Category: General

The molecule DNA has emerged as the building block of choice for making precise, self-assembled nanoscale structures (in the laboratory, at least) – the specificity of the base-pair interaction makes it possible to design DNA sequences which will spontaneously form rather intricate structures. The field was founded by NYU’s Nadrian Seeman; I’ve written here before about DNA nanostructures from Erik Winfree and Paul Rothemund at Caltech, and Andrew Turberfield at Oxford. Now from Turberfield’s group comes a paper showing that DNA has the potential not just to make static structures, but to make functioning machines.

The paper, Coordinated Chemomechanical Cycles: A Mechanism for Autonomous Molecular Motion (abstract, subscription required for full article), by Simon Green, Jonathan Bath and Andrew Turberfield , was published in Physical Review Letters a couple of weeks ago (see also this Physical Review Focus article). The aim of the research was to design a synthetic analogue of the molecular motors that are so important in biology – these convert chemical energy (in biology, typically from a fuel like the energy carrying molecule ATP) into mechanical energy. One important class of biological motors consists of something like a molecular walker which moves along a track – for example, the motor molecule myosin walks along an actin track to make our muscles contract, while kinesin walks along the microtubule network inside a cell to deliver molecules to where they are needed (to see how this works take a look at this video from Ron Vale at UCSF). What Turberfield’s group has demonstrated is a synthetic DNA based motor that walks along a DNA track when fed with a chemical fuel.

The way molecular motors work is very different to any motor we know about in our macroscopic world. They’re the archetypal “soft machines”, whose operation depends on the constant Brownian motion of the wet nanoscale world. The animation below shows a schematic of the motor cycle of the DNA motor. At rest, the motor is stuck down by both feet onto the track, which is also made of DNA. The first step is that a fuel molecule displaces one foot from the track; the foot part of the motor then catalyses the combination of this fuel molecule with another fuel molecule from the solution, releasing some chemical energy in the process. The foot is then free to bind back to the track again. The key point is that all these binding and unbinding events, together with the flexing of the components of the motor that allow it to pick up and put down its feet on the track are driven by the random buffetings of Brownian motion. What makes it work as a motor is the fact that there’s an asymmetry to which foot is more likely to be displaced from the track; when the foot sticks back each of the two possible positions is equally probable. This means that although each step in the motor is probabalistic, not deterministic, there’s a net movement, on average, in one direction. It’s the input of chemical energy of the fuel that breaks the symmetry between forward and backward motion, making this motor a physical realisation of a “Brownian ratchet”.

In this paper the authors don’t directly show the motor in action – rather, they demonstrate experimentally the presence of the various bound and unbound states. But this does allow them to make a good estimate of the forces that the motor can be expected to exert – a few picoNewtons, very much in the ball-park of the forces exerted by biological motors.

Schematic showing the operation of the DNA motor. Animation by Jonathan Bath.

It’s being reported that US President-Elect Obama will name the physicist Steven Chu as his Energy Secretary. Chu won the Nobel prize in 1997 (with Bill Phillips and Claude Cohen-Tannoudji) for his work on cooling and trapping atoms with laser light. One of the spin-offs from his discovery was the development of the “optical tweezers” technique, by which micron-size particles can be held and manipulated by a highly focused laser beam. Chu himself used this technique to manipulate individual DNA molecules, directly verifying the reptation theory of motion of long, entangled molecules. The technique has since become one of the mainstays of single molecule biophysics, used by a number of groups to characterise the properties of biological molecular motors.

Chu is currently director of the Lawrence Berkeley National Laboratory, where one of his major initiatives has been to launch a major initiative to develop economic methods for harnessing solar energy on a large scale – Helios. One can get some idea of what Chu’s priorities are from looking at recent talks he has given, for example this one: The energy problem and how we might solve it (PDF). This concludes with these words: ‘“We believe that aggressive support of energy science and technology, coupled with incentives that accelerate the concurrent development and deployment of innovative solutions, can transform the entire landscape of energy demand and supply … What the world does in the coming decade will have enormous consequences that will last for centuries; it is imperative that we begin without further delay.”

The BBC’s Radio 4 has been running a series of short programs – Street Science – featuring scientists being sent out onto the streets to engage random members of the public about controversial bits of science. The latest program dealt with nanotechnology, with my friend and colleague Tony Ryan getting a good hearing in the centre of Sheffield. The programme (RealPlayer file) is well worth a listen, as he talks about applications in medicine and novel photovoltaics, how 2-in-1 shampoo works, Fantastic Voyage, Prince Charles and grey goo, the potential dangers of carbon nanotubes, and why nanosilver-based odour resistant socks may not be a good idea.

I’ve just done a brief interview with a journalist for the BBC’s Focus magazine, about the three popular science books on nanotechnology that have most inspired me. I’ve already written about my nanotechnology bookshelf, but this time when I came to choose my three favourite books to talk about it turns out that they weren’t directly about nanotechnology at all. So here’s my alternative list of three non-nanotechnology books that I think all nanotechnologists could benefit from reading.

The New Science of Strong Materials by J.E. Gordon. To say that this is the best book ever written about materials science might not sound like that high praise, but I was hugely inspired by this book when I read it as a teenager, and every time I re-read it I find in it another insight. It was first published in 1968, long before anyone was talking about nanotechnology, but it beautifully lays out the principles by which one might design materials from first principles, relating macroscopic properties to the ways in which their atoms and molecules are arranged, principles which even now are not always as well known as they should be to people who write about nanotechnology. It’s a forward looking book, but it’s also full of incidental detail about the history of technology and the science that has underlain the skills of craftsmen using materials through the ages. It also looks to the natural world, discussing what makes materials of biological origin, like wood, so good.

The Self-Made Tapestry by Philip Ball. Part of the appeal of this is the beauty of the pictures, depicting the familiar natural patterns of clouds and sand-dunes, as well as the intricate nanoscale structure of self-assembled block copolymer phases and the shells of diatoms. But alongside the illustrations there is an accurate and clear account of the principles of self-assembly and self-organisation, that cause these intricate patterns to emerge, not through the execution of any centralised plan, but as a result of the application of simple rules describing the interactions of the components of these systems.

Out of Control by Kevin Kelly. This is also about emergence, but it casts its net much more widely, to consider swarm behaviour in insects, economics and industrial ecologies, and flocks of insect-like robots. The common theme is the idea that one can gain power by relinquishing control, harnessing the power of adaptation and evolution in complex systems in which non-trivial behaviour arises from the collective actions of many interacting objects or agents. The style is evangelical, perhaps to the extent of overselling some of these ideas, and some may, like me, not be wholly comfortable with the libertarian outlook that underlies the extension of these ideas into political directions, but I still find it hugely provocative and exciting.

The following essay is the pre-edited version of a piece of mine that will be published in a forthcoming book “Human Futures: Art in an Age of Uncertainty”, edited by Andy Miah and published by FACT (Foundation for Art and Creative Technology) & Liverpool University Press.

The days when our society was bound together by a single shared faith seem long gone. But at some level, most of us share a faith in technology, a faith that next year we’ll be able to buy a faster computer, a digital camera with more megapixels, or an MP3 player that holds more songs, and it will cost us less. For some, this is part of a broader faith in the power of science and technology both to deliver a better life and to give a coherent way of thinking about the world. Others might have a more nuanced view, seeing the results of techno-science as a very much a mixed blessing, and accepting the gadgets, while rejecting the scientific worldview. For better or worse, though, we’re in the state we’re in now because of technology, and indeed we existentially depend on it. But it’s equally clear that the technology we have can’t be sustained. Whatever happens, this tension must be resolved; whether we believe in progress or not, things can’t go on as they are.

There’s a new set of emerging technologies to bring these arguments into focus. Nanotechnology manipulates matter at the level of atoms and molecules, and promises a new level of control over the material world[i]. Biology has already moved from being an essentially descriptive and explanatory activity, and it’s now taking on the character of a project to intervene in and reshape the living world. Up to now, the achievements of biotechnology have come from fairly modest modifications to biological systems, but a new discipline of synthetic biology is currently emerging, with the much more ambitious goal of a wholesale reengineering of living systems for human purposes, and possibly creating entirely novel living systems. In large organisms like humans, we’re starting to appreciate the complexities of communications within and between the cells that together make up the organism; it’s this understanding of the rich social lives of cells that will make possible the development of stem cell therapies and tissue engineering. Information technology both enables and is enabled by these advances; it’s computing power that underlay the decoding of the human genome and which drives the development of sciences like bioinformatics, that are giving us the tools to understand the informational basis of life. The other side of the coin is that it is developments in nanotechnology that are what drives the relentless increase in computing power that is obvious to every consumer; in the near future similar advances will contribute to the growing importance of the computer as an invisible component of the fabric of life – ubiquitous computing. Perhaps of most significance of all to our conceptions of what it means to be human, cognitive science expands our understanding of how the brain works as an organ of information processing, prompting dreams both of a reductionist understanding of consciousness and the possibility of augmenting the functionality of the brain.

What will all these bewildering developments mean for the way the human experience evolves over the coming decades? Let’s get some perspective by reminding ourselves of technology’s role in getting us to where we are now.

No-one can doubt that our lives now are hugely different to the lives of our forbears two hundred years ago, and that this dramatic transformation has come about largely through new technologies. The world of material things – food, buildings, clothes, tools – has been transformed by new materials and processes, with mass production bringing complex artefacts within reach of everyone. Information and communications have been transformed; first telephones removed the need for physical presence for two-way communication, then computers and the internet have come together to give unprecedented ways of storing, accessing and processing a vast universe of information. Now all these technologies have converged and become ubiquitous through mobile telephony and wireless networking. Meanwhile life expectancy has doubled, through a combination of material sufficiency, the development of scientific medicine, and the implementation of public health measures. We’ve started to assert a new control over human biology – we already take for granted control over our reproduction through the contraceptive pill and assisted fertility, and we are beginning to anticipate a future in which we’ll have access to bodily repairs and spare parts, through the promise of tissue engineering and stem cell therapy.

It’s easy to be dazzled by all that technology has achieved, but it’s important to remember that these developments have all been underpinned by a single factor – the availability of easily accessible, concentrated forms of energy. None of this would have happened if we had not been able to fuel our civilisation by extracting black stuff from the ground and burning it. In 1800, the total energy consumption in the UK amounted to about 20 GJ per person per year. By 1900 this figure had increased by more than a factor of five, and today we use 175 GJ. Since this is predominantly in the form of fossil fuels, one graphic way of restating this figure is that it amounts to the equivalent of more than 4 tonnes of oil per person per year[ii].

It’s obvious to everyone that they use fossil fuel energy when they put petrol in their car, or turn the house heating on. But it’s important to appreciate how much energy is embodied in the material things around us, in our built environment and the artefacts we use. It takes a tonne and a quarter of oil to make ten tonnes of cement, and eight and a quarter tonnes of oil to make ten tonnes of steel. For a really energy hungry material like aluminium, it takes nearly four tonnes of oil to produce a single tonne. And if we build with oil, and make things out of oil, in effect we eat oil too, thanks to our reliance on intensive agriculture with its high energy inputs. To grow ten tonnes of wheat (roughly the output of a hectare, in the most favourable circumstances) takes 200 kg of artificial fertiliser, which itself embodies 130 kg of oil, as well as the input of another 200 kg of oil in other energy inputs.

Some people have the conceit that we’ve moved beyond a dirty old economy of power stations and steel works to a new, weightless economy based on processing information. Nothing could be further from the truth; in addition to our continuing dependence on material things, with their substantial embodiment of energy, information and communications technology itself needs a surprisingly large energy input. The ICT industry in the UK is actually responsible for a comparable share of carbon dioxide generation to aviation. The energy consumption of that giant of the modern information economy, Google, is a closely guarded secret; what is clear, though, is that the choice of location of its data centres is driven by the need to be close to reliable, cheap power, like hydroelectric power plants or nuclear power stations, in much the same way that aluminium smelters are sited.

Perhaps the most complex and interesting relationship is that between energy use and measures of health and physical well-being, like infant mortality and life expectancy. It’s clear, both from the record of history and the correlation of these figures with energy use for less well developed countries at the moment, that there’s a strong correlation between per capita energy use and life expectancy, at the lower end of the range. It seems that increasing per capita energy use up to 60 or 70 GJ per year brings substantial benefits, presumably by ensuring that people are reasonably well nourished, and allowing basic public health measures like access to clean water and having a working sewerage system. Further improvements result from increasing energy consumption above this, presumably by enabling increasingly comprehensive medical services, but beyond a per capita consumption around 110 GJ a year there is very little correlation between energy use and life expectancy. The lesson of this is that, while it is clear that material insufficiency is bad for one’s health, sometimes excess can have its own problems.

This emphasis on our dependence on fossil fuel energy should make it clear, whatever the prospects for exciting new developments in the future, there is a certain fragility to our situation. The large scale use of fossil fuels has come at a price – in man-made climate change – whose full dimensions we don’t yet know, and we are once again seeing problems of pressures on resources like food and fuel. Food shortages and bad harvests remind us that technology hasn’t allowed us to transcend nature – we’re still dependent on the rains arriving at the right time in the right quantity. We’ve influenced the climate, on which we depend, but in ways that are uncontrolled and unpredicted. The lessons of history teach us that a societal collapse is a real possibility, and one of the consequences of this would be an abrupt end to the hopes of further technological progress[iii].

We can hope that these emerging technologies themselves can help avert this kind of disastrous outcome. The only renewable energy source that realistically has the capacity to underpin a large-scale, industrial society is solar energy, but current technologies for harvesting this are too expensive and cannot be produced on anything like the scales needed to make a serious dent in the world’s energy needs. There is a real possibility that nanotechnology will change this situation, making possible the use of solar energy on very large scales. Other developments – for example, in batteries and fuel cells – would then allow us to store and distribute this energy, while we could anticipate a further continuation of the trends that allow us to do more with less, reducing the energy input required to achieve a given level of prosperity.

Computers will probably go on getting faster, with the current exponential growth of computing power (Moore’s law) continuing for perhaps ten more years. After that, we’re relying on new developments in nanotechnology to allow us to keep that trajectory going. Less obvious, but in some ways more interesting, will be the ways computing power becomes seamlessly integrated into the material fabric of life. One of the areas this will impact is medicine; developments in sensors should mean that we diagnose diseases earlier and can personalise treatments to the particularities of an individual’s biology. Therapies, too, will become more effective and less prone to side-effects, thanks to nanoscale delivery devices for targeting drugs and the development of engineered replacement tissues and organs.

So perhaps our optimistic goal for the next fifty years should be that these emerging technologies contribute to making a prosperous global society on a sustainable basis. A steady world population should universally enjoy long and pain-free lives at a decent standard of living, this being underpinned by sustainable technologies, in particular renewable energy from the sun, and supported by a ubiquitous (but largely invisible) infrastructure of ambient computing, distributed sensing, and responsive materials.

For some, this level of ambition for technology isn’t enough. Instead they seek transcendence through technology and, through human enhancement, our transfiguration to qualitatively different and superior types of beings. It’s the technological trends we’ve discussed already that are invoked to support this view, but with a particularly superlative vision of the potential of technology[iv]. For example, there’s an extrapolation from the existing developments of nanotechnology, via Drexler’s conception of atom-by-atom nanomanufacturing[v], to a world of superabundance, in which any material object is available at no cost. From modern medicine, and the future promise of nanomedicine, there’s the promise of superlongevity – the idea that a “cure” for the “disease” of ageing is imminent, and the serious suggestion that people alive today might live for a thousand years[vi]. From some combination of the development of ever-faster computers and the possibility of the augmentation of human mental capabilities by implants, comes the idea that we will shortly create a greater than human intelligence, either as a purely artificial intelligence in a computer, or through a radical enhancement of a human mind. This superintelligence is anticipated to be the greatest superlative technology of all, as by applying its own intelligence to itself it will be able rapidly and recursively to improve all these technologies, including its own intelligence. This will lead to a moment of ineffably rapid technological and societal change called, by its devotees, the Singularity[vii].

The technical bases for these superlative predictions are strongly contested by researchers in the relevant fields[viii]. This doesn’t seem to have a great deal of impact on the vehemence with which such views are held by those (largely online) communities transhumanists and singularitarians for whom these shared beliefs define a shared identity. The essentially eschatological character of singularitarian beliefs is obvious – it’s this that is well captured in the dismissive epithet “the rapture of the nerds”. While some proponents of these views have an aggressively rational, atheist outlook, others are explicit in highlighting a spiritual dimension to their belief, in a cosmological outlook that seems to owe something, whether consciously or unconsciously, to the Catholic mystic Teilhard de Chardin[ix]. Belief in the singularity, then, as well as being a symptom of a particular moment of rapid technological change, should perhaps be placed in that tradition of millennial, utopian thinking that’s been a recurring feature in Western thought for many centuries.

For me, the main sin of singularitarianism is one shared much more widely – that is the idea of technological determinism. This is the idea that technology has an autonomous, predictable, momentum of its own, largely beyond social and political influence, and that societal and economic changes are governed by these technological developments. It’s the everyday observation of the rapidity of technological change that gives this view such force; what keeps new, faster computers appearing in the shops on schedule is Moore’s law. This is the observation, made in 1965 by Gordon Moore, the founder of the microprocessor company Intel, that computer power is growing exponentially, with the number of transistors on a single chip roughly doubling every two years. To futurists like Kurzweil, Moore’s law is simply one example of a more general rule of exponential technological growth. But simply to give Moore’s observation the name “law” is to mistake its character in fundamental ways. It isn’t a law; it is a self-fulfilling prophecy, a way of coordinating and orchestrating the deliberate and planned action of the many independent actors in the semiconductor industry and in commercial and academic research and development, in the pursuit of a common goal of continuous incremental improvement in their products. Moore’s law is not a law describing the way technology develops as some kind of independent force, it is a tool for coordinating and planning human action.

We need to be very aware that technology need not advance at all; it depends on a set of stable societal and economic arrangements that aren’t by any means guaranteed. If there’s a collapse of society due to resource shortage or runaway climate change that will bring an abrupt end to Moore’s law and to all kinds of other progress. But a more optimistic view is to assert that we aren’t slaves to technology as an external, autonomous force; instead, technology is a product of society and our aspiration should be that it is directed by society to promote widely shared goals.

i For an overview, see “Soft Machines: nanotechnology and life”, Richard A.L. Jones, Oxford University Press (2004).

ii An excellent overview of the role of energy in modern society can be found in “Energy in Nature and Society”, Vaclav Smil, MIT Press, Cambridge MA, 2008, on which the subsequent discussion extensively draws.

iii This point is eloquently made by Jared Diamond in “Collapse: how societies choose to fail or succeed”, Viking (2005).

iv This characterisation of the “Superlative technology discourse” owes much to Dale Carrico.

v K.E. Drexler, “Engines of Creation: the coming era of nanotechnology” (Anchor, 1987) and K.E. Drexler, “Nanosystems: molecular machinery, manufacturing and computation” (Wiley, 1992).

vi Aubrey de Gray and Michael Rae, “Ending Ageing, the rejuvenation strategies that could reverse human ageing in our lifetime” (St Martins Press, 2007)

vii Ray Kurzweil, “The Singularity is Near: when humans transcend biology” (Penguin, 2006)

viii See, for example, the essays in a special issue of IEEE Spectrum: “The Singularity: a special report”, June 2008 , including my own piece “Rupturing the Nanotech Rapture”. For a critique of proposals for radical life extension, see “Science fact and the SENS agenda”, Warner et al, EMBO reports 6, 11, 1006-1008 (2005) (subscription required).

ix For an example, consider this quotation from Ray Kurzweil’s “The Singularity is Near”: “Evolution moves towards greater complexity, greater elegance, greater knowledge, greater intelligence, greater beauty, greater creativity and greater levels of subtle attribures such as love. In every monotheistic trandition God is likewise described as all of these qualities, only without any limitation: infinite knowledge, infinite intelligence, infinite beauty, infinite creativity and infinite love, and so on. Of course, even the accelerating growth of evolution never achieves an infinite level, but as it explodes exponentially it certainly moves rapidly in that direction. So evolution moves inexorably toward this conception of God, although never quite reaching this ideal. We can regard, therefore, the freeing of our thinking from the severe limitations of its biological form to be an essentially spiritual undertaking”.