Could Dark Matter Possibly Be . . .

[harry]

G'day from the land of ozzzzzzzz

Science reseacrh in the next 1 to 7 years will resolve many issues including dark matter and dark energy.

Research with the LSST will make it easier.

http://arxiv.org/abs/0805.2366
LSST: from Science Drivers to Reference Design and Anticipated Data Products

Authors: Z. Ivezic, J.A. Tyson, R. Allsman, J. Andrew, R. Angel, et al, for the LSST Collaboration
(Submitted on 15 May 2008)

Abstract: We describe the most ambitious survey currently planned in the visible band, the Large Synoptic Survey Telescope (LSST). The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the Solar System, exploring the transient optical sky, and mapping the Milky Way. LSST will be a large, wide-field ground-based system designed to obtain multiple images covering the sky that is visible from Cerro Pachon in Northern Chile. The current baseline design, with an 8.4m (6.5m effective) primary mirror, a 9.6 sq. deg. field of view, and a 3.2 Gigapixel camera, will allow about 10,000 sq.deg. of sky to be covered using pairs of 15-second exposures in two photometric bands every three nights on average, with typical 5-sigma depth for point sources of r=24.5. The system is designed to yield high image quality as well as superb astrometric and photometric accuracy. The survey area will include 30,000 sq.deg with delta<+34.5, and will be imaged multiple times in six bands, ugrizy, covering the wavelength range 320-1050 nm. The project is scheduled to have first light in 2014 and the beginning of survey operations in 2015. About 90% of the observing time will be devoted to a deep-wide-fast survey mode which will observe a 20,000 sq.deg. region about 1000 times (summed over all six bands) during the anticipated 10 years of operations, and yield a coadded map to r=27.5. These data will result in databases including 10 billion galaxies and a similar number of stars, and will serve the majority of science programs. (abridged)

[GOD]

We know what gravity can do, but! we do not know what gravity is.

What gravity is may be a meaningless question. It is defined by what it does, and that we understand very well. Indeed, under GR, what gravity actually is happens to be well understood as a distortion of spacetime. So it's very likely we do know "what" gravity is.

Chris> No, human beings do not yet know what gravity is. It isn't a distortion of spacetime. It is a particle flow. The reason humanity doesn't know this yet is because gravitons are smaller than they can currently detect. Current theories about this particle are far from correct.

Gravity is not a simple, singular force. It has many aspects and varies depending on the composition of the objects in question and their distance from each other. Gravity differs between objects of different compositions. Like compositions attract each other more because of the compatibility of their makeup.

Magnetism enters into the equation with metals. Where there is flexibility for objects to turn, one or both maneuver such that they are magnetically aligned. This consumes a slight amount of time, and thus an iron ball falls more slowly in a vacuum than an object of comparable weight that has a slight magnetic retention.

Organic compounds react to gravity in a different manner than in-organic compounds. This is due to the complex bonding between atoms. Organic material in general will not experience the interference that matter with free electrons does during a gravity attraction. Inorganic material takes time out to shed or take on electrons, slowing its movement.

However currently for the most part, human beings find their understanding of gravity to be incomplete because they are not taking into consideration the repulsion force that large bodies, such as stars and planets, generate toward each other. This is humanity's next step in better understanding gravity.

[harry]

G'day God

You said

However currently for the most part, human beings find their understanding of gravity to be incomplete because they are not taking into consideration the repulsion force that large bodies, such as stars and planets, generate toward each other. This is humanity's next step in better understanding gravity.

What repulsion force?

[Chris Peterson]

What repulsion force?

That would be the force of laughter, as the entire Universe reacts to the previously given explanation for gravity.

[harry]

G'day Chris

The only repulsive force that I know is in relation to atomic structure.

Unless we have anti matter. Must look it up.

[Chris Peterson]

The only repulsive force that I know is in relation to atomic structure.

The electromagnetic force is both attractive and repulsive. While it is the only force that is significant in determining atomic and molecular structure, its effects (both attractive and repulsive) are apparent at scales far greater than atomic.

Dark energy may be a manifestation of repulsive gravity, or it may be something else altogether. Certainly, however, there is strong evidence of a repulsive "force" driving the expansion of the Universe (I use "force" loosely here, as it may not be a force in the usual sense).

Unless we have anti matter. Must look it up.

Antimatter behaves the same as normal matter in terms of the four fundamental forces.

[makc]

What repulsion force?

That would be the force of laughter, as the entire Universe reacts to the previously given explanation for gravity.

How dare you to laugh to the word of God?

[harry]

G'day from the land of ozzzzzzzz

This forum is so slow that I may have to talk with God one on one.

[GOD]

What repulsion force?

harry> Why would the planets not drift into the Sun? Are the orbits all that swift so that centrifugal force is extreme? Humans have calculated the force of gravity that at first they assumed was equal for all objects but since have come to understand is stronger for larger objects. They have formulas for the force of gravity which have proved accurate on the surface of planet Earth. These formulas are incomplete, and would not work as expected elsewhere, however.

The repulsion force is infinitesimally smaller than the force of gravity, but has a sharper curve so that it equals the force of gravity at the point of contact. It only manifests in nature when two objects of similar mass are free to move and dominate the immediate environment. All objects on the surface of the Earth are dominated by the Earth's intense force of gravity as well as other factors such as surface tension, friction, or chemical bonding, so that the repulsion force cannot be recognized.

The repulsive force phenomena shall be discovered when measurements of objects of equal mass are conducted in a space lab, far away from any planetary body so that free movement is possible, in an environment where other factors are eliminated or negated. Two balls shall be placed in a cage. One put in motion toward the other. The exchange is examined microscopically. One will be almost at the point of contact for repulsion to come into play: They do not touch. They do not bounce off one another. They do not touch!

[Martin]

Qev wrote:

Just thought I'd point out, leptons, photons, W and Z bosons, and neutrinos are all non-baryonic matter.

I do not think this is correct nor do I think it would be a good example.

I do think that when I first suggested that we may have gravity wrong once again -goes unchallenged (with a partial exception to Chris). We could likely find that we will have to "add to" or "expand upon" our theories.

Of course, I could be wrong but there are some prominent scientists that do not agree entirely with the standard model or dark matter and energy either. I think the only thing dark going on here are the holes in our theories.

[Chris Peterson]

Qev wrote:

Just thought I'd point out, leptons, photons, W and Z bosons, and neutrinos are all non-baryonic matter.

I do not think this is correct nor do I think it would be a good example.

Well, it is correct by definition. Why do you think the example is poor? Neutrinos have been considered a candidate for dark matter, although that theory is currently not too well regarded.

[harry]

G'day from the land of ozzzzzzz

Lately there have been a number of papers that have excluded dark matter.

Eg

http://arxiv.org/abs/0806.1513
Galaxy rotation curves without non-baryonic dark matter and modifications to gravity: effect of the Ampere force

Authors: David Tsiklauri (University of Salford)
(Submitted on 9 Jun 2008)

Abstract: Using an example of the galaxy, an attempt is made to explain the flat rotational curves of galaxies by means of the Ampere force. This is the first attempt of fitting the rotational curve without both non-baryonic dark matter and modifications to gravity. Using acceptable models for the galactic magnetic field and plausible physical parameters, we find that the flat rotational curves can be obtained based purely on the observed baryonic (visible) matter distribution and the ampere force term in the static MHD equation of motion. We also study effects of strength of the magnetic field, its pitch angle and length scale on the rotational curves.

http://arxiv.org/abs/0806.1131
Newtonian mechanics & gravity fully model disk galaxy rotation curves without dark matter

Authors: Dilip G. Banhatti (School of Physics, Madurai-Kamaraj University, Madurai, India)
(Submitted on 6 Jun 2008 (v1), last revised 10 Jul 2008 (this version, v4))

Abstract: EGRET gamma-ray archival data used with GALPROP software show two ringlike structures in Milky Way Plane which roughly tally with distribution of stars ([1] & references therein). To understand fully the implications of this and similar results on detailed structure and rotation curve of especially Milky Way Disk as well as rotation curves of other galaxies as derived from spatially resolved spectroscopic data-cubes, a re-examination of the basis of the connection between mass density and rotation curve is warranted. Kenneth F. Nicholson's approach [2], which uses only Newtonian dynamics & gravity, is presented.

[harry]

G'day

In respect for God,

I'm going to look at the repulsive gravity.

http://arxiv.org/abs/0809.5040
Dark Energy: A Missing Physical Ingredient

Authors: M. I. Wanas
(Submitted on 29 Sep 2008)

Abstract: Recent observation of supernovae type Ia show clearly that there is a large scale repulsive force in the Universe. Neither of the four known fundamental interactions can account for this repulsive force. Gravity is known to be the interaction responsible for the large scale structure and evolution of the Universe. The problem with gravity is that it gives rise to a force which is attractive only. Gravity theories, including General Relativity, deals with gravity as an attractive force. Although this is consistent with our experience in the solar system and other similar astrophysical systems, gravity theories fail to account for SN type Ia observation. So, we are in a real problem concerning the interpretation of these observation. This problem is only ten years old. In order to go out of this problematic situation, scientists have suggested the existence of a type of energy in the Universe that is responsible for the above mentioned repulsive force. They have given this type of energy the exotic term {\it "Dark Energy"}. Although this type of energy forms more than two thirds of the energetic contents of our Universe, its reasonable nature is missing in all gravity theories.

This has opened a can or worms.

Looks like I'll be reading many links to understand the process.

[Martin]

Chris wrote:

Neutrinos have been considered a candidate for dark matter, although that theory is currently not too well regarded.

Why is this not well regarded any longer?

[harry]

G'day from the land of ozzzzzzzzz

This paper may be of interest

Dark Matter Concentration in the Galactic Center
http://adsabs.harvard.edu/abs/1998ApJ...500..591T
Tsiklauri, David; Viollier, Raoul D.
Astrophysical Journal v.500, p.591 (ApJ Homepage)
Jun-98

Abstract
It is shown that the matter concentration observed through stellar motion at the Galactic center is consistent with a supermassive object of 2.5 x 106 solar masses composed of self-gravitating, degenerate, heavy neutrinos. This result is opposed to the alternative black hole interpretation. According to the observational data, the lower bounds on possible neutrino masses are m nu >= 12.0 keV/c2 for g = 2 or m nu >= 14.3 keV/c2 for g = 1, where g is the spin degeneracy factor. The advantage of this scenario is that it could naturally explain the low X-ray and gamma-ray activity of Sgr A*, i.e., the so-called blackness problem of the Galactic center.

and

Black holes or dark clusters in M31 and M32?
http://adsabs.harvard.edu/abs/1989ApJ...337...84G

Abstract
Recent spectroscopic data and dynamical modeling indicate the presence of dark matter within the nuclei of M31 and M32. If these nuclei do not contain massive black holes, the most likely alternative form for the dark matter is a cluster of low-mass stars or degenerate remnants. Here it is shown that simple physical considerations place lower limits of about 0.1 arcsec on the half-mass radii of such clusters if they have survived in their present form over much of the age of the universe. Therefore, Space Telescope observations should rule out such clusters, or resolve them.

[Chris Peterson]

Chris wrote:

Neutrinos have been considered a candidate for dark matter, although that theory is currently not too well regarded.

Why is this not well regarded any longer?

Neutrinos travel at relativistic velocities, and one consequence of this is a particular fine scale structure that we do not see in recent, high resolution microwave maps of the Universe. So while neutrinos may be a component of dark matter, they are not sufficient by themselves. To match observations, you need slow moving, weakly interacting particles. This is why cold dark matter is favored at the most likely dark matter candidate, and neutrinos are no longer considered too seriously.

[harry]

G'day Chris you maybe interested in this paper

http://adsabs.harvard.edu/abs/1994PrPNP..32...51V
Neutrino halos around baryonic stars and supermassive neutrino stars - Atoms of the macrocosm?
Viollier, R. D.
Institute of Theoretical Physics and Astrophysics, University of Cape Town, Rondebosch 7700, Republic of South Africa
Progress in Particle and Nuclear Physics, Volume 32, p. 51-74.
00/1994

Abstract
The properties and observational implications of self-gravitating degenerate heavy neutrino matter clustered around baryonic stars are investigated for neutrino masses in the range of 10 to 25 keV/c2. As a test of our ideas, we propose a new experiment aimed at observing the radiative decay of such neutrinos, which the sun might have accumulated in a halo of a few solar masses and a few light years radius. We further study the characteristics of supermassive `stars' consisting of self-gravitating degenerate neutrino matter. Such compact dark objects could be as massive as 109.5 to 106.5 solar masses, with radii of about one to ten light days; they might thus mimic phenomena that are expected around the supermassive black holes recently purported at the centres of some galaxies, including our own, and quasi-stellar objects. Finally, we turn to the cosmological consequences of such a standard neutrino. Overclosure of the universe could be avoided through (i) plasma reheating due to gravitational collapse of primordial neutrino density fluctuations prior to recombination, and (ii) annihilation of the heavy neutrinos into light neutrinos in supermassive degenerate `neutrino stars' after recombination. These compact dark objects could play an important role in the formation of galactic nuclei.

[Chris Peterson]

G'day Chris you maybe interested in this paper...

Not particularly. It is 14 years old (a long time in this field), and if you check the citation history it's rarely referenced, and only by a few researchers (including the author himself in other papers).

But thanks for the reference, which does help demonstrate what I said: neutrinos are not generally considered a good candidate for dark matter, hence the relative lack of publications on the subject, especially recent publications.

The theory remains viable, and a few researchers are still working with it, but most are investing their efforts in directions more likely to yield positive results, and more in tune with recent observations.

[Qev]

Heh, it's kind of funny, I wasn't even trying to suggest that neutrinos make up dark matter. Rather, that they played a role similar to dark matter in the past, ie. a (then) unobserved particle that was proposed to account for observations of missing energy.

I'd always thought that neutrinos were disqualified as the main dark matter culprit due to their extremely low mass (despite the enormous quantity of them out there); thanks for enlightening me, Chris.

[harry]

G'day Chris

Neutrinos play a critical part and research in this field has just started.
The question is what dark matter are you refering to.

Dark matter neutrinos 2007 to 2008

http://arxiv.org/find/all/1/all:+AND+20 ... /0/all/0/1

SAO/NASA Astrophysics Data System (ADS)
http://adsabs.harvard.edu/cgi-bin/nph-basic_connect
Search for

http://adsabs.harvard.edu/cgi-bin/nph-b ... &version=1

[Chris Peterson]

Neutrinos play a critical part and research in this field has just started.
The question is what dark matter are you refering to...

You're doing it again- spewing lists of papers that have little or no relevance to the point you're trying to make (if I even understand that point).

There's hardly anything in your references that argue for neutrinos as dark matter. Most show up in the search because they are mentioned in dark matter research.

So to be clear, neutrinos are a critical part of cosmological research. Has anybody suggested otherwise? My point was simple: ten or twenty years ago, neutrinos were seriously considered a viable candidate for dark matter. In the last decade or so, support for that theory has fallen off substantially, as new observations made it much less likely, and provided support for some sort of cold non-baryonic material.

The possibility of dark matter being made up of neutrinos (or partly made up of neutrinos) has not been completely excluded, but few researchers are still working in this direction.

[Nereid]

G'day from the land of ozzzzzzz

Lately there have been a number of papers that have excluded dark matter.

Eg

[...]

It might help the general reader, harry, if you were a bit more precise in your summary ... the only dark matter 'excluded' in your two examples is that in spiral galaxies, and the scope of their 'exclusion' is only rotation curves ... for example, neither considered gravitational lensing.

AFAIK (as far as I know) no papers have attempted to address the several classes of observations for which 'cold dark matter' is used, consistently, as an explanation, from the CMB through large-scale structure to three kinds of observations of rich galaxy clusters to many kinds of observations of individual galaxies (both spiral and elliptical; both normal/giant and dwarf) ... with one exception - various models of gravity that explicitly extend or modify GR (such as TeVeS).

In the case of the two papers you cited, the first clearly fails for everything which traces rotation curves except ISM plasma; the second is based on an idea that was explored decades ago ... and shown to fail.

[harry]

G'day from the land of ozzzzzz

Hello Neried

Those links where posted as an indication that research into neutrinos has not been reduced. Not as a discussion point. I think.

Maybe you were talking about the previous links and these where posted as information and not my opinions.

Although they maybe out of date they are in line with current thinking.

I will come back with update links.

[Nereid]

G'day from the land of ozzzzzz

Hello Neried

Those links where posted as an indication that research into neutrinos has not been reduced. Not as a discussion point. I think.

Maybe you were talking about the previous links and these where posted as information and not my opinions.

Although they maybe out of date they are in line with current thinking.

I will come back with update links.

harry, I was quoting a post of yours in which you said "Lately there have been a number of papers that have excluded dark matter."

In that post you referenced two astro-ph preprints, one by Tsiklauri and one by Banhatti.

Was my comment on your post inaccurate? Did I not quote enough of your post for you (or any other reader) to identify it unambiguously?

My point ("It might help the general reader, harry, if you were a bit more precise in your summary") was not about whether you were posting an opinion or "for information", but that your summary was too terse, to the point of being misleading.

Given your long-time interest in this area of astrophysics, I'd've expected you'd've taken a bit more care to present the material in a less misleading way, especially since it would have taken you a not inconsiderable amount of time to find and select those two preprints in the first place.

Chris Peterson said "You're doing it again- spewing lists of papers that have little or no relevance to the point you're trying to make (if I even understand that point)." Perhaps you'd like to take some time to be a little less terse? Starting with "an indication that research into neutrinos has not been reduced. Not as a discussion point. I think."

[harry]

G'day Neried

Thank you for being so humble.

Its just that I'm reading through so many papers and I see a paper that maybe relevant to the topic, at least an interest in the reading of it.

Ever since you told me to read scientific papers such as ADS, it has been a never ending story, challenging and lots of fun in discovery and learning that I know very little.

It will take me another two odd years to even understand the workings.

If you think any papers are not worth reading, please delete.


OK, I will try to be more care in presenting the information.