Nanotechnology Feynman’s fancy Richard Feynman’s famous talk on atom-by-atom assembly is often credited with kick-starting nanotechnology. Fifty years on, Philip Ball investigates how influential it really was KEVIN FLEMING / CORBIS / FLEMING KEVIN 58 | Chemistry World | January 2009 www.chemistryworld.org Fifty years ago, the near-legendary might be wise to stop pretending microscope (STM) to manipulate In short physicist Richard Feynman of the that his address to the APS was individual xenon atoms. These were California Institute of Technology the ‘birth of nanotechnology,’ that Nobel prize winner adsorbed on the surface of nickel, (Caltech) gave a talk called There’s needn’t prevent us from relishing the Richard Feynman is often creating letters five atoms high and plenty of room at the bottom to spectacle of a genius giving free rein linked to the ‘birth of achieving a data storage density over the American Physical Society’s to his imagination. It was, according nanotechnology’ 100 times greater than Feynman’s West Coast section. He outlined a to George Whitesides of Harvard Fifty years ago, conservative estimate for what might vision of what would later be called University, US, ‘yet more validation, Feynman gave an be needed to write with atoms. nanotechnology, imagining ‘that we if any were needed, of Feynman’s imaginative talk outlining Indeed, one could say that could arrange atoms one by one, just perceptiveness and openness to new a nano vision, where Feynman didn’t think small enough. as we want them’. The rest is history. ideas’. atoms can be arranged He ended by offering two $1000 But what sort of history? Did one by one prizes (big money in 1959): one to ‘the Feynman’s talk, published the Sacred text Feynman offered first guy who can take the information following year in Caltech’s house It is hard not to be impressed at the cash prizes for those on the page of a book and put it on an magazine Engineering and science, prescience of much of what Feynman who could solve his nano area 1/25 000 smaller in linear scale,’ really kick-start nanotechnology, or had to say. ‘People tell me about challenges the other to ‘the first guy who makes is that just a convenient fiction to miniaturisation, and how far it has Feynman was a an operating electric motor which can link this emerging field to a colourful progressed today,’ he said. ‘There is a visionary and yet he be controlled from the outside and visionary? device on the market, they tell me, failed to appreciate the … is only 1/64 inch cube’. The latter There are three ways of by which you can write the Lord’s role that chemistry would challenge was far too easy, or rather, approaching this question. One is to Prayer on the head of a pin. But play in nanotechnology it underestimated the dexterity of look at what Feynman said and ask that’s nothing … Why can we not engineers: just months later, William how it relates to what nanotech is now write the entire 24 volumes of the McLellan of Caltech claimed the prize about. Another is to see what effect Encyclopaedia Britannica on the head with a device made by hand, which his talk actually had on the science of a pin?’ now sits in a niche in the corridors of and engineering of his time. And He estimated that this might Caltech (its coils burnt out long ago). the third is to ask researchers now involve making dots 32 atoms across In fact, McLellan made 10 of them, actively engaged in nanotechnology to create the dot matrices for the half- with crude tools including toothpicks whether Feynman’s talk holds any tone photos in the encyclopaedia. and paint brushes. ‘He really didn’t inspiration or insight for them. How do you write that small? believe it could be done,’ McLellan All three lines of inquiry point he asked. He predicted that the says. ‘But he found out.’ to a rather different story from answer might involve rearranging The book challenge took rather the one generally told. Feynman’s individual atoms. ‘Feynman did in a longer – it was met in 1985, three years talk didn’t in any sense start visionary way predict atomic-scale before Feynman’s death from cancer, nanotechnology. It didn’t really nanofabrication,’ says Cees Dekker of by Tom Newman, a graduate student stimulate any new research at the Technical University of Delft in at Stanford University, US, using all, although the miniaturisation the Netherlands, who has conducted electron-beam lithography. (He took challenges he set sparked some neat seminal work on carbon nanotube his text from Dickens.) Now there are feats of engineering. Indeed, some electronics. cheaper ways to write even smaller: of Feynman’s contemporaries even That vision was famously Chad Mirkin of Northwestern wondered if his intent was purely realised in 1990, when Don Eigler In 1960, William University in Evanston, Illinois, US, comic (which would have been and Erhard Schweizer of IBM’s McLellan used his has used dip-pen nanolithography, very much in character). Very little Almaden research centre in San Jose, lunch breaks to build where the tip of an atomic force of the later, foundational work in California, US, wrote their company’s a micromotor (0.5mm microscope is used as a nib to write nanotech drew on Feynman’s vision, name using the scanning tunnelling long), winning $1000 with a molecular ink that might then and most was conducted in complete serve as a mask in chemical etching ignorance of it. His talk can be seen of the surface, to inscribe some of in some respects as equivalent to the the very text quoted above from ‘prophetic’ writings of mediaeval Feynman’s talk, in letters about 60 scholars such as Roger Bacon and nanometres across. Nostradamus: flights of fancy that But one of the most significant later ages have combed for ‘evidence’ aspects of Feynman’s text is its of foresight, with their predictions of focus on information. It was already submarines, telephones and so on. becoming clear in 1959, a year after And yet such a revisionist take the invention of the integrated doesn’t quite do justice to the matter. circuit, that miniaturisation would be There is something in Feynman’s important in computer technology. Plenty of room that rings true, that ‘Work on the transistor had been reveals a fantastically creative mind miniaturising and miniaturising since imagining what might be possible its invention in 1947,’ says chemist and what we might do with it. Most Mark Ratner, also at Northwestern of all, Feynman can lay claim to a and author of Nanotechnology. real intellectual legacy, for he asked, ‘Whether the physics community as nanotechnologists do, what thought in those terms isn’t so clear, might be achieved by manipulating but Feynman was certainly aware matter on a truly tiny scale. Fifty of what the engineers’ thoughts years on, some of Feynman’s words were.’ All the same, this was six sound inevitably dated, but others years before Gordon Moore of Intel SCIENCE AND SOCIETY PICTURE LIBRARY / SCIENCE MUSEUM SCIENCE / LIBRARY PICTURE SOCIETY AND SCIENCE remain deeply pertinent. While it coined his renowned ‘law’ describing www.chemistryworld.org Chemistry World | January 2009 | 59 Nanotechnology of time thinking about computation and computers, but not much time thinking about molecules and the way they organise space and matter,’ says Ratner. ‘My guess is that if you presented him with a five-coordinate carbon atom, it wouldn’t have bothered him any more than a four- coordinate carbon atom would have. The soft-matter world was not his forte.’ Most crucially, he seems not to have appreciated (in fairness, neither did LAWRENCE LIVERMORE LABORATORY / SCIENCE PHOTO LIBRARY PHOTO SCIENCE / LABORATORY LIVERMORE LAWRENCE anyone else at the time) that nature’s prowess in nanotechnology relies heavily on the propensity of chemical systems to self-assemble. ‘I think that is the most important thing missing in the talk,’ says Ratner. ‘He talked about making things, but the making didn’t seem to involve self-assembly, but rather carving.’ ‘To my reading, Feynman gave the impression that chemistry was a distant discipline, whilst conceding that chemists could make anything,’ says Fraser Stoddart, now also at Northwestern University in Illinois, who has pioneered self-assembly of complex molecular structures. ‘This claim on behalf of the synthetic chemists of the late 1950s was simplistic, bordering on naïve.’ ‘He assumed that the science of small things would be dominated by physics,’ says Whitesides. ‘As it turns out, the engineering of small things has been dominated by electrical engineering and materials science, and by chemistry and molecular biology. So I would say that he got the “vector” entirely right, and the details entirely wrong.’ It’s sometimes said that, having aired his wild thoughts on atomic- scale engineering, Feynman never again returned to the subject. But he did. In 1983 he reconsidered his the shrinking of computer circuit something about it’. Today, molecular Nanotechnology came ideas in a talk at the Jet Propulsion elements, and there was none of the and cell biology are frequently cited alive with the advent Laboratory in California, entitled now commonplace presumption that not only as an ‘existence proof’ that of scanning tunnelling ‘Infinitesimal machinery,’ which data storage and processing would nanotechnology is possible but as a microscopy in the 1980s too found its way into print. (A video have to happen at an ever-decreasing rich store of ideas for how it might be of the talk also exists, showing that scale.