unyt.physical_constants module

Predefined useful physical constants

Note that all of these names can be imported from the top-level unyt namespace. For example:

>>> from unyt.physical_constants import gravitational_constant, solar_mass
>>> from unyt import AU
>>> from math import pi
>>> period = 2 * pi * ((1 * AU)**3 / (gravitational_constant * solar_mass))**0.5
>>> period.in_units('day')
unyt_quantity(365.26236846, 'day')
Constant Name Value Alternate Names
me 9.1094e-31 kg mass_electron, electron_mass
amu 1.6605e-27 kg atomic_mass_unit
Na 1.000000020023999 dimensionless Avogadros_number, avogadros_number
mp 1.6726e-27 kg proton_mass, mass_proton
mh 1.6737e-27 kg hydrogen_mass, mass_hydrogen
c 2.9979e+08 m/s clight, speed_of_light
σ_T 6.6525e-29 m**2 sigma_thompson, thompson_cross_section, cross_section_thompson, sigma_thomson, thomson_cross_section, cross_section_thomson
qp 1.6022e-19 C proton_charge, elementary_charge, charge_proton
qe -1.6022e-19 C electron_charge, charge_electron
kb 1.3806e-23 kg*m**2/(K*s**2) kboltz, boltzmann_constant
G 6.6741e-11 m**3/(kg*s**2) newtons_constant, gravitational_constant
h 6.6261e-34 kg*m**2/s planck_constant
hbar 1.0546e-34 kg*m**2/s reduced_planck_constant
σ 5.6704e-08 kg/(K**4*s**3) stefan_boltzmann_constant
Tcmb 2.726 K CMB_temperature
Msun 1.9884e+30 kg msun, m_sun, m_Sun, M_sun, M_Sun, solar_mass, mass_sun
Mjup 1.8985e+27 kg mjup, jupiter_mass, mass_jupiter
mercury_mass 3.3010e+23 kg mass_mercury
venus_mass 4.8673e+24 kg mass_venus
Mearth 6.0456e+24 kg mearth, earth_mass, mass_earth
mars_mass 6.4169e+23 kg mass_mars
saturn_mass 5.6846e+26 kg mass_saturn
uranus_mass 8.6819e+25 kg mass_uranus
neptune_mass 1.0243e+26 kg mass_neptune
m_pl 2.1765e-08 kg planck_mass
l_pl 1.6162e-35 m planck_length
t_pl 5.3912e-44 s planck_time
E_pl 1.9561e+09 J planck_energy
q_pl 1.8755e-18 C planck_charge
T_pl 1.4168e+32 K planck_temperature
mu_0 1.2566e-06 kg*m/(A**2*s**2) vacuum_permeability, magnetic_constant, μ_0
eps_0 8.8542e-12 A**2*s**4/(kg*m**3) vacuum_permittivity, electric_constant, ε_0, epsilon_0
R_inf 1.0974e+07 1/m rydberg_constant, R_∞
standard_gravity 9.80665 m/s**2