Archive for December, 2004

Molecular nanotechnology, Drexler and Nanosystems – where I stand

Tuesday, December 28th, 2004

For the convenience of new readers of Soft Machines, here’s a quick summary of my personal positions on the question of the feasibility of the variety of nanotechnology proposed by Dr K. Eric Drexler in his book Nanosystems. Many of the arguments are made in my book Soft Machines; I’ve discussed some of these issues in my blog in the last few months, and I’ll get round to going into more detail about some of the others in the New Year.

  • Will it be possible to make functional machines and devices that operate on the level of single molecules?
    Yes. As pointed out by Drexler in his 1986 book Engines of Creation, Nature, in cell biology, gives us many examples of sophisticated machines that operate on the nanoscale to synthesise new molecules with great precision, to process information and to convert energy. We know, therefore, that radical nanotechnology (using this term to distinguish these sorts of fully functional nanoscale devices and machines from the sorts of incremental nanotechnology involved in making nanostructured materials) is possible in principle; the question is how to do it in practise.
  • Do the proposals set out in Drexler’s book Nanosystems offer the only way to achieve such a radical nanotechnology?
    Obviously not, since cell biology constitutes one radical nanotechnology that is quite different in its design principles to the scaled-down mechanical engineering that underlies Drexler’s vision of “molecular nanotechnology”, or MNT. One can imagine an artificial nanotechnology that uses some of the same operating principles and design philosophy as cell biology, but executes them in synthetic materials (as discussed in Soft Machines). Undoubtedly other approaches to radical nanotechnology that have not yet been conceived could work too. In comparing different potential approaches, we need to assess both how easy in practise it is going to be to implement them, and what their ultimate capabilities are likely to be.
  • Does Nanosystems contain obvious errors that can quickly be shown to invalidate it?
    No. It’s a carefully written book that reflects well the state of science in relevant fields at the time of writing. Drexler’s proposals for radical nanotechnology do not obviously break physical laws. There are difficulties, though, of two types. Firstly, in many cases, Drexler used the best tools available at the time of writing, and makes plausible estimates in the face of considerable uncertainty. Since then, though, nanoscale science has considerably advanced and in some places the picture needs to be revised. Secondly, many proposals in Nanosystems are not fully worked out, and many vital components and mechanisms remain at the level of “black boxes”.
  • How easy will it be to implement the vision of diamondoid-based nanotechnology outlined in Nanosystems?
    The Center for Responsible Nanotechnology writes “A fabricator within a decade is plausible – maybe even sooner”. I think this timeline would be highly implausible even if all the underlying science was under control, and all that remained was the development of the technology. But the necessary science is very far from being understood. Firstly, there are important uncertainties about the effect on the proposed mechanisms, based as they are on the scaling down of macroscopic mechanical engineering principles, of ubiquitous features of nanoscale physics such as strong surface forces and Brownian motion. This will be particularly serious for devices intended to work in ambient conditions, rather than at very low temperatures at ultra-high vacuum, and I believe that the problems this will cause are seriously underestimated by proponents of MNT. Secondly, there is currently a huge gap in the implementation pathway. Even proponents of MNT disagree on the best way to reach their goal from our current level of technology. Drexler favours soft and biomimetic approaches (see both Nanosystems, and his letter to Physics World responding to my article), though the means of moving from soft to hard systems remains unclear. Robert Freitas and Ralph Merkle favour a more direct route using diamondoid mechanosynthesis; see the ongoing discussion with Philip Moriarty here for the difficulties that this proposal may face. In conclusion, even if diamondoid-based nanotechnology does not break any physical laws in principle, I believe in practise that it will be very much more difficult to implement than its proponents think.
  • Will the advantages of the diamondoid-based nanotechnology outlined in Nanosystems be so great as to make it worth persisting to overcome these difficulties, whatever the cost?
    This depends what you want to use the technology for. Much of the emphasis from proponents of MNT is on using the technology to manufacture artefacts. But arguably the impacts of nanotechnology will be much more important and far-reaching in areas like information processing, energy storage and transduction, and medicine, where the benefits of diamond as a structural material will be much less relevant. In these areas, evolutionary nanotechnology and other approaches to radical nanotechnology, like soft nanotechnology and bio-nanotechnology, may have a greater impact on a much shorter timescale.
  • If the diamondoid-based nanotechnology proposed in Nanosystems proves to be impossible or impractical to implement, does that mean that nanotechnology will have only marginal impacts on the economy and society?
    Not necessarily. See this post -Even if Drexler is wrong, nanotechnology will have far-reaching impacts – for a discussion.
  • Small but deadly?

    Wednesday, December 22nd, 2004

    A piece in today’s Independent newspaper – Small but deadly – neatly illustrates much of what is good and bad about mainstream journalism about nanotechnology today.

    The main text of the story reports a study from the Rice group reporting on the mechanism by which unmodified buckminster fullerene damages human cells, and the way in which this toxicity is greatly reduced by attaching functional groups to the surface of the fullerene molecule. Although the story is not exactly news (the paper in question appeared on September 23rd, and was extensively reported elsewhere), the main text of the report is fairly clear, accurate and well written.

    But if the science reporting is good, the context in which the story is introduced is lamentable. The introductory paragraph moves quickly from Michael Crichton’s Prey, via self-replicating robots consuming the planet, to Prince Charles’s warning that nanotechnology could lead to a thalidomide-like health disaster.

    And if only the science journalist could have a quick word with the picture editor. Once again, the story is illustrated with a completely idiotic medical nanorobot image from the Science Photo Library’s extensive range of stupid nanotechnology graphics. To add insult to injury, this is described in the caption as a “computer simulation”.

    Is mechanosynthesis feasible? The debate moves up a gear.

    Thursday, December 16th, 2004

    Followers of the Drexlerian flavour of radical nanotechnology often accuse nanoscientists of ignoring their approach for reasons of politics or prejudice, and take the lack of detailed critiques of books like Nanosystems as evidence that the whole Drexlerian program is feasible, and indeed imminent. Scientists, on the hand, find the Drexlerian proposals too futuristic and too lacking in practical implementation details to be even worth criticising. The result is an ever-widening gulf between the increasingly bitter Drexlerites and a dismissive and contemptuous mainstream nanoscience community, which does neither side any good. So it’s a very positive development that Robert Freitas has presented a detailed scheme for achieving the first steps towards the mechanosynthesis of diamondoid nanostructures, and even more positive that Philip Moriarty has made a detailed critique of these proposals, based on his deep practical knowledge of scanning tunneling microscopy and surface growth processes.

    Philip’s critique is contained in an 8-page letter to The Center for Responsible Nanotechnology‘s Chris Phoenix. The letter was prompted by an approach from Chris, asking Philip to expand on the criticisms of the Drexlerian vision that I reported him making at our joint appearance at the Institute of Contemporary Arts. Chris has, in turn, replied to the letter, and will be publishing the whole correspondence on the CRN web-site in due course.

    The letter covers a lot of ground; at its heart is an exploration of some fundamental problems with the Freitas scheme – just how will a diamondoid cluster grow, and is the assumption that the mechanosynthesis tool-tip will grow in the necessary pyramid shape at all realistic? The answer to this seems to be, in all probability, no.

    Just as important as this critique of one specific proposal are the general comments Philip makes about the importance of proof-of-principle experiments and of the theory-experiment feedback loop. This gets to the heart of the gulf between conventional nanoscience and the followers of Drexler. To the latter, theoretical demonstrations of feasibility in principle are primary, and considerations of how one is going to achieve the goals are secondary engineering issues that don’t need detailed consideration now. But to nanoscientists like Philip, the devil is in the details. It’s these details that determine whether a theoretically possible outcome will in practise be achieved in 10 years, in 50 years, or never. The Drexlerites tend to say “if x doesn’t work, then we’ll just try y”. But the more and more specific systems we try out and have to discard, the further away we get from the MNT dream of a system that can make any combination of atoms consistent with chemistry.

    Freitas and Merkle have taken a very positive step in addressing these issues of implementation and experimental detail. The fact that the proposals can be criticised is positive too; in science this type of criticism isn’t destructive. It’s at the heart of the process by which science moves forward.

    Update – 26th January. The whole correspondence between Moriarty and Phoenix, including the original letter, is now available for download here.

    Nanorobotics in the UK

    Wednesday, December 15th, 2004

    Nanoscientists would love to have an instrument which would allow them to see what they were doing while they picked individual molecules up and moved them around. At the moment researchers can manipulate individual molecules with scanning probe microscopy techniques, and high resolution transmission electron microscopy allows structures to be visualised with resolutions better than an individual atom. A major grant has recently been awarded to a team of UK scientists to combine these technologies, developing instrumentation that combines nanoscale actuators with high resolution electron microscopy. The result should be a new tool for manipulating single atoms and molecules while they are being imaged, with atomic resolution, in three dimensions.

    The ��2.3 million ($4.4 million) grant comes from the UK government’s Basic Technology Program. It is led by Beverley Inkson and Guenter Moebus here at the University of Sheffield, and also involves the nanoscience group at the University of Nottingham.

    simulated interaction between electron beam and surface
    The image is a simulated interaction between an electron beam and a surface, showing the size of the electron beam to scale with the atoms making up the surface. The immediate uses that are foreseen for this technology are mostly as a nanoscale research tool, with applications to research in nanoscale electronic, magnetic and electromechanical devices, the manipulation of fullerenes and nanoparticles, nanoscale friction and wear, biomaterials, and systems for carrying out quantum information processing.

    More details can be found in this one-page PDF.

    Nanotechnology: making new combinations of atoms never before seen in Nature

    Tuesday, December 14th, 2004

    One thread of the narrative being constructed by anti-nanotechnology groups like ETC is that the reason nanotechnology is so fundamentally dangerous is that it allows one to build completely new and unnatural forms of matter, from the bottom up, by manipulating the most basic ingredients of matter itself, the atoms. It sounds scary, and it fits into their broader narrative rather well. Scientists, having impiously dared to manipulate the building blocks of life in genetic engineering, have now gone one step further, and propose to meddle with the very basis of matter itself, producing new combinations of atoms never yet before seen in nature. Superficially, this view is supported by some of the rhetoric of the nanotechnologists themselves, for example in the title of the National Science and Technology Council report, Nanotechnology: shaping the world atom by atom. The kind of spin anti-nanotechnology activists put on this is very succintly summed up in this phrase from the recent UK protesters who dressed as angels to disrupt a nanotechnology conference: ���The same greedy corporations who messed with the genetic basis of life are now seeking to alter and privatize nature right down to the atomic level���. This just goes to show that the angelic hosts haven’t been following events on earth very closely over the last six thousand years.

    The creation of new combinations of atoms to make unnatural materials is indeed a profoundly transformative technology with the potential to turn human societies upside down. The trouble is that this transformation began about 6000 years ago, with the discovery of copper smelting. The following millenia have seen rather a lot of the alteration and privatisation of nature as the crafts of metallurgy and alchemy have slowly turned into chemistry and materials science. There’s been a lot of thought, too, over the years, about what this means for the relationship between man and nature; a recent book, Promethean Fire by William Newman, gives a fascinating account of the reaction of philosophers and churchmen to the medieval alchemists.

    If there is nothing fundamentally new or different about nanomaterials, does this mean that the fuss about nanotechnology is all about nothing? No, and here I disagree with those eminent scientists (mostly, as it happens, chemists) who say about nanotechnology “it’s just chemistry”. The transformative consequences of nanotechnology will come, not from simple nanomaterials, but from devices that manipulate energy, information or other matter on the nanoscale. Some of the effects of these nanotechnologies will be very positive, others, potentially, less so. But in debating these issues we need to have some awareness of how the history of technology has got us to where we are today, and we need to resist the temptation to slide lazily into the sort of prepackaged sets of beliefs that angels seem to come equipped with.

    What happened to Prey – the Movie?

    Thursday, December 9th, 2004

    The news that Michael Crichton has a new book out – State of Fear – reminds me that it wasn’t long ago that we were all worrying that mobs of anxious citizens would be pouring out of cinemas with a horror of nanotechnology induced by the film of his previous novel, Prey. But after a flurry of reports at the time that the film rights had been bought by Fox, even before the novel came out, there seems to have been nothing but silence. Meanwhile environmentalists are cheerfully getting on with their protests against nanotechnology regardless. And who are the villains of the latest Crichton blockbuster? These very same environmentalists, with their irrational opposition to global warming. Now I’m really confused.

    Superconductivity in diamond

    Wednesday, December 8th, 2004

    A flurry of reports in the current edition of Physical Review Letters(Bustarret et al., Blase et al., Boeri et al., Roesch et al) build on the discovery earlier this year that boron doped diamond is a superconductor. I’m surprised we haven’t heard more of this from MNT enthusiasts, who are usually fascinated by anything to do with diamond. The transition temperature, admittedly, is a very chilly 4 Kelvin.

    A video seminar on soft nanotechnology

    Tuesday, December 7th, 2004

    You can see a video seminar on soft nanotechnology jointly given by me and my colleague Tony Ryan on the web here. This isn’t exactly new; it was done a couple of years ago, but I’ve only just come across the web version, which was done as an experiment in e-learning under the aegis of the Worldwide Universities Network, an alliance of Universities in Europe, the USA and China. You’ll need a fast internet connection and the Shockwave plug-in to view it.

    Renewable energy and incremental nanotechnology

    Thursday, December 2nd, 2004

    Over the next fifty years, mankind is going to have to find large-scale primary energy sources that aren’t based on fossil fuels. Even if stocks of oil and gas don’t start to run out, the effects of man-made global warming are likely to become so pressing that the most die-hard climate-change sceptics will begin to change their tune. Meanwhile, the inhabitants of the rapidly developing countries of Asia will demand western-style standards of living, which in turn will demand western levels of energy use. Can nanotechnology help deliver the energy needed for all the world to have a decent standard of living on a sustainable basis?

    Although wind and hydroelectric energy can make significant dents in total energy requirements, it seems that only two non-fossil primary energy sources really have the potential to replace fossil fuels completely. These are nuclear fission and photovoltaics (solar cells). Nuclear power has well known problems, though there have been recent signs of a change of heart by some environmentalists, notably James Lovelock, about this. Solar power is viable, in the sense that enough sunlight falls on the earth to meet all our needs, but the capital expense of current solar cell technology is too great for it to be economically viable, except in areas remote from the electricity grid.

    To make a dent in the world’s total power needs we’re talking about bringing in many gigawatts (GW) of capacity per year (total electricity generating capacity in the UK was around 70 GW in 2002, in the USA it was 905 GW). Roughly speaking 65 million square meters (i.e. 65 square kilometers) of a moderately efficient photovoltaic gives you a GW of power. Here we see the problem of conventional silicon solar cells: a silicon wafer production plant with a 30 cm wafer process produces only 88,000 square meters a year; the cost is high and so is the energy intensity of the process, to the extent that it takes about 4 years to pay back the energy used in manufacture. We need to be able to make solar cells on a continuous basis, using a roll-to-roll process, more like a high volume printing press. A typical printing press takes just a few hours to process the same area of material as a silicon plant does in a year; at this rate we’re approaching the possibility of being able to make a GW’s worth of solar cells (roughly comparable to the output of a nuclear power station) from a year’s output from one production line. Several new technologies based on incremental nanotechnology promise to give us solar cells made by just this sort of cheap, large scale, low energy manufacturing process.

    The most famous, and probably best developed technology is the Graetzel cell, invented by Michael Graetzel of the EPFL, Lausanne. This relies on nanostructured titanium dioxide whose surfaces are coated by a dye; the nanoparticles are then embedded in a polymer electrolyte to make a thin film which can be coated onto a plastic sheet. This process is being commercialised by a number of companies, including Konarka and Sustainable Technologies International. Other technologies use nanostructured forms of different kinds of semiconductors; companies involved include Nanosys, Nanosolar, and Solaris. A third class of non-conventional photovoltaics uses semiconducting polymers of the kind used in polymer light emitting diode displays, sometimes in conjunction with fullerenes. These technologies still need to make improvements to their efficiencies and lifetimes to be fully viable, but progress is rapid, and all offer the crucial benefit of low energy, large scale manufacturability.

    It’s not at all clear which of these technologies will be the first to deliver the promised benefits. We shouldn’t forget that more conventional technologies, like thin film amorphous silicon, are also advancing fast – Unisolar has a commercial reel-to-reel process for producing this type of solar cell in quantity, with a projected annual production of 30 MW (i.e. 3% of a nuclear power station) coming soon. But it does seem as though this is one area where incremental nanotechnology could have a transformational and positive effect on the economy and the environment.

    This discussion draws on two recent articles: Manufacturing and commercialization issues in organic electronics, by J.R. Sheats, Journal of Materials Research 19 1974 (2004), and Organic photovoltaics: technology and market”, by C.J. Brabec, Solar Energy Materials and Solar Cells, 83 273 (2004).