Some physicists are questioning the idea of space-timeSAKKMESTERKE/SCIENCE PHOTO LIBRARY Physicists of the 19th century assumed that space was distinct from time – and two researchers now suspect they were correct to do so. Their conclusion, which comes from considering the behaviour of qubits, questions the now-dominant idea that four-dimensional space-time is the fundamental fabric of physical reality. A qubit is an object that has two possible states – for example, two different spins. Because it is quantum, a qubit can also exist in combinations of those states that any familiar object could never take on – a phenomenon known…