Knowing just where to point your radio telescope to search for alien signals is one of the
most vexing problems within the Search for Extraterrestrial Intelligence.
The reason for this is two fold, first, we have no idea where aliens might be.
Astronomers can guess based on a star’s habitability and look for planets around those
stars, and then point the radio telescope just to see, but that’s really about it.
The other problem is that an advanced alien civilization could exist almost anywhere if
they are space-faring.
Star systems that might not be suitable for native life to arise, might be fully suitable
for an advanced civilization to colonize.
This is compounded by the energy question within SETI, if you want to build a beacon
powerful enough for others to see, and have it run for long enough of a time, you need
to expend massive amounts of energy.
And that’s a problem.
Why spend so much on the off chance that someone will see your beacon?
It could well be that the reason we don’t see alien beacon signals everywhere is because
no one broadcasts like that as a matter of practicality.
That leads us to a question, are there situations where it would make sense for aliens to broadcast?
Could there be a way to determine just when and where to look?
The answer is yes.
Astronomical events themselves offer natural focal points for attention in the galaxy.
Assuming that advanced alien civilizations study astronomy, it’s reasonable to say
that any time anything happens in the galaxy it gets noticed.
One of the most visible events that can happen in a galaxy is a supernova.
Whenever one happens, there’s a good chance that every telescope in the galaxy turns towards
it, including our own.
This might make them a natural carrier or precursor for a communications signal.
Any civilization that detects or even predicts a supernova might turn a transmitter the opposite
direction of the supernova and blast off a contact signal knowing that as the supernova’s
light propagates out, any civilization doing astronomy further from the supernova will
be looking at it raising the chances that the alien signal will be detected in the process.
This is actually an old idea first proposed in the 1970’s by T.B.
Tang, link below, and ultimately means that recent supernova remnants might be natural
places to look for signals in addition to the rare occurrence of a natural real time
supernova.
But that’s not the only thing regarding supernovas and aliens that might be detectable
at a distance.
The fact is, supernovas are deadly if you’re close enough to them.
But to a civilization only a little more advanced than we currently are, they need not be resigned
to knowing their civilization was on borrowed time awaiting the explosion of a giant star
located just a little too close.
There is something they could do to protect themselves, and such a thing might just be
visible at a distance.
It’s a blast shield and unlike most conceptions of an alien megastructure, this one is fairly
easy to accomplish by moving around natural objects in your star system or Oort cloud
to block most of the damaging radiation from the supernova or gamma ray burst that would
otherwise destroy you.
In paper by M. Cirkovic and B. Vukotic, link below, they detail how to do this, and how
we might do it if we need to.
But such an alien blast shield would need to be actively maintained and might be detectable
by instruments like Kepler whenever it transits its star.
You might more readily see such things in star systems that are located close to stars
that are believed to be nearing a supernova or gamma ray burst.
I think this would be one of the more interesting ways to detect an alien civilization.
Imagine a scenario where our first detection of an alien civilization is to see their supernova
shield in a light curve.
Perhaps others saw this too, and much of the galaxy worries about the safety of the supernova
aliens.
Perhaps they might anticipate that and the first transmission we receive from an alien
civilization is a post-supernova message saying “we made it, here’s some data on what
a supernova is like up close.”
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently wishing everyone
a prosperous and happy 2018.
Instead of shooting off fireworks, it’s -18 celsius outside, I decided to write about
supernovas instead and be sure to check out my books at your favorite online book retailer
and subscribe to my channel for regular, in-depth explorations into the interesting, weird and
unknown aspects of this amazing universe in which we live.