Omega Syndrome

Starring: Doug McClure, spatial curvature

Spatial curvature was completely irrelevant at z>1000, when the acoustic oscillations were created. Omega_k therefore doesn't change the shape of the peaks at all - it merely shifts them sideways, since the conversion from the physical scale of the wiggles (in meters) into the angular scale (in degrees, or multipole l) depends on whether space is curved. If space has negative curvature (positive Omega_k), like a Pringles potato chip or a saddle, then the angle subtended on the sky decreases, shifting the peaks to the right. If space has positive curvature, like a balloon, then the peaks shift to the left.
In addition to shifting the peaks sideways, curvature also causes fluctuations in the gravitational field to decrease over time. This means that if a photon flies though a potential well on the way to us, its blueshift from falling in will exceed its redshift from climbing out. Since these extra fluctuations in the photon temperature (known as the late ISW effect) happen at late times, they show up on large scales (to the left in the power spectrum).