Note 1 to entry: Special theory of relativity is using the flat space-time described as example in IEV 113-07-61.

Note 2 to entry: Special theory of relativity describes mechanics and electrodynamics consistently and is the basic frame for the quantum theory of particles and fields. Gravity cannot be described by STR consistently, but by the general theory of relativity.

Note 3 to entry: Special theory of relativity is based on the following two principles.

1. Any two inertial frames are fully equivalent so there is no preferred or “absolute” one.
2. Speed of light in vacuum $c_0$ has the same value in any inertial frame in a flat space-time.

Note 4 to entry: Usually, one inertial frame, S, arbitrarily chosen, is called the “rest frame”. Another frame, S′, is moving towards S with velocity $\overrightarrow{v}$. Symbols with a prime refer to quantities measured in the moving reference frame S′, and symbols without a prime refer to quantities measured in the rest frame S. Frame S is moving toward S′ with velocity ${\overrightarrow{v}}^{\prime }=-\overrightarrow{v}$.

Note 5 to entry: Classical physics can be considered as a limit of STR, assuming $c_0\to \infty$.