Revision as of 11:34, 14 July 2018

APM in the near term and APM in the far term

Today and near term

Pick and place assembly of single atoms (or molecule fragments) is not at all a necessity for early forms of APM.
In fact pick and place assembly is not needed at all for early forms of APM. Assembly driven by the "vigorous" thermal motion at the nanoscale (slightly misleading tech-term: "self assembly") can do the job.

• This Thermally driven assembly is not present in macroscale manufacturing. Therefore it is not present in our (knowledge and) intuition (unless we study the nanoscale in detail). Advanced APM is sometimes claimed to be impossible due to the effects of thermal motion. Which is clearly wrong for all the points that have been pointed at (mechanosynthesis, friction, ...). What is the case is that some proponents of advanced APM may lack knowledge (and intuition) regarding thermal motion.
• Thermally driven assembly puts thing together in faulty configurations quite often (high error rates). But its just enough such that one can start climbing the "stiffness ladder" introducing more and more restrained and forced motion leading to advanced APM.

It may come somewhat unexpected but in early APM systems there is no need for the atoms to stay in place. No, that does not contradict the introduction earlier. The atoms still need to keep their nearest neighbors they are strongly bonded to. What needs to be preserved such that is counts as atomically precise (in the weak (topological) sense) is just "what links to what" (tech-term: "bond topology").

In the early atomically precise systems of today the atoms tend to be bonded together in polymer chains. The whole chains constantly deform since the (zig-zag going) bonds in these polymer chains can (and very much do) rotate and flex. Thereby atoms can be displaced much more than their own diameter. Polymer chains with (mutually puzzle piece like matching) "side groups" that cause these chains to fold up into compact lumps (such chains are called: "foldamers") restrict this unwanted freedom of motion far enough to give the folded lumps a (more or less) predictable shape. But the location of the individual atoms may (and usually will) still wiggle around way beyond the diameter of the individual atoms.

In some sense even chemistry (the deterministic parts of it) could be counted as the earliest form of APM. (This is very much excluding macromolecular polymer chemistry with statistical cross-linking.) Important to note is that a major aspect of APM is that it specifically focuses on scaling up APM capabilities to bigger sizes. Chemistry is on the very bottom and does not scale up well.

In advanced atomically precise systems the atomically precise lumps are no longer made from folded up chains. Instead of chains the chemical bonds form tight meshes. Tiny crystals with molecule character. This tight mesh of bonds prevents the bonds from rotating, excessive stretching and bending. It is stiff. Here the location of the individual atoms can finally be restrained below the diameter of the individual atoms. This is atomically precise (in the strong (positional) sense). It allows advanced force applying mechanosynthesis.

In summary: While APM systems must always be topologically precise positional precision is reserved for the more advanced forms of APM.

Towards the far term

There are two core ideas that determine what the R&D direction from early forms of APM to advanced forms of APM actually is. This wiki will refer to those two ideas with the shorthand "gem-gum". This shorthand has been chosen since:

• it is catchy, in other words easy to spell and remember.
  whereas "high throughput atomically precise manufacturing" and "atomically precise manufacturing level technology" are not.
  (Source of these rather long terms: "Radical Abundance")
• it is highly specific and thus hard to annex by other concepts. It very clearly points to the far term goal
  which "high throughput atomically precise manufacturing level technology" does not.

Gem

Core idea #1 Gem:
Short for high stiffness gemstone like compound.

Gradual increase of the stiffness of the materials we build with is the ultimate key to raise our level of control over matter (the key to advanced mechanosynthesis). The term "gem" (short for gemstone - obviously) points exclusively to the ideal stiff base materials of the far term target technology. This explicitly excludes early stage atomically precise manufacturing such as "structural DNA nanotechnology"

Gem-Gum

Gemstone based mechanical metamaterials (here called "gem-gum") are a clear (and relatively simple) far term goal of APM. "Gem-gum" will extend the material properties that are available to us today to material properties that currently are deemed exotic or even contradictory and seemingly impossible. In the process of getting towards the far term goal of "gem-gum" even further reaching capabilities are likely to become accessible that can provide material properties even beyond those that "gem-gum" can provide. One of example would be: Direct mechanosynthesis of digestible food molecules. But these materials are even further out and even harder to predict.

Core idea #2 Gem-Gum:
Short for gemstone based mechanical metamaterials with seemingly contradicting and impossible properties. "Gum" (in the sense of rubber like stuff) made out of gemstone, is just a catchy example.

Even when one can mechanosynthesize almost nothing (just a few simple base materials) one can make almost anything by mechanical emulation. This is the "magic" of mechanical metamaterials. "Gum" is just a shorthand for one concrete example of such a metamaterial that rhymes on "Gem" which makes memorization a lot easier. Also it's a concrete example that's rather un-intuitive. Rubber made from gemstone. This could peak interest (click-bait effect).

Even with very minimal high stiffness nano-manufacturing capabilities (just one single high performance compound like e.g. diamond and nothing else) the amount of materials creatable will far exceed what is available today.

Limits to the ambitions

APM is sometimes said to have the goal to:

• Create most arrangements (or patterns) of atoms that are permitted by and consistent with physical law.

But that is even beyond the far term goal of gem-gum factories.

Due to the strong "pessimism" (more formally "conservativeness") of exploratory engineering the reliably predictable part of future tecnology is just the innermost naked core of what will really emerge. Part of this "innermost naked core" are just a few base materials. But these few alone are, when made into (mechanical) metamaterials, already sufficient for the emulation of an overwhelming plethora of material properties that goes far beyond what we have today (2017).

Much of the yet to come stuff that cannot yet be expected from the incremental path (including fundamentally unpredictable scientific discoveries) may remain in the final systems. But there also often will be strong reasons to ditch earlier legacy technology to not unnecessarily limit the range of situations in which the advanced products will be usable in.