Grey goo

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Molecular assembler Mechanosynthesis Molecular machine Productive nanosystems Nanorobotics K. Eric Drexler Engines of Creation Grey goo

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Grey goo is a hypothetical end-of-the-world scenario 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 (eating the environment).

The term grey goo is usually used in a science fiction or popular-press context. In the worst postulated scenarios (requiring large, space-capable machines), matter beyond Earth would also 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). The disaster is posited to result from a deliberate doomsday device, or from an accidental mutation in a self-replicating nanomachine used for other purposes, but designed to operate in a natural environment.

Contents 1 Living goo 2 Risks and precautions 3 Famous quotes 4 Grey goo in science fiction 5 See also 6 References 7 Further reading 8 External links

[edit] 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.

The cell is the archetypal nanomachine and in fact does have many of the properties ascribed to grey goo, particularly, the ability to transform unstructured materials into copies of the replicating agent. Hence, the cell is able to incorporate carbon dioxide, molecular nitrogen gas, and water into complex, multifunctional biomolecules, as well as incorporating solid materials such as hydroxyapatite, and other calcium and phosphorus containing compounds. While certainly not the ecocatastrophe posited by grey goo alarmists, the transformative and contaminative nature of cells is impressive. Earth would certainly be a different place without the appearance of the cell (the most impressive of which would be the lack of an atmosphere containing large amounts of oxygen), and the possibility of seeding and contaminating the rest of the Solar System with cells is a real consideration when planning space missions.

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 only 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.^{[original research?]}

A more literal biological analogy to grey goo are prions, which have been implicated in such diseases as kuru, Mad Cow disease, Creutzfeldt-Jakob disease, and fatal familial insomnia. In all of these conditions, an abnormal protein possesses the ability to unfold and refold other normally functioning proteins into copies of itself. Prions are extraordinarily contagious and difficult to destroy, but their relatively sluggish rate of transformation has prevented them from successfully overrunning the biosphere.

[edit] 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 self-replicating machines 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, 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 (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 would decrypt to a meaningless, random bit string.

Drexler more recently conceded that there is no need to build anything that even resembles a potential runaway replicator. This would avoid the problem entirely. In a paper in the journal Nanotechnology, he argues that self-replicating machines are needlessly complex and inefficient. His 1992 technical book on advanced nanotechnologies Nanosystems: Molecular Machinery, Manufacturing, and Computation [1] describes manufacturing systems that are desktop-scale factories with specialized machines in fixed locations and conveyor belts to move parts from place to place. Popular culture, however, remains focused on imagined scenarios derived from his older ideas. None of these measures would prevent a party creating a weaponised grey goo, were such a thing possible.

Oxford based philosopher Nick Bostrom discusses the idea of a future powerful superintelligence, and the risks that we/it face should it attempt to gain atomic level control of matter.

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, and dismisses the idea as impossible.

More recent analysis has shown that the danger of grey goo is far less likely than originally thought.^[1] However, other long-term major risks to society and the environment from nanotechnology have been identified.^[2] 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.

[edit] 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

[edit] Grey goo in science fiction

• In Frank Herbert's Dune series, a weapon is being researched at one point which would be 'a self improving thing which would seek out life and reduce that life to its inorganic matter.' Though not nanotechnological in nature, the autonomous but unthinking threat is similar. ^[3]
• In Ray Kurzweil's film The Singularity Is Near, a computer avatar called Ramona discovers that some nanorobots could destroy the world if not stopped.
• In Wil McCarthy's sci-fi novel Bloom, Earth’s ecosystem is destroyed within hours by a grey goo, annihilating all biological life. The grey goo then develops its own unique “ecosystem”. The only human survivors are colonists who flee to the outer solar system. The book's protagonists come from Jupiter’s moon Ganymede.^[4]
• Although not strictly speaking science fiction, Jasper Fforde's Lost in a Good Book features a narrowly-averted apocalypse in which all biological life in the world is converted into "Dream Topping" (a whipped cream-like substance) by overenthusiastic nanomachines.
• In the intro to the video game Deus Ex: Invisible War, a villain uses a nanite detonator, wiping out the entire city of Chicago with a goo-like substance that seems to freeze/destabilize anything it comes into contact with.
• Self-reproducing nanorobots were heavily featured in Michael Crichton's novel Prey.
• In Greg Bear's novel Blood Music, simple biological computers evolve to become self-aware 'noocytes', which assimilate most of the biosphere of North America before abandoning the normal plane of existence.
• In Universe at War: Earth Assault, Novus uses a megaweapon called the grey mass launcher, which turns a territory in global mode into a "grey mass".
• Smoke's ending in Mortal Kombat Armageddon describes grey goo consuming the realm of Edenia.
• In Walter Jon Williams' novel Aristoi, Earth was destroyed by grey goo (codenamed "Mataglap") and it is used to destroy an asteroid installation owned by the protagonist.
• In the made-for-TV film Path of Destruction, accidentally released grey goo causes weather problems.
• In John Robert Marlow's novel Nano, the invention of self-replicating nanites results in a team of assassins hired by the government on the hunt for a scientist and reporter, nearly ending in the destruction of San Francisco by "incorrectly programmed" grey goo.
• In Gargoyles episode Walkabout, a sentient nanite swarm called "The Matrix" is confronted in the Australian outback.
• In the book Specials by Scott Westerfeld the characters Tally Youngblood and Shay use grey goo to break out of the armory in New Pretty Town.
• In Moonseed, the 1998 book by Stephen Baxter, the Earth is consumed by a grey goo-type substance inadvertantly imported from the Moon.
• In the game Supreme Commander by THQ and Gas-Powered Games, the Aeon Illuminate uses a grey goo material to construct all of their buildings and units. The commander shoots a puddle onto the ground and then it starts to rise and shape into the desired object.
• In the game Outpost 2, the faction of Eden is experimenting on a way to terraform the new planet they have settled to support life. Suddenly the experiment goes horribly wrong and a nanotechnology/terraforming virus is released, eventually taking over the planet and causing the survivors to work together in order to build a new spacecraft to leave the planet to find a new one.

[edit] See also

• Clanking replicator (often called von Neumann machine)
• Culture shock
• Ice-9
• Midas touch
• Precautionary principle
• Self-replicating spacecraft
• Technology assessment

[edit] References

[edit] Further reading

[edit] External links

• Some Limits to Global Ecophagy by Biovorous Nanoreplicators, with Public Policy Recommendations
• Nanotechnology pioneer slays “grey goo” myths Paper critical of "grey goo"
• Online edition of the Royal Society's report Nanoscience and nanotechnologies: opportunities and uncertainties
• Goo and Paste Directory
• UK Government & Royal Society commission on Nanotechnology and Nanoscience