The KARDASHEV SCALE : when and how can Humanity Advance as a civilization?
Alien civilizations: the Kardashev Scale and the Dyson Sphere
Let's try to think about how far humanity has progressed in its 200,000 years of existence,
and especially in the last 150.
Well, our galaxy, approximately, is 10 billion years old.
If in about 200,000 years we have gone from being hominids hiding in caves to a society
that uses the internet, explores space, and builds robots, with a huge acceleration in
the last 150 years, where could an alien race born, say, 6 billion years ago have come?
That's a long time, during which time an alien civilization might have developed sophisticated
propulsion systems-perhaps faster-than-light, worm-hole technology, or some other kind of
cosmic shortcut that would allow them to colonize the galaxy and beyond.
Based on this consideration, one might ask: is there any way to classify the technological
level achieved by any civilization, including ours?
Well.
In an article of 1963, entitled "Transmission of Information by Extraterrestrial Civilizations"
the Russian astronomer Nikolai S. Kardashev proposed a system to classify any extraterrestrial
civilization, based on the energy available to them to be able to make radio transmissions
beyond the boundaries of their planet of origin.
This system took the name of Kardashev's scale.
Kardashev's motivation for coming up with the scale was that if we can understand how
advanced civilizations source their energy, we can look for clues that they are harvesting
or using it in our observations of stars and galaxies.
In fact, his scale provides a crude way of quantifying the detectability of a technological
civilization.
Type III civilizations would hypothetically have a huge impact on their host galaxies,
and be clearly identifiable due to their interactions with galactic objects such as stars and black
holes.
More speculatively, the transportation and communication mechanisms such a civilization
might use between these bodies could also be detectable.
Over the years, this scale abandoned the reference to radio transmissions, to refer, more generally,
to the degree of energy that a given civilization was able to use for any purpose.
The Russian astronomer devised this classification system because he noticed that the level of
energy consumption on Earth had been increasing steadily for centuries.
This scale originally included three stages, each with its own characteristic energy level
depending on the source of the energy used.
Let's try to find out how this works!
The first type - Kardashev I - is reached when a given civilization manages to exploit
all the energy potential present on its planet of origin.
If we take the Earth as an example, considering that almost all the energy available on our
planet is represented by the incident solar radiation, equal to 1.73×10^17 Watt per year,
while other energy sources such as geothermal (3.2×10^13 W) or tidal (3×10^12 W) are in
comparison negligible, it is clear why humanity is still very far from falling into this category
of civilization.
In fact, the world's energy consumption in the year 2019 was 1.75×10^13 W, which is
only one ten-thousandth of the total energy received from the Sun!
And as of now, there is no known way for human civilization to use the equivalent of the
total solar energy absorbed by the Earth without completely covering the surface with man-made
structures; which is not feasible with current technology.
However, a civilization with this capability, among many other things it could do, would
be able - for example - to completely control its planetary biosphere, modifying its climate
at will.
At the second level of the scale - Kardashev II type - are those civilizations that are
able to capture all the energy produced by the star of their solar system.
And for entirely we mean ALL the energy produced and radiated by the star, and not only the
energy that arrives on the planet where the civilization resides.
To make a comparison, the energy radiated from the sun is equal to almost 4×10^26 W:
an amount of energy a billion times higher than that which actually arrives on Earth.
Being able to harness this energy could ensure an alien civilization the ability to survive
virtually every known natural disaster.
Only the extinction of the star or the destruction of the entire solar system could bring such
a super civilization to its knees.
Once a type II civilization will have been able to harness all the power of its star,
very likely it may want to extend its horizons beyond the native solar system, pushing up
to more and more distant stars.
In this scenario we begin to find the first physical limits, since, as far as we know,
it is impossible to travel or communicate with speeds greater than (but also equal to)
those of light.
Traveling from one solar system to another, therefore, would be extremely difficult and
costly in terms of time and resources.
However, imagining that a highly evolved civilization has managed to find a way to overcome the
relativistic limits known to us, in a short time would be able to become a civilization
of type Kardashev III, able to colonize and then exploit the energy of its entire galaxy.
A super civilization of this level of technology, with the beauty of over 10^37W of energy,
would probably be able to survive every imaginable cataclysm: from close explosions of supernovae
to the too rapid expansion of the black hole at the center of their galaxy.
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The Kardashev scale, as originally conceived by its author, would end with the third type,
but this has not prevented astronomers and physicists - as well as science fiction authors
- to conceive even higher degrees, bringing to the extreme consequences the principle
of energy exploitation.
At a hypothetical degree Kardashev IV, for example, we would find a civilization able
to exploit the energy produced by entire clusters of galaxies, while at the degree Kardashev
V even all the matter and energy within its own observable universe and probably travel
beyond it ... But already a civilization of type III would be for us so advanced to escape
any attempt to predict how it could really be or what it would be able to do... and so
there is probably not much point in worrying about Type IV or V or VI...
And where do we earthlings stand?
Well, nothing prevents us to assume the existence of a civilization of "Type 0", that is the
one to which belong all civilizations able to use at least 10^6 W of energy.
The members of a type 0 civilization, as we can imagine, would be able to exploit only
a small part of the energy arriving on their home planet.
They would then be limited to exploiting the energy coming from raw materials.
They would not yet have the ability to leave their home planet but they would be trying.
Yes, you guessed it right: we are talking about us humans.
And, for the record, it seems that our current score, according to astronomer Carl Sagan
who has devised a logarithmic formula capable of calculating even the "decimal" or intermediate
levels of the scale, is 0.7.
In short, our current civilization would be a Kardashev 0.7!
Extrapolating on the basis of the current growth rate of our planetary energy consumption,
according to Michio Kaku, U.S. theoretical physicist, our species could reach the Kardashev
I level around the year 2200, Kardashev II around 5200 and Kardashev III around 7800.
Evaluations perhaps a little optimistic, at least as regards the timing for the achievement
of the last two levels...
What do you think?
Do you have any idea about it?
There is still another question hanging in the air: what would a society much more advanced
than ours have to do to be able to fully exploit the energy of their star?
And here comes into play the concept of Dyson's Sphere, proposed by the English physicist
and mathematician Freeman Dyson in an article of 1960.
In practice, Dyson believed it possible that a civilization sufficiently evolved, and therefore
in need of a growing supply of energy, could use the planetary material available to build
around the star a kind of shell capable of capturing all its radiation
Although such megastructures are theoretically possible, the construction of a stable Dyson
Sphere is currently beyond our engineering capabilities.
In fictional accounts, the concept of a Dyson Sphere is often interpreted as an artificial
hollow sphere of matter around a star, but in reality, Dyson realized that a solid shell
or ring built around the star would be gravitationally unstable (kind of like Saturn's rings, which
if they were solid would eventually become off-center and crash into the planet).
The structure that Dyson imagined consisted instead of a swarm of objects that travel
on independent orbits around the star, just as the individual blocks of ice and rock orbit
independently around Saturn.Not a Dyson sphere, then, but a "Dyson Swarm".
The purpose with which Dyson theorized the existence of such structures is the same as
Nikolai S. Kardashev: to simplify the search for alien civilizations, trying to hypothesize
how they might appear to an external observer and the signals they could send.
But how to find out if they really exist?
What signs would a Sphere of Dyson, located several light years away from us leak to the
outside world?
Its distinctive mark - wrote Dyson - would be the infrared radiation, in particular the
one at 10 micrometers: the light captured by the sphere would in fact heat the internal
surface is, and the heat would be observable outside as an excess of emission in the infrared.
The target of an eventual search would therefore be stars with a surplus of infrared, and with
significant variations in brightness due to the non-compact structure of the Dyson Swarm,
or to its still partial construction.
And to tell the truth, stars with strange brightness variations are certainly not lacking
... in recent years.
In particular, in 2015, you'll all remember how the web literally went crazy with the
news that the Kepler Space Telescope, had detected an anomaly in the emission of the
star KIC 8462852, a spectral class F object 1484 light years away in the constellation
Swan.
Also called Tabby's star, named after Tabetha Boyajian, the U.S. astronomer who carried
out the first studies of the star in 2011, KIC 8462852 is subject to periodic and intense
changes in brightness to which you can not explain, even assuming the existence of a
planet in transit.
Usually, in fact, when a planet passes in front of its star, the reduction in brightness
does not exceed 1%, and this only in the presence of very large planets, the size of Jupiter,
for example.
The hypothesis advanced to explain the phenomenon have been, in time, numerous.
It has been talked about fragments of comets, a planet that is about to be swallowed by
the star, a planet with rings similar to Saturn, a planet that has disintegrated or asteroid
swarms.
More recently some researchers have hypothesized the existence of a dust cloud of irregular
shape that rotates around the star, and this at the moment is perhaps the best explanation
we have.
Among the first hypothesis advanced was that made a lot of discussions and immediately
captured the imagination of many: the existence of a mega alien structure that partially surrounds
the star.
Around that distant star there would be an incredible artifact made by a civilization
of level Kardashev II... a kind of Dyson's sphere, to harness all the energy of the star
and use it for their purposes, whatever they are.
Hypothesis that the same theoretical physicist Michio Kaku seems to be inclined to share..,
Tabby seems to have a mass of about 1.43 times that of our Sun and a diameter of slightly
more.
The alien structure should therefore contain an object of that size.
According to David Kipping, of Columbia University, the structure should still be at a certain
distance from the star, both not to be destroyed and to... justify just those variations of
brightness detected by our instruments.
So, on balance, it turns out that the diameter of the Dyson sphere should be at least 5 times
that of the star.
In addition, since the variation of brightness is large and irregular, we must imagine that
this mega structure is made by a swarm of small bodies arranged to form the sphere,
or at least by a number of large bodies: just like the Swarm of Dyson we talked about a
little while ago ... a sort of huge spherical puzzle made of thousands of probes with dimensions
similar to those of a small asteroid.
But if the Dyson sphere really existed, what should we expect to see that confirms its
existence?
As we said earlier, we should observe a very noticeable infrared radiation.
Well, this excess of infrared radiation, at the moment has not yet been identified.
Moral, for now we have to be satisfied to give to the phenomenon a "natural" explanation,
and postpone to other occasions the possibility to meet the Kardashev civilizations, with
all the frightening that their superhuman indifference could instill in the soul of
us earthlings, still much closer to the caves than to the stars.