A brief history of the search for extraterrestrial intelligence and an appraisal of the future of this endeavor

TL;DR

This paper reviews the history and progress of the search for extraterrestrial intelligence, highlighting technological developments, key efforts, and future prospects in this scientific endeavor.

Contribution

It provides a comprehensive overview of past and recent radio searches for ETI, emphasizing technological advancements and influential search strategies.

Findings

Radio searches have been conducted by over sixty groups without detecting ETI signals.

Most searches lacked high sensitivity, explaining the absence of detections.

Recent more sensitive searches and innovative methods have advanced the field.

Abstract

The idea that credible searches for Extra-Terrestrial Intelligence (ETI) could be carried out were laid out in detail in the (now classic) paper by Morrison and Cocconi (1959). They suggested using the radio band for these searches. Since then radio searches have been carried out by over sixty different groups. No signals from ETI's have been identified. Most searches did not have high sensitivity and it is not surprising that ETI signals were not detected. It is important to note, however, that these efforts were instrumental in developing new technical capabilities and they helped generate wide interest in this field. In this paper I will briefly discuss the more sensitive searches that have been carried out and some of the other searches that are arguably quite innovative or have been influential in some other manner.