One big problem for the alien idea is the variety of locations and distances involved. Of the FRBs that have been localised, some are from billions of light-years away; others are from hundreds of millions.
As astronomer Seth Shostak of the SETI Institute has noted, that alone is reason enough to discount the hypothesis that FRBs are extraterrestrial communications.
“How could aliens organise so much of the Universe to engage in broadcasting the same sort of signal?” he wrote in a blog post last year.
“There’s hardly been enough time since the Big Bang to coordinate such widespread teamwork, even if you can think of a reason for it!”