To understand SRT we need to answer to the simple question:
In which Reference frame does SRT take place?
One of the SRT postulate says – in Galileo/ Newtonian space.
The other postulate says - in the vacuum.
But the common opinion – the SRT takes place in Minkowski
absolute negative 4D.
My opinion is:
The SRT explains how quantum of light, using Lorentz
transformation, can transfer from one Reference frame –vacuum
to another Reference frame- Galileo/ Newtonian space.
And of course, according to ‘ The law of conservation and
transformation energy/ mass’ this process can go vice versa.