Fast radio bursts are mysterious cosmic signals that last a mere thousandth of a second but pack as much energy as the Sun produces in a month. For such a pulse to be seen on Earth, a crowd of charged particles must emit radio waves in sync, like an orchestra. But just as an orchestra needs a conductor, the particles need a constant energy supply. If the burst source is far from a neutron star, the particles quickly lose speed. Their [tag:radiation]radiation is almost entirely scattered by oncoming particles — the medium becomes as impermeable as a concrete wall (its opacity to radio waves would reach 490). As a result, the signal fades on its journey.

A much more realistic scenario is one where everything happens right next to a magnetar — a neutron star with a record-breaking magnetic field. There, gigantic electric fields act like a power socket, continuously charging the particles. This discovery links fast radio bursts to the well-known pulsars — cosmic lighthouses discovered by Jocelyn Bell Burnell back in 1967. This sifting of models tells astronomers where to look for sources: in the immediate vicinity of neutron stars. It seems Enrico Fermi was right: nature builds its most powerful accelerators in the tightest corners of the Universe.