"Grey Goo" is a hypothetical scenario in which self-replicating nanobots consume all matter on Earth while creating copies of themselves. This concept raises concerns about the potential dangers of advanced nanotechnology, particularly if these machines malfunction or are misused. The term was popularized by computer scientist Eric Drexler in his 1986 book, Engines of Creation. In this scenario, the nanobots would break down organic and inorganic materials to create more nanobots, leading to an uncontrollable chain reaction that could threaten life as we know it.