A persistent claim to have detected dark matter looks wrong

NEGATIVE RESULTSDAMADAMADAMA are rarely reported widely. But they can be important. And this week sees one such—the possible demolition of what had been thought to be a sign of dark matter.Twenty years ago results from , a particle detector housed under a central-Italian mountain, suggested that this mysterious stuff, thought to make up 85% of all matter in the universe, had been detected. ’s operators saw an oscillating signal, peaking in June and at its lowest ebb in December, which was consistent with the Milky Way being embedded in a halo of dark matter. Because Earth’s axis of rotation is tilted with respect to the disc of the Milky Way, the flow of dark matter through the planet should vary seasonally as it orbits the sun. Calculations suggest the dark-matter flux should reach a maximum in early summer and a minimum in winter, which is what found.