What do you call a civilization that controls an entire galaxy? Sure, you can say “galactic empire”, but what separates a galactic empire controlling 50 stars, from one that has harnessed every single star in the galaxy? These distinctions don’t apply to the real world – yet – but they do shape how we think about the future.

According to Nikolai Kardeshev, a Soviet astronomer, the answer was energy. More than anything else, he believed, how much energy you control, how much potentential for work you had access to, determined where you were on the scale of civilization. I mean work here in the physics sense – work as in “doing stuff of any kind, changing things, affecting things”. Later scientists and futurists have debated whether he was right, but his scale for civilizations is still the one used the most today.

Dr. Kardeshev originally came up with a scale with three points: a type I civilization controlled the energy of an entire planet, a type II civilization controlled the energy of an entire star, and a type III civilization controlled the energy of an entire galaxy. In terms of numbers, he defined the energy of a planet as being about 10 to the 16th watts, the energy of a star as being about 10 to the 26th watts, and the energy a galaxy as being about 10 to the 36th watts. If you know a bit about exponents, you can see that this neatly makes each category one order of magnitude (or ten times) larger than the last.

In the years since the scale was invented, others have added onto the idea. Most widely accepted is the addition of three new categories on the same scale: a type 0 civilization, for something smaller than a type 1 (we are less than a type I civilization, still); a type IV, for a civilization that could control the whole universe, at 10 to the 46th watts; and a type V, for civilizations that can control *multiple* universes, presumably at 10 to the 56th watts. These definitions are more tentative, and it’s not clear if it’s even possible to reach a type IV civilization, let alone a type V.

So where do we rate, if we’re less than a type I? The esteemed astronomer Carl Sagan did the math for extrapolating up and down the scale, and rated us at about a 0.7. Michio Kaku, who is a very famous and well-respected futurist and physicist, thinks that humanity can real the level of a type I civilization in the next 100 to 200 years. That’s pretty exciting – we’re at a huge turning point in history!

So what does the Kardeshev scale mean for you? Practically, it’s only a hypothetical scale, but it’s still useful for how you think about advanced civilizations. Next time you watch Star Trek, you can note that they’re still a type I or type II civilization. It really puts in perspective just how far we have to go, that I can’t currently think of a single media franchise that even *tries* to portray a type III civilization! I hope this discussion has at least got you imagining just how much potential for growth there still is ahead of us.