Nanotechnology assemblers: likely or unlikely?

Nanotechnology assemblers: likely or unlikely?

The current issue of Nanotechnology Law and Business (Vol. 4, Issue 2) includes a surprising article called “Nanoassemblers: A Likely Threat?” by Martin Moskovits, a Professor of Chemistry and Biochemistry and Dean of the Division of Mathematical and Physical Sciences at the University of California Santa Barbara. I saw this just as I was heading out the door for a vacation, so have not had time to actually read it, but a quick skim is disappointing, e.g.:

To pick up a specific molecule from the environment and place it precisely where you want it, you would need “limbs” that are not very much bigger than a molecule. Such limbs are themselves composed of relatively few atoms or molecules. As a result the limbs are subject to thermal fluctuations, Brownian motion, and a quantum phenomenon called zero point motion. Thus, the nanobot’s limbs will jitter and their accuracy as an assembler will be faulty. A nanoassembler reaching for a given molecule will often miss, and because the jitter (both of the nanobot’s limbs and the molecule) is unpredictable, its reliability would be compromised.

It gets tedious reading analyses that present “thermal fluctuations, Brownian motion, and a quantum phenomenon called zero point motion” as possibly new information for those already in the discussion. This is like saying to the Wright Brothers: “Guys! What about gravity?”

I will have to leave a detailed critique of the article to others more able than I. But I can say one thing: I looked repeatedly and the book Nanosystems does not seem to be referenced. How could anyone write about this topic without citing and critiquing that book? It’s truly bizarre. Folks — is it there? I couldn’t find it. The author cites plenty of lighter material. What’s going on here?

One point you can see in the free abstract: “Simple, microscopic, self-replicating mechanical systems would also be possible, which could pose health and environmental threats not unlike pathogens…” The author is getting involved in the discussion of gray goo. He will probably regret that! —Christine

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One Comment

  1. Phillip Huggan June 26, 2007 at 11:00 am - Reply

    Diamond replicators would only function in substrates where there are a lot of carbon atoms. Effective seismic sensor grids and air filters might be possible before mature MNT could occur. With MNT, it will be far easier to deal with replicators than with faster-than-wind weaponry delivery systems.

    Thermal fluctuations will be dealt with as computer sim power improves. The critiques might or might not be true for materials with a Young’s Modulus lower than for diamond (a DFT sim would tell). I guess people are confusing the concept of a universal assembler with Mechanosynthesis. The latter might not prove powerful enough to revolutionize SPM manufacture, but Freitas et al’s simulations to date have proven that some deposition reactions would be successful despite…zero point energy.

    There is nothing specific in this critique; sophisticated critiques have been delivered in the past and responding to them requires a level of diamond surface chemistry knowledge that is beyond MNT proponents (and perhaps the state of the science too) at present. What are needed are a set of DFT mechanosynthesis sims garnered towards all the reactions necessary to construct a needed product. Say, an UHV filter or the ideal X-bar diamond tool-tip. If one needed product simply turns out to be un-MNTable and can’t be provided in sufficient quantities by some other chemical process, then the economic upside of MNT can be known and realistic “industrial scale-up” (as opposed to research) budget estimates can begin.

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