A reader asks a general question about mechanosynthesis — How could a device release a reactive molecule once it’s bound to a product? — and I’d like to outline why there are many answers.
Mechanosynthesis is a very broad concept, and describes the operational principle of mechanisms that range from ribosomes in cells to rotary devices in prospective high-throughput atomically precise manufacturing systems (about which, see: physical basis, National Research Council assessment [pdf], technology roadmap)
The answer therefore depends on the application, and the right place to look for answers is usually in existing chemistry, with occasional excursions into density functional theory.
For example, there are many chemical reactions that transfer one or a small group of atoms from one covalent structure to another, and some of these reactions can be useful in mechanosynthetic contexts (SN2 reactions, acyl transfer, and hydrogen abstraction, among others).
Another strategy is to transfer a reactive molecule as a whole, using relatively weak binding interactions to fix it to a device while it is positioned to form strong, covalent bonds to the product structure. There is, of course, an enormous literature on noncovalent binding interactions.
To think productively about this question in a general and relatively comprehensive way requires an understanding of the fundamental principlea of a range of non-covalent interactions, of transition state theory and statistical mechanics, of covalent bonding and the challenges of organic synthesis, and of a range of methods and phenomena described in specialized literatures in several fields of chemistry and materials science.
Fortunately, the areas of greatest current interest today are largely outgrowths of molecular biology and supramolecular chemistry. These are areas where there are many competent researchers and established techniques. The great need today is to organize this knowledge around problems of designing and building next-generation macromolecular systems, exploiting self-assembly.
It’s important to remember that there’s no sharp line between self-assembly and mechanosynthesis.
{ 8 comments… read them below or add one }
Drexler
I wonder, to accelerate molecular nanotechnology
How much money would be needed to accomplish in a few years this wonderful technology?
thanks
I’d phrase the question differently, in terms of a series of stages of development along a broad, evolutionary pathway. As I’ve said above and elsewhere, there’s a continuum of technologies, and no sharp threshold.
A better focused effort could greatly accelerate progress in strategic directions while only moderately expanding current research programs in nanotechnology and the molecular sciences: The key is to organize a greater portion of the research around specific objectives and coherent sets of enabling technologies for next-generation molecular systems engineering. The pieces are mostly there already, because progress in the required science has been enormous.
This shift in the applications and directions of current research is, I think, inevitable. It will accelerate the development of a new engineering discipline and accelerate understanding of both incremental and longer-term opportunities. I am persuaded that this understanding will lead naturally to a more substantial shift in funding priorities.
I understand there is a linear and exponential technology, nanotechnology Foje not the rule, the research allows a concomitant exponential, however Drexler, for incredible as it seems, by private interests, they may hinder any technology, at least in the medium term, I will explain.
We have an air-powered cars, electric and hydrogen, but still drive cars that use fossil fuels or biofuels, other energy sources are abundant, and because they are not scarce, are not privatize, so there is no profit, although extremely efficient, clean and cheap, perfect for “saving the planet from environmental disaster facing us”, yet they invest billions, trillions in petroleum, two thirds of petroleum is used for the cars, too much for the other sectors that can easily be replaced by biotechnology. This is just one example of millions that could be mentioned.
I believe that researchers in molecular nanotechnology, get support from environmentalists, progressive scientists, civil society and interested in social and scientific progress.
what do you think?
Steve, I agree that the civil society groups you mention have good reason to support (and help influence) emerging molecular nanotechnologies, for a host of obvious reasons.
I also agree that private interests can take steps to hinder the development — and even more so, the deployment — of competing technologies, particularly when they are enmeshed in a political/regulatory system. It’s been suggested that fossil fuel companies may, for example, have helped to boost anti-nuclear sentiment, raising it above the level it would otherwise have reached.
However, I don’t find the examples of compressed-air, electric, and hydrogen vehicles to be persuasive. Each of these faces severe technological constraints despite unfettered research and development — even deployment — world wide. Relative to hydrocarbon fuels, each has problems with energy density and storage, various combinations of disadvantages in cost, weight, safety, and availability.
Electric vehicles, of course, have already gained a position in the market, and have scope for considerable technological improvement. Compressed air has less scope for improvement, and a very inferior energy storage density.
Hydrogen is an odd case, with so many problems that Steve Chu tried to drop funding. I suspect that much of the appeal of a “hydrogen economy” (to the public, at least) stems from the ignorant idea that hydrogen is a source of energy — magically made abundant because water is abundant — rather than being what it is: a way to store energy from other sources, someday, but today, a a fossil-fuel derivative.
exactly, you’re right
For example, as you know, solar energy inexhaustible energy source, one hour that focuses on the land, the amounts we produce for one year with conventional methods, of course you’re the expert, knows that nanotechnology, nanotechnologies are enabling up to 70% conversion into electrical energy, which overcomes the obsolescence of the silicon wafer that converts 10 percent, there is a company in California that produces these panels every 10 seconds, thin and efficient, do not know if they are with 70% efficiency.
but, I believe that in the case of molecular manufacturing, the problem would not be “competing technology”, competitive technologies because they just transfer the capital to another owner or corporate group, may cause technological unemployment and concentrate capital, but still works the other productive sectors of the economy.
Well we are in an open society, democratic and allowing freedom of expression, so I’ll mention, which in my view, this inhibiting the full development of molecular nanotechnology, and why investing in nanotechnology incremental claim that there is not feasible “technically or economically “, But it is not.
First the economy has a few categories:
* Private ownership of means of production
* Terms of trade (market)
* Profit
* Division of labor
* Wage labor
* Supply chains
Being brief, the only factor-of-production (raw, force-of-work, machinery and buildings, technology) that energizes the economy is the labor force, which receives a fee, salary and consume products and services, and much of the population are employed
That is, molecular nanotechnology abolishes the need for manual labor, so the employees, abolishes the division of labor, so you need not money, since she emerged as the unit of trade for products and services produced by the division of labor, as is a technology that allows you to expand the means of production, cost practically nil, so it is called exponential manufacturing, civil society, all social actors may be the owner of the means of production, so the profit is also abolished, and how it is produced using abundant raw material such as acetylene or propane, you do not need extensive supply chains and division between these production units
Drexler In short, this is why they do not want to molecular nanotechnology, and not “danger” of war, or because Grey Goo, or any other factor
The strategy is to try to ridicule the technology, saying it is “fiction” or that there is an impossibility for fat finger, and nonsense.
You have to go ahead, because it depended on a minority, we would be in believing in Feudalism, Geocentrism, Creationism and so on.
And we’re here to help you, civil society, environmentalists, scientists, progress will come sooner or later.
Hmmm… The situation I see looks rather more mundane, with plenty of confusion, but not much actual conflict.
As I’ve said, there’s been ample progress on science needed for a more systematic approach to macromolecular systems engineering. The weakness is on the engineering side, and it results chiefly from the lack of the right kind of engineering tradition in the molecular sciences. Without this, it’s hard for people to ask the right questions, hence the confusion about the answers.
I understand
I will ask some questions about the nanofactories
1 -) The raw material to be used, must necessarily be in a gaseous molecules because they are more “free”?
2 -) The propane and acetylene are obtained from natural gas, derived from non-renewable oil and thus could not use ethanol, for example, since the boiling point is at 73 degrees? And what other substances we could use as raw material, easy to be obtained in nature and abundant?
3 -) How to make a car with a nanofactories? Each nanofactory produce a part of the car and working in unison or would have a production process that integrates system engineering today as robotic arms and macroscopic with nanofactories?
4 -) Is it possible to increase the dimensions of a nanofactories? For example building a nanofactories the size of a bus to produce vehicles of all types?
These questions make me uneasy Dr Drexler, i´d like to know
Thank you very much
Your questions are basically about input materials and the scale of output products for advanced APM systems.
The choice of input materials is only weakly constrained. Think of the range of simple feedstock chemicals that can be used as a starting point for making the reactants used in organic synthesis.
Regarding the size of products, there’s not necessarily anything special here, either, because assembling macroscopic parts to make larger products (such as cars) is a familiar problem with familiar solutions. There’s a lot that could be said about facility size, machine specialization, etc., but these engineering questions are only loosely related to question of how the parts themselves are made.