1399851
story
chill writes
"CNN is reporting that "Scientists have discovered evidence that hordes of dark, miniature galaxies surround ordinary galaxies, lending credence to the theory that the universe is comprised mostly of cold, dark matter." The study was partly funded by NASA and the U.S. DOE."
More and more... (Score:3, Interesting)
Yes, the mass of certain neutrinos and other "nearly-massless" particles does figure in, just like we've been theorizing and hearing for a long time. However, we are continually finding more and more of this evidence that there are other sources of mass in dark matter.
It'll be interesting to see the theories on what these "dark matter galaxies" are. Is it some form of dark baryonic matter? Or something else? Quite exotic, either way...
Re:More and more... (Score:2, Insightful)
So it's just not a matter of finding more mass, the mass needs to be located where it is missing.
Dark Matter Overview (Score:4, Informative)
Re:Dark Matter Overview (Score:2)
Re:Color distortion? (Score:3, Insightful)
Re:Color distortion? (Score:2)
- Piece of diffraction grating, the non-aluminized, see-through kind
- Box that toothpaste came in
- Tape and office supplies
Cut a round 1-cm hole in one end of the long, squarish box. Tape the diffraction grating over it.
Cut a narrow slit, with an X-Acto or similar knife, in the other end.
Now go look at something that lights up by heating gas. This would be either the sun or a fluorescent light, or a mercury-vapor light, etc. Look through the end with the diffraction grating. Compare the sun with a fluorescent--That's one of the ways they can tell what's in a star without going there.
Here's how to build a bigger one [nso.edu] with some links, but the toothpaste box one, you can carry around and impress your friends. (One way or the other.) Link from that page about a spectroscope made from an old CD [colostate.edu].
The galaxy is on Orion's belt? (Score:2, Funny)
Cold, Dark matter here on earth! (Score:4, Funny)
So that's what my wife is made of! I have to keep the furnace on 'broil' in the winter, and I've seen her step into the shade of a palm tree in the Caribbean and start shivering. Who should I send a skin sample to?
Details? (Score:1)
Now, gravitation (esp. gravitational lensing) is the only way to detect dark matter. The article shows that the gravitational lens is a "bright" galaxy. So how did they determine that these dark midget galaxies exist? They don't radiate light to be bent by the lens, and unless I'm terribly mistaken, the little circles around the larger one in the image [cnn.net] are in fact the same object, but distorted by the gravitational field of the central galaxy.
As for the second reason dark matter is supposed to exist (that the universe just isn't heavy enough): can't the stars/galaxies/clusters simply be more dense with ordinary matter than we thought? (This would require that the matter be colder than we thought in space, so that the total radiation corresponds with the experimental values).
In conclusion, for those who know about dark matter: why does it have to exist?