Gray goo (also spelled as grey goo) is a hypothetical global catastrophic scenario involving molecular nanotechnology in which out-of-control self-replicating machines consume all biomass on

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's sur ...

while building many more of themselves, a scenario that has been called ''

ecophagy Ecophagy is a term coined by Robert Freitas that means the literal consumption of an ecosystem. It derives from the Greek "οἶκος" (), which refers to a "house" or "household", and the Greek "φαγεῖν" (), "to eat". Freitas used the te ...

'' (the literal consumption of the ecosystem). The original idea assumed machines were designed to have this capability, while popularizations have assumed that machines might somehow gain this capability by accident. Self-replicating machines of the macroscopic variety were originally described by mathematician

John von Neumann John von Neumann (; hu, Neumann János Lajos, ; December 28, 1903 – February 8, 1957) was a Hungarian-American mathematician, physicist, computer scientist, engineer and polymath. He was regarded as having perhaps the widest c ...

, and are sometimes referred to as von Neumann machines or clanking replicators. The term ''gray goo'' was coined by nanotechnology pioneer

K. Eric Drexler Kim Eric Drexler (born April 25, 1955) is an American engineer best known for studies of the potential of molecular nanotechnology (MNT), from the 1970s and 1980s. His 1991 doctoral thesis at Massachusetts Institute of Technology was revised and ...

in his 1986 book '' Engines of Creation''. In 2004, he stated "I wish I had never used the term 'gray goo'." ''Engines of Creation'' mentions "gray goo" as a thought experiment in two paragraphs and a note, while the popularized idea of gray goo was first publicized in a mass-circulation magazine, '' Omni'', in November 1986.

Definition

The term was first used by molecular nanotechnology pioneer

in ''Engines of Creation'' (1986). In Chapter 4, ''Engines Of Abundance'', Drexler illustrates both

exponential growth Exponential growth is a process that increases quantity over time. It occurs when the instantaneous rate of change (that is, the derivative) of a quantity with respect to time is proportional to the quantity itself. Described as a function, a ...

and inherent limits (not gray goo) by describing " dry"

nanomachines A molecular machine, nanite, or nanomachine is a molecular component that produces quasi-mechanical movements (output) in response to specific stimuli (input). In cellular biology, macromolecular machines frequently perform tasks essential for l ...

that can function only if given special

raw materials A raw material, also known as a feedstock, unprocessed material, or primary commodity, is a basic material that is used to produce goods, finished goods, energy, or intermediate materials that are feedstock for future finished products. As feeds ...

: According to Drexler, the term was popularized by an article in science fiction magazine ''Omni'', which also popularized the term "nanotechnology" in the same issue. Drexler says

arms control Arms control is a term for international restrictions upon the development, production, stockpiling, proliferation and usage of small arms, conventional weapons, and weapons of mass destruction. Arms control is typically exercised through the u ...

is a far greater issue than gray goo "nanobugs". Drexler describes gray goo in Chapter 11 of ''Engines of Creation'': Drexler notes that the geometric growth made possible by self-replication is inherently limited by the availability of suitable raw materials. Drexler used the term "gray goo" not to indicate color or texture, but to emphasize the difference between "superiority" in terms of human values and "superiority" in terms of competitive success:

Bill Joy William Nelson Joy (born November 8, 1954) is an American computer engineer and venture capitalist. He co-founded Sun Microsystems in 1982 along with Scott McNealy, Vinod Khosla, and Andy Bechtolsheim, and served as Chief Scientist and CTO at ...

, one of the founders of Sun Microsystems, discussed some of the problems with pursuing this technology in his now-famous 2000 article in ''

Wired ''Wired'' (stylized as ''WIRED'') is a monthly American magazine, published in print and online editions, that focuses on how emerging technologies affect culture, the economy, and politics. Owned by Condé Nast, it is headquartered in San ...

'' magazine, titled " Why The Future Doesn't Need Us". In direct response to Joy's concerns, the first quantitative technical analysis of the ecophagy scenario was published in 2000 by nanomedicine pioneer

Robert Freitas Robert A. Freitas Jr. (born 1952) is an American nanotechnologist. Career In 1974, Freitas earned a bachelor's degree in both physics and psychology from Harvey Mudd College, and in 1978, he received a Juris Doctor (J.D.) degree from Santa Clara ...

Risks and precautions

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 Nanotechnology, also shortened to nanotech, is the use of matter on an atomic, molecular, and supramolecular scale for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal ...

'', he argues that self-replicating machines are needlessly complex and inefficient. His 1992 technical book on advanced nanotechnologies '' Nanosystems: Molecular Machinery, Manufacturing, and Computation'' describes manufacturing systems that are desktop-scale factories with specialized machines in fixed locations and conveyor belts to move parts from place to place. None of these measures would prevent a party from creating a weaponized gray goo, were such a thing possible.

King Charles III Charles III (Charles Philip Arthur George; born 14 November 1948) is King of the United Kingdom and the 14 other Commonwealth realms. He was the longest-serving heir apparent and Prince of Wales and, at age 73, became the oldest person to a ...

(then

Prince of Wales Prince of Wales ( cy, Tywysog Cymru, ; la, Princeps Cambriae/Walliae) is a title traditionally given to the heir apparent to the English and later British throne. Prior to the conquest by Edward I in the 13th century, it was used by the rule ...

) called upon the British

Royal Society The Royal Society, formally The Royal Society of London for Improving Natural Knowledge, is a learned society and the United Kingdom's national academy of sciences. The society fulfils a number of roles: promoting science and its benefits, re ...

to investigate the "enormous environmental and social risks" of nanotechnology in a planned report, leading to much media commentary on gray goo. The Royal Society's report on nanoscience was released on 29 July 2004, and declared the possibility of self-replicating machines to lie too far in the future to be of concern to regulators. More recent analysis in the paper titled ''Safe Exponential Manufacturing'' from the

Institute of Physics The Institute of Physics (IOP) is a UK-based learned society and professional body that works to advance physics education, research and application. It was founded in 1874 and has a worldwide membership of over 20,000. The IOP is the Physic ...

(co-written by Chris Phoenix, Director of Research of the Center for Responsible Nanotechnology, and Eric Drexler), shows that the danger of gray 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 gray goo hypothesis, in an effort to focus the debate on more realistic threats associated with knowledge-enabled nanoterrorism and other misuses. In ''Safe Exponential Manufacturing'', which was published in a 2004 issue of ''Nanotechnology'', it was suggested that creating manufacturing systems with the ability to self-replicate by the use of their own energy sources would not be needed. The Foresight Institute also recommended embedding controls in the molecular machines. These controls would be able to prevent anyone from purposely abusing nanotechnology, and therefore avoid the gray goo scenario.

Ethics and chaos

Gray goo is a useful construct for considering low-probability, high-impact outcomes from emerging technologies. Thus, it is a useful tool in the

ethics of technology The ethics of technology is a sub-field of ethics addressing the ethical questions specific to the Technology Age, the transitional shift in society wherein personal computers and subsequent devices provide for the quick and easy transfer of info ...

. Daniel A. Vallero applied it as a worst-case scenario

thought experiment A thought experiment is a hypothetical situation in which a hypothesis, theory, or principle is laid out for the purpose of thinking through its consequences. History The ancient Greek ''deiknymi'' (), or thought experiment, "was the most anc ...

for technologists contemplating possible risks from advancing a technology. This requires that a

decision tree A decision tree is a decision support tool that uses a tree-like model of decisions and their possible consequences, including chance event outcomes, resource costs, and utility. It is one way to display an algorithm that only contains con ...

or event tree include even extremely low probability events if such events may have an extremely negative and irreversible consequence, i.e. application of the precautionary principle. Dianne Irving admonishes that "any error in science will have a rippling effect". Vallero adapted this reference to chaos theory to emerging technologies, wherein slight permutations of initial conditions can lead to unforeseen and profoundly negative downstream effects, for which the technologist and the new technology's proponents must be held accountable.

In fiction

References

External links

Some Limits to Global Ecophagy by Biovorous Nanoreplicators, with Public Policy Recommendations

Paper critical of "grey goo," summarized in articl

* ttps://web.archive.org/web/20160303180055/http://www.nanotec.org.uk/ UK Government & Royal Society commission on Nanotechnology and Nanoscience
Nanotechnology: Drexler and Smalley make the case for and against 'molecular assemblers'
( Richard Smalley argues that laws of chemistry imply it will be impossible to ever create "self-replicating nanobots" whose abilities to assemble molecules are significantly different than those of biological self-replicators. Some pro-nanobot responses to Smalley's argument can be found a
Debate About Assemblers — Smalley RebuttalThe Drexler-Smalley debate on molecular assembly
an

Nanotechnology and the Grey Goo Problem
''BBC'' {{Doomsday Artificial life Doomsday scenarios 1980s neologisms Nanotechnology Robotics concepts Self-replicating machines Thought experiments in ethics