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Home , Don Eigler, Richard Feynman

Feynman’s fancy Richard Feynman’s famous talk on -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 Richard Feynman of the that his address to the APS was individual xenon . These were Institute of Technology the ‘birth of nanotechnology,’ that  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 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 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 , 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 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 . 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 -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 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, 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. Yet Feynman proclaimed that, achieved. But in 1959, says Dekker, the written texts of Feynman’s talks with a capacity for atom-craft, ‘all ‘people simply were not thinking present a sanitised version of his of the information that man has about biological structures in terms of freewheeling, often zany method carefully accumulated in all the books machines’. That Feynman did so only of verbal delivery.) Three things in the world can be written … in a cube six years after the discovery of the stand out. First, it’s notable that of material one two-hundredth of an information-encoding structure of many people don’t even know about inch wide.’ DNA was remarkable. ‘If I look at the this epilogue to Plenty of room – for What’s more, he recognised how two biggest technological revolutions sacred founding texts do not need much of this facility for manipulating in the past half century, I would (are perhaps even marred by) sequels. matter and storing information at mention information technology and Second, Feynman confessed in the the nanoscale was already apparent the molecular biology revolution,’ later talk that ‘there has been no in biological systems. In DNA, he says Dekker. ‘Feynman mentioned progress’ in figuring out what to do said, ‘approximately 50 atoms are both.’ with tiny machines. ‘I’m fascinated used for one bit of information about Where Feynman scores less and I don’t know why,’ he said, before the cell’. And biology ‘is not simply strongly is on the role of chemistry in admitting that ‘I know there’s already writing information; it is doing nanoscale engineering. ‘He spent a lot been a lot of laughter in the audience 60 | Chemistry World | January 2009 www.chemistryworld.org – just save it for the uses that I’m going suspects. One was that the science : an approach to to suggest for some of these devices, caught up. The STM and its ilk were ‘Evidence the development of general capabilities okay?’ Here, perhaps, he was still invented during the early 1980s suggests that for molecular manipulation. It cited limited by the preoccupations of his by of IBM’s research Feynman in the very first sentence, times. ‘He was thinking in the Sputnik laboratories in Zürich and his Feynman’s and went on to outline a vision of era,’ says Stoddart. ‘Health, collaborators, and ideas were at ‘microtechnology’ at the molecular and the environment were not on his at IBM and Calvin scale that Drexler later developed radar screen.’ Quate at Stanford University in first almost in his 1986 book Engines of creation, Third, the talk supplied the same California. Eigler says that ‘Feynman’s totally ignored’ which became the point of entry to mixture of sheer speculation and work would be on a dusty shelf nanotechnology for many lay readers. acute prescience that Plenty of room without Binnig. It was Binnig who Drexler’s vision aligned itself very evinced. He anticipated sacrificial- blew life into nano by creating the much with what Feynman seemed layer microfabrication, where thin machine that fired our imaginations’. to be saying. Where Feynman said films of material are deposited and Yet the inventors of these devices ‘it would be interesting in surgery if then evaporated to separate moving didn’t even know what Feynman you could swallow the surgeon. You parts in silicon micromotors. He had said. ‘Binnig and I neither heard put the mechanical surgeon inside talked about the problem of ‘stiction’ of Feynman’s paper until scanning the blood vessel and it goes into the – the adhesion of nanoscale moving tunnelling microscopy was widely heart and “looks” around,’ Drexler parts because of molecular-scale accepted in the scientific community conjured up images of nanoscale attractive forces – which is now … nor did any of our papers ever refer robots patrolling the bloodstream recognised as problematic for tiny to it,’ says Rohrer. Quate denies prior for blockages or invaders. Most machinery. And he mentioned ‘a knowledge of it, and Binnig told crucially, Feynman imagined a rather machine that computes and works by Toumey that even then he hadn’t K Eric Drexler created literal scaling down of macroscopic quantum-mechanical laws of physics’ read it. visions of molecular mechanical engineering in order – a quantum computer. The other reason for the rising machines which could to make ‘a billion tiny factories, fame of Feynman’s talk was more self-replicate models of each other, which are Any takers? controversial. In 1981 manufacturing simultaneously, For all its strengths and weaknesses, engineer K Eric drilling holes, stamping parts, and did anyone actually listen to Drexler published a so on’. Drexler seized on this idea, Feynman’s ideas? ‘Feynman was paper entitled elaborating in his subsequent, more Feynman,’ says Ratner, ‘and a lot of technical book Nanosystems (1992) people would listen to him who might on the notion of nanoscale cogs and not be willing to listen to people of levers made of diamond-like carbon lesser reputation, in part because he and coated where necessary with put things so beautifully.’ Yet if they lubricating molecular films. Most LAGUNA DESIGN / SCIENCE PHOTO LIBRARY PHOTO SCIENCE / DESIGN LAGUNA listened, it’s not clear that they were notoriously, Drexler considered inspired to act. In a myth-busting the notion of giving these nano- article of 2005 published, cheekily, machines the capability to build also in Engineering and science, copies of themselves – to replicate anthropologist Chris Toumey of – precipitating the storm-in-a- the University of South Carolina teacup of nanotechnological grey dissected the real ‘influence’ of goo that devours the world. Feynman’s talk. How many citations Drexler’s blueprint for did Plenty of room generate, Toumey nanotechnology has been asked? Until 1980, you could count criticised extensively, most them on your fingers: three in the famously by an acerbic exchange 1960s, four in the 1970s. And one with the late Richard Smalley of these, a survey of advances in of Rice University, a discoverer information technology in 1969, of nano’s poster molecule C60. called Feynman’s speculations Much of this criticism centres on about storing information in Drexler’s mechanistic literalism single atoms ‘completely and its apparent neglect of vacuous as far as the real chemical principles, which world is concerned’. restrict what is possible Even if that last by mechanical means but remark chalks up a also offer smarter ways of point for Feynman, achieving similar goals. the evidence That, however, isn’t the therefore point here. Even Drexler’s suggests that critics cannot deny that his ideas were he was hugely influential at first almost to the public visibility of totally ignored. nanotechnology in its early Then, from around days, boosted by Drexler’s 1980 until 2002, the founding of the Foresight growth in citations Institute in Palo Alto, increased exponentially. California, to promote the topic What made the difference? generally and Drexler’s ‘molecular Two things, Toumey machinery’ version of it in particular.

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content,’ says Gimzewski, ‘but more by the fact that he did speculate and was not the typical academic. He had character and was a bit crazy.’ Whether any of these speculations

SHELLEY GAZIN / CORBIS / GAZIN SHELLEY hit the mark is not really the point, he says. ‘He threw a bunch of darts, and some accidentally landed on where the future was going. He carpet- bombed the future.’ Whitesides believes that, for most researchers, an interest in what Feynman says comes post hoc: ‘My sense is that most people in nano become excited about it for their own reasons, and then lean on Feynman as part of their justification for their interest. Most scientists require “permission” to work in new areas, and Feynman provided that.’ For his own part, Whitesides says that Feynman’s talk ‘had no influence on what we have done. ‘Late on, I have read parts of it, but only parts. It has never seemed that relevant’. ‘Feynman had a dream, but he did not come up with a blueprint,’ says Stoddart. ‘Yet it would have been asking a lot of him to see much beyond what he did see and predict. He did not recognise the power of chemistry to drive nanotechnology in a meaningful way. He did, however, help to stimulate a number of chemists to start thinking about meaningful ways to do bottom-up manufacturing.’ Perhaps in the end the inspiration Feynman offers comes not from what he said, but from the fact that he said it at all. ‘In a world in which atoms and molecules and small structures were “not physics” and not fashionable,’ says Whitesides, ‘Feynman said “Oh yes they are and there is lots to do there!’” That took great imagination, says Ratner. ‘Bold speculative visions are wonderful, and imagination is crucial to the development and introduction And at every juncture, Drexler Feynman was full of the dye-stuffs and pharmaceutical of new scientific ideas. And took the opportunity to promote character and enjoyed industries.’ imagination was Feynman’s great Feynman’s talk as the foundational airing his wild thoughts stock in trade.’ text of the subject, perhaps because it In retrospect meshed so well with his own vision. Whether or not the true founders of Philip Ball is a science writer based in This may lead some chemists to the science of nanotechnology knew London, UK be sceptical of Feynman’s insights. of Feynman’s talk at the time, no one Jim Gimzewski, a specialist in STM who enters this field can be ignorant Further reading  M Ratner and D Ratner, Nanotechnology: a nano-manipulation at the University of it now. What do they make of it? Is gentle introduction to the next big idea, Prentice of California at , US, it a source of inspiration, a curiosity, Hall, 2003 dismisses many of them as ‘the basis or an irrelevance?  K E Drexler, Proc. Natl. Acad. Sci. USA, 1981, of Drexler’s mechanistic Newtonian ‘I had read it a long time before 78, 5275  K E Drexler, Engines of creation, Doubleday, models’ of nanotech. ‘Neither first manipulating atoms with the 1986 Feynman nor Drexler appreciated STM,’ says Eigler. ‘Within weeks of  R Feynman, in Miniaturization, ed. H H Gilbert, the ability of chemical synthesis to [doing that work], I went back to dig Reinhold, New York, 1961 respond to the nanotechnological up Feynman’s paper. I was more than  R Feynman, J. Microelectromech. Syst., 1993, 2, 4 age,’ says Fraser Stoddart. ‘Both saw ever impressed with how prescient  C Toumey, Eng. Sci., 2005, 1/2, 16 it as a given in the same billiard-ball Feynman’s thought were.’  G Whitesides and J C Love, Sci. Am., type mode that had met the needs of ‘I am not so inspired by the talk’s September 2001, 38 62 | Chemistry World | January 2009 www.chemistryworld.org