Lately, there have been a number of alternative methods of doing SETI coming out from researchers
seeking to broaden our ability to detect alien civilizations after decades of radio SETI
that has, so far, been fruitless.
One such method is to look for stars that simply blink out with no natural explanation.
But, as anyone familiar with the concept of a Dyson Sphere knows, technology can dim a
star or eventually block it completely and that should be detectable in two ways, one
is the act of construction progressively blocking the star's visible light until it blinks out,
and the other is through infrared emissions from the sphere once it's completed.
Both of these would have very distinct hallmarks as being technological rather than natural.
It's debatable as to whether engineering would allow for the construction of a full, very
large Dyson sphere, in fact the seemingly more plausible form of this kind of technology
would be a swarm of structures rather than one monolithic object.
But on the other hand, we really don’t know yet, and there may be ways of solving the
problems inherent to Dyson shells, especially if there is superintelligence involved.
One such type of superintelligence is a dyson sphere known as a matrioshka brain.
It is a computer that wishes to extract all possible energy from a star in order to make
the highest number of calculations possible.
For maximum efficiency, a series of nested spheres arranged like Russian Matrioshka dolls,
might be employed.
Engineering and managing such a megastructure is far beyond us, we can merely envision a
general view of it today, but it may possible for an advanced superintelligence to construct.
In the end though we simply don't know what a superintelligence could do.
But one thing we do know is that any such a monolithic dyson sphere technology would
at least make a star disappear in visible light and given that we've been doing star
surveys for over a hundred years now and have archives of data available, we can go back
into those archives and search for stars that have disappeared and then go from there to
try to determine why.
Just such a study was done by Beatriz Villarroel and colleagues at the University of Uppsala
in Sweden last year, link in the description below.
Using two different sky surveys, they looked at a sampling of hundreds of thousands of
stars for evidence that any of the stars had vanished.
In the end, they found one object that seems to have disappeared in the time between when
the two surveys were taken.
Unfortunately, this candidate turned out to be ambiguous, though it does seem to have
disappeared, at least for now.
The reason it was ambiguous was that certain things in the universe other than stars can
drop in brightness dramatically and seem to disappear, such as quasars.
The researchers couldn't pin down just what the object was, nor was it very consistent
with a star disappearing behind a Dyson shell when they looked for it in other surveys for
verification so the question remains open, but it’s highly unlikely that this was anything.
This is somewhat of a long shot method of doing SETI, the authors admit.
You really need a much larger sample spanning a much longer period of time to have any good
likelihood of catching the construction of a Dyson sphere, though there are tantalizing
cases such as KIC 8462852.
If that star blinks out at the end of the long-term dimming trend, then a serious look
at the Dyson sphere possibility will be warranted.
But individual stars might not be the only things to disappear due to the construction
of Dyson Spheres.
Entire galaxies might vanish if a classical Kardeshev Type III civilization were present
and had taken control of its entire galaxy.
These types of galaxies might only glow in the infrared and not emit much in the way
of visible light, if any at all.
Just such a search for this was conducted across the nearest 100,000 galaxies to the
Milky Way by Roger Griffith, Jason Wright and colleagues, link to the paper below.
Unfortunately no dead ringer candidate galaxies were found in the study, though they did find
a bunch of anomalous galaxies warranting further study for both astrophysical and SETI reasons.
The lack of good candidates so far for evidence of Dyson shells could mean that we haven’t
looked hard enough for them, or it might suggest that full on Dyson Spheres are not common
in the universe.
That can say many things, such as full Dyson spheres are not practical for anyone despite
having obvious uses.
Or, it might also suggest that intelligent, far-reaching civilizations are rare.
But, there is another possibility.
We really don't have many models to envision what advanced alien civilizations might look
like, we just have educated guesses based on our own behavior.
The Kardeshev scale, for example, is based on the assumption that an advanced alien civilization
would seek ever increasing amounts of energy as it expands.
But this may need a rethink.
It’s possible that such an advanced alien civilization may look technologically very
different from what we envision.
We assume that they would use massive amounts of energy in way similar to how we think we
will in the future.
But do we really know for sure that's what they would do?
Not really, and we ourselves currently have no plans for building a Dyson shell, though
our solar orbiting spacecraft might qualify as the beginnings of a Dyson swarm of sorts.
So if it turns out that dyson shells are rare or non-existent, it doesn’t really have
much bearing on the possibility of intelligent alien life in the universe.
It would just say that despite their obvious utility, Dyson shells are too hard to build.
Or, another possibility is that advanced civilizations use very little energy at all and instead
become extremely efficient with miniaturized technology, so instead of galaxy spanning
empires in the grain of Kardashev, maybe a single planet might provide everything an
advanced civilization needs.
Just food for thought.
Thanks for listening!
I am futurist and science fiction author John Michael Godier, perhaps currently sounding
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