from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A vector in four-dimensional vector space, especially one having three spatial and one temporal dimensions
Sorry, no etymologies found.
The expression for this action A is where where is the four-vector position of the ith particle as a function of some parameter.
It would also spoil the Lorentz invariance by itself because the entropy density is a time component of a four-vector (am entropy current) and its nonzero