Assembler (nanotechnology)

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In molecular nanotechnology , an assembler (also known as a molecular assembler) is a hypothetical robot in miniature format ( nanobot ) that manipulates individual atoms and molecules . This could be used to create molecular structures that do not occur in nature. The first sketch of such a device comes from Eric Drexler in 1986, in his book Engines of Creation , in which assembler is presented as the basis of molecular nanotechnology.

One of the longer-term goals of nanotechnology is / was the production of programmable , self-replicating assemblers. For some time, however, the focus has shifted to nanofactories as an alternative access to diamond-like productive nanosystems. An assembler can produce complete copies of himself with the correct construction plans and with the appropriate supply of raw materials and energy. When these copies have made more and the number has grown exponentially over time , they are reprogrammed to make another product.

A contemplated assembler design would contain about 1 billion atoms and place about 1 million atoms per second, giving a replication time of 1,000 seconds, or just over 16 minutes. It follows that 1 kilogram of assemblers could also produce 1 kilogram of another product within approx. 16 minutes.

The preferred material for an assembler (and nanofactory too) is carbon in its diamond form, as it is stiff enough to sufficiently suppress the amplitude of the thermal vibrations so that robotic manipulators can create individual chemical bonds with extremely low probability of error (similar to digital logic ) in the right place. In addition, diamond has outstanding material properties and is chemically extremely inert with a hydrogen passivation (very remotely similar to flour on the dough, which prevents sticking together) . These properties carry over to most of the products that assemblers (or nanofactories) could make.

Demarcation

Assemblers should not be confused with nano robots / nano devices which in principle do not need the ability to self-replicate and also have completely different design criteria. This includes, for example, medical nanorobots , utility fog nanorobots and various other nano devices.

Assembler vs nanoproductions

Assemblers have long been considered by experts (including Eric Drexler and Chris Phoenix, Ralph Merkle and Robert Freitas) to be neither practical nor desirable, but not fundamentally impossible. Instead, diamond-like nanofactories are currently being targeted as a sensible long-term goal ( mechanosynthesis ).

On the practicality of assemblers

There are arguments that assemblers have poorer technological accessibility and poorer production efficiency than nanofactories.

  • Inferior technological accessibility: To directly build a diamond-like assembler, a very large technological leap is necessary, while the way to diamond-like nanofactories can take place gradually via more primitive “productive nanosystems”. The more difficult direct access to assemblers requires the construction, atom by atom, of a fully replicable “proto-assembler” using the needle tip of an AFM / STM microscope. The simpler step-by-step access to “diamond-like nanofactories” could begin with breadboard-like systems from “structural DNA nanotechnology” via systems from minerals that can be synthesized in water to nanofactories made of diamond and similar precious stones in a vacuum.
  • Inferior production efficiency: assemblers are not specialized in standard components (bearings, gears, connectors, wedges ...) and are therefore fundamentally inferior to nanofactories in terms of spatial and temporal production density.

On the desirability of assemblers

Self-replicating assemblers are often associated with the "gray-goo" problem. Even if many SciFi representations of an uncontrolled outbreak are far exaggerated (assemblers are not mutating omnivores), it is probably not desirable to actively strive for assembler, especially if the nano factories are an easier to achieve, more efficient and safer alternative.

Self-replication vs exponential assembly

Self-replicating autonomous units are not an indispensable necessity for the production of macroscopic (e.g. fist-sized) atomically precise goods. The strong media presence of this outdated idea has meant that, besides “gray-goo”, other dangers arising from molecular nanotechnology, which have the same, if not even greater damage potential, received less attention.

In contrast to assemblers, the gradual path to nanofactories avoids the self-replication of compact autonomous units. So-called “exponential assembly” (not to be confused with “convergent assembly” - another concept of nanofactories) can be used once during development to exponentially multiply a single core (e.g. a trivial linkage mechanism). This could lead to a “proto-nanofactory”. Instead of individual groups of atoms, prefabricated, atomically precise components are put together by means of “self-assembly”. In no step of their entire development phase are nanofactories neither as extremely compact nor as potentially mobile as assembler. Therefore, an unintentional "gray-goo accident" of self-replicating nanofactories is practically impossible in the development phase.

Skepticism towards assemblers

While some scientists see these robots as one of the most important future technologies , others deny that such a technology can be made at all. The faction of skeptics has shrunk in recent years, also given the growing body of contradicting evidence.

Other concerns arise from the nature of the assembler. In a scenario in which they have their own blueprints "on board" and are able to replicate themselves, assemblers that have gone out of control destroy the entire biosphere in order to gain energy and raw materials for their self-replication. This scenario is referred to as the “ gray goo scenario ”, since large parts of the biomass are transformed into “ gray goo ”. The problem can be avoided by outsourcing the construction description, since assemblers then have to access a central construction plan instead of containing it themselves and in the event of an escalation the self-replication can be stopped.

However, the conditions that would have to be met for the “gray smear scenario” show that this risk is less serious than that which otherwise arises through molecular nanotechnology .

A completely autonomous, self-replicating assembler would not only be more difficult to develop and less efficient than a specialized one, but also, as a direct consequence, would be less economically interesting. This is not to say that it is physically impossible, just that there is less incentive to develop such an assembler.

The construction of a so-called “protoassembler”, which acts as the starting device, means a great deal of effort, since thousands and thousands of atoms would have to be joined together. One possible way to get there is through DNA construction.

Suspected cause of the straw man arguments

Eric Drexler explains in his popular science book Radical Abundance how, in his opinion, straw man criticism , discrediting, censorship and the cancellation of funds for relevant research came about.
Briefly and roughly chronologically:

  • Drexler published Engines of Creation (EoC), in it: nanotechnology, big promises, the assembler concept and the gray-goo problem.
  • Researchers (A, knowing) are starting to use the “nano” mark to get better research funding. Reason: big promises. However, there is little relevant research that targets atomically precise productive nanosystems. The meaning of the term “nanotechnology” is therefore beginning to expand considerably.
  • More and more researchers (B, ignorant) are using the “nano” brand, although they have never heard of EoC.
  • The public, sci-fi writers, and the media are taking in and puffing up the gray goo doomsday scenario as it sells well.
  • Experts have long shifted the focus from assemblers to nanofactories and have done a lot of theoretical work, which is illustrated, for example, in Drexler's technical book Nanosystems . This is hardly noticed by the media and the public.
  • “Nanotechnology” researchers (B) are overwhelmed by the media with expectations and, above all, fears based on assemblers who have absolutely nothing to do with their research.
  • Affected researchers (B) read, if at all, EoC instead of nanosystems -> outdated, incomplete ideas are naively completed by researchers (B) and rightly presented as a non-functioning phantasy.

Biological assembler

Bacteria and other unicellular organisms are nature's relatively small self-replicating assemblers that are programmed by genes . The biotechnology is concerned with the use of cells and their products in industrial applications and also includes the "reprogramming" of cells by transformation with foreign and modified genes. The result is genetically modified organisms and recombinant proteins . Methods like DNA origami can create DNA machines .

Web links

Individual evidence

  1. ↑ a b Chris Phoenix, Eric Drexler: Safe Exponential Manufacturing , 2004 (English).
  2. ↑ Ralph Merkle: The potential of the nanofactory. (No longer available online.) Archived from the original on August 1, 2017 ; accessed on September 1, 2017 (English).
  3. ↑ Ray Kurzweil and Robert Freitas discuss the future of nanotechnology. Retrieved September 1, 2017 (English).
  4. ^ Andreas Eschbach : The book of the future - A travel guide , page 48 f., ISBN 3-87134-476-1 .
  5. ^ Robert A. Freitas Jr., Ralph C. Merkle: Kinematic Self-Replicating Machines, 5.1.9.A Replication Control , 2004.