Dark matter Definition and 919 Threads

NASA just had a press release today of new evidence that supports the presence of Dark Matter. I think this would be the most direct detection so far if verified. http://www.nasa.gov/home/hqnews/2007/may/HQ_07114_Hubble_Dark_Matter_Rings.html We still have to wait for the publication of...

I will be writing my final exam tomorrow evening, and I am currently stuck on the following practice problem. It would be very nice if someone could help me out and I will remain eternally grateful for your help! 1) (Multiple Choice) Which of the following statement(s) about Cold Dark Matter...

I'm doing a project on dark matter and I've found some good information but I still haven't found any related mathematical equations.. are there any not to complicated ones i can relate to it??

Would there be any way to discover dark energy, dark matter, if the only observable body was the galaxy you lived in?

My dream engine, needs a dark matter governor to prevent it exceeding its designed rpm limit, unfortunately no one makes them yet. It will produce dark energy as the motive power, but alas the formula for its production, or its existence is not known. It will, hypothetically, if it runs...

An easy one. How does dark matter clump together,is it possible for dark matter to form a sun.

Hi everyone - I'm having some trouble with the real concept behind "degeneracy" of dark matter. I've heard of degeneracy before in maths (eg. a 'point' is a degenerate 'circle'), and in physics (eg. energy level degeneracy in atom shells), but I don't quite see how either of these work when...

Hi, Many astronomers believe that there is no center to the universe. So where ever you go, you would approximately see same amount of matter (stars galaxies etc) around you. So we can assume that there won't be net gravitational effect on anybody at all the places in the universe...

Ok, one more question. (The responses to my first two far exceeded my expectations, by the way. This forum is clearly populated by some very well informed and passionate people. Thanks.) Is there a detectable effect of DM on the motion of planets in our solar system? If not, why not?

I have two questions. They are related, but different enough that I think it makes sense to raise them in two separate threads. The first concerns 'dark matter'. The NYT article is a good example of what is bothering me: https://www.physicsforums.com/showthread.php?t=160464 (Please...

I'm putting together a slideshow about dark matter for my colleagues and was wondering what would be good reference material to fall back on other than stuff like Douglas Clowe et al. Any "start here" links along those lines?

Any reason why cold dark matter isn't just ice? All the chemical reactions going on out there since the creation of the universe, would have created a great deal of water. Also would fit with comets being made of the same stuff. Just wondering... NMK

Does Andromeda contain dark matter? Is the newly discovered halo able to account for the rotation of the galaxy?

http://www.esa.int/esaCP/SEMZ6GSVYVE_index_0.html Go read it while I try to comprehend how they managed to map the dark matter in the universe by studying a relatively tiny part of the sky.

When i read "Alternative" i immediately thought "crackpots!", but then I read on and found out they're on to interesting stuff. http://www.physorg.com/news85310822.html

So I was googling around and I happen to see several references to MOND theory, Modified Newtonian Dynamics. Anyway, it proposes that there is this other new constant a_{0} that is a very very very low acceleration that exists. Basically, as far as I can tell so far the whole idea is that...

What is the evidence in favor of dark matter? How does does this take into account baryonic and non-baryonic matter?

Here is the latest in the 'bullet cluster' series on evidence for the existence of dark matter: http://arxiv.org/abs/astro-ph/0611496 Catching a bullet: direct evidence for the existence of dark matter Authors: D. Clowe (Ohio University), S. W. Randall, M. Markevitch (CFA) Comments: 4...

I have been interested in astronomy since I was two years old (I knew the names of all the moons of Uranus, the fact that there were only 15 back then was irrelevant :P) but even now at nearly 16 something confuses me: Planets orbit the Sun (or stars orbiting a galaxy, or moons orbiting a...

Dark matter plays a significant role on the relation between orbital radius and velocity of stars within galaxies. Does it, however, have a theoretically calculable and eventually measurable effect on planets, like those of our solar system?

Hi. Couldn't dark matter be confirmed with the gravitational lense effect? Shouldn't we see a difference in the lensing effect that is not accountable to the traditionally considered visual mass?

Has the discovery of dark matter and dark energy demolished our chances of finding a "theory of everything" any time soon - as I understand it string theorists say they are close(ish) to finding such a theory, but all our theories to date (including quantum mechanics and special relativity as...

http://www.physorg.com/news77190620.html

I don't know if this belongs in Astronomy or Cosmology, mods, move it if you see fit. As far as I'm aware the idea of Dark Matter was introduced because of the rotation of galaxies. Closer to a galaxy's centre matter should move faster because of the stronger gravitational pull, and further...

Recently, astronomers have reported the observation of what they think of as dark matter in two colliding galaxies. They used observations from two sources: the Chandra X-ray observatory for the distribution of visible matter, and a gravitational lense for the distribution of...

Recently reported observations of the Bullet Cluster of galaxies (see http://www.nasa.gov/centers/marshall/news/news/releases/2006/06-096.html ) claim proof that what I'll call Exotic Dark Matter (EDM) exists. Previously the most direct evidence for lots of some sort of Dark Matter (DM) was, as...

http://www.nasa.gov/home/hqnews/2006/aug/HQ_M06128_dark_matter.html press conference Monday 21 August CHANDRA team has been watching the highspeed collision of two clusters of galaxies they can see the GAS of the clusters colliding and getting hot so it radiates Xrays they may have also seen...

http://www.nasa.gov/home/hqnews/2006/aug/HQ_M06128_dark_matter.html http://asymptotia.com/2006/08/15/watch-that-space/ http://www.cosmicvariance.com" 's Sean Carroll is one of the briefing participants.

http://arxiv.org/abs/astro-ph/0607621 An interesting look at the equiptment in use to detect DM.

Berkeley writes : " Note that the dynamics of the Universe are not determined entirely by the geometry (open, closed or flat) unless the Universe contains only matter. In our Universe, where most of Omega comes from dark energy, this relation between the mass density, spatial curvature and...

Can any, qg or string theory reproduce dark matter ?

i want to know, do we have a physics of this undefined term? as far as i can tell, the hypthesis is that dark matter differs from "ordinary" matter by the fact it doesn't ommit light, if that's right beside the point of how can you find it with astronomical tools (which depend mainly on light...

What chances would you give the different candidates to actually make up (the major constituent of) the dark matter? That is, if you were a bookmaker, what chances would you find appropriate? I'd find it interesting to see what you all think. At the moment I'll go with the following: LSP...

There are several pieces of evidence to suggest that DM is a real artifact of the universe. 1. Nearly flat rotation curves of spiral galaxies suggest they are embedded in a massive unseen halo of some kind. (Although the mass of these haloes may be affected by GR gravitational effects and...

Hi Friends, I just want to know how many of you believe that there is dark matter and dark energy in the universe and how many of you believe that there is something wrong with our understanding of gravity.

A recent study using the VLT array has measured the temperature and size of dark matter clumps. Interestingly enough, the study has not yet been submitted to Arxiv, but will probably appear within a week. It is expected to be one of the most important papers in 2006. Here is a teaser: Dark...

http://arxiv.org/abs/astro-ph/0602519 Authors: H. Balasin, D. Grumiller Comments: 11 pages revtex4, 4 eps figures Report-no: LU-ITP 2006/002 Exact stationary axially symmetric solutions of the 4D Einstein equations with co-rotating pressureless perfect fluid sources are studied. This is of...

This should help clear up the mystery. What do you think? DARK MATTER EXPLAINED [Nereid's note: please check your mailbox, soliasenberg, for why your post was deleted.]

http://news.bbc.co.uk/1/hi/sci/tech/4679220.stm Gerry Gilmore's Cambridge team did a survey of clouds of dark matter, using several telescopes including VLT in Chile. they found no blobs of DM smaller than about 30 million solar masses, or less than 1000 lightyear diameter. They inferred...

Black holes are constructed from ordinary matter. Their charge to mass ratio, a measure of photonic interaction, is comparatively small. They have been indirectly (gravitationally) observed. They are common in the halos of galaxies where older, Population II stars have hereto collapsed, and...

Do dark matter bend light? Have they found dark matter?

I apologize in advance if this is the wrong forum for this thread... My overall question is: What specifics, if any, do we know about the "dark" stuff - ie dark energy and dark matter? Specifically: Do we know anything about what the darkstuffs are made of (either experimentally or...

there must be a lot of ways already proposed to do this. can anyone list those considered most promising? has this been the subject of a thread already today I saw this paper which claims to suggest a way to observationally distinguish MOND from DM-----to tell which is right. I think...

Google scholar has 651,000 results for dark matter and 521,000 results for dark energy, more than i could read in a life time, can anyone suggest the hot pappers on these subjects.

I would like to explore the possibility that the gravitational effects of Dark Matter might possibly be accounted for by the Unruh effect applied to the acceleration of gravity. The Unruh effect predicts a temperature associated with any acceleration. And an energy density can be found for this...

Just realized that this paper hadn't been posted here, and thought everyone might like to see this. http://xxx.lanl.gov/abs/astro-ph/0507619 Very interesting findings, not too hard to read. The ultimate point is that, traditional computer simulations of galactic rotation are done using...

I recently made a post here asking questions that where clearly rediculous. I guess I need to be more obtuse. The reason I asked it here is that I'm looking for any possible way in which the 'tornado-like' rotation of galaxies could be explained by any kind of possible atomic structure in 3D...

Can someone explain to me what is it or what is theorized to be dark matter. What effects does it have in regards to the cosmos. Thank you, vm

new study shows Dark Matter mat not exist? Relativty explains it? Look here http://www.space.com/scienceastronomy/051010_dark_matter.html" Is this valid reasoning? I noticed it hadn't been submitted to peer review.

Which alternative do you think is the most likely to solve the Dark Matter problem?