Dark Matter is not matter?

[juanrga]

Saw this in the science news today.

 

The article is entitled "Serious Blow to Dark Matter Theories?

 

http://www.eso.org/p...c/news/eso1217/

 

The purpose of the study was to find dark matter around the sun and its surrounding mass relating to gravitational influences within our solar system. According to their observations and conclusions, none was found.

 

You cannot find something that does not exist url deleted

Edited April 20, 2012 by swansont

[Royston]

You cannot find something that does not exist <vixra link deleted>

 

You seem to be stating this as fact, and then post your own work from 'free for all' vixra.

 

DM seems to do a much better job, when it comes to large scale structure, not just galaxy rotation.

 

One example, MOND and the GR alternative TeVeS predicts gravitational lensing deflection should coincide with visible baryons in clusters. This has been tested, using the Bullet cluster, which shows there is a large discrepancy between the masses found from X-ray sources and gravitational lensing. A DM component remedies this.

 

EDIT: deleted link due to mod note

Edited April 20, 2012 by Royston

[swansont]

You cannot find something that does not exist url deleted

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Moderator Note

Again, this is not the place for discussion of alternative hypotheses. Such discussion belongs in its own thread in Speculations.

[Dekan]

Suppose Dark Matter actually exists, then won't there be some here on Earth?

 

After all, the Earth is part of the Universe. So if Dark Matter exists in the Universe, it should exist on Earth too. Then we could get at it, and examine its properties, at close quarters.

 

But this doesn't seem to be the case. Dark Matter apparently only exists at huge interstellar distances, thousands of light-years away from the Earth. Too far away for us to get our hands on the stuff.

 

This is convenient for theorists. They can say "Well, Dark Matter exists, but it's all so far away, that we can't show you any actual samples of it. But believe us, it's out there, a long way away."

 

Does that sound very convincing?

[imatfaal]

Dekan - the other problem is that we only really know how to contain, measure, and interact in the lab with stuff via the electromagnetic force. Dark matter does not interact via E-M - it might be as slippery to get hold of as neutrinos (or worse).

[juanrga]

You seem to be stating this as fact, and then post your own work from 'free for all' vixra.

 

The preprint (indexed by Scholar, submitted for publication...) gives a list of standard references, which summarize the null results of the hundred of direct and indirect search of dark matter. Since the preprint url has been deleted I will copy and paste some references from it.

 

Particle dark matter: evidence, candidates and constraints 2005: Phys. Rep. 405(5–6), 279–390. Bertone, G; Hooper, D; Silk, J.

 

First Results from the XENON10 Dark Matter Experiment at the Gran Sasso National Laboratory 2008: Phys. Rev. Lett. 100, 021303-1–5. Angle, J.; et al. (XENON Collaboration).

 

Constraining Dark Matter Models from a Combined Analysis of Milky Way Satellites with the Fermi Large Area Telescope 2011: Phys. Rev. Lett. 107, 241302-1–6. Ackermann, M.; et al. (The Fermi-LAT Collaboration).

etcetera.

 

This resembles all the null results when searching the aether. No?

 

People who cannot access to specialised literature cited still can find the related news. For instance check Fermi Space Telescope Fails to See Evidence Of Dark Matter

 

DM seems to do a much better job, when it comes to large scale structure, not just galaxy rotation.

 

It is a common myth to pretend that MOND only does galaxy rotation. The preprint remarks the different predictions done by MOND, all of which have been confirmed. This includes the use of MOND to study light deflection in galaxies and clusters. Again the references cited in the preprint give details. Again I am forced to copy and paste some of them:

 

Modified Newtonian Dynamics as an Alternative to Dark Matter 2002: Ann. Rev. Astron. Astrophys. 40, 263–317. Sanders, Robert H.; McGaugh, Stacy S.

 

The gravitational deflection of light in MOND 1994: arXiv:astro-ph/9406051v1. Bo, Q.; Wu, X.P.;Zou, Z. L.

One example, MOND and the GR alternative TeVeS predicts gravitational lensing deflection should coincide with visible baryons in clusters. This has been tested, using the Bullet cluster, which shows there is a large discrepancy between the masses found from X-ray sources and gravitational lensing. A DM component remedies this.

 

EDIT: deleted link due to mod note

 

As has been explained up to exhaust, in multiple places, the Bullet cluster results do not falsify MOND. Moreover, it has been shown that dark matter cannot explain the Bullet cluster Bullet Cluster: A Challenge to ΛCDM Cosmology and has been shown that some aspects of the Bullet cluster are explained by MOND but not by dark matter:

 

But some myths never die

Edited April 20, 2012 by juanrga

[pantheory]

You cannot find something that does not exist ...

We have lots of evidence that there is something or some influence there concerning the idea of dark matter. But it is only an assumption that it is matter since matter is the only thing that we know of that can increase the effects of gravity. Concerning galaxy clusters, for instance, reformulations of gravity like MOND (in its known forms) also require variable inputs that can be likened to dark matter inputs to Newtonian gravity in the standard formulations. In rare cases, nearly identical appearing galaxies seem to have different rotation curves of their stars. Why should there be different amounts of DM with possibly different DM distributions in "identical" appearing galaxies? but for the same reasoning why should there be different variables used/ inserted concerning alternative equations like MOND? These are some of the questions that are believed to have no obvious answers.

//

Suppose Dark Matter actually exists, then won't there be some here on Earth?

 

After all, the Earth is part of the Universe. So if Dark Matter exists in the Universe, it should exist on Earth too. Then we could get at it, and examine its properties, at close quarters.

 

But this doesn't seem to be the case. Dark Matter apparently only exists at huge interstellar distances, thousands of light-years away from the Earth. Too far away for us to get our hands on the stuff.

 

This is convenient for theorists. They can say "Well, Dark Matter exists, but it's all so far away, that we can't show you any actual samples of it. But believe us, it's out there, a long way away....."

A similar problem seems to exist with expanding space and the expansion of the universe. Expanding space (and therefore the expansion of the universe) is believed to be observable via redshifts of distant galaxies, but it cannot be seen in our neighborhood because it is believed that gravity compensates for it in our neighborhood and in the venue of groups and clusters. The same problem seems to exist for dark energy.

 

I expect these findings of my last link will not be the last word concerning similar studies/ observations concerning possible DM influences in our solar neighborhood, other than those presently being conducted concerning possible evidence here on Earth

 

As a result of such observations/ studies/ interpretations/ conclusions, many still consider dark matter and dark energy as "place holders" until more evidence concerning their nature, or better explanations, theory, etc., might come along.

//

Edited April 20, 2012 by pantheory

[juanrga]

We have lots of evidence that there is something or some influence there concerning the idea of dark matter.

 

The same kind of 'evidence' that did that 19th century astronomers postulated the existence of unseen mass, a new planet which was named Vulcan.

 

The first discovery of Vulcan was announced on 2 January 1860 during a meeting of the Académie des Sciences in Paris. Several re-discoveries and confirmations were done in posterior decades, somehow as discoveries of the hypothetical Dark Matter are announced in our days. This quote from a book of history must be relevant: «For the people of the late 19th century, Vulcan was real. It was a planet. It had theoretical credibility and had actually been seen. Even textbooks accorded it a chapter».

 

In despite of the claimed 'evidence' and of the announced 'discoveries' and 're-discoveries' Vulcan does not exist.

Edited April 20, 2012 by juanrga

[pantheory]

juanrga,

 

Link removed is a link to a dark matter thread that I just opened based upon a seemingly well written article concerning the problems with dark matter and related theory today, where alternative ideas like MOND and others might be further discussed.

 

 

General Info:

 

The OP link is not presently working so here's another similar one.

 

http://news-about-sp...luster14637861/

Edited April 21, 2012 by hypervalent_iodine
Thread advertisement removed.

[hypervalent_iodine]

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Moderator Note

pantheory, this is not the place to advertise your thread. Link removed.

[pantheory]

More observations and studies leading to more doubts concerning dark matter and the standard cosmological model.

 

http://www.ras.org.uk/news-and-press/219-news-2012/2118-do-the-milky-ways-companions-spell-trouble-for-dark-matter

[Open Accesss Library]

The equations could be wrong (that is always a possibility in an system) but, if I have the time line correct, it was noticed that angular velocities of galaxies and clusters did not match the amount of luminous material that we could observe, it was posited that a form of matter was around/about galaxies that was not interacting through emr but was gravitationally (and perhaps weakly).

 

Subsequent to this it was realised that this matter should not only help our equations of motion work out, we should be able to detect it because of its gravitational lensing effect; this was born out in observation.

[pantheory]

The equations could be wrong (that is always a possibility in an system) but, if I have the time line correct, it was noticed that angular velocities of galaxies and clusters did not match the amount of luminous material that we could observe, it was posited that a form of matter was around/about galaxies that was not interacting through emr but was gravitationally (and perhaps weakly).

There is another requirement that is needed to increase the galactic angular velocity of stars (their orbital momentum). The proposed dark matter orbiting the galaxy would need to have greater momentum than the stars within the galaxy with no explanation concerning how this hypothetical matter got its supposed momentum.

 

Subsequent to this it was realised that this matter should not only help our equations of motion work out, we should be able to detect it because of its gravitational lensing effect; this was born out in observation.

If there is no dark matter and instead the orbital-mechanics equation are wrong then one might expect that the lensing equations that predict more matter than we can see could also be wrong since both are based upon GR, and/or that we also have been misinterpreting what we have been observing.

//

Edited April 28, 2012 by pantheory

[juanrga]

Subsequent to this it was realised that this matter should not only help our equations of motion work out, we should be able to detect it because of its gravitational lensing effect; this was born out in observation.

 

It was initially believed that the difference between the observed gravitational lensing and the gravitational lensing predicted by GR could be due to a hypothetical missing mass, which was named dark matter. However, this hypothetical mass has never been found where it was supposed to exist once.

 

Today, observed gravitational lensing can be explained by theories such as MOND, TeVeS, and others without any appeal to a hypothetical dark matter.

Edited April 28, 2012 by juanrga

[IM Egdall]

Good article explaining the latest evidence putting dark matter into question:

 

http://www.newscientist.com/article/dn21732-nearby-darkmatterfree-zone-poses-cosmic-conundrum.html

[hypervalent_iodine]

!

Moderator Note

Open Access Library,

Though I suspect I am talking to a spam bot, I'm giving you the benefit of the doubt here and giving you a warning.

Copying and pasting another member's post and using it as your own is not tolerated. Please do not do it again. If you do, it will be taken it as confirmation that you are indeed a spam bot and you're account will be banned.

[IM Egdall]

How about the idea that the (observable) universe contains roughly 5% ordinary matter, 25% dark matter, and 70% dark energy. This sum gives the so-called critical mass/energy density needed for a flat universe (zero overall spacetime curvature). And observations show the observable universe is indeed flat. Analysis of the Cosmic Microwave Background is one example.

 

So if there is no dark matter (which I doubt), then the total matter/energy in the observable universe would be too little for the flat universe we see, wouldn't it?. It would imply an open universe of negative overall spacetime curvature. Does anyone know if MOND or any other theory has an answer for this? Or am I missing something here?

[juanrga]

How about the idea that the (observable) universe contains roughly 5% ordinary matter, 25% dark matter, and 70% dark energy. This sum gives the so-called critical mass/energy density needed for a flat universe (zero overall spacetime curvature). And observations show the observable universe is indeed flat. Analysis of the Cosmic Microwave Background is one example.

 

So if there is no dark matter (which I doubt), then the total matter/energy in the observable universe would be too little for the flat universe we see, wouldn't it?. It would imply an open universe of negative overall spacetime curvature. Does anyone know if MOND or any other theory has an answer for this? Or am I missing something here?

 

That percent of dark matter is obtained from the difference between the observation and the prediction done using GR. If instead GR you use some other theory, then you do not need dark matter to explain the observations.

 

Regarding CMB, precisely MOND was the only theory that predicted the correct first and second peaks (ligth blue), whereas the dark matter model (orange) failed

 

 

After the CMB data become available, dark matter theorists changed the dark matter model to fit the data a posteriori. The problem is that they are using now some parameter values in disagreement with other tests.

[IM Egdall]

That percent of dark matter is obtained from the difference between the observation and the prediction done using GR. If instead GR you use some other theory, then you do not need dark matter to explain the observations.

 

Ya, I knew that -- its obvious. But do you know exactly what theory other than dark matter predicts the critical density needed for a flat universe without the use of dark matter? I need specifics, please.

Edited May 2, 2012 by IM Egdall

[pantheory]

Ya, I knew that -- its obvious. But do you know exactly what theory other than dark matter predicts the critical density needed for a flat universe without the use of dark matter? I need specifics, please.

There are a great many non-mainstream theories that propose and support a flat universe. One of the only theories that does not necessarily predict a flat universe is the BB model, concerning most of its variations. Any theory that uses GR will predict numerous possibilities other than a flat universe. Most theories that either have MOND or another gravity model without dark matter generally must predict a flat universe if space cannot curve or warp. Most, but not all of the alternative flat-universe models are infinite-universe models. Examples are steady-state models of Hoyle and many others. Plasma Cosmology is an infinite model. Some tired light models are infinite, etc. Paul Dirac's expanding matter and space model proposes a flat universe. Most diminution of matter models propose a flat universe, etc.

 

So the idea of a non-flat universe is unique to the BB model or other models that support GR, in my opinion. What sayeth you my friend?

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Edited May 3, 2012 by pantheory

[sammy7]

that entire model (einsteins general relativity) or whatever sucks as evidenced by the number of "fillers" if you will that has to be put into it to "prop" it up (dark energy dark matter blah blah blah) never ever been observed....the scientific oligarchy owns us all arrrgghhhh! lol... just bored...

Edited May 17, 2012 by sammy7

[pantheory]

that entire model (einsteins general relativity) or whatever sucks as evidenced by the number of "fillers" if you will that has to be put into it to "prop" it up (dark energy dark matter blah blah blah) never ever been observed....the scientific oligarchy owns us all arrrgghhhh! lol... just bored...

Dark matter is needed to support General Relativity, which is the mathematical foundation of the Big Bang model. It is conceivable that another mathematical model of gravity could replace GR in the Big Bang model.

 

Dark Energy, on the other hand, is not needed by the BB model, but its inclusion into the model was thought to be the only explanation consistent with observations of type 1a supernova. Any other cosmological model would also need to explain this same data by a different explanation, or otherwise it would also need to incorporate the dark energy idea.

 

...the scientific oligarchy owns us all arrrgghhhh! lol... just bored..

The Big Bang is presently the only considered model in cosmology. When seriously contradicted by observations, the BB model must be able to evolve. When or if it no longer could, it would be replaced.

//

Edited May 17, 2012 by pantheory

[sammy7]

The Big Bang is presently the only considered model in cosmology. When seriously contradicted by observations, the BB model must be able to evolve. When or if it no longer could, it would be replaced.

 

hay im not a astronomer or cosmologist (as you may be?) but i found this guys videos the other day on youtube and found them quite intriguing

 

[pantheory]

The Big Bang is presently the only considered model in cosmology. When seriously contradicted by observations, the BB model must be able to evolve. When or if it no longer could, it would be replaced.

 

hay im not a astronomer or cosmologist (as you may be?) but i found this guys videos the other day on you tube and found them quite intriguing

This has some interest to me for discussion but is unrelated to dark matter. To discuss this material elsewhere PM me and we might do so in another venue. The rules prohibit such discussions here unless they are news related

Edited May 21, 2012 by pantheory

[Spyman]

On the local dark matter density

 

Authors: Jo Bovy, Scott Tremaine (IAS)

(Submitted on 17 May 2012)

 

Abstract: An analysis of the kinematics of 412 stars at 1-4 kpc from the Galactic mid-plane by Moni Bidin et al. (2012) has claimed to derive a local density of dark matter that is an order of magnitude below standard expectations. 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. We demonstrate that the assumption of constant mean azimuthal velocity is physically implausible by showing that it requires the circular velocity to drop more steeply than allowed by any plausible mass model, with or without dark matter, at large heights above the mid-plane. Using the correct approximation that the circular velocity curve is flat in the mid-plane, we find that the data imply a local dark-matter density of 0.008 +/- 0.002 Msun/pc^3= 0.3 +/- 0.1 Gev/cm^3, fully consistent with standard estimates of this quantity. This is the most robust direct measurement of the local dark-matter density to date.

Link: http://arxiv.org/abs/1205.4033v1