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

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