LifeWhy cat-like creatures vanished from North America for 6 million years Around 23 million years ago, North America's sabre-toothed cat-like animals disappeared, leaving the continent without felines for several million years. Now palaeontologists are solving the mystery of this "Cat Gap" Features
PhysicsWhat the thermodynamics of clocks tell us about the mysteries of time Surprising new insights about the strange physics underlying how clocks work could transform our understanding of time's arrow – and hint at how time works at the quantum scale Features