Physicists are increasingly entertaining a radical possibility: our familiar universe of three dimensions of space and one of time might be only part of a larger structure, with a hidden fifth ...

Yes, OK, four dimensions – time is a dimension too, albeit an oddly unidirectional one (see “Cosmic uncertainty: Does time go both ways?“). But we’ve long thought there might be more large-scale ...

Physicists have spent decades treating mass as something the universe simply hands to particles, a property encoded in equations rather than explained from first principles. A new proposal argues that ...