We may be living in a doughnut. It sounds like Homer Simpson’s fever dream, but that could be the shape of the entire universe – to be exact, a hyperdimensional doughnut that mathematicians call a 3-torus.This is just one of the many possibilities for the topology of the cosmos. “We’re trying to find the shape of space,” says Yashar Akrami of the Institute for Theoretical Physics in Madrid, a member of an international partnership called Compact (Collaboration for Observations, Models and Predic...