Space.com (February 25, 2010)
"Scientists are hot on the tail of one of nature's most elusive substances, the mysterious dark matter that is thought to make up the bulk of the universe. Many scientists think dark matter might even be hiding right under our noses here on Earth.
"Dark matter is especially tricky to find because of its dark nature. In fact, scientists don't know what it is. It doesn't emit or reflect any light, so the most powerful telescopes have no hope of spying it directly. It has been thought to exist since the 1970s based on observations of gravity's effects on large-scales, such as among and between galaxies – regular matter can't account for the amount of gravity at work.
"And dark matter doesn't often interact with most other matter, scientists theorize. One idea is that it flies right through the Earth, your house, and your body without bouncing off atoms...."
That last paragraph in the excerpt represents a huge improvement over quite a bit of media coverage of dark matter research. It took me a while - years back now - to learn that that "dark matter" wasn't simply material that wasn't illuminated - and wasn't hot enough to glow at observable wavelengths.
And yeah, dark matter really is exotic. So is dark energy.
If either exist.
Dark matter may be the 20th century's phlogiston. But as more and more data is crunched, it's looking like dark matter and dark energy exist.
That, or something that acts like them does.
I'm a little more-than-usually interested in this particular line of dark matter research: some of it's going on here in Minnesota, in the Soudan mine.
Putting a dark matter detector deep underground shields it from the sort of radiation and particles that are zipping around - and through - us all the time here on the surface. With 700 meters of shielding, there's a better chance of sorting out dark matter interactions with the detector from the background noise.
Dark matter isn't, apparently, just something that's 'out there.' It - or something that acts just like it - is in a cloud of stuff that's part of our Milky Way galaxy. Astronomers detected and mapped it, from its effect on the orbits of stars around our galaxy's center.
Looks like it's shaped sort of like like a rounded-off, and squashed, American football: It's a spheroid where the 'height,' 'length,' and 'width' are all different.
The odd thing is that, although it's clearly centered on the visible core of our galaxy - its longest axis is as right angles to the Milky Way's plane.
But that's another topic.
- "Dark Matter, Dark Energy, Galaxies, Mathematics and Observations"
(January 17, 2010)
- "Lemming Tracks: Dark Matter, Dark Stars, and Keeping Up"
(December 21, 2009)
- "Like, Far Out! Offbeat Galaxies"
(August 6, 2009)
- "Dark Matter, the Gruber Foundation's Cosmology Prize, and Cephid Variables"
(June 8, 2009)