Dark Matter, Dark Energy, Dark Flow ohh

  1. rhody

    rhody 765
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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:
    and
    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...
     
  2. jcsd
  3. Chronos

    Chronos 10,213
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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.
     
    Last edited: Mar 29, 2010
  4. PhanthomJay

    PhanthomJay 6,284
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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.
     
  5. rhody

    rhody 765
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    A little more detail in the flow is described here:

    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...
     
  6. marcus

    marcus 25,074
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    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.
     
  7. marcus

    marcus 25,074
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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.
     
  8. rhody

    rhody 765
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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:

    [​IMG]

    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...
     
  9. 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.

     
  10. rhody

    rhody 765
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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...


    [​IMG]
     
    Last edited: Apr 4, 2010
  11. 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 :)
     
    Last edited: Jan 16, 2012
  12. @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.
     
  13. 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.

    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.
     
  14. Drakkith

    Staff: Mentor

    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.

    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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