The Status of Cosmic Topology after Planck Data

Understand

In the last decade, the study of the overall shape of the universe, called Cosmic Topology, has become testable by astronomical observations, especially the data from the Cosmic Microwave Background (hereafter CMB) obtained by WMAP and Planck telescopes.

• Cosmic Topology involves both global topological features and more local geometrical properties such as curvature.
• It deals with questions such as whether space is finite or infinite, simply-connected or multi-connected, and smaller or greater than its observable counterpart.
• A striking feature of some relativistic, multi-connected small universe models is to create multiples images of faraway cosmic sources.