Stars and milky way in the beautiful night sky

There is most probably no Kardashev Type III civilization in the Universe. Here’s why.

In 1964, Russian astrophysicist Nikolai Kardashev (April 25, 1932 – August 3, 2019) defined three levels of civilizations, based on the order of magnitude of power available to them (known as the Kardashev scale):

The Kardashev Scale

Type I

A Type I civilization, also called a planetary civilization can use and store all of the energy available on its planet. For the Earth-Sun system, this value is close to 7×1017 watts.

Type II

Also called a stellar civilization – a civilization capable of harnessing the energy radiated by its own star. Our Type I brains can hardly imagine how someone would do this, but we’ve tried our best, imagining things like a Dyson Sphere. The successful construction of a Dyson sphere would make a civilization’s status Type II, with energy consumption at ≈4×1033 erg/sec.

Type III

A civilization in possession of energy on the scale of its own galaxy, with energy consumption at ≈4×1044 erg/sec for our galaxy, the Milky Way.

Human Civilization on the Kardashev Scale

For context, recent studies suggest that Humanity presently stands at Type 0.7276 on the Kardashev Scale. Even in 2060, humanity will become only a Type 0.7449 civilization. [Study: Forecasting the progression of human civilization on the Kardashev Scale through 2060 with a machine learning approach. Zhang, A. et al.]

There is most probably no Kardashev Type-III civilization in the Universe

Some scientists suggest Kardashev Type III civilizations could be here, all around us, but we’re just too primitive to perceive them. American physicist Michio Kaku says: “Let’s say we have an ant hill in the middle of the forest. And right next to the anthill, they’re building a ten-lane super-highway. And the question is ‘Would the ants be able to understand what a ten-lane super-highway is? Would the ants be able to understand the technology and the intentions of the beings building the highway next to them?’”

There are problems with this viewpoint. An ant doesn’t know what a highway is because it doesn’t know what anything is. It’s not that highways are too complicated for ants to understand, it’s that “understanding things” isn’t what an ant’s brain does.

We could recognize a Kardashev Type III civilization if we saw one

Even if we can’t understand what it is, or what they are doing, we could recognize a Type III civilization if we saw one. If a super-advanced alien civilization was doing some indescribable thing over there, we’d at least be able to say “Wow, that is some bizarre thing happening over there. We have no idea what that thing is, though”.

A Type III civilization’s activities might manifest in phenomena observable across cosmic distances, such as altering or stabilizing dangerous space objects, engineering stars for specific purposes, or even creating or manipulating black holes. We might detect unusually patterned energy emissions, deliberate stellar movements, or artificial megastructures, like Dyson Spheres, encasing stars to capture their energy output.

A Kardashev Type 3 civilization is one that has mastered the energy resources of an entire galaxy
A Kardashev Type 3 civilization is one that has mastered the energy resources of an entire galaxy, harnessing and controlling energy on a galactic scale. This advanced civilization would possess the technological capabilities to manipulate galactic structures and draw power from millions, or even billions of stars, far beyond current human capabilities.

Such civilization could also be involved in large-scale space terraforming or interstellar travel using technologies that bend the fabric of space-time, visible through anomalies in gravitational waves or light patterns. The sheer scale of these undertakings would likely produce detectable signatures, even if their purposes or methods elude our current scientific understanding, leading to observations of extraordinary cosmic phenomena that defy natural explanations, prompting a mixture of awe and bafflement among human observers.

Essentially, their huge engineering feats and energy manipulation on a galactic scale could introduce observable changes in the cosmic background or alter the fundamental astrophysical constants in localized regions of space, offering us clues to their existence and the extent of their capabilities.

In other words, a Type III civilization like Kardashev imagined should stick out like a sore thumb.

A single civilization simply cannot colonize an entire galaxy

Because it would not be practical.

The vast distances within a galaxy present insurmountable challenges for a single civilization aiming for galactic colonization under the constraints of current physics.

For example, the Milky Way’s immense scale (it is about 100,000 light-years across) means that even at light speed, communication and travel across the galaxy are practically untenable. Keep in mind that nothing can go faster than light, so we cannot communicate faster than that.

So, sending messages back and forth on either side of the galaxy would take hundreds of thousands of years. We know that cultures and languages change dramatically over just a few hundred years – even on the same planet! In a galactic civilization’s case, after many thousands of years, the receivers even may no longer have any idea how to decipher the message. They can be even an entirely new species after that long time.

In other words, this temporal disconnect would lead to civilizations on different ends of the galaxy evolving independently, with potentially divergent technological, cultural, and biological paths.

Over millennia, these isolated pockets of civilization could become so distinct that they effectively function as separate entities, making the idea of a unified galactic civilization more of a federation of related yet fundamentally different civilizations rather than a single, cohesive entity.

Additionally, the energy requirements for sustaining a presence across such vast distances would be astronomical, necessitating advances in energy production and utilization far beyond our current capabilities.

The concept of a “galactic civilization” thus might be reimagined as a network of loosely affiliated civilizations, each adapted to their unique sectors of space, rather than a single empire spanning the stars. This perspective underscores the enormity of galactic scales and the profound implications for the future evolution of intelligent life within such immense cosmic structures.

Even colonizing the next star system is practically impossible (as a single civilization)

The concept of colonizing even our nearest star system, such as Alpha Centauri, presents formidable challenges that extend beyond the realms of engineering and astrophysics into the domain of evolutionary biology and sociology. Assuming the creation of a generation ship-a colossal spacecraft designed to sustain human life across millennia-the voyage to Alpha Centauri could span several thousand years.

Over such prolonged periods, isolated from Earth in a unique environment, the initial colonizers and their descendants would undergo significant cultural, linguistic, and even biological changes. The pressures of their new surroundings, coupled with the absence of Earth’s specific selection pressures, could accelerate evolutionary divergence, potentially leading to the emergence of a new human species.

This newfound species, shaped by its environment and experiences, would likely view the directives and governance of distant Earth-bound humans as irrelevant, choosing instead to establish their own societal norms, governance, and civilization. The concept challenges our understanding of human unity and governance across vast distances and time scales, underscoring the complexities of space colonization not just as a technological endeavor, but as a profound venture into the unknown future of human evolution and identity.

It would be immoral to send out a Generation Starship

The concept of a generation ship for interstellar travel raises profound moral questions, particularly concerning the rights and well-being of individuals born during the voyage. These individuals, destined to live their entire lives within the confined spaces of a spacecraft, would have no choice in their participation in the mission. Unlike their ancestors who might have volunteered for the journey, these generations would be born into a reality they never elected, confined to a limited area without the possibility of experiencing Earth, its vast ecosystems, or the freedom to explore beyond the ship’s boundaries.

This scenario prompts ethical considerations about autonomy, consent, and quality of life. Is it just to subject generations to a life predetermined by decisions made centuries before their birth? Moreover, the psychological and social implications of living in such an environment are significant. Human beings thrive on variety, exploration, and connection with natural elements that would be inherently limited or artificial within the ship.

Furthermore, the moral responsibility of the initiating generation includes ensuring the ship provides a life worth living for its inhabitants, which encompasses more than physical survival. It involves fostering a healthy, vibrant culture, opportunities for fulfillment, and a sense of community and purpose. The challenge lies in creating a self-sustaining environment that not only supports life but nurtures human dignity, freedom, and happiness, questioning the very nature of progress and the ethical boundaries of exploration.

There might be no reason to colonize an entire galaxy for an advanced civilization

Once a civilization reaches a Kardashev Type II status, encapsulating its star with a Dyson sphere or swarm to harness its full energy output, the need for physical expansion could indeed diminish significantly. Such a civilization, having transitioned to a post-biological existence, with consciousness uploaded into a virtual reality that offers an idyllic, eternal existence, might view the physical universe in a fundamentally different light.

In this virtual existence, the concepts of space, territory, and resource scarcity could become obsolete, replaced by an infinite digital landscape where the limitations of the physical world no longer apply. The risks associated with interstellar travel, such as the vast distances, the potential for catastrophic failure, and the uncertainty of finding habitable or terraformable worlds, might seem unnecessary gambles compared to the safety and certainty of their digital realms.

However, the sustainability of their Dyson sphere or the lifespan of their host star could necessitate eventual expansion. Even for a machine civilization, the death of a star and the eventual need to find new energy sources could drive them to explore and potentially colonize new systems. Yet, their approach to colonization might be radically different, focused on harnessing energy rather than inhabiting planets. They could deploy autonomous probes to construct new Dyson swarms around other stars, gradually expanding their energy network across the galaxy in a slow, methodical process that minimizes risk.

Moreover, such a civilization might also consider the preservation of biodiversity and the ethical implications of interfering with the natural development of other life forms. Their advanced understanding and capabilities could lead to a form of cosmic stewardship, where they protect and study life-bearing planets rather than colonize them, ensuring the galaxy’s vast tapestry of life flourishes under their watchful, but non-intrusive, guidance. This perspective shift from conquest to guardianship reflects a profound evolution in the civilization’s priorities and values, emphasizing harmony with the universe over domination.

Variants of the Kardashev Scale

There are five and six-level variants of the Kardashev scale.

Carl Sagan, for example, suggested a new formula. As a result of his formulation, there should be a “Type 0” civilization, which controls almost no power on their home planet. As of 2024, humanity was at 0.7276 level on Sagan’s Kardashev scale.

At the other end of the scale, there are Type IV and Type V civilizations. A Type IV civilization can harness the energy of an entire Universe. A Type V civilization can control the multiverse, a collection of Universes. These two are highly speculative, and we see no evidence of them (obviously).

Energy consumption of three types of civilization as defined by Carl Sagan's extended Kardashev scale.
Energy consumption of three types of civilization as defined by Carl Sagan’s extended Kardashev scale.

Read more

In 2015, a study of galactic mid-infrared emissions concluded that “Kardashev Type-III civilizations are either very rare or do not exist in the local Universe”.


  • Kardashev scale on Wikipedia
  • Fermi Paradox on Wait But Why
  • “Oxford Scientists Suggest That Aliens Aren’t Extinct, Just Hibernating. Extraterrestrials may be biding their time, waiting for a more ideal universe” on Futurism
  • Forecasting the progression of human civilization on the Kardashev Scale through 2060 with a machine-learning approach. Zhang, A. et al. [pubmed]
M. Özgür Nevres


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