The Twin Planet Hypothesis is a conceptual thought experiment used to predict when intelligent civilizations elsewhere in the galaxy might begin emitting detectable signals, such as radio waves. The idea imagines a planet nearly identical to Earth—same age, same solar conditions—where intelligent life evolves on a slightly different timeline, for example, 50,000 years behind or ahead of us.

Given Earth’s timeline (approximately 4.5 billion years to reach radio-capable intelligence), this small offset is negligible cosmologically, but significant technologically. This model implies that if humanity is near the median in galactic development, we should expect a “signal bloom” of detectable civilizations to emerge around 50,000 years from now—meaning we are early, and most others are still coming online.