Could Alien Spacecraft Propulsion Explain the Cosmic Mystery of Fast Radio Bursts?

It’s an “out there” hypothesis, but radiation from alien spacecraft zooming around space could account for the strange bursts of radio waves coming randomly from the deep cosmos.

M. Weiss/CfA

Powerful bursts of radio waves have been observed at random all over the sky and astronomers are having a hard time figuring out what the heck could be causing them. Many natural phenomena have been put forward as candidates — from massive stellar explosions to neutron star collisions — but none seem to fit the bill. It’s a mystery in its purest sense.

Pulling the alien card will likely raise some eyebrows in some academic circles, but if these so-called fast radio bursts (FRBs for short) end up lacking a satisfactory explanation, according to Avi Loeb of the Harvard-Smithsonian Center for Astrophysics (CfA), an artificial source (e.g. advanced extraterrestrial intelligence) could become the prime suspect.

“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 in a statement. “An artificial origin is worth contemplating and checking.”

FRBs are super weird. First detected in 2007, several radio observatories on Earth — including the famous Arecibo Observatory in Puerto Rico and the Parkes Observatory in Australia — have serendipitously detected only a couple of dozen events. And they are powerful; in a fraction of a second, they erupt with as much energy as our sun pumps out in 10,000 years. These are lucky detections as they only occur when the radio dishes just happen to be pointing at the right place at the right time. Astronomers predict there could be thousands of FRB events across the entire sky every single day. There seems to be no pattern, they appear to originate from distant galaxies billions of light-years away and they have no known progenitor.

So far, FRBs have been mainly identified from looking back through historic radio data, but now, the Parkes Observatory has a real-time FRB detection system that will alert astronomers of their detection, allowing rapid follow-up investigations of source regions. This system resulted in a breakthrough last year when astronomers were able to work out that one FRB originated in an old elliptical galaxy some six billion light-years away. This single event helped researchers narrow down FRB sources — as the galaxy is old and exhibits little star formation processes, some production mechanisms could be ruled out (or at least determined to be less likely).

“This is not what we expected,” said Simon Johnston, Head of Astrophysics at the Commonwealth Scientific and Industrial Research Organisation (CSIRO) which manages Parkes, at the time. “It might mean that the FRB resulted from, say, two neutron stars colliding rather than anything to do with recent star birth.”

But say if the source is a little more, well, alien; why would extraterrestrial intelligence(s) be blasting this incredibly powerful radiation into space in the first place?

In their research to be published in Astrophysical Journal Letters, Loeb and co-investigator Manasvi Lingam of Harvard University looked at a form of beamed energy that could be used to propel interstellar probes to the stars. Vast planet-sized solar receivers could collect the required energy and the power collected could be transferred into a laser-like device that is bigger than we can currently imagine. Although the technology required to create such a device is in the realms of science-fiction, according to the researchers’ work, it’s not beyond the realms of physics.

This hypothetical mega-laser could then be used to blast a huge solarsail-like spacecraft across interstellar — perhaps even intergalactic — distances. The photon pressure exerted by this kind of propulsion technique could accelerate spacecraft of a million tons to relativistic speeds. The engineering details of such a device are only known to these advanced hypothetical aliens, however.

Like this… kinda. (Credit: Walt Disney Studios Motion Pictures)

This form of beamed energy would need to be continuously aimed at the departing spacecraft, like a dandelion seed being constantly blown through the air by a steady breeze, to help it accelerate sufficiently to its desired destination — so why would such a technology manifest itself on Earth as a mere radio flash in the sky? Well, to keep the beamed energy on target (i.e. centered on the spacecraft’s sail), it will remain fixed on the spacecraft. But the spacecraft, planet and star will all be moving relative to us, sweeping the beam across the sky, so the beam will only briefly appear in our skies and then disappear as a random FRB. Even if there’s a permanent “beamed energy station” continuously firing spacecraft into deep space, we may only ever see one flash from that location — space is a big place, we’d need to lie directly in the firing line (over millions to billions of light-years away) for us to even glimpse it.

And if these FRBs are originating all over the sky, from many different stars in many different galaxies, it could mean that this beamed propulsion technology is a natural progression for sufficiently advanced civilizations. We could be in the middle of a vast intergalactic transportation network that we can only join when we are sufficiently advanced ourselves to build our own beamed energy station — like an intergalactic bus stop. Mind-bending stuff, right?

Alternatively, FRBs could just be a natural phenomena that our current understanding of the universe cannot explain, but it’s good to investigate all avenues, scientifically.

“Science isn’t a matter of belief, it’s a matter of evidence. Deciding what’s likely ahead of time limits the possibilities. It’s worth putting ideas out there and letting the data be the judge,” concludes Loeb.

And you know what? I couldn’t agree more.

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