Perhaps the greatest challenge facing a civilization is surviving its infancy.
We ourselves struggle with that as we try to grow past the age of nation states, warfare
and the need for weapons that can cause our own extinction.
But once past that infancy, for many civilizations, our own included, there lies a future problem
that will confront us in our old age.
That problem is the life-cycle of stars.
Our own sun will begin to present problems for our civilization in only a few hundred
thousand years.
The first of these will be the general and slow brightening of the sun, though if we're
sufficiently advanced this particular issue would be somewhat easily mitigated with star
shades and advanced technologies for harvesting and controlling the sun's energy.
Past that period, however, it gets more difficult as the sun will eventually swell into its
red giant stage.
That end may be avoidable, one area of futurism that isn't yet well explored is the possibility
of managing, manipulating and even refueling ancient stars.
Alternatively, there are also hypothetical possibilities regarding the repositioning
of planets as the red giant's habitability zone migrates outward.
But no matter what a civilization does to mitigate the effects of a star's life cycle,
eventually available materials becomes a problem and the further along in time, the more this
problem will assert.
So for very ancient civilizations nearing the end of the life-cycle of their star, or
indeed the end of the universe, solutions for the problem of power generation become
limited.
Conventionally, one might turn to very long lived stars, such as the M type red dwarfs.
There are no shortage of those and they will be among the last living stars in the universe.
But there is another possibility, one that lies in our own sun's future.
It's hard to envision us as a civilization sticking around in this star system when the
sun finally goes red giant and ultimately to a white dwarf stage.
We'd need to manage a truly enormous planetary nebula that would form after the sun sheds
its outer layers and the solar system's remaining planets reorganize themselves as the sun loses
mass.
But once that stable white dwarf does form, or we colonize any of the other myriad white
dwarfs that will be around towards the end, then there is a way to support a civilization
using the energy of that stellar remnant.
It's a special type of Dyson sphere laid out in a 2015 paper by Ibrahim Semiz and Salim
Ogur, link in the description below.
This concept is noteworthy because it not only offers a way to build a Dyson Sphere
around a white dwarf, but it also avoids some of the pitfalls usually associated with building
a full on Dyson Shell.
More, this type of white dwarf Dyson sphere, if any exist right now, would be very difficult
to detect at a distance and might potentially explain why we haven't seen any Dyson spheres
in the universe so far.
It could turn out that the only practical type are those built around white dwarfs and
are simply too small to detect.
White dwarfs are tiny, our own sun when it reaches that stage will be roughly about the
size of earth, though far more dense.
This means that the habitability zone of the white dwarf is much closer to the star, so
you don't need an enormous sphere to encompass one.
It only needs to be just big enough.
Smaller spheres are easier to build and manage.
In the paper, the researchers calculate that you'd only need a thickness of about a meter
for the sphere, dramatically reducing the amount of material needed to construct it
as opposed to a classic Dyson sphere built around a main sequence star.
Less than the material contained in our moon in fact.
A smaller sphere also makes earth-like gravity possible, which is a problem for larger spheres.
The one drawback, however, is that less energy is available.
A white dwarf emits far less energy than a main sequence star like the sun.
While it should be enough energy to sustain an advanced civilization if they were frugal,
it would be low enough energy not to emit much infrared, the gold standard for detecting
Dyson spheres.
Given that we're dealing with a universe that's currently bursting with stellar energy, these
types of tiny spheres may not yet be common.
It would seem to make more sense to colonize high energy stars, at least for civilizations
that behave like us.
Though if a civilization doesn't need much energy, which is a possibility, they may choose
to go this route.
But in the far future when energy resources become scarce, these kinds of Dyson Spheres
might become common as outposts of life in a dying universe.
We may even have our own.
Thanks for listening!
I am futurist and science fiction author John Michael Godier and be sure to check out my
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explorations into the interesting, weird and unknown aspects of this amazing universe in
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