Molecular nanotechnology

From Wikinfo

Molecular Nanotechnology (MNT) refers to exploratory engineering at the atomic and molecular level. Physically, molecular nanotechnology relates to sizes of only a few atoms' in dimension. Implementing nanotechnology in its fullest sense would require the ability to manipulate atoms or molecules with high control.

Advocates use a much more speculative term used to hype this field: "molecular engineering", generally by the use of mechanosynthesis. Progress towards actual engineering at these scales has proven very marginal at best. Speculations promise unheard of longer-term potential solving most of the problems we face nowadays, but often incorporate irrational assumptions: "If we could ... " (see below).

Ralph Merkle has compared today's chemistry (in contrast to mechanosynthesis) to an attempt to build interesting Lego brick constructions while wearing boxing gloves. Because we currently have no tools that allow us to place a particular molecule in a particular place (so that it bonds in a predictable way), we must work with randomly moving molecules. As a result, when we cause a particular chemical reaction, we frequently get a mix of several different product species. We must often follow up after the reaction with a physical filtering process to extract the species we actually wanted, with the other species discarded as waste. Nanotechnology could therefore offer much cleaner manufacturing processes than today's bulk technology offers.

Foresights

Hypothetical applications and capabilities

Smart Materials and Nanosensors

One application of nanotechnology is the development of so-called smart materials. This term refers to any sort of material designed and engineered at the nanometer scale to perform a specific task, and encompasses a wide variety of possible commercial applications. One example is materials designed to respond differently to various molecules; such a capability could lead, for example, to artificial drugs which would recognize and render inert specific viruses. Another is the idea of self-healing structures, which would repair small tears in a surface naturally in the same way as self-sealing tires or human skin; and while this technology is relatively new, it is already seeing commercial application in various engineering plastics.

A nanosensor would resemble a smart material, involving a small component within a larger machine that would react to its environment and change in some fundamental, intentional way. As a very simple example: a photosensor could passively measure the incident light and discharge its absorbed energy as electricity when the light passes above or below a specified threshold, sending a signal to a larger machine. Such a sensor would cost less and use less power than a conventional sensor, and yet function usefully in all the same applications � for example, turning on parking lot lights when it gets dark.

While smart materials and nanosensors both exemplify useful applications of nanotechnology, they pale in comparison with the complexity of the technology most popularly associated with the term: the nanobot.

"Nanobots"

In the fourth chapter of Engines of Creation, Drexler introduces the idea of self-replication (see also Von Neumann machine), another powerful premise of nanotechnology. Cells build copies of themselves in order to reproduce, and human-designed molecular robots could do the same thing. If a molecular robot could construct copies of itself from basic raw materials (most likely primarily carbon), once the first such robot was constructed any desired quantity could be obtained quite quickly and at very low cost. (Self replication is, of course, not the only way in which machines can build more machines.)

These same generally-capable robots, called assemblers, could then build more special-purpose objects that humans would find directly useful: houses, kitchen widgets, cars, furniture, medical instruments, spaceships, etc. Like the assemblers themselves, these products would cost considerably less than those produced today. Specifically, any such manufacturing process would have as inputs raw materials, energy, design software, and time. For less speculative discussion of this potential, see the separate article on the molecular assembler.

Another proposed application of nanotechnology involves utility fog [1] � in which a cloud of networked microscopic robots (simpler than assemblers) changes its shape and properties to form macroscopic objects and tools in accordance with software commands. Rather than modify the current practices of consuming material goods in different forms, utility fog would simply replace most physical objects.

However, critics doubt the feasibility of controllable self-replicating nanobots: they cite the possibility of mutations removing any control and favouring reproduction of mutant pathogenic variations. Advocates counter that bacteria mutate by design, and nanobot mutation can be prevented by common error-correcting techniques used in computers today. They also note that self-replicating machines do not form a necessary part of a productive nanotechnology. Research in this area has included the development of simulation software, such as NanoCAD.

Hypothetical social impacts

Despite the current early developmental status of nanotechnology, much speculation has occurred on its impact on economics and on law. Some imagine that the need for money would disappear and that the feasibility of taxation would vanish. Others conjecture that nanotechnology would elicit a strong public-opinion backlash, as has occurred recently around genetically modified plants and the prospect of human cloning. Whatever the exact effects, nanotechnology would probably upset existing economic structures, as it should reduce the scarcity of manufactured goods and make many more goods (such as food and health aids) manufacturable.

Most futurists and all economists believe that future citizens of a nanotechnological society would still need money, in the form of unforgeable digital cash. They might use such money to buy goods and services that are unique, or limited within the solar system. These might include: matter, energy, information, real estate, design services, entertainment services, legal services, fame, political power, or the attention of other people to your political/religious/philosophical message. Furthermore, futurists must consider war, even between prosperous states, and non-economic goals.

Most people believe that virtual reality will not much reduce interest in obtaining limited resources, such as a chance to talk to the real president of a major country, or owning part of the real Jerusalem, or having a famous celebrity say nice things about you in a digitally-signed document, or gaining the mining rights to the larger near-earth asteroids. Demand will always exceed supply for some things, and a political economy will continue to exist in any case.

Risks

Beyond the fantasy scenarios, nanotechnology has daunting risks. It enables cheaper and more destructive conventional weapons. Also, nanotechnology permits weapons of mass destruction that self-replicate, as viruses and cancer cells do when attacking the human body. Commentators generally agree that humankind should permit self-replication only under very controlled conditions, if at all.

A fear exists that nanomechanical robots (nanobots), if designed to self-replicate using naturally occurring materials (a difficult task), could consume the entire planet in their hunger for raw materials, or simply crowd out natural life, out-competing it for energy (as happened historically when blue-green algae appeared and outcompeted earlier life forms). Some commentators sometimes refer to this situation as the "grey goo" or "ecophagy" scenario. K. Eric Drexler considers an accidental "grey goo" scenario extremely unlikely. The "grey goo" scenario begs the Tree Sap Answer: what chances exist that one's car could spontaneously mutate into a wild car, run off-road and live in the forest off tree sap?

In light of these dangers, the Foresight Institute (founded by K. Eric Drexler to prepare for the arrival of future technologies) has drafted a set of guidelines [2] for the ethical development of nanotechnology. These include the banning of self-replicating pseudo-organisms on the Earth's surface, at least, and possibly in other places.