Re: MOND
- From: "Juan R." <juanrgonzaleza@xxxxxxxxxxxxxxxxxxxx>
- Date: 10 Mar 2007 10:30:27 -0800
On Mar 1, 10:43 am, "Eric Gisse" <jowr...@xxxxxxxxx> wrote [in reply
to anands...@xxxxxxxxx]:
Just keep in mind that lamba-CDM isn't supposed to be a model for
smaller scale objects.
[i] However, the Λ-CDM cosmological model introduces bounds for
smaller scale objects. A recent review of data for 60 galaxies (in
press) reflects Λ-CDM bounds are not fine.
[ii] The Λ-CDM model presents problems for fitting WMAP data.
120 galaxies with the same scaling parameter? Interesting, but
unsupported. Please stop asserting things you know I will have a hard
time taking a face value without some kind of support.
Please check literature before posting nonsense.
[BLOCKQUOTE
Dark matter may address the general trends but it cannot
account for the individual idiosyncrasies of each rotation
curve. In the next section we present the evidence that
MOND can do this with a single value of a_0.
]
Astronomers have filled entire catalogs with hundreds of galaxies of
different classes and ranges where predictions of MOND are completely
supported by data, even in fine-tuning. Whereas, GR continues to fail,
even with _a posteriori_ DM curve fiting using tree or more parameters
models.
I know of no DM theory that explains individual galaxies. My
understanding is that the basic DM theory is that there is enough dark
matter inserted to preserve the expected rotations.
No, the DM theory is not working at galactic scale.
[BLOCKQUOTE
The success of detailed rotation curve fits
is highly non-trivial. Once the form of the
force law is specified, the dynamics must
follow from the observed baryon distribution.
This procedure is much, much, much more
strongly constrained than fits with an invisible
dark matter component, which can be arranged
however needed. Such fits have a minimum of
three free parameters, resulting in enormous
freedom and numerous degeneracies. [...]
On the scale of individual galaxies,
MOND clearly performs better than CDM.
]
Keep in mind that we don't know how DM works on a galactic level. We
don't know what it is made of.
Correction: we do not know if DM is real or is only and artifact being
invented by relativists.
It doesn't fail if dark matter is assumed. Which is the _entire point_
of dark matter.
That is not true, apart from not fitting data with MOND quality, GR+DM
has conceptual problems and internal inconsistencies. For instance,
neither GR nor DM cannot explain the well-established TF law.
MOND community ***predicted*** the TF law before was observed and
broadly used by astronomers.
dark matter is assumed to pick up the slack. It is a
model that works on supercluster scales [WMAP data and such], is
supported by individual galaxies by default, and is supported by other
observations.
DM is not fine at galactic scale: fine-tuning problem.
DM fails to pass all galactic test at once: the consistency problem.
DM fails on clusters and superclusters (needed additional _ad hoc_
hypotesis for bullet cluster).
DM is not able to fix ‘third peak’ on WMAP and the fit to first and
second peaks is forced by assuming discusible values for some of the
six parameters.
DM is not predictive but pure curve fitting ‘art’.
DM is not supported by any theory of particle physics.
DM has been never found in despite of many efforts to observe it.
If I ignore whatever MOND does at galactic scales,
it fails at everything else to one degree or another.
MOND is satisfactory for data and predictions and used by astronomers.
DM is not observed, has no theoretical rationale on particle physics,
and empirically fails at to one degree or another.
[BLOCKQUOTE
It is in this second aspect, the distribution of
dark matter in galactic systems, that the
CDM paradigm encounters observational difficulties
]
[BLOCKQUOTE
This algorithm is arguably more successful in explaining
aspects of galaxy phenomenology than is dark matter in
the context of the CDM paradigm
]
[BLOCKQUOTE
At the same time, the inferred contribution of CDM to the
mass budget of the Universe has dropped from 95% to perhaps
30%, and both observational and theoretical problems have
arisen with the predicted form of halos
(Sellwood & Kosowsky 2001). However, all of this has not
deterred imaginative theorists from speculative extrapolations
of the standard model to conjure particles having the properties
desired to solve perceived problems with dark matter halos.
It is surely time to apply Occam’s sharp razor and seriously
consider the suggestion that Newtonian dynamics may breakdown
in the heretofore unobserved regime of low accelerations.
]
.
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