As I said above, physics is two things, equations and measurement. You don't seem to have taken this on board or tried to convince me I'm wrong.
Equations mean the constants (such as the speed of light in vacuo) must have exact values; measurement means dealing with precision and accuracy.
An electron has an exact amount of mass, etc.
The equations are a mathematical model. You claim they are exact reality, but of course that is a metaphysical position with considerable evidence against it. Equations are historically contingent and always subject to revision.