To say anything about alien civilizations in the universe one must make certain assumptions,
such as they would do certain things as a matter of logic and that logic might be universal
to all civilizations, such as the use of energy, which is the basis for the Dyson swarm idea,
but also the use of large amounts of raw materials, at least at some point in their developmental
history to build things like habitats, or interplanetary ships or dyson swarms.
Obviously, our own civilization uses resources on a smaller scale.
We mine materials here on earth and turn them into computers, cars and gravel roads.
It seems clear that at some point, we will move out into the solar system and when we
do, we will almost certainly mine asteroids, indeed, murmurs of doing this are already
on the table in the arena of space exploration.
Eventually, we may advance so much that we mine other star systems routinely as we colonize
the universe.
In any case, if we want to build extensive structures in space, it will eventually become
necessary to set up the infrastructure to gather local materials as opposed to launching
it up from Earth, and could be seen as a matter of killing two birds with one stone in that
the less asteroids there are in this system that could hit earth, the better.
But also, eventually this planet is just going to run out of some resources, at least those
easily accessible as opposed to mining asteroids.
That means that this also goes both ways as far as mining useful materials.
The asteroids contain materials that are not so common down here on this planet, but have
significant industrial use and general value, such as platinum or gold.
At some point, if we want to continue using scarce materials like that in manufacturing,
we'll need to go to space and get more or deal with increasingly expensive prices until
asteroid mining becomes so lucrative that someone will have no choice but to do it.
For alien civilizations, no matter if they are post-biological machine civilizations
or biological ones, they're probably going to do the same sorts of things, at least during
part of their development, probably a good long part.
And that may make them, or for that matter us, detectable at a distance.
Can we detect alien mining?
And, even if they've stopped mining long ago, would certain signatures of past mining operations
having once been active in a star system last for a very long time increasing our chances
of detecting it?
It depends.
One example of this to consider would be if you found a natural debris disc, but saw that
it was anomalously depleted of materials that should by all rights be there.
This hasn't happened yet, but a 2011 paper by Duncan Forgan and Martin Elvis details
just what you might look for in this regard if you came across something anomalous while
studying natural stellar debris disks, something that is no doubt likely to happen since they're
actively being studied on their own for scientific purposes.
And, as the instrumentation gets better, the likelier it will be that we will come across
more anomalous, weird star systems like Boyajian's star.
The authors note that not everything is likely to be useful for an alien civilization as
far as materials go.
You can see this with our own mining, not all kinds of rock that you find in a mine
are desirable, only those veins of ores that contain something of value are.
This means that alien mining operations might produce mining byproducts, or tailings if
you will.
Tailings in space means dust.
With mining asteroids, you're probably going to go after the low hanging fruit first, the
largest ones -- though this is not a hard and fast rule, small rich asteroids can be
good targets too.
But in general, with larger bodies you'll get more materials, and there are technical
advantages to mining an asteroid with some degree of higher gravity, but you'll also
produce more tailings, or dust.
The net effect of this could be that an active mining operation in a star system will reduce
the amount of large asteroids and increase the amount of dust.
Small dust grains tend to get blown out of star systems quickly, so if you see dust that's
being actively replenished along with no apparent effects due to large objects, which can be
indirectly inferred from infrared observations, then you may have a candidate for an active
mining operation.
Or not.
That can still be due to natural causes, such as dust collision cascades.
So how do you know for sure?
The authors advance three ways you might detect an alien civilization using the notion of
large scale alien mining.
The first is chemical.
Forgan notes that with high resolution spectroscopy you can study the materials present in a debris
disk, at least to some degree.
In general, this could tell you if any material that you would expect to see is missing in
the system's disk.
That doesn't say much, but if you're missing a host of valuable materials in a weird way,
it collectively might.
The second is the missing large asteroids.
If you see no evidence of them, that might be telling, though again, on its surface,
it might not mean much either.
But coupled with other factors, it might add to the equation.
And the third is the most compelling; infrared emissions irregularities.
When you muck out a mine on earth, you tend to put the worthless material in one convenient
place, you dump the tailings outside the mouth of the mine and let them roll down the hill
or you truck them off somewhere else.
This works in a related manner in a solar system, dust is bad, especially if you have
a lot of it so you have to put it somewhere out of the way.
In that context, it's just space debris that can wreak havoc on your equipment.
So you'd want to try to actively manipulate the material into, say, a ring.
You might do this by guiding small asteroids into orbit to shepherd the material, perhaps
like what happens with Saturn's rings.
Or you might do it artificially somehow, perhaps magnetically.
But regardless, you don't want the material in your workplace and since nature tends to
do things one way, and civilizations another, the end result might be a very unnatural arrangement
of material glowing in infrared showing thermal anomalies due to recent movement that might
otherwise be inexplicable in a normal, natural star system and provide a final answer as
to whether you're seeing an active mining operation.
But that's active mining, at least from our perspective light years away.
Detecting past, abandoned mining is much harder at a distance, but not impossible.
The longer in time you go the less evident it will be.
But in a weird way, at the same time, in one case it might be much easier.
Perhaps at some point we may find an asteroid in our solar system that is anomalous, and
appears to show evidence of having once been mined by a passing probe long ago, perhaps
even before we were even here.
Our solar system has been here for billions of years, and the galaxy even longer, so this
is not impossible.
But I suppose the biggest question of what would come of such a discovery is where did
they go?
Thanks for listening!
I am futurist and science fiction author John Michael Godier currently announcing the debut
of my newest book Supermind!
It's available in both e-book and paperback formats on Amazon, links below along with
a link also to a reading I did on my second channel, and will be available as an audiobook
in the coming months and be sure to check out my other books and subscribe to my channel
for regular, in-depth explorations into the interesting, weird and unknown aspects of
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