Based on the assumption that the experiment confirms the STR, it is
shown that the magnitude of the speed of light is an extremely slowly decreasing
function of its frequency. However, at frequencies less than 1 hertz, the speed
light begins to decrease sharply, and at a frequency of 4,6∙〖10〗^(-21) с-1, the speed
of light becomes zero. Such light could serve as the Absolute Reference System,
but due to their negligible mass, they do not have any effect on the processes
taking place. This explains the postulate of Einstein's principle of relativity. The
formulas for the change in the speed and frequency of light during the transition
from one IRS to another remain unchanged, which proves Einstein's postulate of
the constancy of the speed of light in any IRS.