Re: MOND
Eric Gisse
wrote:
[...]
It is unfortunate you spent so much time writing something I will not
take the time to read or reply to. Stop pretending I care what you
think.
anan...@gmail.com
wrote:
> On Mar 1, 5:25 am, "Eric Gisse" <jowr...@gmail.com> wrote [in reply to
> anands...@gmail.com]:
> > Can you name one interaction effect that gets stronger as distance
> > increases? No, please don't argue that gravity is like a harmonic
> > oscillator.
>
> InMOND, interactions are weaker as distance increases.
>
Actually force between Quarks increases with distance.
That's why they don't exist alone.
Well the thing is AdS/CFTs behave very counter-intuitively.
And gravity should be an AdS/CFT theory, just like the other
three forces.
So we don't know if the actual interaction will increase
with distance. MOND doesn't.
regards,
-anandsr
Shubee
wrote:
>
> Eric Gisse ignorance is legendary and well-known in this newsgroup.
Eric Gisse is a chimpanzee. I for one appreciated your defense of
MOND.
Shubee
Eric Gisse
wrote:
> On Mar 17, 5:35 am, anands...@gmail.com wrote:
>
> > On Mar 10, 11:28 pm, "Juan R." <juanrgonzal...@canonicalscience.com>
> > wrote:
>
> > > On Mar 1, 5:25 am, "Eric Gisse" <jowr...@gmail.com> wrote [in reply to
> > > anands...@gmail.com]:
> > > > Can you name one interaction effect that gets stronger as distance
> > > > increases? No, please don't argue that gravity is like a harmonic
> > > > oscillator.
>
> > > InMOND, interactions are weaker as distance increases.
>
> > Actually force between Quarks increases with distance.
> > That's why they don't exist alone.
>
>
> [i] It was a bit off-topic.
>
> [ii] My personal experience replying Eric Gisse posts recommended
> avoiding advanced topics. I doubt he has studied QCD.
Of course I haven't, and neither have you. Unless you can suddenly
demonstrate a superb grasp of quantum mechanics, that is.
It would also be really odd to cite observation of quark confinement
when the conversation was clearly about macroscopic objects since the
strong force doesn't even exist outside the nucleus, much less on
Hubble length scales.
>
> Eric Gisse ignorance is legendary and well-known in this newsgroup. I
> could also try to explain him that GR introduces interactions got more
> stronger for large distances [1] and therefore his childish criticism
> against MOND also aplies to GR. But i decided that a more simple and
> direct reply would be more adequate.
I was unaware of the Schwarzschild-de Sitter solution.
http://arxiv.org/PS_cache/gr-qc/pdf/0602/0602002.pdf
That was a fun read.
>
> For large accellerations MOND is [1 / r^2].
>
> For small accellerations MOND is [1 / r].
>
> Therefore in MOND, interactions are weaker as distance increases. I do
> not know from where Eric Gisse got the wrong idea that MOND is like an
> oscillator.
Me neither, because I never said that.
>
> > Well the thing is AdS/CFTs behave very counter-intuitively.
> > And gravity should be an AdS/CFT theory, just like the other
> > three forces.
>
> > So we don't know if the actual interaction will increase
> > with distance. MOND doesn't.
>
> > regards,
> > -anandsr
>
> [1] Schwarszhild solution for Hilbert-Einstein equations without
> cosmological constant PHI = [2GM / r] receives a r^2 contribution when
> LAMBDA re-introduced:
>
> PHI = [2GM / r] - [ [LAMDA / 3] * r^2] contribution.
Eric Gisse
Poor little shooby is upset because he doesn't have any answers for my
constant questions like "why should anyone care?" or "what are your
axioms?".
>
> Shubee
anan...@gmail.com
wrote:
> > wrote:
>
> > > On Mar 1, 5:25 am, "Eric Gisse" <jowr...@gmail.com> wrote [in reply to
> > > anands...@gmail.com]:
> > > > Can you name one interaction effect that gets stronger as distance
> > > > increases? No, please don't argue that gravity is like a harmonic
> > > > oscillator.
>
> > > InMOND, interactions are weaker as distance increases.
>
> > Actually force between Quarks increases with distance.
> > That's why they don't exist alone.
>
>
> [i] It was a bit off-topic.
It is not off-topic, if the question was "is there an interaction
which increases with distance", because there is an interaction.
It doesn't matter if it is microscopic or macroscopic. After all
microscopic does affect the macro world. And we know that the
microscopic makes up the world.
>
> [ii] My personal experience replying Eric Gisse posts recommended
> avoiding advanced topics. I doubt he has studied QCD.
I wouldn't know about that. But when we are talking about the failures
of GR, then Quantum Theory definitely comes into the picture because
it is GR's biggest failure. Some may say that it is QCD's failure but
I doubt many will see it that way. It is definite that GR will be
found in the limit of a Quantum Theory of Gravity, rather than
QCD to be found in the limit of GR ;-).
So we start with the statement that GR is true in a limit of a
Quantum Theory of Gravity, which means that GR is not the true
picture. So I don't know why Relativists find it so difficult to
come to terms with the fact that MOND works and proves that the
Limit of GR is a few kilo parsecs. Although Pioneer may mean that
something is wrong there too. But Pioneer seems to be a fluke
rather than an indication of something wrong.
regards,
-anandsr
Eric Gisse
> On Mar 17, 9:05 pm, "Juan R." <juanrgonzal...@canonicalscience.com>
> wrote:
>
>
>
> > On Mar 17, 5:35 am, anands...@gmail.com wrote:
>
> > > On Mar 10, 11:28 pm, "Juan R." <juanrgonzal...@canonicalscience.com>
> > > wrote:
>
> > > > anands...@gmail.com]:
> > > > > Can you name one interaction effect that gets stronger as distance
> > > > > increases? No, please don't argue that gravity is like a harmonic
> > > > > oscillator.
>
> > > > InMOND, interactions are weaker as distance increases.
>
> > > Actually force between Quarks increases with distance.
> > > That's why they don't exist alone.
>
> > True, that is quarks confinement. But i did not cited because:
>
> > [i] It was a bit off-topic.
>
> It is not off-topic, if the question was "is there an interaction
> which increases with distance", because there is an interaction.
> It doesn't matter if it is microscopic or macroscopic. After all
> microscopic does affect the macro world. And we know that the
> microscopic makes up the world.
I should have been more clear. I knew about quark confinement, I just
expected a shade more thought to be given to the subject than was
actually given.
"microscopic" is still a half dozen orders of magnitude too large for
the strong force interactions. Strong force interactions are of the
femtometer range - and DO NOT EXIST outside it because the strong
force mediating particle [whatever the fuck it is] is massive.
What I *meant* was name one verified macroscopic interaction which
_increases_ with distance with emphasis on both _verified_ and
_macroscopic_.
>
>
>
> > [ii] My personal experience replying EricGisseposts recommended
> > avoiding advanced topics. I doubt he has studied QCD.
>
> I wouldn't know about that. But when we are talking about the failures
> of GR, then Quantum Theory definitely comes into the picture because
> it is GR's biggest failure. Some may say that it is QCD's failure but
> I doubt many will see it that way. It is definite that GR will be
> found in the limit of a Quantum Theory of Gravity, rather than
> QCD to be found in the limit of GR ;-).
I think it is premature to worry about GR being the limiting case of
anything because we haven't truly found it to be failing. I know your
position on dark matter and you know mine. That aside, it must break
down _somewhere_ but we haven't actually seen it happen yet.
>
> So we start with the statement that GR is true in a limit of a
> Quantum Theory of Gravity, which means that GR is not the true
> picture. So I don't know why Relativists find it so difficult to
> come to terms with the fact that MOND works and proves that the
> Limit of GR is a few kilo parsecs. Although Pioneer may mean that
> something is wrong there too. But Pioneer seems to be a fluke
> rather than an indication of something wrong.
My money is on outgassing and/or asymmetric RTG heat reflection.
MOND working, for suitable definitions of working, does not prove
anything other than MOND is a halfway decent model under certain
conditions.
>
> regards,
> -anandsr
anan...@gmail.com
> On Mar 19, 12:56 am, anands...@gmail.com wrote:
>
>
>
> > On Mar 17, 9:05 pm, "Juan R." <juanrgonzal...@canonicalscience.com>
> > wrote:
>
> > > On Mar 17, 5:35 am, anands...@gmail.com wrote:
>
> > > > On Mar 10, 11:28 pm, "Juan R." <juanrgonzal...@canonicalscience.com>
> > > > wrote:
>
> > It is not off-topic, if the question was "is there an interaction
> > which increases with distance", because there is an interaction.
> > It doesn't matter if it is microscopic or macroscopic. After all
> > microscopic does affect the macro world. And we know that the
> > microscopic makes up the world.
>
> I should have been more clear. I knew about quark confinement, I just
> expected a shade more thought to be given to the subject than was
> actually given.
>
> "microscopic" is still a half dozen orders of magnitude too large for
> the strong force interactions. Strong force interactions are of the
> femtometer range - and DO NOT EXIST outside it because the strong
> force mediating particle [whatever the fuck it is] is massive.
>
> What I *meant* was name one verified macroscopic interaction which
> _increases_ with distance with emphasis on both _verified_ and
> _macroscopic_.
>
But when there are only four known interactions, if even one of them
increases with distance, why would you want to neglect that.
Also QED (the Electro Magnetic interaction) also has a weird
interaction, called entanglement that does weird things even at a
huge distance, and instantly without coming into conflict with
superluminal expectations. I guess that is very macroscopic, and
it very much conflicts with GR. But you can chose to ignore that,
saying that some GR expectations like causality are not broken.
I know that you actually mean only the gravitational interaction,
but in my opinion GR is already broken. I think the accelerated
expansion of the universe is due to repulsive force of gravitation,
and that will have to occur only if it increases with gravity. Its
all speculation, but you know that we don't have the quantum theory
of gravity.
>
>
> > > [ii] My personal experience replying EricGisseposts recommended
> > > avoiding advanced topics. I doubt he has studied QCD.
>
> > I wouldn't know about that. But when we are talking about the failures
> > of GR, then Quantum Theory definitely comes into the picture because
> > it is GR's biggest failure. Some may say that it is QCD's failure but
> > I doubt many will see it that way. It is definite that GR will be
> > found in the limit of a Quantum Theory of Gravity, rather than
> > QCD to be found in the limit of GR ;-).
>
> I think it is premature to worry about GR being the limiting case of
> anything because we haven't truly found it to be failing. I know your
> position on dark matter and you know mine. That aside, it must break
> down _somewhere_ but we haven't actually seen it happen yet.
>
GR has broken down and miserably. But you are turning a blind eye
to it. MOND is the indicator. You chose to ignore MOND because you
cannot explain it. If you could you would have done so. But it is a
fact that GR+DM cannot explain MOND LAW. It is not possible to
explain such a tight correlation between the Mass Discrepancies and
the observed accelerations. If you have a theory you can do so.
Nobody has done that till now. And nobody who has measured the
closeness of the correlation will believe that it can be done.
You will again say that I am ignoring weak lensing. But I will say
what's so different about weak lensing, it also shows Mass
Discrepancy which is also an indication that GR has broken down, we
are again seeing Mass Discrepancies. Then you will say WMAP, again
the same Mass Discrepancy. Of course all these mean that there is
something wrong with GR, but you think that you are seeing different
confirmation of Dark Matter while the reason for all the
Mass Discrepancy, is the same. GR does not work in weak gravity
regimes.
To you it doesn't matter that the Mass Discrepancy is increasing
with the scale. At the Galaxy level it depends on the size and
density (basically the weakness of gravity), at the cluster level
it is 10 times. At the Cosmic level it is 100 times. But you will
see all these similar failings as confirmation of Dark Matter.
You will also ignore the only thing that can open your mind.
Because it is so much more easy to live with the status quo.
You don't want to face the possibility that we don't know any
theory that can account for weak gravity regimes. This is
actually a great time for theoretical physicists to try and
find the correct theory, and quite a few are working towards
them, and I am not talking about crackpots. Search for papers
on TeVeS, Conformal Loop Quantum Gravity, AdS/CFT gravity.
But it is a difficult thing to do, you have to be great at
mathematics. These theories are much more difficult to work
with mathematically than GR.
Why don't you study MOND results. The MOND people cannot be
pulling numbers out of thin air. You can test them out. You can
try to make a model of DM that will fit MOND. But you won't do
that, you will simply ignore all the evidence, because that's
the easy thing to do.
>
>
> > So we start with the statement that GR is true in a limit of a
> > Quantum Theory of Gravity, which means that GR is not the true
> > picture. So I don't know why Relativists find it so difficult to
> > come to terms with the fact thatMONDworks and proves that the
> > Limit of GR is a few kilo parsecs. Although Pioneer may mean that
> > something is wrong there too. But Pioneer seems to be a fluke
> > rather than an indication of something wrong.
>
> My money is on outgassing and/or asymmetric RTG heat reflection.
>
> MONDworking, for suitable definitions of working, does not prove
> anything other thanMONDis a halfway decent model under certain
> conditions.
I beg to differ here. MOND is not a "halfway decent model", as a
model it is pathetic. It is simply a law, just like Kepler's
Laws, that for some underlying reason works well on the galaxy
scales. We need somebody like Newton or Einstein to explain MOND,
just like Newton explained Kepler's laws and Einstein explained
precession of Mercury. I guess they had it easier, because there
was no scientific establishment to fight with.
http://www.astro.umd.edu/~ssm/mond/daverussellletter.html
The above is a letter that gives 8 reasons why CDM should be
considered falsified within Galaxy limits.
The above also links to an interesting paper. In the initial
version, it concluded that DM+GR cannot explain the correlation.
But by the time it got published the conclusion had changed a
lot. I guess the referee convinced them of the utility of not
ignoring DM in any case ;-). This is a case where the
establishment does prevent publishing of unbiased papers.
http://www.citebase.org/abstract?id=oai%3AarXiv.org%3Aastro-ph%2F0403206
(Cores of Dark Matter Halos Correlate with Disk Scale Lengths)
I don't know what you mean exactly by "suitable definitions of
working", but MOND works very well without any exceptions on the
scale of galaxies. In 80% of galaxies it gives very good fits,
for the rest of the 20%, it is known that there are problems with
the data. And the important thing is that it cannot fit those 20%,
as would be expected for a theory with no free parameters, a0 is
no longer free. Another important thing is that DM models can fit
those 20% cases also to the same degree of accuracy as the other
80%, because of the large number of free parameters.
The onus is on theoretical physicists to find the underlying reason.
Ignoring MOND does not help.
regards,
-anandsr
Ahmed Ouahi, Architect
Yes, indeed!
... However, as along that matter, very little would be possible to activate
anything along that matter as especially, along any nonlinearity neither,
whether it would be an equation along the geometry, which it would be as
follows, for instance : y = r ( x - x² )
Therefore, as along which, every value of x produces a value of y, and the
resulting curve as would show the relation of the two numbers along a range
of a values.
However, along that matter, if x would be small, then y woold be small too,
but larger than x, and the curve would be rising steeply, and if x would be
along the middle of the range, then y would be large, but those levels would
falls, so that if x would be large, then y would be small again.
Therefore, and that is what would produce any modeling along any growth,
whether, as to solve a system of nonlinear differential equations, is almost
an impossible matter, due to their flows and oscillations along that matter
all along, and this is what is all about, a definitely as a matter a fact.
--
Ahmed Ouahi, Architect
Best Regards!
<anan...@gmail.com> wrote in message
news:1174372176.0...@n59g2000hsh.googlegroups.com...
Eric Gisse
..because it *CAN NOT* interact with anything on a macroscopic scale.
I say "CAN NOT" as in "IT CAN NOT, IT IS NOT AN APPROXIMATION" sense.
> Also QED (the Electro Magnetic interaction) also has a weird
> interaction, called entanglement that does weird things even at a
> huge distance, and instantly without coming into conflict with
> superluminal expectations. I guess that is very macroscopic, and
> it very much conflicts with GR. But you can chose to ignore that,
> saying that some GR expectations like causality are not broken.
Entanglement does not exert a force, and does not transmit information
at anything faster than light speed.
>
> I know that you actually mean only the gravitational interaction,
> but in my opinion GR is already broken. I think the accelerated
> expansion of the universe is due to repulsive force of gravitation,
> and that will have to occur only if it increases with gravity. Its
> all speculation, but you know that we don't have the quantum theory
> of gravity.
A repulsive term is easily included in GR - cosmological constant AKA
dark energy.
The only problem is the quantum theory expectation of vacuum energy is
only about 120 orders of magnitude or so from the observed value. This
is a standing problem and I don't expect it to get resolved until a
halfway plausible quantum theory of gravity is formulated.
GR is broken in the "not a quantum theory" sense, *NOT* the "Whups we
are seeing something it cannot explain" sense.
>
> >
> >
> > > > [ii] My personal experience replying EricGisseposts recommended
> > > > avoiding advanced topics. I doubt he has studied QCD.
> >
> > > I wouldn't know about that. But when we are talking about the failures
> > > of GR, then Quantum Theory definitely comes into the picture because
> > > it is GR's biggest failure. Some may say that it is QCD's failure but
> > > I doubt many will see it that way. It is definite that GR will be
> > > found in the limit of a Quantum Theory of Gravity, rather than
> > > QCD to be found in the limit of GR ;-).
> >
> > I think it is premature to worry about GR being the limiting case of
> > anything because we haven't truly found it to be failing. I know your
> > position on dark matter and you know mine. That aside, it must break
> > down _somewhere_ but we haven't actually seen it happen yet.
> >
>
> GR has broken down and miserably. But you are turning a blind eye
> to it. MOND is the indicator. You chose to ignore MOND because you
> cannot explain it. If you could you would have done so. But it is a
> fact that GR+DM cannot explain MOND LAW. It is not possible to
> explain such a tight correlation between the Mass Discrepancies and
> the observed accelerations. If you have a theory you can do so.
> Nobody has done that till now. And nobody who has measured the
> closeness of the correlation will believe that it can be done.
You are ignoring the very papers you have cited to me in researching
MOND - you know, the one you mentioned the other day which explicitly
says that dark matter is required in one form or another?
Personally I think MOND is indirectly mapping the actual dark matter
distribution. I have heard nothing that should dissuade me from that
notion.
>
> You will again say that I am ignoring weak lensing. But I will say
> what's so different about weak lensing, it also shows Mass
> Discrepancy which is also an indication that GR has broken down, we
> are again seeing Mass Discrepancies. Then you will say WMAP, again
> the same Mass Discrepancy. Of course all these mean that there is
> something wrong with GR, but you think that you are seeing different
> confirmation of Dark Matter while the reason for all the
> Mass Discrepancy, is the same. GR does not work in weak gravity
> regimes.
So...when weak lensing manages to show dark matter that doesn't mean
that there is actual matter there, it just means GR is yet again
breaking down in yet another way consistent with there being matter
that doesn't interact via electromagnetism?
I find that even harder to believe. Something is bending light - and
nobody has an even remotely plausible explanation as to take into
account the lensing while simultaneously removing the need for dark
matter. No, TeVeS does not count until it predicts something solid.
>
> To you it doesn't matter that the Mass Discrepancy is increasing
> with the scale. At the Galaxy level it depends on the size and
> density (basically the weakness of gravity), at the cluster level
> it is 10 times. At the Cosmic level it is 100 times. But you will
> see all these similar failings as confirmation of Dark Matter.
Oh come on. The larger the scale under consideration is, the more
visible matter there is.
>
> You will also ignore the only thing that can open your mind.
Versus a preconceived notion [no dark matter] that isn't even agreed
upon by the very papers you cite me?
Denying the weak lensing results is even more closed minded than me
disagreeing with what you think MOND means.
> Because it is so much more easy to live with the status quo.
> You don't want to face the possibility that we don't know any
> theory that can account for weak gravity regimes. This is
> actually a great time for theoretical physicists to try and
> find the correct theory, and quite a few are working towards
> them, and I am not talking about crackpots. Search for papers
> on TeVeS, Conformal Loop Quantum Gravity, AdS/CFT gravity.
Start paring the list down.
Of these, how many of them make testable predictions? No, I don't mean
"soon", I mean "right here <link to paper".
Of these, how many match _already verified_ predictions by general
relativity?
Of the remaining, if any, match up with the area O' interest that is
the bullet cluster while removing the need for dark matter?
> But it is a difficult thing to do, you have to be great at
> mathematics. These theories are much more difficult to work
> with mathematically than GR.
Considering how hard it is to use GR without making a large series of
approximations, I can't help but wonder how many of these theories are
at the point where they can make useful predictions rather than
sweeping statements from toy models.
>
> Why don't you study MOND results. The MOND people cannot be
> pulling numbers out of thin air. You can test them out. You can
> try to make a model of DM that will fit MOND. But you won't do
> that, you will simply ignore all the evidence, because that's
> the easy thing to do.
Of course they aren't.
Keep in mind that MOND offers no explanation as to _why_ gravity is
being screwy, just that it _is_ screwy and that it _is_ a model of the
screwyness. There is no reason offered as to why dark matter can't
simply be modeled by MOND. It isn't as if MOND is based off of bedrock
principles - it is an ad-hoc notion that fits the bill in certain
places.
I'm curious as to what the experiment described here will say.
http://physicsweb.org/articles/news/11/3/12/1
>
> >
> >
> > > So we start with the statement that GR is true in a limit of a
> > > Quantum Theory of Gravity, which means that GR is not the true
> > > picture. So I don't know why Relativists find it so difficult to
> > > come to terms with the fact thatMONDworks and proves that the
> > > Limit of GR is a few kilo parsecs. Although Pioneer may mean that
> > > something is wrong there too. But Pioneer seems to be a fluke
> > > rather than an indication of something wrong.
> >
> > My money is on outgassing and/or asymmetric RTG heat reflection.
> >
> > MONDworking, for suitable definitions of working, does not prove
> > anything other thanMONDis a halfway decent model under certain
> > conditions.
>
> I beg to differ here. MOND is not a "halfway decent model", as a
> model it is pathetic. It is simply a law, just like Kepler's
> Laws, that for some underlying reason works well on the galaxy
> scales. We need somebody like Newton or Einstein to explain MOND,
> just like Newton explained Kepler's laws and Einstein explained
> precession of Mercury. I guess they had it easier, because there
> was no scientific establishment to fight with.
[I swear to god, if google eats this post...]
Do _NOT_ try to pull that "I'm fighting the establishment!" bullshit
with me. The papers you cite are published in reputable journals.
Considering how _often_ MOND is referred to in popular and technical
scientific articles, MOND is decidedly mainstream. The folks in here
who also cry about persecution have wet dreams about being given the
kind of attention that MOND gets in the literature.
MOND is not a law. MOND is a model - it was designed as such, and
remains as such. The fact that it has any sort of success means
something - I think it means that it is keying in on the dark matter
distribution in galaxies at some level.
Think about the weak lensing results - where is most of the dark
matter? Out in the halo. Ignoring weak lensing - where does the dark
matter need to be to smooth out the velocities? Out in the halo. What
is the domain of application for MOND? Out...in the halo, where
gravity is thought to be "weaker".
>
> http://www.astro.umd.edu/~ssm/mond/daverussellletter.html
> The above is a letter that gives 8 reasons why CDM should be
> considered falsified within Galaxy limits.
1) 'Renzo's Rule' indicating that light traces mass.
Why is this a failure? It is important, but I fail to see the
"failure" part.
This explains Renzo's rule, plus it is an example someone working
backwards from Gauss' law [or equivalently, as done in the paper,
Poisson's equation] which I wanted to do previously to finding out
that it was already done. It was done, in my opinion, very nicely as
well!
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
I found this paper to be very, very informative in both explaining
both MOND and dark matter as applied to galactic scales. The nature of
the fits is now less opaque, which I found helpful. Plus it gave
support and a direct reference to that large number of MOND fits you
alluded to previously.
You will find the paper very informative as well, so I'm not going to
try to summarize it. But both our positions allowable - either MOND is
correct as-is or the distribution of dark matter in galaxies gives
rise to MOND.
Let me be clear - I accepted before and accept even more now that MOND
is pointing to something important. What we seem to disagree on is
_what_ that important thing is.
2) Disk-Halo conspiracy
http://arxiv.org/PS_cache/astro-ph/pdf/9610/9610188.pdf [PDF is
slightly glitchy...]
One of the conclusions I thought was most intriguing was that the dark
matter halo shape under that model was something that was reasonably
constant.
It [disk halo conspiracy] is touched on indirectly as well by the
previous paper. Given there is an alternative explanation that is
entirely plausible, I don't see why folks are adopting the CDM
WROOOOOOOOONG stance. So far, it looks like the worst case is that the
CDM model needs tweaking - which doesn't surprise me, I do not believe
it was even geared as a model for scales so small.
3,4) No idea what is even being talked about since I don't have that
paper onhand.
5-8) Talked about with _extensive_ detail in the first paper I linked
you.
The linked paper has the same content - same equations, same data,
same conclusions as the first paper as well.
What folks seem to be missing is that success of MOND and success of
dark matter are not mutually contradictory goals. MOND seems to lend
itself fairly easily to a dark matter explanation, despite how angry
that probably makes the MOND crew.
The constant inclusion of the virial mass [200x universe critical
density] and the size associated with it amuses me for some odd
reason...I don't find anything wrong or objectionable, it just amuses
me.
>
> The above also links to an interesting paper. In the initial
> version, it concluded that DM+GR cannot explain the correlation.
> But by the time it got published the conclusion had changed a
> lot. I guess the referee convinced them of the utility of not
> ignoring DM in any case ;-). This is a case where the
> establishment does prevent publishing of unbiased papers.
That is BULLSHIT and you know it.
The conclusions reached thus far do not eliminate dark matter. In
fact, they refine dark matter as a concept because the only thing
really used is the fact that MOND is, observationally, a good fit.
>
> http://www.citebase.org/abstract?id=oai%3AarXiv.org%3Aastro-ph%2F0403206
> (Cores of Dark Matter Halos Correlate with Disk Scale Lengths)
Yes, yes. More of the same.
>
> I don't know what you mean exactly by "suitable definitions of
> working", but MOND works very well without any exceptions on the
> scale of galaxies. In 80% of galaxies it gives very good fits,
> for the rest of the 20%, it is known that there are problems with
> the data. And the important thing is that it cannot fit those 20%,
> as would be expected for a theory with no free parameters, a0 is
> no longer free. Another important thing is that DM models can fit
> those 20% cases also to the same degree of accuracy as the other
> 80%, because of the large number of free parameters.
The number of free parameters isn't that big and you know it, if you
have actually been reading the papers you have been citing me.
My remark of "suitable definitions of working" was _before_ I saw the
first paper I linked - it was exactly what I was looking for. I wanted
something that gave me a broad overview of MOND results, rather than
personally stitching together a hundred results. I was unable to
determine how much of the swooning was over fanboyism or actual data,
which now I know and I adjust the remark accordingly.
>
> The onus is on theoretical physicists to find the underlying reason.
> Ignoring MOND does not help.
That much is now obvious. MOND is an excellent model for individual
galaxies, though I _suspect_ it fails for galaxies that are products
of or are in various stages of collision [eg, bullet cluster].
Keep in mind that nothing you have shown me or what I have found
conclusively, or even most likely, makes dark matter an incorrect
model. In fact, everything I have seen thus far either supports or
refines dark matter. Using the MOND fits along with the empirical data
gives some nice constraints on entirely plausible distributions of
dark mater where there were none before, which is quite useful.
>
> regards,
> -anandsr
Eric Gisse
wrote:
[...]
I think it is time to, once again, ask you why you even bother posting
on this newsgroup when you have no grasp of physics at any level.
Ahmed Ouahi, Architect
It would be this, that it could makes you to feel better, or the pain is
somewhere else!?
--
Ahmed Ouahi, Architect
Think About That!
"Eric Gisse" <jow...@gmail.com> wrote in message
news:1174379752.7...@n76g2000hsh.googlegroups.com...
Eric Gisse
wrote:
> It would be this, that it could makes you to feel better, or the pain is
> somewhere else!?
Quiet, top-posting nutter.
>
> --
> Ahmed Ouahi, Architect
> Think About That!
>
> "EricGisse" <jowr...@gmail.com> wrote in message
Ahmed Ouahi, Architect
One way or an other, you do have an infinite empty space, due to your own
emptiness, the reason, that you are an empty from upstairs, as along your
case, that is a simply what is all about.
--
Ahmed Ouahi, Architect
Think About That!
"Eric Gisse" <jow...@gmail.com> wrote in message
news:1174457567.2...@d57g2000hsg.googlegroups.com...
Eric Gisse
wrote:
> One way or an other, you do have an infinite empty space, due to your own
> emptiness, the reason, that you are an empty from upstairs, as along your
> case, that is a simply what is all about.
Be quiet, spewing moron.
>
> --
> Ahmed Ouahi, Architect
> Think About That!
>
> "Eric Gisse" <jowr...@gmail.com> wrote in message
anan...@gmail.com
too big. Note to myself use an editor ;-).
On Mar 20, 1:34 pm, "Eric Gisse" <jowr...@gmail.com> wrote:
> anands...@gmail.com wrote:
> Denying the weak lensing results is even more closed minded than me
> disagreeing with what you thinkMONDmeans.
I never denied weak lensing results. I just said that if MOND can
explain the Mass Discrepency in Galaxies, it is not very difficult to
assume that a proper quantum theory will account for the Mass
Discrepency in weak lensing data also.
I also am not against Dark Matter. I just dislike Cold Dark Matter. In
my opinion Cold Dark Matter means that it is not moving much. And if
there are huge amounts of it, it will clump. If it clumps there will
be collisions. How does one detect these collisions, if they do not
couple electromagnetically.
Neutrinos avoid this problem by being hot, which prevents their
coupling together.
Till yesterday I used to think that MOND will fail in Clusters but now
I think that MOND should apply within any gravitationally bound
structure. So now I think MOND should survive the KATRIN test. And
Neutrino oscillation will be able to provide the missing mass. But it
may not be true, and there may be another neutrino like particle that
is also present.
The thing is that all the evidence for Dark Matter is just Mass
Discrepency. The only proper evidence we have found for Dark Matter
is in Bullet Cluster and the dark galaxies. Both of these can be
explained currently by massive and fast Neutrinos. If neutrinos have
mass then they can make stable structures of Cluster sizes, given
MONDian force.
>
> > Because it is so much more easy to live with the status quo.
> > You don't want to face the possibility that we don't know any
> > theory that can account for weak gravity regimes. This is
> > actually a great time for theoretical physicists to try and
> > find the correct theory, and quite a few are working towards
> > them, and I am not talking about crackpots. Search for papers
> > on TeVeS, Conformal Loop Quantum Gravity, AdS/CFT gravity.
>
> Start paring the list down.
>
> Of these, how many of them make testable predictions? No, I don't mean
> "soon", I mean "right here <link to paper".
All of them.
It is only DM that does not make testable prediction. Others can be
falsified. Mannheim's Conformal Gravity has already been falsified by
Bullet Cluster. But now I know what was wrong with it. He was using
dS/CFT instead of AdS/CFT. Now M.B.Paranjape and A.Edery are taking
that work forward, using AdS/CFT. But the work must now be done from
the beginning.
We also have LQG. I don't think that you believe that they are not
trying to make any testable predictions. It is the only viable Quantum
Gravity Theory. I don't consider String Theory at all. LQG till now
had been using GR. Which is not working very well. The main problem
is that Quantum theories are fundamentally at odds with any sort of
scale. There are a couple of LQG researchers that are moving towards
using Conformal Invariance instead of Lorentz Invariance. I am sure
something good will come out of it.
TeVeS is making testable predictions. I personally don't like TeVeS,
but it is not a bad idea. We may come up with a law for weak lensing
through it. This work is also needed for convincing GR proponents that
DM in Galaxies is redundant.
>
> Of these, how many match _already verified_ predictions by general
> relativity?
Conformal gravity matches GR very well in strong gravity. Nearly well
with MOND in the galaxies. Used to explain Cluster dynamics, but now
with the discovery of unambiguous proof of DM in Clusters will fail
there. And hence will be falsified.
MOND/TeVeS works well in strong gravity, as they are basically same as
GR. Works very well in Galaxies. Predicts HDM in Clusters, as required
by Bullet Cluster. Also is not against Dark Galaxies. It can be
falsified, but has not been falsified yet.
LQG is still in its infancy. Will have to wait for some testable
predictions. They have some explanation for the Ohmygod particles, but
I think little else.
>
> Of the remaining, if any, match up with the area O' interest that is
> the bullet cluster while removing the need for dark matter?
There is no need to remove Dark Matter in Bullet Cluster. It is an
unambiguous observation that Dark Matter exists in Bullet Cluster.
Also MOND has been predicting double the mass in most Clusters, which
should be the same Dark Matter which we see in Bullet Cluster. But
that doesn't mean that it has to be CDM, it could be HDM.
>
> > But it is a difficult thing to do, you have to be great at
> > mathematics. These theories are much more difficult to work
> > with mathematically than GR.
>
> Considering how hard it is to use GR without making a large series of
> approximations, I can't help but wonder how many of these theories are
> at the point where they can make useful predictions rather than
> sweeping statements from toy models.
Just imagine how hard it will be using AdS/CFT for the calculations.
It is an Order Four theory, much more complex than the Order 2 GR. It
is possibly the biggest reason why we don't have a viable Quantum
Gravity theory yet.
> > Why don't you studyMONDresults. TheMONDpeople cannot be
> > pulling numbers out of thin air. You can test them out. You can
> > try to make a model of DM that will fitMOND. But you won't do
> > that, you will simply ignore all the evidence, because that's
> > the easy thing to do.
>
> Of course they aren't.
>
> Keep in mind thatMONDoffers no explanation as to _why_ gravity is
> being screwy, just that it _is_ screwy and that it _is_ a model of the
> screwyness. There is no reason offered as to why dark matter can't
> simply be modeled byMOND. It isn't as ifMONDis based off of bedrock
> principles - it is an ad-hoc notion that fits the bill in certain
> places.
MOND need not offer any explanation to be useful. It's main job is to
show that gravity is being screwy. The work is cut out for the
theoretical physicists to explain why it is screwy. But most are just
hoping that DM can explain anything. While even after 25 years there
is no model of DM that can explain MOND relationship.
> I'm curious as to what the experiment described here will say.
>
> http://physicsweb.org/articles/news/11/3/12/1
I don't know what they are trying to do. I think the person doesn't
know MOND. MOND will apply only when the total accelaration due to
gravity drops below a0. I don't know how on earth he found such a
place on earth. On earth acceleration due to gravity cannot go much
below or above g. Even earth can never expect gravity much less than
a0, unless it gets between Jupiter and Sun in such a way that both the
accelarations cancel exactly. Even then Moon will not let it fall
below a0.
The only place MOND can be tested is the L4 and L5 areas. In these
areas gravity due to Sun and Earth+Moon cancels exactly, so there must
be a smaller area within it where the total gravity falls below a0.
This area is called a Mondian bubble. And it is the nearest place
where MOND can be verified. The hope is that the bubble will be big
enough to accomodate a test machine ;-).
> Do _NOT_ try to pull that "I'm fighting the establishment!" bullshit
> with me. The papers you cite are published in reputable journals.
> Considering how _often_MONDis referred to in popular and technical
> scientific articles,MONDis decidedly mainstream. The folks in here
> who also cry about persecution have wet dreams about being given the
> kind of attention thatMONDgets in the literature.
Sorry, will not do it again. It was an interesting comment in the
letter.
> MONDis not a law.MONDis a model - it was designed as such, and
> remains as such. The fact that it has any sort of success means
> something - I think it means that it is keying in on the dark matter
> distribution in galaxies at some level.
MOND is a law, it is only a single equation, just like Keplers laws
where. Or Newton's laws were. Mondian models are created to fit the
galaxy rotation curves. But these are not MOND. They are built over
MOND.
> Think about the weak lensing results - where is most of the dark
> matter? Out in the halo. Ignoring weak lensing - where does the dark
> matter need to be to smooth out the velocities? Out in the halo. What
> is the domain of application forMOND? Out...in the halo, where
> gravity is thought to be "weaker".
I would think if most of the matter is out in a halo, the lens will
not be properly convex. It will be convex overall but near the center
there will be a concave circular portion. This will result in the
center part concentrating more light than a normal convex lens, so you
should see a brighter spot at the center of such a lens. Does any weak
lensing show this artifact.
> Let me be clear - I accepted before and accept even more now thatMOND
> is pointing to something important. What we seem to disagree on is
> _what_ that important thing is.
Well now I can rejoice ;-). We have reached the most important part of
the discussion. You accept MOND effect as real.
Now consider the following points
1) MOND is real. This means that Dark Matter has no degrees of freedom
within a galaxy. This must be true because MOND can predict the
rotation curve based on normal matter alone, so if DM gives rise to
MOND, it cannot have any degrees of freedom. It must go where normal
matter tells it to.
2) We cannot be living in a special epoch, when DM matches MOND
everywhere. It must have been true for a very long time in the past.
And will
continue to do so for a very long time in the future.
3) Dark Matter cannot have been put by an intelligent agent to test
our faith ;-). It must have arisen based on some mechanism and using
the mechanisms of GR must have moved in such a way to always bring out
the MOND phenomenology.
4) If you see the 3 points above you see that DM in galaxies is
superfluous. It must satisfy too many features to be true, and top of
that it has no degrees of freedom, which makes it a superflous
concept. This is where Occam's Razor steps in to say that DM is not
simpler than MOND, and so must not be the true picture of the world.
>
> 2) Disk-Halo conspiracy
>
> http://arxiv.org/PS_cache/astro-ph/pdf/9610/9610188.pdf[PDF is
> slightly glitchy...]
>
> One of the conclusions I thought was most intriguing was that the dark
> matter halo shape under that model was something that was reasonably
> constant.
>
> It [disk halo conspiracy] is touched on indirectly as well by the
> previous paper. Given there is an alternative explanation that is
> entirely plausible, I don't see why folks are adopting the CDM
> WROOOOOOOOONG stance. So far, it looks like the worst case is that the
> CDM model needs tweaking - which doesn't surprise me, I do not believe
> it was even geared as a model for scales so small.
What is your entirely plausible alternative explanation. I am dying to
know ;-).
> What folks seem to be missing is that success ofMONDand success of
> dark matter are not mutually contradictory goals.MONDseems to lend
> itself fairly easily to a dark matter explanation, despite how angry
> that probably makes theMONDcrew.
On the contrary, MOND is expected to make a lot of Relativists very
angry when they find that no DM model can work ;-).
>
> The constant inclusion of the virial mass [200x universe critical
> density] and the size associated with it amuses me for some odd
> reason...I don't find anything wrong or objectionable, it just amuses
> me.
>
> > I don't know what you mean exactly by "suitable definitions of
> > working", butMONDworks very well without any exceptions on the
> > scale of galaxies. In 80% of galaxies it gives very good fits,
> > for the rest of the 20%, it is known that there are problems with
> > the data. And the important thing is that it cannot fit those 20%,
> > as would be expected for a theory with no free parameters, a0 is
> > no longer free. Another important thing is that DM models can fit
> > those 20% cases also to the same degree of accuracy as the other
> > 80%, because of the large number of free parameters.
>
> The number of free parameters isn't that big and you know it, if you
> have actually been reading the papers you have been citing me.
Even 2 free parameters are too many when a competing theory can fit
the data without any free parameter. And most DM theories require 3 or
4 parameters. Remember that DM theories can fit the 20% cases where
the data is problematic. This indicates that the free parameters are
enough to fit any rotation curve even if they are not from a real
galaxy. This is what proves that there are too many parameters. Any
good model is one which is not able to work with bad data. DM models
are not good models.
> > The onus is on theoretical physicists to find the underlying reason.
> > IgnoringMONDdoes not help.
>
> That much is now obvious.MONDis an excellent model for individual
> galaxies, though I _suspect_ it fails for galaxies that are products
> of or are in various stages of collision [eg, bullet cluster].
>
> Keep in mind that nothing you have shown me or what I have found
> conclusively, or even most likely, makes dark matter an incorrect
> model. In fact, everything I have seen thus far either supports or
> refines dark matter. Using theMONDfits along with the empirical data
> gives some nice constraints on entirely plausible distributions of
> dark mater where there were none before, which is quite useful.
I and possibly all of the MOND proponents are dying to know an
entirely plausible distribution of DM that can fit MOND.
Just remember that Occam's Razor is against you ;-).
regards,
-anandsr
gdew...@gmail.com
gdew...@gmail.com
anan...@gmail.com
anan...@gmail.com wrote:
> Google ate my post. It seems that it happens when the message is
> too big. Note to myself use an editor ;-).
>
>
> On Mar 20, 1:34 pm, "Eric Gisse" <jowr...@gmail.com> wrote:
> > anands...@gmail.com wrote:
> > I'm curious as to what the experiment described here will say.
> >
> > http://physicsweb.org/articles/news/11/3/12/1
>
> I don't know what they are trying to do. I think the person doesn't
> know MOND. MOND will apply only when the total accelaration due to
> gravity drops below a0. I don't know how on earth he found such a
> place on earth. On earth acceleration due to gravity cannot go much
> below or above g. Even earth can never expect gravity much less than
> a0, unless it gets between Jupiter and Sun in such a way that both the
> accelarations cancel exactly. Even then Moon will not let it fall
> below a0.
>
> The only place MOND can be tested is the L4 and L5 areas. In these
This should be L1 point. Not L4 and L5. The forces don't cancel at
L4 and L5. They cancel at L1. Sorry for the mistake.
> areas gravity due to Sun and Earth+Moon cancels exactly, so there must
> be a smaller area within it where the total gravity falls below a0.
> This area is called a Mondian bubble. And it is the nearest place
> where MOND can be verified. The hope is that the bubble will be big
> enough to accomodate a test machine ;-).
>
regards,
-anandsr
Eric Gisse
wrote:
> On Mar 20, 10:34 am, "Eric Gisse" <jowr...@gmail.com> wrote:
>
> > Personally I think MOND is indirectly mapping the actual dark matter
> > distribution. I have heard nothing that should dissuade me from that
> > notion.
>
> like a ***mathematical*** artifact. Since rho_DM has only mathematical
> sense DM does not need to be experimentally searched (it has never
> appeared no matter how many time and effort devoted to search DM) and
> no extension of SM of particle physicis is needed.
Do you say things like this after carefully ignoring evidence that
disagrees with your interpretation?
If dark matter is an artifact, why is it that including dark matter
makes for such a good model of the large scale of the universe? How
about explaining _all_ of the weak lensing results of the past 5 years
or so that explicitly map out the distributions of dark matter?
>
> > MOND is not a law. MOND is a model - it was designed as such, and
> > remains as such. The fact that it has any sort of success means
> > something - I think it means that it is keying in on the dark matter
> > distribution in galaxies at some level.
>
> MOND is a law, not a model nor a theory.
By what stretch of the imagination do you say that?
MOND _fails_ in the bullet cluster and it was invented as a _model_ to
explain rotation curves.
>
> > Think about the weak lensing results - where is most of the dark
> > matter? Out in the halo. Ignoring weak lensing - where does the dark
> > matter need to be to smooth out the velocities? Out in the halo. What
> > is the domain of application for MOND? Out...in the halo, where
> > gravity is thought to be "weaker".
>
> When R is larger the MOND law [1 / R] is stronger than [1 / R^2]. Why
> do you claim gravity is weaker when is stronger?
It might be a good idea to explain what the hell you are talking
about.
>
> > What folks seem to be missing is that success of MOND and success of
> > dark matter are not mutually contradictory goals. MOND seems to lend
> > itself fairly easily to a dark matter explanation, despite how angry
> > that probably makes the MOND crew.
>
> Fine, therefore a theory (MOND) claiming that DM does not exits is not
> -for you-contradictory with a theory (GR+DM) claiming existence for
> DM.
MOND makes no such claim. The proponents of MOND make the claim - MOND
itself is simply a model. The proponents think that if MOND works,
there is no dark matter while ignoring the extremely likely
possibility that MOND is mapping out dark matter.
>
> > > The onus is on theoretical physicists to find the underlying reason.
> > > Ignoring MOND does not help.
>
> > That much is now obvious. MOND is an excellent model for individual
> > galaxies, though I _suspect_ it fails for galaxies that are products
> > of or are in various stages of collision [eg, bullet cluster].
>
> Pure GR fails for both galaxies and clusters.
>
> GR+DM is not fine for galaxies and fails for bullet cluster unless
> invoking now a unproven _ad hoc_ hypotesis about existence of a new
> kind of interaction (NGI).
Go go gadget intellectual dishonesty.
You _KNOW_, assuming you actually read the paper, that the 'new kind
of interaction' is something that creeps in because the models they
picked can't quite explain how fast some parts of the bullet cluster
are moving by about 20%. That in no way means a 'new kind of
interaction' is necessary until a hell of a lot more research is done.
>
> History: GR --> [GR + DM] --> [GR + DM + NGI] --> [GR + DM + NGI
> + ??]
>
> How many unproven _ad hoc_ hypotesis will be needed before relativist
> comunity begin to accept that GR is not so good like they believe?
How many unproven hypotheses [eg: new kinds of interaction] will you
latch on to? Every time someone comes up with an idea that contradicts
relativity - no matter how flimsy - you take it as the gospel truth.
Relativity has earned its' place in the scientific community. The very
tool that allows folks to probe the nature of dark matter -
gravitational lensing - is a relativity prediction.
Eric Gisse
> Google ate my post. It seems that it happens when the message is
> too big. Note to myself use an editor ;-).
You should thank Juan R, he finally served a purpose. I had this reply
90% finished on my desktop, then forgot about it.
>
>
> On Mar 20, 1:34 pm, "Eric Gisse" <jowr...@gmail.com> wrote:
> > anands...@gmail.com wrote:
> > Denying the weak lensing results is even more closed minded than me
> > disagreeing with what you thinkMONDmeans.
>
> I never denied weak lensing results. I just said that if MOND can
> explain the Mass Discrepency in Galaxies, it is not very difficult to
> assume that a proper quantum theory will account for the Mass
> Discrepency in weak lensing data also.
So...shift the explanation of something that is unquestionably
observed and already has a well-understood explanation into the
indefinite future?
There is _no_ reason to doubt that our interpretation of the weak
lensing results is false. There is matter there and it curves light
and we detect it. That is remarkably direct compared to other
cosmological observations that are *heavily* model-dependent.
>
> I also am not against Dark Matter. I just dislike Cold Dark Matter. In
> my opinion Cold Dark Matter means that it is not moving much. And if
> there are huge amounts of it, it will clump. If it clumps there will
> be collisions. How does one detect these collisions, if they do not
> couple electromagnetically.
Lensing.
Old in theory, new in implementation. I was just reading an article
about this earlier today - it has been postulated for years but has
been insanely difficult to apply because essentially what is being
measured is the degree of correlation between how elliptic galaxies
are over an area. Being able to reliably apply this to a required
patch of the sky was unable to be performed until the deployment of
CCDs in astronomy, and the measurements themselves have only been done
within the last 5 years or so.
There has already been an article published that gave an upper bound
on the mass of the clumps in a certain galaxy [I believe I gave you
the link before, actually] that was on the order of an Earth mass.
That result also neatly ruled out things like failed/dwarf stars,
large planets, and any class of black hole other than primordial. At
least in that one specific area - sample size of one and all.
>
> Neutrinos avoid this problem by being hot, which prevents their
> coupling together.
Neutrinos avoid the problem by having an insanely small scattering
cross section and by traveling within epsilon of light speed for
pretty much any plausible amount of energy. They avoid the problem so
well that they are horrible dark matter candidates - not enough of
them can be produced, and they are not capable of binding to galaxies
considering how fast they would be traveling. Neutrino dark matter
would form a background, not a halo.
>
> Till yesterday I used to think that MOND will fail in Clusters but now
> I think that MOND should apply within any gravitationally bound
> structure. So now I think MOND should survive the KATRIN test. And
> Neutrino oscillation will be able to provide the missing mass. But it
> may not be true, and there may be another neutrino like particle that
> is also present.
KATRIN isn't and never will be a test of MOND. Neutrino oscillations
simply shift the flavors around - they do not add mass. Neutrino mass
is constrained to be very tiny, and if the L-CDM model is even close
to being reasonable the total masses of all neutrinos is less than an
eV.
At any rate, a new type of neutrino is pretty much excluded by both
model [Standard / L-CDM], and a large body observation. Current fits
to the WMAP data only work for 3 neutrinos [this is discussed in the
implications for cosmology paper which I have linked to you before]
and Earth-based observations place the count at 3 as well.
http://pdg.lbl.gov/2006/reviews/lightnu_s007.pdf
>
> The thing is that all the evidence for Dark Matter is just Mass
> Discrepency. The only proper evidence we have found for Dark Matter
> is in Bullet Cluster and the dark galaxies. Both of these can be
> explained currently by massive and fast Neutrinos. If neutrinos have
> mass then they can make stable structures of Cluster sizes, given
> MONDian force.
No! Neutrinos _can not do it_!
Look back at that paper I linked to you the other day - remember how
everything was consistent with a HALO of dark matter? There are simply
not enough neutrinos and the ones whizzing around simply have too much
energy to be bound.
http://www.astro.ucla.edu/~wright/BBNS.html
The nucleosynthesis model is working thus far - and neutrino dark
matter is massively incompatible with it unless you have a real good
reason for explaining how neutrinos traveling nigh-indistinguishably
from lightspeed become bound to a galaxy.
>
> >
> > > Because it is so much more easy to live with the status quo.
> > > You don't want to face the possibility that we don't know any
> > > theory that can account for weak gravity regimes. This is
> > > actually a great time for theoretical physicists to try and
> > > find the correct theory, and quite a few are working towards
> > > them, and I am not talking about crackpots. Search for papers
> > > on TeVeS, Conformal Loop Quantum Gravity, AdS/CFT gravity.
> >
> > Start paring the list down.
> >
> > Of these, how many of them make testable predictions? No, I don't mean
> > "soon", I mean "right here <link to paper".
>
> All of them.
My, that was quick. I thought LQG still had something on the order of
10^50 solutions?
>
> It is only DM that does not make testable prediction. Others can be
> falsified. Mannheim's Conformal Gravity has already been falsified by
> Bullet Cluster. But now I know what was wrong with it. He was using
> dS/CFT instead of AdS/CFT. Now M.B.Paranjape and A.Edery are taking
> that work forward, using AdS/CFT. But the work must now be done from
> the beginning.
Both DM and MOND were hypotheses created to explain galactic rotation
curves. MOND, however, can't handle the large scale structure of the
universe while DM is an fundamental part in something that makes a
very, very good fit. Remember what you told me - something that fits
that well has to have some fashion of truth to it?
>
> We also have LQG. I don't think that you believe that they are not
> trying to make any testable predictions. It is the only viable Quantum
> Gravity Theory. I don't consider String Theory at all. LQG till now
> had been using GR. Which is not working very well. The main problem
> is that Quantum theories are fundamentally at odds with any sort of
> scale. There are a couple of LQG researchers that are moving towards
> using Conformal Invariance instead of Lorentz Invariance. I am sure
> something good will come out of it.
LQG is loosely based off of GR, but I know precious little about it.
It is yet another approach to doing quantum theory in curved
spacetime. Quantum theory just does not play nice with gravitation.
It isn't that I don't believe they are _trying_, it is that I don't
believe they are _able_ to do anything but make general statements.
>
> TeVeS is making testable predictions. I personally don't like TeVeS,
> but it is not a bad idea. We may come up with a law for weak lensing
> through it. This work is also needed for convincing GR proponents that
> DM in Galaxies is redundant.
I wish them the best of luck - they have some severe hurdles to pass
through.
They have to describe *all* of the following self-consistently:
1) Make dark matter irrelevant.
2) Explain the bullet cluster.
3) A part of 2 - explain why current weak lensing results are so, so
wrong.
4) Do 3 without invalidating solar system tests of strong lensing.
5) Stay relativistic - not doing so makes a large, large body of
astrophysical observation and terrestrial experiment mad at you.
>
> >
> > Of these, how many match _already verified_ predictions by general
> > relativity?
>
> Conformal gravity matches GR very well in strong gravity. Nearly well
> with MOND in the galaxies. Used to explain Cluster dynamics, but now
> with the discovery of unambiguous proof of DM in Clusters will fail
> there. And hence will be falsified.
Whups. 2 out of 3 ain't bad.
>
> MOND/TeVeS works well in strong gravity, as they are basically same as
> GR. Works very well in Galaxies. Predicts HDM in Clusters, as required
> by Bullet Cluster. Also is not against Dark Galaxies. It can be
> falsified, but has not been falsified yet.
Careful when you say 'required'. I have been trying to distinguish
between things that are observationally true and which are required to
be true within a specific hypothesis.
Hot neutrinos - it isn't something required by MOND, it is a
*hypothesis* that is added in to explain the bullet cluster within the
context of MOND.
>
> LQG is still in its infancy. Will have to wait for some testable
> predictions. They have some explanation for the Ohmygod particles, but
> I think little else.
Last I heard, cosmic rays are getting blamed on black holes. We
already know jets can send planet-massed chunks of matter at a large
fraction of c...
>
> >
> > Of the remaining, if any, match up with the area O' interest that is
> > the bullet cluster while removing the need for dark matter?
>
> There is no need to remove Dark Matter in Bullet Cluster. It is an
> unambiguous observation that Dark Matter exists in Bullet Cluster.
Zuh?
Are folks folks going with the King Solomon approach and splitting the
difference? Arguing both dark matter *AND* MOND is a little
contradictory to me.
> Also MOND has been predicting double the mass in most Clusters, which
> should be the same Dark Matter which we see in Bullet Cluster. But
> that doesn't mean that it has to be CDM, it could be HDM.
...and how many HDM candidates are there? There aren't that many
stable particles which don't interact electromagnetically...
>
> >
> > > But it is a difficult thing to do, you have to be great at
> > > mathematics. These theories are much more difficult to work
> > > with mathematically than GR.
> >
> > Considering how hard it is to use GR without making a large series of
> > approximations, I can't help but wonder how many of these theories are
> > at the point where they can make useful predictions rather than
> > sweeping statements from toy models.
>
> Just imagine how hard it will be using AdS/CFT for the calculations.
> It is an Order Four theory, much more complex than the Order 2 GR. It
> is possibly the biggest reason why we don't have a viable Quantum
> Gravity theory yet.
I am not sure in what context "order 2 GR" is meant. GR's principle
equations are based on rank 2 tensors, but tensors of higher and lower
rank are scattered hither tither and yon. The differential equations
are second order, maybe that is what is meant.
The PDE folks will love a theory that is based off of fourth order
differential equations. "FINALLY! Something other than bending beams -
getting so fucking tired of those!"
>
> > > Why don't you studyMONDresults. TheMONDpeople cannot be
> > > pulling numbers out of thin air. You can test them out. You can
> > > try to make a model of DM that will fitMOND. But you won't do
> > > that, you will simply ignore all the evidence, because that's
> > > the easy thing to do.
> >
> > Of course they aren't.
> >
> > Keep in mind thatMONDoffers no explanation as to _why_ gravity is
> > being screwy, just that it _is_ screwy and that it _is_ a model of the
> > screwyness. There is no reason offered as to why dark matter can't
> > simply be modeled byMOND. It isn't as ifMONDis based off of bedrock
> > principles - it is an ad-hoc notion that fits the bill in certain
> > places.
>
> MOND need not offer any explanation to be useful. It's main job is to
> show that gravity is being screwy. The work is cut out for the
> theoretical physicists to explain why it is screwy. But most are just
> hoping that DM can explain anything. While even after 25 years there
> is no model of DM that can explain MOND relationship.
MOND is a model, and as such it has served excellently. I think MOND
should be the model for dark matter hosted in galaxies. Clusters not
so much.
>
> > I'm curious as to what the experiment described here will say.
> >
> > http://physicsweb.org/articles/news/11/3/12/1
>
> I don't know what they are trying to do. I think the person doesn't
> know MOND. MOND will apply only when the total accelaration due to
> gravity drops below a0. I don't know how on earth he found such a
> place on earth. On earth acceleration due to gravity cannot go much
> below or above g. Even earth can never expect gravity much less than
> a0, unless it gets between Jupiter and Sun in such a way that both the
> accelarations cancel exactly. Even then Moon will not let it fall
> below a0.
I think the idea is silly but worth doing since some MOND proponents
think it is worth doing. You already explained why I think it is silly
- but if they want to go ahead, *shrug*.
>
> The only place MOND can be tested is the L4 and L5 areas. In these
> areas gravity due to Sun and Earth+Moon cancels exactly, so there must
> be a smaller area within it where the total gravity falls below a0.
> This area is called a Mondian bubble. And it is the nearest place
> where MOND can be verified. The hope is that the bubble will be big
> enough to accomodate a test machine ;-).
>
> > Do _NOT_ try to pull that "I'm fighting the establishment!" bullshit
> > with me. The papers you cite are published in reputable journals.
> > Considering how _often_MONDis referred to in popular and technical
> > scientific articles,MONDis decidedly mainstream. The folks in here
> > who also cry about persecution have wet dreams about being given the
> > kind of attention thatMONDgets in the literature.
>
> Sorry, will not do it again. It was an interesting comment in the
> letter.
>
> > MONDis not a law.MONDis a model - it was designed as such, and
> > remains as such. The fact that it has any sort of success means
> > something - I think it means that it is keying in on the dark matter
> > distribution in galaxies at some level.
>
> MOND is a law, it is only a single equation, just like Keplers laws
> where. Or Newton's laws were. Mondian models are created to fit the
> galaxy rotation curves. But these are not MOND. They are built over
> MOND.
The whole discussion about whether or not it is a law irritates me
because it serves no purpose. It is semantic quibbling.
>
> > Think about the weak lensing results - where is most of the dark
> > matter? Out in the halo. Ignoring weak lensing - where does the dark
> > matter need to be to smooth out the velocities? Out in the halo. What
> > is the domain of application forMOND? Out...in the halo, where
> > gravity is thought to be "weaker".
>
> I would think if most of the matter is out in a halo, the lens will
> not be properly convex. It will be convex overall but near the center
> there will be a concave circular portion. This will result in the
> center part concentrating more light than a normal convex lens, so you
> should see a brighter spot at the center of such a lens. Does any weak
> lensing show this artifact.
I don't know.
It is not clear to me how the distribution of matter would influence
the lens. The true theory and application of weak lensing on galactic
scales is not as known to me as I would like.
>
> > Let me be clear - I accepted before and accept even more now thatMOND
> > is pointing to something important. What we seem to disagree on is
> > _what_ that important thing is.
>
> Well now I can rejoice ;-). We have reached the most important part of
> the discussion. You accept MOND effect as real.
Yes and no.
I accept that MOND is an accurate model over a surprisingly large
sample set. I rationalize it thusly: all galaxies appear to have
formed in the same way, more or less. So it stands to reason that DM
will be the same in each galaxy [less collisions and exotic
circumstances] if not more so due to the lack of interaction.
I do not accept that MOND is a physical theory unto itself. There are
too many results from weak lensing that make dark matter convincing in
my eye, as well as its' utility in cosmological modeling. The MOND
folkes probably would _not_ like that position.
>
> Now consider the following points
> 1) MOND is real. This means that Dark Matter has no degrees of freedom
> within a galaxy. This must be true because MOND can predict the
> rotation curve based on normal matter alone, so if DM gives rise to
> MOND, it cannot have any degrees of freedom. It must go where normal
> matter tells it to.
I think there is an element of truth to that, but not exactly as
written.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
It appears that DM baryonic matter are nicely correlated.
>
> 2) We cannot be living in a special epoch, when DM matches MOND
> everywhere. It must have been true for a very long time in the past.
> And will
> continue to do so for a very long time in the future.
I don't see why not - at least, the matching part. I am yet to hear a
convincing explanation as to why MOND *can't* be represenative of dark
matter.
>
> 3) Dark Matter cannot have been put by an intelligent agent to test
> our faith ;-). It must have arisen based on some mechanism and using
> the mechanisms of GR must have moved in such a way to always bring out
> the MOND phenomenology.
Yea I think we can both agree on that one.
>
> 4) If you see the 3 points above you see that DM in galaxies is
> superfluous. It must satisfy too many features to be true, and top of
> that it has no degrees of freedom, which makes it a superflous
> concept. This is where Occam's Razor steps in to say that DM is not
> simpler than MOND, and so must not be the true picture of the world.
I don't think you are applying Occam's razor properly. DM as a concept
is quite simple - there is matter we can't see that explains otherwise
contradictory observations. The concept is not superfluous because
there is no alternative _physical_ explanation, nor is there an
explanation of lensing results.
>
> >
> > 2) Disk-Halo conspiracy
> >
> > http://arxiv.org/PS_cache/astro-ph/pdf/9610/9610188.pdf[PDF is
> > slightly glitchy...]
> >
> > One of the conclusions I thought was most intriguing was that the dark
> > matter halo shape under that model was something that was reasonably
> > constant.
> >
> > It [disk halo conspiracy] is touched on indirectly as well by the
> > previous paper. Given there is an alternative explanation that is
> > entirely plausible, I don't see why folks are adopting the CDM
> > WROOOOOOOOONG stance. So far, it looks like the worst case is that the
> > CDM model needs tweaking - which doesn't surprise me, I do not believe
> > it was even geared as a model for scales so small.
>
> What is your entirely plausible alternative explanation. I am dying to
> know ;-).
...that MOND is mapping out dark matter.
>
> > What folks seem to be missing is that success ofMONDand success of
> > dark matter are not mutually contradictory goals.MONDseems to lend
> > itself fairly easily to a dark matter explanation, despite how angry
> > that probably makes theMONDcrew.
>
> On the contrary, MOND is expected to make a lot of Relativists very
> angry when they find that no DM model can work ;-).
*points to weak lensing*
That is what it is all coming back to - weak lensing. Why does weak
lensing keep showing a distribution of dark matter if it isn't there?
>
> >
> > The constant inclusion of the virial mass [200x universe critical
> > density] and the size associated with it amuses me for some odd
> > reason...I don't find anything wrong or objectionable, it just amuses
> > me.
> >
> > > I don't know what you mean exactly by "suitable definitions of
> > > working", butMONDworks very well without any exceptions on the
> > > scale of galaxies. In 80% of galaxies it gives very good fits,
> > > for the rest of the 20%, it is known that there are problems with
> > > the data. And the important thing is that it cannot fit those 20%,
> > > as would be expected for a theory with no free parameters, a0 is
> > > no longer free. Another important thing is that DM models can fit
> > > those 20% cases also to the same degree of accuracy as the other
> > > 80%, because of the large number of free parameters.
> >
> > The number of free parameters isn't that big and you know it, if you
> > have actually been reading the papers you have been citing me.
>
> Even 2 free parameters are too many when a competing theory can fit
> the data without any free parameter. And most DM theories require 3 or
> 4 parameters. Remember that DM theories can fit the 20% cases where
> the data is problematic. This indicates that the free parameters are
> enough to fit any rotation curve even if they are not from a real
> galaxy. This is what proves that there are too many parameters. Any
> good model is one which is not able to work with bad data. DM models
> are not good models.
What happens when the competing theory fails in an unambigious way in
a different case?
I don't think DM is anywhere near the point to where one could say "So
what? I can fit any arbitrary curve with a large enough amount of
parameters!"
>
> > > The onus is on theoretical physicists to find the underlying reason.
> > > IgnoringMONDdoes not help.
> >
> > That much is now obvious.MONDis an excellent model for individual
> > galaxies, though I _suspect_ it fails for galaxies that are products
> > of or are in various stages of collision [eg, bullet cluster].
> >
> > Keep in mind that nothing you have shown me or what I have found
> > conclusively, or even most likely, makes dark matter an incorrect
> > model. In fact, everything I have seen thus far either supports or
> > refines dark matter. Using theMONDfits along with the empirical data
> > gives some nice constraints on entirely plausible distributions of
> > dark mater where there were none before, which is quite useful.
>
> I and possibly all of the MOND proponents are dying to know an
> entirely plausible distribution of DM that can fit MOND.
Read the papers I cited you previously. You will see where I'm coming
from.
Especially http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
anan...@gmail.com
> anan...@gmail.com wrote:
> >
> >
> > On Mar 20, 1:34 pm, "Eric Gisse" <jowr...@gmail.com> wrote:
> > > anands...@gmail.com wrote:
> There is _no_ reason to doubt that our interpretation of the weak
> lensing results is false. There is matter there and it curves light
> and we detect it. That is remarkably direct compared to other
> cosmological observations that are *heavily* model-dependent.
Just remember that I am arguing that there is no DM within Galaxy
scales. ie MOND explains Galaxy rotation curves so obviously
Weak Lensing will need to be explained by a quantum theory that
will derive MOND. In my GR+DM cannot explain MOND.
> > Neutrinos avoid this problem by being hot, which prevents their
> > coupling together.
>
> Neutrinos avoid the problem by having an insanely small scattering
> cross section and by traveling within epsilon of light speed for
> pretty much any plausible amount of energy. They avoid the problem so
> well that they are horrible dark matter candidates - not enough of
> them can be produced, and they are not capable of binding to galaxies
> considering how fast they would be traveling. Neutrino dark matter
> would form a background, not a halo.
True for Galaxy scales but not true for Cluster scales.
So whats your point?
> KATRIN isn't and never will be a test of MOND. Neutrino oscillations
> simply shift the flavors around - they do not add mass. Neutrino mass
> is constrained to be very tiny, and if the L-CDM model is even close
> to being reasonable the total masses of all neutrinos is less than an
> eV.
I don't understand this, the three flavours are supposed to have
weight
less than 2.2eV, 170KeV, and 15.5MeV. So even the lightest may be
heavier than 1eV. The others are much much more heavy.
Do you mean to say that KATRIN will falsify LCDM if electron neutrino
happens to have a weight more than 1eV. I don't believe that DM
theories are falsifiable. They are just curve fitting exercises. Add
as
much DM as you need whereever you need. LCDM theories need not
apply to Galactic level and the NFW halos need not have any
cosmological significance.
> No! Neutrinos _can not do it_!
You mean that Neutrinos cannot make stable structures at Cluster
sizes.
This is as much an speculation as is my assertion as mine. We don't
yet know the masses and relative abundance of the three neutrinos.
>
> Look back at that paper I linked to you the other day - remember how
> everything was consistent with a HALO of dark matter? There are simply
> not enough neutrinos and the ones whizzing around simply have too much
> energy to be bound.
>
> http://www.astro.ucla.edu/~wright/BBNS.html
>
It doesn't give any neutrino abundance. I would think that there may
be
a huge amount of neutrino as it is a very important part of the
reactions
below one second timeframe. Also I do not expect that all of it will
be
absorbed. It is entirely plausible to have a large amount of
neutrinos.
>
> Both DM and MOND were hypotheses created to explain galactic rotation
> curves. MOND, however, can't handle the large scale structure of the
> universe while DM is an fundamental part in something that makes a
> very, very good fit. Remember what you told me - something that fits
> that well has to have some fashion of truth to it?
So give me one DM theory that works well at the large structure and
works well for the galaxies as well. We know that LCDM does not work
well at Galaxy level.
There is a difference between MOND and DM.
DM is a curve fitting exercise requiring the use of several free
parameters,
while MOND is a single equation that works well with a single
universal
parameter on all galaxies.
> > TeVeS is making testable predictions. I personally don't like TeVeS,
> > but it is not a bad idea. We may come up with a law for weak lensing
> > through it. This work is also needed for convincing GR proponents that
> > DM in Galaxies is redundant.
>
> I wish them the best of luck - they have some severe hurdles to pass
> through.
>
> They have to describe *all* of the following self-consistently:
>
Well GR has to explain MOND. Unless it does so, it is a suspect
theory.
It needs to show how DM should be distributed to explain MOND.
It must show why it should have this distribution and not any other.
It must show why DM is required when the curves can be explained
based on only BM.
> 1) Make dark matter irrelevant.
Why???
Bullet Cluster shows that DM exists at the cluster scale, which was
already expected from previous MOND fits to other cluster.
You can change it to Make dark matter irrelevent at the galactic
scale.
It is certainly not required at the galactic scales.
I don't disagree with the rest of your list. They are certainly
required
by any quantum theory of gravity.
> > MOND/TeVeS works well in strong gravity, as they are basically same as
> > GR. Works very well in Galaxies. Predicts HDM in Clusters, as required
> > by Bullet Cluster. Also is not against Dark Galaxies. It can be
> > falsified, but has not been falsified yet.
>
> Careful when you say 'required'. I have been trying to distinguish
> between things that are observationally true and which are required to
> be true within a specific hypothesis.
>
> Hot neutrinos - it isn't something required by MOND, it is a
> *hypothesis* that is added in to explain the bullet cluster within the
> context of MOND.
It is *required* by MOND to fit Bullet Cluster or any Cluster data.
It may be that MOND is not the correct theory. But the Bullet Cluster
proves that there is dark matter at cluster scales.
> > There is no need to remove Dark Matter in Bullet Cluster. It is an
> > unambiguous observation that Dark Matter exists in Bullet Cluster.
>
> Zuh?
>
> Are folks folks going with the King Solomon approach and splitting the
> difference? Arguing both dark matter *AND* MOND is a little
> contradictory to me.
You have a lot of prejudice regarding MOND. I don't think I can rid
you
of your prejudice. You see the forest and cannot focus down to the
trees.
It is obvious that MOND and Dark Matter are not incompatible.
If you ask Milgrom himself, he will not agree with your statement.
The whole point of MOND is to show that a simple modification to
Newtons law can explain rotation curves of all galaxies. It doesn't
mean that we have seen everything, and that DM cannot exist in
clusters.
It only means that there is no need for DM in Galaxies. Nothing more
nothing less.
I don't think I can continue this discussion if you cannot grasp
this basic fact of MOND.
>
> > Also MOND has been predicting double the mass in most Clusters, which
> > should be the same Dark Matter which we see in Bullet Cluster. But
> > that doesn't mean that it has to be CDM, it could be HDM.
>
> ...and how many HDM candidates are there? There aren't that many
> stable particles which don't interact electromagnetically...
And how many CDM candidates have been observed.
At least Neutrino has been observed and has now been shown to
oscillate
with some flavours having huge masses. Since we don't know the
average
mass we cannot yet conclude that it cannot make stable structures
yet.
> > > Let me be clear - I accepted before and accept even more now thatMOND
> > > is pointing to something important. What we seem to disagree on is
> > > _what_ that important thing is.
> >
> > Well now I can rejoice ;-). We have reached the most important part of
> > the discussion. You accept MOND effect as real.
>
> Yes and no.
>
> I accept that MOND is an accurate model over a surprisingly large
> sample set. I rationalize it thusly: all galaxies appear to have
> formed in the same way, more or less. So it stands to reason that DM
> will be the same in each galaxy [less collisions and exotic
> circumstances] if not more so due to the lack of interaction.
>
> I do not accept that MOND is a physical theory unto itself. There are
> too many results from weak lensing that make dark matter convincing in
> my eye, as well as its' utility in cosmological modeling. The MOND
> folkes probably would _not_ like that position.
Again the forest. Try to focus only on one aspect at one time. Looking
at trees only sometimes is useful.
It is obvious that MOND is not a physical theory. It is just a visible
artifact of the Quantum Theory of Gravity.
We know that Weak Lensing and Rotation Curves must have the same
origin. If it is GR+BM+DM then it is the same for both if it is QTG+BM
then it will be the same for both. Now if we can prove that GR+BM+DM
cannot fit the Rotation Curves as well or better than MOND, then we
have proved that GR+BM+DM is not the correct picture. And we must
look into finding a theory QTG that is compatible with MOND and also
explains weak lensing based only on BM.
The real solution is only to find a distribution of DM that has the
following
properties.
1) It can fit MOND at the currect epoch.
2) It can fit WMAP using a distribution that should be able to reach
the
MONDian distribution at the current epoch.
3) There must be some observable departures from MOND which we
can see to discard MOND. In other words there can be no DM theory
that will be indistinguishable from MOND, because DM cannot have
zero degrees of freedom.
> > 2) We cannot be living in a special epoch, when DM matches MOND
> > everywhere. It must have been true for a very long time in the past.
> > And will
> > continue to do so for a very long time in the future.
>
> I don't see why not - at least, the matching part. I am yet to hear a
> convincing explanation as to why MOND *can't* be represenative of dark
> matter.
We cannot be living in a special epoch because the galaxies we see are
in different stages of development. DM cannot fit MOND for all of them
unless it fits all of them at all times. So there can be no special
epoch.
I thought it was obvious so did not give my reasoning.
> > 4) If you see the 3 points above you see that DM in galaxies is
> > superfluous. It must satisfy too many features to be true, and top of
> > that it has no degrees of freedom, which makes it a superflous
> > concept. This is where Occam's Razor steps in to say that DM is not
> > simpler than MOND, and so must not be the true picture of the world.
>
> I don't think you are applying Occam's razor properly. DM as a concept
> is quite simple - there is matter we can't see that explains otherwise
> contradictory observations. The concept is not superfluous because
> there is no alternative _physical_ explanation, nor is there an
> explanation of lensing results.
I think you are not applying it properly.
DM is simple but DM mimicking MOND is not. MOND is the real crux of
the problem. Without MOND, there is no trouble for DM at all.
With MOND it becomes totally superfluous (Just to remind only at the
galaxy level, MOND doesn't fit Cluster data, so DM is not superfluous
there).
DM is a simple concept.
MOND is a more complex concept.
DM mimicking MOND is a very complex concept.
> > On the contrary, MOND is expected to make a lot of Relativists very
> > angry when they find that no DM model can work ;-).
>
> *points to weak lensing*
>
> That is what it is all coming back to - weak lensing. Why does weak
> lensing keep showing a distribution of dark matter if it isn't there?
Weak Lensing is irrevelent, and I am not ignoring it while saying
that.
> > Even 2 free parameters are too many when a competing theory can fit
> > the data without any free parameter. And most DM theories require 3 or
> > 4 parameters. Remember that DM theories can fit the 20% cases where
> > the data is problematic. This indicates that the free parameters are
> > enough to fit any rotation curve even if they are not from a real
> > galaxy. This is what proves that there are too many parameters. Any
> > good model is one which is not able to work with bad data. DM models
> > are not good models.
>
> What happens when the competing theory fails in an unambigious way in
> a different case?
>
> I don't think DM is anywhere near the point to where one could say "So
> what? I can fit any arbitrary curve with a large enough amount of
> parameters!"
Actually it is at that stage. I had seen somewhere can't remember
whether
it was a paper or article, in which they had created a pseudo galaxy
by merging data of two real galaxies. MOND would not fit that data,
while LCDM halos where able to fit it.
> > I and possibly all of the MOND proponents are dying to know an
> > entirely plausible distribution of DM that can fit MOND.
>
> Read the papers I cited you previously. You will see where I'm coming
> from.
>
> Especially http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
Which one do you mean?
PseudoIsothermal Halo or NFW Halo.
I don't think there is any large scale formation theory for either of
them.
The most popular theory that explains large scale structure formation
is LCDM which fails badly on most Galaxies.
You must understand that any distribution must have a valid formation
theory behind it. One is not complete without the other.
Eric Gisse
> Eric Gisse wrote:
> > anan...@gmail.com wrote:
> > >
> > >
> > > On Mar 20, 1:34 pm, "Eric Gisse" <jowr...@gmail.com> wrote:
> > > > anands...@gmail.com wrote:
> > There is _no_ reason to doubt that our interpretation of the weak
> > lensing results is false. There is matter there and it curves light
> > and we detect it. That is remarkably direct compared to other
> > cosmological observations that are *heavily* model-dependent.
>
> Just remember that I am arguing that there is no DM within Galaxy
> scales. ie MOND explains Galaxy rotation curves so obviously
> Weak Lensing will need to be explained by a quantum theory that
> will derive MOND. In my GR+DM cannot explain MOND.
Galactic/cluster scales are deeply classical - there is no reason to
expect a quantum theory would make any modifications at such
macroscopic distances. What we got is what we got, any modifications
to what we already know at large scales would have to be very subtle.
You can argue that there is no DM within a galaxy, but you can't argue
it from observational evidence. I can't argue against it, from the
same token - but I would think it odd that it all accumulates in the
halo.
>
> > > Neutrinos avoid this problem by being hot, which prevents their
> > > coupling together.
> >
> > Neutrinos avoid the problem by having an insanely small scattering
> > cross section and by traveling within epsilon of light speed for
> > pretty much any plausible amount of energy. They avoid the problem so
> > well that they are horrible dark matter candidates - not enough of
> > them can be produced, and they are not capable of binding to galaxies
> > considering how fast they would be traveling. Neutrino dark matter
> > would form a background, not a halo.
>
> True for Galaxy scales but not true for Cluster scales.
> So whats your point?
What's another order of magnitude going to do?
Look, neutrinos travel _FAST_ - within an epsilon of c for all
realistic kinetic energies obtained from fusion reactions at the big
bang. There simply aren't any bound orbits - the best you can
reasonably expect is a weak background, which isn't going to influence
anything significantly.
>
> > KATRIN isn't and never will be a test of MOND. Neutrino oscillations
> > simply shift the flavors around - they do not add mass. Neutrino mass
> > is constrained to be very tiny, and if the L-CDM model is even close
> > to being reasonable the total masses of all neutrinos is less than an
> > eV.
>
> I don't understand this, the three flavours are supposed to have
> weight
mass =/= weight.
> less than 2.2eV, 170KeV, and 15.5MeV. So even the lightest may be
> heavier than 1eV. The others are much much more heavy.
No - those are the _least_ upper bounds on individual neutrino
masses. The individual measurements are gross measurements to say the
least - the spread is huge. However, the sum of neutrino masses is
quite small - on the order of an eV, as constrained by astrophysical
results [model dependent, but the consistency is very good across
varying data sets].
http://pdg.lbl.gov/2006/listings/s066.pdf
> Do you mean to say that KATRIN will falsify LCDM if electron neutrino
> happens to have a weight more than 1eV. I don't believe that DM
> theories are falsifiable. They are just curve fitting exercises. Add
> as
> much DM as you need whereever you need. LCDM theories need not
> apply to Galactic level and the NFW halos need not have any
> cosmological significance.
If neutrino masses were observed directly to be far larger than a
fraction of an eV, I think it would be troublesome. But how exactly it
would be troublesome is less than clear to me.
Until some actual viable candidates are put forth, DM will be a bit
less than strong in its' foundation. However, something that preserves
our current theories of gravity and whose inclusion is supported by
modeling of the large scale structure of the universe is quite
compelling, especially when the only theory that is remotely competing
at this point is an even more ad-hoc theory.
Do not forget the supreme irony of neutrinos being anyway important in
finding dark matter. Neutrinos were postulated a full 25 years or so
before they were detected to explain the spectrum of energies in beta
decay and to explain why angular momentum was not conserved.
>
> > No! Neutrinos _can not do it_!
>
> You mean that Neutrinos cannot make stable structures at Cluster
> sizes.
> This is as much an speculation as is my assertion as mine. We don't
> yet know the masses and relative abundance of the three neutrinos.
Relative abundances can be gathered via big bang nucleosynthesis. I
gave you a link ...somewhere... that listed the top 10 or so most
common reactions, and neutrinos were in most of them.
It does not matter - the energies given to the neutrinos will be in
the MeV range. That is DEEPLY relativistic - E ~ pc for E >> mc^2.
Work backwards - how many zeros will be in your answer when you obtain
1 - v/c?
Borrowing from GR slightly, neutrinos are the massive equivalent of
light. They are the closest a massive particle can get to traveling on
a geodesic. Borrowing further, light only has closed [UNSTABLE!]
orbits around a mass when it is near [r ~ GM] the Schwarzschild
radius. Dark matter is out in the halos of galaxies and such - a shade
short.
>
> >
> > Look back at that paper I linked to you the other day - remember how
> > everything was consistent with a HALO of dark matter? There are simply
> > not enough neutrinos and the ones whizzing around simply have too much
> > energy to be bound.
> >
> > http://www.astro.ucla.edu/~wright/BBNS.html
> >
Oh look there it is.
>
> It doesn't give any neutrino abundance. I would think that there may
> be
> a huge amount of neutrino as it is a very important part of the
> reactions
> below one second timeframe. Also I do not expect that all of it will
> be
> absorbed. It is entirely plausible to have a large amount of
> neutrinos.
Of course there will be a large number of neutrinos. They will for all
intents and purposes still be tooling around, barring ridiculously
rare absorbtion events.
They are very, very light and they are moving very, very fast. They do
not matter - neutrino-based dark matter has been long discredited even
before weak lensing results started coming in.
>
> >
> > Both DM and MOND were hypotheses created to explain galactic rotation
> > curves. MOND, however, can't handle the large scale structure of the
> > universe while DM is an fundamental part in something that makes a
> > very, very good fit. Remember what you told me - something that fits
> > that well has to have some fashion of truth to it?
>
> So give me one DM theory that works well at the large structure and
> works well for the galaxies as well. We know that LCDM does not work
> well at Galaxy level.
We don't have one as far as I know.
However, MOND seems like a good start. But I think Milgrom et al's
head would explode if the dark matter people co-opted MOND in that
fashion.
>
> There is a difference between MOND and DM.
> DM is a curve fitting exercise requiring the use of several free
> parameters,
> while MOND is a single equation that works well with a single
> universal
> parameter on all galaxies.
No.
If you read the papers I linked you, there is a direct correspondence
between dark matter and baryonic matter. The amount of free parameters
got very, very small.
>
> > > TeVeS is making testable predictions. I personally don't like TeVeS,
> > > but it is not a bad idea. We may come up with a law for weak lensing
> > > through it. This work is also needed for convincing GR proponents that
> > > DM in Galaxies is redundant.
> >
> > I wish them the best of luck - they have some severe hurdles to pass
> > through.
> >
> > They have to describe *all* of the following self-consistently:
> >
>
> Well GR has to explain MOND. Unless it does so, it is a suspect
> theory.
G_uv = 8piG/c^2 T_uv
That is GR right there. Everything GR predicts is based upon what you
shove into T_uv - what do you suggest? Besides, the full machinery of
GR is un-needed. Newton works for this - deeply classical, remember?
GR is basically a few extra decimal places at 100AU distance - much
less hundreds of thousands of light years.
> It needs to show how DM should be distributed to explain MOND.
This has been done by working backwards from the observed
distributions and Poisson's equation. MOND and DM play nice together.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
Seriously - did you read this?
> It must show why it should have this distribution and not any other.
> It must show why DM is required when the curves can be explained
> based on only BM.
No, it doesn't. The question of "why" is not science's problem. The
best you can hope for is "how?"
>
> > 1) Make dark matter irrelevant.
> Why???
Making dark matter irrelevant is MOND's reason d'etre, that's why.
> Bullet Cluster shows that DM exists at the cluster scale, which was
> already expected from previous MOND fits to other cluster.
> You can change it to Make dark matter irrelevent at the galactic
> scale.
> It is certainly not required at the galactic scales.
Bullshit it hasn't.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
>
> I don't disagree with the rest of your list. They are certainly
> required
> by any quantum theory of gravity.
I'm not talking about a quantum theory specifically - I'm talking
about anything that seeks to supplant GR. The list is geared more
towards TeVeS and such.
>
>
> > > MOND/TeVeS works well in strong gravity, as they are basically same as
> > > GR. Works very well in Galaxies. Predicts HDM in Clusters, as required
> > > by Bullet Cluster. Also is not against Dark Galaxies. It can be
> > > falsified, but has not been falsified yet.
> >
> > Careful when you say 'required'. I have been trying to distinguish
> > between things that are observationally true and which are required to
> > be true within a specific hypothesis.
> >
> > Hot neutrinos - it isn't something required by MOND, it is a
> > *hypothesis* that is added in to explain the bullet cluster within the
> > context of MOND.
>
> It is *required* by MOND to fit Bullet Cluster or any Cluster data.
> It may be that MOND is not the correct theory. But the Bullet Cluster
> proves that there is dark matter at cluster scales.
>
> > > There is no need to remove Dark Matter in Bullet Cluster. It is an
> > > unambiguous observation that Dark Matter exists in Bullet Cluster.
> >
> > Zuh?
> >
> > Are folks folks going with the King Solomon approach and splitting the
> > difference? Arguing both dark matter *AND* MOND is a little
> > contradictory to me.
>
> You have a lot of prejudice regarding MOND. I don't think I can rid
> you
> of your prejudice. You see the forest and cannot focus down to the
> trees.
Of course I am prejudiced. The proponents of MOND seem to think it is
a theory of gravity unto itself rather than a model.
> It is obvious that MOND and Dark Matter are not incompatible.
> If you ask Milgrom himself, he will not agree with your statement.
> The whole point of MOND is to show that a simple modification to
> Newtons law can explain rotation curves of all galaxies. It doesn't
> mean that we have seen everything, and that DM cannot exist in
> clusters.
...then when a fair bit of evidence crops up which shows that it is an
actual matter distribution causing the funky rotation curves?
>
> It only means that there is no need for DM in Galaxies. Nothing more
> nothing less.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
READ IT
>
> I don't think I can continue this discussion if you cannot grasp
> this basic fact of MOND.
>
> >
> > > Also MOND has been predicting double the mass in most Clusters, which
> > > should be the same Dark Matter which we see in Bullet Cluster. But
> > > that doesn't mean that it has to be CDM, it could be HDM.
> >
> > ...and how many HDM candidates are there? There aren't that many
> > stable particles which don't interact electromagnetically...
>
> And how many CDM candidates have been observed.
Viable? Zero.
> At least Neutrino has been observed and has now been shown to
> oscillate
> with some flavours having huge masses. Since we don't know the
> average
> mass we cannot yet conclude that it cannot make stable structures
> yet.
1 is less than 1 trillion. If my least upper bound is 1 trillion, 1 is
the possible true value.
Read the PDG link I gave you. The sum of masses appears to be less
than an eV.
>
> > > > Let me be clear - I accepted before and accept even more now thatMOND
> > > > is pointing to something important. What we seem to disagree on is
> > > > _what_ that important thing is.
> > >
> > > Well now I can rejoice ;-). We have reached the most important part of
> > > the discussion. You accept MOND effect as real.
> >
> > Yes and no.
> >
> > I accept that MOND is an accurate model over a surprisingly large
> > sample set. I rationalize it thusly: all galaxies appear to have
> > formed in the same way, more or less. So it stands to reason that DM
> > will be the same in each galaxy [less collisions and exotic
> > circumstances] if not more so due to the lack of interaction.
> >
> > I do not accept that MOND is a physical theory unto itself. There are
> > too many results from weak lensing that make dark matter convincing in
> > my eye, as well as its' utility in cosmological modeling. The MOND
> > folkes probably would _not_ like that position.
>
> Again the forest. Try to focus only on one aspect at one time. Looking
> at trees only sometimes is useful.
>
> It is obvious that MOND is not a physical theory. It is just a visible
> artifact of the Quantum Theory of Gravity.
No. It isn't.
MOND was designed to, and continues to be, an exercise in curve
fitting that has served its' purpose very well. Getting the answer
right in one _limited_ regime does _not_ make it a viable theory of
gravity.
>
> We know that Weak Lensing and Rotation Curves must have the same
> origin. If it is GR+BM+DM then it is the same for both if it is QTG+BM
> then it will be the same for both. Now if we can prove that GR+BM+DM
> cannot fit the Rotation Curves as well or better than MOND, then we
> have proved that GR+BM+DM is not the correct picture. And we must
> look into finding a theory QTG that is compatible with MOND and also
> explains weak lensing based only on BM.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
Dark matter and MOND share a large degree of correspondence. You
seriously need to read that paper.
>
> The real solution is only to find a distribution of DM that has the
> following
> properties.
> 1) It can fit MOND at the currect epoch.
> 2) It can fit WMAP using a distribution that should be able to reach
> the
> MONDian distribution at the current epoch.
WMAP data is an observation of the background radiation - it is about
14 billion years short.
> 3) There must be some observable departures from MOND which we
> can see to discard MOND. In other words there can be no DM theory
> that will be indistinguishable from MOND, because DM cannot have
> zero degrees of freedom.
The bullet cluster is already an observable departure. You can't be
choosy and suddenly make MOND applicable only to galactic scales when
the entire theory is based around modifying gravity for low
accelerations.
>
> > > 2) We cannot be living in a special epoch, when DM matches MOND
> > > everywhere. It must have been true for a very long time in the past.
> > > And will
> > > continue to do so for a very long time in the future.
> >
> > I don't see why not - at least, the matching part. I am yet to hear a
> > convincing explanation as to why MOND *can't* be represenative of dark
> > matter.
>
> We cannot be living in a special epoch because the galaxies we see are
> in different stages of development. DM cannot fit MOND for all of them
> unless it fits all of them at all times. So there can be no special
> epoch.
They are not different.
Barring exceptional cases and galaxies that have suffered collisions,
they are all the same up to a parameter or three.
>
> I thought it was obvious so did not give my reasoning.
>
> > > 4) If you see the 3 points above you see that DM in galaxies is
> > > superfluous. It must satisfy too many features to be true, and top of
> > > that it has no degrees of freedom, which makes it a superflous
> > > concept. This is where Occam's Razor steps in to say that DM is not
> > > simpler than MOND, and so must not be the true picture of the world.
> >
> > I don't think you are applying Occam's razor properly. DM as a concept
> > is quite simple - there is matter we can't see that explains otherwise
> > contradictory observations. The concept is not superfluous because
> > there is no alternative _physical_ explanation, nor is there an
> > explanation of lensing results.
>
> I think you are not applying it properly.
>
> DM is simple but DM mimicking MOND is not. MOND is the real crux of
> the problem. Without MOND, there is no trouble for DM at all.
> With MOND it becomes totally superfluous (Just to remind only at the
> galaxy level, MOND doesn't fit Cluster data, so DM is not superfluous
> there).
>
> DM is a simple concept.
> MOND is a more complex concept.
> DM mimicking MOND is a very complex concept.
http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
READ IT
So how does that support your assertion that it has too many
parameters? The L-CDM model has a _highly constrained_ 6 dimensional
parameter space. I have linked you to the WMAP site and specific
papers before - the amount of freedom the parameters have are quite
small.
Do you know how many parameters I need to do a QM problem? Same order
of magnitude.
>
> > > I and possibly all of the MOND proponents are dying to know an
> > > entirely plausible distribution of DM that can fit MOND.
> >
> > Read the papers I cited you previously. You will see where I'm coming
> > from.
> >
> > Especially http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/58610.html
>
> Which one do you mean?
> PseudoIsothermal Halo or NFW Halo.
Whichever.
>
> I don't think there is any large scale formation theory for either of
> them.
>
> The most popular theory that explains large scale structure formation
> is LCDM which fails badly on most Galaxies.
Does it...?
Reference?
>
> You must understand that any distribution must have a valid formation
> theory behind it. One is not complete without the other.
Interesting how dark matter is held up to the standard of "explain
anything and everything" [as it should] whereas MOND gets the "eh it
works sometimes - must be true" treatment.
anan...@gmail.com
> > > anands...@gmail.com wrote:
> > It needs to show how DM should be distributed to explainMOND.
>
> This has been done by working backwards from the observed
>
> http://www.journals.uchicago.edu/ApJ/journal/issues/ApJ/v609n2/58610/...
>
> Seriously - did you read this?
And Seriously did you??
You think that MOND and DM play nice. But the author of the paper
doesn't think so. So how did you come to that conclusion from this
paper.
There can only be one of two options at the galactic scale.
1) There is a difference between MOND and GR+DM. In this case we
know that MOND works better than GR+DM for all theories of GR+DM.
So obviously MOND is the correct law.
2) There is no difference between MOND and GR+DM, in which case
DM does not exist and MOND is wrong. Because there can be no
matter that has no degrees of freedom.
If you think that a kind of matter can exist without any degrees
of freedom. You are entitled to your opinion, but it is not a
scientific opinion.
There are only two realistic options.
1) You can ignore MOND, and believe that MOND proponents are
crackpots.
2) You have to accept MOND, and the failure of GR.
There is no middle way. GR+DM cannot model MOND.
I think we are at a stalemate. There is no point in arguing further.
regards,
-anandsr