Welcome to a special A to Z Challenge edition of Sciency Words!  Sciency Words is an ongoing series here on Planet Pailly about the definitions and etymologies of science or science-related terms.  In today’s post, K is for:

KARDASHEV SCALE

In 1963, Soviet scientist Nikolai Kardashev published this paper concerning the search for extraterrestrial intelligence. Kardashev seems to have been primarily interested in how much information aliens might be able to transmit to us across the vastness of space.  This, in turn, relates to how much energy an alien civilization is able to produce, because the more energy you have, the stronger your radio signals can be.

Kardashev summarized his thoughts on this by devising a scale—now known as the Kardashev scale.  In Kardashev’s original system, there were only three types of civilizations:

• Type I: a civilization that has harnessed energy on a planet-wide scale.  Kardashev considered Earth to be a Type I civilization.
• Type II: a civilization that has harnessed the energy of an entire star, perhaps by building a Dyson sphere or some other megastructure around their own sun.
• Type III: a civilization that has harnessed the energy of an entire galaxy.  Kardashev doesn’t offer any examples of this, but I might point to something like the Galactic Republic/Galactic Empire in Star Wars—they’re approaching Type III status.

Later scientists have expanded on the Kardashev scale.  Humanity has been demoted to a Type 0 civilization, because we don’t really use all the energy available to us on our planet.  Not yet, at least.

We can also talk about Type IV civilizations, which can harness the energy of the whole universe, and Type V civilizations, which can harness all the energy of the multiverse, or perhaps all the energy of alternative timelines, or something like that. Examples?  I don’t know, maybe the Timelords from Doctor Who or the Q-Continuum from Star Trek. Or maybe these people.

So which of these civilizations should we expect to find out there? What sort of transmissions do we expect to see?

The problem with Type IV and V civilizations is that their activities would be, to us mere mortals, virtually indistinguishable from nature.  As for Type 0 and Type I, their radio signals (if they’re sending any) may be too weak for us to detect over all the background radiation of the cosmos.

But the Type II and Type III civilizations… Kardashev was pretty optimistic about our chances of finding them.  In his 1963 paper, Kardashev argues that it’s absurd to think Earth is the only planet with intelligent life, and furthermore most alien civilizations should be far older and far more advanced than we presently are.  You may recall Enrico Fermi made a similar argument.

So there should be plenty of Type II civilizations out there, and perhaps a few Type IIIs as well, all chattering away in loud, easy-to-detect radio transmissions.  Or so Kardashev claims.  “In any case, the deciding word on this question is left to experimental verification,” he wrote.  But after fifty years of trying to detect something… anything… what has the experimental evidence shown us?

That’s a fair question.  And yet I have to agree with Kardashev: it is absurd to think Earth is the only planet with intelligent life.  So once again, in the immortal words of Enrico Fermi, where is everybody?

Next time on Sciency Words A to Z… wait, did we detect a signal?  Nope.  False alarm.