Dark matter Definition and 935 Threads

So I'm running a superhero game on another forum and I am trying to keep comic book physics to a minimum. Problem is...I've never taken a physics class (I'm a high school student, I've taken Biology and Chem but Physics is next year). I was wondering how dark matter and dark energy work and...

http://www.space.com/scienceastronomy/071029-mm-mog-theory.html

Does anyone know if gravitational lensing confirms the existence of Dark matter?

No, not really, however my question is why has not dark matter been discovered, observed directly in the cosmic background radiation? Reference: http://en.wikipedia.org/wiki/Dark_matter

"black hole the video". see what you think. go to a google video window. video feedback loop shows a black hole in real time. is the center rotation dark matter?

Why does cold dark matter imply a bottom-up scenario of structure formation? and why does hot dark matter imply a top-down scenario of structure formation? is it simply because cold dark matter is slow moving (non-relativistic) and slow moving things are more likely to clump together to form...

New Scientist has a page on a new theory, proposed by Andrew Liddle, says that maybe one particle is responsible for inflation and dark-matter, its called the inflaton It goes on to say that Liddle and his colleagues realized that if some inflaton particles survived after the intense burst of...

A nice review of Dark Matter and Dark Energy, including discussions of the CMB and Inflation, arrived today at the arXiv: http://arxiv.org/abs/0706.2986 I think some people here would find it quite interesting.

Hi everyone, I have just read an article about the discovery of a ring of a dark matter. In fact I do not understand this matter very much, except that it has great gravitational field in space. Can anyone explain shortly about that or just give me some web links that I can read about that...

hi and yes i have read all other threads and news about the discovery of ring of dark matter. i was just wondering would the ring of dark matter would consist of the same composition (materials, matter etc)? because i was just wondering...if the collision of 2 galaxies clusters and...

Could Dark Energy and Dark Matter be ...? Time? I am sure that there is hundreds of reasons why this could not be possible but, it seems to me that there is some kind of synergy in this hypothesis. Imagine for a moment that time is a form of energy that we have not yet managed to quantify...

I've heard much talk of dark matter and the universe being more massive (according to calculations) than it should be given the amount of observable matter in it. Or something to that effect. But I am thinking that since black holes pretty much consume matter and gain mass and are...

this just out: a survey of efforts to detect DM particles. http://arxiv.org/abs/0705.3345 Direct Dark Matter Searches N. J. Spooner Submitted to JPSJ, 20 pages, 5 figures "For many working in particle physics and cosmology successful discovery and characterisation of the new particles that...

I was wondering, if dark matter (DM) halos are spherical in nature and increase in density as a function of distance from the galactic core, why does the density drop off so suddenly and why would stars on the edge of a galaxy feel an inward pull? To elaborate on the 2nd question, if DM...

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?

Dark Matter Mapped by Hubble (space.com article): http://www.space.com/scienceastronomy/070108_mm_darkmatter_map.html This is a very interesting article on Dark Matter and there are nice pics showing its clumpiness at varying distances from Earth. According to the last paragraph of the...

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.