The rest energy of a particle is defined as:
- ,
where is the speed of light in a vacuum. In general, only differences in energy have physical significance.
The concept of rest energy follows from the Special theory of relativity that leads to Einstein's famous conclusion about equivalence of energy and mass. See background for mass-energy equivalence.
On the other hand, the concept of the equivalent Dirac invariant rest mass may be defined in terms of the self energy corresponding to the product of a geometric matter current and a generalized potential as part of a single definition of mass in a geometric unified theory.
Read more about this topic: Invariant Mass
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