The main claim of the paper is that data from the Planck satellite, which measures the cosmic microwave background (CMB), suggests that the universe might be closed rather than flat. This contradicts the prevailing cosmological model, which assumes a flat universe, and poses a potential crisis for current cosmological theories.
The Planck satellite provided high-precision measurements of the CMB, which showed subtle anomalies in the data. Specifically, the analysis of the CMB power spectrum indicated a slight curvature, implying that the universe might be closed and finite rather than flat and infinite.
A closed universe is one in which space is curved back on itself, much like the surface of a sphere. In such a universe, if you travel far enough in one direction, you would eventually return to your starting point. In contrast, a flat universe has no curvature, and parallel lines remain parallel indefinitely. A closed universe also implies that the total energy density of the universe is greater than the critical density needed for a flat universe.
This claim poses a crisis for cosmology because it challenges the widely accepted Lambda Cold Dark Matter (ΛCDM) model, which assumes a flat universe. The ΛCDM model has been incredibly successful in explaining a wide range of cosmological observations. If the universe is indeed closed, it would require significant revisions to our understanding of fundamental cosmological parameters and theories.
If the universe is truly closed, it would have profound implications for cosmology and our understanding of the universe's fate. It could affect calculations related to the age of the universe, the rate of its expansion, and the ultimate fate of cosmic structures. Additionally, it would necessitate a re-evaluation of many cosmological models and could lead to new physics beyond the current standard model of cosmology.