(* List all names of CODATA physical constants so they are available for CTRL-F string search to find the canonical name used to access their properties such as uncertainty. *)
EntityValue["PhysicalConstant",{"CanonicalName"}]
Out[17]= {{AccelerationAssociatedWithCosmologicalExpansionRate},{AlphaParticleMass},{AmpereConstant},{AngstromStar},{AnimalMassScale},{AstronomicalUnit},{AtomicMassConstant},{AtomicMassConstantEnergyEquivalent},{AtomicPolarizabilityEquilibriumInternuclearDistanceProportionalityConstant},{AtomicSpecificHeatConstant},{AtomicUnitOfElectricChargeDensity},{AtomicUnitOfElectricConductance},{AtomicUnitOfElectricCurrent},{AtomicUnitOfElectricFieldStrength},{AtomicUnitOfElectricFieldStrengthGradient},{AtomicUnitOfElectricFirstHyperpolarizability},{AtomicUnitOfElectricPermittivity},{AtomicUnitOfElectricPolarizability},{AtomicUnitOfElectricPotential},{AtomicUnitOfElectricQuadrupoleMoment},{AtomicUnitOfElectricSecondHyperpolarizability},{AtomicUnitOfForce},{AtomicUnitOfFrequency},{AtomicUnitOfMagneticFlux},{AtomicUnitOfMagneticFluxDensity},{AtomicUnitOfMagneticMoment},{AtomicUnitOfMagnetizability},{AtomicUnitOfMomentum},{AtomicUnitOfPressure},{AtomicUnitOfTemperature},{AtomicUnitOfTime},{AtomicUnitOfVelocity},{AtomStructuralConstant},{AvogadroConstant},{AvogadroNumber},{BiotSavartConstant},{BlackHoleConjecturedFinalMass},{BlackHoleCriticalTemperature},{BohrMagneton},{BohrQuadrupoleMagneton},{BohrRadius},{BoltzmannConstant},{Carbon12AtomicMass},{Carbon12MolarMass},{Carbon12RelativeAtomicMass},{CeresSunMassRatio},{Cesium133HyperfineSplittingFrequency},{CirculationQuantum},{ClassicalElectronRadius},{ClassicalProtonRadius},{ConductanceQuantum},{CosmicMicrowaveBackgroundTemperature},{CosmologicalConstant},{CosmologicalNaturalLength},{CosmologicalNaturalMass},{CosmologicalNaturalTime},{CosmologicalQuantumPointEnergy},{CosmologicalQuantumPointLength},{CosmologicalQuantumPointMass},{CosmologicalRadius},{CoulombConstant},{CurieConstantSquareRootMultiplier},{DeuteronGFactor},{DeuteronMagneticMoment},{DeuteronMass},{DimensionlessHubbleParameter},{DiracMonopoleMagneticCharge},{DoubledCirculationQuantum},{EarthAuthalicRadius},{EarthEquatorialRadius},{EarthFirstEccentricity},{EarthFirstFlattening},{EarthGeomagneticReferenceRadius},{EarthInverseFlattening},{EarthLinearEccentricity},{EarthMass},{EarthMeanRadius},{EarthMeridionalRadiusOfCurvature},{EarthMoonMassRatio},{EarthPolarRadius},{EarthPolarRadiusOfCurvature},{EarthRectifyingRadius},{EarthRotationalAngularVelocity},{EarthSecondDynamicFormFactor},{EarthSecondEccentricity},{EarthSecondFlattening},{EarthThirdEccentricity},{EarthThirdFlattening},{EarthVolumetricRadius},{EddingtonConstant4},{EddingtonNumber},{EinsteinConstantSpeedOfLightSquared},{EinsteinConstantSpeedOfLightToTheFourth},{ElectricBohrDipoleMoment},{ElectricBohrQuadrupoleMoment},{ElectricConstant},{ElectromagneticCouplingConstant},{ElectromagneticInteractionStrengthAtZBosonMass},{ElectronAbsoluteMass},{ElectronChargeMassRatio},{ElectronComptonFrequency},{ElectronComptonWavelength},{ElectronGFactor},{ElectronGFactorAbsoluteValue},{ElectronGyromagneticRatio},{ElectronMagneticMoment},{ElectronMagneticMomentAnomaly},{ElectronMass},{ElectronMolarMass},{ElectronProtonElectricGravitationalForceRatio},{ElectronProtonMassRatio},{ElectronReducedGyromagneticRatio},{ElectronRelativeAtomicMass},{ElectronSchroedingerConstant},{ElectronSchroedingerSquareRootConstant},{ElectronWaveMass},{ElectroweakGravityCoupledMaximumCutoffEnergyScale},{ElementaryCharge},{FaradayConstant},{FermiCouplingConstant},{FineStructureConstant},{FirstEddingtonNumber},{FirstFowlerNordheimConstant},{FirstRadiationConstant},{FirstRadiationConstantForSpectralRadiance},{FixedNucleusAtomSchroedingerConstant},{FundamentalKinematicViscosity},{GalacticMassScale},{GalacticUnit},{GaussianGravitationalConstant},{GeneralRelativityMaximalForce},{GeneralRelativityMaximalPower},{GeometryActionQuantum},{GravitationalConstant},{GravitationalConstantPerSpeedOfLightSquared},{GravitationalCouplingConstantElectronElectron},{GravitationalCouplingConstantElectronProton},{GravitationalFineStructureConstant},{GravitationalPermeability},{HartreeEnergy},{HBarCProduct},{HCProduct},{HelionGFactor},{HertzKelvinRelationship},{HiggsBosonMass},{HiggsVacuumExpectationValue},{HorizonMassScaleAtEquality},{HubbleLength},{HubbleParameter},{HubbleTime},{HubbleVolume},{HydrogenAtomGroundStateLinearChargeDensity},{HydrogenAtomSchroedingerConstant},{IdealGasMolarVolume},{ImagePotentialEnergyConstant},{InternationalAnnealedCopperStandard},{InvariantSlowness},{InverseConductanceQuantum},{InverseFineStructureConstant},{InverseSquareRootElectricConstant},{JeansMassScaleAtEquality},{JordanNumber1},{JordanNumber2},{JordanNumber3},{JosephsonConstant},{JovianMassParameter},{JupiterEquatorialRadius},{JupiterPolarRadius},{KovtunSonStarinetBound},{LifeFormChemicalConversionFactor},{LorentzConstant},{LorentzUnit},{LorenzNumber},{LoschmidtConstant},{MagneticConstant},{MagneticCoulombConstant},{MagneticCouplingConstant},{MagneticFineStructureConstant},{MagneticFluxQuantum},{MaximumAtomicNumber},{MaximumNeutronStarMassScale},{MaximumStarRadiusSchwarzschildRadiusRatio},{MeanSolarIrradiance},{MillimagneticFluxQuantum},{MinimumNeutronStarMassScale},{MinimumOpacityLimitedFragmentMassScale},{MinimumStellarMassScale},{MolarGasConstant},{MolarMassConstant},{MolarPlanckConstant},{MONDConstant},{MONDLength},{MonochromaticRadiation540THzLuminousEfficacy},{MoonEarthMassRatio},{MuonComptonWavelength},{MuonGFactor},{MuonMagneticMoment},{MuonMass},{NaturalUnitOfEnergy},{NaturalUnitOfLength},{NaturalUnitOfMomentum},{NaturalUnitOfTime},{NeutronComptonWavelength},{NeutronGFactor},{NeutronGyromagneticRatio},{NeutronMagneticMoment},{NeutronMass},{NeutronReducedGyromagneticRatio},{NeutronStarMaximumAngularMomentum},{NonlinearQEDEffectsOnsetElectromagneticEnergyDensity},{NuclearMagneton},{ObservableUniverseMaximumAngularMomentum},{PallasSunMassRatio},{Parsecs},{PermeabilityRationalizationConstant},{PermittivityRationalizationConstant},{PhotonPhotonCrossSectionUpperLimit},{PiPlusOrMinusMass},{PiZeroMass},{PlanckArea},{PlanckConstant},{PlanckFrequency},{PlanckLength},{PlanckMass},{PlanckMassDensity},{PlanckTemperature},{PlanckTime},{PlanckVolume},{PlanetaryMassScale},{ProtonComptonWavelength},{ProtonElectronMassRatio},{ProtonElementaryViscosity},{ProtonGFactor},{ProtonGyromagneticRatio},{ProtonMagneticMoment},{ProtonMass},{ProtonMolarMass},{ProtonProtonElectricGravitationalForceRatio},{ProtonReducedGyromagneticRatio},{ProtonRelativeAtomicMass},{ProtonRMSChargeRadius},{QCDScale},{QEDEulerHeisenbergLagrangianPrefactor},{QuadraticHiggsCoefficient},{QuantizedHallConductance},{QuantumChannelThermalConductanceConstant},{QuantumJumpCharacteristicDecayTime},{QuarticHiggsCoefficient},{RadiationConstant},{ReducedBohrRadius},{ReducedFermiConstant},{ReducedPlanckConstant},{ReducedPlanckMass},{RelativisticBohrRadius},{RelativisticReducedPlanckMass},{RichardsonDushmanConstant},{RydbergConstant},{RydbergConstantHydrogen},{RydbergEnergy},{RydbergFrequency},{RydbergWavelength},{SackurTetrodeConstant},{SchottkyConstant},{SchwingerElectricFieldStrength},{SchwingerMagneticFluxDensity},{SecondEddingtonNumber},{SecondFowlerNordheimConstant},{SecondRadiationConstant},{ShemiZadehNumber},{ShemiZadehNumberB0},{SignedElementaryCharge},{Silicon220LatticeSpacing},{SiliconMolarVolume},{SolarConstant},{SolarEffectiveTemperature},{SolarLuminosity},{SolarMass},{SolarMassParameter},{SolarRadius},{SolarSchwarzschildRadius},{SommerfeldSupplyDensityConstant},{SpacetimeAtomAvogadroNumber},{SpeedOfLight},{SpeedOfSound},{SpeedOfSoundCondensedPhaseUpperBound},{StandardAccelerationOfGravity},{StandardAtmosphere},{StandardConcentration},{StandardMolality},{StandardPressure},{StandardStatePressure},{StefanBoltzmannConstant},{StellarMassScale},{StrongCouplingConstant},{StrongInteractionStrengthAtZBosonMass},{SunEarthMassRatio},{SunErisMassRatio},{SunJupiterMassRatio},{SunMarsMassRatio},{SunMercuryMassRatio},{SunNeptuneMassRatio},{SunPlutoMassRatio},{SunSaturnMassRatio},{SunUranusMassRatio},{SunVenusMassRatio},{TauComptonWavelength},{TauMass},{TerrestrialMassParameter},{ThompsonLampardCalculableCapacitorCapacitance},{ThomsonCrossSection},{TotalSolarIrradiance},{TwoSpeciesApproximateSingleDensityNonNeutralFailedWhiteDwarfRadius},{UniversalPhotogalvanicConstant},{UniverseAge},{UniverseAtomCount},{UniverseBaryonCount},{UniverseBaryonicMatterDensityParameter},{UniverseBaryonicMatterMassDensity},{UniverseBindingEnergyMassEnergyEquivalentRatio},{UniverseColdDarkMatterDensityParameter},{UniverseColdDarkMatterMass},{UniverseColdDarkMatterMassDensity},{UniverseCriticalMassDensity},{UniverseDarkEnergyDensityParameter},{UniverseDarkEnergyMassDensity},{UniverseDensityParameter},{UniverseDiameter},{UniverseDimensionlessBaryonPhotonRatio},{UniverseElectronCount},{UniverseEntropy},{UniverseMass},{UniverseMassDensity},{UniverseNeutrinoDensityParameter},{UniverseNeutronCount},{UniverseNucleonCount},{UniverseParticleCount},{UniversePressurelessMatterDensityParameter},{UniversePressurelessMatterMassDensity},{UniverseProtonCount},{UniverseRadius},{UniverseVacuumEnergyDensity},{UniverseVacuumEnergyDensityEnergyScale},{UniverseVolume},{VacuumDominatedUniverseMassScale},{VacuumImpedance},{VestaSunMassRatio},{VonKlitzingConstant},{WaterFreezingTemperature},{WaterTriplePointTemperature},{WBosonMass},{WeakHyperchargeCouplingConstant},{WeakInteractionStrengthAtZBosonMass},{WeakIsospinCouplingConstant},{WeakMixingAngleConstant},{WeinbergAngle},{WienFrequencyDisplacementLawConstant},{WienWavelengthDisplacementLawConstant},{YukawaBottomQuarkCouplingConstant},{YukawaCharmQuarkCouplingConstant},{YukawaDownQuarkCouplingConstant},{YukawaElectronCouplingConstant},{YukawaMuonCouplingConstant},{YukawaStrangeQuarkCouplingConstant},{YukawaTauonCouplingConstant},{YukawaTopQuarkCouplingConstant},{YukawaUpQuarkCouplingConstant},{ZBosonMass}}
In[18]:= (* Look up CODATA quantity given canonical name and return its uncertain value. *)
codata[canonicalName_]:= Around@@Entity["PhysicalConstant",canonicalName][{"Value","StandardUncertainty"}]
In[20]:= codata["ProtonMass"]
Out[20]= (1.672621923\[NegativeVeryThinSpace]\[NegativeVeryThinSpace]\[NegativeVeryThinSpace](7\[NegativeThinSpace]\[PlusMinus]\[NegativeThinSpace]5\[NegativeVeryThinSpace])*10^-27)kg