// This header file contains type-safe constants based on SI units (source: mostly 2022 CODATA). // The constants are sorted by category: defined constants, universal, electromagnetic, atomic and nuclear, physico-chemical, physical, mathematical, astronomical, and various. // USAGE: #include #pragma once #include namespace SI { namespace constant { #define CONSTANT(_name, _value, _base_unit) const auto _name = _base_unit(_value) // +++ DEFINED CONSTANTS +++ CONSTANT(caesium_frequency, 9'192'631'770, hertz); // the unperturbed ground state hyperfine transition frequency of the ceesium-133 atom CONSTANT(delta_v_Cs, 9'192'631'770, hertz); // (the symbol) CONSTANT(speed_of_light, 299'792'458, meters_per_second); // the speed of light in vacuum CONSTANT(c, 299'792'458, meters_per_second); // (the symbol) CONSTANT(Planck, 6.626'070'15e-34, jouleseconds); // the Planck constant CONSTANT(h, 6.626'070'15e-34, jouleseconds); // (the symbol) CONSTANT(elementary_charge, 1.602'176'634e-19, coulombs); // the elementary charge CONSTANT(e, 1.602'176'634e-19, coulombs); // (the symbol) CONSTANT(Boltzmann, 1.380'649e-23, joules_per_kelvin); // the Boltzmann constant CONSTANT(k, 1.380'649e-23, joules_per_kelvin); // (the symbol) CONSTANT(N_A, 6.02214076e23, per_mol); // the Avogadro constant CONSTANT(K_cd, 683, lumens_per_watt); // the luminous efficacy of monochromatic radiation of frequency 540 THz CONSTANT(g_n, 9.806'65, meters_per_second2); // standard acceleration of gravity (2022 CODATA) CONSTANT(atm, 101'325, pascals); // standard atmosphere (2022 CODATA) CONSTANT(ssp, 100'000, pascals); // standard-state pressure (2022 CODATA) // +++ UNIVERSAL CONSTANTS +++ CONSTANT(G, 6.67430e-11, meters3_per_kilogram_per_second2); // Newtonian constant of gravitation (2022 CODATA) CONSTANT(Z_0, 376.730'313'412, ohms); // characteristic impedance of vacuum (2022 CODATA) CONSTANT(epsilon_0, 8.854'187'8188e-12, farads_per_meter); // vacuum electric permittivity, symbol: ε_0, 2022 CODATA) CONSTANT(l_P, 1.616255e-35, meters); // Planck length (2022 CODATA) CONSTANT(m_P, 2.176434e-8, kilograms); // Planck mass (2022 CODATA) CONSTANT(T_P, 1.416784e32, kelvins); // Planck temperature (2022 CODATA) CONSTANT(t_P, 5.391247e-44, seconds); // Planck time (2022 CODATA) CONSTANT(h_bar, 1.054'571'817e-34, jouleseconds); // reduced Planck constant (2022 CODATA) CONSTANT(mu_0, 1.256'637'061'27e-6, newtons_per_ampere2); // vacuum magnetic permeability (2022 CODATA) // +++ ELECTROMAGNETIC CONSTANTS +++ CONSTANT(G_0, 7.748'091'729e-5, siemens); // conductance quantum (2022 CODATA) CONSTANT(G_0_inv, 12906.40372, ohms); // inverse conductance quantum CONSTANT(K_J, 483'597.848'4e9, hertz_per_volt); // Josephson constant (2022 CODATA) CONSTANT(mu_B, 9.274'010'0657e-24, joules_per_tesla); // Bohr magneton (symbol: µB, 2022 CODATA) CONSTANT(mu_N, 5.050'783'7393e-27, joules_per_tesla); // nuclear magneton (symbol: μ_N, 2022 CODATA)) CONSTANT(Phi_0, 2.067833848e-15, webers); // magnetic flux quantum (symbol: Φ_0) CONSTANT(R_K, 25'812.807'45, ohms); // von Klitzing constant (2022 CODATA) CONSTANT(R_Km90, 25812.807, ohms); // conventional value of von Klitzing constant // +++ ATOMIC AND NUCLEAR CONSTANTS +++ CONSTANT(a_0, 5.291'772'105'44e-11, meters); // Bohr radius (2022 CODATA) CONSTANT(alpha, 7.2973525e-3, dimensionless); // fine-structure constant CONSTANT(alpha_inv, 137.035'999'177, dimensionless); // inverse fine-structure constant (2022 CODATA) CONSTANT(E_h, 4.3597447222e-18, joules); // Hartree energy CONSTANT(g_e, -2.00231930436256, dimensionless); // electron g-factor CONSTANT(h_2me, 3.6369475e-4, meters2_per_second); // quantum of circulation CONSTANT(m_e, 9.109'383'7139e-31, kilograms); // electron mass (2022 CODATA) CONSTANT(m_d, 3.343'583'7768e-27, kilograms); // deuteron mass (2022 CODATA) CONSTANT(m_h, 5.006'412'7862e-27, kilograms); // helion mass (2022 CODATA) CONSTANT(m_mu, 1.883'531'627e-28, kilograms); // muon mass (2022 CODATA) CONSTANT(m_n, 1.674'927'500'56e-27, kilograms); // neutron mass (2022 CODATA) CONSTANT(m_p, 1.672'621'925'95e-27, kilograms); // proton mass (2022 CODATA) CONSTANT(m_tau, 3.167'54e-27, kilograms); // tau mass (2022 CODATA) CONSTANT(m_t, 5.007'356'7512e-27, kilograms); // triton mass (2022 CODATA) CONSTANT(r_e, 2.817'940'3205e-15, meters); // classical electron radius (2022 CODATA) CONSTANT(R_inf, 10'973'731.568'157, per_meter); // Rydberg constant (2022 CODATA) CONSTANT(sin2Theta_W, 0.22290, dimensionless); // weak mixing angle CONSTANT(sigma_e, 6.6524587e-29, meters2); // Thomson cross section (symbol: σ_e) // +++ PHYSICO-CHEMICAL CONSTANTS +++ CONSTANT(b, 2.897771955e-3, meter_kelvins); // Wien wavelength displacement law constant CONSTANT(c_1, 3.741771852e-16, wattmeters2); // first radiation constant CONSTANT(c_1L, 1.191042972e-16, watts_per_meter2); // first radiation constant for spectral radiance CONSTANT(F, 96'485.332'12, coulombs_per_mol); // Faraday constant (2022 CODATA) CONSTANT(m_u, 1.660'539'068'9252e-27, kilograms); // atomic mass constant (2022 CODATA) CONSTANT(M_u, 1.000'000'001'05e-3, kilograms_per_mol); // molar mass constant (2022 CODATA) CONSTANT(R, 8.314'462'618, joules_per_kelvin_per_mol); // molar gas constant (2022 CODATA) CONSTANT(R_dry_air, 287.050'0676, joules_per_kilogram_per_kelvin); // specific gas constant for dry air CONSTANT(S_0_by_R, -1.15170753706, dimensionless); // Sackur–Tetrode constant CONSTANT(V_m, 22.710'954'64e-3, meters3_per_mol); // molar volume of ideal gas (273.15K, 100kPa, 2022 CODATA) // +++ PHYSICAL CONSTANTS +++ CONSTANT(gravitational_constant,6.6743015e-11, meters3_per_kilogram_per_second2); CONSTANT(Earth_gravity, 9.80665, meters_per_second2); // standard gravitational acceleration (G) for the surface of the Earth, defined in the third General Conference on Weights and Measures (1901, CR 70). CONSTANT(speed_of_sound, 343, meters_per_second); // speed of sound in dry air at 20°C (68°F) CONSTANT(speed_of_sound_in_fresh_water, 1481, meters_per_second); // at 20°C (68°F) CONSTANT(speed_of_sound_in_iron, 5120, meters_per_second); CONSTANT(speed_of_sound_in_diamonds, 12'000, meters_per_second); // +++ MATHEMATICAL CONSTANTS +++ CONSTANT(tau, 6.28318530717958647692, radians); // (symbol: τ) CONSTANT(pi, 3.14159265358979323846, radians); // (symbol: π) CONSTANT(half_pi, 1.57079632679489661923, radians); // (π / 2) CONSTANT(quarter_pi, 0.78539816339744830961, radians); // (π / 4) CONSTANT(phi, 1.61803398874989484820, dimensionless); // (symbol: φ) CONSTANT(Eulers_number,2.71828182845904523536, dimensionless); // +++ ASTRONOMICAL CONSTANTS +++ CONSTANT(AU, 149'597'870'691, meters); // one astronomical unit (symbol: au) CONSTANT(parsec, 30'856'775'814'913'700, meters); // one Parsec (symbol: pc) CONSTANT(lightyear, 9'460'730'777'119'564, meters); // one light-year (symbol: ly) // +++ VARIOUS CONSTANTS +++ CONSTANT(T0, 0, kelvins); // absolute zero (-273.15°C, the lowest possible temperature) CONSTANT(Marathon_distance, 42'195, meters); CONSTANT(quarter_mile, 402.34, meters); #undef CONSTANT } } // namespace SI::constant // References // ---------- // 1. https://en.wikipedia.org/wiki/International_System_of_Units // 2. https://en.wikipedia.org/wiki/List_of_physical_constants // 3. https://en.wikipedia.org/wiki/List_of_mathematical_constants // 4. https://en.wikipedia.org/wiki/Astronomical_constant // 5. https://codata.org - CODATA: the committee on data of the International Science Council (ISC)