Dark matter Definition and 919 Threads

Hello All, Here is an article we have just published on a very interesting development concerning dark matter: http://www.isracast.com/tech_news/061005_tech.htm Comment are most welcome. Iddo

The Distribution of Dark Matter in Spirals Perhaps another 'epicycle' is required? Or is the Halo baryonic after all? Just a thought. Garth

This time the news is that on 21 September this paper was accepted for publication in Astrophysical Journal. It will appear in January. http://www.arxiv.org/abs/astro-ph/0506370 Galaxy Rotation Curves Without Non-Baryonic Dark Matter J. R. Brownstein, J. W. Moffat 43 pages, 7 figures, 4...

could dark matter simply be an error in general relativity or the effect of temporal effects on orbits, ie time is slower the nearer the sun, so the Earth rotates slower on the sun side, and so is pivotted towards the sun(or does this explain gravity only, or maybe the reason objects don't slow...

Hey guys, what is dark matter?what is it made up of and where is it?can any theory explain this? can string theory explain this? so please frendz help me out of this.

http://www.nature.com/news/2005/050829/full/050829-18.html [PLAIN]http://xxx.arxiv.org/PS_cache/astro-ph/pdf/0508/0508572.pdf[/URL]

http://xxx.arxiv.org/abs/astro-ph/0508572 I like the way the title of this paper captures ones attention. For a minute there I thought they had finally found some evidence for string theory. From what I understand they’re speculating on astronomical observations of dark matter, by...

http://www.arxiv.org/abs/astro-ph/0508624 This paper offers a fairly natural explanation for the universality of dark matter halo profiles. In this model the mass accretion history has two distict phases, first a fast phase dominated by frequent mergers of smaller condensations of CDM...

For anyone interested in a recent, state of the union address on dark matter: http://arxiv.org/abs/astro-ph/0508279 The Dark Side of the Universe Authors: Katherine Freese

The new paper is titled General Relativity Resolves Galactic Rotation Without Exotic Dark Matter It is on the arxiv at http://www.arxiv.org/abs/astro-ph/0507619 From the abstract

If weakly acting dark matter does not interact with photons, how is special (or general) relativity applied in its case? Signaling (or lightlike geodesics) would be hard to define where there is no electromagnetic objectivity. I guess this inertness may be a problem in determining a neutrino's...

http://arxiv.org/abs/astro-ph/0507142 Title: Constraints on dark matter and the shape of the Milky Way dark halo from the 511 keV line Authors: Y. Ascasibar (1), P. Jean (2), C. Boehm (3,4), J. Knoedlseder (2) ((1) Harvard-Smithsonian CfA, USA, (2) Centre d'Etude Spatiale des Rayonnements...

There are several scientists (including Stephen Hawking) who made calculations about our Galaxy rotation and mass... The only stable Milky Way construct they were able to come up with had to include in it's calculation the so called "Dark Matter" ... As I am a realist I just can take seriously...

Dark matter drives expansion http://arxiv.org/abs/gr-qc/0506108 Unification of dark matter and dark energy via quantum wave function collapse Authors: A. S. Majumdar, D. Home Comments: 5 pages, RevTex Dynamical wave function collapse models entail the continuous liberation of a...

Why is it necessary to assume dark matter exists in the universe? If we feel that galaxies are rotating faster than it is possible for normal matter to do so, they must have less moment of inertia. This will make their rotation fast. Hence, they should have less mass, not more! I’ve heard that...

I want to know more about dark matter. Please tell me: Why do scientists think that there should be dark matter?

1)Ok.I was wondering ..what happens after we reach singularity inside black hole?...Do we become part of the black hole and strengthen it by increasing its mass in the same amount of volume? 2) Is Dark Matter only confined to the outer stretches of the Galaxy?..or is it also found elsewhere...

I've been reading and posting in this forum for a little while. I've noticed a few things have been mentioned about dark matter, energy, and negetive gravity. I asked my physics teacher about what dark matter was; he said it was basically protons that have negetive charges and electrons that...

When I was doing science fair projects in astrophysics, sometimes I felt like asking my mentor random astronomy questions that I had in my mind. He was a very great man and taught me a lot about astronomy and kept my interest in the subject alive such that I decided I wanted to major in...

Can we detect WIMPs and axions on earth? WIMPs or/and axions are believed to be the basic constituents of dark matter.

Does anyone know of any work that has been done on the possible theoretical physics/mechanics of Dark Matter, for example if Dark Matter cannot lose energy by radiation then it presumably cannot undergo gravitational collapse in the same was as baryonic matter? A layperson's guide would be nice...

I'm not trying to advance a pet theory here .. it's really just a question. Why don't physicists serious consider the possibility of energy/mass contained in the false vacuum as the source of Dark Matter? At least I've never heard of a serious one in these terms. Real particles and their...

Can and do they exist primarily separate from ordinary matter, and how might they be detected (e. g., gravitational lensing, Newtonian mechanics)?

I was wondering what kinds of experiments we are doing to find out what DARK MATTER and DARK ENERGY is and where there being preformed

A "Weyl" theory of dark matter http://web.mit.edu/people/cabi/index.html by Hung Cheng of MIT, showing that if physics is locally conformal (independent of scale choice) then there is a vector particle he calls S which couples to a scalar particle like the hypothetical Higgs, or to a tensor...

[FONT=Franklin Gothic Medium]Hey ! So we found some of that dark matter, :smile: woohoo ! But honnestly, I thought their had been a misprint on the Chandra site when I read that they calculate the temperature of these webs of particles to be 1 000 000 °C :bugeye: ! ? ! ? ! ? ! How the...

In another thread we discussed the nature and extent of the Giant Galactic Blobs!, and the nature of Dark Matter. I advocated a baryonic nature of most or all of the DM following the “Freely Coasting” Cosmology model. The question it raises is, "What form does this baryonic matter take...

Bekenstein just posted a new paper on his relativistic MOND which obviates dark matter http://arxiv.org/astro-ph/0412652 An alternative to the dark matter paradigm: relativistic MOND gravitation This is a followup of an earlier Bekenstein paper which was published in Physical Review...

http://arxiv.org/ftp/astro-ph/papers/0212/0212251.pdf

Another log for the controversy campfire http://arxiv.org/abs/astro-ph/0405282

If dark matter has mass, interacts with gravity, and is pervasive then why isn’t it gathering at points of mass and turning all the suns into black holes?

Could hot dark matter be cold dark matter? In other words did hdm cool and become cdm? And could hdm moving at or close to the speed of light exist beyond the most distant detected galaxies?

Gravitational Theory, Galaxy Rotation Curves and Cosmology without Dark Matter J. W. Moffat http://arxiv.org/abs/astro-ph/0412195 "Einstein gravity coupled to a massive skew symmetric field F_{\mu\nu\lambda} leads to an acceleration law that modifies the Newtonian law of attraction between...

General Relativity GR, and Loop Quantum Gravity LQG as well, says that space is derived from the gravitational field of matter. But the total matter in the universe is constant; whereas the space of and the amount of Dark Energy in the universe is growing. It is supposed that most of this...

Authors propose solution to dark matter and alternative to MOND. Higher Order Curvature Theories of Gravity Matched with Observations: a Bridge Between Dark Energy and Dark Matter Problems http://www.arxiv.org/abs/astro-ph/0411114 Higher order curvature gravity has recently received a lot...

I admit that dark matter is apple pie and motherhood. I love Dark Matter just like you. But this paper has been accepted for publication in Physical Review Series D they did not post the preprint at arxiv until it had passed peer review and been accepted. this is a 72 page paper. we cannot...

http://www.bell-labs.com/news/2000/may/11/1.html has a number of links (bottom of the page) very relevant to observational studies of the distribution of dark matter. In particular, the last three links: http://dls.het.brown.edu/, a programme to create maps of the distribution of dark...

I been thinking... ...anything falling into a black hole and assuming it gets reduced to it's basic "string" then by way of the spiralling effect of the black hole in an ever decreasing vortex becomes a very long very dense connection of strings only a Planck unit in diamater but infinitely...

Fantastic amount of information contained in this paper: http://uk.arxiv.org/PS_cache/hep-ph/pdf/0404/0404175.pdf Its long, but everything you 'dont' know about Dark Matter is contained in this interesting overview. Takes a while to load because of its size, but its well worth it, authors...

I'm reading Hawking's take on ground state energies never being zero, and he adds an interesting point. He said based on the casimir effect the denisty of ground state fluctuations (wavelengths) are less by a finite amount between the plates, causeing them to draw together. To me this explains...

Are electron clouds formed because the electrons are traveling near the speed of light? If so, why is a "cloud" formed --- a colloid, that is. If it is possible to form a more uncommon type of matter like a colloid by traveling near the speed of light, could you possibly form dark matter by...

Could anybody list (and write a few explanatory words about) the various theories which explain the origin of the dark matter and the dark energy? Thanks!

My understanding is that dark matter surrounds a galaxy in a spherical formation. What I don't understand this type of dark matter can explain the non-Kepplerian rotation of the galaxy. According to Gauss's law, in a spherical shell, only the mass inside the orbit of a body has a net...

dark matter --- dark energy Can anyone explain to me the difference between dark matter and dark energy ? What are their proper relations to the expanding universe? Dark matter should be taken into account because we know not enough matter that can be held responsible for keeping...

Why does light have a speed? Why does Gravity (Gravitons) have a speed? There is nothing to slow them down... (Or is there!?) E.g. Sounds in water have a speed because of the matter they travel through. Light traveling through different materials will be effected on how fast it can travel...

This is just an idea but if galaxies have or develop a black hole in their center couldn't it be possible that darkmatter uses the electromagnetic field of the black hole to keep the galaxy in place and also keeps it from colliding with another galaxy. I can't really explain what i am thinking...

If Dark Matter was the mirror twin to Dark Energy, then normal matter would be siamese twins?

i'm interested in any alternative theories re: dark matter...is it possible that we simply have misunderstood gravity at these distances? it seems strange to me that we look for symmetry in the physical laws and so we see something we can't explain using the law of gravitation and our...

evidence against existence of dark matter?? Hi have there been any recent publications that u guyz may have read that are against the idea of dark matter and have other theories on wot keeps galaxies in orbit.? I really need ure help coz its for an essay that i have been working on. cheers.

Heya! I need some good links to articles on dark matter that are easy to understand and are worth reading. Stuff on neutrinos,, hot dark matter, cold dark matter...and mass to light ratios. tanxy.