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from the Now-you-see-it-now-you-don't-because-it's-dark? dept.
A galaxy has been found containing no dark matter, but that proves dark matter is real?
A distant galaxy that appears completely devoid of dark matter has baffled astronomers and deepened the mystery of the universe's most elusive substance.
[...] In the Milky Way there is about 30 times more dark matter than normal matter. The latest observations focused on an ultra-diffuse galaxy – ghostly galaxies that are large but have hardly any stars – called NGC 1052-DF2.
The team tracked the motions of 10 bright star clusters and found that they were travelling way below the velocities expected. "They basically look like they're standing still," said van Dokkum.
The velocities gave an upper estimate for the galactic mass of 400 times lower than expected. "If there is any dark matter at all, it's very little," van Dokkum explained. "The stars in the galaxy can account for all of the mass, and there doesn't seem to be any room for dark matter."
Paradoxically, the authors said the discovery of a galaxy without dark matter counts as evidence that it probably does exist. A competing explanation for the fast-orbiting stars is that the way gravity drops off with distance has been misunderstood – but if this were the case, all galaxies should follow the same pattern.
https://www.theguardian.com/science/2018/mar/28/galaxy-without-any-dark-matter-baffles-astronomers. The findings are published in the journal Nature.
(Score: 2) by bob_super on Friday March 30 2018, @10:50PM (5 children)
A bit like keeping on looking for Earth-like life around, it's hard to find surprising that puny humans for assuming that our physics apply to the rest of the universe.
My question, which has never been answered: We're good a physics now, but can anyone prove that our constants do not vary with the millions to billions of years between us and the galaxies we observe ? As the universe expands and changes, is it more rational to think that the laws are invariant, than the opposite?
I'm not an originalist, obviously.
(Score: 3, Insightful) by wonkey_monkey on Friday March 30 2018, @11:06PM
They all seem to be much like our own. We don't see any differences between galaxies 1 billion l.y. away or 10 billion l.y. away that would indicate any changes to the laws of physics over space or time. And if there were changes over space, you'd expect things to be different in different directions, which they aren't.
systemd is Roko's Basilisk
(Score: 1) by khallow on Saturday March 31 2018, @03:54AM (3 children)
No, that's very different. The problem here is that we can see the rest of the universe and thus, the physics of the rest of the universe, but we can't yet see planets with different sorts of life on them.
Because we looked.
(Score: 2) by HiThere on Saturday March 31 2018, @06:10AM (1 child)
That said, only some of the constants can be checked at a distance. But it would take a really weird theory to explain why only the ones we can't check would vary.
Javascript is what you use to allow unknown third parties to run software you have no idea about on your computer.
(Score: 0) by Anonymous Coward on Saturday March 31 2018, @01:48PM
There is a Heisenberg joke in there. Hidden.
(Score: 2) by PiMuNu on Saturday March 31 2018, @07:30AM
I thought there were reasonable "variable speed of light" theories around that conflict with inflation.
https://en.wikipedia.org/wiki/Variable_speed_of_light [wikipedia.org]