[ExI] Dyson Spheres Are Missing From our Galaxy

[BillK]

The Milky Way, all on its own, has approximately 400 billion stars,
each with its own unique history and chances for life to have arisen.
Despite how technologically advanced humans have become, SETI searches
have all come up empty, perhaps implying that technologically advanced
civilizations aren't communicating in ways we would have thought. But
an advanced-enough planet might have built a sphere around their Sun —
a Dyson sphere — to harness 100% of its energy. Incredibly, we now
have the technology to detect them. If, that is, they exist.

May 3, 2018 Ethan Siegel

<https://www.forbes.com/sites/startswithabang/2018/05/03/dyson-spheres-the-ultimate-alien-megastructures-are-missing-from-the-galaxy/#7f3ee82a3138>

Quotes:

The European Space Agency has just released a huge suite of data from
the most powerful satellite ever to map and survey the stars in the
Milky Way: Gaia. They've recorded information about a whopping 1.7
billion stars in our galaxy, allowing us to create the most
sophisticated 3D map of the stars in our galaxy ever.

With 1.7 billion objects surveyed in the latest data release, Gaia
could reveal Dyson spheres that are under construction. By correlating
with other infrared observatories, it could even potentially find
completed Dyson spheres that were radiating enough energy. At the time
of this publication, though, the full suite of data we have indicates
exactly zero Dyson spheres in the Milky Way.

But this doesn't necessarily mean there aren't any; it simply means
that if they're out there, we haven't seen them yet. Dyson spheres
could exist at greater distances, around smaller, lower-energy stars,
or with larger diameters than Gaia is capable of detecting. Infrared
observatories like WISE have placed major constraints on them, as
well, and next-generation observatories that could potentially detect
the waste-heat signature from such an object, like ESA's Euclid or
NASA's WFIRST, will have the capability to search for these Dyson
spheres out even farther.

There may yet be intelligent aliens out there, building vast
trans-planetary empires to collect and utilize as much energy as
possible, but the evidence for them is nil thus far. Until such
extraordinary evidence arrives, there's only one reasonable
conclusion: our galaxy, as best as we can tell, appears to be devoid
of these wished-for alien megastructures.
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So it seems that advanced civilizations don't build Dyson Spheres.
Either they die out before reaching that stage or they choose a
different path than building giant technology systems. Humans can only
speculate about what that different path might be.

BillK