  An interpretation of the inertial mass increase due to an object's velocity
which is derived from the theory of special relativity is discussed. A Lorentz
transformation of the reference time causes the inertial mass increase. It is
assumed that the real physical phenomenon that occurs is an expansion of the
reference time by a Lorentz transformation (that is, a dilation of time). Only
the reference time is assumed to be variant, which causes relativistic mass.
Time dilation is real. Relativistic mass originates in a Lorentz transformation
of reference time.
