Reactions to the Dark Matter Debate and Another One in German TV

24 November 2010 by Marcel S. Pawlowski, posted in General

While the official video podcast of the Bethe Colloquium "Dark Matter, a Debate" is not available yet, there nevertheless have already been some reactions send via email or posted on astronomy blogs. Some are based on the live blog of the debate. In addition to that, there will be a discussion about Dark Matter in German television this thursday.

Reactions to the Dark Matter Debate

Before the debate, a number of people labeled it as a "MOND vs. Dark Matter" debate, which is simply a wrong statement. This is not the question we as scientists have to ask today. The real issue at hand is the question whether we understand LCDM as being falsified or not. This is independent of the possible existence of an alternative and its successes or failures. Unfortunately, in his report of the debate, Daniel Fisher, who was there himself, also presents it as one between a Dark Matter and a MOND advocate. He shares his impressions (in German) on his Blog Skyweek Zwei Punkt Null.

In contrast to that, Nando Patat, astronomer at ESO, who posts his thoughts on the matter in a post titled "We do not understand nature, we measure it", puts more emphasis on the sociological points Pavel Kroupa raised. He even backs up the statement that it is difficult to go against the mainstrem by refering to one of his papers about very old stars, which was "brutally but superficially rejected". This is in-line with reports by other scientists who for example had observing proposals rejected because they suggested observing disk galaxies at a high redshift. Because the  time-allocation commission "knew" that these cannot have formed in a LCDM universe, the observing time was not granted.

On her Blog "One Small Step", Sarah Kendrew, a Post-Doc in Heidelberg, posts a good introduction to the background of the debate. She also mentiones that Pavel Kroupas main point was not to fighting for a particular alternative theory. She writes: "I get the impression that a large part of Kroupa’s argument is actually sociological: he’s calling for research into paradigm-challenging cosmologies like MOND to be given more attention (without smirking) and funding, rather than creating ever more patches to cover the holes in concordance cosmology." Concerning Simon Whites position, she makes an interesting statement: "White acknowledges the problems yet doesn’t think that a radical new line of thought is needed either [...]. Given his views on the future of astronomy [...] I would have thought he’d be all in favour of setting bright students’ creative minds loose on a problem like this."

As a last point, there was an email by a colleague. He shares some of his thoughts about the debate, which he attended himself. However, he asked us not to mention his name because he does not have a permanent position yet. He is afraid that articulating his point of view publicly will reduce his chances to ever get one. Of course we follow his request by citing him anonymously and would like to thank him for his trust in us which he showed by sending this email.

Simon White's statement that Pavel Kroupa is arguing with a "proof through assertion" is an insolence, as it supposes that the arguments lack any evidence. Consistently, in the following Simon White did not really adress the problems of Dark Matter. Instead, he showed where the standard model works. Ignoring criticism is bad scientific practice. In addition to this, Simon White tried to reduce Pavel Kroupa's arguments to a pro-MOND position, while the failures of the concordance cosmology have nothing to do with the question whether MOND is valid or not. While Simon White initially said that alternatives have to be investigated, he later argued that he gets a lot of letters each day proposing alternative cosmologies. This made Professor Klaas de Boer protest, as it puts theories like MOND on the same level as, for example, crackpot-ideas of non-academics claiming to have disprooven Einstein.

But there was also criticism concerning Pavel Kroupas presentation during the debate. His statement that he does not see any possibility to verify LCDM was perceived as a too fixed position. He might also have insisted more on discussing the small-scale problems of LCDM and that they can not simply be dismissed by stating that the physics at these scales is too complicated. This might have made the debate more ground-breaking, as a lot of people were hoping to see if there are proper counter-arguments to the findings presented in the recent paper. Furthermore, he could have reacted to Simon White's claim that Fornax fits excellently in LCDM, using the isophote-plots of the satellite galaxy he showed in his talk: If the galaxy were embedded in a dark matter halo, it could not be too asymmetric but would mostly be spherically and non-structured, which is not the case. During the debate, Pavel Kroupa did not raise this contradiction between Fornax and the LCDM model.

Another Debate (on TV)

This Thursday (November 25th 2010), at 9pm, there will be another discussion about dark matter in the TV show "scobel". It will be broadcasted on 3sat, a TV station in German providing a common program for Germany, Austria and Swizerland. The title is: "Dark Matter - New Studies Question its Existence". Guests in the show will be Arnold Benz, Gerhard Hensler and Simon White. A TV team of 3sat was filming at the Dark Matter Debate between Simon White and Pavel Kroupa last week, so this will probably be the first chance to see some footage of the event. Furthermore, Pavel Kroupa and Robert Sanders were interviewed for the show. Unfortunately, it is in German. It will be available online in the 3sat mediathek afterwards.

by Pavel Kroupa and Marcel Pawlowski (24.11.2010): "Reactions to the Dark Matter Debate and Another One in German TV" in "The Dark Matter Crisis - the rise and fall of a cosmological hypothesis" on SciLogs. See the overview of topics in  The Dark Matter Crisis.


4 Responses to “Reactions to the Dark Matter Debate and Another One in German TV”

  1. anand srivastava Reply | Permalink

    Interesting Paper on origin of Gravity

    I saw a couple of papers on the origination of gravity, via thermodynamics, Entropy and Holographic principle.

    There are several interesting papers based on the two, which derive MOND and Pioneer Anomaly. Basically the Newtonian force is only valid for geodesic motions in high gravitational potentials.

    Pardon my lack of knowledge. I am not a physicists. I have just been looking for something that comes along explaining MOND.

  2. Richard Moody Jr. Reply | Permalink

    MOND versus dark matter

    While MOND does give an excellent fit to gassy galaxies, computer modeling of the "walls and voids" gives you a good case for dark matter. It is tough to see with gravity alone how you can get the walls and voids forming in only 13.7 billion years.

    Here is a simple way to make them compatible. What if dark matter repels matter? This makes it a push rather than a pull.

    As the galaxies begin to form MOND takes over as dark matter is expelled. This could also explain why we don't see evidence of dark matter in our experiments.

    Finally dark matter would obviate the need for dark energy because it would give you walls, voids and an increase in the rate of universal expansion.

  3. Pavel Kroupa Reply | Permalink

    MOND vs Dark Matter by Richard Moody Jr

    The approach to add a new "dark" force which acts either between only the dark matter particles and/or between dark matter and normal matter has been tried. Example:
    Chuzhoy & Nusser:
    http://arxiv.org/abs/astro-ph/0408184
    Keselman, Nusser, Peebles:
    http://arxiv.org/abs/0912.4177

    While this sort of approach may appear to lessen some of the problems LCDM has, one would be adding unknown physics to solve problems which arise in the LCDM model which is already nearly exclusively based on unknown physics (inflation, dark matter and dark energy). That is, deviations between model and data is "solved" by adding more unknown parameters which are not accessible to direct experiment.

    That structures and voids do grow rapidly in a MONDian universe has been shown by e.g. Angus & Diaferio:
    http://arxiv.org/abs/1104.5040
    and also by
    Llinares, Knebe & Zhao:
    http://arxiv.org/abs/0809.2899

    These simulations are an admirable but only the first step. They are still unrealistic because the particles used in the calculations cannot be gas particles since the computer power is today not sufficient to treat the baryonic physics which dominates in a MONDian universe.

    A useful reveiw to read on this is
    "Modified Newtonian Dynamics: A Review"
    by Famaey & McGaugh
    ( http://arxiv.org/abs/1112.3960 )

    Overall, it seems that a MONDian universe looks surprisingly like the real thing out there.

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