A new paper looks for tidal distortions around two galaxies that apparently lack dark matter, and finds... something. It's not terribly dramatic, but it's enough to say that they probably are distorted. If so, then that pretty much rules out them having any dark matter, as if that were the case then they'd have to be a lot closer to the nearest major galaxy to suffer such an effect. This is neat, because it's a pretty strong constraint that these objects really are weird - and not just at smaller distances, as other authors have argued. As to how they formed though, that requires more data.

#Science
#Astronomy
#Galaxies
#DarkMatter

https://llittlephysicists.blogspot.com/2021/10/tantalisingly-tidal.html

I finally managed to read a paper. This one concerns a potential way to distinguish the predictions of Modified Newtonian Dynamics (MOND) from standard models of gravitation using dark matter. But while I know the authors are broadly pro-MOND, and their results look to me to favour MOND, that actually claim the opposite ! And then they go on to come up with elaborate ways to save MOND by making it even more complicated than it already is, which looks unnecessary to me even though I'm broadly anti-MOND... it's very confusing.

In brief, they look at how the rotation curves of galaxies vary within clusters. In the standard model, the environment of a galaxy shouldn't much affect its rotation speed. In MOND, a feature called the External Field Effect should mean you get declining rotation curves (lower velocities at greater distances from the galactic centres) in dense environments. That seems to be what the authors find, but for reasons I don't understand, they claim the opposite. Ho hum.

#Astronomy
#Science
#DarkMatter
#Galaxies

https://llittlephysicists.blogspot.com/2021/09/his-dark-accelerations.html

#outerspace #darkmatter

As a child I went to sleep trying to imagine the end of space. But there was no end to it. end. On and on it went.
Scientists state Outer Space is always expanding. But doesn't it need space to expand into? What a mind blowing mystery.

I think of a long ago forgotten tale. To get rid of a hole in a garment, you cut it out, but by doing so, you create a new and larger hole.To get rid of that new and larger hole, you cut it out…and on and on it goes. I don’t remember where that came from, only the astonishing,
impossible logic of it.

CERN Highlights 2020

Everything from antimatter to dark matter: new technology, new infrastructure, response to the Covid-19 crisis, science education, medical applications of accelerator technologies, art, ... our new tape library even gets a few seconds of glory at 4m59s.

#cern #2020 #darkmatter #antimatter #science #physics #technology #education #art #environment #medicine #covid #covid19 #rembrandt #data #tape #storage

KiDS these days! They would do anything to prove us wrong.

#KiDS #cosmology #Λ-CDM #CDM #DarkMatter #MOND

KiDS

However, the new KiDS results show a discrepancy: the universe is nearly 10 percent more homogeneous than the standard model predicts.

Dr. Marika Asgari, from the University of Edinburgh, who co-led the analysis, calls the result "intriguing". "The standard model of Cosmology relies on rather mysterious physics that we call dark matter and dark energy. Scientists have to test this remarkable model in as many ways as possible, and that is exactly what we are doing."

The KiDS results may indicate small cracks in the standard model, just like another discrepancy in the expansion rate of the Universe, the so-called Hubble constant. Dr. Tilman Tröster (University of Edinburgh): "The question is whether these can be solved with a small adjustment, for example with a somewhat more complex behavior of dark matter than the simple hypothesis of totally inert 'cold dark matter'."

Leiden professor and KiDS lead Koen Kuijken cannot say whether this will eventually lead to a fundamentally different theory, for example replacing Einstein's General Theory of Relativity with a new one. "For now, I consciously try to stay away from possible theoretical interpretations, and focus on the measurements and how to make them as accurate as possible."

http://kids.strw.leidenuniv.nl/pr_jul2020.php