Silent initial conditions for cosmological perturbations with a change
  of space-time signature
  Recent calculations in loop quantum cosmology suggest that a transition from
a Lorentzian to an Euclidean space-time might take place in the very early
Universe. The transition point leads to a state of silence, characterized by a
vanishing speed of light. This behavior can be interpreted as a decoupling of
different space points, similar to the one characterizing the BKL phase.
  In this study, we address the issue of imposing initial conditions for the
cosmological perturbations at the transition point between the Lorentzian and
Euclidean phases. Motivated by the decoupling of space points, initial
conditions characterized by a lack of correlations are investigated. We show
that the "white noise" gains some support from analysis of the vacuum state in
the deep Euclidean regime.
  Furthermore, the possibility of imposing the silent initial conditions at the
trans-Planckian surface, characterized by a vanishing speed for the propagation
of modes with wavelengths of the order of the Planck length, is studied. Such
initial conditions might result from a loop-deformations of the Poincar\'e
algebra. The conversion of the silent initial power spectrum to a
scale-invariant one is also examined.
