The Kardashev Scale
As we persevere in our search for other intelligent life out there in the far reaches of space, we should also remember that, if they exist, we have no idea what they would look like, or how powerful they might be in comparison to us, or how they would respond to us contacting them. This idea of how much “power” an alien race could have is an engaging one, and luckily, there happens to be a sweet scale that can help us to measure it! It’s called the Kardashev Scale, and it was first proposed in 1963 by Russian cosmologist Nikolai S. Kardashev, who was actually influenced by a project Launched by Frank Drake (of the Drake equation) called Project Ozma. Project Ozma’s goal was an attempt to locate extraterrestrial intelligences (ETIs) by scanning the sky for radio emissons. Inspired by the project, Kardashev began to wonder if a large number of alien civilizations might be millions of years ahead of us, and if so, what their radio signatures might be like. This caused him in 1963 to write a paper called “Transmission of Information by Extraterrestrial Civilizations”, in which he proposed a simple numbering system, from 1 to 3, that could be used to classify hypothetical alien civilizations based on the amount of energy they had at their disposal, specifically the power available to them for radio transmissions. These days, the scale has been modified by all kinds of scientists, astrobiologists and cosmologists alike, to simply describe the amount of energy available to an ETI for any purpose, and is often used to speculate about the kinds of technologies that advanced civilizations may possess. Here are the Kardashev Types:
(Type 0.7
Us, as estimated by Carl Sagan, although we are getting close to Type 1.)
Type 1
A Type 1 civilization would be close to Earth in terms of technological level, with an energy consumption of a bout 4 x 10^12 Watts. This civilization has harnessed all the power available to it on its home planet (i.e. all the solar energy, thermal, hydro, wind, etc.), but has not yet begun to exploit all of the solar’s systems resources. Defined even more radically, Type 1 status would only “truly be achieved once the entire planet is physically reconfigured to maximize its energy producing potential.” For example, the entire mass of a planet could be remade into a form of a massive solar array to feed the civilization’s power-hungry machines.
Type 2
In order to advance to Type 2, a planet would need to make a jump in energy consumption that will be equal to the output of the Sun per second. In order to reach this level, an ETI would need to capture the entire energy output of its parent star, with the best way to achieve this being the building of a Dyson Sphere. The Dyson Sphere was hypothesized by Freeman Dyson in 1959; it’s a hypothetical megastructure that would envelope a star at a distance of 1 AU and cover an incredibly large area of 2.72 x 1017 km2 (about 600 million times the surface area of the Earth). The sun’s energy output of around 4 x 1026 Watts would then be available to utilize for work. With all this available energy, a Type 2 civilization would be able to power its supercomputers and send out interstellar colonization waves.
Dyson Swarm, a type of Dyson sphere (courtesy, The Atlantic)
Type 3
Going one order of magnitude further, a Type 3 civilization would possess an amount of energy on the scale of its own galaxy, somewhere between 10^36 and 10^37 Watts. The entire galaxy of a Type 3 civilization would be colonized, with every scrap of matter exploited for energy. Consequently, to outside civilizations, a Type 3 one would appear completely invisible, with only a small amount of heat leakage registering in the far infrared (10 microns in length). Essentially, it would look like a hole in a galaxy, or an inexplicably large swath of open space. When looking for Type 3 civilizations, we might even do better to look for Type 2 civilizations on the brink of becoming Type 3, because their colonization waves would look like a giant bubble spreading outward from the parent star.
Type 4?
Hypothetically, ETI(s) that have harnessed the power of a galactic supercluster
Type 5?
Although highly unlikely, a Type 5 civilization would have the power of the entire universe at its disposal.
Problems With the Scale
Of course, what would any good hypothetical scale be without its problems? First, there is the Fermi Paradox, which is “the apparent contradiction between high estimates of the probability of the existence of extraterrestrial civilization and humanity’s lack of contact with, or evidence for, such civilizations.” We have no empirical evidence for the existence of Type 2 or 3 civilizations in our galaxy or galactic neighborhood, we do not see vast swaths of neighboring galaxies “disappear” from the visible spectrum (as predicted by the Scale), and we haven’t found any Dyson spheres yet either. Additionally, the Scale assumes that advanced civilizations have an insatiable appetite for energy, but what if it never really wanted to expand beyond a Type 1 or 2 level? Or what if it wanted to honor some kind of “Prime Directive” (woot woot Star Trek shout-out), or didn’t want to become some kind of Galactic Empire (woot woot Star Wars shout-out)? All these things would preclude a civilization from maybe even going Type 3. But, in the end, all this is conjecture, since we haven’t found anything yet. I say, let’s just keep looking and hope anything we find doesn’t end up wanting to “kill all humans” (woot woot Futurama shout-out).
Also, here’s a video of theoretical physicist Michio Kaku explaining the Types and why we’re still at Type 0 (but straining for Type 1!).
