After painstakingly observing two galaxies collide at 10 million miles per hour, scientists think they have proof that dark matter exists! Dark matter doesn’t emit or reflect enough light to actually be detected directly, but scientists have long believed that they can infer that it exists because of its effects on visible matter. For example, astro-stud Fritz Zwicky first theorized the existense of dark matter back in the 1930s. From Wikipedia:

Zwicky estimated the total amount of mass in a cluster of galaxies… based on the motions of the galaxies near the edge of the cluster. When he compared this mass estimate to one based on the number of galaxies and total brightness of the cluster, he found that there was about 400 times more mass than expected.

That weighty difference? The best they could come up with was calling it “dark matter.” Anyway, now, “We’ve closed this loophole about gravity, and we’ve come closer than ever to seeing this invisible matter,” says University of Arizona scientist Doug Clowe.

Check out the NASA’s press release if you want to be a real nerd.

via boingboing