MOND Was Right, ΛCDM Was Very Wrong, Re When Galaxies Formed

Stacy McGaugh takes a moment to emphasize that when it comes to the timing of galaxy formation, MOND was right and the ΛCDM model was profoundly wrong.

Our paper on massive galaxies at high redshift is out in the Astrophysical Journal today. This is a scientific analysis of the JWST data that has accumulated to date as it pertains to testing galaxy formation as hypothesized by LCDM and MOND. That massive galaxies are observed to form early (z > 10) corroborates the long standing prediction of MOND, going back to Sanders (1998):

Objects of galaxy mass are the first virialized objects to form (by z=10), and larger structure develops rapidly

The contemporaneous LCDM prediction from Mo, Mao, & White (1998) – a touchstone of galaxy formation theory with nearly 2,000 citations – was

present-day disc [galaxies] were assembled recently (at z<=1).

This is not what JWST sees, as morphologically mature spiral galaxies are present to at least z = 6 (Ferreira et al 2024). More generally, LCDM was predicted to take a long time to build up the stellar mass of large galaxies, with the median time to reach half the final stellar mass being about half a Hubble time (seven billion years, give or take). In contrast, JWST has now observed many galaxies that meet this benchmark in the first billion years. That was not expected to happen.

From here.

As an aside, I strongly favor naming the critical acceleration of MOND, usually notated a₀, Milgrom's Constant, after Mordehai Milgrom, who devised MOND in 1983.