< 0.2%!) for the age of the Universe in the standard 6-parameter dark energy + cold dark matter (LCDM) model, but faster expansion would be an extension to this model and would require an age of closer to 12.8 or 13.0 billion years. This is one tangible example. [The] structure would also grow faster, somewhat paradoxically, because we’d require extra matter to ‘balance out’ that early expansion and this would help promote earlier growth of galaxies (perhaps matching JWST observations better).

Early data from the James Webb Space Telescope (JWST) have revealed a bevy of high-redshift galaxy candidates with unexpectedly high stellar masses. An immediate concern is the consistency of these candidates with galaxy formation in the standard ΛCDM cosmological model, wherein the stellar mass (M⋆) of a galaxy is limited by the available baryonic reservoir of its host dark matter halo. The mass function of dark matter haloes therefore imposes an absolute upper limit on the number density n (>M⋆, z) and stellar mass density ρ⋆ (>