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Problems With Dark Matter


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Dark matter bashing is getting very popular.

 

Milky ways' companions don't fit dark matter models(The Royal Astronomical Society)

 

Our model appears to rule out the presence of dark matter in the universe, threatening a central pillar of current cosmological theory. We see this as the beginning of a paradigm shift, one that will ultimately lead us to a new understanding of the universe we inhabit.

 

No dark matter within 13,000 lightyears

Edited by PetTastic
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Dark Matter is an IDEA that was made up to try and explain problems with a belief that the redshift of stellar bodies works the same as the sound of a train whistle passing by.

 

More problems with DM:

 

 

http://hubblesite.org/newscenter/archive/releases/2012/10/full/

 

 

http://www.sciencedaily.com/releases/2011/10/111017124344.htm

 

 

.

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Interesting read. What I did not get from this (though implied) that Dark Matter does not show itself our galaxy's halo ?

 

How could previous estimates be that far off, when it was thought the stuff we do see is between 4-5% of all there is.

 

It is starting to smell like the 19th Century Aether. A separate independently derived test would nail the coffin of it though.

 

Have to wait and see.

 

maddog

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The survey of 400 red giants would also seem to kill of MOND if no one can't find a problem with the analysis or data.

It only found normal matter and normal gravity.

 

The large structure around the Milkyway is even odder, at a million lightyears across, just the expansion of space would have a significant effect on it.

There are globular clusters as part of this flat disk of material, are they younder or old than the bigger structure.

The whole thing does not fit dark matter theory.

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Just yesterday a new result was published showing that study to be incorrect. They made an incorrect assumption about how stars move within our galaxy, see here for the details: http://arxiv.org/abs/1205.4033

 

J

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Hi Jay-qu,

 

Just yesterday a new result was published showing that study to be incorrect. They made an incorrect assumption about how stars move within our galaxy, see here for the details: http://arxiv.org/abs/1205.4033
We show that this result is incorrect and that it arises from the invalid assumption that the mean azimuthal velocity of the stellar tracers is independent of Galactocentric radius at all heights; the correct assumption---that is, the one supported by data---is that the circular speed is independent of radius in the mid-plane.

This seems to imply that dark matter is exclusively associated with non mid plane observations where the circular speed is dependent on the mid plane Galactocentric radius. When the non mid plane circular speeds are considered independent of the Galactocentric radius of the mid plane minimal anti matter is detected.

 

So, in a nutshell, anti matter is the difference between perceiving non mid plane circular speeds as being either independent of or dependent on the mid plane Galactocentric radius.

Edited by LaurieAG
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I don't think it is quite a simple as using the "correct assumption"

 

Stars can only move following the path of their "correct assumption" if DM exists, without DM or MOND it is physically impossible.

 

As far as I can see the original paper assumed no DM and was expecting to stars to oscillate vertically through the plane of the disk as they orbit.

This motion is improbable if a DM halo exists & would imply the galaxy is growing?

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Hi PetTastic,

 

As far as I can see the original paper assumed no DM and was expecting to stars to oscillate vertically through the plane of the disk as they orbit.?

The refutation paper made a few assumptions in the 2 paragraphs after equation 11.

 

In this equation, 110 km s−1 and 21 km s−1 kpc−1 are ¯ V and @ ¯ V /@R at |Z| = 2.5 kpc. We find that @ ¯ V /@R is 7 km s−1 kpc−1 at Z = 0, growing to 11 km s−1 kpc−1 at |Z| = 1 kpc and 40 km s−1 kpc−1 at |Z| = 3.5 kpc. If we use h = 3.5 kpc (Bovy et al. 2012c), the gradients are larger by about 20%. For comparison, MB12 estimate that a gradient @ ¯ V /@R = 17 km s−1 kpc−1 is needed to make their analysis consistent with the expected amount of dark matter. MB12 dismiss this possibility, apparently because they confuse constraints on @Vc/@R with constraints on @ ¯ V /@R, as there are, in fact, no direct observational constraints on @ ¯ V /@R.

If you plot @ ¯ V /@R vs |Z| you get a straight line relationship that has 17 at its central point so the rest of the paper just questions the assumptions and findings of the refutation (i.e. our findings show a straight line but our equations prove otherwise) not the original paper.

Edited by LaurieAG
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Just yesterday a new result was published showing that study to be incorrect. They made an incorrect assumption about how stars move within our galaxy, see here for the details: http://arxiv.org/abs/1205.4033

J

I think Jay-qu has it right on. I did not find the original paper till just know, though I did read the latter and concur with its findings.

The previous paper made some assumptions that do not work out correctly with the original coordinate system and mechanics.

The second paper did and closely agrees with there is dark matter at the conventional wisdom amount of ~20%.

 

What have not found (at least credible) denial of dark matter in our local stellar neighborhood. What is the prohibition of dark matter

being near the computer that I am typing this on. I mean if we can't see it because it is dark, how do we know ?

 

maddog

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Hi maddog,

 

What have not found (at least credible) denial of dark matter in our local stellar neighborhood. What is the prohibition of dark matter

being near the computer that I am typing this on. I mean if we can't see it because it is dark, how do we know ?

There are some dark pools that can be found locally.

 

http://en.wikipedia.org/wiki/Dark_liquidity

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The most recent estimates on arxiv.org's papers give 551Km/s for the escape speed at the solar distance for the center of the Galaxy. The circular speed of the Sun around the galaxy is instead about 251Km/s.

 

 

http://forum.nasaspaceflight.com/index.php?topic=21886.0

 

 

So who needs dark matter?

 

 

To me, by definition, it is not so much dark matter holding the stars in which should fly out of our galaxy but more a matter of it slowing down stars so they cannot reach a speed where they would fly out of our galaxy. How can a star travel too fast if gravity is constantly pulling it back?

 

Since our solar system would also be in the grip of dark matter, do we see any planets in inappropriate orbits for their speed?

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Our galaxy is said to be some ten billion years old. That means that in ten billion years, our sun has been around the galaxy some fifty times.

 

If you accept that Dark Matter holds everything in place in the galaxy, then surely over time all the stars will slow down as DM drags at them (like friction).

 

If this is so, then stars would have been moving much faster at one time, so our galaxy would have been a lot bigger than now and it would be shrinking.

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Hi maddog,

 

Is that where my Lucent stock went when it tanked back in 2001. :P

Those dark ones are a bit like Schrodingers cat, if they ever have to open the box just hope that the bloody thing is alive. I don't think it works when you put in a dead one and expect a live one out but you'd never know these days :huh::( .

 

Wouldn't it be good if all papers had to have a simple picture in their abstract.

 

In this paper, we show that the analysis used by MB12 is flawed. The main error is that they assume that the mean azimuthal (or rotational) velocity ¯ V of their tracer population is independent of Galactocentric cylindrical radius R at all heights (i.e., ¯ V (R, Z) = ¯ V (Z)). This assumption is not supported by the data, which instead imply only that the circular speed Vc is independent of radius in the mid-plane.

So if you use R at all heights you see a group of objects rotating around a common galactic center but if you get the circular speed and work back to use as r2 or r3 (in the image) you need dark matter to compensate.

post-2995-0-40511800-1339067896_thumb.jpg

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Guest MacPhee

In the history of Science, many non-existent things have been thought up, and honestly believed in for a while. Like "Phlogiston" and "Caloric Fluid".

 

Isn't "Dark Matter" probably another example?

Edited by MacPhee
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Dark Energy, Dark Matter and Supermassive Black Holes – Is There a Connection?

 

 

I am fascinated by black holes. When I read that Kretchmann’s Invariant meant that the central singularity of a black hole must be real, I thought this really means that BHs are unique. Because of this fact alone, I thought it verges on insanity to hold that BHs are ordinary and should be regarded like any other massive object in the universe.

 

Let us suppose that there are such things as BH singularities or as close to being singularities as may be needed to produce the effect of “virtually” infinite density, virtually infinitely tight spacetime radius of curvature and virtually infinitely strong gravitational fields. “Infinite” means as great as may ever be necessary to account for whatever effects need accounting. Quantities just “tend” toward infinity.

 

Infinite also means that if one attempts to graph an infinite quantity, one must truncate the plot and draw “asymptotes” that mean that the curve “approaches” infinity. Or perhaps it approaches a surrogate value very close to the value achieved at infinity, and would do so more and more closely if only there was a long enough piece of paper. An asymptotic curve never gets to where it is going.

 

I thought that if this is true, there must be something wrong with the way the gravitational field of BHs is commonly described. One must draw a gravitational field strength diagram of an ordinary object as a parabola, nearer the center, having a maximum (or a minimum, if a gravitational potential well is intended) passing through the center of the object (as if it was a point mass). With a gravitational singularity, one cannot draw the curve so that it passes through the center of the object. It has no maximum (or minimum). This is absolutely not a “parabolic” or inverse square gravitational field strength diagram. This is something entirely different.

 

I believe that the universe adheres to mathematical laws including the pure laws of geometry. Never mind about spacetime being curved and non-Euclidean. No interpretive theorem can upset strict geometry. This is a gravitational field diagram, so relativistic spacial curvature is already implied and taken into account. Besides geometry, I believe in the power of symmetry. If there is an asymptote nearest to the vertical axis, there must also be an asymptote nearest the horizontal axis.

 

Wait!

 

I know what this is. It is a hyperbola! Black holes must generate a hyperbolic gravitational field.

 

So, I looked at Newton’s law of gravity,

 

F = - GMm/r2,

 

and wondered what would happen if

 

F = - GMbhm/rr* where r* is the unit vector of r, for dimensional integrity.

 

I call this an “adjusted” Newton’s law for black holes. It is hyperbolic. Using this, I followed analogous steps as with “raw” Newton’s law and I obtained

 

v = (GMbh/r*)½

 

which is an amazing result.

 

This says that the stellar orbital velocity around a spiral galactic center should not depend on r and, in fact, depends only on G and the mass of the galactic SBH at distances beyond the bulge. For a given galaxy with its central SBH, v is constant at larger r, say, well beyond 95% of the galactic stellar mass. I call it vo. This is the anomalous stellar velocity distribution, which is not really a distribution at all since all stellar orbital velocities are constant beyond the spiral galactic bulge.

 

I also noticed that, for a series of galaxies having different SBHs with different masses,

 

vo2 = GMbh

 

This is the M-sigma relation wherein a simple monotonically increasing relation exists between central SBH mass and the orbital velocities of outer stars, where no correlation is supposed to exist when there is an inverse square gravitational force. (This is because inverse square gravity falls off so rapidly.) This explanation of the M-sigma effect might be complicated by the fact that galaxies contain many tens of thousands of large stellar black holes too. These would add significantly to an “effective” Mbh in ways that would be hard to measure or predict.

 

But critics of the HSBH G-field postulate say that according to GR, gravitational force falls off as 1/r(n-1) where n = the number of spacial dimensions. So, a hyperbolic gravitational field can exist only in a 2-D region of spacetime.

 

I said “No problem.” All real black holes spin very fast, are non-spherical, greatly perturbed and cannot be expected to obey Birkhoff’s theorem. This says that perfectly spherical, stationary, unperturbed, black hole gravitational fields must be “asymptotically flat”. This means that, among other things, the field diagram must have no asymptotes, which then means that it must follow an inverse square relation. But, central supermassive black holes must spin even faster than most stellar black holes because so many stars have constantly in-fallen concertedly toward the BH singularity, increasing its angular momentum. Eventually, this produces “infinite” spin rate at the singularity (not at the event horizon, however).

 

Yes, the Kerr metric sort of stops or pauses (or at least the interpretations do) at the event horizon where a theoretically measurable finite non-zero angular momentum must transiently exist for this material. If it falls into the singularity, once there it should form a mere “ring” singularity. But, I deduce a possible new twist to the Kerr solution.

 

After all, what about all the comments that have been made to the effect that we do not really know what happens when spacetime curvature becomes so tight? Everybody says of black hole singularities: “As r → 0, GR → ???

 

Might Kerr or his interpreters have got it slightly skewed? Perhaps SBH EMS (energy/matter/spacetime) collapses not to a ring singularity, but to a virtually infinite spin rate SBH (below the event horizon) with a very very wide 2-D disk singularity. This disk singularity is unique enough to be associated with the amazing properties of a real black hole. It befits the legend that we make of it.

 

It becomes a very special 2-D EMS singularity that is a very broad, exceedingly thin flat disk. It is like a big whirling German pancake that spills beyond the griddle onto the floor and out the door. It is a strictly 2-D spacetime singular entity that can support a hyperbolic gravitational field. Maybe this is really what the Kerr metric actually implies, but rigid consensus mongers and obsessive seekers after conventional wisdom consistently misinterpret his analysis of GR.

 

How broad is “broad”?

 

I began to think large. Perhaps the mass or matter in the spacetime disk singularity stays under the event horizon (which must also be greatly distorted), but the gravitational spacetime coordinate component, which is immune to the event horizon, spreads out to include the periphery of the galaxy and beyond, even to the environs of other galaxies in a cluster or supercluster. It casts its hyperbolic 1/r gravitational field influence outward to infinity or to whatever passes for infinity in our universe. Maybe this is what it would really mean to be a 2-D infinite spin-rate disk singularity.

 

The hyperbolic 1/r black hole gravitational field has a potential energy profile that is generally higher than the equivalent inverse square gravitational field. The difference might constitute Dark Matter because M = E/c2. The 2-D 1/r gravitational spin-disk influence would display thickness in the galactic stellar assembly because the stars are the observers that would measure the spin-disk’s location. They are limited by the Heisenberg uncertainty principle, so they see the 2-D flat plane as a volume having thickness.

 

This flat plane is not totally flat, however. Being hyperbolic in nature, it would have an overall shape like an hyperboloid of one sheet. Looking like an hourglass or a saddle shape, It would not really be flat well beyond the galactic periphery. Its surface could therefore align more easily with other hyperbolic field surfaces generated by other SBHs in other galaxies. This alignment tendency may account for the large scale structure effect observed in sky surveys.

 

I reasoned that the enhanced 1/r gravitational field effect accounts for not only the M-sigma relation and the anomalous velocity dispersion, but the weak gravitational lensing, the Sunyaev-Zel’Dovich, the Sachs-Wolfe and yes, even the large scale structure effects. These are precisely the phenomena that are cited in support of Exotic Dark Matter. But DM need not be exotic. It may result simply from how we compute the masses of cosmological objects containing large black holes. Maybe this can teach us something we did not know about black holes and cosmologists can quite pretending that they already know everything.

 

Cosmologists at Cambridge, Cal Tech and the Perimeter Institute will not like this idea. Dozens of graduate students depend on Dark Matter research funding. I wouldn't dream of upsetting anybody's special interests. But, Nobel laureat Lev Landau said “Cosmologists are always wrong, but never in doubt.”

 

But, maybe Dark Matter could still be real. A little extra midnight oil let me see that if extended to include the whole universe from the time of the BB, the hyperbolic field becomes Dark Energy, as well as Dark Matter, by virtue of its generally higher gravitational potential energy compared to the equivalent inverse square field that must pervade the universe. This is only because M = E/c2. The extra gravitational potential energy has mass and when it transitions to a 3-D + time inverse square field, its potential energy becomes real energy in the form of the accelerating expansion of space and the apparent kinematic "repulsion" of cosmological objects.

 

As a matter of fact, Alan Guth says that the universe was once a quantum object. So, I say that it probably still is. Thus, the 2-D hyperbolic field may have been the highly excited “inflaton field” which decayed into the 3-D + time universe that we see today. This quantum transition would have been time dependent. It may still be going on. The higher potential energy of the hyperbolic field may currently be being realized as acceleration of expansion and the apparent “repulsion” between objects on a cosmic scale. The quantum superposition of yesterday fades into the relativistic reality of today.

 

I did not yell “Eureka!” But, Dark Matter and Dark Energy may be essentially the same. It all hangs together quite nicely.

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