Contact Inequality -- First Contact Will Likely Be With An Older Civilization

TL;DR

The paper argues that first contact with extraterrestrial intelligences will likely be with older civilizations due to a selection effect, leading to contact inequality similar to wealth disparity, which impacts SETI strategies.

Contribution

It introduces a formal model showing that the probability of contact favors older civilizations, highlighting a bias in first contact scenarios.

Findings

Detected intelligences will have a mean age twice that of the population.

First contact is most likely with civilizations older than our own if their maximum lifetime exceeds e times ours.

Older civilizations, though rare, disproportionately influence initial contact probabilities.

Abstract

First contact with another civilization, or simply another intelligence of some kind, will likely be quite different depending on whether that intelligence is more or less advanced than ourselves. If we assume that the lifetime distribution of intelligences follows an approximately exponential distribution, one might naively assume that the pile-up of short-lived entities dominates any detection or contact scenario. However, it is argued here that the probability of contact is proportional to the age of said intelligence (or possibly stronger), which introduces a selection effect. We demonstrate that detected intelligences will have a mean age twice that of the underlying (detected + undetected) population, using the exponential model. We find that our first contact will most likely be with an older intelligence, provided that the maximum allowed mean lifetime of the intelligence population, $\tau_{\rm max}$, is $>e$ times larger than our own. Older intelligences may be rare but they disproportionality contribute to first contacts, introducing what we call a 'contact inequality', analogous to wealth inequality. This reasoning formalizes intuitional arguments and highlights that first contact would likely be one-sided, with ramifications for how we approach SETI.