PhysicsHow materials that rewind light can test physics' most extreme ideas Strange solids called temporal metamaterials finally make it possible to investigate the controversial idea of quantum friction – and push special relativity to its limits Features
TechnologyWhat is artificial general intelligence, and is it a useful concept? The world's biggest AI companies have made artificial general intelligence, or AGI, their goal. But it isn't always clear what AGI means, and there is debate about whether it is a valuable idea Features