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Comment by tlogan | Hacker News Reader

Can the Modified Newtonian Dynamics (MOND) theory adequately explain the Cosmic Microwave Background (CMB) radiation and the persistent mass discrepancies observed in galaxy clusters?

Furthermore, as a laiman, I'm puzzled by how certain versions of MOND requires introduction of new fields. Doesn't this effectively the same as saying there is some new particle we neeed to discover?

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MOND is really a rule without a theory; it simply posits that there is an acceleration cutoff below which gravity does not obey an inverse square law. This conjecture has been shown to have impressive predictive power, and it naturally explains a bunch of observations that are not obviously related and require fine-tuning in a dark matter paradigm. The blog linked here goes into a lot of detail on those observations, as well as observed phenomena that don't seem to fit well with MOND.

What the theory underlying MOND actually is is anyone's guess, and an area of active conjecture. But that's just as true for dark matter.

Another equally plausible MOND model is one in which the gravitational constant G increases with distance. This is what is observed in the orbits of stars around the center of a galaxy.

Of course, this is a pseudo-increase caused by, you guessed it, dark matter.

There is a relativistic MOND theory that has predicted the CMB spectrum[0]. And perhaps. MOND is first of all observational. AeST is just the latest (and AFAIK best) attempt to create a theory that reproduces the MOND acceleration artifact.

0: https://tritonstation.com/2023/01/13/what-we-have-here-is-a-...

Are you still a layman if you’re able to ask these questions though?

If you got at least halfway in to Sean Carroll’s recent 4 hour podcast on the subject — yes ;)

I thank you for this reference. Having a blast listening to him.

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