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from the shedding-some-light-on-the-matter dept.
Dark Matter is Not Made Up of Tiny Black Holes:
An international team of researchers has put a theory speculated by the late Stephen Hawking to its most rigorous test to date, and their results have ruled out the possibility that primordial black holes smaller than a tenth of a millimeter make up most of dark matter. Details of their study have been published in this week's Nature Astronomy.
Scientists know that 85 per cent of the matter in the Universe is made up of dark matter. Its gravitational force prevents stars in our Milky Way from flying apart. However, attempts to detect such dark matter particles using underground experiments, or accelerator experiments including the world's largest accelerator, the Large Hadron Collider, have failed so far.
This has led scientists to consider Hawking's 1974 theory of the existence of primordial black holes, born shortly after the Big Bang, and his speculation that they could make up a large fraction of the elusive dark matter scientists are trying to discover today.
The scientists theorized that primodial black holes between Earth and the Andromeda galaxy. Were one to lie between us and a star, then it would cause the star to appear to brighten for a few minutes or hours.
From 190 images of the Andromeda galaxy taken over the course of a single, 7-hour observation, the researchers expected to see about 1000 events. They saw... just one. They haven't given up trying to locate the "missing mass" — mass we have not yet identified, but would be needed to explain the orbital properties of galaxies. To wit:
The researchers are now planning to further develop their analysis of the Andromeda galaxy. One new theory they will investigate is to find whether binary black holes discovered by gravitational wave detector LIGO are in fact primordial black holes.
Journal Reference:
Hiroko Niikura, et. al. Microlensing constraints on primordial black holes with Subaru/HSC Andromeda observations. Nature Astronomy, 2019; DOI: 10.1038/s41550-019-0723-1
(Score: 5, Insightful) by bradley13 on Wednesday April 03 2019, @11:58AM (21 children)
"Scientists know that 85 per cent of the matter in the Universe is made up of dark matter."
Um...no, they "know" no such thing. Scientists know that gravity doesn't appear to behave as they expect, when observing distant objects. Dark matter is a kludge. There are other kludgy theories, like having natural constants vary over time and space, or fudging the cosmological constant.
Personally, I think the FSM has stashed some extra pasta in another dimension, and we're detecting the resulting gravity. Squid-ink pasta - hence "dark matter".
The real explanation almost certain lies elsewhere. We just haven't figured it out yet.
Everyone is somebody else's weirdo.
(Score: 3, Funny) by The Mighty Buzzard on Wednesday April 03 2019, @12:05PM (16 children)
Missing socks. You know how every time you wash whites you end up with at least one unmatched sock? It's out in space confusing physicists along with all its unmatched friends.
My rights don't end where your fear begins.
(Score: 4, Funny) by c0lo on Wednesday April 03 2019, @12:34PM (15 children)
The easiest and most immediate solution to solve the problem of the white sock missing after wash, never lost one ever since I discovered it.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by The Mighty Buzzard on Wednesday April 03 2019, @12:49PM (10 children)
Das racis!
My rights don't end where your fear begins.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @02:44PM (4 children)
That's right! You're supposed to say, *I only wear colored socks*. It's more inclusive.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @04:17PM (1 child)
It should have been "dark socks"...
(Score: 3, Funny) by bob_super on Wednesday April 03 2019, @05:50PM
Talking about Dark Socks in the comment about a space article makes me think that Mel Brooks could make another Star Wars parody...
The problem would be getting sued by Disney, who are also doing that.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @07:56PM
My socks are African-American... uh... Mexican.
(Score: 2) by c0lo on Wednesday April 03 2019, @10:19PM
No, black socks reign supreme on my feet, you won't see any other colour.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 3, Funny) by c0lo on Wednesday April 03 2019, @11:01PM (4 children)
A younger and more inquiring mind would have liked to know "if a black sock develops a hole, what colour will that hole be?"
Looks like your mind is too full of answers to allow new questions (grin)
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by The Mighty Buzzard on Thursday April 04 2019, @12:26AM (3 children)
No, I just already had the answer to that one. Toe colored.
My rights don't end where your fear begins.
(Score: 2) by c0lo on Thursday April 04 2019, @01:29AM (2 children)
True while worn, still a mystery while in the washing machine (as still a mystery is the nature of the interaction with the rest of the load).
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by The Mighty Buzzard on Thursday April 04 2019, @12:26PM (1 child)
Schrödinger's sock then?
My rights don't end where your fear begins.
(Score: 2) by c0lo on Thursday April 04 2019, @12:41PM
It predates Schrödinger by at least some centuries, 't's a Hamletian sock
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by BK on Wednesday April 03 2019, @03:28PM (1 child)
Agreed. And they never get dirty!
...but you HAVE heard of me.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @10:15PM
Oh, but they do. When they do, they are sorta turning towards white.
(Score: 0) by Anonymous Coward on Thursday April 04 2019, @01:16AM (1 child)
So *YOU* are the source of this ominous dark matter thing!
(Score: 2) by c0lo on Thursday April 04 2019, @01:26AM
Inconclusive. The colour of the matter emitted by holes in black socks in not yet settled.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @02:21PM (1 child)
I think we need to kill more cats ..... that will give some answers to this problem /dark humor
(Score: 2) by Osamabobama on Wednesday April 03 2019, @07:24PM
What's the matter with dark humor?
Appended to the end of comments you post. Max: 120 chars.
(Score: 1, Interesting) by Anonymous Coward on Wednesday April 03 2019, @03:36PM (1 child)
Is dark matter an extra-dimensional effect? [arxiv.org]
- M. E. Kahil, T. Harko
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @04:21PM
Interesting.
(Score: 5, Interesting) by opinionated_science on Wednesday April 03 2019, @12:13PM (10 children)
There is a UK professors that has been working on an idea for a few years. He has developed a parameter free model that explains the data.
The theory is called Quantised Inertia [blogspot.com] and is a really interesting extension to the understanding of gravity.
There are some very easy to follow articles on the blog as well as peer-reviewed publications - highly recommended.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @12:25PM
Yes, this also explains why MOND works right?
(Score: 4, Insightful) by Immerman on Wednesday April 03 2019, @02:01PM (7 children)
Does it also explain the recent galaxy discovered whose motion is accurately described without invoking dark matter?
It's anomalies like that that are the proving ground for scientific models - if your model can't describe the anomalies using the same theoretical constructs and constants as it uses for the normal samples, then it's almost certainly wrong.
(Score: 1, Informative) by Anonymous Coward on Wednesday April 03 2019, @02:35PM (4 children)
Probably, it gives predictions very similar to MOND.
MOND's predictions are so far consistent with both (NGC 1052-DF2 and NGC 1052-DF4). See table 2 here:
https://arxiv.org/abs/1901.02679 [arxiv.org]
Compare to:
https://iopscience.iop.org/article/10.3847/2041-8213/ab0d92/meta [iop.org]
https://iopscience.iop.org/article/10.3847/2041-8213/ab0e8c [iop.org]
(Score: 1, Informative) by Anonymous Coward on Wednesday April 03 2019, @02:40PM (3 children)
Source:
http://physicsfromtheedge.blogspot.com/2018/06/visit-to-julich-supercomputing-centre.html [blogspot.com]
(Score: 2) by Immerman on Wednesday April 03 2019, @07:31PM (2 children)
It's the adjustable "constant" that makes MOND really hard for me to take seriously. If you need to adjust the "constant" to fit different galaxies, all you have is a general empirical description, not a physical model.
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @08:19PM
There is one universal constant for all galaxies, but no one knows what exactly it is. It is heavily constrained to be about 1.2*10^-10 though, so usually people just use that value.
The quantitative inertia guy says his models do not even have that one universal value to measure. Compare to GR plus dark matter which has nearly infinite tunable parameters (at least one for each galaxy).
(Score: 0) by Anonymous Coward on Wednesday April 03 2019, @08:38PM
For example, in the MOND prediction paper linked above you can see they used the same a0 = 1.2e-13 km/s^2 value for all the galaxies that has been used since 1983. Units for my sister post are missing but were m/s^2.
(Score: 2) by opinionated_science on Wednesday April 03 2019, @09:10PM (1 child)
He posts regular updates, as data becomes available. I think he's really overworked, like most researchers not engaged in mainstream research.
He's got a bit of funding to measure the effects in the real world (from DARPA!) , but like most, I want to see the evidence first.
In the same way Einstein augmented Newton, it's entirely plausible for further augmentation to our understanding of gravity.
(Score: 2) by Gaaark on Wednesday April 03 2019, @10:39PM
Read my posts all over the place, lol. I'm glad you've joined me in the good QI fight!
Thumbs up!
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 2) by Gaaark on Wednesday April 03 2019, @10:34PM
HEY! He's stealing Gaaarks thunder!
oh...wait. I'm Gaaark.
Welcome QI friend!
:)
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 0, Redundant) by Gaaark on Wednesday April 03 2019, @10:40PM
Not made of black holes because, say it with me, DARK MATTER DOESN'T EXIST!
--- Please remind me if I haven't been civil to you: I'm channeling MDC. ---Gaaark 2.0 ---
(Score: 0) by Anonymous Coward on Thursday April 04 2019, @01:33AM
The primordial black holes in this study are no smaller than 10^-11 solar masses, or about 10^19kg. This is about the mass of a small moon or large asteroid (less massive than Ceres). It's odd that these would be candidates because black holes this small would be very bright due to Hawking radiation and would radiate away their mass within the lifetime of the universe. That is, they probably don't exist at all. But black holes near the upper end of the mass range in the experiment would be stable.
The *other* kind of micro black hole dark matter candidate, the Planck-mass black hole (also called a Planck particle), isn't detectable by this kind of experiment. This is a black hole with mass equal to the Planck mass and radius of the Planck length.
(Score: 2) by Muad'Dave on Thursday April 04 2019, @01:32PM (1 child)
I watched a Science Channel show where the physicists pondered whether supermassive black holes are made of (or at least seeded by) dark matter [wikipedia.org]. Interestingly, they claim that there's no mechanism for black holes of that size to exist if made of normal matter.
(Score: 0) by Anonymous Coward on Thursday April 04 2019, @01:47PM
There is probably no dark matter and no black holes, so this is angels dancing on pins level stuff.
There may have been primordial black holes (https://en.wikipedia.org/wiki/Kugelblitz_(astrophysics)), but they have all evaporated or "solidified" by now.