AstrochickenAstrochicken is the name given to a thought experiment expounded by theoretical physicist Freeman Dyson. An Astrochicken is a small, one-kilogram spacecraft, a self-replicating automaton that could explore space more efficiently than a crewed craft could due to its innovative mix of technology. In his book Disturbing the Universe (1979), Dyson contemplated how humanity could build a small, self-replicating automaton that could explore space more efficiently than a crewed craft could.
Gray gooGray 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 while building many more of themselves, a scenario that has been called ecophagy . The original idea assumed machines were designed to have this capability, while popularizations have assumed that machines might somehow gain this capability by accident.
Molecular machineMolecular machines are a class of molecules typically described as an assembly of a discrete number of molecular components intended to produce mechanical movements in response to specific stimuli, mimicking macromolecular devices such as switches and motors. Naturally occurring or biological molecular machines are responsible for vital living processes such as DNA replication and ATP synthesis. Kinesins and ribosomes are examples of molecular machines, and they often take the form of multi-protein complexes.
EcophagyEcophagy is a term coined by Robert Freitas that means the literal consumption of an ecosystem. It derives from the Greek "οἶκος" (oikos), which refers to a "house" or "household", and the Greek "φαγεῖν" (phagein), "to eat". Freitas used the term to describe a scenario involving molecular nanotechnology gone awry. In this situation (called the grey goo scenario) out-of-control self-replicating nanorobots consume entire ecosystems, resulting in global ecophagy.
Molecular assemblerA molecular assembler, as defined by K. Eric Drexler, is a "proposed device able to guide chemical reactions by positioning reactive molecules with atomic precision". A molecular assembler is a kind of molecular machine. Some biological molecules such as ribosomes fit this definition. This is because they receive instructions from messenger RNA and then assemble specific sequences of amino acids to construct protein molecules. However, the term "molecular assembler" usually refers to theoretical human-made devices.
Self-replicationSelf-replication is any behavior of a dynamical system that yields construction of an identical or similar copy of itself. Biological cells, given suitable environments, reproduce by cell division. During cell division, DNA is replicated and can be transmitted to offspring during reproduction. Biological viruses can replicate, but only by commandeering the reproductive machinery of cells through a process of infection. Harmful prion proteins can replicate by converting normal proteins into rogue forms.
Self-replicating spacecraftThe concept of self-replicating spacecraft, as envisioned by mathematician John von Neumann, has been described by futurists including physicist Michio Kaku and discussed across a wide breadth of hard science fiction novels and stories. Self-replicating probes are sometimes referred to as von Neumann probes. Self-replicating spacecraft would in some ways either mimic or echo the features of living organisms or viruses.
Self-reconfiguring modular robotModular self-reconfiguring robotic systems or self-reconfigurable modular robots are autonomous kinematic machines with variable morphology. Beyond conventional actuation, sensing and control typically found in fixed-morphology robots, self-reconfiguring robots are also able to deliberately change their own shape by rearranging the connectivity of their parts, in order to adapt to new circumstances, perform new tasks, or recover from damage.
Molecular nanotechnologyMolecular nanotechnology (MNT) is a technology based on the ability to build structures to complex, atomic specifications by means of mechanosynthesis. This is distinct from nanoscale materials. Based on Richard Feynman's vision of miniature factories using nanomachines to build complex products (including additional nanomachines), this advanced form of nanotechnology (or molecular manufacturing) would make use of positionally-controlled mechanosynthesis guided by molecular machine systems.
NanotechnologyNanotechnology, often shortened to nanotech, is the use of matter on atomic, molecular, and supramolecular scales for industrial purposes. The earliest, widespread description of nanotechnology referred to the particular technological goal of precisely manipulating atoms and molecules for fabrication of macroscale products, also now referred to as molecular nanotechnology. A more generalized description of nanotechnology was subsequently established by the National Nanotechnology Initiative, which defined nanotechnology as the manipulation of matter with at least one dimension sized from 1 to 100 nanometers (nm).
