dyson-sphere

Dyson spheres aren't solid shells — they're swarms of solar collectors around a star. Here's how they'd work, why we'd build one, and how we'd spot aliens using one.

A Dyson sphere — a structure capturing all of the Sun's energy — would harness 3.86 × 10²⁶ watts, more than a trillion times humanity's current power use. Building it requires more material than exists in any individual planet, but could in principle be done by dismantling Mercury or several asteroids.

In 1964, Soviet astronomer Nikolai Kardashev proposed ranking civilizations by the power they command. Type III means a whole galaxy. Humanity sits near 0.73, and the arithmetic of getting from here to Type III is humbling.