Scientists are on the trail of a mysterious five-particle structure that could challenge one of the biggest theories in physics: string theory. This rare particle—never seen before and predicted not ...

For more than a century, physicists have suspected that the familiar three dimensions of space and one of time might be only ...

The problem with string theory, according to some physicists, is that it makes too many universes. It predicts not one but some 10 500 versions of spacetime, each with their own laws of physics. But ...