Intelligent Responses to Our Technological Signals Will Not Arrive In Fewer Than Three Millennia

TL;DR

The paper argues that intelligent responses from extraterrestrial civilizations are unlikely to arrive in fewer than three millennia due to the vast distances and response times involved, based on probabilistic and principle-based reasoning.

Contribution

It provides a probabilistic analysis and a theoretical lower bound on the response time for extraterrestrial signals based on the Copernican principle.

Findings

Response times are expected to be at least a few millennia.

The likelihood of early responses is extremely low.

Longer civilization durations increase response probability.

Abstract

What is the chance we start a conversation with another civilization like our own? Our technological society produced signals that could be received by other extraterrestrial civilizations, within a sphere around us with a radius of $\sim 10^2$ light years. Given that, the Copernican principle provides a lower limit on the response time that we should expect from transmitters on Earth-like planets around Sun-like stars. If our civilization lives longer, the expected number of responses could increase. We explore the chance of detecting a response in the future, and show that a response should only be expected to arrive after a few millennia.