The Interstellar Laser Beacons Hypothesis and the Cosmic Lighthouses Project

In this paper, we argue that in a realistic, resource-limited scenario senders whose intent is to maximize successful communication at the lowest cost will utilize very long-lived, pulsed beacons. Further, we argue that mass-producible laser beacons with simpler technology ($\mu$s or ms pulses instead of ultrashort fs pulses) are more optimal if placed on interstellar orbits. Our extensive, existing surveys are mostly blind to the $\mu$s/ms-second universe and to such beacons. We show, however, that the convergence of three technologies (massively parallel processing, ultra high-speed CMOS detectors, and broadband, mass-producible diffractive-refractive lenses) now offer an exciting opportunity for a low-cost survey of the $\mu$second sky. Such survey would be astrophysically compelling and, with even low-cost telescopes, could place volume-complete constraints on interstellar beacons within twenty parsecss.