Slashdot Mirror
Half the Universe's Missing Matter Has Just Been Finally Found (newscientist.com)
An anonymous reader shares a report: The missing links between galaxies have finally been found. This is the first detection of the roughly half of the normal matter in our universe -- protons, neutrons and electrons -- unaccounted for by previous observations of stars, galaxies and other bright objects in space. You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull. But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so far. Two separate teams found the missing matter -- made of particles called baryons rather than dark matter -- linking galaxies together through filaments of hot, diffuse gas. "The missing baryon problem is solved," says Hideki Tanimura at the Institute of Space Astrophysics in Orsay, France, leader of one of the groups. The other team was led by Anna de Graaff at the University of Edinburgh, UK. Because the gas is so tenuous and not quite hot enough for X-ray telescopes to pick up, nobody had been able to see it before.
"Just been finally found"?
How about "Just been found" or "Finally been found"?
I've been saying for years that "dark matter" and "dark energy" aren't really things. They're placeholders for some type of matter or interaction we'll discover later.
That we're finally able to detect these baryon filaments is a solid step in the right direction to finally solving the "dark" mystery.
Not quite. TFA and TFS say that Dark Matter exists *and* they just found the missing "regular" matter. (highlighting mine):
You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull.
But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so far.
It must have been something you assimilated. . . .
They found some of the missing baryon matter. This is the normal matter that is around us every day. Dark matter is stuff that has momentum and exerts a gravitational field but doesn't interact electromagnetically, so we can't see it. We believe most of the matter in the universe is dark matter but we also believe there is a lot more of the normal baryon matter out there but we just don't know where or what it is. These studies have shown that there are filaments of hot gas stretching between galaxies. The density of this gas is extremely low but the volume it occupies is huge so it contributes to a large amount of the baryon matter in the universe.
Well let's hope they find it all at once. Because if they keep only finding half of what's missing we could be here forever.
Confucius say, "Find worm in apple - bad. Find half a worm - worse."
This has nothing whatsoever to do with dark matter or dark energy, and does nothing whatsoever to disprove the existence of either of those things. We knew this stuff existence, our models said it was in the intragalactic expanse, it's just it's hard to directly see because it's extragalactic: it's not inside stars, so it mostly doesn't emit light, and when it does it's not very bright.
In fact, I'd even go so far as to say that this is just more (indirect) evidence for the existence of dark matter: it helps confirm our models/simulations of galaxy formation, and those models don't work without dark matter, and considerable amounts of it (far more of it than the "missing" baryonic matter they found, in fact).
"None can love freedom heartily, but good men; the rest love not freedom, but license." --John Milton
This is the first detection of the roughly half of the normal matter in our universe -- protons, neutrons and electrons -- unaccounted for by previous observations of stars, galaxies and other bright objects in space. You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull. But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so far.
This paper is talking about the missing non-dark matter that the current models said should be there. I had nothing to do with dark matter, and the matter they found has no impact on the expected amount of dark matter in the universe.
I browse on +1 so AC's need not respond, I won't see it.
Baryon filaments have nothing whatsoever to do with dark matter or dark energy. Finding them is progress in validating current models since it finds matter that our current models say should be out there. It also strengthens the cause of "dark" matter/energy, since if our current models predict something (the presence of ordinary matter not currently detectable) that's verified by discoveries, it strengthens those models.
This still doesn't mean there has to be actual dark matter of course. Physicists once believed there had to be an "Ether" in which light waves could propogate, because it was the only reality they could model. When Michaelson and Morley showed that the speed of light was independent of direction of travel, physicists scrambled to attribute various properties to Ether to account for their findings. Einstein ended up modelling a reality where the speed of light was a universal constant, and his model was eventually proven to be more accurate than the etheric model.
It's very likely we'll never "see" dark matter. Likely we'll find a better model of the universe, something that makes gravity weaker at intergalactic distances, and dark matter will go the way of Ether. I'm less well versed in dark energy, but I bet it'll turn out to be something that vanishes too once we have a better universal model.
Completely agree with you - Occam's Razor Wins Again...
That's a butchering of Occam's Razor. The law is about preferring the most parsimonious hypothesis, i.e. the one that makes the fewest assumptions.
Dark matter being composed of a diffuse gas of standard baryonic matter could be the simplest hypothesis, but it makes many assumptions by implicitly refuting consolidating evidence against it. Wikipedia lists a few of them: https://en.wikipedia.org/wiki/...
You should really read the article. This isn't two independent groups scanning and suddenly discovering new pieces of the universe. It's basically a common data aggregating process applied to massive amounts of data to brighten faint emissions. Considering every star gazer with $5000 worth of equipment and a Mac does this every week, how many papers does that need to prove itself?
Of course the next step is to test it across more spots in the universe to hopefully find anomolies.
No.
It was behind the couch along with all the missing cat toys, single socks and car keys. ;)
Anons need not reply. Questions end with a question mark.
And I stand by my statement about three peer-reviewed papers.
Well if you read to the bottom of TFA, there are links to two papers. So just need one more to shut you up then?
I browse on +1 so AC's need not respond, I won't see it.
> we can observe it's gravitational interactions
Perhaps it's made of superfluous apostrophes?
Apologies, but almost all of this is wrong.
Models based on observations indicated that 4% of the universe's mas/energy composition had to be normal, baryonic matter. Half of that 4% was missing until today. Dark matter, based on observations, needs to be approximately 23% of the mass of the universe. Otherwise galaxies would not have formed and would spin apart. Further, most of the mass of dark matter is associated with galaxies, and this matter was found between them. Details "matter" (unless of course they "energy").
It's kind of like that 'asteroid belt' between Mars and Jupiter. When you see it in movies, they show it like the asteroid field in Star Wars (Empire Strikes Back, I think) where there are thousands of asteroids very close to one another and constantly smashing into one another. In reality, the average distance between objects is something like 2 million miles and most of them aren't any bigger than a basketball. All the asteroids put together wouldn't create a planet even half the size of Pluto.
Neurons and synapses. The universe is a brain.
The cool kids are spelling it "brane" now.
His ignorance covered the whole earth like a blanket, and there was hardly a hole in it anywhere. - Mark Twain
Nope, this "found" matter was already accounted for in the known matter area. The amount of dark matter / dark energy hasn't changed.
Sorry, I had it in reverse. They detected the gaps in the light left from the Big Bang. Basically shadows of the gas particles. The lukewarm gas itself doesn't emit anything detectable. Put together a bunch of pictures of microscopic gaps and you can build up a shadow of a mass in the shape of a thread.
Nope, this "found" matter was already accounted for in the known matter area. The amount of dark matter / dark energy hasn't changed.
I understand that claim, but TFS sure as shit didn't make that clear.
Regardless, the entire premise of "dark matter" is that our observations of matter are incomplete.
It's fundamentally a "knowns, known unknowns, unknown unknowns" shell game.
You're claiming that this was part of the "known unknowns" because we "know" the sum of the "knowns" and "known unknowns". This may be what TFA is saying, but the very fact that we have an "unknown unknowns" category means we really don't "know" shit. That category was literally made up to make the math work given our assumptions.
It's also not half the missing matter. Dark Matter is matter just not made of atomic constituents (protons, neturons and electrons) generally called baryonic matter. Only 4% of the universe is made of baryonic matter which, if the summary is correct and the half of this which was missing has been found this means that only 2% of the missing mass-energy of the universe has been discovered. There is a remaining 25% of the mass-energy of the universe in Dark Matter (which is still matter, just not baryonic) and ~71% which is Dark Energy which is the vacuum energy.
So, I suppose if you just refer to matter alone then ~ 7% of the missing matter of the universe has been found but that is still nowhere near 50%, to claim that much you have to specify "50% of baryonic matter" or find Dark Matter (but in that case it would probably be a lot more than 50% found).
You should check out the history of the discovery of the neutrino, a particle invented to make the maths work given our assumptions. Also very similar to dark matter as it barely interacts with normal matter.
Interestingly when Fermi refined the theory giving a neutrino, Nature refused to publish it as too far out there.
https://en.wikipedia.org/wiki/...
The positron also was theorized first on the basis that Dirac's new theory allowed it. Though at first it wasn't considered as a new particle. https://en.wikipedia.org/wiki/...
https://en.wikipedia.org/wiki/Inverted_totalitarianism
Dark matter comes from the dark side. It is pure evil in a can. On Earth, it is also pickled and then known as lutefisk.
Browsing at +1 - no ACs, I ignore their posts. So refreshing!
Apologies, but almost all of this is wrong.
Models based on observations indicated that 4% of the universe's mas/energy composition had to be normal, baryonic matter. Half of that 4% was missing until today. Dark matter, based on observations, needs to be approximately 23% of the mass of the universe. Otherwise galaxies would not have formed and would spin apart. Further, most of the mass of dark matter is associated with galaxies, and this matter was found between them. Details "matter" (unless of course they "energy").
Perhaps I'm mistaken, but according to current theories (e.g., the standard 6-parameter lambda-CDM model)...
~4% baryonic matter
~23% dark matter (needed to explain formation of galaxies and larger scale structures)
~73% dark energy (needed to explain observed expansion rate of the universe)
This current discovery only addresses part of the postulated, but previously unobserved 4% baryonic matter.
FWIW, Dark matter is a bit a kludge in that a single type of dark matter in the model (cold dark matter) doesn't seem to explain things either (this is called the small scale problem). So there are proposals for "warm/cold" dark matter. And nobody really has a clue about dark energy... So yes, details "matter".
You have probably heard about the hunt for dark matter, a mysterious substance thought to permeate the universe, the effects of which we can see through its gravitational pull. But our models of the universe also say there should be about twice as much ordinary matter out there, compared with what we have observed so far.
So yes, the article (and also the summary quoted) made it very clear that this discovery had nothing to do with Dark Matter and doesn't change any calculations regarding Dark Matter.
You have to think of it more like the stringy bits of cheese when you tear a slice off a pizza. Or the vomit running off your chin after 10 pints of lager, 5 large whiskies and an extra large four cheese pizza. It can help understanding to picture the universe as a mixture of alcohol, doughy cheese and stomach lining.
What the two teams detected now was matter which differs in at least two aspects from Dark Matter:
And the other half... is AOL discs... am I right?
The title says "matter" and whatever Dark Matter is it is most definitely matter so either the reference to "matter" is wrong or the 50% number is wrong because what is described is not the discovery of 50% of the missing matter in the universe, only 50% of the missing baryonic matter.
So what you are saying is that you didn't even bother to read the summary, much less the article or the actual papers linked in the article, and you are arguing the validity of all that based on the headline?
I browse on +1 so AC's need not respond, I won't see it.