Dark matter Definition and 935 Threads

Hello, I am not quite certain if I have properly placed this query in the correct forum. I am currently reading this article on dark matter http://pdg.lbl.gov/2013/reviews/rpp2012-rev-dark-matter.pdf In the first paragraph, the author states, "This leads to a lower bound on the DM mass...

Does space plasma explain dark matter? I have read about how Voyager 1 showed that there was different density in between our solar system and other galaxies. Doesn't the existence of space plasma then explain that the matter we cannot see is in fact space plasma? I really feel as though I am...

Hi, i got interested in the dark matter, rather than dark matter is another potential force/particles than gravity to create the galaxies what other influences it does that we are currently aware of? Thanks (Keep it simple please, high school student)

Hello, I found same number of arguments and observation regarding dwarf galaxies which supports mond (modification of Newtonian dynamics) and generally same number of arguments and observational support for dark matter so why large number of physicist community is in favor of dark...

Hi, I recently read the following article http://arxiv.org/pdf/0805.2895v4.pdf which deals with dark matter scattering and I have difficulties in deriving formula (1). The problem is the following, we have a nucleon (mass m1, velocity u1) scattering from a dark matter particle (mass m2...

Dark Energy is said to be present in order to drive the observed acceleration of the expansion of the universe and Dark Matter is hypothesised to be present to drive observed gravitational effects. Would a large mass of dark matter distributed around the outer parts of the universe have the...

The IceCube detector in the deep ice at the south pole has seen two instances of 1015 eV neutrinos. These are said to be the highest energy neutrinos so far seen. http://resonaances.blogspot.com/2013/09/storm-in-ice-cube.html What process could have launched such high energy neutrinos? It has...

could dark matter be negative pressure caused by the stretching of the fabric of space by an expanding universe?

Hello, all! I am no physicist, so please bear with me. I just read an article that stated that dark matter comprises over 80% of the universe. If this is true, why is it so hard to find? With that much stuff, you'd think we'd be swimming in it.

Are photons capable of interacting with particles with no charge. And if not, is it possible that that's the reason dark matter has so far eluded detection: because it has no charge?

We know that DM interacts gravitationally with ordinary baryonic matter, so we should assume that any DM particles close enough to a black hole will also fall into it, shouldn't we? If so we should assume that black holes must have some DM inside them, perhaps impossible to estimate in which...

Hi everyone, i was thinking this. I saw in here someone said that, our heads atoms are osscilating with high frequency than feet. Since aftee seeing it, i was thinking if every atom osscilating, is that dark matter are not osscilating? What do you think?

Is anyone familiar with a $$ SU\left( 3 \right) \otimes U \left( 1 \right){}_d$$ or $$SU \left( 3 \right) \otimes SU\left( 2 \right) \otimes U \left( 1 \right)_d $$ model? Kind of what I'm currently interesting in working with, but I don't have access to anything other than the arxiv.cheers.

Any comments on the recent N. P. Pitjev and E. V. Pitjeva paper: Constraints on Dark Matter in the Solar System arXiv: http://arxiv.org/abs/1306.5534 MIT Technology Review article...

I have recently been quite impressed by Mannheim's work on Conformal Gravity. He claims to reproduce the rotation of a sample of 141 galaxies without any need of Dark Matter. In particular, in 1211.0188 its predictions seem to match extremely well to the experimental data. Galactic rotation...

According to the theory of relativity, the universe should expand from the center (place of Big Bang) with a maximum possible radial speed close to the speed of light c. So, the galaxies and intergalactic matter moves with a radial speed close to the speed of light too. For instance, this allows...

Greetings to all, A little information yo provide context to my question. I'm 16, and a junior in high school and I'm attending an astronomy camp on kitts peak doing research projects with the large telescopes. While researching possible projects on that particularly interested me was...

Hello all, I am still an undergraduate, but I would like to ask a really naive question. From a cosmological point of view, does the necessity for the introduction of Dark Matter and Dark Energy in order to satisfy our current models of prediction mean that our models are fundamentally...

Why do we talk about dark matter rather than dark mass? Where does the necessity for matter stem from?

Weinberg's dark matter idea re "fractional cosmic neutrinos" http://arxiv.org/pdf/1305.1971v1.pdf http://arxiv.org/abs/1305.1971 Goldstone Bosons as Fractional Cosmic Neutrinos Steven Weinberg (Submitted on 8 May 2013) It is suggested that Goldstone bosons may be masquerading as fractional...

Hi I rarely have a background in physics (yet!) But based on my popular knowledge I understand that the Universe is 'expanding' in a loose sense of the word - which basically equates to the fact new space is being created all the time which in turn resembles a Universe where the distances...

"Normal" matter makes up about 5% of the mass/energy content of the universe. From studying this 5% we have discovered 4 fundamental forces and numerous fundamental particles. When I read things about dark matter and dark energy it seems that each is assumed to be a single class of phenomena...

Did The Dark Matter Really exist ? did we have an evidence ? and What is the compositions Of The Dark Matter ?

In referring to the recent results of the AMS experiment in the ISS: http://physics.aps.org/articles/v6/40 I'm still left wanting of understanding why the presence of an excess of positrons infiltrating the device isometrically indicates a presence of dark matter and tells me something...

The speed of light in a vacuum is the universal constant c. The speed of light in a medium is something less than c; let's call it s. Has the positive difference (c-s) been observed as light travels through ordinary matter in space such as gaseous nebula or plasma nebula? If no, is it...

How is the search for dark matter, dark energy and gravitational radiation going, as far as i can make out there has been no direct detection and they remain conjectures

Is dark matter dark because we hav never measured it directly on Earth with the atom? John

Interesting news on Dark Matter, I had no idea this experiment was being carried out: http://news.yahoo.com/hints-dark-matter-possibly-seen-190603469.html

First off, I'm not a physicist (as I'm sure is evident by my multi-part question), but I'm hoping someone will be kind enough to explain this in basic terms. Part the first: I'm wondering if someone can explain to me in layman's terms why the speed of light is essentially the universal speed...

I understand there are no friction forces to slow it down but there are other means of dissipating kinetic energy. Every time 2 dark matter particles come close enough to interact gravitationally there should be some exchange of momentum. If there is a cloud of dark matter particles, such as...

I know light behaves oddly compared to normal matter, I haven't really delved into the math of GR, and that's why I'm here to ask these questions. 1) If all of our observations of the universe are based on light, what determines that the speed of light is the maximum velocity? I'm sure its...

Remember this article gang? http://www.cbsnews.com/8301-205_162-57569883/possible-discovery-of-dark-matter-to-be-announced-soon/ This came out Feb 17th, and we were promised an "unveiling" in about two weeks... They said this because it seemed as though they pretty much "had it" since...

If dark matter is real matter out there in space, it must be absorbing photons from adjacent stars and other bodies. Also, by definition, it is not emitting any radiation, so it must be inexorably heating up. Is this sustainable, or will it cause some sort of explosion or start the body on an...

A positive value for the cosmological constant was found by the studies of Adam G. Riess et al and Pearlmutter et al In terms of Planck units, and as a natural dimensionless value, the cosmological constant, λ, is on the order of 10−122 or 10−29 g/cm3 The cosmological constant has negative...

And within the near-galaxy too. If we can find some in close proximity, there's tremendous potential for research. I found these two conflicting articles: (both a few months apart) Survey finds no hint of dark matter near Solar System Astronomers Detect Dark Matter Near The Sun...

http://science.time.com/2013/02/26/cosmic-fuggedaboudit-dark-matter-may-not-exist-at-all/?hpt=hp_c2 Summary: We love MOND, we're not crazy, honest.

Hi I have a question about a popular science article from BBC, you can ofcourse read the whole article but the part that left me wondering was his which I quoted right here. """Prof Ting said that in its first 18 months of operation, AMS had witnessed 25 billion particle events. Of these...

Anybody have any insight on what this is all about? Looks interesting... http://news.yahoo.com/dark-matter-finally-found-big-news-coming-soon-144840916.html

The so called f (R)-gravity could be, in principle, able to explain the accelerated expansion of the Universe without adding unknown forms of dark energy/dark matter but, more simply, extending the General Relativity by generic functions of the Ricci scalar. However, a part several...

I think that there is mass associated with all dark matter in the universe and this mass is much greater than the total mass of the stars in a particular galaxy. Now, if I were to classify the mass into two categories : 1. visible 2. invisible How would I carry that out ? Is dark...

Can dark matter form planets and dark matter life?

http://arxiv.org/pdf/1301.0952.pdf things you always wanted to know about DM.

"A Vast Thin Plane of Co-rotating Dwarf Galaxies Orbiting the Andromeda Galaxy" Published in Nature 3 days ago. Rodrigo A. Ibata, Geraint F. Lewis, Anthony R. Conn, Michael J. Irwin, Alan W. McConnachie, Scott C. Chapman, Michelle L. Collins, Mark Fardal, Annette M. N. Ferguson, Neil G...

I've seen "dark matter bombs" portrayed in some science fiction movies, but is this actually scientifically plausible? Could dark matter be used as a destructive weapon? What would it do, exactly? Open up a black hole? Anti-Matter could definitely be used as a weapon, but it would take...

The title basically says it all, I'm wondering whether dark matter will allow sound to pass through because if it does, that could lead to being a way how to detect dark matter.

Homework Statement Evidence for dark matter comes from “flat” rotation curves of galaxies. Assume that the observed matter moves in circular orbits about the center of the galaxy and that the velocity of the matter as a function of the radius v(r) is a constant. Also assume...

I am not currently a physics major, just an enthusiast. Hopefully that will change soon. Regardless: I hear physicists talk about dark energy & dark matter very frequently, but I've never actually had it explained in a sensible way. Can you tell me what dark energy & dark matter are as well as...

Hi , I have 1 question , What is the Difference between Dark energy and Dark matter ? I want clearly question . Thanks

I have been researching online, but there are many things I am still unsure of because its hard to find the answers to specific questions. 1.) I know how scientists observe dark matter. They can view its gravitational effects. I want to know exactly how it is distributed throughout the...

Ok so I might sound a bit ignorant, but please bare with me. I have 2 questions 1st I've always wondered how they know that dark matter isn't just a bunch of black holes. I mean couldn't there be a bunch of little black holes created right after the big bang. You have all these particle...