do alien space sailors unfurl their solar sails to surf interstellar laser beams?

A new proposal posits that some of the fast radio bursts we've been routinely detecting may be coming from aliens, though not on purpose...

Remember when fast radio bursts, or FRBs, were bizarre anomalies which may have been the birth cries of exotic black holes, then alien signals, then impatient scientists' snacks, then once again odd anomalies, which may be neutron star quakes? Well, they're now being tied to aliens once again, but this time as chance detections of their propulsion systems. Much like we've been planning to send tiny probes to out nearest stellar neighbor using the power of a really big laser, so too could an alien civilization use solar sails powered by massive lasers, powerful enough to theoretically accelerate the weight of a skyscraper to relativistic velocities.

As the planets used to build their immense laser canons and act as relays for traversing starships zip by us along with everything else in our dynamic universe, we get momentary blips of energy we record as extremely fast radio bursts, or FRBs. No one is claiming that this is indeed proof of advanced alien civilizations, but it's an intriguing look at what else could be the source of these strange signals we still can't quite explain, even if it is extremely speculative. Still, is it realistic when we look at the big picture and the data we've gathered so far?

Perhaps the first hangup we'll find is that FRBs travel an awfully long way to get to Earth, and one pulse that traveled over 6 billion light years even gave us a chance to learn a little more about the makeup of our universe. Lasers, even electron ones, disperse with distance and lose power. It's unlikely that we'd detect a strong pulse from halfway across the visible cosmos since we'd be dealing with a power output on the level of supernovae rather than just a big laser, though if an alien species can summon that much energy, it would be one of the most amazing discoveries ever.

Still, that kind of output almost has to involve antimatter and if you've mastered antimatter collisions, you're probably not going to need solar sails to traverse deep space. You could just build an antimatter catalyzed fusion engine and maybe even a warp drive if some fancy math we've done on the subject is correct. Now, if FRBs were in our own galaxy or close by there may be something quite compelling in this scenario, though exactly how we could confirm it seems tricky.

But at the same time, it's understandable why this story took off. Solar sails is a technology we actually understand and can build given enough money and political willpower, and have actually deployed a working prototype of this concept. The idea that sufficiently advanced aliens can also figure out a very attractive concept for deep space propulsion is a pop sci goldmine, as is the notion that we could detect them with our existing technology and may already have.

Keep in mind that this isn't the first idea of how we could find aliens by their use of relativistic propulsion either; scientists come up with a lot of unconventional and media friendly ideas for SETI to test on a regular basis. And while I don't want to earn myself a reputation as the Not Aliens Guy, it would be negligent on my part not to point out that while detecting relativistic or high energy effects is plausible, confirming that they're truly caused by alien spacecraft is extremely difficult.

There will always be all sorts of other perfectly natural phenomena that can explain what we saw in an indirect signal. Anything short of direct detection is up for debate. Still, even though this is highly speculative and more excitement than really enticing data, we need more hypotheses like this and coverage of them on a daily basis. After all, what if we manage to find evidence of advanced alien life, even if it's on a planet where it may have thrived hundreds of millions of years ago but has either long left, or is now clinging to survival while its aging sun is slowly sterilizing the now barren surface?

We did find a world that fits the bill to have went through exactly that while multicellular living things were just starting to evolve on Earth. Maybe this could finally unite a world that keeps taking itself to the brink of disaster by its myopic focus on the here and now, instead of its future and ultimate priorities.

Perhaps we really need aliens to be out there and be seen by our telescopes for the sake of our species' future and stories like this offer an optimistic respite from a seemingly never-ending parade of gloom and doom in the news? Maybe the notion of FRBs being side-effects of interstellar alien ships is wildly unlikely, but it's good that we're still trying and coming up with ideas for SETI…