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【分享】Nanotechnology: past, present, and future【已搜索无重复】
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《nanotoday》上发表的Michael Pitkethly的评论，与虫友共享！ So where have we got to in answering the questions and challenges posed by both Richard Feynman and Vannevar Bush? The death of Arthur C. Clarke on March 19th this year generated considerable media coverage, not only because he was one of the best known and prolific science fiction writers, but also because of his visionary thoughts. He is credited with a wide range of predictions that are now reality, including satellite communications and ultrafast knowledge transfer that would effectively shrink the world even further than advances in transport had in the previous century. Many of these ideas were formulated in the late 1940s and early 1950s, reminding me that we are soon approaching a notable anniversary in the history of nanotechnology, namely the fiftieth anniversary of Richard Feynman's classic lecture, “There's plenty of room at the bottom” which was given in 1959 at Caltech. This lecture has been attributed with triggering the nanotechnology revolution and it is interesting to see how far we have come since then in realizing the vision that Richard Feynman had in 1959. Before I look at this it is worth remembering that Richard Feynman was talking in a world that was experiencing accelerating advances in science and technology. The Second World War had given science and technology a huge boost, albeit for military purposes, but inventions such as radar, computers, and the birth of micro-electronics have had a significant impact on the world today. Vannevar Bush, who was the Director of the Office of Scientific Research and Development in the US wrote a paper in 1945 reflecting on where scientists would direct their interests once the war was over. Many of his ruminations were about managing data but he recognized that increased miniaturization was key to progress and hypothesized that the Encyclopaedia Britannica could be reduced to the volume of a matchbox using microphotography, a significant reduction from 24 volumes and six feet of shelf space. He also recognized that miniaturizing thermionic values, essential to computers of the day, would enable the speed of counting electrical impulses to increase from 100 000 a second by a factor of 100 or more. Fourteen years later Feynman was talking about putting the Encyclopaedia Britannica on the head of a pin. He also opened up the idea of portable and rewritable mass storage, high intensity light sources, electronics not based on electron transfer, small mechanical machines and atomic manipulation. However, Feynman astutely recognized that there are two very important aspects to increased miniaturization, which are key to progress; the ability to make things smaller and the ability to probe and see what has been made. The challenges that Feynman made addressed how to store more information, how to manufacture nanoscale mechanical devices and then how to mass produce them. Feynman made no claims as to how these might be achieved but based on his understanding of physics he could see that theoretically all these were feasible. So where have we got to in answering the questions and challenges posed by both Feynman and Bush? Computing power has wildly exceeded expectations with portable rewritable storage devices having >1Tbyte capacity now common and even solid state memory is now at the 80Gbyte level and increasing. Computer processing power is measured in Tflops with chip speeds moving towards 4GHz. These have enabled the internet and mass information to flow around the world. High intensity light sources – lasers – are now common although Feynman was unsure about the economic need for them, microscopy has developed to the extent that atomic resolution is unexciting and atomic force microscopes and their derivatives have made true manipulation of individual atoms a reality. The miniaturization of machines has not reached the levels that these other areas have, although mass production of microelectromechanical systems with nanoscale features is common place. This has opened up the prospect of massively parallel processing techniques. Simple biological machines have been demonstrated in the lab but these are many years away from anything approaching commercialization. Spintronics is developing rapidly and molecular computing is not the remote prospect it once was. There are also a significant number of new discoveries that have opened up even more potential than Feynman envisaged, such as carbon nanotubes and conducting polymers. So what about the next set of challenges and visions? One consequence of the advances in information technology and computing is that communications are now so rapid on a global scale that predictions have become relatively common place, with significantly more emphasis on tackling big issues and global problems. The United Nations have produced their eight Millennium Development Goals, five of which require significant advances in technology. Looking at the list it becomes apparent that these are not going to be achieved rapidly, but if significant progress is to be made towards achieving these goals, nanotechnology will have to play a significant role. In fact, many will not be achievable without it. To the scientist, the details of how this is done will be impressive but to the general public it will be incomprehensible, which brings me back to Arthur C. Clarke who recognized the impact nanotechnology could have on society, and his Third Law – “Any sufficiently advanced technology is indistinguishable from magic.” Something for all nanotechnologists to remember. |
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