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Hubble Builds 3D Dark Matter Map
astroengine writes "Dark matter can't be spotted directly because it doesn't interact with electromagnetic radiation (i.e. it doesn't emit any radiation and reflects no light). However, its gravitational influence on space-time can bend light from its otherwise straight path (a phenomenon known as 'lensing'). Using a sophisticated algorithm to scan a comprehensive Hubble Space Telescope survey of the cosmos, astronomers have plotted a map of 'weak lensing' events. Combining this with red shift measurements from ground-based observatories, they've produced a strikingly colorful 3D map of the structure of dark matter."
...but I fail to see the 3D that was promised by TFA.
I agree it's a nice picture but there seems to be no explanation as to what these colours actually mean, let alone any kind of conclusion drawn from what I presume to be "pockets of dark matter".
Anyone care to enlighten me?
The pic looks like the Zetarians.
Sig this!
looks photoshopped to me
If you mod me down, I will become more powerful than you can imagine....
...especially when you consider it's a picture of something that very possibly doesn't even exist.
There isn't any "scale bar" because you are not looking at something at any fixed distance! You are looking at (theoretically) blobs of stuff at various distances.
You could do it based on movement speeds. Things in the background of an image move slower than those in the midground when you change your position--If the thing in the background, a galaxy or something, moves in a strange way, then you can be sure it's being lensed. I'm not sure if the Earth moves enough for this to be useful, though, given the scale.
Conscience is the inner voice which warns us that someone may be looking.
looks like a My Little Pony pegasus got up there and jizzed all over the lens...
Lensing is known to happen with black holes and other massive bodies how does this map distinguish dark matter from other sources of lensing? By stating Dark matter has no interaction with electromagnetic radiation clearly contradicts the support that it also bends light. Unless "interaction" has a separate astrophysical meaning which is unfamiliar to me. I don't see how this gets us any closer to understanding the nature of dark matter/energy.
(To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.])
That might be something similar to what they told Einstein when he used his math to explain characteristics of nature that no one had witnessed.
I find the possibility of dark matter and energy kind of fascinating. Maybe it just a problem with their math - but then again, having huge amounts of mass in the universe be something other than what we experience every day adds a little mystery to it all.
Why are you letting these clowns ruin our country?
Sorta. As the earth goes around the sun, we do in fact get enough parallax to determine the distance to nearby stars. On the galactic scale, though, this doesn't work. The way they find lensing artifacts is that lensing doesn't just skew a single flat image of what we see, it might bend the same light source so it comes at us from different angles, producing multiple images of a single event. Something like this: http://en.wikipedia.org/wiki/Einstein_Cross
If they have good enough images with spectral plots for each pixel (which if they are using redshift to determine distance, they must have), I could see an algorithm being able to pick out which images are mirages, and therefore where the lensing matter must be.
... the disturbance I felt in the Force earlier. I thought I just had gas.
It's not arrogance; frankly, a true scientist is thrilled at the prospect of being proved wrong. It means they're answering some long-standing questions and posing countless new ones. Furthermore, the concepts of "dark matter" and "dark energy" are still only theories; scientists have yet to definitively prove the existence of these entities. These theories just happen to be the best explanations for what scientists observe.
The bottom line remains what osgeek above me said: it's easy for you to call the scientists who postulate dark matter "arrogant" considering it's something that has about as much impact on our daily lives as Einstein's Theory of Relativity does (which, when it was being proved, required very specific measurements to be taken, measurements that could only be gathered in a solar eclipse...how's that for completely unnecessary to quotidian life?).
No, right now we can't definitively prove that the 3D image referenced in TFA is indeed dark matter. But within the parameters of the current hypothesized model, that is what scientists believe to be pockets of dark matter.
"I'd just like to emphasise that taking a million years isn't a metaphor here..." -Rich Bradshaw
...how they know it’s lensing, and that the stars aren’t just positioned like that?
Sounds to me like you could never prove, which one it really is, until you fly behind that “dark matter”. (To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.])
When you see multiple images of the same object, it's lensing. This is, in fact, how gravitational lensing was first discovered. Check out this great wikipedia image of the effect: http://en.wikipedia.org/wiki/File:Einstein_cross.jpg. This is actually called strong lensing. TFA discusses weak lensing, which is a much smaller effect. That's detected by looking at very distant galaxies. Lensing changes the shape of galaxies such that there is a preferred orientation. If this orientation is statistically significant, i.e., too many galaxies are stretched in the same direction to be caused by normal physics, then it tells us that the weirdness is likely caused by lensing. Thanks to Hubble's ability to paint an incredibly dense picture of background galaxies, our statistics are based on a huge number of samples and we can trust them pretty thoroughly.
Awesome, right?
"I zero-index my hamsters" - Willtor (147206)
There's a good explanation by Patricia Burchat in a TED talk: http://www.ted.com/index.php/talks/patricia_burchat_leads_a_search_for_dark_energy.html
If impatient, jump to 4:20 for how do they use lensing.
So luminiferous and aethereal! Almost magical like!
Or is my pattern-recognition generating a false positive?
I'll go farther than that: I can remember how before the Hubble was launched, scientists didn't think we'd ever actually be able to observe the effect because it was too small to be imaged from any ground-based telescope.
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Mod parent up. Also, gravitational lensing sometimes produces distinctive distortions and arcs.
...how they know it’s lensing, and that the stars aren’t just positioned like that?
I think it's because, in a perfectly flat space-time, only light that starts out coming directly at us will reach us. However, in our universe, heavy stuff can make light reach us that did not originally start coming at us. Also, when this bent light hits us, it appears to be coming from a direction that is not its true starting point.
Now, here's the key: Two photons starting at a star going in slightly different directions can both reach us, due to the heavy stuff out there bending space-time. When they reach us, they appear to be coming from slightly different directions. If we can tell that both photons came from the same star, then we can calculate what heavy stuff made that gravitational lensing effect.
Also, pretty pictures: Gravitational lens - Wikipedia, the free encyclopedia
There was this recent article on a popular news site for geeks - ah, here it is: 90% of Universe Found Hiding in Plain View.
Just the other day there was an article about finding the remaining 90% of the universe that was previously missing by simply looking at the frequency spectra associated to hydrogen. Showing a whole lot of more galaxies than what previously was seen.
...how they know it's lensing, and that the stars aren't just positioned like that?
Much like with regular lenses, there's more to it than just a change in apparent position.
To me still a imaginary excuse, based on the arrogance of not being able to admit that the math is wrong, but instead calling the universe wrong! ^^ [But a good {and compact!} explanation will of course change my mind.]
Once we discovered extra-galactic dark matter, it became really hard to find a different explanation. Coming up with a way to modify gravity to not need dark matter (but still explain everything "the math" explains perfectly) was hard enough. Once you had to modify gravity to not even point at the known center of mass, it kinda becomes unworkable.
And people were trying to eliminate the need for dark matter! In contrast to this somewhat weird sounding definition of "arrogance", there are physicists around the globe who are arrogant enough to think that they're smarter than whoever came up with "the math", and they could be the ones to prove the theory wrong and present a new one. One that would be named after them.
Or Newton again, in the case of MOND. It's still name-in-history(well, physics) books type stuff.
Anyway, although gravitational lensing has plenty of evidence already, this data actually confirms another aspect of the predicted lensing effect and its relation to redshift, provides yet more evidence for dark matter, and even corroborates universal expansions. Multiple theories and predictions working in concert and completely consistent with observation. That's what you call a slam dunk. The game isn't over, but there's a reason this is the favored math at this point in time: it works.
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Actually, it does exist. Frankly, I'm fucking sick of posting the same links over and over, so why don't you just go to Wikipedia and read about the Bullet Cluster. There is simply no question, now, even among MOND proponents: there is weakly interacting matter out there, and we have no idea what it is.
I actually submitted a story on this exact same topic back in 2007. The only thing new they seem to have now is a nicer picture, the article seems much lighter than the original article I linked to three years ago. The new article doesn't seem to indicate any new science that has developed since then, not even links or mentions of any new publications updating the findings in 2007, or even mentions of the scientists who are behind this work...
Qu'on me donne six lignes écrites de la main du plus honnête homme, j'y trouverai de quoi le faire pendre.
http://www.spacetelescope.org/goodies/printlayouts/html/heic1005.html
These posts express my own personal views, not those of my employer
And a little more about how they did it:
http://www.spacetelescope.org/images/html/heic1005c.html
These posts express my own personal views, not those of my employer
You are mistaken. Parallax only works for nearby objects (basically the nearest stars).
Here's how it was done:
http://www.spacetelescope.org/news/html/heic1005.html
Also look at each of the descriptions on the image links on the right hand side.
These posts express my own personal views, not those of my employer
I agree to a point. Its either a fist or a chicken, a duck and swan and a dolphin are flying in front of the camera.
Space is so far out man!
It's the aether, of course. =^)
--
Toro
This is one of the lamest things I have ever seen. OMG is this a joke or what!? If these guys are serious someone needs to pull the plug on these assholes before someone gets hurt. Check out thunderolts.info or read "The Big Bang Never Happened" But for gods' sake don't eat this shit sandwich!
"These theories just happen to be the best explanations for what scientists observe."
Exactly! Dark matter and dark energy are just tags for unexplained phenomena that appear to have similar properties to matter and energy. They are not simply mathematical entities, they are phenomena that can be observed but cannot (yet) be explained with our mathematical models. This is no different to any other physics, Newton didn't discover gravity he discovered it could be described with maths.
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Is it me, or did that pic give anyone else a TOS flashback where they meet some energy-based alien that fucks with the ship?
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how are we sure it's gravity producing the lensing effect and not some other force?
If you mod me down, I will become more powerful than you can imagine....
"Within a few decades it will be proven that neither dark matter nor dark energy exists; they're just hypotheses to fill the gaps between the observed behavior of the universe and our current understanding of the laws of physics."
Dark energy/matter are the names of the observed phenomena just as energy/matter are names for similar phenomena. If they are (as you claim) the names of specific hypotheses then what are the phenomena called?
And did you exchange a walk on part in the war for a lead role in a cage? - Pink Floyd.
Yes. That's called parallax. Is measurable only in stars which are close by.
* good out to 100 pc
* only get 10% distances out to a few parsecs.
* only a few hundred stars are this close
http://www.astronomy.ohio-state.edu/~pogge/Ast162/Unit1/distances.html
how are we sure it's gravity producing the lensing effect and not some other force?
Because gravity is the only force we know that is capable of doing so.
Don't tell me to get a life. I had one once. It sucked.
...is totally normal matter, but invisible for us because it is located in another universe? I am not a physicist so my idea might be totally wacko, but ages ago I watched the BBC documentation 'The elegant universe'. One of the string theories explained there proposed that the reason gravity is so weak compared to other major forces is that the 'strings', which are responsible for gravity have the ability to migrate into parallel universes. Therefore we always feel only a fraction of the gravity mass 'produces'. <--- Please be lenient with my very unscientific wording. :-)
So when I saw this documentation I always wondered, when 'our' gravity migrates into other universes, shouldn't also migrate gravity from other universes into ours? I wondered if this theory was true, how would a black hole in a parallel universe look like here?
So maybe, if we had the ability to fly to those places where hubble located the 'dark matter', we would find nothing. The space is curved there for no apparent reason. It is actually because of normal matter in a parallel universe.
Nice quote from independance day.
(do remember though that said movie is classified as "fiction")
Well, if the language doesn't want to be raped it shouldn't wear such a short skirt.
Sorry it was a $640 toilet seat and a $436 hammer. Where do you think Independence Day got the kernel of truth from? Source: Here. Anybody with a grain of sense knows they were slush funds, I'm sure today that money still flows around its just not as well accounted for as a $436 hammer ;)
Shh.
"as much impact on our daily lives as Einstein's Theory of Relativity does " You need relativity correction for guidance system like GPS. So chance is, even relativity has an impact on the GP live.
C. Sagan : A demon haunted world:
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visit randi.org
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The language was asking for it.
And yet the very notion of "non-baryonic matter" challenges laws as fundamental and thoroughly-established as laws of gravitation
Since we already know lots about non-baryonic matter it's a little hard to see how the very notion challenges any laws of physics. Massive neutrinos, for example, are non-baryonic matter, and dark matter too. They exist. They don't account for the greater part of the dark matter that is inferred from observations, but they do exist.
The question I have is why so many people are so antagonistic to the very notion of dark matter, routinely calling the people who suggest it as an obvious and minimal move to explain the rotation curves of spiral galaxies (one type of dark matter, possibly baryonic) to the dynamics of galactic clusters (another type of dark matter) to the large-scale motion of the universe (possibly another type of dark matter) "arrogant" and the like.
We have an excellent theory of gravity that has withstood every experimental test in every situation, both strong-field and weak-field, short distances (Terrestrial corrections to GPS signals) and large distances (lensing). Furthermore, the hypothesis that there is dark matter is entirely consistent in precise numerical detail with general relativity and observations. That is, dark matter doesn't just explain things in a vague and hand-waving kind of way, it does so in a way that can be shown to be numerically consistent. That in itself is a test of GR too, and the way that MOND was eliminated from serious consideration: the dynamics of the Bullet Cluster are not consistent with MOND, but are consistent with GR plus dark matter.
So anyone attacking the dark matter hypothesis has to argue that there is some exotic phenomenon that just happens to be precisely consistent with GR plus dark matter, but is something completely different from GR plus dark matter. That is a rather fine-tuned sort of explanation. It could happen, but I'm not hopeful.
Dark matter as it stands is an extremely, possibly even overwhelmingly, likely hypothesis that is consistent in considerable numerical detail with GR and every empirical observation that has been made. You would have to be an idiot to call anyone who assumed it without further question "arrogant", unless you have an equally robust hypothesis to put up against it.
The real question for the dark matter hypothesis is the one you've alluded to in your final paragraph: what kind of elementary particles--if any--is the dark matter at various scales made of? That is where one of the leading edges of particle physics is right now. It is a thankless and difficult task, and the people pursuing it deserve more than to be called arrogant by know-nothings.
Blasphemy is a human right. Blasphemophobia kills.
And yet the very notion of "non-baryonic matter" challenges laws as fundamental and thoroughly-established as laws of gravitation.
Uh no it doesn't. Why do you think that? Who told you that? Gravitational theory itself has nothing to say on the subject of baryonic vs non-baryonic matter, and another thoroughly-established theory, the Standard Model, has predicted non-baryonic matter which has also been subsequently verified to exist (google up neutrinos, W and Z gauge bosons).
As the more detailed link on spacetelescope.com (EU hubble site) explains, this data actually confirms General Relativity in the relationship between lensing and red shift, plus confirms dark matter, plus confirms dark energy (accelerating universal expansion).
Multiple hypothesis and theories all come together and make a bunch of detailed predictions, that prediction is borne out to a T by actual experimental observation, that's called a phenomenal success.
Pretending otherwise is dogmatic in the extreme.
No your assumption that this causes all kinds of problems that it does not is dogmatic. Despite what you or whoever informed you thinks, the dark matter hypothesis is not inherently flawed. It's quite a good hypothesis, actually.
But further study is necessary, and the very true statement "we have no idea what it is" suggests to me that we don't even know if it really qualifies as matter. In that sense, calling it "dark matter" is misleading and potentially a case of multiplying entities. And having that pointed out should not embarrass or anger us.
It being matter is simply the leading hypothesis. And while it is understood that it might be something that isn't actually "matter" at all, that would be the case of needlessly multiplying entities. We know that weakly interacting matter exists. Adding in a completely new thing that acts like matter but isn't would require a very good theory and some very solid experimental evidence to back it up. Hypothetically possible at this point, but way more out there than it being matter.
In the meantime, the GP was not quite right, as we do have some good ideas what it could be, though of course we haven't confirmed it. The Neutralino is a leading candidate, and we may be closing in on confirmation of its existence.
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The picture looks strikingly like the graphics of outer space entities shown :-)
on various episodes of the original star trek. But without the story line
The article dated "March 26, 2010":
http://news.discovery.com/space/hubble-3d-map-universe-dark-matter.html
has a source dated 25-Mar-2010::
http://www.spacetelescope.org/news/html/heic1005.html
with this quote which explains everything:
The data was old, the analysis and imaging is new.
The 'Links' at the bottom include the new paper, and the old study. The old press release dated "7-errNoSuchMonth-2007":
"News Release heic0701 - First 3D map of the Universe's Dark Matter scaffolding"
http://www.spacetelescope.org/news/html/heic0701.html
Is the one described your original article:
http://news.bbc.co.uk/2/hi/science/nature/6235751.stm
The question I have is why so many people are so antagonistic to the very notion of dark matter, routinely calling the people who suggest it... "arrogant" and the like.
Personally I think the AC (perhaps unintentionally) nailed it -- it's part of a larger anti-science movement that considers the conclusions of science confusing, uncomfortable, or politically unattractive, and therefore seeks to discredit not just the particular theories but science in general. They do this by dressing up their ignorance with a thin veneer of scientific criticism in order to paint the professional scientists as the ones who are arrogant, ignorant, and arguing out of belief not evidence or reason.
Dark matter gets singled out because it sounds weird (especially if you know nothing about it) and like scientists are just making things up (especially if...). And if they're just making that up, then maybe they're just making up global warming, or evolution, or the age of the earth.
Even if they aren't against any of those particular theories, it's still just part of a general anti-science trend where people start with their conclusion -- the scientists are wrong because I don't understand them and I'm so smart that's not possible unless they're wrong -- and then work backwards to the kind of posts you see here. Accusing scientists of arrogance and dogmatism.
I mean look at the GP. They says it's "dogmatic in the extreme" not to admit that non-baryonic matter violates the law of gravity, clearly demonstrating that they are arguing out of ignorance and a belief that dark matter theory can't be true. The hypocrisy is astounding.
The world makes me sad. But data like this makes me happy. It's an exciting time in physics no matter what the doubters say and I can't wait to see where it leads.
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As was stated in that artical itself, and many times in the comments, that had no effect on the theory of dark matter. What they found were galaxies they knew had to be there, but they couldn't see. We found a 10 fold increase in the number of visible galaxies. This doesn't answer anything about Dark Matter, where the gravitational behaivor of galaxies doesn't seem to match the visible mass they contain. All we did was find more examples to review for the theory of Dark Matter, not dark matter itself.
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from the article: "However, we cannot directly measure the stuff as it doesn't interact with electromagnetic radiation (i.e. it doesn't emit or reflect any light)"
For like the billionth time, they don't know that! Why do they keep making that assumption?! It's 1000000000x more likely that it's just normal matter that doesn't happen to have measurable light (or other EM radiation) bouncing off of it at the moment. Just because we can't "see" it doesn't mean it's some magical, law of physics-breaking mystery material. That's like turning off all the lights in your room and then saying "well, logically all the matter in my room just disappeared into a different dimension or state of matter because that makes the most sense to me." Ugh, scientists can be such idiots sometimes. If you don't believe me, look up a history of idiotic assumptions about astronomy that were believed for absolutely no reason and then proven wrong.
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Isn't doubt what got us science in the first place?
Only when done sincerely, and with an understanding of the existing theories and the evidence for them, and thus their actual flaws.
We call those people "scientists". There are plenty of them who are exercising legitimate doubt yet following the evidence.
A "doubter" shares none of these aspects with scientists except for the doubt, and even then calling "doubt" is inaccurate because they are so often already convinced that the science is obviously wrong, and the scientists arrogant dogmatists for not admitting it.
At no point in my post did I suggest that dark matter is wrong.
Uh, you said that the leading dark matter hypothesis contradicted gravitational theory, which would mean one or the other was wrong, and you correctly noted that gravitational theory has been verified extensively, strongly suggesting you thought non-baryonic dark matter was ruled out.
You said claiming otherwise was "dogmatic in the extreme".
What I suggested was that people who insist it is right have a very poor grasp of the scientific method. At present it appears to be a very strong hypothesis. That's great.
Nobody is insisting that it is irrefutable. "Very strong hypothesis" is a much better description -- much stronger than most people, including you, are suggesting. The observation of the phenomenon we call dark matter is, at this point, essentially a fact, and that may be what the people are talking about.
I like to maintain a healthy degree of skepticism about any observational science that, for reasons of scale or scope, cannot (or has yet to) be proven in a laboratory setting.
That's great. Nothing wrong with that. But it would be helpful if you treated skeptics with skepticism, and looked into their arguments a little closer, or looked more into what evidence does exist for astronomical theory. You might be surprised to find out it's a lot more than you think, or were told by a "skeptic"!
Doubt is a good way to attack religion. Characterizing doubt as an attack on science is to turn science into a religion, and defeat its very purpose.
I'm not characterizing doubt itself as an attack on science.
I'm characterizing "doubt" that is founded in ignorance and the a-priori decision that the science must be wrong, as an attack on science. Which it is. Calling scientists arrogant and dogmatic because you don't understand the theory and because you can't believe they are right is not legitimate doubt. It's not useful scientific skepticism. It's hypocrisy.
While you certainly aren't as bad as many, since information you were unaware of appears to affect your opinion, this is still basically what you were doing -- calling every scientist working on non-baryonic dark matter a dogmatist for not admitting your (incorrect) argument proved them wrong. It's funny how you say doubt is a good way to attack religion, while simultaneously doing everything you can (including the topic of this post) to imply science is a religion and thus attack it via doubt.
Step one to being a useful scientific critic: Stop using arrogance and dogmatism to claim all scientists working in a particular field are arrogant and dogmatic.
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My mistake. It was my understanding that non-baryonic matter was still strictly theoretical and basically precluded its interaction with other matter except in gravitational terms. It may have been explained incorrectly to me, or I may have misunderstood. Thanks for clearing that up.
For future reference, when someone says that Hypothesis A is clearly contradicted by Theory B, when Theory B is something that anyone working on Hypothesis A would obviously be familiar with, and indeed requires to formulate their hypothesis, it's a pretty safe bet that the person telling you this is wrong, mistaken, or simply full of shit.
It's as bad as saying climatologists ignore the sun and its impact on climate cycles when in reality solar radiance is a key component of climate theories.
As tired as OP may be of defending the theory from ignorant people, one does not cure ignorance with anger and condescension.
Ignorance that does not want to be cured cannot be cured at all.
Since they'd already posted the explanation in at least one other thread, and this was the Nth "dark matter obviously doesn't exist cus I'm so smart" post -- EXACTLY the kind of person I was talking about being a giant hypocrite -- I think it's understandable. If that person wanted to acquire a clue, they had ample opportunity to do so.
Or are you saying that we should put up with infinite amounts of deliberately ignorant people arrogantly declaring themselves right and everyone who has actually studied the field wrong? With hypocrites calling scientists religious zealots when it is they who are arguing from belief and an unwillingness to admit they might be wrong?
Sorry that's just not in human nature, nor do I think it is helpful to lay down and be a doormat for these fools.
Thanks especially for the information on Neutralinos. I've read a fair bit about dark matter (for someone who is not even remotely a physicist, anyway) and I'd never heard of them.
You're welcome. That's a refreshing change of pace so I'll just say here's a decent place to start to learn more.
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Dark matter sounds really dull, hypothetical particles which only interact with gravity. This would mean about 23% of the Universe's mass is just boring stuff, while only 5% is interesting matter like us. But what if dark matter does have other interactions? If there were other forces of nature beyond the 4 we know of then dark matter maybe as interesting at normal matter. If these other forces did not interact with our form of matter we would not have found them yet. Maybe to dark matter, we are the dark matter. It would be cool if there was another "shadow universe" which we can hardly notice yet was just as rich as our own. Fun but probably not true.
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