Jan 07 2007
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AAS Report #2: Dark matter and large scale structure
A note: I am attending a meeting of the American Astronomical Society in Seattle. I will blog as much as I can from this meeting, as there is a LOT of news coming out, as well as lots of fun and wonderful scientific geekiness. This particular blog entry is a bit long as I have to explain some relatively complex things to get to the point. I think most of my reporting will be somewhat less wordy. But no promises! I love this stuff, and I love to talk about it.
Today, astronomers released news about the largest and most detailed survey of the deep Universe ever made. It used telescopes in space and on the ground to make a huge census of matter across the Universe, from local regions out to a distance of about 6 billion light years. It’s called COSMOS, for the Cosmic Evolution Survey, the telescopes involved were Hubble, XMM-Newton, Spitzer, Keck, the Very Large Telescope in Chile, the Very Large (radio telescope) Array in New Mexico, and the Subaru observatory. It involved over 100 scientists from more than a dozen countries.
This survey is incredible: it mapped the location of more than two million galaxies over an area two degrees on a side on the sky– bigger than 16 full Moons. In the end, astronomers made what is essentially a three-dimensional large-scale map of normal matter (the stuff that makes up you, me, doorknobs, snakes, planes, everything we can see and touch).
Here’s a (very) small piece of the survey image from Hubble:
Click on it for a much higher-resolution version. It’s very pretty.
Amazingly, the map of galaxies made is not the most interesting part of this survey. What makes COSMOS unique is that using sophisticated techniques, the astronomers were also able to map out the location of dark matter as well! This is the stuff that makes up the vast majority of matter in the Universe, but which we cannot detect directly. It’s been known to exist for decades — it was first postulated in 1933 — but the evidence has been indirect. Dark matter still has gravity, and so we see it through its effects — galaxies surrounded by dark matter halos rotate differently than they would without them, and dark matter in clusters of galaxies reveals itself through the motion of those cluster members.
But a trick of relativity winds up betraying the presence of dark matter, too. As Einstein postulated, matter bends space, the way a heavy weight in a bed will warp the mattress. Light traveling though empty space will move in a straight line, but if matter is warping space, light will travel along the bent space as well. Imagine light from a distant galaxy is on its way to us. But between this galaxy and us is some large mass, like a clump of dark matter. The light from the galaxy will bend around the matter, and when it gets to us it will be slightly distorted, just as if the light has passed through a lens. This process, in fact, is called gravitational lensing (for more about this, see my writeup about the Bullet Cluster, image #4 in my Top 10 Images of 2006).
So astronomers can map out the location of dark matter by very carefully taking observations of large areas of the sky and painstakingly teasing out the distortions in the shapes of background galaxies. The observations need to be done from space because the background objects are faint, small, and very close together. Space-based telescopes can more easily see fainter objects than ground-based ’scopes, and have better resolution– they can separate closely spaced objects better. That’s why Hubble was used for this survey. In fact, the survey was massive: it took 10% of Hubble’s time over two years. It’s the biggest single project ever done by Hubble.
But Hubble has limitations. To get the dark matter location, the distances to many thousands of galaxies had to be found. This was done from the ground, using the Very Large Telescope and the Subaru Observatory, using a technique called photometric redshift. Basically, the galaxies were observed through many different color filters, and the brightness of a given galaxy in each filter can be used to determine its distance.
Armed with the distortion to the galaxies’ shapes and their distances, astronomers began to map out the location the dark matter.
Let me pause for just a second here– we’ve known about dark matter for a long time, but the problem is, the dang stuff is dark. It’s hard to see. People have been arguing over whether it even exists, yet now, not only do we know it’s there, we know where it is! This is an amazing advance.
There is one very big result you can see just by glancing at the observations:
The left image, in red, shows the location of normal matter on the sky. The right image, in blue, is where the dark matter sits. They match! It’s been theorized for some time that as the Universe cooled after the Big Bang, dark matter formed long filaments many millions of light years across. As that happened, normal matter would be attracted to it gravitationally. Today, the normal matter should trace the location of the dark matter. Now we can see this is true!
But it gets better. Because astronomers were able to see dark and normal matter at very large distances, they were able to track how the stuff changes over time. That’s because the farther away we look, the farther back in time we see — we see an object a million light years away as it was a million years ago. So by looking back far enough, you can actually see how stuff behaved in the distant past, billions of years ago.
And things have changed! Perhaps the most important thing astronomers saw in their data is that dark matter was smoothly distributed at times early in the Universe, and became clumpier as time wore on. They created an image to show this. It’s a 3D map of the dark matter:
You can think of the left hand side of the image being dark matter that is nearby, and the right side being farther away. But remember, distance=time. You can see that dark matter now (on the left) is clumpy, whereas dark matter was smoother a long time ago (on the right). Again, that is just what models predict. Over time, the smooth distribution of the matter in the Universe became lumpy as small ripples in the matter were amplified by gravity. In other words, any place where there was a little more matter had more gravity, and attracted even more matter. This process continued, until after billions of years we got our current Universe: clumpy, lumpy, and full of wonderful galaxies, stars, and planets.
The COSMOS survey data is incredibly rich, and will be mined for information for years to come. I have only touched on what was learned from it so far, and there is much more scientific knowledge lurking within it. And even now, astronomers are planning even more ambitious surveys of much larger areas of the sky. These surveys will refine the data taken already, and will also start to tackle dark energy, the mysterious force that appears to be accelerating the expansion of the Universe. We know even less about that than we do about dark matter.
As usual, the more we know, the more there is to know. There’s still so much to learn!
Great post, BA! You have the gift of being able to convey complex information and concepts in a way that the layman (such as myself) can understand. You are a true teacher and that’s about the highest compliment I know how to give.
PS; unlike some posters, I also love your more rant oriented posts. It’s all good, and always lots of fun.
Why isn’t it ‘bright yellow with purple spot matter’? That would make life easier!
Oh, and, um… am I right in inferring from the time stamp on your post that you haven’t reset your website to PST from daylight savings? Perhaps a switch to UT is in order?
Mind–and Universe–Expanding Stuff, Phil. Keep it coming!
Tom Epps
USNS Arctic
Persian Gulf
[…] AAS - The Many Ring Circus This is a crazy wonderful place. Over and over, I’ve heard people say this is the super bowl of astronomy. I’m not so sure that is the truth. I feel more like this is the 3 (or 5 or 10) ring circus of astronomy. In every ring there is a new group doing their thing and playing to crowds. I sometimes feel that my attention is getting pulled in every direction as the biggest, the brightest, the shiniest, the newest, all juggle and flip to the music of the stars. This is a place where the big teams present their big results. In fact, the COSMOS team presented dark matter and baryonic matter maps of the large-scale structure of the universe as a function of time. It was a truly tremendous result that Phil Plait wrote an excellent blog entry about at Bad Astronomy. I also caught a short interview with one of the team members, Richard Massey, which I’ll be incorporating into an Astronomy Cast episode in the next week or so. (As new results come out, I’ll be posting about them here.) And everyone is here. This is the place where everyone presents a poster presentation or a 5-minute oral presentation on their latest results (I’ll have my name on two presentations, one on Dorrit Hoffleit, and one on online education). This is a place every student comes to try to schmooze their way into the next stage in their career, whether it be a summer internship, graduate school, or their very first post doc. In fact, this is the place any one in search of a job comes to try and schmooze their way into the next step of their career (including me!). With such a large chunk of the astronomical community in one place, it’s possible to inadvertently run into people whose names usually only exist in things you read. Last night I hung out with Carolyn Collins Peterson, Phil, and other since education folks. Carolyn blogged a bit about it over at the Space Writer Blog. Earlier today I saw Alan Boyle of the Cosmic Log and became a momentary fan chick, thanking him for doing so to promote and help those of us little guys and gals doing independent blogs and podcasts. It seems every time I turn around there is a new neat person to listen too, learn from, and of course foist business cards on to and out of. And there are moments of weirdness. This Conference is at The Washington State Convention and Trade Center, and side by side with our astronomer conference is the The Seattle Wedding Show. This means that at one point a bunch of us were going up the escalator with NASA schwag while a “bunch of bride to beâ€s were coming down the opposite elevator with wedding schwag. It also means that at one point during a press conference on the Andromeda Galaxy’s extended halo, “Here Comes the Bride†could clearly be heard in the background. And sometimes people watching (all bride’s to be aside) is just fun. There are at least 4 people (including me) with unnaturally red hair lurking the conference. And there are the normal freaks and geeks of the community, with their crazy hats, or crazy hair, or just crazy craziness. Anyone who thinks we are a straight-laced community doesn’t know the right people. NASA’s Jeffery Hayes was throwing around the world, occasionally hurling the Earth at unsuspecting souls (he claims Women catch flying terra firma 80% of the time to men’s 20% of the time). People generally flew around grabbing up satellite paper models, posters, the occasional project emblazoned jump drive, and gobs of pens like kids in a candy shop were everything is free. Sure, to look at us, it’s a group of grey haired old men with a few women and flocks of undergraduates mixed in for flavoring, but all the flavoring is really spicy. So it’s a circus, and I am one of the side show freaks, but I’m in good company. Maybe tomorrow I’ll catch a cool release from a data contortionist or have a chance to see the bearded satellite. […]
AAS liveblogs…
Rob from Galactic Interactions is here as is Phil from Bad Asronomy I gather Sean and Jennifer are here also, not bumped into any of them. ‘Course my flight was late and I completely missed the opening reception. Phil……
Dr. BA, have you Seen this from CNN about the AAS?
Talk about sensationalizing a headline!
Sounds to me like Dr. Schulze-Makuch’s paper at the meeting said something to the effect of “life on Mars may have developed based on Hydrogen Peroxide, and if it did, the Viking Landers wouldn’t have noticed it, and if they happened to scoop some up in their experiments, they would have killed it with the experiments they used.”
Of course, CNN’s headline reads
Did you get to hear the presentation? What’s your take on it?
(Notice I dutifully checked here before posting on it this time!
)
Wow, the 3D image really brings it home how the dark matter clumped up over time. That’s a really big advance to actually see where the dark matter is, and how it evolved just as the models predicted.
Very very cool.
i didn’t see this coming at all. i was under the impression dark matter was such a distant mystery we’d be decades away from something like this.
GREAT Post!!!! As always thanks for sharing your great insight and knowledge!!!
[…] You can read a lot more about this at the HubbleSite press release and at Bad Astronomy. I will just include a pretty picture: […]
EGADS, JanieBelle, that is a pretty bad hack by the headline writer. Headline writers suck.
Phil, most of your article is pretty good, but one part confused me.
I don’t understand what this means. I get you’re trying to reference a square 2 degrees on a side, making it have an area greater than 16 full moons, but I don’t get how that fits into the mapping the whole sky.
So now all we have to do is figure out what the dark matter characteristics are. I think particle physicists are the next ones up to bat on this subject. Wonder if the big accelerators will provide any insight into these qualities? We’re pretty certain it’s not neutrinos so what the heck IS it?
Ah, the mystery continues,,,maybe the butler did the dirty deed,,,in the pantry,,,
GAry 7
I couldn’t agree more with j jonah jansen!
This stuff is why I’m here. I’m reading this during my lunch and the photos coupled with the verbal imagery are breathtaking, literally. The wonder of it all has left me lightheaded.
Keep it up Phil!
[…] Fortunately, I don’t have to go into details about the result, as others already have. Phil, Clifford, Rob, and Steinn have all blogged about the finding. Steinn’s post is, admittedly, pretty consise, but he wins points for breaking an even better story — Google is joining the Large Synoptic Survey Telescope consortium! Rob is even live-blogging the entire meeting, which is an heroic undertaking. (Yes, it’s true that he did bump into me up in Seattle, but I’m not there for the meeting! In fact I’m already back in LA. There are reasons to visit Seattle other than the AAS.) […]
How dense can dark matter get?
Ten to the power of negative fifteen grams per cubic meter is more than enough to have effects on large-scale structures in the universe.
[…] Phil Plait of BadAstronomy has a new very interesting entry: Dark matter and large scale structure. […]
Makes you wonder if we’ll find anything in the future which doesn’t interact with waves/particles of the electromagnetic spectrum or gravity.
Maybe it is at the other end of the scale , so to speak, but where does it leave ‘Black Holes’? How do they fit into the overall scheme of things?
Just thought I’d ask.
Ivan.
Ok, Dark matter… there’s lots of it… so how much does one Kg of Dm go for, what can we use it for, is it measured in pounds, metres or what. All I ever hear is you brainy guys saying there is a lot of it and you dont know much about it. Is this a goverment coverup ?
I don’t know where I head my head buried for the last few years but I didn’t even ralize the existance of dark matter had been confirmed before BA’s (very cool) top ten photo’s of 2006 post a bit back. And the more that’s posted about it the more mind blowing it gets. Dark matter effects normal matter gravitationally but in no other apparent way? That’s amazing. I wonder if it effects us in other ways we just don’t understand yet. And to the previous poster who wonders what particle physicists will do with it I ask: How the heck do we ever get our (proverbial) hands on any of it? To my knowledge particle accelerators haven’t ever produced anything nearly like this. Or even hints of it. I suppose I’ll keep reading and discover more, as we all do. Great post BA.
Ivan, as I understand it the current (largely experimentally verified) model of baryogenesis in the universe puts a limit on the maximum amount of normal matter (protons, electrons, neutrons, etc.), and this amount is less than all the matter in the universe. Since black holes are almost certainly formed by ordinary matter, they cannot account for the missing (non-luminous) matter.
I beg to differ with you Flak. The existence of Dark Matter has NOT been confirmed! Only the existence of unexplained gravitational fluctuations has been confirmed. I have yet to see anyone create, generate, capture or otherwise prove it’s existence.
The word ‘Virus’ was coined long ago to explain diseases for which there was no bacteriological explanation. Few believed in the existence of viruses UNTIL SOMEONE WAS ABLE TO POINT AT ONE! Dark Matter, Dark Energy and the recently “discovered” Dark Force are all the Viruses of Physics.
All I want to know is will one of them allow me to exceed the speed of light? If not, they are useless……lol.
I have a question about the analysis that might sound a bit weird, but it’s been puzzling me. How do they set a ‘zero’ to the distortions? I mean, they can find out \delta \rho, but how do they set \rho = 0? Do they just define the minimum of \rho to be zero? I’ll give you an analogy: take a plane slice of glass. It doesn’t cause any lensing, but the density isn’t zero. How do they get rid of this normalization? Also, a void in a non-zero density ( negative \delta rho) acts as a diffraction lens, no? Do you know if anything like this is observed? Best,
B.
Trying to understand dark matter:
It is said to have gravitational “mass” because that’s how it acts, but we don’t know its “composition,” i.e., whether there are elements or particles that we commonly talk about. And that’s why it’s dark, right? So we have an invisible gravity generator.
But does it have inertial mass? Are there frequencies of em radiation that it absorbs? Does it have collisions with normal matter?
These may be elementary questions that have been answered, but I didn’t want to assume that. All that I’ve heard is that “dark matter exists.” That’s not a very satisfying statement without a definition of dark matter in terms of how it’s different from regular matter (if it is).
The technology and science to produce that “map” sound wonderful!
Hey Phil - there’s a video on Youtube now showing the images from the Skepdude calendar. I just wanted to say - your picture? Made of 100% pure awesome.
Hope you’re having fun!
If dark matter exists, and that existence can be shown as this research seems to indicate, then I would think the next step would be to try and gather/make some, yes?
Hi Bill,
But does it have inertial mass
one of the best dark matter candidates are WIMP’s - weakly interacting MASSIVE particles…
Hi Squid,
then I would think the next step would be to try and gather/make some,
indeed, depending on what dark matter is, it might show up at the LHC, or alternatively there are experiments under consideration which would be able to detect dark matter directly even though it’s only extremely weakly interacting.
For more infor see also my post Dark Matter and references therein (don’t miss the comments).
Best,
B.
Does this mean that there are sub-atomic dark quarks?
Oldfart Says: …The existence of Dark Matter has NOT been confirmed! Only the existence of unexplained gravitational fluctuations has been confirmed. I have yet to see anyone create, generate, capture or otherwise prove it’s existence.
The word ‘Virus’ was coined long ago to explain diseases for which there was no bacteriological explanation. Few believed in the existence of viruses UNTIL SOMEONE WAS ABLE TO POINT AT ONE! Dark Matter, Dark Energy and the recently “discovered†Dark Force are all the Viruses of Physics.
Before viruses were visualized with the electron microscope we could ‘prove’ the existence of an infectious agent which was not visible with the optic limits of the time. We did this by showing the unseen ‘thing’ caused infection. It could be recovered and passed on again and again with each subsequent exposed organism becoming infected. Immunity could also be confirmed.
We have confirmed the existence of matter in space by its emissions of electromagnetic radiation along the entire spectrum. How do you know a gamma ray burst represents something occurring with normal matter? Maybe the bursts come from something which if observed after the burst, was no longer visible with any detection device?
So with that, here are 2 comments about your comments.
We accept as proof many kinds of evidence besides touching and seeing.
And, something exists we have evidence of but don’t know much about the nature of it. We have labeled it dark matter. Who cares if when we do discover the nature of it it turns out to be even odder than first thought? Maybe we will re-name it dark ether instead of dark matter. But the gravitational anomaly as you correctly call it is still evidence something we have labeled dark matter is in that spot.
It’s there, it exists. Prior to using gravitational lensing, the existence of dark matter was only theoretical based on the physics calculations which said there was not enough visible matter in the Universe for the calculations to be correct. Rather than an anomaly, it was still possible the math was wrong and gravity was the thing which was not as believed.
In other words, we can see something, we have labeled it dark matter, it isn’t Newton who was wrong. We have established dark matter exists, whether it turns out to be matter or an anomaly as you label it.
Feel free to correct my understanding of things here. I am not a physicist.
And I would add, gravitational lensing does indeed ’see’ things otherwise invisible. It would be like back-lighting an object and revealing its outline. If you accept infrared detection devices ’see’ things, why be so reluctant to accept gravitational detection is evidence as well?
Pah. Dark matter is just bent space. Leave enough ordinary mass in one place long enough and space/time can be permanently warped. A black hole can actually put a kink in it. There’s a certain amount of hysteresis.
Space is clumpy because it’s dented.
That’s pretty slick… but… why does the term “phlogiston” come to mind every time I hear about dark matter?
It’s also interesting that the physicists aren’t falling over themselves in a rush to tell us what dark matter is. [There are more things in heaven and earth, Horatio, than are dreamt of in your philosophy]
Higgs bosons may prove snooty, less elusive than reclusive, preferring the exclusive company of their own kind and disdaining interactions with lesser particles. Might there even be elder, heavier, haughtier such?
“Pah. Dark matter is just bent space. Leave enough ordinary mass in one place long enough and space/time can be permanently warped. A black hole can actually put a kink in it. There’s a certain amount of hysteresis.
Space is clumpy because it’s dented. ”
Could you elaborate on these statements? How does the space get permanently warped and how do you prove such an assumption?
“Let me pause for just a second here– we’ve known about dark matter for a long time, but the problem is, the dang stuff is dark.”
Dark matter is not dark, Phil, it’s transparent. Despite that, it was a great read, thank you a lot!
Until recently the best alternative to “dark matter” has been something called “modified Newtonian gravity”. The basic idea behind it is that on very large distance scales the inverse square law that describes the gravitational force (both in Newton’s and Einstein’s gravity models) changes slightly. The last I head about it this modified gravity law worked pretty well in a classical situation but had not been made consistant with relativity.
However, with this level of detailed mapping of dark matter locations, I wonder if modified gravity laws would still be consistant with the observations, or can we give up on that one completely now? Anybody up on the latest literature on this?
Balstrome Says: “Ok, Dark matter… there’s lots of it… so how much does one Kg of Dm go for, what can we use it for, is it measured in pounds, metres or what. All I ever hear is you brainy guys saying there is a lot of it and you dont know much about it. Is this a goverment coverup ?”
Obviously the fault of the Bush administration…
Flak Says: “Dark matter effects normal matter gravitationally but in no other apparent way? I wonder if it effects us in other ways we just don’t understand yet.”
Yes, it surrounds you with “cosmic energy” and affects your very personality. Soon people will be able to predict the events in your life by deterimining the position of the dark matter in the sky. They’ll have daily predictions for you every day on the comics page.
- Jack
Carnifex Says: “‘Leave enough ordinary mass in one place long enough and space/time can be permanently warped. A black hole can actually put a kink in it. Space is clumpy because it’s dented.’
Could you elaborate on these statements? How does the space get permanently warped and how do you prove such an assumption?”
I believe it was a joke, just like my last post.
- Jack
Good one Phil! I linked to your explanation from my blog; ya done good!
I think Carnifex had a reasonable statement that there was room for doubt about dark invisible matter being proved. I think with all the additional data and the gravitational lensing, I’m going to go with the evidence it is there and does exist. But the dented space hypothesis is a reminder there may be other explanations not yet thought of.
Invisible matter isn’t correct either. Unless you take the literal definition cannot be actually seen. If we make a false color image of the gravitational evidence we can see the dark matter just as we can see a false color image of incoming electromagnetic data outside the visible range.
It’s dark because it doesn’t interact with light.
Dave - the recent TeVeS theory extends MOND to be relativistic, and I’d think (although it’s not my field) that the DM tracing the light would make explaining it with MOND-type theories easier. Far harder is where the mass and the light don’t go together (see past BA blogs for the example, whose name escapes me) - but the MOND proponents claim that this can be explained with neutrinos (an ‘allowed’ DM in that theory) rather than needing CDM, so the alternatives to DM are still alive.
Talking of alternative theories, has anyone in Seattle talked to the guy with the ‘alternative theory vs Big Bang’ stand? in the middle of the main hall?
The jape about bent space was mine. It’s really not that much different than saying there’s a bunch of unobservable massive stuff out there, since (at least in the traditional theory) gravity is equivalent to the warping of space.
To attribute memory or hysteresis to space itself would, I suspect, also impute mass, thus begging the question. It’s really an ether hypothesis, where the ether is something like taffy.
In contrast, dark energy (to my limited understanding) could be just a coefficient in the gravity equation, Einstein’s cosmological constant.
There’s also the issue of where all the antimatter went. According to scripture, matter and antimatter should initially have been created in equal proportion, yet in the observable universe antimatter is essentially absent. Perhaps, rather than being immediately eliminated moments after the creation of the universe, the antimatter collapsed into innumerable small black holes. (This, though it might explain the abundance of dark matter, wouldn’t explain its shyness.)
How do we really know that the next galaxy over isn’t antimatter, though?
How do we really know that the next galaxy over isn’t antimatter, though?
I guess we’d see annihilation effects around it. Even the space between galaxies isn’t empty.
[…] For more information on this survey, visit the COSMOS home page, the Hubble press release page, and the Bad Astronomy site which has details on the results. […]
The MOND theory was developed so that it would conform to the Tully Fisher law which says that the total luminosity of a galaxy is proportional to its highest orbital velocity.
We cannot believe that the Tully Fisher law “says what it says it means”. We have to believe that mass has some inherent yet-to-be described property that transmits itself through a vacuum and attracts neighboring mass or warps space.
The light pressure studies tell us that light is repulsive not attractive as implied by the Tully Fisher law. Guess what I have performed numerous experiments that indicate that the “radial spreading of infrared luminosity” is attractive. I can get as much as 10% increase in weight with a hot plate heating element attached to a convex-up colander.
Furthermore, my luminosity-based gravity theory provides a “close to experience” explanation for the higher-than-expected rotation curves of galaxies which make the dark matter “superfluous” (in the immortal single word of Einstein who came up with a theory that did away with the “luminiferous ether” by making the results of the speed of light studies mean what they said they meant).
[…] Carnivals like this one seem to be gaining popularity, a welcome thing because they offer pointers to sites I hadn’t known about, and the topics are always interesting. Good coverage of the American Astronomical Society meeting shows up here, along with work on dark matter, the Antikythera Mechanism, and a wonderful explanation of light cones and Einsteinian relativity. I’m pleased that Philosophia Naturalis includes two recent posts on the James Webb Space Telescope from these pages. […]
“Balstrome Says: “Ok, Dark matter… there’s lots of it… so how much does one Kg of Dm go for, what can we use it for, is it measured in pounds, metres or what. All I ever hear is you brainy guys saying there is a lot of it and you dont know much about it. Is this a goverment coverup ?â€
Jack Hagerty says..”Obviously the fault of the Bush administration.”
Give these posters time, they’ll figure out a convoluted way and use mental gymnastics to assign blame to Bush. Seemingly everything that is wrong with the world is Bush’s fault, dontcha know!
Meanwhile, over a thousand surveys went out and only 10% came back with stated acknowledged pressure from Bush’s administration officials. You would think that if the pressure was so pervasive, there would be a response rate of a lot more than 17%! But, alas, only 60% of the lowly 17% responders said that there was.
This is all that it took for the BA minions to pounce on Bush. They came to this conclusion with a total lack of due diligence because it must be evaluated on a relative basis, not an absolute one. How does this 10% compare to prior administrations? There is seemingly no data on that, so one can not make a reasonable conclusion. But, never fear, illogical Bush bashers are here and damn anything relative.
Just curious. Have you ever heard any good arguments why dark matter cannot be plain old cold plasma, gas, dust, etc. that has not managed to condense into self gravitating accumulations?
Being only a layman with an interest in the subject, I’m not even sure how to present an idea on dark matter that I’ve had for a very long time. But in a nutshell:
Dark matter is merely anti-matter. As anti-matter, it creates anti-gravity and other forms of anti-energy. It seems that an anti-matter universe exists in a commingled way with our material universe. There are anti-stars, anti-planets, anti-galaxies, even anti-light. The reason we cannot see the ‘dark matter’ is because gravity and anti-gravity will ‘push’ against each other as opposed to ‘pull’. Even anti-light approaching earth would be pushed away by the gravity of our galaxy, sun, earth and even individual atoms. Even if some form of anti-radiation were to reach our region of matter and actually come into full contact, it would be annihilated. The meeting of matter/energy and anti-matter/anti-energy would simply cancel each out of existence. This is largely avoided due to the repulsion of the two opposing forms of matter.
The idea of anti-matter and, therefore, anti-gravity, may be a possible explanation for the continued expansion of the universe.
Any comments on this line of thinking would be greatly appreciated.
Lance Knoechel
lknoechel@cinci.rr.com
well but milk woudnt stay forever in the fridge that is acording to the cosmlagistic theory
“Dark Matter”! Good description if you have no idea what it is. Or, if it exists. Does anybody have any postulations as to the composition of “Dark Matter”. Is sort of like a cross between Jello and window putty? What would it taste like? Was it created from the “BIG BANG” and then went on to coalesce into stuff that we can see? Why isn’t there any dark matter close to the earth? Why would it only exist a real long ways away? Maybe if we stopped concentrating on such huge distances, we might discover some close by. Why not have a good look around in New York City? They’ve got everything else there. And on this expansion of the universe thing. Just what in hell is the universe expanding into if that is not in itself, The Universe? How do we know it is expanding at all. Maybe it is contracting from another direction. That’s the problem with scientists. They have allowed ethnocentricity (does anybody know how to spell that) to color their thinking. Where is the center of the universe? Maybe we are the ones who are way the hell out toward the edge. Edge! Now that gets me going. Does this mean that the celestial objects that are caught up in the accelerating expansion are going to eventually bounce of a cosmic wall? If the universe started with a big bang, where did the stuff to go “Bang” come from and how is it that there was a “SPACE” in which the “Big Bang” could take place.
Some of you may have guessed by now that I do not know squat about astroni
my. Actually, I wouldn’t even be bothering with this were it not for the fact I’m trying to avoid kitchen chores by pretending to be working.
Have a happy
Dark matter, as described in current physics, consists of particles that don’t interact with matter and light as we know it, or does so very weakly, with the exception of gravitation. The concept of dark matter was originally introduced to explain why galaxies rotate as fast as they do without all the matter flying off. There either was a flaw in Newton’s law of gravity or there was matter that couldn’t be seen. MOND, which stands for MOdified Newtonian Dynamics, was the competing theory to dark matter, and it required that gravitational effects drop off in quanta at extreme distances that allowed for a greater apparent effect. The math was quirky and no one seemed comfortable with it. Anyway, dark matter as a blanket term can also refer to cold normal matter like brown dwarves. The entire reason for dark matter is explain where the “rest” of the matter in the universe resides.
[…] amazing aspects of looking into deep, deep space is that the path there is tortured and twisted. Space itself can be distorted by mass; it gets bent, like a road curves as it goes around a hill. And like a truck that must follow that […]
LoL I love Astronomy the colors are so lovely that if you over lay them you would get a good 3D image with the right glasses. lol As to the research ranting or not it is still very interesting. ^_^
[…] Team of researchers in Italy claims to have directly detected dark matter Short background: we know dark matter exists. We also know it must be made up of particles that are very difficult to detect (or else we’d […]