Nanotechnology - Board 2

Posted by Royal Academy of Engineering
Media coverage of nanotechnologies has invariably raised the spectre of the ‘grey goo’: a doomsday scenario in which nanoscale robots self-replicate out of control, producing unlimited copies of themselves, consuming all available material and ultimately laying waste to the planet. Whereas most of the scientific community considers this to be science fiction, others have argued that it is a possible outcome of unregulated nanotechnology. The level of public and media interest in nanotechnology therefore justifies the following question: Is ‘grey goo’ a real concern, or is it a distraction from the important issues?

The original concept of molecular manufacturing described by Dr Eric Drexler, Chairman of the Foresight Institute, imagined the synthesis of materials and objects by a mechanical ‘assembler’; that is, a machine with the ability make any object by selecting atoms from the environment and positioning them, one at a time, to assemble the object. This assembler can be programmed and is independently powered. As it can make any object, it can reproduce itself. If the process malfunctions or is corrupted, intentionally or not, the self-replication process could continue indefinitely. Over the past 20 years or so, Drexler and his colleagues have continued theoretical studies of the feasibility of such machines, but as far as we are aware there is no research in this field that has been supported by funding agencies, and there has been no practical experimental progress over this period. The reason is simple: there are many serious fundamental scientific difficulties and objections, to the extent that most of the scientific community believes the mechanical self-replicating nano-robot proposal to be impossible.

The scientific issues have been debated in open correspondence between Dr Drexler and Professor Rick Smalley, co-recipient of the Nobel Prize for Chemistry in 1996 for the discovery of carbon 60—so called buckyballs. In summary, there are two major difficulties: first, to lift and position atoms one needs very fine manipulators, of a similar size to the atoms being worked with; second, the atoms being manipulated must first attach – i.e. chemically bind – to the manipulator, and then unbind from the manipulator and bind to the object. Although scientists have used atomic force microscopes to manipulate a restricted group of individual atoms and molecules into simple structures on surfaces, the properties of matter on this lengthscale appear to be incompatible with the requirements for a mechanical self-replicating technology. These objections have been termed by Smalley as ‘thick fingers’ and ‘sticky fingers’. Professor George Whitesides has questioned the feasibility of the energy management system that would be needed to handle the large energy input and release that occurs at the different stages of the construction process. Because the assembler is a nanomachine, its positioning accuracy is severely limited by the intense bombardment it receives from atoms in the environment – whether gaseous or liquid – which causes Brownian motion. It is quite clear: making a mechanical self-assembler is well beyond the current state of knowledge.

Our experience with chemistry and physics teaches us that we do not have any idea how to make an autonomous self-replicating mechanical machine at any scale, let alone nanoscale. Where we can find self-replicating machines is in the world of biology. The cell, thousands of nm in size, is the smallest unit we know that contains all the machinery essential for the process of reproduction, given a suitable environment. In fact, the planet we know today is quite different from its earliest form: biology evolved and turned a desert into the ecosystem of which we are now a part. At present however, the complete details of operation of even a simple cell are far beyond our understanding.

Given the above, we have heard no evidence to suggest that mechanical self-replicating nanomachines will be developed in the foreseeable future, and so would direct regulators at more pressing concerns outlined in chapter 8.

Re: the topic at hand, nanotechnology is pretty cool and awesome, and it's nice how much it's come into our daily life. But what is mentioned in the article linked from 2010 on is pretty well not possible. Nice as it is, it just can't self-replicate.

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