Have you heard about the Kardashev Scale? If not, you are certainly in for a treat.
For us mere mortals on Earth, the Industrial Revolution was a huge step up for humanity and caused massive socio-economic and geopolitical changes forever. But just imagine what would happen if we were able to develop our technology to such an extent that we could actually leave Earth?
How about colonizing our Solar System? Better yet, the entirety of the Milky Way?
Whilst normally the stuff of science fiction, it might just be a reality for humanity, someday. But are there any civilizations out there that have achieved these incredible feats?
In short, we have no idea, but there might be some candidates.
What is the Kardashev Scale?
The Kardashev Scale is a purely hypothetical scale for measuring a civilization's technological prowess based on the amount of energy it has available to it. It was devised in 1964 by a Soviet Astronomer, Nikolai Kardashev.
It first appeared in his paper, Transmission of Information by Extraterrestrial Civilizations.
Within the first version, Kardeshev originally defined three types, or categories, of civilizations on his scale. He gave a few examples ranging in scale from a planetary scale, to a larger stellar one and finally a galaxy-spanning empire.
Nikolai surmised that the overall status of a subject civilization is, generally, the product of two things: energy and technology. The better their technology, the more energy they can harness.
And not only that. The more energy a civilization has access to, the better their technology can later become. It was his belief that any society could just develop as far as its technology and ability to use energy would take it.
It is generally only concerned with energy consumption on a cosmic scale. Since the 1960s, the scale has had a few extensions proposed beyond the rather limited 3 originally defined by Kardashev.
These include new levels, 0, IV, and V, and the inclusion of other metrics beyond pure power availability.
"But," you might ask, "where do we humans currently fit on this scale?". Let's find out in the next section.
What are the 3 types of civilization?
As we've previously mentioned, Nikolai Kardashev, conceived of three tiers of civilization on his scale.
A Type I Civilisation
Type 1, as defined by Kardashev, is one still limited to one planet. But, critically, to have reached this level on the scale, the civilization must be able to harness all the energy available there.
For them, nuclear fusion is probably child's play as well as harnessing the antimatter. Other power sources from geothermal to other renewables would also be a given.
A Type II Civilisation
Type II civilizations are those that have managed to harness all the power of their local sun. An example strategy would be the ability to construct a Dyson Sphere around it.
These hypothetical devices would completely surround a star and be able to collect all of its energy. This would require quite the level of technological ability, to say the least.
They would also likely have colonized multiple planets in their local solar system. For them, extinction is a long-lost fantasy.
Little, if anything, would be able to kill them off, save themselves or a massive inter-species war.
A Type III Civilisation
A Type III Civilisation, or galactic civilization, would be able to control energy across many star systems and planets. The scale of their technological ability would be something beyond our current understanding and, possibly, imagination.
Some estimates have put this at about 10 Billion times the energy output of a Type II Civilisation. Who knows what else this kind of civilization would be able to achieve.
This would be something akin galaxy-spanning empires common in science fiction. From Star Trek, Star Wars, to the Imperium of Mankind in the Warhammer 40,000 Universe, they would be masters of the Universe.
But they would still need to obey the laws of physics. Travel between each corner of the civilization would not be possible unless they'd managed to circumvent the constraints of the speed of light.
Needless to say, this would be a people who have really made it - so to speak.
They would make regular use of Dyson Spheres and might even be able to tap the energy of black holes. A Type III might also be able to harvest energy from gamma-ray bursts and quasars.
Or some other, as yet unknown, energy source.
But wait, there are other tiers
There are other additions to the hierarchy, but these have been suggested after Kardashev's original list. They are as follows:-
A Type 0 Civilisation
A Type 0 Civilisation, as you can imagine, is one that has not yet been able to harness all the energy of its home planet. It is, therefore, a sub-global one that harnesses power from raw materials.
They do not yet have the ability to leave their home planet but are making steady progress towards it.
Some estimate, like theoretical physicist Michio Kaku, we might only be anywhere between 100 and 200 years away from graduating to a Type 1. That'll be nice.
A Type IV Civilisation
If a galaxy-spanning civilization isn't impressive enough, wait to you see a type IV. This would be one able to harness the energy across the entire universe.
Who knows what else they would be capable of?
A Type V Civilisation
Ok, how about one able to harness the energy from multiple universes? Absurd perhaps, but it might be possible in the far, far, future.
We simply cannot even begin to understand their technological prowess. Perhaps they have achieved immortality too.
One might be tempted to call them gods, for want of a better term.
If they exist, could we make contact?
Back in the 1960s, it was proposed by Freman Dyson, that it should be possible to detect the tell-tale signs of such civilizations from their IR emissions.
Back in 2015, researchers from the Penn State University scoured the skies looking for potential candidates. They were able to shortlist around 93 galaxies, from a massive 100,000, that might, just, be home to some advanced civilizations.
These galaxies showed signed of unusually high IR-emissions. This is a very rare thing to observe, but, they note, can be explained by thermal emission from warm dust.
Professor Garret, the author of the study, noted that:-
“The original research at Penn State has already told us that such systems are very rare but the new analysis suggests that this is probably an understatement and that advanced Kardashev Type III civilizations basically don’t exist in the local Universe,”
So that might just be the end of it. Type III Civilisations either do not exist or are yet to develop.
Or, as Professor Garrett explained “we’re missing an important part of the jigsaw puzzle here. Perhaps advanced civilizations are so energy efficient that they produce very low waste heat emission products – our current understanding of physics makes that a difficult thing to do.”
There has been another study suggesting that finding Yotta-eV (1024 electron Volt) neutrinos could be proof of at least a type 3 civilization. This would require using a quasar (a VERY energetic galaxy) as a particle accelerator.
For comparison, nuclear bomb reactions release a measly 106 eV per reaction.
Are we alone in the Universe? More than likely not, but are we likely to be visited, dare we say invaded, by a highly advanced civilization in the future?
The jury is still out. Let's hope that when they do arrive, they come in peace.