _cd('Stefan-Boltzmann constant')
Wien = _cd('Wien wavelength displacement law constant')
Rydberg = _cd('Rydberg constant')
femto = 1e-15
atto = 1e-18
zepto = 1e-21
#binary prefixes
kibi = 2**10
mebi = 2**20
gibi = 2**30
tebi = 2**40
pebi = 2**50
exbi = 2**60
zebi = 2**70
yobi = 2**80
#physical constants
c = speed_of_light = _cd('speed of light in vacuum')
mu_0 = 4e-7*pi
epsilon_0 = 1 / (mu_0*c*c)
h = Planck = _cd('Planck constant')
hbar = h / (2 * pi)
G = gravitational_constant = _cd('Newtonian constant of gravitation')
g = _cd('standard acceleration of gravity')
e = elementary_charge = _cd('elementary charge')
R = gas_constant = _cd('molar gas constant')
alpha = fine_structure = _cd('fine-structure constant')
N_A = Avogadro = _cd('Avogadro constant')
k = Bolzmann = _cd('Boltzmann constant')
sigma = Stefan_Bolzmann = _cd('Stefan-Boltzmann constant')
Wien = _cd('Wien wavelength displacement law constant')
Rydberg = _cd('Rydberg constant')