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Discussing Gravity with Erik Verlinde

Posted 28 June 2012 by Marcel S. Pawlowski

We have just returned from a talk by the Bethe colloquium. Erik Verlinde from the university of Amsterdam spoke about “Dark Matter, Dark Energy and the Emergence of Gravity ”. Verlinde is a dutch theoretical physicist working on string theory and gravity. He became very famous for his theory of entropic gravity and was awarded the Spinoza Prize for his work. In his talk, he showed that his approach can not only reproduce the MONDian behavior of the different kinds... Read more

Does filamentary accretion of dark matter sub-halos naturally produce a VPOS-like structure?

Posted 15 May 2012 by Marcel S. Pawlowski

In the previous post we discussed the VPOS, the vast polar structure of satellite objects around the Milky Way. One of the suggested origins within the cosmological cold dark matter paradigm is that the satellites have been preferentially accreted along large, cosmic filaments. These are long, thread-like structures which arise naturally during the formation of structure in the cosmos. The movie below shows how they come about: One work suggesting that filamentary accretion can solve the VPOS-problem is Lovell et... Read more

The vast polar structure – VPOS – of satellite objects around the Milky Way

Posted 28 April 2012 by Marcel S. Pawlowski

After the worrisome news for dark matter in the last weeks, we have to add another today, based on our research (and there is more to come very soon). We show that the disc of satellite galaxies is only a part of a bigger structure: a vast polar structure (VPOS) of diverse satellite objects surrounds the Milky Way, unexpected from cosmological models. The work was done at the University of Bonn, largely through the support of the German Research Foundation... Read more

Dark Matter gone missing in many places: a crisis of modern physics?

Posted 19 April 2012 by Marcel S. Pawlowski

On The Dark Matter Crisis, we have already presented numerous problems that appear within the LCDM model of cosmology. Some of these have been given names, like the “Missing Satellites Problem”, where LCDM predicts more dark matter subhaloes around the Milky Way than there are observed satellite galaxies, which are expected to trace them. Or the “Missing Baryons Problem”: from cosmological predictions we expect a certain density in the baryonic, luminous and thus in principle observable matter. But when you... Read more

German TV tip: physics at the verge of collapse – science in the dark

Posted 17 April 2012 by Marcel S. Pawlowski

A short TV-tip for our German readers: on April 17 (today) at 18:30 on 3sat there will be a "nano spezial" about fundamental problems of physics and cosmology, dark matter and dark energy. It is titled "Physik vor dem Kollaps - Die Wissenschaft steht im Dunkeln". It includes an interview with Pavel Kroupa. For those without TV: the programme can already be found online in the 3sat Mediathek and will be available for the next seven days. ... Read more

Question D: What about the Bullet cluster? And what about the Train-Wreck cluster Abell 520?

Posted 15 April 2012 by Pavel Kroupa

Summary: One result is very definite by now: neither the Bullet nor the Train Wreck clusters support (nor do they prove) the existence of cold or warm dark matter. And, they certainly do not disprove MOND. Quite on the contrary, according to current knowledge, they falsify the concordance cosmological (or LCDM) model. The Bullet cluster consists of two clusters of galaxies that have penetrated each other leaving behind a slab of gas while the now seperating clusters retain matter as... Read more

Question C.III: Fundamental theoretical problems

Posted 31 March 2012 by Pavel Kroupa

Rather than being posted "soon after" II: MOND works far too well ! (published on the 21.03.2011), a delay caused by internal university issues arose. We are back though, for the time being, with the originally advertised "Question C.III: Fundamental theoretical problems" (this contribution). To re-iterate: what is the purpose of this series on SciLogs? We are aiming to document, within the time we have for such matters, the already noticeable paradigm shift away from a dark-matter dominated Einsteinian inflationary... Read more

Question C.II: MOND works far too well !

Posted 21 March 2011 by Pavel Kroupa

Summary: First try: Using only Solar System constraints, Newton and then Einstein developed the universal theory of gravitation. This Theory of General Relativity (GR) is then applied to model the universe. In order for it to fit the observational cosmological constraints, inflation, dark matter and dark energy need to be postulated to exist. Tests on scales of 10Mpc and less show this top-down modelling to fail despite major fine-tuning attempts.  Second try: Using Solar System and galactic constraints Milgrom and... Read more

Question C.I: What are the three best reasons for the failure of the LCDM model? I: Incompatibility with observations

Posted 8 March 2011 by Pavel Kroupa

Summary: The development of the concordance cosmological model (CCM) over the past 40 years is based on the addition of at least three unknown ("dark") physical phenomena (inflation, cold dark matter, dark energy), in an attempt to make Einstein's field equation account for the distribution of matter on galactic and larger scales. None of these are understood nor experimentaly verified today. While these may constitute true discoveries of new physics, much as in the spirit of the past when for example... Read more

Question B2: What is a galaxy? (Addendum on the relaxation time)

Posted 23 January 2011 by Pavel Kroupa

Background: As introduced in the previous contribution to The Dark Matter Crisis, Question A: Galaxies do not work in LCDM, sociology and majority views, PK was recently contacted by a few people, and here are excerpts from some of the questions asked and the replies. These help to illustrate some of the issues at hand. The questions are A) So the LCDM model fails on scales smaller than about 8 Mpc? B1) What is a galaxy? B2) What is a galaxy?... Read more