Chunk of Universe's Missing Matter Found

Received wisdom holds that dark matter and dark energy make up 95 percent of the universe, and ordinary matter, or baryons--the subatomic particles the forms planets, stars and the like--account for the remainder. The problem is, the luminous matter detected with the aid of optical telescopes has amounted to a mere 10 percent of the expected ordinary matter, and the baryons inferred by other means bring that total to only 50 percent.
New findings are helping to bridge this gap between prediction and observation. In a paper published today in the journal Nature, scientists report having identified the probable source of the rest of this missing matter. Data from the Chandra X-ray Observatory, it appears, indicate that the lost baryons may be swimming in diffuse rivers of gas in the intergalactic medium too hot to see with an optical telescope.