ABSTRACT For a century, hypothesis of a variable time is laid down by the
Relativity Theory. This hypothesis can explain many Nature observations,
experiments and formulas, for example the Lorentz factor demonstration. Because
of such good explanations, the hypothesis of a variable time has been
validated. Nevertheless, it remains some paradoxes and some predictions which
are difficult to measure, as a reversible time or the time variation itself.
The purpose of this article is to study another hypothesis. If it gives interesting
results, it would mean that this alternative hypothesis can also be validated.
The idea in this paper is to replace the variable time by a variable inertial
mass. To the difference with the Theory of Relativity (where the inertial mass
and the gravitational mass are equal and variable), the gravitational mass is here
supposed to be constant. So, starting from the definition of the kinetic
energy, it is introduced the Lorentz factor. And then it is demonstrated the
value of the Lorentz factor thanks to a variable inertial mass. This variable
inertial mass can also explain experiments, like Bertozzi experiment. If this
alternative demonstration was validated, it could help to open doors, other
physical effects could be explained like the addition of velocities.