"the flat universe remains the leading model of our cosmic surroundings"

Scientists think the universe is flat, but new observations suggest that we might actually be living in a gigantic sphere. Whoa.

In current quantum field theory, causality is typically defined by the vanishing of field commutators for spacelike separations. Two researchers at the University of Massachusetts and Universidade Federal Rural in Rio de Janeiro have recently carried out a study discussing and synthesizing some of the key aspects of causality in quantum field theory. Their paper, published in Physical Review Letters, is the result of their investigation of a theory of quantum gravity commonly referred to as "quadratic gravity."

One of the great counterintuitive puzzles of quantum mechanics is wave-particle duality. This is the phenomenon in which objects behave both like particles and like waves. Numerous experiments have shown that a single particle—an electron or a photon, for example—can interfere with itself, like a wave. The double slit experiment, in which a particle passes…