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Dark Matter, Dark Energy, Dark Flow... ohh...

by rhody
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rhody
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Mar28-10, 08:41 AM
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From National Geographic: Daily News, by John Roach, March 22, 2010

New Proof Unknown "Structures" Tug at Our Universe

As if Dark Matter and Dark Energy aren't weird enough, now it seems we have verified proof of "Dark Flow".

From the article:
Dark flow" is no fluke, suggests a new study that strengthens the case for unknown, unseen "structures" lurking on the outskirts of creation.
In 2008 scientists reported the discovery of hundreds of galaxy clusters streaming in the same direction at more than 2.2 million miles (3.6 million kilometers) an hour.
This mysterious motion can't be explained by current models for distribution of mass in the universe. So the researchers made the controversial suggestion that the clusters are being tugged on by the gravity of matter outside the known universe.
Now the same team has found that the dark flow extends even deeper into the universe than previously reported: out to at least 2.5 billion light-years from Earth.
After using two additional years' worth of data and tracking twice the number of galaxy clusters, "we clearly see the flow, we clearly see it pointing in the same direction," said study leader Alexander Kashlinsky, an astrophysicist at NASA's Goddard Space Flight Center in Maryland.
and
But the clusters are also moving relative to the background radiation, so the scattered light gets distorted further by the Doppler effect. This distortion appears in the form of temperature shifts in WMAP data, which can reveal the clusters' direction and speed.
"It is very difficult to isolate [the temperature change] for each individual cluster," Kashlinsky said, so the original study had examined 700 clusters.
The new study is based on the collective motion of about 1,400 galaxy clusters, and seeing dark flow with the greater number of clusters gives the researchers more confidence in their result.
I have a layman's question for you astrophysicist's out there, is this behavior possible because of increased accuracy or simply a larger sample in the WMAP data as reported ?

Second, are there areas that attract large sections of our Universe in addition to the one observed, and in different directions ?

As always, thanks in advance...

Rhody...
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Chronos
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Mar29-10, 04:21 AM
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I view this paper as speculative and unsupported, thus far. Cherry picking a few groups of galaxies with odd directionality is unconvincing.
PhanthomJay
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Mar29-10, 06:39 AM
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The controversial suggestion that the clusters are being tugged on by the gravity of matter outside the known universe, is nothing new. It was postulated by the Brane theorists years ago, as noted by Hawking in his masterpiece book "The Universe in a Nutshell", whereby ultra short gravity waves from another universe may be able to penetrate (through black holes, where such waves may exist) the miniscule higher order spatial dimensions of our universe (which light cannot, so the other universes are forever hidden from our view, but its matter can be detected through the penetrating gravity waves). Whether it is a good theory or not, I don't know, but it seems to make sense, or at least as much sense as the other theories.

rhody
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Mar29-10, 09:48 AM
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Dark Matter, Dark Energy, Dark Flow... ohh...

A little more detail in the flow is described here:

Like some kind of massive cosmic toilet bowl, the multitude of galaxies that populate the known Universe are swirling inexplicably toward a tiny 20-degree plane of deep space. At least, that's what astrophysicist Alexander Kashlinsky discovered in an incredibly controversial paper published in October 2008. Put simply for we laypeople, the paper suggests that way out in the cosmos—beyond Tatooine and idiotic Ewoks and Caprica Six's curves—lay a chunk of matter so beyond our understanding that it is actually pulling the observable universe toward it at 600km/s.
I did the math and 600km/s = 2,160,000 km/hr = 1,342,162 mph, pretty quick and toward a 20 degree plane of deep space. The next question I have is the plane concave due to the warping that occurs due to the gravity. I should qualify the last statement, I should have said that (if gravity is involved). If someone has a picture of what is proposed it would clear up some of the questions that I think we all have at this point.

Rhody...
marcus
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Mar29-10, 04:08 PM
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Quote Quote by rhody View Post
From National Geographic: Daily News, by John Roach, March 22, 2010

New Proof Unknown "Structures" Tug at Our Universe

...
Popular accounts like the one in National Geographic can be misleading, so for comparison here is the March 2010 Astrophysical Journal article which the NatGeo news item was based on:

http://arxiv.org/abs/0910.4958

Kashlinsky's initial announcement in 2008 was met with skepticism and one or more apparent errors were pointed out. So far I don't think we can say that Kashlinsky is wrong or that he's right.

If it's right, well, it would be a big deal. A lot of people would want to get on the bandwagon and make their own observations. This hasn't happened yet AFAICS, but it could happen.

Kashlinsky's claims have changed, since 2008. Since his analysis was challenged he has gone back and got more data and analyzed everything more carefully. And he still claims a flow but some of the numbers look different.

Here's what Kashlinsky himself says in the abstract:
"...approximately constant velocity out to at least 800 Mpc. The significance of the measured signal peaks around 500 Mpc, most likely because the contribution from more distant clusters becomes progressively more diluted by the WMAP beam. We can, however, at present not rule out that these more distant clusters simply contribute less to the overall motion."

500 Mpc = 1.6 billion lightyears
800 Mpc = 2.6 billion lightyears

This is in terms of proper distance, so this is the size now of the patch of universe which is alleged to be drifting---collectively moving in some direction---relative to the Background.

He can't rule out that the collective drift only involve the relatively small patch extending roughly out to 2 billion lightyears. He claims statistical significance out to 2.6, but significance peaks at 1.6, and it could be that the farther out stuff is simply not moving much with the flow.

So it's possible that Kashlinsky won't convince a significant number of his colleagues and the idea will die. And it's also possible that he will convince people that there is this localized drift, extending out roughly 2 billion lightyears in one or more directions.

By the same measure of distance, the observable universe extends out over 45 billion lightyears in all directions. So even if Kashlinsky can establish that the drift is real, he is so far only saying something about a SMALL BLOB that is only around 4% of the present radius of the observable, which means 0.0006 of the volume. Less than one thousandth of the volume of that part of the universe which we are currently observing.

Also the speed he claims is comparatively small, compared with estimated rates of expansion. He claims 500 km per second. But the speed of light is 300,000 km/s. So he is talking about a drift which is only about one thousandth of the speed of light.

But most of the galaxies which we observe are currently receding (according to Hubble law) at rates in excess of the speed of light. So 1/1000 of c is not automatically a big deal.
Our own galaxy, in fact, has already been show to have a motion relative to Background which is about that rapid. 500 km/s is not unusual for the disorganized random motion of galaxies and clusters of galaxies---it is kind of normal. What would be surprising, and interesting, if Kashlinsky can establish it convincingly, is a large scale collective motion all in approximately the same direction!

I've been watching this since Fall of 2008 and so far I'm taking a wait-and-see attitude.

Glad to see it got into NatGeo. But still have to wait and see.
"Dark Flow" is a bit on the jazzy side.
Have to see what Ned Wright says about Kashlinsky et al series of papers about this.
marcus
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Mar29-10, 04:15 PM
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Here's what Ned Wright said back in September 2008

"Dark Flow Detected - Not!

24 Sep 2008 - Kashlinsky et al. (2008) have claimed a detection of a bulk flow in the motion of many distant X-ray emitting clusters of galaxies. Unfortunately this paper and the companion paper have several errors so their conclusions cannot be trusted. A technical discussion of these errors can be found here."

I haven't copied his links. To get the links go here, and scroll down to the headline:
http://www.astro.ucla.edu/~wright/cosmolog.htm

Wright may have changed his mind after seeing the more recent papers by Kashlinsky's group, but I haven't seen any indication of this. If anyone sees some evidence that the Kashlinsky idea of a bulk flow in gaining acceptance by cosmologists, please let me know.
rhody
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Mar29-10, 05:34 PM
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Thanks Marcus,

Your description, distances, etc... put everything in context that a layman like myself can understand. I will reiterate it to make sure I got the gist of what you said.

The galaxies being observed are between 1.6 - 2.6 billion light years is "suggested to be moving" at one thousandth the speed of light in some direction and has an area of about 4% of the visible Universe. I got that part, I think.

This is reflected in the image below, correct ?

See link and image below:


Watch this video here of how CMB data is collected. Every time a rotation was made a swath of the visible Universe was sampled at some rate/sampling frequency, right ?

I don't know what the aperture of the instrument being used to collect the data, or if there is any correlation (if any to the 4% swath being reported). Having said that, unless other independent measurements are taken of the suspect area and analyzed for the suspected anomaly, then I totally agree, it is suspect. And this is regardless of what other math errors were reported and then found in the data.

Could something like an intense GRB (they are small cone shaped objects) from what I have learned have short lifetimes, 2 seconds to something like 2 minutes for a really big one, suddenly have (blinded or added extra energy to the measurement sweep) as the instrument made it's pass, sampling the data ? As I look at the elliptical shape of the figure above, it does appear to be in what could be thought of as a sampling band. Watch the video again to see what I mean. If not a gamma ray burst, then what other type of anomaly could explain what we are seeing, you are the expert, and I would like to hear what other celestial events could explain it.

If it is in fact, just that, an anomaly, the odds are pretty good it would not be seen a second time, and a second sampling, by a different instrument should prove it one way or another.

Rhody...
ViewsofMars
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Mar30-10, 11:07 AM
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Regarding the issue of Dark Flow, Goddard Space Flight Center published an article on March 10, 2010 entitled Mysterious Cosmic 'Dark Flow' Tracked Deeper into Universe.

Distant galaxy clusters mysteriously stream at a million miles per hour along a path roughly centered on the southern constellations Centaurus and Hydra. A new study led by Alexander Kashlinsky at NASA's Goddard Space Flight Center in Greenbelt, Md., tracks this collective motion -- dubbed the "dark flow" -- to twice the distance originally reported.

"This is not something we set out to find, but we cannot make it go away," Kashlinsky said. "Now we see that it persists to much greater distances -- as far as 2.5 billion light-years away." The new study appears in the March 20 issue of The Astrophysical Journal Letters.

The clusters appear to be moving along a line extending from our solar system toward Centaurus/Hydra, but the direction of this motion is less certain. Evidence indicates that the clusters are headed outward along this path, away from Earth, but the team cannot yet rule out the opposite flow. "We detect motion along this axis, but right now our data cannot state as strongly as we'd like whether the clusters are coming or going," Kashlinsky said.

The dark flow is controversial because the distribution of matter in the observed universe cannot account for it. Its existence suggests that some structure beyond the visible universe -- outside our "horizon" -- is pulling on matter in our vicinity.

[look at images on-line]

Cosmologists regard the microwave background -- a flash of light emitted 380,000 years after the universe formed -- as the ultimate cosmic reference frame. Relative to it, all large-scale motion should show no preferred direction.

The hot X-ray-emitting gas within a galaxy cluster scatters photons from the cosmic microwave background (CMB). Because galaxy clusters don't precisely follow the expansion of space, the wavelengths of scattered photons change in a way that reflects each cluster's individual motion.

This results in a minute shift of the microwave background's temperature in the cluster's direction. The change, which astronomers call the kinematic Sunyaev-Zel'dovich (KSZ) effect, is so small that it has never been observed in a single galaxy cluster.

But in 2000, Kashlinsky, working with Fernando Atrio-Barandela at the University of Salamanca, Spain, demonstrated that it was possible to tease the subtle signal out of the measurement noise by studying large numbers of clusters.

In 2008, armed with a catalog of 700 clusters assembled by Harald Ebeling at the University of Hawaii and Dale Kocevski, now at the University of California, Santa Cruz, the researchers applied the technique to the three-year WMAP data release. That's when the mystery motion first came to light.

The new study builds on the previous one by using the five-year results from WMAP and by doubling the number of galaxy clusters.

"It takes, on average, about an hour of telescope time to measure the distance to each cluster we work with, not to mention the years required to find these systems in the first place," Ebeling said. "This is a project requiring considerable followthrough."

According to Atrio-Barandela, who has focused on understanding the possible errors in the team's analysis, the new study provides much stronger evidence that the dark flow is real. For example, the brightest clusters at X-ray wavelengths hold the greatest amount of hot gas to distort CMB photons. "When processed, these same clusters also display the strongest KSZ signature -- unlikely if the dark flow were merely a statistical fluke," he said.

In addition, the team, which now also includes Alastair Edge at the University of Durham, England, sorted the cluster catalog into four "slices" representing different distance ranges. They then examined the preferred flow direction for the clusters within each slice. While the size and exact position of this direction display some variation, the overall trends among the slices exhibit remarkable agreement.

The researchers are currently working to expand their cluster catalog in order to track the dark flow to about twice the current distance. Improved modeling of hot gas within the galaxy clusters will help refine the speed, axis, and direction of motion.

Future plans call for testing the findings against newer data released from the WMAP project and the European Space Agency's Planck mission, which is also currently mapping the microwave background.

Related Link - Scientists Detect Cosmic 'Dark Flow' Across Billions of Light Years (2008 story)

http://www.nasa.gov/centers/goddard/...10/10-023.html
rhody
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Apr4-10, 03:00 PM
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I thought this image obtained from ViewsofMars post above, thanks, BTW, helps to further differentiate what is being observed. This link gives detail about the Herschel (l) and Planck telescopes (launched May 2009 from the same Ariane rocket (scroll down to watch the video). Herschel will study far IR wavelengths and will build a complete skymap (can peer through dust clouds of the early Universe) to reveal the structure of that period, whereas the Planck telescope will map the microwaves region, and one would hope will see and corroborate or prove false the mystery of the current data, suggesting "cosmic flow"

I found Max Tegmark's CMB Data Analysis Center (his site is a liitle out of date 1999, but appears to be worthy to have a look at). From reading about him on PF from time to time, correct me if I am wrong, he is considered somewhat of a maverick, and not one to follow the mainstream. That being said, the process of collecting and analyzing the data appears to be (from an outsider layman looking in) complex, time consuming, and open (to the possibility) of the introduction of human or in the coding required.

Do the steps and processes laid out by Max Tegmark (generally) follow the same protocols and used by Kashlinsky in his analysis of the data ? The reason I am asking this question is that is the world where I work, we always use multiple forms of verification to analyze signals. Each system cross checks the other and informs the user's where anomalies in the acquired data and/or processed output occur.

I know I have bitten off much more than I can chew here, but at the very least, I think it would not be too much to ask for a sentence or two about the process and stages used to analyze the CMB data.
Let's use Tegmark's approach as a start.

BTW, FYI, Marcus, at the bottom of Tegmark's page, under Other CMB Links, is a link to Ned Wright's cosmological tutorial.

Rhody...


NadJ
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Jan16-12, 08:24 AM
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Recently saw a documentary about dark matter, energy and now flow. What puzzles me is this: When scientists dissect an animal brain to understand how it works, they label occurrences as being due to complex (not accurately measurable and decipherable) electrical interactions or plain old simple cell reactions. In the latter case, changes, often hormonal in nature, cause cells to reposition themselves, shape shift, rejuvenate, multiply and die.

Yet when we peer at the massive universe which has far more time to "evolve" we hesitate to label some of the unexplainable things as being due to the universe’s equivalent of a complex (dare I say wireless) network of electrical communication or due to some kind of unknown “hormonal” force carried by space winds or light itself!

Of course I understand the term “dark” is applied to that which is unknown but I fear that the atheist agenda is polluting the water as far as future discoveries go as no physicist worth his ilk wants to be associated with a universe that looks, sounds and behaves remotely intelligent. Just putting the cat amongst the pigeons. Go easy on me :)
Fuzzy Logic
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Jan16-12, 11:26 AM
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@NadJ

What is your basis for such a hypothesis? What would it explain and how?

Being atheist has nothing to do with scientific observation. It just means we don't automatically conclude that everything we can't understand is divine or intelligent.

Even if the universe were intelligent, an atheist will rightly point out that intelligence is not proof of any god. I'd like to think that humans are intelligent, yet I have absolutely no issues reconciling that. Intelligence != divine creation.

Anyway, what you are missing is that biology evolves into novel and unique systems through reproduction and random mutations (non-linear change). Evolution in the sense of the universe is only referring to the passing of time (linear change). There is no reproduction and no random mutations in the mechanics of the universe that would facilitate an evolutionary intelligence. If somehow the universe is intelligent, it didn't evolve to be, it just is.
H2Bro
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Jan17-12, 06:31 PM
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Yet when we peer at the massive universe which has far more time to "evolve" we hesitate to label some of the unexplainable things as being due to the universe’s equivalent of a complex (dare I say wireless) network of electrical communication or due to some kind of unknown “hormonal” force carried by space winds or light itself!
Well, I daresay scientists tend to explain novel phenomena in terms of the concepts and laws that appear relevant considering the variety of phenomena itself. For the same reason a neuroscientist would not explain a new brain structure in terms of dark matter, dark energy, and multiple universes, an astrophysicist is equally unlikely to import concepts from neurology to explain astrophysical phenomenon.

Anyway, what you are missing is that biology evolves into novel and unique systems through reproduction and random mutations (non-linear change). Evolution in the sense of the universe is only referring to the passing of time (linear change). There is no reproduction and no random mutations in the mechanics of the universe that would facilitate an evolutionary intelligence. If somehow the universe is intelligent, it didn't evolve to be, it just is
I don't think "biology" evolves into novel and unique systems through non-linear changes, rather organisms do (hate to get semantic). But acknowledging that indicates the laws of biology are as constant as those of astrophysics. evolution I would think can be vaguely defined as the emergence of complexity from initially simple conditions through multiple iterations of path-dependent processes under invariant laws.

Therefore structures in space can, indeed, "evolve" by undergoing progressive changes that create complexity from initially simple conditions like star systems forming from more dispersed clouds of gas. I think the word "evolution" can be applied equally to astronomy and biology, in that sense.

But, I am a layman, and those more qualified might think differently :)

/way off topic.
Drakkith
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Jan17-12, 07:14 PM
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Quote Quote by NadJ View Post
Yet when we peer at the massive universe which has far more time to "evolve" we hesitate to label some of the unexplainable things as being due to the universe’s equivalent of a complex (dare I say wireless) network of electrical communication or due to some kind of unknown “hormonal” force carried by space winds or light itself!
You are comparing EM Radiation and Gravity to the way a brain works? The two aren't even remotely related except in the broadest possible sense. As for some unknown force, we can't begin to speculate until we have something telling us we are missing some piece of the puzzle, which is exactly why we think dark matter and dark energy exist.

Of course I understand the term “dark” is applied to that which is unknown but I fear that the atheist agenda is polluting the water as far as future discoveries go as no physicist worth his ilk wants to be associated with a universe that looks, sounds and behaves remotely intelligent. Just putting the cat amongst the pigeons. Go easy on me :)
The label "Dark" is applied because Dark Matter is not visible to us. Dark energy, which was theorized later, also took the label because we cannot "see" it.


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