Provides models for physical quantities.

The difference between models lies in the assumptions each makes and, in consequence,the operations each permits. For example, the summation of a {@link org.jscience.physics.quantities.Length} and a {@link org.jscience.physics.quantities.Duration} is not allowed by the standard model, but is quite valid in a relativistic context.

Also, the current model specifies the default output units for physical quantities (Ref. {@link org.jscience.physics.quantities.Quantity#getOutputUnit}).

The current model is {@link javolution.realtime.LocalContext context-local}, different models can be used concurrently within the same application.

The names and characteristics of the models are presented in the following table:

Model Class Defining Characteristics Default Output Units
Standard "StandardModel" per Système Internationale LengthmMasskgDurationsElectricCurrentATemperatureKAmountOfSubstancemolLuminousIntensitycd
Relativistic "RelativisticModel" 1 = c Length, DurationsMasseVElectricCurrentATemperatureKAmountOfSubstancemolLuminousIntensitycd
High-Energy "HighEnergyModel" 1 = c
   = k
   = ePlus
Length, DurationnsMass, TemperatureGeVElectricCurrent1/nsAmountOfSubstancemolLuminousIntensitycd
Quantum "QuantumModel" 1 = c
   = k
   = µ0
   = hBar
Length, Duration1/GeVMass, Temperature, ElectricCurrentGeVAmountOfSubstancemolLuminousIntensitycd
Natural "NaturalModel" 1 = c
   = k
   = µ0
   = hBar
   = G
Length, Mass, Duration, ElectricCurrent, Temperature: 1;  AmountOfSubstancemolLuminousIntensitycd