Nearly a century ago, scientists proposed that a mysterious invisible substance they named dark matter clumped around galaxies and formed a cosmic web across the universe.What dark matter is made from, and whether it is even real, are still open questions, but according to a study, the first direct evidence of the substance may finally have been glimpsed.More work is needed to rule out less exotic explanations, but if true, the discovery would go down as a turning point in the decades-long searc...