MOND

 is the German word for moon, but it stands here for Modified Newtonian Dynamics, a theory that gets rid of Dark Matter.

Remember, Dark Matter was introduced in astrophysics to save Einstein’s theory of General Relativity. 

The Lambda Cold Dark Matter, or ΛCDM model, is the accepted (standard) mathematical model of the Big Bang theory.

So far, nobody has observed CDM. So wouldn’t it be nice to get rid of it?

New data collected by NASA’s James Webb Space Telescope (JWST) conflicts with predictions based on ΛCDM and instead confirms predictions made with MOND. 

The James Webb Space Telescope looked deep into space and detected inexplicably big and bright galaxies in the early universe, i.e., shortly after the Big Bang.

According to the ΛCDM standard model of galaxy formation, the JWST should only find signs of small, primitive galaxies there. Bigger galaxies should form slowly by merging with smaller ones. 

But the opposite is true - large and bright galaxies are repeatedly discovered. Dark matter fails on galaxies that are “too big” or “too old.” Here, MOND comes in.

Click to enlarge

In a paper that just appeared, a research team from Case Western Reserve University in Cleveland gives an excellent summary of the present situation, and it doesn’t look good for dark matter at all. 

Sabine Hossenfelder was quick with her explanatory video about the recent paper and MOND.

The recent observations of galaxies.
They are on the blue lines, as predicted by MOND.

According to Newton and Einstein, forces decrease quadratically with distance, while the 1/r dependence in MOND speeds up the formation of galaxies. 

 At the end of their paper, the authors make some dazzling remarks:  

A number of puzzling observations in cosmology were anticipated by MOND, including the early formation of massive galaxies. 

Despite the predictive successes of MOND, we do not yet know how to construct a cosmology based on it. In contrast, ΛCDM provides a good fit to a wide range of cosmological observables but does not satisfactorily explain the many phenomena that were predicted by MOND. 

We find ourselves caught between two very different theories that seem irreconcilable despite applying to closely related yet incommensurate lines of evidence. The simple force law hypothesized by MOND has made enough successful prior predictions that it cannot be an accident; it must be telling us something. What that is remains as mysterious as the composition of dark matter. 

 As the Bavarians use to say, “Nichts Genaues weiß man nicht*.” 

*Nothing exact is known
*