Space.com (June 13, 2010)
Dark Matter Either Exists, or It Doesn't
"Dark matter and dark energy are two of the most mind-boggling ingredients in the universe. Ever since these concepts were first proposed, some astronomers have worked feverishly to figure out what each thing is, while other astronomers have tried to prove they don't exist, in hopes of restoring the universe to the more understandable place many would like it to be.
"A new look at the data from one of the telescopes used to establish the existence of this strange stuff is causing some scientists to question whether they really exist at all. Yet other experts are holding firm to the idea that, whether we like it or not, the 'dark side' of the universe is here to stay.
"Dark matter is a proposed form of matter that could make up 22 percent of the universe's mass-energy budget, vastly outweighing all the normal matter, like stars and galaxies. Astronomers can't observe dark matter directly, but they think it's there because of the gravitational pull it seems to exert on everything else. Without dark matter, the thinking goes, galaxies would fly apart...."
Literary allusions to the Star Wars movies aside, this is a pretty good article.
There's a short overview of what dark matter and dark energy are - why some cosmologists and physicists think they exist - and why some now don't. The reason, as I see it, that there isn't a consensus is that we've got a fairly large set of data about the universe. Some of it is very precise, some isn't so precise: not wrong, just 'fuzzy.' Like some aspects of the microwave background radiation.
Slice and dice the data one way, you get support for the idea that dark matter exists. Run it through a virtual Cuisinart another way: and dark matter isn't so obvious.
This sort of thing is nothing new. Around 340 years ago, phlogiston was a pretty good way to explain combustion. It was a hypothetical substance present in materials that can burn. As it turns out, phlogiston doesn't exist. But until we learned more about matter, it was a model that made sense.
Which is about where we're at with dark matter today.
- "Dark Flow: This Universe on the Move?"
(March 18, 2010)
- "Looking for Dark Matter, Deep Under Minnesota"
(February 26, 2010)
- "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)