Nikolai Kardashev’s 1964 classification of civilisations by the energy they command: Type I using the energy available on a planet, Type II the output of a star, Type III that of a galaxy. Carl Sagan later gave it a continuous form so that a civilisation could sit between the integers; on that measure ours is somewhere below Type I.
What it was for
It was a radio astronomer’s tool, built to bound the detectability of a transmitter rather than to describe a developmental path. Its useful property is that energy budgets are physics and not sociology: whatever an advanced civilisation wants, it cannot get around thermodynamics, which is why the scale keeps returning in SETI search strategy and in the Fermi paradox literature, and why Dyson’s original 1960 proposal was about infrared waste heat rather than about megastructures as such.
The uses it gets put to
The Jorjani - Danny Jones Podcast 2025 interview proposes that the simulation contains an engineered ceiling preventing any civilisation from passing roughly Type II, offered as a resolution of the Fermi paradox. That is a hypothesis about the scale rather than a result from it, and the scale itself carries no implication that anything limits the climb.
Connections
SETI · Avi Loeb · Jorjani - Danny Jones Podcast 2025 · Zero-Point Energy · Silurian Hypothesis · Simulation Argument · Directed Panspermia