global ecophagy
(gloh.bul EK.oh.fay.gee) n. The potential destruction of life caused by rampant nanotechnological machines that break down organic matter to use as raw materials for replicating themselves.

Example Citation:
They call it "global ecophagy". That's "eating the Earth" to you and me. Rumour has it that this is what replicating nanostructures might do, and according to one estimate, they could gobble up the entire planet in about three hours flat.
—Philip Ball, "The robot within," New Scientist, March 15, 2003

Earliest Citation:
Nanotechnologists have similarly recognized that out-of-control nanobots could destroy the biosphere; a first quantitative study of this possibility of "global ecophagy" by Robert Freitas was recently published in response to the article I wrote on this subject in Wired in April. His study is quite troubling, showing the clear dangers we face from unrestricted nanotechnology and the extreme difficulty and enormous scale required of any "defense."
—Bill Joy, "Genetics, nanotechnology, robotics pose danger to society," The Sunday Patriot-News Harrisburg, July 23, 2000

First Use:
Perhaps the earliest-recognized and best-known danger of molecular nanotechnology is the risk that self-replicating nanorobots capable of functioning autonomously in the natural environment could quickly convert that natural environment (e.g., "biomass") into replicas of themselves (e.g., "nanomass") on a global basis, a scenario usually referred to as the "gray goo problem" but perhaps more properly termed "global ecophagy."
—Robert A. Freitas Jr., "Some Limits to Global Ecophagy by Biovorous Nanoreplicators, with Public Policy Recommendations," Foresight Institute, April 2000

The ecophagy part of this phrase is a recombination of the prefix eco-, "the environment; ecology," and the suffix -phagy, "eating." So global ecophagy means, literally, the eating of the world's environment.

How could this happen? It's one of the inherent dangers posed by nanotechnology — technology at the scale of a billionth of a meter (or about the width of an atom or two). Nanotechnologists envision (indeed, are working toward) a world in which nano-scale assemblers can be programmed to build anything — cars, cardigans, carving knives, you name it — by manipulating individual atoms (taken from, say, a nearby load of scrap metal or sand). To make this efficient, trillions of these assemblers are required, so the first task is to make assemblers that can forge copies of themselves, so-called replicating assemblers or nanoreplicators.

In a production environment, these replicating assemblers would operate under strict supervision that shuts down the replication process when enough machines have been made. But what would happen if just one of these unimaginably small replicators escaped from this controlled scenario? Without other safeguards in place, possibly the only thing that would stop the machine from making copies of itself is running out of whatever raw materials it needs to perform its work.

Now suppose, however, that the machine is biovorous (literally, life-eating) meaning that it uses organic matter as its raw material. In this case, theoretically, the machine and its offspring would, under certain circumstances, continue replicating until all the world's plant and animal life was consumed: global ecophagy.

This is also known, more vividly, as the gray goo problem, since all that would be left of the world is an undifferentiated mass of nanoreplicators. The problem was first expounded by K. Eric Drexler in his book Engines of Creation:

Among the cognoscenti of nanotechnology, this threat has become known as the "gray goo problem." Though masses of uncontrolled replicators need not be gray or gooey, the term "gray goo" emphasizes that replicators able to obliterate life might be less inspiring than a single species of crabgrass. They might be superior in an evolutionary sense, but this need not make them valuable.

The gray goo threat makes one thing perfectly clear: We cannot afford certain kinds of accidents with replicating assemblers.
—K. Eric Drexler, "Engines of Destruction," Engines of Creation, 1987

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