Re: MOND
- From: "Juan R." <juanrgonzaleza@xxxxxxxxxxxxxxxxxxxx>
- Date: 10 Mar 2007 10:28:52 -0800
On Mar 1, 5:25 am, "Eric Gisse" <jowr...@xxxxxxxxx> wrote [in reply to
anands...@xxxxxxxxx]:
MOND is nonrelativistic curve fitting
No, MOND is a law. The GR+DM models are pure “curve fitting”.
that abjectly fails in the case
of the bullet cluster.
[i] MOND community has replied to that.
[ii] GR fails to deal with the bullet cluster even after introducing
the DM assumption. Now new hypotesis are invoked. The Frenk principle
I cited in a previous post is adequate for the DM paradigm invented by
relativists.
[FRENK PRINCIPLE
If the Cold Dark Matter Model does not agree with
observations, there must be physical processes,
no matter how bizarre or unlikely, that can explain
the discrepancy.
]
With the bullet cluster, one would introduce the
[STRONG FRENK PRINCIPLE
The physical processes must be the most
bizarre and unlikely...
]
[iii] Conclusion: GR does not work fine for the bullet cluster and
galaxies.
It never had a chance at being useful from the
beginning since it couldn't handle relativistic effects.
Your n-th emphasis on raw MOND lacking relativistic effects is again
pure nonsense because at least three motives:
[i] Relativistic effects are small for dynamics at the galactic scale.
MOND signifies MOdified Newtonian Dynamics.
[ii] MOND fits observational data on galaxies with a precision GR+DM
cannot achieve. Using 300% or more parameters than MOND models does
not help to GR.
[iii] There exists something called relativistic MOND. You were said
about this three or four times and by more than an author.
If a equation (MOND) can fit all galaxies with a single
universal parameters then it has some truth in it.
MOND can't. If you think it can, back up the assertion with some
halfway decent references.
The _inverse_ of your claim is fine. It is well established that GR
cannot fit data at galactic scale so well as MOND. The precision of
MOND rocks over the weak GR+DM model.
Since GR+DM cannot offer MOND quality, it is very funny to see
relativists trying to convince to astronomers that the quality offered
by GR is “close enough!”.
[BLOCKQUOTE
If we are convinced that CDM is correct, it is easy to
look at this and say "close enough!" but the sad fact is
that CDM is still very far from making predictions that are
either as rigorous or as successful as MOND on galaxy scales.
]
It is interesting that you ask him for references but you provide none
for your creed “MOND can't” apart from an unrelated and ‘biased’ paper
on cosmology and WMAP.
If you think DM is bunk, explain why the lambda-CDM [cold dark matter]
model fits the WMAP 1st and 3rd year data runs so well, as well as
being independently confirmed by the Sloan digital sky survey data.
Several precisions and corrections may be done:
[i] The Λ-CDM model only fits well the region prior to 800 in the WMAP
spectrum. The ‘third peak’ is not fitted neither by lambda-CDM nor by
the non-CDM model.
[ii] Λ-CDM did very wrong on the past. E.g. the 1999 year fitting
being discredited by MOND community. Yes, that part of history is
forgotten in GR propaganda...
[iii] The Λ-CDM model uses 6 parameters; the non-CDM model uses 3.
However, the fit of the Λ-CDM model is not six times better than for
the latter model. Moreover the non-CDM model is an approximated model
to a precise MOND cosmology model.
[iv] The lambda-CDM model fits the whole WMAP spectrum _a posteriori_
i.e. pure curve fitting. The non-CDM model ***predicted*** the correct
first and second peaks. See point [ii].
[v] The non-CDM model used was non-relativistic. It has been stated
that relativistic MOND models can fit the whole WMAP spectrum.
Remember [i] and [iii].
[vi] The lambda-CDM model fits WMAP data by forcing a barionic density
is not very compatible with results obtained from independent tests.
The non-CDM model is more in concordance with other tests of that
parameter.
[vii] The DM model continues working bad at both galactic and cluster
scales.
Also to make matters worse for DM no theory works simultaneously
on LSB galaxies and giant Elliptical galaxies.
If you say so.
MONDS works fine, fits better than GR+DM and has done innumerable
verified predictions. See references already cited.
Duh. We don't know what dark matter is or how it interacts with
itself, or anything else.
Some remarks:
[i] Above you are asuming that DM exists in nature, but reality is we
do not know if DM really exists or is only an artifact invented by
relativists.
[ii] Your dogmatic style of posting lets you to introduce any kind of
excuse on the GR side whereas tolerating none for the MOND paradigm.
Why?
People
whine that dark matter is a 'kludge' and then, inexplicably, turn to
theories like MOND or TeVes which are even more of a kludge.
It may look inexplicable for you but the rationale for astronomers and
physicists to abandon GR and dark matter is as follows.
They want fit experimental data with precision (GR+DM cannot do it).
They want a predictive law (GR+DM is not predictive) and each time a
new MOND prediction is verified by subsequent observation they do a
party.
They are tired out of hypotesis, contradictions, and _ad hoc_
procedures about an elusive new form of matter nobody has observed or
understand.
Nobody knows what dark matter is.
Again incorrect scientific approach! Nobody knows if dark matter
really exists.
http://en.wikipedia.org/wiki/Lambda-CDM_model
It is a model of the universe that makes a very good fit with 6
numbers. Think about that for a minute.
[i] That model already did wrong fittings in the past, e.g. the 1999
year fit. No warranties. “Think about that for a minute”.
[ii] That model is using 6 parameters and is unable to fit the whole
WMAP (BOOMERANG) region yet. “Think about that for a minute”
[iii] The non-CDM model, using 3 parameters, fits the first and second
peaks with the same precision than Λ-CDM (needing six). “Think about
that for a minute” or two.
[iv] The Λ-CDM model is _a posteriori_ curve fitting:. MOND community
***predicted*** the correct both first and second peaks before the
data were available. “Think about that for a minute”.
[v] There are doubts about the values for the Λ-CDM parameters used in
the WMAP fit. For instance, independent tests for Ω_b are more
compatible with non-CDM model that with the Λ-CDM assumed value.
“Think about that for a minute”.
L-CDM is a *model* with specific falsifiable assumptions about what is
being modeled. MOND is a "dunno. fit it to a curve" theory.
It is just the inverse. The Λ-CDM is pure fitting _a posteriori_.
MOND people, ***predicted*** both the first and second WMAP peaks.
Previous Λ-CDM models were completely wrong about WMAP would record.
Now that fiasco is forgotten. Why?
The original incarnation of MOND
is dead and buried,
Do not true, MOND is actively being used by astronomers because rocks.
From a recent conference on the topic:
[BLOCKQUOTE [1]
This systematic, more than anything else, tells us
we might be facing a failure of the law of gravity
in the weak field limit rather than the effects of
dark matter. [...] Despite many attempts, MOND
resisted stubbornly to be falsified as an alternative
to dark matter and succeeds in explaining the
properties of an impressively large number of objects
without invoking the presence of non-baryonic dark
matter. This suggests MOND is telling us something
important about gravity in the weak field limit.
]
Bullet cluster, bullet cluster, bullet cluster. Until the anti-dark
matter crowd adequately explains the bullet cluster, dark matter has a
serious point in its' favor.
[i] GR is not compatible with the bullet cluster data. Not even adding
unobserved DM, GR is really working. Now the creed is that a new kind
of mysterious attraction has to be adittionally invoked. What will be
the next? Pink elephants at Planck scale?
[ii] There are several plausible explanations for the bullet cluster
becoming from MOND community.
[iii] The GR+DM model continues without working fine at galactic
scale.
The anti-DM crowd also needs to explain
why the L-CDM model does such an excellent job.
Excellent job? Cof, cof, cof, the Λ-CDM model is not really convincing
astronomers.
[BLOCKQUOTE [Stacy McGaugh]
Current cosmology (ΛCDM) invokes not one but two aethers
(dark matter and dark energy); let us be careful not to
fall into the same conceptual trap that led classical
physicists to infer that Maxwell’s theory required aether.
]
As well as why the
dark matter assumed by the L-CDM model [cold non-interacting _non-
baryonic_ dust] is such a good model for something that they claim is
an artifact of gravitation.
Good model?
There is a recent work now in press (2007 ApJ) by McGaugh; de Blok,
Schombert, de Naray, Kim where data from 60 galaxies are compared to
structure formation simulations in a Λ-CDM framework. In short, Λ-CDM
fails. To be noticed MOND rocks for the same 60 galaxies providing the
most fine prediction (Q = 1).
Can you name one interaction effect that gets stronger as distance
increases? No, please don't argue that gravity is like a harmonic
oscillator.
In MOND, interactions are weaker as distance increases.
GR is highly accepted by PHYSICISTS [relativists is a crank term used
by those who wish to dilute the language in order to make their
position appear more valid]
Earlier I cited for you Weinberg (the Nobel) and Hillman (Baez site)
using the term “relativist”. I also offered for you a definition of
relativist (extracted from dictionary) as physicist specialized in
relativity theory.
Your ‘persecution’ and ‘conspiracy’ theories are especially hilarious.
because of the extreme validity of the
predictions it makes.
Exact! That is why GR has got serious problems at galactic scale.
Either does not predictions or clearly disagree with observational
data.
I disagree with the assertion that MOND works everywhere. It most
certainly fails to take into account any relativistic effects,
Wow! a ***non-relativistic*** theory failing to account any
relativistic effects. That may be the end for the humanity.
Your crazy attack to MOND is so predictible that was addressed in a
number of works. For instance, Sanders wrote
[BLOCKQUOTE
Frequently, the absence of a covariant theory is presented
as an argument against MOND. But the criterion for judging
a scientific hypothesis surely must be its empirical success.
The absence of a successful covariant version is simply an
aspect of its incompleteness. People don’t reject general
relativity because there is not yet a viable theory of
quantum gravity.
]
Yes, you (and dogmatics relativists) confound incomplete with wrong,
but who care?
and I
am yet to see evidence for the assertion that it predicts the way
galaxies rotate correctly. I expect that it is a different scaling
parameter for each galaxy.
Cof, cof, cof!
MOND doesn't work on the small scale [planets, star systems, star
clusters] and it doesn't work on the large scale [superclusters,
clusters].
MOND works fine and has done predictions. For example predicted the
correct high for the second peak on WMAP when Λ-CDM did not predicted.
MOND also works for apples on Earth, and last time I studied this
theme Earth was a planet, is not more?
It only works on galaxies, and even that is debatable.
[BLOCKQUOTE
the sad fact is that CDM is still very far from
making predictions that are either as rigorous
or as successful as MOND on galaxy scales.
]
Even then, a theory that is broken from the beginning somehow proves
GR wrong!
[i] MOND is not a broken theory. MOND is a law and very satisfactory
one.
[ii] MOND has done multiple predictions during last two decades. All
predictions were confirmed by observation. GR people has done none of
those predictions and often pointed in the wrong way: 1999 Λ-CDM, LSB,
and others.
[iii] GR does not work at galactic scale. Add DM and will continue
without working.
Even though observation is entirely consistent with dark
matter being real actual matter that doesn't electromagnetically
interact.
“observation is entirely consistent”... Pure Gisse’s advertisement
again. The DM model does not work: fine tuning problem at galactic
scale, the problems at cosmological scale, the recent fiasco at bullet
cluster...
[1] http://scitation.aip.org/getabs/servlet/GetabsServlet?prog=normal&id=APCPCS000822000001000253000001&idtype=cvips&gifs=yes
.
- References:
- MOND
- From: Juan R.
- MOND
- Prev by Date: MOND
- Next by Date: Re: MOND
- Previous by thread: MOND
- Next by thread: Re: MOND
- Index(es):
Relevant Pages
|
Loading
