A New Method for Studying the Topology of the Universe from the Cosmic   Microwave Background
  The standard method for observationally confirming the existence of a predicted finite topology of the universe involves searching for the repetition of the same finite or extended source in different directions. However, serious problems are encountered when studying both types of sources, finite and extended. In studying a finite source, such as a star, galaxy, or quasar, the problem of its evolution must be dealt with. The same source seen in different directions is observed at different distances (i.e., ages), making its identification extremely difficult. Studying extended sources, such as circles-in-the-sky (CIS) within the cosmic microwave background (CMB), is also problematic since it requires an unrealistic zero width last scattering surface (LSS) to produce the predicted identical temperatures on the circles. It is shown here that these temperatures are no longer identical when a realistic finite width LSS is taken into account. A new method for studying the topology of the universe which avoids the above mentioned problems in studying both finite and extended sources is suggested here. It consists of searching for increased temperature fluctuations in the regions of the intersections of the LSS with the faces of the fundamental polyhedron of the finite topology. Appreciably greater fluctuations are predicted in these regions. A worked-out example is given. 
Reuven Opher