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Error in CMB Interpretation? Implications?

  1. Jun 14, 2010 #1
    As noted in the thread "Dark Matter, On the Ropes?" there is disagreement with the observed velocity profile of spiral galaxies, the size of spiral galaxies' bulge, and the spiral galaxies' halo when compared to what theory predicts and what simulations with dark matter indicate.


    There is a list of the issues from a seminar presentation.
    Those discrepancies and the negative results for laboratory dark matter detection may indicate that dark matter does not exist.

    One of the observations which was believed to indicate that both dark matter and dark energy exists was the large scale variance of the cosmic microwave background radiation (CMB).

    This recent paper challenges that finding. If the authors' analysis is correct it appears to indicate that both dark matter and dark energy do not exist.

    Perhaps the new CMB data from the Planck satellite will help to resolve the issue.





  2. jcsd
  3. Jun 14, 2010 #2
    This is an expanded press release from the University of Durham that explains the findings and the associated theoretical issues.

    http://star-www.dur.ac.uk/~dph3us/cmb_press_release.doc [Broken]

    http://star-www.dur.ac.uk/~dph3us/cosmology.html [Broken]
    Last edited by a moderator: May 4, 2017
  4. Jun 14, 2010 #3


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    It seems to be an incredible stretch to go from

    "It will be interesting to see if a revised estimate of the WMAP beam profile then allows a simpler cosmological model to be fitted than LCDM."


    "If the authors' analysis is correct it appears to indicate that both dark matter and dark energy do not exist."
  5. Jun 15, 2010 #4
    Attached is another paper by the same authors and a discussion by a specialist in the field that explains why beam width changes the resultant and if the measurement is correct the conclusion as to whether the CMB analysis does or does not support the existence of dark matter and dark energy.

    The raw CMB signal measured by the Wilkinson Microwave Anisotropy Probe WMAP is adjusted for assumed foreground signals and is adjusted for beam width. (See figure 1 in this paper which compares the raw CMB signal to what we see in typical books and on the web.

    That mathematical change is very sensitive to the beam width which was determined by measurements with Jupiter. When the beam width is measured with distance astronomical objects a significantly wider beam width is found.

    Using the wider beam width the resulting mathematical resultant no longer supports dark matter and dark energy. That finding is supported by other recent papers which challenge the validity of dark matter and dark energy by different analysis.



  6. Jun 16, 2010 #5


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    A published paper does not lend credibility to a fringe perspective. Where is the blow by blow dismantling of the body of evidence supporting dark matter? My grandfather was an accomplished magician. I learned more watching his off hand than the one waving the wand.
  7. Jun 16, 2010 #6


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    It's irresponsible to make claims about which models fit and don't fit your data until you...ummm...do an analysis on which models fit and don't fit your data. They need to do a thorough Bayesian analysis, preferably with a model selection component, in order to make such claims.
  8. Jun 16, 2010 #7
    I am not sure what logical point you have.

    Increasingly sophisticated experiments have not been able to detect dark matter. Yes?

    The observed spiral galaxy morphology and rotational curve is not in agreement with simulations that use dark matter. Yes?

    The last argument, the last leg of the three legged stool, for dark matter has the CMB profile matches what was predicted.

    What we find is an independent measurement of a key parameter required for the data calculation invalidates the CMB resultant curve.

    The irrational statement that it is better to believe in something that does not exist than to have no theory at all, is comical. Believe in what every you want to believe in. Dark matter appears to be more a road block or a dead end, based on the analysis and observations.

    It is very normal for results to exactly match predictions when everyone believes the theory is correct. When new observations fundamentally challenge the theory, people look for and find errors in the original analysis. That has happened before and is what makes us human.

    If dark matter does not exist, it is back to the drawing board. The rotational anomaly for spiral galaxies still requires an explanation. As noted in the press release there has been the discovery of very large anomalous high temperature gas in the vicinity of clusters which is explaining the anomalous motion in clusters. There was a paper that showed that detailed analysis of Elliptical galaxy star motion did not support the existence of dark matter in the vicinity of elliptical galaxies.

    And I might add I do not support the theories that appeal to magic (close your eyes, tap your heels together three times and the universe will change as it is a hologram) such as the anthropological principal, or strings, or the 10th dimension as an explanation. Come back when there is a theory with predictions. There is obviously no fundamental base in physics. A quadrillion monkeys will not type out the correct theory. Guessing is not science.

  9. Jun 16, 2010 #8


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    You miss my point Saul. The point is not to debate the existence of dark matter, or the merits of including a dark matter component in simulations or parameter estimation analyses. The point is that the authors make a claim about the status of dark matter based on the increase in error bars of the CMB temperature and polarization maps without having actually done the analysis. Surely there's nothing illogical about requesting that someone actually do an analysis before making claims as to the outcome of that analysis.

    I don't see what the rest of your rant has to do with this thread though.
  10. Jun 16, 2010 #9
    I do not understand your comment. Shanks does calculations in his paper.

    Read the first page of his paper. Shanks has a problem with handwaving magic explanations. What you call rants appears to be a paraphrase of what Shanks states in the first page in his paper. (Let's leave his comments in the first page of his paper, as each bullet point deserves a separate thread.)

    His is asserting that a change in the beam profile invalidates the CMB calculations.


  11. Jun 16, 2010 #10


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    You are still watching the wand, Saul.
  12. Jun 17, 2010 #11


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    In which paper does he do the kinds of calculations I'm talking about? I'm not saying he does *no* calculations whatsoever. I'm saying he has not conducted a Bayesian parameter estimation/model selection analysis of the type necessary to make the claims he's making. I am not doubting the possibility that something is wrong with the beam smoothing used by WMAP -- I'm simply pointing out that I think his paper could be much improved by including such an analysis. Then he could concretely say something like: "I've removed dark matter from my CMB analysis, and I still obtain as good a likelihood as when I include it. This suggests that dark matter is perhaps an unneeded parameter in describing the physics of the acoustic peaks of the CMB". Or something like that.
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