SpaceBlack hole firewall: Trouble on the edge The problem that Stephen Hawking spotted around black holes has made a fiery return. Anil Ananthaswamy reports on how it threatens quantum theory and gravity Features
SpaceQuantum skyfall puts Einstein's gravity to the test Dividing and recombining atoms as they fall down a 110-metre-high tower could help create a quantum theory of gravity ¿ìè¶ÌÊÓÆµ