Grey goo

Grey goo refers to a hypothetical end-of-the-world event involving molecular nanotechnology in which out-of-control self-replicating robots consume all living matter on Earth while building more of themselves (a scenario known as ecophagy).

The term is usually used in a science fiction context. In a worst-case scenario, all of the matter in the universe could be turned into goo (with "goo" meaning a large mass of replicating nanomachines lacking large-scale structure, which may or may not actually appear goo-like), killing the universe's inhabitants. The disaster is posited to result from an accidental mutation in a self-replicating nanomachine used for other purposes, or possibly from a deliberate doomsday device.

Definition of grey goo

The term was first used by molecular nanotechnology pioneer Eric Drexler in his book Engines of Creation (1986). In Chapter 4, Engines Of Abundance, Drexler explores a scary scenario of exponential growth with such assemblers:

"Thus the first replicator assembles a copy in one thousand seconds, the two replicators then build two more in the next thousand seconds, the four build another four, and the eight build another eight. At the end of ten hours, there are not thirty-six new replicators, but over 68 billion. In less than a day, they would weigh a ton; in less than two days, they would outweigh the Earth; in another four hours, they would exceed the mass of the Sun and all the planets combined - if the bottle of chemicals hadn't run dry long before."

Drexler describes grey goo in Chapter 11 Engines Of Destruction:

"...early assembler-based replicators could beat the most advanced modern organisms. "Plants" with "leaves" no more efficient than today's solar cells could out-compete real plants, crowding the biosphere with an inedible foliage. Tough, omnivorous "bacteria" could out-compete real bacteria: they could spread like blowing pollen, replicate swiftly, and reduce the biosphere to dust in a matter of days. Dangerous replicators could easily be too tough, small, and rapidly spreading to stop - at least if we made no preparation. We have trouble enough controlling viruses and fruit flies."

It is thus worth noting that grey goo need not be grey or gooey. They could be like, for all purposes, a plant or bacteria. It is only the result of their ecophagy that would resemble grey goo.

Living goo

One convenient analogy for the grey goo problem is to consider bacteria as the most perfect example of biological nanotechnology. As they have not reduced the world to living goo, some consider it unlikely that some artificial construct will manage to do so with grey goo.

Even so, some people argue that living goo, or even a combination of nanotechnology and biotechnology to create organic replicators, is a more realistic threat than grey goo. Arguing that bacteria are ubiquitous and extraordinarily powerful, Bill Bryson (2003) says that the Earth is "their planet" and that we're only allowed to exist on it because "they allow us to". Margulis and Sagan (1995) go further, arguing that all organisms, having descended from bacteria, are in a sense bacteria. Many kinds of bacteria are in fact essential for human life and are found in large quantities in the human digestive tract, in a symbiotic relationship.

Thus a living goo could be a multicellular organism that obtains its raw materials to grow through ecophagy, and then grows through a process of exponential assembly such as cell division.

Risks and precautions

It is unclear whether the molecular nanotechnology would be capable of creating grey goo at all. Among other common refutations, theorists suggest that the very size of nanoparticles inhibits them from moving very quickly. While the biological matter that composes life releases significant amounts of energy when oxidised, and other sources of energy such as sunlight are available, this energy might not be sufficient for the putative nanorobots to out-compete existing organic life that already uses those resources, especially considering how much energy nanorobots would use for locomotion. If the nanomachine was itself composed of organic molecules, then it might even find itself being preyed upon by preexisting bacteria and other natural life forms.

If nanorobots were built of inorganic compounds or made much use of elements that are not generally found in living matter, then they would need to use much of their metabolic output for fighting entropy as they purified (reduce sand to silicon, for instance) and synthesized the necessary building blocks. There would be little chemical energy available from inorganic matter such as rocks because, aside from a few exceptions (coal, for example) it is mostly well-oxidized and sitting in a free-energy minimum.

Assuming a molecular nanotechnological replicator were capable of causing a grey goo disaster, safety precautions might include programming them to stop reproducing after a certain number of generations (but see cancer), designing them to require a rare material that would be sprayed on the construction site before their release, or requiring constant direct control from an external computer. Another possibility is to encrypt the memory of the replicators in such a way that any changed copy is overwhelmingly likely to decrypt to non-functioning static.

In Britain, the Prince of Wales called upon the Royal Society to investigate the "enormous environmental and social risks" of nanotechnology in a planned report, leading to much delighted media commentary on grey goo. The Royal Society's report on nanoscience was released on 29 July 2004.

Recently, new analysis has shown that the danger of grey goo is far less likely than originally thought. However, other long-term major risks to society and the environment from nanotechnology have been identified. Drexler has made a somewhat public effort to retract his grey goo hypothesis, in an effort to focus the debate on more realistic threats associated with knowledge-enabled nanoterrorism and other misuses.

Famous quotes

"We cannot afford certain types of accidents", Eric Drexler, Engines of creation, 1986
"I wish I had never used the term 'grey goo'", Eric Drexler, Nature 10 June 2004

Fictional depictions

In books

Autofac is a 1955 science fiction short story by Philip K. Dick that features one of the earliest treatments of self-replicating machines.

In Stanisław Lem's Ciemność i Plesń (Darkness and Mildew), 1959, spores of an engineered lifeform that can use nuclear energy escape the lab. In order for the spores to activate, they need to be in the dark and near a rare species of mildew (hence the title), after which they grow exponentially.

In Michael Crichton's The Andromeda Strain, (1969) also made into a movie, a rapidly evolving virus/prion-like chemical consumes many types of organic molecules with catastrophic results. This story overlaps both the grey goo and the out-of-control virus scenarios. The same author's Prey, (2002) presents a somewhat less limited scenario where a company in Nevada accidentally/purposely releases self-assembling nanobots into the desert, which quickly replicate and evolve and threaten all of the human protagonists.

The plot of John Sladek's 1968 novel The Reproductive System is based on small (but not nano-scale) machines who scour the world for material to make more of themselves. The phrase "grey goo" is not used but the idea is the same.

In the Adam Warren-penned Dirty Pair manga, (1979-) mankind has ventured out into the stars as a result of the Nodachi Nanoclysm (often referred to as just "the Nanoclysm"), where nano absorbed the majority of the solar system before gaining sentience and annihilating itself to save its creators. As a result, with rare exceptions, nanotechnology is universally banned in human civilizations.

Greg Bear's novel Blood Music (1983) is a classic of the field, depicting a form of grey goo originally derived from human lymphocytes.

Frank Miller's graphic novel, Ronin, (1983-84) is set in a future New York which is being overtaken by a post-singularity computer complex capable of physically replicating itself.

Alan Moore's comic book, Promethea, takes place in a technologically-futuristic modern world, where the synthetic "Elastagel" is ubiquitous. In one issue, a Y2K malfunction causes all the Elastagel to melt and run together, essentially creating a Blob-like creature that causes havoc before being destroyed by the protagonist.

In Jeffrey Carver's 1989 novel, From a Changeling Star, medical NAGs (nano-agents) capable of healing a human body from severe trauma run dangerously amok, causing amnesia and bizarre behavior. Competing NAGs, known collectively as an intelligence named Dax, help to reconstruct the memories and reveal a conspiracy regarding an attempt to cause Betelgeuse to go supernova.

Walter Jon Williams's novel Aristoi (1993) featured a future wherein Earth was consumed and destroyed by runaway nano, referred to as "mataglap", from an Indonesian expression, "Mata Gelap," meaning "cloudy eye," "dark eye," or "dilated eye." Mata Gelap is considered to be an indication that one is blind to reason, and possibly about to run amok.

In Ken Macleod's The Stone Canal, (1996) blue goo is a generic anti-nanomachine antiseptic.

In Iain M. Banks's "Culture" series, specifically in Excession, (1996) the major possible threat to the Culture is considered to be something called an "Aggressive Hegemonizing Swarm", selfish self-replicating devices intent on turning all matter in the Universe into copies of themselves.

In Stephen Baxter's Moonseed, (1998) Venus and the entire earth are engulfed by grey goo forcing the inhabitants of earth to flee to the moon, which is immune to the goo because of an alien presence.

Wil McCarthy's science fiction novel Bloom (1999) is set in a future in which a grey goo has overwhelmed the entire inner solar system, with the only remaining colonies of humans surviving in the asteroid belt and on Jupiter's moons.

In Yukito Kishiro's Battle Angel Alita: Last Order (2000-), gray goo is mentioned by a Venusian councilor during a LADDER meeting. Apparently the result of bored teenagers messing with common nanotechnology, it is the reason LADDER has made very strict laws concerning the use of nanotech in the solar system.

James Alan Gardner includes a grey goo incident in his sci-fi novel Ascending (2001). A spy on a starship intentionally causes the incident using a computer-sabotaging nano agent.

In Jasper Fforde's Thursday Next novel Lost in a Good Book (2002), the entire world is (and later is not) turned into a sweet-tasting pink goo by nanomachines designed to manufacture strawberry Dream Topping.

Patrick Larkin's contribution to the Robert Ludlum Covert-One series, called The Lazarus Vendetta (2003), is about nanotechnology initially derived for benevolent purposes but intentionally set loose by terrorists on the public using biological signals. Victims are turned into "organic soup" as the book states; piles of goo and bone fragments.

Alastair Reynolds' book "Century Rain" (2004) describes an Earth decimated by an eruption of nanotechnology (an event referred to as the "Nanocaust"). Although not a strictly traditional "grey-goo" scenario, it is still an outline of an apocalypse arising from uncontrolled nanomachinery.

Kurt Vonnegut's Ice-nine from the novel Cat's Cradle has similar properties to grey goo and is capable of "freezing" liquid water instantly if it touches it. It was accidentally dropped into the ocean and caused all the world's water to crystallize. It was in essence, a Doomsday device.

In television

In the science fiction television series Lexx, self-replicating robot arms called Mantrid drones wind up consuming the mass of an entire universe. Mantrid drones were macroscopic machines, but they apparently used nanotechnology as part of their means of manufacturing new parts for themselves.

Stargate SG-1 also fought a form of macroscopic self replicating machines. This enemy was known as the Replicators. The basic building block of the Replicators is a 1cm trapezoidal block containing its own power supply and computing/memory capacity. These blocks could be then organized into structures as simple as six-legged arachnoid scout bot to faster-than-light capable star ships of unlimited size. The first replicators were built by a defective android, but due to their immense computing power and hive mind, they quickly became sentient and began executing their own agenda of converting the entire universe into replicators. The initial replicators were macroscopic, but more advanced nanoscopic versions appeared that could mimic humanoid lifeforms.

Enterprise has an episode entitled "Vox Sola" in which the Enterprise is being overtaken by a biological entity. A strange, symbiotic alien creature boards Enterprise and captures several crew members and Hoshi has to decipher the creature's complex language. On the entity's planet, T'Pol, Reed, Phlox and Hoshi land in a shuttlepod and release the entity at the coordinates given earlier. Phlox also releases the tendril severed in the Cargo Bay, which is reabsorbed. As the shuttlepod returns to the Enterprise, dawn breaks and the area is revealed to be covered with one huge grey organism. Granted this "organism" would be labeled "green goo" due to being biological and not a nanotechnological (mechanical) entity, but the entity is related to grey goo due to appearance and hyper-assimilation actions.

In Babylon 5's spin-off Crusade, a race called the Drakh have released a nanovirus plague on Earth, which will destroy all life on Earth within five years if it is not stopped.

An episode of Cartoon Network's series Justice League Unlimited entitled "Heart of Darkness" pitted the comic book heroes of the DC comics universe against a nanotechnological weapon of mass destruction created by an ancient alien race designed to defeat its enemy by literally devouring the planet from under them. It is stopped when The Atom is sent inside the central mass to examine and attack it at the source.

One fanciful depiction of a grey goo crisis was in an episode of the Gargoyles animated series where the protagonists face an advanced form of nanotechnology. They eventually manage to convince it to stop its spread.

The computer-animated cartoon series ReBoot featured a computer virus called 'Medusa' that was stolen by Megabyte from Hexadecimal and accidentally unleashed, speading in a manner similar to grey goo, turning everyone and everything in mainframe save for Bob and Hexadecimal to stone. Bob then confronts Hexadecimal and convinces her to release the antivirus, returning mainframe and it's inhabitants to normal.

Another cartoon version of "grey goo" is seen in an episode of A Real American Hero titled The Germ, in which an experimental pathogen dubbed "Bacteria X" is stolen by Crimson Guard agents who double-cross Destro. In typical Cobra fashion, the vial is clumsily dropped along with a growth formula that Destro was developing, and the combination transforms into a giant blob that consumes everything in its path. The Joes throw everything at it from missiles to insecticide — to little effect — and even send Airtight into the blob with an explosive dose of antibiotics, but the attack only prompts the blob to divide into two. When one blob is weakened after devouring a path through an apple orchard, the Joes figure its disagreeable reaction is caused by traces of poison, actually cyanide, in the apple seeds, so they bombard the blob with apples to destroy it.

In other media

In the virtual world Second Life, it is a popular term referring to player-coded objects that self-replicate out of control and thus (intentionally or otherwise) consume server resources and end up as a Denial of Service attack.

Sierra Entertainment's computer game Outpost 2 was a Civilization-like game which theme was based on a space colony where a lab exploded, creating a plague that consumed everything in its path, called 'the Blight'. As a side effect, the entire planet was transformed into a huge computer.

Sid Meier's Alpha Centauri the unofficial sequel to Civilization 2 had one "Secret project" called the Nano-factory. When built, units can be repaired in the field, even in enemy territory. The premise was of a nanomachine fluid that can absorb and reprocess any items to which it is exposed and use that raw material to produce weapons and equipment. "Industrial Grade Nano-Paste, Planet's most valuable commodity, can also be one of its most dangerous. Simply pour out several canisters, slide in a programming transponder, and step well away while the stuff cooks. In under an hour the nano will use available materials to assemble a small factory, a hovertank, or enough impact rifles to equip a regiment. -Col. Corazon Santiago, 'Planet: A Survivalist's Guide'"

Also in Alpha Centauri was a colony upgrade called a Nanoreplicator, which ostensibly used nanomachines to perfectly replicate any item down to the atomic level.

In the introduction sequence of Ion Storm's futuristic PC and Xbox game Invisible War, a nanotechnology bomb called a nanite detonator is detonated by a terrorist cell to destroy the city of Chicago. The result of the bomb being detonated is a wave of grey goo that consumes and destroys the entire city.

Activision's computer strategy game Call to Power contained a military unit called the 'Eco Ranger', which could be used under an 'Ecotopian' government to completely destroy a city and its surroundings, almost like a nuclear weapon. Unlike a nuclear weapon, which halved a city population, destroyed all military units and tile improvements around the city as well as polluting several adjacent tiles, this unit was supposed to use nanomachines, 'grey goo', to completely destroy the city and its surroundings, converting the area into pristine wilderness.

The Zerg in Blizzard Entertainment's StarCraft series have a structure called a Creep Colony, it is a building sized organ that produces "Creep". Creep is a layer of purple tissue that all Zerg buildings are built on. It functions as connective, circulatory and nervous tissue tying all the structures into one organism.

On Mr. Bungle's 1999 album California the song 'None of Them Knew They Were Robots' contains the lyrics- 'I feel the Grey Goo boiling in my blood'.

The Konami game Nanobreaker has an opening sequence in which nanomachines reduce all the living organisms on an island to grey goo.

References

Lynn Margulis and Doris Sagan - What is Life? (1995). Simon & Schuster. ISBN 0-684-81087-5
Bill Bryson A Short History of Nearly Everything (2003)
Green Goo: Nanotechnology Comes Alive!
Green Goo: The New Nanothreat from Wired

External links

Nanotechnology | Artificial life | Environmental disasters | Armageddon

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