This time, space-time itself can sometimes be two things at once. Until his dying days, the giant of 20th-century physics obsessed over the underpinnings of space and time, and how we can all share ...

In April, physicists detected a hint of a signal suggesting that dark energy, the mysterious energy of space itself, may be weakening ... one of the Nobel Prize–winning discoverers of dark energy, ...

The original version of this story appeared in Quanta Magazine. Ten years ago, the European Space Agency’s Rosetta probe pulled up alongside a dusty, icy lump the size of a mountain. The probe ...

The reference frames from which observers view quantum events can themselves have multiple possible locations at once—an ...