  Maxwell equations provide a complete description of the electromagnetic (EM)
phenomena, which have been one of the key fundamental-theories of modern
physics, such as electromagnetism, optics, quantum theories, etc. The vacuum
permittivity and permeability (P&P) in the constitutive relation were regarded
as constant, resulting into that the vacuum lightspeed is constant with time.
However, neither the Maxwell equations nor any experiments demonstrated that
the P&P must be invariable with time. Here, the P&P are assumed as time-varied,
achieving a mathematical result exhibits that the P&P are increased with time
exponentially. Then, the Maxwell equations of static and covariant EM fields
are presented, which include the different constitutive relations. The EM
characters in the time-varied case are investigated that, the lightspeed, level
EM intensity, and magnetic effect of charge-motion decreases with time. The EM
energy transforms into a new energy form caused by the P&P variation, and a new
momentum-tensor form caused by propagation is found as well. At last, the
Maxwell equations based on the observation results at our time are presented.
Meanwhile, since the level EM intensity decreases with time, the energy per
frequency is time-decreased, resulting into that the Planck constant decreases
exponentially, and correspondingly, the Rydberg constant increases with time. A
red-shift of absorption spectrum is predicted based on this finding, which is
coincident with the Hubble observation results.

Classical Physics;Optics