The "Grabby Alien" hypothesis posits that as alien civilisations grow technologically and expand their reach, they gradually draw nearer to Earth and other civilisations, converging across vast distances in space. This idea suggests that over time, the likelihood of encountering such civilisations increases, potentially leading to a higher chance of extraterrestrial sightings on Earth.

Within this theory, so-called "loud" aliens expand their sphere of influence in a highly detectable way, and "quiet" aliens are hard or impossible to detect. "Grabby" aliens are loud aliens that inhibit the development of other technological civilisations within their sphere of influence.

The hypothesis begs two questions: (1) what are the chances that alien civilisation(s) have grown to converge on Earth and (2) what are the chances we would be able to detect them?

Approximating the likelihood of contemporary alien sightings being genuine extraterrestrial contact requires balancing advancements in our understanding of space, technological convergence of far-away civilisations, and the limits of human perception.The Grabby Alien hypothesis provides a reference frame from which to start narrowing down the likelihood of contemporary alien sightings.