13th May 2022 | Life Elsewhere

This month’s blog looks at what kind of civilisations could populate the universe. There are definitions for them, most of them rather mind-boggling, nevertheless let’s see what we have.

The Kardashev Scale

The Kardashev scale is a system for measuring a civilisation’s level of technological advancement based on the amount of energy it is able to use. The scale was originally proposed by Soviet astronomer Nikolai Kardashev in 1964, so it goes back quite some way.

The scale is hypothetical, and regards energy consumption on a galactic scale. Various extensions of the scale have since been proposed, including a wider range of power levels (types 0, IV to VI) and the use of metrics other than pure power.

But let’s have a look at the system as initially defined. Just use the numbers for a comparison.

 Type I

A civilisation close to the level presently attained on Earth, with energy consumption at 4×1012 watts [≈4×1019 erg /sec]. A Type I civilisation is usually defined as one that can harness all the energy that reaches its home planet from its parent star—for Earth, this value is around 2×1017 watts—which is about four orders of magnitude higher than the amount presently attained on Earth, with energy consumption at ≈2×1013 watts as of 2020. So we really have some way to go yet. Use of solar energy will obviously increase this figure. But how can our energy use possibly get any higher?

Type II

A civilisation capable of harnessing the total energy radiated by its own star—for example, by means of the successful installation of a Dyson sphere, which is a hypothetical megastructure that completely encompasses a star and captures a large percentage of its solar output. Energy consumption is at ≈4×1033 erg/sec.

I guess we can tell where this is going now.

Type III

A huge step! A civilisation in possession of energy at the scale of its own galaxy, with energy consumption at ≈4×1044 erg/sec. Civilisations of this type would have access to power comparable to the luminosity of the entire Milky Way galaxy, about 4×1044 erg/sec (4×1037 watts).

Extensions to the original scale

New types (0, IV, V and VI) have been proposed.

The most straightforward extension of the scale to even more hypothetical Type IV beings who can control or use the entire universe i.e. all galaxies. Or Type V who control collections of universes. This would also include Type 0 civilizations, who do not rank on the Kardashev scale. The power output of the visible universe is within a few orders of magnitude of 1045 W. Such a civilization approaches or surpasses the limits of speculation based on current scientific understanding and may not be possible.


No matter how you look at it, it seems we are right at the beginning of galactic possibilities. The amount of energy out there in the universe is huge. To even imagine humankind harnessing the full potential of our sun involves a giant step of credibility.

References and Further Reading   [10 minutes]


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