Spectral Variations of the Sky: Constraints on Alternate Universes

Understand

The fine tuning of parameters required to reproduce our present day Universe suggests that our Universe may simply be a region within an eternally inflating super-region.

• Many other regions beyond our observable Universe would exist with each such region governed by a different set of physical parameters.
• Collision between these regions, if they occur, should leave signatures of anisotropy in the cosmic microwave background (CMB) but have not been seen.
• We analyze the spectral properties of masked, foreground-cleaned maps between 100 and 545 GHz constructed from the Planck dataset.