Fast radio bursts from space are a uniquely 21st-century mystery. They were first identified just 10 years ago and, up until very recently, we've only caught about two dozen of them.
But a new telescope in Australia is already making it much easier to detect fast radio bursts, or FRBs, which makes this an appropriate time to delve into some key questions. For instance, what the heck is an FRB and where do they come from?
FRBs are essentially just what they sound like -- radio signals from somewhere in deep space that last for just milliseconds.
"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," Avi Loeb, a Harvard-Smithsonian Center for Astrophysics theorist, said in a press release in March.
An (extraterrestrial) intelligent explanation?
As with most space stuff that can't yet be explained without a doubt by some natural phenomenon, aliens have been proposed as a possibility, including by Loeb himself.
"An artificial origin is worth contemplating and checking," he says.
Loeb and his colleagues worked out how much power would be needed to send such signals across the universe. Turns out it would require covering two Earth-size planets with energy collectors, leading Loeb to theorize that such a massive project might be used not to communicate, but to propel starships using high-energy beams.
While aliens might be the most exciting possible explanation, that doesn't mean they're the most probable. There are, after all, natural phenomena in the cosmos that could generate such signals and are known to actually exist, which is more than we can say for extraterrestrials.
One aspect of FRBs that has made them so hard to trace back to a source is that they rarely seem to repeat. They're just detected and never heard from again. That is, until January when researchers announced they'd finally identified that FRB 121102 repeats.
This allowed them to trace the blinking signal to a surprising source: a distant dwarf galaxy 3 billion light-years beyond the Milky Way.
"That's weird isn't it? You'd expect to find FRBs where there are more stars ... more stars means more neutron stars," Shriharsh Tendulkar of McGill University and the discovery team said in January.
It's also weird because a signal that distant would have originated so long ago that Earth would have still been a largely lifeless rock at the time. This lends credence to the idea that FRBs might be like the aftershocks of cosmic cataclysms from when the universe was much younger.
Or maybe there are different types of FRBs out there or different explanations we haven't even thought of yet.
At least one case of an FRB was later explained by someone at an observatory opening a microwave oven door while it was running.
Clearly, it's still early days for the study of fast radio bursts, but the new Australian Square Kilometre Array Pathfinder and other upcoming next-generation observatories could help solve the mystery or at least provide some more solid clues.
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