Strategies for SETI Through Radio Waves an Introduction

Abstract

A peculiar opposition has developed to SETI. It is argued that, if intelligent civilizations were as common as SETI enthusiasts believe, Earth surely would have been colonized or at least visited long ago. Of course, followers of Von Däniken believe we have been, while the UFO buffs believe we are still being visited. But a more skeptical faction, finding no solid evidence either for visitation or for astro-engineering on a Dyson scale, concludes that either we are being quarantined (the zoo hypothesis) or else intelligent life is a very rare phenomenon (we really are alone).