Often in science it takes a long time to understand exactly how confused you are. Nobody knew to wonder how the dinosaurs went extinct, for instance, until 19th-century fossil diggers realized that dinosaurs had existed in the first place. In the case of dark matter — the unseen something that seems to make up about five-sixths of the matter in the universe — the confusion has been building for a good 84 years, and shows no sign of going away.
That’s not how it was supposed to be. A few years ago, various instruments seemed hot on the trail of the unseen cosmic component. In space, the orbiting Fermi Gamma-ray Space Telescope detected possible hints of dark matter particles breaking down into visible components. In an Italian laboratory, an international team claimed provocative evidence of a seasonal “wind” of dark matter blowing through its specially designed detector, called DAMA. And 4,850 feet underground, in an abandoned South Dakota gold mine, the enormous Large Underground Xenon (LUX) dark matter detector geared up to collect the definitive data on the long-sought dark particles.
But instead of enlightenment, what followed was a new wave of confusion. The Fermi signal looked like a mix of known astrophysical processes and random galactic noise. The DAMA results did not match up with data from other detectors, and so aroused widespread skepticism. As for LUX, it was a huge success — just in a negative way. It delivered a high-quality null result, the scientists’ way of saying that they found exactly zero evidence for a great many of the hypothesized or allegedly detected dark matter particles.
