MOND explains the rotation curves of galaxies extremely well; Dark Matter explains the same things not so well. Dark Matter explains galactic cluster interactions extremely well; MOND explains the same things not so well. That's the long and short of it.
/Dark Fields/ is an attempt to make MOND work better at the cluster level. There is a lot of cajoling needed to make Dark Matter work well within the galactic scale too. So it looks like neither theory works well outside their on size scale.
SPACE.com -- Dark Horse Challenges Dark Matter to Explain Missing Matter "When applied to just galaxies, MOND can predict very well the behavior that astronomers observe. But when MOND is applied to larger structures like clusters of galaxies, it fails. To make MOND work for clusters, it must include more complicated concepts, such as entities called dark fields, which are different from dark matter, but work in a similar way to alter the amount of gravity present." http://www.space.com/scienceastronomy/091105-missing-matter.html
Unmodified Newtonian Dynamics includes Newton's corpuscles of light which obey Newton's laws, not Einstein's. What you need is MORE - modified relativity of Einstein.
> MOND explains the rotation curves of galaxies extremely well; Dark > Matter explains the same things not so well. Dark Matter explains > galactic cluster interactions extremely well; MOND explains the same > things not so well. That's the long and short of it.
> /Dark Fields/ is an attempt to make MOND work better at the cluster > level. There is a lot of cajoling needed to make Dark Matter work well > within the galactic scale too. So it looks like neither theory works > well outside their on size scale.
> SPACE.com -- Dark Horse Challenges Dark Matter to Explain Missing Matter > "When applied to just galaxies, MOND can predict very well the behavior > that astronomers observe. But when MOND is applied to larger structures > like clusters of galaxies, it fails. To make MOND work for clusters, it > must include more complicated concepts, such as entities called dark > fields, which are different from dark matter, but work in a similar way > to alter the amount of gravity present." > http://www.space.com/scienceastronomy/091105-missing-matter.html
> Yousuf Khan
Now, if you look at a an insect climbing up a wall defying gravity, it would be impossible to understand without realizing that for an insect, a set of forces (intermolecular attraction) applies that for a human climber doing the Everest do not apply at all.
What about this at all scales?
There could be at bigger scales than the galactic scale forces that appear that are completely unknown and unobservable at smaller scales.
Galaxy clusters seem to appear at the intersection of galaxy "rivers" that flow around the "skeleton" of the universe. It could be that this "skeleton" produces forces that are unknown to us.
Forces that would apply to galaxies, but not within galaxies.
And obviously this skeleton would apply at galaxy cluster scale. In bigger scales than those, yet ANOTHER forces would apply.
Yousuf Khan wrote: > MOND explains the rotation curves of galaxies extremely well;
Ballmer explains the spectrum of the Hydrogen atom really well too.
> Dark Matter explains the same things not so well.
No.
> Dark Matter explains > galactic cluster interactions extremely well; MOND explains the same > things not so well. That's the long and short of it.
MOND has extreme difficulties with anything but rotation curves.
> /Dark Fields/ is an attempt to make MOND work better at the cluster > level.
There are two ponderous concepts at work here.
i) MOND has an entirely arbitrary interpolation function that has no real world constraints on it, and that still isn't good enough. ii) MOND proponents feel that dark matter (and presumably, energy) are unphysical or wrong for some personal reason but still feel that MOND and its' extensions which use increasingly larger amounts of arbitrary sourceless fields is a more intuitive / understandable / correct model.
> There is a lot of cajoling needed to make Dark Matter work well > within the galactic scale too. So it looks like neither theory works > well outside their on size scale.
Except dark matter works well enough on the galactic scale. What it has difficulties amount to fine tuning issues which just might be related to our ignorance of galactic structures and oversimplified models.
> SPACE.com -- Dark Horse Challenges Dark Matter to Explain Missing Matter > "When applied to just galaxies, MOND can predict very well the behavior > that astronomers observe. But when MOND is applied to larger structures > like clusters of galaxies, it fails. To make MOND work for clusters, it > must include more complicated concepts, such as entities called dark > fields, which are different from dark matter, but work in a similar way > to alter the amount of gravity present."
*laughs*
Oh yes, dark FIELDS. That's entirely more acceptable than dark MATTER. I'm sure that theory will hit the ground /running/.
I believe dark matter's science has cold technology base of supernova explosions. No, I am not saying they came from supernova explosions, but one finds the ice skating balerina in contracting or expanding gravitating balls, where energies can build while the contracting ball spins up. Inverted processes are found in the fields of energy in disk sciences.
Einstein left the puzzle of rotating disks unsolved in his theory of relativity.
It brings anti-gravity studies, and cold alien technologies, even building real gravity fields with electromagnetic spin of balls, one gram reduction of mass for a saucer, meaning it can zig zag and move around like a feather very easily from one end of the sky to the other in fractions of a second. All alien technologies in the end, but even a real holodeck that works outdoors built from it. Totalitarian "alien" technologies that are as much as 5000 years more advanced.
If you weigh one gram, you punch someone and have no effect, and your arms and legs move instantly back and forth without inertia. People can fight with unprecedented speed of arm and leg motion and feel no pain.
> I believe dark matter's science has cold technology base of supernova > explosions. No, I am not saying they came from supernova explosions, > but one finds the ice skating balerina in contracting or expanding > gravitating balls, where energies can build while the contracting ball > spins up. Inverted processes are found in the fields of energy in disk > sciences.
> Einstein left the puzzle of rotating disks unsolved in his theory of > relativity.
> It brings anti-gravity studies, and cold alien technologies, even > building real gravity fields with electromagnetic spin of balls, one > gram reduction of mass for a saucer, meaning it can zig zag and move > around like a feather very easily from one end of the sky to the other > in fractions of a second. All alien technologies in the end, but even > a real holodeck that works outdoors built from it. Totalitarian > "alien" technologies that are as much as 5000 years more advanced.
> If you weigh one gram, you punch someone and have no effect, and your > arms and legs move instantly back and forth without inertia. People > can fight with unprecedented speed of arm and leg motion and feel no > pain.
One gram punch of energy. Keep adding up the gravitational energy.
On Nov 6, 1:18 am, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote:
> MOND ... > Dark Matter ... > /Dark Fields/ ...
Maybe you have lost sight of the big picture. MOND uses the visible matter and its "geometry" to make rotation curves work, but it does not cover microlensing.
Dark Matter suspends any other scientific theory-set, for a substance that can be arbitrarily located to make measurements work, a substance that only "hooks" into this Universe as mass... no other properties. There are a host of proposed particles that are being searched for that are close to Dark Matter, but they will have some 'spainin to do as to how we see what we see in the Universe displayed.
Dark Fluid has *no* properties that are substantially improved over Dark Matter. It *must* substantially decay into the definition of Dark Matter in the final analysis. It can have no properties associated with a fluid (say viscosity, or pressure), or it violates what we see.
You are sniffing up any skirt that seems to offer an alternative to Dark Matter. And I am telling you, Dark Fluid ain't it.
Now what I'd like to propose is, if inertia derives from all the mass in the Universe (ala Mach), and the speed of *this* effect (establishment of inertia) is large-but-finite, what if Dark Matter is simply "echos" of an effect of the event horizons (say) that spent time in any given bit of space? Expansion also looks like everything shrinking in place (due to increasing clock rates). I mean if we are sky-balling...
dlzc wrote: > Dark Fluid has *no* properties that are substantially improved over > Dark Matter. It *must* substantially decay into the definition of > Dark Matter in the final analysis. It can have no properties > associated with a fluid (say viscosity, or pressure), or it violates > what we see.
Well, this article isn't talking about "Dark Fluid" but "Dark Fields". Different theories, though I don't know what the explanation of Dark Fields are supposed to be yet. The only explanation is that it is an extension of MOND to account for cluster deficiencies.
But getting back to Dark Fluid, why do you say it violates what we see? Dark Fluid is supposed to be a complete alternative to MOND, Dark Matter and Dark Energy, so the fact that it "decays" into something similar to Dark Matter is exactly what it was supposed to do at some particular scale. Dark Energy is a repulsive force, Dark Matter an attractive force, both acting on the same medium albeit at different scales. Those would indicate fluidic behaviour.
> You are sniffing up any skirt that seems to offer an alternative to > Dark Matter. And I am telling you, Dark Fluid ain't it.
Just presenting the latest news.
> Now what I'd like to propose is, if inertia derives from all the mass > in the Universe (ala Mach), and the speed of *this* effect > (establishment of inertia) is large-but-finite, what if Dark Matter is > simply "echos" of an effect of the event horizons (say) that spent > time in any given bit of space? Expansion also looks like everything > shrinking in place (due to increasing clock rates). I mean if we are > sky-balling...
For that matter, we could even theorize that Dark Matter and Dark Energy is just standard gravity's symmetry breaking as the Universe cools toward absolute zero, turning into two different forces: a super-gravity and an anti-gravity.
Yousuf Khan wrote: > MOND explains the rotation curves of galaxies extremely well; Dark > Matter explains the same things not so well. Dark Matter explains > galactic cluster interactions extremely well; MOND explains the same > things not so well. That's the long and short of it.
22 Oct 2002 - The Chandra X-ray Observatory presented evidence against the modifications of Newtonian Dynamics (MOND) alternative to dark matter theories. The August 2002 Scientific American has a long article about MOND. The hot X-ray emitting gas around the galaxy NGC 720 forms an ellipsoidal cloud, which requires an ellipsoidal gravitational potential well. While an ellipsoidal cloud of dark matter could provide such a well, MOND would necessarily give a spherical potential well. In general MOND works well on the scale of individual galaxies, but not for clusters of galaxies. So why is MOND only maybe dead? Its supporters like Milgrom are persistent and clever, and they may come up with a MONDian explanation for NGC 720.
21 Aug 2006 - NASA announced updated information about the "bullet cluster" 1E0657-56 today. Two clusters of galaxies have recently collided in this X-ray source. This cluster is filled with hot gas so X-ray observations by the Chandra X-ray Observatory show where the ordinary matter is located. 90% of the ordinary matter (the "baryonic" matter) is hot gas.
The new results [Clowe et al., Bradac et al.] use gravitational lensing of background galaxies to show where the sources of gravity are located. The sources of gravity in the cluster are not located where the ordinary matter is located, so this cluster is a counter-example to MOND. All of this was known in 2003 but with less precision. Sean Carroll has a nice post about this at Cosmic Variance.
Explanation: The matter in galaxy cluster 1E 0657-56, fondly known as the "bullet cluster", is shown in this composite image. A mere 3.4 billion light-years away, the bullet cluster's individual galaxies are seen in the optical image data, but their total mass adds up to far less than the mass of the cluster's two clouds of hot x-ray emitting gas shown in red. Representing even more mass than the optical galaxies and x-ray gas combined, the blue hues show the distribution of dark matter in the cluster. Otherwise invisible to telescopic views, the dark matter was mapped by observations of gravitational lensing of background galaxies.
In a text book example of a shock front, the bullet-shaped cloud of gas at the right was distorted during the titanic collision between two galaxy clusters that created the larger bullet cluster itself. But the dark matter present has not interacted with the cluster gas except by gravity. The clear separation of dark matter and gas clouds is considered direct evidence that dark matter exists.
> /Dark Fields/ is an attempt to make MOND work better at the cluster > level. There is a lot of cajoling needed to make Dark Matter work well > within the galactic scale too. So it looks like neither theory works > well outside their on size scale.
> SPACE.com -- Dark Horse Challenges Dark Matter to Explain Missing Matter > "When applied to just galaxies, MOND can predict very well the behavior > that astronomers observe. But when MOND is applied to larger structures > like clusters of galaxies, it fails. To make MOND work for clusters, it > must include more complicated concepts, such as entities called dark > fields, which are different from dark matter, but work in a similar way > to alter the amount of gravity present." > http://www.space.com/scienceastronomy/091105-missing-matter.html
On Nov 6, 3:26 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote:
> dlzc wrote: > > Dark Fluid has *no* properties that are substantially > > improved over Dark Matter. It *must* substantially > > decay into the definition of Dark Matter in the final > > analysis. It can have no properties associated with > > a fluid (say viscosity, or pressure), or it violates > > what we see.
> Well, this article isn't talking about "Dark Fluid" but > "Dark Fields". Different theories, though I don't know > what the explanation of Dark Fields are supposed to be > yet. The only explanation is that it is an extension of > MOND to account for cluster deficiencies.
It doesn't fix microlensing, so it is a patch to a flawed model.
> But getting back to Dark Fluid, why do you say it > violates what we see? Dark Fluid is supposed to be > a complete alternative to MOND, Dark Matter > and Dark Energy, so the fact that it "decays" into > something similar to Dark Matter is exactly what it > was supposed to do at some particular scale.
Then it is Dark Matter, and no solution.
> Dark Energy is a repulsive force, Dark Matter an > attractive force, both acting on the same medium > albeit at different scales.
Either that, or Dark Energy is an attractive force at "short" scale, to provide the local anomalies (non-expansion) from global expansion due to the cosmological constant.
> Those would indicate fluidic behaviour.
Behavior that is disallowed by observation.
...
> > Now what I'd like to propose is, if inertia derives > > from all the mass in the Universe (ala Mach), and > > the speed of *this* effect (establishment of > > inertia) is large-but-finite, what if Dark Matter is > > simply "echos" of an effect of the event horizons > > (say) that spent time in any given bit of space? > > Expansion also looks like everything shrinking in > > place (due to increasing clock rates). I mean if > > we are sky-balling...
> For that matter, we could even theorize that Dark > Matter and Dark Energy is just standard gravity's > symmetry breaking as the Universe cools > toward absolute zero, turning into two different > forces: a super-gravity and an anti-gravity.
Dark Matter was present at the time the CMBR quenched, and Dark Energy was too I believe. So it has nothing to do with "being cold", as distinct from "cooling". But since cooling is an effect of expansion... the cart is trying to pull itself.
dlzc wrote: > On Nov 6, 3:26 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote: >> Well, this article isn't talking about "Dark Fluid" but >> "Dark Fields". Different theories, though I don't know >> what the explanation of Dark Fields are supposed to be >> yet. The only explanation is that it is an extension of >> MOND to account for cluster deficiencies.
> It doesn't fix microlensing, so it is a patch to a flawed model.
>> But getting back to Dark Fluid, why do you say it >> violates what we see? Dark Fluid is supposed to be >> a complete alternative to MOND, Dark Matter >> and Dark Energy, so the fact that it "decays" into >> something similar to Dark Matter is exactly what it >> was supposed to do at some particular scale.
> Then it is Dark Matter, and no solution.
>> Dark Energy is a repulsive force, Dark Matter an >> attractive force, both acting on the same medium >> albeit at different scales.
> Either that, or Dark Energy is an attractive force at "short" scale, > to provide the local anomalies (non-expansion) from global expansion > due to the cosmological constant.
I think that's the entire point of Dark Fluid, it's the same energy acting as an attractive force at shorter scales, but as a repulsive force at greater distances.
Also it's been noted before that the acceleration constant in MOND is directly linked to the Dark Energy effect range. Though they don't know quite why that would be.
>> Those would indicate fluidic behaviour.
> Behavior that is disallowed by observation.
What observation is that?
> Dark Matter was present at the time the CMBR quenched, and Dark Energy > was too I believe. So it has nothing to do with "being cold", as > distinct from "cooling". But since cooling is an effect of > expansion... the cart is trying to pull itself.
On Nov 9, 5:08 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote:
> dlzc wrote: > > On Nov 6, 3:26 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote: > >> Well, this article isn't talking about "Dark Fluid" but > >> "Dark Fields". Different theories, though I don't know > >> what the explanation of Dark Fields are supposed to be > >> yet. The only explanation is that it is an extension of > >> MOND to account for cluster deficiencies.
> > It doesn't fix microlensing, so it is a patch to a flawed > > model.
> I thought that's why they created it?
MOND covers rotation curves. Dark Fields fixes cluster movements. Neither touches microlensing.
> >> But getting back to Dark Fluid, why do you say it > >> violates what we see? Dark Fluid is supposed to be > >> a complete alternative to MOND, Dark Matter > >> and Dark Energy, so the fact that it "decays" into > >> something similar to Dark Matter is exactly what it > >> was supposed to do at some particular scale.
> > Then it is Dark Matter, and no solution.
> >> Dark Energy is a repulsive force, Dark Matter an > >> attractive force, both acting on the same medium > >> albeit at different scales.
> > Either that, or Dark Energy is an attractive force at > > "short" scale, to provide the local anomalies > > (non-expansion) from global expansion due to the > > cosmological constant.
> I think that's the entire point of Dark Fluid, it's the > same energy acting as an attractive force at shorter > scales, but as a repulsive force at greater distances.
Such is not required in GR, however (which does microlensing). What is required is an anomalous amount of mass in medium scales, and an anomalous amount of attraction at slightly larger scales, and the expansion happens on its own. Because gravity is no sort of force.
> Also it's been noted before that the acceleration > constant in MOND is directly linked to the Dark > Energy effect range. Though they don't know > quite why that would be.
Yes, that makes no sense at all.
...
> >> Those would indicate fluidic behaviour.
> > Behavior that is disallowed by observation.
> What observation is that?
No viscosity, no pressure.
> > Dark Matter was present at the time the > > CMBR quenched, and Dark Energy was too I > > believe. So it has nothing to do with "being cold", > > as distinct from "cooling". But since cooling is > > an effect of expansion... the cart is trying to pull > > itself.
> Also it's been noted before that the acceleration constant in MOND is > directly linked to the Dark Energy effect range. Though they don't know > quite why that would be.
> The interaction between matter and S-T geometry, > as explained by General Relativity.
> No charge,
I should hope not. That is a reference to a model, a description of how gravityt behaves at scales larger than atoms but not too much larger than solar systems.
I suppose you'd charge for the answer to "what is gravity at the quantum level"?
> On Nov 9, 5:08 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote: >> dlzc wrote: >>> On Nov 6, 3:26 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote: >>>> Well, this article isn't talking about "Dark Fluid" but >>>> "Dark Fields". Different theories, though I don't know >>>> what the explanation of Dark Fields are supposed to be >>>> yet. The only explanation is that it is an extension of >>>> MOND to account for cluster deficiencies. >>> It doesn't fix microlensing, so it is a patch to a flawed >>> model. >> I thought that's why they created it?
> MOND covers rotation curves. Dark Fields fixes cluster movements. > Neither touches microlensing.
Okay.
>> I think that's the entire point of Dark Fluid, it's the >> same energy acting as an attractive force at shorter >> scales, but as a repulsive force at greater distances.
> Such is not required in GR, however (which does microlensing). What > is required is an anomalous amount of mass in medium scales, and an > anomalous amount of attraction at slightly larger scales, and the > expansion happens on its own. Because gravity is no sort of force.
Why would having more mass and more attraction at certain scales create a repulsion at even larger scales? What in GR suggests such a thing?
>> Also it's been noted before that the acceleration >> constant in MOND is directly linked to the Dark >> Energy effect range. Though they don't know >> quite why that would be.
> Yes, that makes no sense at all.
Maybe because there is an underlying common mechanism which we have not uncovered yet?
>>>> Those would indicate fluidic behaviour. >>> Behavior that is disallowed by observation. >> What observation is that?
> No viscosity, no pressure.
A superfluid has no viscosity either. And pressure is a relative thing.
>>> Dark Matter was present at the time the >>> CMBR quenched, and Dark Energy was too I >>> believe. So it has nothing to do with "being cold", >>> as distinct from "cooling". But since cooling is >>> an effect of expansion... the cart is trying to pull >>> itself. >> Maybe that's when gravity started breaking?
> ... whatever gravity is...
Perhaps gravity is the force of attraction between space-time particles?
On Nov 14, 11:57 am, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote:
> dlzc wrote: > > On Nov 9, 5:08 pm, Yousuf Khan <bbb...@spammenot.yahoo.com> wrote: > >>dlzc wrote: ... > >> I think that's the entire point of Dark Fluid, it's the > >> same energy acting as an attractive force at shorter > >> scales, but as a repulsive force at greater distances.
> > Such is not required in GR, however (which does > > microlensing).
Correction: GR + Dark Matter does microlensing.
> > What is required is an anomalous amount of mass in > > medium scales, and an anomalous amount of > > attraction at slightly larger scales, and the > > expansion happens on its own. Because gravity is > > no sort of force.
> Why would having more mass and more attraction at > certain scales create a repulsion at even larger scales?
GR alone produces expansion, *without* the cosmological constant. The cosmological constant was added to neutralize the effect inherent in the model to describe a static Universe, then subsequent observation modified that constant to some intermediate (???) value.
> What in GR suggests such a thing?
Gravity is not a force. Expansion and relaxation are a natural result of the second law of thermodynamics.
> >> Also it's been noted before that the acceleration > >> constant in MOND is directly linked to the Dark > >> Energy effect range. Though they don't know > >> quite why that would be.
> > Yes, that makes no sense at all.
> Maybe because there is an underlying common > mechanism which we have not uncovered yet?
We are surrounded by the *now*. The relationship is between the now and the then. The mechanism is here...
> >>>> Those would indicate fluidic behaviour.
> >>> Behavior that is disallowed by observation.
> >> What observation is that?
> > No viscosity, no pressure.
> A superfluid has no viscosity either. And pressure > is a relative thing.
If it quacks like a duck, and walks like a duck, Dark Fluid = Dark Matter
> >>> Dark Matter was present at the time the > >>> CMBR quenched, and Dark Energy was too I > >>> believe. So it has nothing to do with "being cold", > >>> as distinct from "cooling". But since cooling is > >>> an effect of expansion... the cart is trying to pull > >>> itself.
> >> Maybe that's when gravity started breaking?
> > ... whatever gravity is...
> Perhaps gravity is the force of attraction between > space-time particles?
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