Comment on vibes-based astrophysics

• _different_username@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

  You might consider reading Accelerated Structure Formation: The Early Emergence of Massive Galaxies and Clusters of Galaxies. The paper is absolutely wonderful. The main thesis of the paper is, “Wow, the James Webb Telescope sure has been finding some remarkably mature galaxies for the early universe. Maybe we should consider the possibility that the models we use to predict galaxy formation, specifically lambda CDM, are incorrect and Non-Physical.”

  The author states the difficulty in the conclusion:

  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 provide a satisfactory explanation of the many phenomena that were predicted by MOND, nor is it clear that it can do so. We find ourselves caught between two very different theories that seem irreconcilable despite applying to closely related yet incommensurate lines of evidence.

  The complaints about the early maturation of galaxies seen by the JWST was widely reported. My favorite line from that article:

  “Maybe in the early universe, galaxies were better at turning gas into stars,” Chworowsky said.

  Sure, it’s not that our theories of cosmology are incorrect; things like star formation were just different back in the early universe. I guess you just had to be there.

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  • BB84@mander.xyz ⁨3⁩ ⁨weeks⁩ ago

    I’m still far from convinced about MOND. But I guess now I’m less confident in lambda CDM too -_-

    I’m inclined to believe it’s one or many of the potential explanations in your second link. But even then, those explanations are mostly postdictions so they hold less weight.

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    • porl@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

      I love the idea of MOND but it does seem like evidence is not in its favour overall. I remember getting an (I think) Scientific American magazine that featured it and I thought the idea sounded awesome. Unfortunately the universe doesn’t care what we think haha

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      • _different_username@lemmy.world ⁨2⁩ ⁨weeks⁩ ago

        Did the SA article come out before or after the article above? Because the JWST has been creating problems for lambda CDM. Take, for example, this Quanta Magazine article. The purport of the article is that, even though the data from the JWST seems to contradict ΛCDM, it really doesn’t, if we just apply post-hoc modifications.

        Why are the galaxies so bright at very high red shifts? Oh, the initial mass function was higher. Or it was super efficient star formation. Or the density of dark matter was higher in the early universe. Or the density of dark energy was higher, so the universe actually wasn’t that young after all. Or a linear combination of these things, and maybe a few others, that we can fit to the data. You don’t reconsider old theories in the light of new data, just apply more terms so that the old theory matches the new data.

        For me, if the data starts to deviate from my model, it probably means that I need a different model

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    • _different_username@lemmy.world ⁨3⁩ ⁨weeks⁩ ago

      To which McGaugh et al. had this delicious reply:

      One does not simply turn all the available baryons into stars.

      Image

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• yozul@beehaw.org ⁨3⁩ ⁨weeks⁩ ago

  MOND isn’t even a great way to explain rotation curves. It’s pretty easy to make a pretty close model for the majority of galaxies, but there are a lot of weird outliers where it’s pretty easy to say they just have more or less dark matter than usual, but MOND has a really hard time explaining them without making it so that physics works differently in different galaxies.

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  • BB84@mander.xyz ⁨3⁩ ⁨weeks⁩ ago

    I must admit I don’t know that much about MOND being tested. But yeah, from a Lambda CDM point of view it is unsurprising that MOND would not work well for every galaxy.

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