What Is the Kardashev Scale? Understanding Type 0.73

The Kardashev scale compares civilisations by the power they use. The familiar 0.73 example uses a later continuous version and a rounded human power input.

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Why the version matters

Nikolai Kardashev proposes the original scale in 1964. It helps discuss the power available to hypothetical extraterrestrial civilisations and their signals.

Its original Type I benchmark lies near humanity's power use at that time. The later version associated with Carl Sagan sets a much higher Type I benchmark. The Short's below-step-one statement refers to that later version.

Type I and the sunlight comparison

The continuous version puts Type I at 10^16 watts. A watt measures energy transfer per second. The notation represents one followed by sixteen zeros.

The video compares annual human energy use with incoming sunlight. Earth intercepts about 174 quadrillion watts of sunlight at the top of its atmosphere. At that rate, about 600 exajoules arrives in roughly 58 minutes.

An exajoule is 10^18 joules of energy. The comparison uses a rounded annual-energy example, not the output of solar panels. Reflection, night, weather, and conversion losses reduce practical collection.

Type II and stellar power

Type II concerns the power of a star. The continuous formula places its benchmark at 10^26 watts, while actual stars have different outputs.

Freeman Dyson's idea motivates a swarm of collectors around a star. Separate orbiting collectors differ from a rigid solid shell. The energy they use must eventually leave a sustained system as heat.

This motivates infrared searches for some possible technological signatures. A warm infrared source does not prove technology, because natural dust can also emit strongly.

Type III and the size of each step

Type III concerns a galaxy's power scale. Its continuous benchmark is 10^36 watts. The ratio between successive integer levels is exactly ten billion in this formula.

The Short says “at least” because it mixes broad physical examples with the numerical scale. For the stated formula, ten billion is the defined ratio. A particular star or galaxy need not equal its round benchmark exactly.

Calculating 0.73

Use 19 trillion watts as an illustrative human input. Take its base-ten logarithm, subtract six, and divide by ten. The result is about 0.728, or 0.73 after rounding.

That number is not a percentage of a normal progress bar. The logarithmic scale compresses enormous power differences into small numerical changes. It also depends on the definition and date of the energy input.

This article does not treat the rounded input as an independently verified current annual total. It explains the calculation used in the video.

The growth example

At constant growth of 2 percent each year, 19 trillion watts reaches 10^16 watts after about 316 years. The Short rounds this to about three hundred years.

The result assumes uninterrupted compounded growth and the same target definition. It is not a forecast that society must follow. Technology, efficiency, environmental limits, and choices can change the path.

What this means

The scale measures power, not wisdom or quality of life. A useful comparison states its version, input, and assumptions before interpreting the resulting type.

FAQ

Has humanity failed the original Type I definition?

The original and modern benchmarks differ. A comparison must identify which one it uses.

Does 0.73 mean 73 percent of the required power?

No. The scale is logarithmic, and the illustrative input is far below the modern Type I power.

Is the three-hundred-year result guaranteed?

No. It follows from a constant-growth assumption.