Fast radio bursts are flashes of radio waves lasting mere milliseconds, yet they pack as much energy as the Sun produces in a day. Their nature long remained a mystery. Now astrophysicists have a simple idea: these signals are nothing more than giant electrical sparks in the disks around black holes.

A searing-hot gas disk whirls around the black hole. Intense radiation acts like a gusty wind, blowing lightweight electrons outward while the heavier nuclei stay put. The disk becomes something like a thundercloud — except the electrical voltage builds up not for lightning, but for a radio burst.

When the voltage breaks down, the accumulated charge is released in an instant, and we detect a fast radio burst.

Scientists tested the model on a known burst and found an exact match with its spectral portrait — the way energy is distributed across frequencies. This allowed them to calculate densities and charges. A similar mechanism likely operates for neutron stars — the ultra-dense remnants of exploded stars.