Theorist Avi Loeb of the Harvard-Smithsonian Center for Astrophysics and his Harvard colleague Manasvi Lingam have suggested in a newly-published paper appearing in Astrophysical Journal Letters that it could be possible for other civilizations to have created radio transmitters capable of being detected in other galaxies.

"Fast radio bursts are exceedingly bright given their short duration and origin at great distances, and we haven't identified a possible natural source with any confidence," said Loeb.

Further, they explore the possibility that Fast Radio Bursts could be the result of enormous solar-powered transmitters being used to power interstellar light sails. A sufficiently advanced civilization could potentially use such technology to visit other planets.

"We examine the possibility that Fast Radio Bursts (FRBs) originate from the activity of extragalactic civilizations. Our analysis shows that beams used for powering large light sails could yield parameters that are consistent with FRBs," wrote the scientists in their paper. "The characteristic diameter of the beam emitter is estimated through a combination of energetic and engineering constraints, and both approaches intriguingly yield a similar result which is on the scale of a large rocky planet. Moreover, the optimal frequency for powering the light sail is shown to be similar to the detected FRB frequencies. These `coincidences' lend some credence to the possibility that FRBs might be artificial in origin."

This idea challenges the more commonly held belief that FRBs are caused by natural--albeit extremely volatile and explosive--phenomena, such as supermassive black holes violently releasing cosmic material; blasts of superluminous supernovae; or a type of neutron star that batters everything around it with intense magnetic fields, known as a magnetar.