THE SUPERIOR UTILITY OF LASERS FOR INTERSTELLAR BEACONS, COMMUNICATIONS, AND TRAVEL
John D. G. Rather
Programme Development OACT
Washington DC 20546
Present research supporting the Search for Extraterrestrial Intelligence (SETI) and Communications with Extraterrestrial Intelligence (CETI) is almost entirely focused upon microwave wavelengths and technologies. This paper demonstrates compelling reasons why the search should be broadened to optical wavelengths. Previous calculations of laser transmission efficiency are shown to be incorrect because an essentially lossless laser transmission system is feasible and star noise can be rendered inconsequential. New perceptions regarding the feasibility of laser technologies, together with reassessments of signal-to-noise considerations, indicate both the feasibility and desirability of optical interstellar transmissions, particularly at infrared and visible wavelengths.
Implicit in the rationale for SETI/CETI is the question of ultimate motivations. It is shown that use of the large bandwidths available at optical wavelengths greatly enhances the possible utility of such endeavors. Present astronomical equipment and methods are adequate for the initial detection, with automated wide field spectroscopy being the method of choice. Specially constructed receiving equipment would be required for full decoding of the signals after successful detection. The need for technologies supporting large data transmission bandwidths is coupled with a plausible answer to the classic query, "Why would anybody want to communicate?". It appears possible to transmit intelligent entities between stars at the speed of light.