When facing a new and unknown astronomical phenomenon astronomers have two options: Put the word "dark" in front of it or state that it could be aliens. Fast radio bursts (FRBs) – incredibly powerful and brief sources of radio waves of unknown extragalactic origin – have attracted more and more of the latter.
The latest in this list comes from Harvard physicists Avi Loeb and Manasvi Lingam, who have produced a new study, accepted for publication in the Astrophysical Journal Letters, on what a potential artificial source of FRBs would look like.
"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," Loeb said in a statement. "An artificial origin is worth contemplating and checking."
Only 17 FBRs have ever been detected so far and their origin has astronomers scratching their heads. Out of the bunch, just one of them was seen repeating and is believed to have been formed by either a highly magnetized star or a supermassive black hole.
So, if we are contemplating an artificial origin, what would the source of such a powerful phenomenon be? The two physicists suggest that the FRBs could be beams that propel gigantic spaceships by blasting on their solar sails. What we see is the diffraction of the beam on the sail. They estimate that a sail could pull a payload of about 1 million tons.
"That's big enough to carry living passengers across interstellar or even intergalactic distances," said Lingam.
Things move from science-in-progress to sci-fi pretty quickly. The transmitter to send such a beam would require, if solar powered, a collecting area twice the size of Earth. And let’s not forget that pesky Second Law of Thermodynamics: No technology can be 100 percent efficient and it will emit heat, so the gigantic FRB transmitter would also require a humongous water cooling system twice the size of Earth.
Do the researchers actually believe that FRBs are produced by aliens, though? Not necessarily. "Science isn't a matter of belief, it's a matter of evidence," said Loeb. "Deciding what’s likely ahead of time limits the possibilities. It's worth putting ideas out there and letting the data be the judge.”
While open-mindedness is important, another hallmark of the scientific process is skepticism. The paper stresses how all of this is very speculative and still provides us with plenty of less far-out science too. The physicists estimated that based on the statistical expectation of 10,000 FRBs per day potentially visible in the sky, there should be one every 300 years happening in the Milky Way.
Hopefully, this will push for more investment in FRB research, even if it's just to prove these guys wrong.