A diagram is a claim. So is a number. Here is where the claims rest.
Nikolai S. Kardashev · 1964 · primary
The original scale. Type I, II, and III were energy classes for thinking about interstellar communication, not moral ranks. Original Type I was about 4 × 10¹² watts.
Freeman J. Dyson · 1960 · primary
Dyson asked whether a civilization might collect starlight with many orbiting objects and whether leftover heat would shine in the infrared. The popular “solid sphere” is a later oversimplification.
Dyson and later commentators · 1960– · standard
Independent collectors in orbit are physically more plausible than a rigid shell. This app treats swarm as the careful picture and sphere as the cartoon.
Carl Sagan · 1973 · standard
Sagan wrote a smooth formula so civilizations could have in-between values. Humanity is often quoted near 0.7. Treat the decimal as a sketch.
IEA and related energy statistics · 2020s · standard
Human primary energy use is on the order of 20 trillion watts. Numbers move year to year. We use order of magnitude, not a fake exact watt.
Solar constant and planetary geometry · measured · standard
Earth intercepts about 1.7 × 10¹⁷ watts of sunlight. Albedo reflects a fraction. This is the river of power behind popular Type I talk.
Physics · standing result · standard
Energy changes form. It is not destroyed. Work becomes heat. This is why waste-heat searches exist.
Dyson; later infrared surveys · 1960– · survey
A star with extra mid-infrared light might be dusty, or might be re-radiating used energy. A glow is a clue, not a civilization.
SETI and related programs · living · survey
Possible fingerprints of technology: radio, lasers, industrial gases, waste heat, unusual light curves. Searches, not discoveries.
Jason T. Wright and collaborators · 2010s · survey
Infrared surveys looking for galaxy-scale or stellar-scale waste heat. Results so far: no confirmed swarms. Limits are themselves a finding.
Citizen scientists and follow-up astronomy · 2015– · survey
Strange brightness dips invited swarm talk. Later work has favored dust and other natural ideas. Weird is not enough.
Satellite night-light imaging · living · standard
City lights are a real energy fingerprint of us. They measure activity, not goodness.
Laboratory programs worldwide · living · survey
Fusion is the Sun’s family of fire, attempted in machines. Progress is real. Affordable plants are not here yet.
Galactic astronomy · standing · standard
On the order of 100 billion stars, about 100,000 light-years across. Type III energy talk must live with that delay.