If you’ve heard of the Kardashev Scale before, it’s probably because you’re  a fan of Science Fiction.

If you haven’t heard of it, it's a way of classifying civilizations… especially those of an extraterrestrial nature… based on how much energy they consume. So it might sound like it came straight  out of a Hollywood blockbuster, but the Kardashev Scale has some very serious scientific thought behind it.

It’s also more than just a guide in humanity’s continuing search for  extraterrestrial intelligence. This scale can help us predict the  next steps in our own advancement, and even anticipate some of their side effects. It can even prompt us to ask big  questions like “What do we value?” and “What do we want to work  towards long-term as a species?”.

So let’s take a journey through the scale that goes from a few blue whales at one end, to our potential intergalactic  overlords at the other. [♪INTRO] We’ve had radio telescopes focused on the sky for more than 65 years now. And while most scientists think we haven’t spotted any alien civilizations in all that time… or any alien individuals for that matter… it’s still important to know what to look for. That’s what Nikolai Kardashev  was thinking about in 1964, when he created the scale that  would eventually bear his name.

Or at least an anglicized version of his name. Kardashev figured that the more  energy a civilization consumes, the easier it would be to detect its radio signals from our neck of the woods. So he defined a Type I civilization… that’s a Roman numeral one… as using close to what  humanity was using at the time: around 40 quintillion ergs per second.

If you don’t know what an “erg”  is, I don’t blame you for that. So let’s convert that to something  more familiar: 4 terawatts. We were only using 4 terawatts  per second back then?

Oh my god, that’s adorable. Meanwhile, a Type II civilization  would harness all the energy of its own star, which would be one hundred  trillion times more than a Type I. And a Type III would harness all  the energy of its own galaxy, a hundred billion times more than Type II.

Sounds simple enough. And  perhaps a little too simple. Because in the decades since, countless scientists have iterated, edited, and  expanded upon Kardashev’s, I mean Kardashev’s original idea.

Probably the most famous of these was Carl Sagan. In 1973, he swapped the Roman numerals for Arabic, and created an equation that  would let you calculate decimal values if your alien civilization  fell somewhere in the middle. Which it seems like, might.

To craft that equation, he started by defining the energy that you’d plug in to get a final value of 1 - 10 Petawatts. Also known as 10 to the 16 watts. While that number is somewhat arbitrary, it started a pattern where  each step of the scale adds another 10 zeros to the number of total watts.

In other words, a Type 2 civilization consumes 10 to the power of 26 watts, which is roughly the output of the Sun. And Type 3 is 10 to the power of 36 watts, which isn’t too far off from the estimated energy output of the Milky Way galaxy. When Sagan devised this scale, if  you added up all the energy humans generated, we’d be sitting not at  a Type 1, but a whopping Type 0.7.

And if we can score a value less than one, that means we can find out what  a Type 0 civilization would be. If you extend the scale down  to 10 to the power of 6 watts, you reach the level of biological power. In fact, based on their  active metabolic rate alone, a pod of just three blue whales would  qualify as a Type 0 civilization.

Hahah, which I love. That’s great. Unfortunately, they’re such solitary creatures, that they normal don’t team  up for long periods of time.

Scientists have also extended the Kardashev Scale in the other direction,  introducing a Type 4 civilization, consuming 10 to the power of 46 watts. That’s about two orders of magnitude off the energy of the entire observable universe. Some have even discussed the  idea of a Type 5 civilization, which would have to harness the  power of multiple universes.

And if they can do it, I wish them well. But before we get too carried away,  we should take a moment to state the obvious: this classification  system is coming from the perspective of just one civilization, which  hasn’t even made it to Type 1 yet! As of 2020, humanity is sitting somewhere around 0.7276 on the Kardashev scale.

But it’s hard to calculate all the  energy consumed by our civilization, so that’s just one estimate  floating around the literature. The study that calculated that number also forecasts we’ll reach 0.7449 by 2060. Meanwhile, other papers attempt  to predict when we’ll finally hit Type 1, providing guesses  between 2333 and 2404.

All of these guesses depend a lot  on what the future holds for us. For example, if we figure  out how to generate power through nuclear fusion, we could bump ourselves up to 0.7719 by the end of the 21st century. Now, boiling everything down to  a single score like this makes it easy to get caught up in  reaching the next milestone.

But our long term advancement  on the scale also depends on our ability to deal with the side effects  of generating more and more power. Right now, we’re in the middle of a climate crisis because of our insatiable hunger for energy. Any new technology will come with  new side effects, and our success as a civilization will depend on our  ability to anticipate and solve them.

So we definitely shouldn’t do whatever it takes to make “Number Go Up!” as fast as possible. But we can still think about what we might need to do to make that happen. Most visions for reaching  Type 2 involve building a megastructure of sorts around  our Sun to capture its radiation.

The most famous of these  is probably a Dyson sphere, which, as the name implies, requires surrounding our star with one giant light-absorbing machine. Although it could technically involve a swarm of separate spacecraft  all working in tandem. This sphere doesn’t have to be solid, despite the many SciFi depictions as such… including our script editor’s personal favorite: the one that caused Captain Montgomery Scott to get stuck in a transporter  pattern buffer for 75 years.

I also enjoyed that one. But building such a device  is…easier said than done. To acquire enough material,  you’d need off-world mining.

Be it the Moon, or asteroids, or even  the entirety of the planet Mercury. But even if we do manage to  build some kind of Dyson swarm, we’d still need to beam all  that power back to Earth. Or wherever we’re living at the time.

Lucky for us, engineers are  already kinda working on this. In 2023, a team from Caltech  completed the first power transfer from a satellite  down to the Earth’s surface, transmitting it in the form of microwaves. So it might take thousands of  years for humanity to reach Type 2.

And Type 3 is likely hundreds of  thousands of years beyond that. To harness the power of the  galaxy, you’d need tons of Dyson spheres around tons of stars,  or a similar structure around the supermassive black hole  at the center of the galaxy. A black hole emits energy in a bunch of ways, but the most likely source we’d  capture is heat from friction… created by all the debris swirling around the black hole in its massive accretion disk.

But before we get to what an advanced civilization could even do with all that energy– Why would they even want it?– We’re gonna do a quick ad. Thank you for watching SciShow! We think these videos and all  the great information in them should always be available for  anyone who wants to watch them.

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Right now you can go to complexlylearnathon.com to check out the schedule of events! Alright, so what do you do with all of the energy from a Type II civilization? From our lower-than-Type-1 perspective, pretty much, I mean, anything they want to.

Maybe they’d run some super advanced form of AI using a Matrioshka Brain… a hypothetical computer made up of nested Dyson spheres with a star in the centre. And if you’re thinking, did  he mean to say MatrOYshka? We had a long discussion about this.

Or maybe they want to build a Shkadov Thruster: A partial Dyson sphere that  harnesses solar radiation to steer a whole solar system/ through the galaxy. A civilization could use such a device… which is once again entirely hypothetical… to avoid dangers like a galactic  collision or a nearby supernova. Or maybe, this advanced civilization wants to probe the most fundamental bits of reality itself.

Some of modern physics’ greatest  mysteries exist at the Planck length, which is a hundred million trillion  times smaller than a proton. Our equations simply break down when we try to look at stuff that small. Theoretically, you could study this  scale with a particle accelerator, but it would have to be a lot bigger than  humanity’s Large Hadron Collider.

And by “a lot” I mean it would need  to be the size of an entire galaxy. Which a Type 3-point-something  civilization could totally do. If aliens ever did construct such a device, human scientists could detect  some of the super duper high energy particles it was  emitting into the greater cosmos, if they just so happened to  hit the Earth on their journey.

Not just humans that finally  managed to reach Type 1. Humans now. As of the recording of this video, though, we haven’t detected any Type 3 civilizations.

But that’s not because no one tried looking. Based on a lack of evidence, two  studies published back in 2014 and 2015 concluded that Type 3 civilizations must be rare in the local  universe, if not non-existent. And despite several weird light signatures found in the sky over the years, which some people proposed could  turn out to be megastructures, we don’t have any solid evidence of a Type 2 civilization out there, either.

And technically, because Kardashev’s  original scale got redefined, we don’t even have evidence  of a Type 1 civilization yet. Which sounds like a massive disappointment. But a lack of evidence isn’t entirely useless.

One thing it highlights is  the so-called Fermi paradox: If there’s a high probability other  intelligent life exists in the universe, why can’t we find them? Maybe there’s some sort of great filter  that civilizations rarely get past. Because as a civilization  gets access to more energy, it also gains the ability to destroy itself.

Humanity gained this ability when it hit around 0.6 on the Kardashev Scale. So maybe the further a  civilization advances on the scale, the more likely they’ll destroy themselves. Maybe advanced civilizations need to learn to rein in their expansionist  instincts to survive.

Maybe that includes our advanced civilization. But energy usage is just one way to  measure a civilization’s progress, and it doesn’t capture everything. Over the decades, scientists have  proposed a number of alternatives to the Kardashev scale to  capture other forms of progress.

Like, perhaps some alien cultures out there have opted to live in harmony with their environment, rather than strive for  ever-increasing consumption. A 2020 study proposed that  we focus on the relationship between the civilization and  the environment around it. This scale, which uses  “classes” instead of “types”, starts with a civilization  using the environment as-is, as we observe animals doing, for example.

That’s Class 0. Then at Class 1, a civilization  progresses to manipulate the environment around them, like humans do now. At Class 2, beings change  themselves to fit their environment, using tools such as genetic modification.

And finally at Class 3, the  researchers envision a civilization fully integrating itself with the environment. Merging its technology with living things, and maybe even creating new  thinking creatures from scratch. Another proposed scale classifies  a civilization based on the scale of disaster you’d  need to totally wipe it out: from a local spot on a single planet,  like a city state, to an entire galaxy.

In which case, your civilization  would essentially be immortal… awaiting the heat death of the universe. Assuming you manage to keep it as one big, single civilization that whole time. Which I don’t know how you’d to do.

Humanity is currently sitting on  the third level of this scale, where a global disaster like a  large asteroid impact could end us. And for the last example that we  have time to mention in this episode, there’s the Barrow Scale,  which proposes that instead of thinking big to measure our  progress, we should think small. This scale measures a civilization’s ability to manipulate smaller and smaller objects.

It begins with creatures being  capable of manipulating objects on the scale of themselves, then  the scale of their genes. Then molecules, then atoms, nuclei,  elementary particles like quarks… and then finally, the fundamental  structure of spacetime itself. So the Kardashev Scale is just one  way to describe a civilization.

And despite what some tech bro might tell you, a higher number isn’t necessarily better. After all, if some civilization  had gone Type-III on the Milky Way before we got here, we probably  never would have happened. They probably would have wiped us out!

The Kardashev Scale does not take  into account important aspects of civilization like social equity, environmental  harmony, or disaster resilience. But it can help tell us a lot  about ourselves, what we value as a civilization, and what ultra-long  term goals we want to work towards. And at the very least, it’s  an easy way to think about what alien civilizations might be out there… that could be constructing  their own scales right now, Wondering– just wondering  if, perhaps, we’re out here. [♪OUTRO]