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Previous Next Up Topic Cosmology / Alternative Cosmology / Dark Matter? No, It's a New Woo-Woo Force! (6852 hits)
By Mike Petersen Date 2009-10-05 19:29
Unsatisfied with the idea that Dark Matter may not exist at all (gasp!), a new study suggests - well, read it for yourself:

Galaxy study hints at cracks in dark matter theories

On the other hand, I'm glad to see that they at least make passing mention of MOND.

Comments?

- Mike Petersen
By Jade Annand Date 2009-10-06 04:57 Edited 2009-10-06 04:59
Comments?


Inevitable :)

Is this force different than the mystery forces being posited last month(?) ?

Apart from that, the observations we're getting are pointing to something pretty strange but with tractable relationships, even if it takes a while to suss them out. Most alternative cosmologies spend a lot of time on many things, but generally pay little attention to things like rotation curves, MOND/TeVeS excepted, though they are certainly incomplete as cosmologies in and of themselves.

I do wonder why galaxies rotate the way they do.

The comment sections, not just in that article, but in many other places on the same topic, are hilarious free-for-alls :)
By Mike Petersen Date 2009-10-11 13:17
Now, how could we all have missed this three years ago?  Does anyone have any idea if this team has followed up on their paper?

Dark Energy and Dark Matter – The Results of Flawed Physics?

Regards,
Mike Petersen
By Jade Annand Date 2009-10-21 07:08
Hmmm, the paper being referred to is this one (preprint here). Capozziello is pretty prolific and refers quite a bit to dark matter, dark energy (in particular) and alternate theories of gravity in general.

As far as follow-up, I'm not sure. A number of the papers seem to refer to the topic tangentially. One of his own that cites that paper (there seem to be quite a lot of other cites for that paper) is f(R) cosmology with torsion.

I'm intrigued at the way they do not mince words:

ΛCDM has recently assumed the role of a new Cosmological Standard Model giving a coherent picture of the today observed universe [1]. Although being the best fit to a wide range of data, it suffers of several theoretical shortcomings [2] so it fails in tracking cosmic dynamics at every redshift and fails in according observational cosmology to some fundamental theory of
physical interactions. Among the defects of this model, there is the lack of final probes, at fundamental level, for dark energy and dark matter candidates (which should be the 95% of the energy-matter content of the universe!) which frustrates the possibility to reduce ΛCDM to some self-consistent scheme, despite of the fact that it is a fair ”snapshot” of the present status of the universe. These facts motivate the search for other models, among which alternative theories of gravity that should reproduce the successes of ΛCDM but should be more appropriate in describing the cosmological dynamics [3, 4].

In particular, the large part of dark energy models relies on the implicit assumption that Einstein’s General Relativity (GR) is the correct theory of gravity indeed. Nevertheless, its validity on large astrophysical and cosmological scales has never been tested but only assumed [5], and it is therefore conceivable that both cosmic speed up and missing matter, respectively the dark energy and the dark matter, are nothing else but signals of a breakdown of GR at large scales.


I'm intrigued at folks positing the breakdown of GR at larger scales.
By Ari Jokimäki Date 2009-11-11 09:12
There's another paper out on dark matter (I haven't followed the issue much myself but saw this in arXiv):

New evidence for dark matter - Boyarsky et al. (2009).

Abstract:
"We present a new universal relation, satisfied by matter distributions at all observed scales, and show its amazingly good and detailed agreement with the predictions of the most up-to-date pure dark matter simulations of structure formation in the Universe. This work extends the previous analysis [0904.4054; 0909.5203] to a larger range of masses, demonstrates a different scaling law, and compares it with numerical simulations. This behaviour seems to be insensitive to the complicated feedback of baryons on dark matter. Therefore, it potentially allows to compare theoretical predictions directly with observations, thus providing a new tool to constrain the properties of dark matter. Such a universal property, observed in structures of all sizes (from dwarf spheroidal galaxies to galaxy clusters), is difficult to explain without dark matter, thus providing new evidence for its existence."
By Ari Jokimäki Date 2010-03-25 07:48
Hi Azelx7, and welcome to the forum! :)

Azelx7 said:

...what are some supposed cosmological alternatives to dark energy and dark matter?


Well, Halton Arp at least has argued that his intrinsic redshift hypothesis gets rid of dark matter but I haven't seen him commenting on the situation with a single galaxy, I think his arguments have been on galaxy groups and clusters. For dark energy Arp & Narlikar (1997) have proposed that variable mass hypothesis (which is static model without dark energy) survives the issue of time dilation in supernovae which I think is the main body of evidence for the dark energy.
By Mike Petersen Date 2010-03-26 00:30
Azelx7,

Very good points.  Perhaps you might want to investigate string theory and what it has to say about the cosmological constant.  The additional dimensions of the theory seem to cover the "smoothing" of the quantum foam to make its value more in line with a flat universe.  The idea is that the frenetic activity of the "Planck-length" foam is actually taking place in one or more of the seven(!) additional dimensions of 11-dimensional string theory.  I might recommend some of the less mathematically rigorous writing explaining string theory in the book by Brian Greene, "The Elegant Universe."

Regards,
Mike Petersen
By Ari Jokimäki Date 2010-03-27 06:15
Azelx7 said:

According to CMB measurements, dark matter/baryonic matter only make up 30 percent of the critical density. So dark energy supposedly makes up the other 70 percent for a flat, homogeneous, isotropic universe; and isn't there evidence that dark energy is found in supervoids and superclusters? What does the VMH say about this?


I'm not sure what it specifically says about it, but one thing you need to realise is that in VMH universe is infinitely old and space is flat and non-expanding, so not everything that is discussed in the context of Big Bang cosmology applies to VMH. I don't remember exactly what Arp suggests CMBR is, but I think it some sort of product of combined distant starlight. I have seen Arp suggesting that voids are not real but are the result of intrinsic redshift. Here is one example of Arp explaining how some illusions arise to the large scale structure:

http://www.haltonarp.com/articles/fingers_of_god_in_an_expanding_universe
Previous Next Up Topic Cosmology / Alternative Cosmology / Dark Matter? No, It's a New Woo-Woo Force! (6852 hits)

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