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> No cosmological theory tries to explain why each star is in its exact observed location. Nice strawman. > Note that this is not the case for Milgromian theo

> No cosmological theory tries to explain why each star is in its exact observed location. Nice strawman. > Note that this is not the case for Milgromian theories. So far, no one has managed to create a theory without dark matter that can achieve this. LCDM also fails at this (see Dwarf galaxy problem, for one example), so this is not a point in your favour. > It's just that dark matter is a very simple paradigm that explains a huge number of phenomena with only a handful of free variables, and none of the alternatives work so far. LCDM doesn't work that great either. See the review I linked.

DiogenesKynikos 4y ago
> see Dwarf galaxy problem, for one example I assume you're referring to the "missing satellites problem." This problem is already essentially solved: 1. Newer, more sensitive surveys have detected more Milky Way satellite galaxies. 2. Reionization and supernova feedback quench star formation in small dark matter halos, meaning that the smallest dark matter halos never form galaxies. > See the review I linked. I think we've talked about this elsewhere on HN before, and I pointed out that the paper you're linking to gets a lot of things wrong and is published in an obscure journal (presumably because it wouldn't survive peer review at any of the major journals).
- naasking 4y ago
  > This problem is already essentially solved: "Essentially solved" is at best a euphemism for "we speculate that this will solve it". Hardly conclusive. > I think we've talked about this elsewhere on HN before, and I pointed out that the paper you're linking to gets a lot of things wrong and is published in an obscure journal (presumably because it wouldn't survive peer review at any of the major journals). A random HN comment claiming that a paper "gets a lot of things wrong" is not more convincing than the published paper itself. If you have an actual published paper or other review that addresses those points, then please point that out. Speculating as to why they published in an "obscure journal" can be explained by poor quality of the work, but it can also be explained by rampant disinterest in challenging orthodoxy, which also has a documented history of happening. Edit: to be clear, I'm not agreeing with the authors that MOND should be favoured given the evidence, but I disagree with your apparent position that MOND should be disfavoured and that LCDM is largely unproblematic.
  - DiogenesKynikos 4y ago
    > "Essentially solved" is at best a euphemism for "we speculate that this will solve it". Hardly conclusive. No, it means that it's actually been solved. If you compare the theoretically predicted number of satellite galaxies to the observed number, there's no discrepancy any more. There was a discrepancy a decade ago. There isn't any more, both because of better observations (which detect more faint galaxies) and because of better understanding of the consequences of LCDM (in particular, how reionization and supernova feedback affect star formation in low-mass galaxies). > rampant disinterest in challenging orthodoxy That's just not the case. There's huge interest in challenging orthodoxy. If there were a MOND-like theory that worked, there would be tons of astrophysicists who would be very excited to work on it. The problem is simply that none of the proposed MOND theories match the wide range of observations that LCDM does. LCDM is a simple theory that works remarkably well, much to the chagrin of the astrophysics community. It would be really exciting to find a problem in LCDM, and a lot of astrophysicists spend their time searching for such problems. See, for example, the excitement generated by the possible Hubble constant tension.

DiogenesKynikos 4y ago

> see Dwarf galaxy problem, for one example I assume you're referring to the "missing satellites problem." This problem is already essentially solved: 1. Newer, more sensitive surveys have detected more Milky Way satellite galaxies. 2. Reionization and supernova feedback quench star formation in small dark matter halos, meaning that the smallest dark matter halos never form galaxies. > See the review I linked. I think we've talked about this elsewhere on HN before, and I pointed out that the paper you're linking to gets a lot of things wrong and is published in an obscure journal (presumably because it wouldn't survive peer review at any of the major journals).

naasking 4y ago
> This problem is already essentially solved: "Essentially solved" is at best a euphemism for "we speculate that this will solve it". Hardly conclusive. > I think we've talked about this elsewhere on HN before, and I pointed out that the paper you're linking to gets a lot of things wrong and is published in an obscure journal (presumably because it wouldn't survive peer review at any of the major journals). A random HN comment claiming that a paper "gets a lot of things wrong" is not more convincing than the published paper itself. If you have an actual published paper or other review that addresses those points, then please point that out. Speculating as to why they published in an "obscure journal" can be explained by poor quality of the work, but it can also be explained by rampant disinterest in challenging orthodoxy, which also has a documented history of happening. Edit: to be clear, I'm not agreeing with the authors that MOND should be favoured given the evidence, but I disagree with your apparent position that MOND should be disfavoured and that LCDM is largely unproblematic.
- DiogenesKynikos 4y ago
  > "Essentially solved" is at best a euphemism for "we speculate that this will solve it". Hardly conclusive. No, it means that it's actually been solved. If you compare the theoretically predicted number of satellite galaxies to the observed number, there's no discrepancy any more. There was a discrepancy a decade ago. There isn't any more, both because of better observations (which detect more faint galaxies) and because of better understanding of the consequences of LCDM (in particular, how reionization and supernova feedback affect star formation in low-mass galaxies). > rampant disinterest in challenging orthodoxy That's just not the case. There's huge interest in challenging orthodoxy. If there were a MOND-like theory that worked, there would be tons of astrophysicists who would be very excited to work on it. The problem is simply that none of the proposed MOND theories match the wide range of observations that LCDM does. LCDM is a simple theory that works remarkably well, much to the chagrin of the astrophysics community. It would be really exciting to find a problem in LCDM, and a lot of astrophysicists spend their time searching for such problems. See, for example, the excitement generated by the possible Hubble constant tension.