A Fundamental Problem in Physics: (Mass vs Electric Charge)

In modern physics there exist opposite concepts regarding the constancy and the variability of two major properties of the electron: its mass and its electric charge. Section 1: Mainstream physicists consider the mass of the electron as varying with its velocity while its electric charge as a fundamental constant of physics. Section 2: On the other hand, many other physicists maintain the opposite concept: the mass of the electron is invariant in all physical conditions while its electric charge is variable. Section 3: In the case when the mass is invariant, a mathematical expression for the variability of the electric charge of the electron in external fields will be deduced. Section 4: A thought experiment to demonstrate the variability of the electric charge of the electron in a changing magnetic field. Section 5: Discussions: (1) Why is the electric charge changed in external field? 2) Renormalizing the mass is problematic 3) Renormalizing the electric charge is innovative 4) The mystery of the mass of the muon. 5) The controversial concept of time dilation.