A tale of many Hubble constants

Despite its spectacular success, the ΛCDM model is ultimately phenomenological: it establishes a robust framework in which some fundamental issues remain unresolved. With observations becoming increasingly precise, it is reasonable to expect that “something’s gotta give” and  that the ΛCDM model will show some cracks. The Hubble tension— the discrepancy between the value of the Hubble parameter, when inferred as a global parameter of the standard cosmological model , and when measured directly in the late-time Universe from the redshift-to-distance relation—  has been looming for a decade and has been studied extensively. Could it be such a crack?  I will give an overview of  the status of the Hubble tension and tentatively speculate on why it has persisted thus far.



bio:
Licia Verde is an astrophysicist with interest in cosmology. Her research topics include theoretical cosmology, cosmic microwave background, large-scale structure,  analysis of galaxy redshift surveys, statistical applications and data analysis. She is currently ICREA Professor at the Institut de Ciències del Cosmos at the Universitat de Barcelona (ICCUB).