Ok...don't get TOO excited, but I've heard rumors that the DAMA experiment (http://people.roma2.infn.it/~dama/web/home.html) will anounce evidence that dark matter has been detected in their latest run. This is nothing new for this experiment---they claimed before that they had a signal, and most other experiments have not been able to confirm the results. In addition, some other experimental results look to be in conflict with the DAMA data.
We should exclude more trivial hypothesis first, like the concepts of MOND theory based on Universe omnidirectional inflation and the idea, the particles of dark matter are formed by positively charged atom nuclei stripped of electrons. Surprisingly enough, the most trivial models are always tested at the very end.
This would be great. I love Psychics as a subject but it's normally theory are theory and rarely are matters objectively concluded.
Ok just an update. DAMA definitely sees SOMEthing, and in a big way. You can read about how the experiment works, but basically we can imagine the galxy filled with an ideal gas of dark matter. The sun is moving through this gas at a speed of something like 22000 km/sec, and we're orbiting the sun. This means that at times of the year we will see an increased flux of dark matter particles, coinciding to our orbits about the sun. The signal is bsaically a sine wave of dark matter flux. DAMA sees this exactly, and their data set is getting better. Typically, phycists have a rule of thumb: \(3\sigma\) for evidence, \(5\sigma\) for discovery. The \(\sigma\) corresponds to a signal above some predicted background. Their previous results were something like a 4 \(\sigma\) effect, but in the recent paper (this week) they claim \(8\sigma\). So like I said, they see SOMEthing. Now, what you should know is that most theorists don't take this result TOO seriously. DAMA is detecting things in places where other experiments have not seen anything, although I don't know the experiments so well as to make this statement completely rigorous. So there are a some people who think that there is some statistical error that the DAMA people haven't thought of. Essentially we have one experiment that sees something and two or three others that don't. This is coupled with the fact that if DAMA IS seeing something, the current theories that we have are in some trouble to explain it, although it doesn't (strictly speaking) rule out something like supersymmetry or large extra dimensions. So the DAMA people see something, but most of the community doesn't think it's dark matter. And most of the community will continue to be skeptical untill there is some experiment which repeats DAMA's results independantly.
The paper is here: http://arxiv.org/abs/0804.2741 You can see in the charts how good their data is. There is a posting at Cosmic Variance about the results, too : http://cosmicvariance.com/2008/04/21/guest-post-juan-collar-on-dark-matter-detection/ by a dark matter experimentalist at Chicago. He echoes the skepticism that I mentioned in the last post.
That's my girlfriends name!! Please Register or Log in to view the hidden image! Please Register or Log in to view the hidden image!
Wow! That guy (Juan Collar) is a *brilliant* writer. He should write popular science books, or at least magazine articles.
I wouldn't get TOO excited just yet. Read the Cosmic Variance posting...it seems that the DAMA people have been less than forthcoming with their error analysis.
What are the properties of dark matter? Can we get more specific in that it is like nothing we have seen before. And we probably could not see it. It is weakly interactive. So could we pass right through it? Would it be dangerous? If I had a bottle of dark matter what could i do with it?
Nothing. Since the DM is not interacting, it wont stay in the bottle. The only interaction it has with other matter is gravitation. They apparantly dont stick together and form clumps of dark matter, so the gravitational interaction then only work over large distance scales. Since they don interact in other ways, they can do no harm.
Weakly interacting means it interacts with normal matter through the weak nuclear force, in addition to gravity. Well, the dark matter particles don't seem to 'stick together', but they do clump around galaxies and other matter. The halos, and other clumps, have been detected by micro gravitational lensing, the gravitational effect on light that passes through the clumps. The effect allows astronomers to 'map' where the dark matter clumps exists and a rough outline of the shape of the clump.
You sure? Any lit I may read (without to much math please) I thought that there was no interaction hence no detection other than gravity. With clumps I meant somethingh like dust particles and small planets.
I'd still say that dark matter is ice crystals, very tiny ones, for from where else does water come from?:shrug:
Ben is right. I believe that the DAMA-LIBRA project was trying to detect dark matter particles through collisions caused by the weak nuclear interaction.
In general, no, because dark matter isn't THAT massive. Some people think that dark matter could actually be really small black holes, but these people are very few in number and their arguments aren't very convincing. Except that there are very good astrophysical bounds that say dark matter has to exist BEFORE there is any water in the universe. (See, for example, the WMAP data.) The interactions that DAMA is looking for are collisions (i.e. elastic collisions), so they claim their detectors can see a signal if one of the nuclei gets bumped by a dark matter particle.
