In 1964 an astronomer proposed ranking civilisations by one number: how much energy they command.
On that scale, humanity has not yet reached the first rung.
Reaching it is the largest project our species could set itself. We think it should.
Nikolai Kardashev was looking for a way to think about signals from other civilisations. He sorted them by the energy they could put into a transmission. Type I commands the energy available on its planet. Type II commands the output of its star. Type III commands the output of its galaxy.
Carl Sagan later turned the three steps into a continuous number, so that a civilisation in between could be placed. Take the power it uses in watts, take the logarithm, subtract six and divide by ten. Each full step on the scale is ten billion times the last. Each tenth of a step is ten times the last.
Kardashev defined three types and no more. Later writers added a Type 0 for anything below the first rung, and Types IV and V for a civilisation drawing on a whole universe or several. Others have proposed ranking by information mastered, or by how small a scale a civilisation can engineer. Those are extensions by other hands; the energy scale with three types is the original.
Each type is ten billion times the one before. The chart can only show this on a scale where every line is ten times the last.
Source: Kardashev, Transmission of Information by Extraterrestrial Civilizations, Soviet Astronomy (1964); Sagan, The Cosmic Connection (1973), for the continuous formula; Energy Institute 2024 for current use
Each tick is ten times the last, and each full type is ten billion times the one before. Humanity has crossed about seven-tenths of the first interval. The Sun itself sits just past Type II and the Milky Way just past Type III, which is how the thresholds were chosen.
Source: Kardashev (1964); Sagan (1973); Energy Institute 2024 for humanity; solar luminosity from the IAU nominal value; the galaxy's luminosity is approximate
Humanity used 620 exajoules of primary energy in 2023. Spread over the year, that is 19.6 trillion watts. Sagan's formula gives 0.729.
The number moves slowly because the scale is logarithmic. In 1900 we were at about 0.61. When Sagan did the calculation in 1973 the answer was 0.7. A century and a quarter of industrial growth has moved us a little over a tenth of a step.
To reach 1.0 we would need about 510 times the energy we use today.
Fourteen times more energy than in 1900 has raised the number by 0.12.
Source: Derived with Sagan's formula from historical primary energy estimates (Smil, Energy Transitions) and the Energy Institute Statistical Review 2024 · cited from memory, to verify
A Type II or Type III civilisation should be visible. Energy that is used ends up as waste heat, so a star or a galaxy being harvested would glow strangely in the infrared. Astronomers have looked.
One survey examined about 100,000 galaxies for that glow and found none that looked like a galaxy-spanning civilisation. A 2024 search through about five million nearby stars turned up seven with unexplained infrared excess; follow-up observations suggest that at least some are ordinary background galaxies that happen to sit behind the star.
So the honest count is this. Known Type III civilisations: zero. Known Type II: zero. Known Type I: zero. Known civilisations of any kind: one, at 0.73. Absence of evidence in a search this young is not proof, but it does mean there is no one ahead of us that we know of to copy.
These are the results of the two largest searches for the waste heat a great civilisation could not hide. The seven candidates are probably ordinary: follow-up work suggests distant galaxies lying behind the stars. The count that matters is the last one.
Source: Griffith et al. (2015) for the galaxy survey; Suazo et al. (2024) and Ren et al. (2024) for the stellar search · cited from memory, to verify
Ten thousand trillion watts is about 6% of the sunlight that reaches the Earth. That is the first clue about how it has to be done.
All energy that is used ends as heat. If a Type I supply were generated on Earth from sources the planet would not otherwise receive, such as fusion, fission or fuels, the waste heat alone would warm the surface by about 20 watts per square metre. Doubling the carbon dioxide in the atmosphere adds about 4. No climate we would recognise survives that.
There are two ways through. Capture sunlight that was going to warm the planet anyway, which adds almost nothing. Or move heavy industry, and its heat, off the planet. A real path to Type I uses both, and it makes the five other fields of this plan necessary: energy to supply it, robotics to build it, AI to run it, and biology and cybernetics so that people thrive in it.
The outer square is all the sunlight that reaches the Earth. The grey square is a Type I supply: about six per cent of it. The white square, almost too small to see, is everything humanity uses now. This is why the plan leans on capturing sunlight. The energy is already arriving, and using it adds no new heat to the planet.
Source: Derived from the solar constant (1,361 W/m²) and the Earth's cross-section; Energy Institute 2024 · cited from memory, to verify
Our aim is to help humanity become a Type I civilisation, and to do it without wrecking the one planet we have. We use the Kardashev number as a compass, not a scoreboard: a civilisation is not good because it uses energy, but almost nothing good at scale can be done without it.
At 2% growth a year the arithmetic says three centuries. That is not a forecast. It is the size of the task at the pace we have managed so far, and the pace is ours to change.
Set how fast energy use grows and where the energy comes from. The chart shows when humanity crosses 1.0. The heating figure shows what the planet would be dealing with on arrival.
This is a statement of intent, not a record of achievement. Each step carries a label for how firm it is. Nothing marked proposed or speculative has been done yet.
19.6 trillion watts, 81.5% of it from fossil fuels.
Replace the fossil four-fifths, then keep growing. Several times today's supply would put us near 0.8.
Capture a meaningful fraction of a per cent of incoming sunlight; move the most heat-intensive work into orbit.
Ten thousand trillion watts under human direction, with the Earth's climate held stable by design.
Ten billion times further. Collectors around the Sun. A project for a civilisation that has already succeeded at this one.
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