Louise Riofrio recently pointed out that the inflation is in a bit of trouble due to the fact that it predicts a different curve than the one seen for the angular correlation of anisotropies of the Cosmic Microwave Background (CMB). An easily understood review of the CMB is given by The Cosmic Microwave Background for Pedestrians: A Review for Particle and Nuclear Physicists, astro-ph/0803.0834. The data excludes the curve expected by inflation at well above the 99% level:
Previously, Louise had explained the anomaly in a manner that I was too obtuse to understand, for example:
Views of the Cosmic Microwave Background may also indicate a spherical Universe. By measuring distances between acoustic peaks, scientists hope to complete a triangle and determine curvature. When a changing speed of light is accounted for, the angles do not add up to 180 degrees and the triangle is not flat. Most telling, the scale of density fluctuations is nearly zero for angles greater than 60 degrees. Like a ship disappearing over Earth’s horizon, the lack of large-angle fluctuations is smoking-gun evidence that the Universe is curved. Both lines of CMB data indicate that the curvature has radius R = ct.