  In the recently proposed cosmological constant (CC) filter mechanism based on
modified gravity in the Palatini formalism, gravity in the radiation, matter
and late-time de Sitter eras is insensitive to energy sources with the equation
of state -1. This implies that finite vacuum energy shifts from phase
transitions are filtered out, too. In this work we investigate the CC filter
model at very early times. We find that the initial big bang singularity is
replaced by a cosmic bounce, where the matter energy density and the curvature
are finite. In a certain case this finiteness can be observed already on the
algebraic level.
