"When you don't know what something is, you have to consider everything," Johns Hopkins physicist Simeon Bird told Nature magazine recently. He was talking about dark matter, the invisible stuff physicists now believe makes up most of the mass of the universe. They haven't been able to detect the mysterious stuff directly, but they're convinced it's out there due to telltale clues in the way, for instance, galaxies behave.
Their challenge now is to figure out what exactly dark matter is. Bi...
Published on October 05, 2016 12:27