# Physics Package

The physics package contains the following sub-packages:

- Particles
- Quantum
- Relativity

### Interface descriptions

#### PhysicalConstants

This interface defines often used physical constants, in SI units.

### Particles

This package contains classes that represent the fundamental particles. These are a useful source of data for quantities such as particle rest masses.

### Quantum

The quantum package distinguishes between abstract Hilbert space objects and the representations of those objects. The abstract side is encapsulated by operator classes, and the Dirac bra and ket vector classes. The representations use the standard JSci.maths matrix and vector classes. There are methods for switching between the two treatments but representations can only operate on representations and abstracts can only operate on abstracts.

### Relativity

This is based on index-free notation (differential geometry).

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