Slashdot Mirror
Hubble Space Telescope Detects Ring of Dark Matter
mknewman wrote with a link to a story on the NASA site indicating that they may have finally found dark matter using the Hubble telescope. We've discussed the stuff a few times in the last year, with the Hubble actually mapping out the dark matter in the universe in January. This, though, may be our first 'sighting' of the elusive substance. "NASA will hold a media teleconference at 1 p.m. EDT on May 15 to discuss the strongest evidence to date that dark matter exists. This evidence was found in a ghostly ring of dark matter in the cluster CL0024+17, discovered using NASA's Hubble Space Telescope. The ring is the first detection of dark matter with a unique structure different from the distribution of both the galaxies and the hot gas in the cluster. The discovery will be featured in the June 20 issue of the Astrophysical Journal."
I heard it circles Uranus.
except, of course, all the astrophysicists who often pointed out that exactly this kind of discovery was just around the corner.
How we know is more important than what we know.
Screenshot or it didn't happen!
Redmond Washington.
Ok, mod me as troll. I deserve it.
---- Teach Peace. It's Cheaper Than War.
Is it just me, or are humans getting better and better at science as time progresses?
I mean, it seems likely that this would be the case, naturally. Nonetheless, it still strikes me.
We predict dark matter exists, then we show it exists. It seems pretty much assured that we will even find out what it is made of. This discovery further cements this feeling in my mind.
We figure there is a chemical of inheritance, we find DNA. We know there is a genome, we sequence it.
Everything seems to be a big puzzle, and we seem to be getting faster and more accurate with putting these puzzles together.
I feel fully confident in speculating, for instance, that we will solve the gene therapy issues in mere years. That we will have household humanoid robots by 2020 for under $50,000US. That we will enhance ourselves dramatically genetically and technologically by the end of the century.
Has science always been this inexorable in it's progress?
Read my Very Short "Stories"
I was about to write a comment panning this submission, because apparantly a one-paragraph press release - that doesn't give much room for an intelligent discussion - was the only information on this discovery. But I did find an abstract for a talk given at the American Astronomical Society Meeting 209, which was held in January this year.
Unfortunately I can't find the paper itself. So there is slightly more info, but not much :-(
It could happen. But if we piss off those robots and the genetically engineered humans, they may band together and start an extermination program of us humans. Then we'd have to flee the planet in a fleet of ships while the robots pursue us. Of course, with the genetically engineered humans, they'll look like us and they'd be used as spies. Of course, there may be a comuter scientist who falls in love with one of them and helps the robots take us out. Then he'll go insane and start imagining his robot lover.
I don't know if we really want to go there.
I prefer Flambe as apposed flamebait.
Given that the press conference isn't until May 15, I can't say for sure, but based on the brief blurb on the NASA website, it's almost certainly a gravitational lensing measurement.
It's true that dark matter doesn't interact directly with light, but it does curve space (ie. generate gravity), which light travels through. So light feels the gravitational effect of dark matter, a phenomenon known as "gravitational lensing". Essentially, the images of background galaxies going through a concentration of dark matter become magnified and distorted.
I don't know whether this is a strong lensing or weak lensing measurement. In strong lensing, the distortion is extreme and the images of the background get stretched into long tangential (and radial, though they're rarer) arcs like this. In the case of weak lensing, the distortion in any one image is small, but all images in a certain area are distorted coherently so you can statistically disentangle the signal.
Given the distorted images of the background galaxies, you can determine what mass distribution was responsible for those distortions, thereby producing a "mass map". It appears that in this case (again, based on the brief blurb), the mass map shows some sort of ring-like structure that isn't seen at any other wavelength (which non-dark matter would produce).
[TMB]
Why does the title read "Hubble Space Telescope Detects Ring of Dark Matter" when - as the first line of the summary states -, the HST actually only " may have finally found dark matter".
"Has found" and "may have found" are very different things. I "may have" the lotto ticket which is going to win me millions of dollars in Saturday's draw; on the other hand, I may not. To pre-emptively state a conclusion before it has been made is foolish and extremely unscientific and simply not an accurate description.
I challenge you to find much more information on Dark Matter... that isn't purely speculative. Whining about the lack of information is even worse than the wildest of speculations. Get in the game!
So far, it's all in the name; we can't really see it, ergo; dark. It has some sort of mass-effect in the universe, ergo; it matters. The only thing we can't agree on is what Dark Matter is. Let the speculations begin!
1. - Maybe it's a Quantum Substance and we've already determined it's nature by giving it a name. If it ever gets in the way, just shine a light on it and it disappears!
2. - What if it follows an Uncertainty Principle instead? Find a cloud of it, then put the lens-cap on the telescope. If I don't believe it's there when I take the lens-cap off, will it be gone? (Call it “Schroedinger's Haze”?)
3. - The residue of “unnecessary emotions” cast-off by an advanced species?
4. - Star farts?
I'd like to hear any better ideas... [ducks]
This post © Copyrite Duggeek, all rights reversed.
Not all scientific predictions are made equal.
The Raven
...last year: astronomers could see in the aftermath of two colliding galactic clusters.
The visible matter's momentum through space was impeded at quite a different rate than dark matter. This left four distinct zones of gravitational lensing, but only TWO were associated with visible matter. The other two were dark matter halos that had been separated from each galactic cluster.
There's a string of overhyped submissions here in the science section founded on a misreading of the source article.
Contrary to what the submission seems imply, the Hubble did not directly detect dark matter, and you can pretty safely bet that it won't ever.
What it did was find further evidence that dark matter exists. I don't think these media teleconferences are very rare, but they don't hold them every time somebody publishes a paper, either.
My reading of the press conference announcement is that the shape and motion of the galactic cluster in question is not possible based soley on visible mass. Furthermore, I suspect they will contend that assymmetry in their observations rules out with some degree of certainty an explanation of the observations using Modified Newtonian Dynamics (MOND), because such a finding would lead to the suspiscion that the dark matter is distributed differently from the galaxies and hot dust in the cluster (mentioned in the release). Currently MOND is the leading alternative theory to dark matter for explaining the galactic rotation curves, but it generally implies the dark matter effect should be distributed in the same fashion as normal matter.
It is the nature of the scientific method that contradicting one theory is further support for any unaffected competing theories. I think that's what is happening here. I don't think the legs are being kicked completely out from under MOND, but I'd bet it will be walking a little wobbly after this.
Leave Google out of this.
I had been under the impression that 'dark' matter was simply regular matter that we needed to exist to balance some equations, but that we couldn't see. Wouldn't this simply reduce the amount of dark matter by making it observable?
Or is my impression that dark matter is stuff we can't see wrong? Is it actually supposed to be some exotic substance (with comic-book like powers)?
More Caffeine. NOW
... there's damned little you can do with Hubble (other than observe in the ultraviolet, and honestly, when was the last time you heard about that capability leading to some huge discovery?) that you can't do with a reasonably large terrestrial scope.
Hubble is, by today's terrestrial standards, small. Its resolving power is limited, even in the relative vacuum of space, by the size of its mirror, the size, age and design of its instruments, and so on.
Yes, Hubble finds stuff. But it doesn't find disproportionately more stuff than 8-10 meter terrestrial scopes like Gemini, Subaru, or Keck.
Do the astrophysicists want it? Hell yeah - sure, big scopes on the ground can deliver results as good as Hubble's, but there aren't a lot of those to go around, and there's a limited amount of darkness, good weather, etc. So having Hubble in the mix means more research can get done, simply because there's another good tool available.
Just a thought.
Village idiot in some extremely smart villages.
Hmmmm....
The fact of the matter is, that doesn't look like dark matter to me, more like white matter.
Oh well, it doesn't matter...
Why, yes! I AM new here.
Err. No. We did *not* predict dark matter. We were not expecting dark matter or anything like it when the Zwicky first saw that there had to be some "more" matter in the galaxies to explain the observed rotational curves. He probably first said: "Gee, well, that looks funny!" Zwicky probably said something a lot better actually, as he was known for his, often rude, mannerisms.
The astonishing discoveries in science come when humans really have no clue what is coming next! Case in point: The November Revolution in Physics . That was the last time that the whole paradigm of understanding of particle physics shifted! That was back in 1974 and hasn't changed since! One new totally-unexpected particle, called the J/psi, was found and boom... the consequences were huge, for now, you *knew* that there had to more particles, namely the top and the bottom and that the W and the Z were predicted as well. Only after the discovery of all these predicted particles did the public came to accept the Standard Model and particle physics became a mature field. But, back in 1974, there were those who could see ahead in the light of this new discovery.
A large shift in the understanding of the universe happened already in astrophysics with the CMB(Cosmic Microwave Background) measurements. I liken it very much to the November Revolution. The CMB observations, first from COBE and later from WMAP and various other ground based observations, show with high statistics that there is something missing if we assume that the universe is all baryonic matter. Imagine a puzzle where there is a missing piece and now, you think of a piece that fits in this place. Well, dark matter fits the bill very well and other observations, also back it up. So somehow, dark matter is required by experimental results... Now, those who can see ahead make predictions on what we will --hopefully -- discover next: a dark matter candidate particle at the LHC, annihilation products of dark matter in space, a signal in gamma rays from annihilation, plenty of lensing examples in galaxies,.. This is called phenomenology for a reason. You get an idea inspired by experimental results from an experiment and look at what other phenomena you would observe in the light of your idea/theory.
End of my rant.
To put your "inexorableness" theory in perspective. There are more humans living on the planet right now, then has ever lived in total in the history of earth. So take humans and divide them into two groups: Group1: from the beginning of human evolution to 1920 and Group2: from 1920 to today. Group2 is significantly larger in population. Do you think Group2 achieved more? Really?!! I dont think so! I see most of the population watching TV and going to work where they try to minimize thinking! Group1 had to struggle more for survival and had to be more inventive to survive. The pressure is off on Group2. Laziness is settling in fast.
So where's your published paper where you provide an alternative theory to explain galatic rotation?