  The inflationary cosmology paradigm is very successful in explaining the CMB
anisotropy to the percent level. Besides the dependence on the inflationary
model, the power spectra, spectral tilt and non-Gaussianity of the CMB
temperature fluctuations also depend on the initial state of inflation. Here,
we examine to what extent these observables are affected by our ignorance in
the initial condition for inflationary perturbations, due to unknown new
physics at a high scale $M$. For initial states that satisfy constraints from
backreaction, we find that the amplitude of the power spectra could still be
significantly altered, while the modification in bispectrum remains small. For
such initial states, $M$ has an upper bound of a few tens of $H$, with $H$
being the Hubble parameter during inflation. We show that for $M\sim 20 H$,
such initial states always (substantially) suppress the tensor to scalar ratio.
In particular we show that a general choice of initial conditions can
satisfactorily reconcile the simple $1/2 m^2 \phi^2$ chaotic model with the
Planck data.
