Dark matter Definition and 920 Threads

This is probably a stupid question with a very simple answer but I hope someone here can help me, I'll try to explain myself as best I can... I was thinking about spacetime being elastic, if I place a large mass on the elastic sheet it bends around it, when i place a second mass on the sheet, as...

If we can not use gamma rays to detect Dark Matter what can we use? http://www.sciencedaily.com/releases/2016/02/160203110928.htm Studies by two independent groups from the US and the Netherlands have found that gamma ray signals from the inner galaxy come from a new source rather than from...

Dear all, I am new in the field of galaxy formation, so I am sorry if my questions are a bit simple. -what does virialized halo mean? does it mean they obey the virial theorem concerning their kinetic and potential energy? \begin{equation} 2<T>=n<V> \end{equation} -Why should the halos be like...

Orodruin submitted a new PF Insights post Knut Lundmark and the Prehistory of Dark Matter Continue reading the Original PF Insights Post.

Chalnoth posted this in another discussion: "The cosmic microwave background is almost impossible to explain without dark matter (there is clear evidence of a component of matter that feels pressure, and a component of matter that does not feel pressure, which can only be true if that matter...

Okay so I've been searching the internet for this answer, but I have not yet found it. What is dark matter/dark energy? What is the difference between the two? On a website that I was on earlier, someone described dark matter as a cluster of dark energy, which would make no sense because matter...

I'm trying to understand the mechanisms of the anisotropies in the CMB. The general idea is that there are fluctuations in some field (e.g. inflation) and the baryonic and dark matter rush into the space compressing the fluid. The photon energy pushes back on just the baryonic matter while the...

I am doing my undergrad research on Dark Matter and Dark Matter but have only few links of sources. Are there any online info-stores where I can get most of the discovered information on them. All related research papers and the different properties discovered about Dark Matter and Dark Energy...

Large Underground Xenon dark matter experiment and LHC have reported a null result on searches for dark matter, with new bounds. What are the implication of these new bounds on neutralinos and LSP?

Very roughly put, my limited understanding is that dark matter is postulated because of effects seen in the geometry of space similar to those created by matter. Is it necessarily true that there is some form of matter causing that spatial distortion? Couldn't it be postulated that there are...

Why do scientists think that dark matter annihilates just like antimatter? How is it that dark matter during annihilation can produce light when it cannot emit or absorb light itself?

If luminosity increases, hypothetically, for a given galaxy, would the percentage of dark matter in that galaxy be smaller? What if the colors of the stars were to turn redder? I was thinking if the luminosity were to increase, that would mean the percentage of the normal matters increases...

How do we know that the effects of "dark matter" are not merely a failure of some other aspect of general relativity? Could it be that it is not matter at all but instead some placeholder for another aspect of our universe, or is it proven that there must be some form of 'matter', so to speak...

WIkipedia says antineutrinos are candidates for dark matter. What does this mean? How is it a candidate, and how could an antiparticle even exist in large quantities in the universe? Or is it only meant to be a small piece of problem?

Hello Friends, I, Arnendu Barman, is a high school last year student. I have much confusion in Dark Energy and Dark Matter. Actually I do not understand them and I also have problem on Negative Mass. So friend please help me . Thank you...

I recently read this article about how the Higgs Boson could decay into Dark Matter particles. Why is this not being taken seriously, there must be something, and I am not a physicist, just a ninth grade student, so why is this either a good theory or bad theory? Thanks in advance! Here is the...

According to this paper not only is Dark Energy part of the field Dark Matter is too http://www.indiana.edu/~fluid/paper/HMW15.pdf In summary, we conclude that the dark matter and dark energy are essentially gravitational effect generated by the gravitational potential field gµν, its dual...

http://arxiv.org/pdf/1507.01019v1.pdf What do you think? Not published yet, but one of the authors is a postdoc at Princeton and the other a Princeton PhD and prof at U Penn so they might know something. As far as I know, the superfluid dark matter theory is deprecated because models of the...

Is this a break though or just hot air? http://arxiv.org/pdf/1510.05534.pdf We do not claim that the Mestel (1963) disk is the answer to establishing the universality of flat rotation curves in galaxy disks; only that it has always been a telling clue that gravity does not pull the strings and...

I read dark matter makes the stars in a galaxy to move about a same orbital velocity. Why isn't this applicable to our solar system?

http://w.astro.berkeley.edu/~mwhite/darkmatter/essay.html, A good overview of dark matter. Quote. The density of matter in the solar neighborhood is measured by sampling a uniform population of luminous stars that extends well above the disk of the galaxy. The average velocities of the stars...

As I understand it, the statement of the horizon problem assumes that the uniformity of the CBR measured at opposite directions in the sky needs a mechanism to create this uniformity. I also understand that many cosmologists do not share this assumption. The purpose of this thread is to seek...

Will particles that don't interact with normal matter (dark matter for example) emit cherenkov radiation (if light in that medium moves slower than that particle) ?

Hello everyone! I'm a freshman intended physics major at UC Berkeley, and I am taking the honors mechanics course. It is really rigorous, but I do feel like I'm learning a lot. My strengths are Newton's Laws-based questions, and my current weakness is setting up differentials. I love...

Is the presence of Dark Matter noted in Milky Way or somewhere around solar system??

I'm wondering if someone can give a more detailed history of Dark Matter than what I've found on Wikipedia. How did Fritz Zwicky determine that a galaxy was in 'equilibrium' given the uncertainty of a line-of-sight measurement of velocity? How did he determine the mass given the variables of...

I have been looking into Dark Matter recently and how we know really little about it to even try to identify what it is clearly. But Dark Matter obiously has mass which means that in some way it must be interacting with the Higgs Field. So could studying the Higgs Boson and comparing its...

Does the E8 theory that offered and posted by [FONT=Arial]Antony Garrett Lisi,can explain the qualities and the source of the dark matter and dark energy in the universe?

As observed in published space maps, I have noted that dark matter is present only in those region which already have visible mass around them. Is this really a fact or just my wrong belief?

i was thinking about the Higgs Boson analogy that was put forward to help describe how it works/interacts to produce mass, of a very famous person walking into a party, everyone gathers round impedes progress, high interaction with Higgs field and particles therefore high mass, and then a less...

I thought this paper is worth citing it gives a good overview of Dark matter, it maybe a little out of date but it is still a good readhttp://arxiv.org/abs/1006.2483

We know that in the Baryogenesis happened a asymmetry between baryons and antibaryons.Here Is matter only BM(baryonic matter) or BM+DM. If its only BM so we have extra DM which its a matter.So the Baryogenesis solved ? (Here of course it can't be solved cause there's a big difference between...

Is there any dark matter where no baryonic matter (which here the galaxies).I mean are we observe dark matter only around the matter ? Or dark matter can be anywhere (In empty space which there's no baryonic matter around)

I am doing research and I need to find the dark matter density of Galaxies or dust clusters (It can be any type of thing) which the distance from Earth will be ≅4000 Mpc.Here the picture Think the radius of sphere.

I am currently an NE major, but I am on the verge of switching to Physics at the start of my 2nd year. I have received B's in Calc 2-3 and in Engineering Physics I ( a massive weed out course) 120 students started out in that class, only 26 are registered in the 2nd Engineering Physics class(...

Hey, my name is Roy and I'm new to Physics Forums. I'm a retired medical and aerospace test engineer, now currently a freelance artist (kind of opposites right?) and I joined Physics Forums to hone my understanding of physics and ask the right questions in an ever expanding field of inquiry...

Some times I think space and Matter most to be different on others places and maybe equations need to be fit, but to find dark matter, what do we need to have here?

Dark matter particle candidates are being searched at CERN and the various dark matter models are being probed by cosmological simulations. The usual way to probe models via cosmology is to plug a candidate into a cosmological simulation and then compare the results with observations. Yet...

There are not found the WIMPs until now. Ma be the effect of Dark Matter is because of a defect in topology otherwise than time dilation in General Relativity. The lattice gauge theory formulated on a grid or lattice of points in space and time is successfully used in the quantum...

I was searching Dark Matter and I found this site is that can be true ? Dark matter can be a act like a pion ? http://right.is/space/2015/07/deja-vu-new-theory-says-dark-matter-acts-like-well-known-particle-2117.html

This paper, http://arxiv.org/abs/1507.06282, The Duhem-Quine thesis and the dark matter problem, may be of interest to those curious about how and why dark matter has gained general acceptance by cosmologists

In general photons are not candidate for dark matter. From the other hand stars constantly change matter into radiations (photons among them). And we can not measure radiation that does not hit us (although we can try to calculate it because radiation from star goes with same intensity in each...

In wikipedia says Physical baryon density: ##Ω_bh^2=0.02230±0.00014## and Physical dark matter density:##Ω_ch^2=0.1188±0.0010## Matter density:##Ω_m=0.3089±0.0062## so If we collect baryonic matter density and dark matter density we...

<<Mentor note: Thread split from Is Dark matter homogeneous in Universe?>> Not to be rude... but how do you know it even exists? Dark matter is a place holder used to make a hypothesis work mathematically with actual observations. Dark energy... Ditto. And the original hypothesis itself is...

I learned that dark matter distrubition is homogeneius and isotrophic in cosmic scales. I searched some galaxies dark matter distrubition.And I am actually suprised. Why cause every galaxy has a different ratio of dark matter baryonic matter distrubition. In cosmic scales baryonic...

Is Dark matter homogenenius in Universe ? I don't think so but I don't know any idea about it. Thank you

This the best description of Dark Matter i have come across, it uses the LCDM and MOND to create a best fit model. arXiv:1507.03013 [pdf, other] A Dark Matter Superfluid Justin Khoury Comments: 8 pages. To appear in the proceedings of the 2015 Rencontres de Moriond, "Gravitation: 100 years...

Are there any high resolution observations of the gravitational lensing by dark matter, good enough to determine if dark matter is clumped or spread out at small scales?

I've been reading on dark matter and I've never seen a satisfactory explanation as to why dark matter is expected to interact with the weak force. From what I gather, the only reason it's expected to do so is based on assumptions that dark matter had to be created after the electroweak epoch...

I have found this paper, it seems interesting although i haven't read it all yet arXiv:1507.00460 [pdf] Dark matter, Mach's ether and the QCD vacuum Gilles Cohen-Tannoudji Subjects: History and Philosophy of Physics (physics.hist-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)