Is ΛCDM in trouble? Not yet. But it is certainly under stress. The framework is so successful that it would be foolish to abandon it for minor anomalies. However, the persistence and growing significance of the Hubble tension suggest we are not dealing with mere noise.
ΛCDM remains the best description of our universe’s history from one-trillionth of a second after the Big Bang to today. But like the epicycles of Ptolemaic astronomy, its increasing complexity (adding parameters to fix each tension) suggests it may be an approximation to a deeper theory. Cosmology is no longer a purely observational science; it is a high-stakes laboratory for fundamental physics. Whether ΛCDM survives or falls, we are living through a revolution in our understanding of the cosmos. cosmology
Introduction: The Unlikely Success of a Dark Universe Is ΛCDM in trouble