As we humans grow in numbers and technological sophistication, we will need to generate more and more energy for our use. That likely means ever more reliance on renewable sources of energy like solar and wind energy. Even so, there will come a point when we have tapped all available energy sources our planet has.
We do, however, live quite close to an
almost endless source of energy: our sun.
In 1960, physicist Freeman Dyson proposed
that an advanced civilization might dismantle all the other planets, asteroids,
and everything else in its solar system to create a sphere surrounding its star
to collect all the solar energy it emits to run the civilization. Because of
the 2nd Law of Thermodynamics, such a Dyson Sphere would necessarily
radiate excess heat in the form of a strong infrared glow. Dyson suggested that
we could detect excess IR radiation from any such civilizations in our galaxy.
If a civilization is in the process of building
a Dyson sphere around its star, we should detect periodic dimming of the star
as the completed parts orbit it. Those dips in brightness would look different
than a planet orbiting the star, of which we have discovered thousands. A
Jupiter-like planet would block less than one percent of the star’s light.
In 2015, astronomer Tabetha “Tabby” Boyajian discovered a star that displayed light dips of up to 22 percent. Astronomers dubbed it Tabby’s Star. Initially, they thought that this star had hundreds of comets in a cluster that crossed in front of the star. However, observations ruled that out. Many armchair scientists, and even a few astronomers, suggested it might be an incomplete Dyson sphere. With more observations, most astronomers accepted that the most likely cause of the light variations is a large dust cloud, probably from a moon that had shattered, and parts of the dust cloud periodically blocked some of the star’s light.
The hallmarks of a Dyson sphere can be
summed up easily: variability in a star’s brightness
and an excess of IR radiation of a particular pattern due to waste heat.
With Tabby’s star, the IR excess doesn’t exactly match a Dyson sphere. The
cloud of dust fits it better.
Recently, two separate
studies looked at the data from 3 satellite missions that have examined
millions of stars in the Milky Way looking for Dyson sphere candidates. One
group led by PhD student Matías Suazo at Uppsala University in Sweden describes
their study as “searching for extraterrestrial intelligence using indirect
signatures of astroengineering,” in other words Dyson spheres. They came across
more than a few compelling candidates. Fifty-three to be exact, stars that
possessed both accepted signatures of Dyson spheres.
Neither group has yet
convinced the astronomical community at large that they have indeed found Dyson
spheres, but most agree the studies are intriguing and need further study.
In 1964, a Soviet
astronomer Nikolai Kardashev proposed a method of measuring a civilization’s
level of technological sophistication. He determined a civilization’s level by
the energy sources it can utilize. According to the Kardashev Scale, a type I
civilization can utilize and control all the energy sources of its home planet.
That would include taming and using the energy of natural events such as
volcanoes, tornadoes, earthquakes, etc.
A Type II civilization
captures and uses all the available energy of its host star by creating a Dyson
sphere. A Type III civilization captures all the energy emitted by its galaxy,
every star, black hole, etc. Earth is currently considered to be a Type 0.7
civilization.
Have we finally found
Type II civilizations? Only further study can answer that question.
Each month, I write an astronomy-related column piece
for the Oklahoman newspaper. After
it is published there, I post that same column to my blog page.
This is reprinted with
permission from the Oklahoman and www.Oklahoman.com.
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