Stephen Hawking has shocked physicists by admitting “there are no black holes”. In a paper published online, Professor Hawking instead argues there are “grey holes”. “The absence of event horizons means that there are no black holes—in the sense of regimes from which light can't escape to infinity,” he says in the paper, called Information Preservation and Weather Forecasting For Black Holes.He says that the idea of an event horizon, from which light cannot escape, is flawed. He suggests that instead light rays attempting to rush away from the black hole’s core will be held as though stuck on a...