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From New Atlas:
Some of the strongest evidence for dark matter to date has been discovered – and ironically, that's thanks to its absence. In a pair of studies published this week, astronomers have shed new light on dark matter through close observation of a galaxy previously found to have very little of the stuff, while the same team found a new example of a similar oddball galaxy.
It's generally believed that galaxies are held together through the gravitational influence of clumps of dark matter, so to find a galaxy with little to no dark matter was a surprise. And while it might sound like a strike against the theory, it actually ends up supporting it.
A Second Galaxy Missing Dark Matter in the NGC 1052 Group (DOI: 10.3847/2041-8213/ab0d92) (DX)
Still Missing Dark Matter: KCWI High-resolution Stellar Kinematics of NGC1052-DF2 (DOI: 10.3847/2041-8213/ab0e8c) (DX)
(Score: 1) by khallow on Tuesday April 02 2019, @10:35AM (11 children)
The data preceded the prediction (keep in mind that the theory had to be modified in the first place to explain the sort of system which is adjacent to a large mass, and hence, would be mostly likely to be stripped of dark matter in the dark matter theories). And you still neglect the big issue. MOND has all sorts of adaptations to fit observation. But we continue to find things it needs to adapt to. For a short list:
Seriously, why is the presence of dark matter considered a big problem even though we still have much we don't understand about such things, but the presence of aphysical characteristics not considered a problem? My view is that dark matter is simply stuff that we haven't seen yet - sorry, that's not that big a stretch despite all that has gone on, and MOND is a massive ad hoc with a number of justifications based only on explaining incomplete data.
(Score: 0) by Anonymous Coward on Tuesday April 02 2019, @10:56AM (3 children)
You seem incapable of even recognizing that in this very case someone published a MOND-based prediction, then later another group published rotation curve data that matched the prediction.
There is no room for ad hoc adjustments to MOND, it is set in stone since 1983. The only thing is getting good estimates of the parameters to plug in. So every time you repeat that it is false. You can go look at the original papers to see it (but I know you won't).
It is pointless to discuss something with someone who just repeats falsehoods that are easily disproved by just reading a few sentences in a journal article they refuse to look at. That is messed up dude.
(Score: 1) by khallow on Tuesday April 02 2019, @12:56PM (2 children)
Open cluster data predates 1983. And I don't buy that current MOND-based predictions are based on that theory.
(Score: 0) by Anonymous Coward on Tuesday April 02 2019, @01:12PM (1 child)
You just "don't buy it", because data mentioned in a paper existed before the paper was written. That is your argument now...
This is so sad, on other topics you seemed to have an actual thought process.
(Score: 1) by khallow on Tuesday April 02 2019, @01:51PM
Yes. That's correct. Please recall the key problem. There is no physical explanation for any part of MOND, then or now. It's instead an adjustment to existing theory to explain discrepancies. That's exactly the role of dark matter as well. Both are epicycles.
Further, we have the problem of the gravity environment. Somehow MOND claims that these disperse galaxies are close enough higher mass to have these mechanics, but not the galaxy, NGC 1052 which is generating the external gravitational field in question. NGC 1052, instead has a dark matter halo [hawaii.edu] (possibly with two axes, "Some galaxies (e.g.NGC 1052, M32)are well-fit by two-integral models"). Think about that. Something outside of a galaxy has no MOND effect allegedly due to the external gravitational field of the galaxy, but the galaxy itself does. How did the gravitational field grow that much stronger outside NGC 1052 that it eliminated the MOND effect?
(Score: 2) by Gaaark on Tuesday April 02 2019, @02:02PM (6 children)
"Seriously, why is the presence of dark matter considered a big problem even though we still have much we don't understand about such things,"
And yet you have big problem with QI, even though it is a better, more scientific model.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1) by khallow on Wednesday April 03 2019, @04:16AM (5 children)
The catch is that MOND at least explains most galaxies with "no" dark matter effects as being embedded in a stronger gravitational field. QI seems to predict that dark matter effects should be stronger because of the weak internal gravitational field of the galaxy rather than the opposite which is actually observed.
(Score: 2) by Gaaark on Wednesday April 03 2019, @10:21AM (4 children)
Uhhhh,...QI seems to predict there IS NO dark matter.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1) by khallow on Wednesday April 03 2019, @12:51PM (3 children)
(Score: 2) by Gaaark on Wednesday April 03 2019, @10:45PM (2 children)
Okay, I guess I don't understand where you are going.
QI only deals with motion and speed: galaxies don't fly apart due to inertia.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 1) by khallow on Wednesday April 03 2019, @11:12PM (1 child)
The problem here was motion and speed of rare sorts of galaxies that the other two theories have figured out how to shoehorn explanations for. The QI explanation is lacking since the galaxies in question are low density satellite galaxies, most of their mass got robbed by NGC 1052 in some long ago collisions. So they're precisely the sort of low local gravity objects that QI should be describing. Unless QI has the MOND issue where external gravitation fields (here from NGC 1052) cause the physics to somehow change.
(Score: 2) by Gaaark on Thursday April 04 2019, @01:37AM
run the numbers against his formula.
I'm betting you get the numbers you're looking for.
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---