PhysicalConstants`
As of Version 9, the new units framework can be used via Quantity in place of the PhysicalConstants`package.
The PhysicalConstants` package provided a selection of commonly used values for units or special numbers, found in various scientific fields. The units framework provided by Quantity replaces these completely.
| PhysicalConstants` | Version 9 |
| AccelerationDueToGravity | Quantity["StandardAccelerationOfGravity"] |
| AgeOfUniverse | Quantity["UniverseAge"] |
| AvogadroConstant | Quantity["AvogadroConstant"] |
| BohrRadius | Quantity["BohrRadius"] |
| BoltzmannConstant | Quantity["BoltzmannConstant"] |
| ClassicalElectronRadius | Quantity["ClassicalElectronRadius"] |
| DeuteronMagneticMoment | Quantity["DeuteronMagneticMoment"] |
| DeuteronMass | Quantity["DeuteronMass"] |
| EarthMass | Quantity["EarthMass"] |
| EarthRadius | Quantity["EarthEquatorialRadius"] |
| ElectronCharge | Quantity["ElementaryCharge"] |
| ElectronComptonWavelength | Quantity["ElectronComptonWavelength"] |
| ElectronGFactor | Quantity["ElectronGFactor"] |
| ElectronMagneticMoment | Quantity["ElectronMagneticMoment"] |
| ElectronMass | Quantity["ElectronMass"] |
| FaradayConstant | Quantity["FaradayConstant"] |
| FineStructureConstant | Quantity["FineStructureConstant"] |
| GalacticUnit | Quantity["GalacticUnit"] |
| GravitationalConstant | Quantity["GravitationalConstant"] |
| HubbleConstant | Quantity["HubbleConstant"] |
| MagneticFluxQuantum | Quantity["MagneticFluxQuantum"] |
| MolarGasConstant | Quantity["MolarGasConstant"] |
| MolarVolume | Quantity["IdealGasMolarVolume"] |
| MuonGFactor | Quantity["MuonGFactor"] |
| MuonMagneticMoment | Quantity["MuonMagneticMoment"] |
| MuonMass | Quantity["MuonMass"] |
| NeutronComptonWavelength | Quantity["NeutronComptonWavelength"] |
| NeutronMagneticMoment | Quantity["NeutronMagneticMoment"] |
| NeutronMass | Quantity["NeutronMass"] |
| PlanckConstant | Quantity["PlanckConstant"] |
| PlanckConstantReduced | Quantity["ReducedPlanckConstant"] |
| PlanckMass | Quantity["PlanckMass"] |
| ProtonComptonWavelength | Quantity["ProtonComptonWavelength"] |
| ProtonMagneticMoment | Quantity["ProtonMagneticMoment"] |
| ProtonMass | Quantity["ProtonMass"] |
| QuantizedHallConductance | Quantity["QuantizedHallConductance"] |
| RydbergConstant | Quantity["RydbergConstant"] |
| SackurTetrodeConstant | Quantity["SackurTetrodeConstant"] |
| SolarConstant | Quantity["SolarConstant"] |
| SolarLuminosity | Quantity["SolarLuminosity"] |
| SolarRadius | Quantity["SolarRadius"] |
| SolarSchwarzschildRadius | Quantity["SolarSchwarzschildRadius"] |
| SpeedOfLight | Quantity["SpeedOfLight"] |
| SpeedOfSound | Quantity["SpeedOfSound"] |
| StefanConstant | Quantity["StefanBoltzmannConstant"] |
| ThomsonCrossSection | Quantity["ThomsonCrossSection"] |
| VacuumPermeability | Quantity["MagneticConstant"] |
| VacuumPermittivity | Quantity["ElectricConstant"] |
| WeakMixingAngle | Quantity["WeakMixingAngleConstant"] |
All the previous constants are given as fundamental units in the new system. Functions such as UnitConvert can be used to find other representations of the values.
The previous names are canonical, but other forms can be found by using Quantity. There are equivalents for all the contents of the PhysicalConstants` package, and many more beyond that.
| PhysicalConstants` | Units for use with UnitConvert |
| AccelerationDueToGravity | "Meters"/"Seconds"^2 |
| AgeOfUniverse | "Seconds" |
| AvogadroConstant | 1/"Moles" |
| BohrRadius | "Meters" |
| BoltzmannConstant | "Joules"/"Kelvins" |
| ClassicalElectronRadius | "Meters" |
| CosmicBackgroundTemperature | "Kelvins" |
| DeuteronMagneticMoment | "Joules"/"Teslas" |
| DeuteronMass | "Kilograms" |
| EarthMass | "Kilograms" |
| EarthRadius | "Meters" |
| ElectronCharge | "Coulombs" |
| ElectronComptonWavelength | "Meters" |
| ElectronGFactor | 1 |
| ElectronMagneticMoment | "Joules"/"Teslas" |
| ElectronMass | "Kilograms" |
| FaradayConstant | "Coulombs"/"Moles" |
| FineStructureConstant | 1 |
| GalacticUnit | "Meters" |
| GravitationalConstant | ("Meters"^2 "Newtons")/"Kilograms"^2 |
| HubbleConstant | 1/"Seconds" |
| IcePoint | "Kelvins" |
| MagneticFluxQuantum | "Webers" |
| MolarGasConstant | "Joules"/("Kelvins" "Moles") |
| MolarVolume | "Meters"^3/"Moles" |
| MuonGFactor | 1 |
| MuonMagneticMoment | "Joules"/"Teslas" |
| MuonMass | "Kilograms" |
| NeutronComptonWavelength | "Meters" |
| NeutronMagneticMoment | "Joules"/"Teslas" |
| NeutronMass | "Kilograms" |
| PlanckConstant | "Joules" "Seconds" |
| PlanckConstantReduced | "Joules" "Seconds" |
| PlanckMass | "Kilograms" |
| ProtonComptonWavelength | "Meters" |
| ProtonMagneticMoment | "Joules"/"Teslas" |
| ProtonMass | "Kilograms" |
| QuantizedHallConductance | "Amperes"/"Volts" |
| RydbergConstant | 1/"Meters" |
| SackurTetrodeConstant | 1 |
| SolarConstant | "Watts"/"Meters"^2 |
| SolarLuminosity | "Watts" |
| SolarRadius | "Meters" |
| SolarSchwarzschildRadius | "Meters" |
| SpeedOfLight | "Meters"/"Seconds" |
| SpeedOfSound | "Meters"/"Seconds" |
| StefanConstant | "Watts"/("Kelvins"^4 "Meters"^2) |
| ThomsonCrossSection | "Meters"^2 |
| VacuumPermeability | ("Seconds" "Volts")/("Amperes" "Meters") |
| VacuumPermittivity | ("Amperes" "Seconds")/("Meters" "Volts") |
| WeakMixingAngle | 1 |
Generally, UnitConvert can be used to convert the constants to equivalent numerical values. The previous table is provided to allow derivation of numeric values and units that parallel the Version 9 package.
Note especially that the units in the kernel are expressed as strings in plural form.
Unitless forms can be derived with 1 as the unit.
Some of the values from the previous conversions will be slightly different from the old package. In some cases, this is the result of updated scientific research. (The Hubble constant can be considered an example of this.) In others, a slightly different standard was used for deriving the value, as in the case of the speed of sound in air. Finally, the so-called solar constant (and associated solar luminosity) provides an exception, as it is not in fact constant, and the current value more correctly reflects the solar cycle.