GENEVA — A $2 billion cosmic ray detector on the International Space Station has found the first significant hint of dark matter, the mysterious substance that is believed to hold the cosmos together but has never been directly observed, scientists say.

The first results from the Alpha Magnetic Spectrometer, which was sent into space two years ago, show evidence of a new physics phenomena that could be the strange and unknown matter, an international team at the European particle physics laboratory near Geneva announced Wednesday.