Galaxies
According to measurements of the Cosmic Microwave Background (CMB) by the Planck mission, the age of the universe is 13.8 billion years. However, new measurements of the motions of pairs of galaxies contradict the simulations based on the Standard Model of cosmology.
The Standard Model and Large-Scale Structure
The Standard Model of cosmology describes a flat universe dominated by dark energy and dark matter. Based on this model, supercomputer simulations are used to depict the growth of large-scale structure in the form of galaxies, galaxy clusters, and more.
However, recent measurements of galaxy pair motions don't match up with the predictions of these simulations. This indicates a discrepancy between the Standard Model and observations.
These inconsistencies present new challenges in understanding the formation and evolution of galaxies.
The Hubble Constant Paradox
The Hubble constant, which determines the expansion rate of the universe, has been measured using different methods. One measurement comes from the Cosmic Microwave Background and gives an age of 13.8 billion years for the universe.
Another measurement is derived from the observations of Type Ia supernovae and gives an age of 12.6 billion years. These two measurements differ significantly, leading to what is known as the "Hubble tension."
Resolving this tension is crucial for refining our understanding of the universe's age and evolution.
Challenges and Future Research
Lowering the age of the universe too much would present challenges in explaining the existence of known ancient stars and globular clusters.
Further research is needed to reconcile the discrepancies between observations and simulations and to refine our understanding of the physical processes that govern the formation and evolution of galaxies.
Studying the motions of galaxies and improving our measurements of the Hubble constant are key areas of investigation in cosmology and astrophysics.
