Unsqueezing of standing waves due to inflationary domain structure

Understand

The so-called "trans-Planckian" problem of inflation may be evaded by positing that modes come into existence only when they became "cis-Planckian" by virtue of expansion.

• However, this would imply that for any mode a new random realization would have to be drawn every $N$ wavelengths, with $N$ typically of order 1000 (but it could be larger or smaller).
• Such a re-drawing of realizations leads to a heteroskodastic distribution if the region under observation contains several such independent domains.
• This has no effect on the sampled power spectrum for a scale-invariant raw spectrum, but at very small scales it leads to a spectral index bias towards scale-invariance and smooths oscillations in the spectrum.