“Astronomers using NASA’s Hubble Space Telescope got a first-hand view of how dark matter behaves during a titanic collision between two galaxy clusters. The wreck created a ripple of dark matter, which is somewhat similar to a ripple formed in a pond when a rock hits the water.
The ring’s discovery is among the strongest evidence yet that dark matter exists. Astronomers have long suspected the existence of the invisible substance as the source of additional gravity that holds together galaxy clusters. Such clusters would fly apart if they relied only on the gravity from their visible stars. Although astronomers don’t know what dark matter is made of, they hypothesize that it is a type of elementary particle that pervades the universe.”
This is way cooler than evarrything I’ve read the last couple of months. The whole dark matter topic is insanely exciting. Considering that 20% of the universe’s mass is supposed to be dark matter and that without that matter planets would just leave their orbits it’s no wonder that lot’s of people are so excited about it.
The whole idea of dark matter came up when an astronomer named Franz Zwicky observed a galaxy cluster and figured out that the mass of that cluster isn’t big enough to explain why the galaxies keep sticking together. The observed mass and the observed motion just didn’t fit together. He was also the one who came up with the idea of dark energy in the first place. However, his colleagues denounced him as being a crackpot – the idea just wasn’t sexy enough, it sounded to esoteric.
Later the idea became more popular when astronomers observed more weird behaviour. The stars in spiral-galaxies should rotate the slower, the farer away they’re from the core of it’s galaxy – however, they don’t, they’re moving faster than they are supposed too. So where’s the extra gravity coming from?
Dark matter, is the theory. Now they still have to figure out what the heck dark matter is after all. Wikipedia lists three different types of dark matter. It could simply be ordinary baryonic matter, like clouds of very cold dust – that’d be the most simple theory and doesn’t involve any weird matter at all. The other two idea what dark matter could be are Hot and Cold dark matter, but since I ain’t no physicist I’m not not to explain them, refer to Wikipedia.
Probably Tomaso could explain that even better than I could possibly do :)
Spiegel Online also has a nice video (in german, flashy stuff) with some cool animations and more detailed information.
Tomorrow I’ll be off for BBQ and beer. After that people can claim: “He’s so dense, light bends around him“.