  By-now photons are the unique universal messengers. Cosmological sources like
far-away galaxies or quasars are well-known light-emitters. Here we demonstrate
that the nonlinear electrodynamics (NLED) description of photon propagation
through the weak background intergalactic magnetic fields modifies in a
fundamental way the cosmological redshift that a direct computation within a
specific cosmological model can abscribe to a distant source. Independently of
the class of NLED Lagrangian, the effective redshift turns out to be $1 +
\tilde{z} = (1 + z) \Delta$, where $\Delta \equiv (1 + \Phi_e)/(1 + \Phi_o)$,
with $\Phi \equiv {8}/{3} ({L_{FF}}/{L_F}) B^2$, being $L_F = {dL}/{dF}$,
$L_{FF} = {d^2L}/{dF^2}$, the field $F\equiv F_{\alpha \beta} F^{\alpha
\beta}$, and $B$ the magnetic field strength. Thus the effective redshift is
always much higher then the standard redshift, but recovers such limit when the
NLED correction $\Delta(\Phi_e, \Phi_o) \longrightarrow 1$. This result may
provide a physical foundation for the current observation-inspired
interpretation that the universe undergoes an accelerate expansion. However,
under the situation analyzed here, for any NLED the actual (spatial) position
of the light-emitting far-away source remains untouched.
