  The observations of SNIa suggest that we live in the acceleration epoch when
the densities of the cosmological constant term and matter are almost equal.
This leads to the cosmic coincidence conundrum. As the explanation for this
problem we propose the FRW model with dark matter and dark energy which
interact each other exchanging energy. We show that the cubic correction to the
Hubble law, measured by distant supernovae type Ia, probes this interaction. We
demonstrate that influences between nonrelativistic matter and vacuum sectors
are controlled by third and higher derivatives of the scale factor. As an
example we consider flat decaying $\Lambda(t)$ FRW cosmologies. We point out
the possibility of measure of the energy transfer by the cubic and higher
corrections to Hubble's law. The statistical analysis of SNIa data is used as
an evidence of energy transfer. We find that there were the transfer from the
dark energy sector to the dark matter one without any assumption about physics
governing this process. We confront this hypothesis about the transfer with
SNIa observations and find that the transfer the phantom and matter sector is
admissible for $\Omega_{\text{m},0}=0.27$. We also demonstrate that it is
possible to differentiate between the energy transfer model and the variable
coefficient equation of state model.
