Physics.

The speed of light in vacuum is one of the few physical constants whose value is exact by definition rather than measurement — the 1983 SI redefinition of the metre fixed it precisely, making it the ultimate speed limit for information and matter in relativity.

No heat engine operating between two temperature reservoirs can convert heat to work more efficiently than a reversible one: the Carnot limit η ≤ 1 − T_c/T_h, where T_h and T_c are the hot and cold reservoir temperatures.

Erasing one bit of information in a logically irreversible way necessarily dissipates heat into the environment — a fundamental link between information and thermodynamics. The minimum dissipated energy is Q ≥ k_B T ln(2), where T is the system's temperature.

The 2022 CODATA recommended value of alpha particle-electron mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle mass energy equivalent, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle mass energy equivalent in MeV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle mass in u, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle molar mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle-proton mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle relative atomic mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of alpha particle rms charge radius, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Angstrom star, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass constant energy equivalent, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass constant energy equivalent in MeV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic mass unit-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of 1st hyperpolarizability, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of 2nd hyperpolarizability, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of action, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of charge, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of charge density, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of current, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric dipole mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric field, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric field gradient, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric polarizability, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric potential, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of electric quadrupole mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of energy, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of force, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of length, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of mag. dipole mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of mag. flux density, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of magnetizability, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of momentum, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of permittivity, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of time, retained with its published standard uncertainty.

The 2022 CODATA recommended value of atomic unit of velocity, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Avogadro constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr magneton, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr magneton in eV/T, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr magneton in Hz/T, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr magneton in inverse meter per tesla, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr magneton in K/T, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Bohr radius, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Boltzmann constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Boltzmann constant in eV/K, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Boltzmann constant in Hz/K, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Boltzmann constant in inverse meter per kelvin, retained with its published standard uncertainty.

The 2022 CODATA recommended value of characteristic impedance of vacuum, retained with its published standard uncertainty.

The 2022 CODATA recommended value of classical electron radius, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Compton wavelength, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conductance quantum, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of ampere-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of coulomb-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of farad-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of henry-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of Josephson constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of ohm-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of volt-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of von Klitzing constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of conventional value of watt-90, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Copper x unit, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron-electron mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron-electron mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron g factor, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mag. mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mag. mom. to Bohr magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mag. mom. to nuclear magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mass energy equivalent, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mass energy equivalent in MeV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron mass in u, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron molar mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron-neutron mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron-proton mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron-proton mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron relative atomic mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of deuteron rms charge radius, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron charge to mass quotient, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-deuteron mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-deuteron mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron g factor, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron gyromag. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron gyromag. ratio in MHz/T, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-helion mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mag. mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mag. mom. anomaly, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mag. mom. to Bohr magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mag. mom. to nuclear magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mass energy equivalent, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mass energy equivalent in MeV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron mass in u, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron molar mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-muon mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-muon mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-neutron mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-neutron mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-proton mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-proton mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron relative atomic mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-tau mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron to alpha particle mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron to shielded helion mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron to shielded proton mag. mom. ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron-triton mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of electron volt-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of elementary charge, retained with its published standard uncertainty.

The 2022 CODATA recommended value of elementary charge over h-bar, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Faraday constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Fermi coupling constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of fine-structure constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of first radiation constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of first radiation constant for spectral radiance, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Hartree energy, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Hartree energy in eV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hartree-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion-electron mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion g factor, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mag. mom., retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mag. mom. to Bohr magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mag. mom. to nuclear magneton ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mass energy equivalent, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mass energy equivalent in MeV, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion mass in u, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion molar mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion-proton mass ratio, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion relative atomic mass, retained with its published standard uncertainty.

The 2022 CODATA recommended value of helion shielding shift, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hertz-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of hyperfine transition frequency of Cs-133, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse fine-structure constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse meter-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of inverse of conductance quantum, retained with its published standard uncertainty.

The 2022 CODATA recommended value of Josephson constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of joule-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kelvin-kilogram relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-atomic mass unit relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-electron volt relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-hartree relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-hertz relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-inverse meter relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-joule relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of kilogram-kelvin relationship, retained with its published standard uncertainty.

The 2022 CODATA recommended value of lattice parameter of silicon, retained with its published standard uncertainty.

The 2022 CODATA recommended value of lattice spacing of ideal Si (220), retained with its published standard uncertainty.

The 2022 CODATA recommended value of Loschmidt constant (273.15 K, 100 kPa), retained with its published standard uncertainty.

The 2022 CODATA recommended value of Loschmidt constant (273.15 K, 101.325 kPa), retained with its published standard uncertainty.

The 2022 CODATA recommended value of luminous efficacy, retained with its published standard uncertainty.

The 2022 CODATA recommended value of mag. flux quantum, retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar gas constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar mass constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar mass of carbon-12, retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar Planck constant, retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar volume of ideal gas (273.15 K, 100 kPa), retained with its published standard uncertainty.

The 2022 CODATA recommended value of molar volume of ideal gas (273.15 K, 101.325 kPa), retained with its published standard uncertainty.