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> so it now seems more likely that our model of the universe is wrong. Anyone with an ounce of sense should have concluded that LCDM was wrong long ago. Hopefu

> so it now seems more likely that our model of the universe is wrong. Anyone with an ounce of sense should have concluded that LCDM was wrong long ago. Hopefully this will finally cause physicists to actually try something different.

mr_mitm 2y ago
You're not a cosmologist, are you? I'm not anymore either, but when I was in grad school, everyone agreed that LCDM is probably wrong. Most researchers pretty much wanted it to be wrong. All they did was try something different (quintessence, bigravity, modified gravity, f(R) theories, Horndeski gravity, phantom dark energy, chameleon cosmologies, coupled dark matter, etc. etc), but nothing fit the data as well as LCDM. When new data came in, and it pointed yet again at LCDM, it was considered a disappointment. Now the Euclid satellite has been launched, which I remember being the big hope that it will give us data that will finally enable us to tell which LCDM alternative could replace LCDM as the standard model of cosmology. You won't even get funding for such a mission unless you make a case for how it can improve our understanding of the universe. "We hope it will confirm our currently accepted view" will not get you one cent. So I'm not sure where you get the confidence that nothing different is being tried and that professional scientists wouldn't have an ounce of sense. I find it a bit disrespectful actually. I invite you to read the introduction (and introduction of part 1) of this review paper of the science behind the Euclid mission: https://arxiv.org/abs/1606.00180 https://arxiv.org/abs/1606.00180 It's understandable to laymen, co-authored by reputable, leading scientists in the field (disclaimer: I'm on the author list) and I hope that after reading it you would revise your opinion. Here is a short excerpt: > The simplest explanation, Einstein’s famous cosmological constant, is still currently acceptable from the observational point of view, but is not the only one, nor necessarily the most satisfying, as we will argue.
- naasking 2y ago
  > but nothing fit the data as well as LCDM. I think you mean, "nothing could be made to fit the data as well as LCDM". See below. > When new data came in, and it pointed yet again at LCDM, it was considered a disappointment. This is highly revisionist, and exemplifies the kind of cherry picking that has kept LCDM alive when it has outright failed numerous predictions and had to be adjusted after the fact to fit the data: From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity, https://www.mdpi.com/2073-8994/14/7/1331 https://www.mdpi.com/2073-8994/14/7/1331 LCDM is a complete mixed bag when it comes to predictions, where MOND has a very slight edge. It's absolutely clear that MOND is not correct or complete either, but it is undeniable that it has had greater predictive success than anyone anticipated and with far fewer free parameters than LCDM, mostly in areas where LCDM is weak. If LCDM can't explain why MOND has been so successful, which it currently cannot, then it is incomplete at best. Basically, the only good, almost definitive, evidence for particle dark matter is gravitational lensing, but if we're considering modified gravity anyway, then lensing isn't necessarily telling us what we think. On the flip side, no possible cold dark matter halo is compatible with recent observations that rotation curves are flat past a million light years [1]. I can't wait to see what epicycles they add to LCDM to save it this time. [1] https://tritonstation.com/2024/06/18/rotation-curves-still-flat-after-a-million-light-years/ https://tritonstation.com/2024/06/18/rotation-curves-still-f...
- naasking 2y ago
  A minor addendum: > So I'm not sure where you get the confidence that nothing different is being tried and that professional scientists wouldn't have an ounce of sense. I find it a bit disrespectful actually. Try talking to a MOND proponent and you'll get a very different picture of how open scientists are to alternate approaches and questioning LCDM.

mr_mitm 2y ago

You're not a cosmologist, are you? I'm not anymore either, but when I was in grad school, everyone agreed that LCDM is probably wrong. Most researchers pretty much wanted it to be wrong. All they did was try something different (quintessence, bigravity, modified gravity, f(R) theories, Horndeski gravity, phantom dark energy, chameleon cosmologies, coupled dark matter, etc. etc), but nothing fit the data as well as LCDM. When new data came in, and it pointed yet again at LCDM, it was considered a disappointment. Now the Euclid satellite has been launched, which I remember being the big hope that it will give us data that will finally enable us to tell which LCDM alternative could replace LCDM as the standard model of cosmology. You won't even get funding for such a mission unless you make a case for how it can improve our understanding of the universe. "We hope it will confirm our currently accepted view" will not get you one cent. So I'm not sure where you get the confidence that nothing different is being tried and that professional scientists wouldn't have an ounce of sense. I find it a bit disrespectful actually. I invite you to read the introduction (and introduction of part 1) of this review paper of the science behind the Euclid mission: https://arxiv.org/abs/1606.00180 https://arxiv.org/abs/1606.00180 It's understandable to laymen, co-authored by reputable, leading scientists in the field (disclaimer: I'm on the author list) and I hope that after reading it you would revise your opinion. Here is a short excerpt: > The simplest explanation, Einstein’s famous cosmological constant, is still currently acceptable from the observational point of view, but is not the only one, nor necessarily the most satisfying, as we will argue.

naasking 2y ago
> but nothing fit the data as well as LCDM. I think you mean, "nothing could be made to fit the data as well as LCDM". See below. > When new data came in, and it pointed yet again at LCDM, it was considered a disappointment. This is highly revisionist, and exemplifies the kind of cherry picking that has kept LCDM alive when it has outright failed numerous predictions and had to be adjusted after the fact to fit the data: From Galactic Bars to the Hubble Tension: Weighing Up the Astrophysical Evidence for Milgromian Gravity, https://www.mdpi.com/2073-8994/14/7/1331 https://www.mdpi.com/2073-8994/14/7/1331 LCDM is a complete mixed bag when it comes to predictions, where MOND has a very slight edge. It's absolutely clear that MOND is not correct or complete either, but it is undeniable that it has had greater predictive success than anyone anticipated and with far fewer free parameters than LCDM, mostly in areas where LCDM is weak. If LCDM can't explain why MOND has been so successful, which it currently cannot, then it is incomplete at best. Basically, the only good, almost definitive, evidence for particle dark matter is gravitational lensing, but if we're considering modified gravity anyway, then lensing isn't necessarily telling us what we think. On the flip side, no possible cold dark matter halo is compatible with recent observations that rotation curves are flat past a million light years [1]. I can't wait to see what epicycles they add to LCDM to save it this time. [1] https://tritonstation.com/2024/06/18/rotation-curves-still-flat-after-a-million-light-years/ https://tritonstation.com/2024/06/18/rotation-curves-still-f...
naasking 2y ago
A minor addendum: > So I'm not sure where you get the confidence that nothing different is being tried and that professional scientists wouldn't have an ounce of sense. I find it a bit disrespectful actually. Try talking to a MOND proponent and you'll get a very different picture of how open scientists are to alternate approaches and questioning LCDM.