This link has been bookmarked by 13 people . It was first bookmarked on 18 Jul 2006, by Martin Colwell.
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28 Jan 15
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Are "molecular assemblers"--devices capable of positioning atoms and molecules for precisely defined reactions in almost any environment--physically possible?
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he urged society to thoroughly examine the implications of the technology and develop mechanisms to ensure its benevolent application.
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For the past decade, he has been a leading proponent of a coordinated national research effort in nanoscale science and technology.
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Smalley outlined his scientific objections to the idea of molecular assemblers, specifically what he called the "fat fingers problem" and the "sticky fingers problem."
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He believes that speculation about the potential dangers of nanotechnology threatens public support for it.
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I have attempted to minimize confusion by relabeling the longer term goal "molecular manufacturing."
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The task of positioning reactive molecules simply doesn't require them.
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It rests on well-established physical principles.
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lead a thoughtful observer to suspect that no one has identified a valid criticism of my work.
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your attempt to calm the public through false claims of impossibility will inevitably fail,
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as observed that "when a scientist says something is possible, they're probably underestimating how long it will take. But if they say it's impossible, they're probably wrong." The scientist quoted is, of course, Richard Smalley.
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You have my respect and thanks.
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"Smalley fingers" is an impossibility
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one atom at a time applies also to placing larger, more complex building blocks
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"like enzymes and ribosomes." Fine, then I agree that at least now it can do precise chemistry.
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How does the nanobot know when the enzyme is damaged and needs to be replaced? How does the nanobot do error detection and error correction?
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but it can't make a crystal of silicon, or steel, or copper, or aluminum, or titanium, or virtually any of the key materials on which modern technology is built.
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I can only guess that you imagine it is possible to make a molecular entity that has the superb, selective chemical-construction ability of an enzyme without the necessity of liquid water.
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then there is a long list of vulnerabilities and limitations to what it can do.
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'm glad you found my early work stimulating, and applaud your goal of debunking nonsense in nanotechnology.
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Feynman's vision of nanotechnology is fundamentally mechanical, not biological. Molecular manufacturing concepts follow this lead.
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The technical questions you raise reach beyond chemistry to systems engineering.
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The smallest devices position molecular parts to assemble structures through mechanosynthesis--'machine-phase' chemistry.
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In machine-phase chemistry, conveyors and positioners (not solvents and thermal motion) bring reactants together.
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sitional control naturally avoids most side reactions by preventing unwanted encounters between potential reactants.
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Direct positional control of reactants is both achievable and revolutionary; talk of additional, impossible control has been a distraction.
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Nanofactories based on mechanosynthesis thus will be powerful enablers for a wide range of other nanotechnologies.
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Thus, multiple areas of current research (in computational chemistry, organic synthesis, protein engineering, supramolecular chemistry, and scanning-probe manipulation of atoms and molecules) constitute progress toward molecular manufacturing.
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Like any major engineering goal, it will require the design and analysis of desired systems, and a coordinated effort to develop parts that work together as an integrated whole.
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The resulting abilities will be so powerful that, in a competitive world, failure to develop molecular manufacturing would be equivalent to unilateral disarmament.
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I invite you to join me and others in the call to augment today's nanoscale research with a systems engineering effort aimed at achieving the grand vision articulated by Richard Feynman.
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I see you have now walked out of the room where I had led you to talk about real chemistry, and you are now back in your mechanical world. I am sorry we have ended up like this. For a moment I thought we were making progress.
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But in all of your writings, I have never seen a convincing argument that this list of conditions and synthetic targets that will actually work reliably with mechanosynthesis can be anything but a very, very short list.
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You need something very much like an enzyme.
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of your robotic assembler arm you need an enzymelike tool. That is why I led you in my reply into a room to talk about real chemistry with real enzymes, trying to get you to realize the limitations of this approach.
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You are still in a pretend world where atoms go where you want because your computer program directs them to go there
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I consider that your failure to provide a working strategy indicates that you implicitly concur--even as you explicitly deny--that the idea cannot work.
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I did what I could to allay their fears, but there is no question that many of these youngsters have been told a bedtime story that is deeply troubling.
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t I hope others in the chemical community will join with me in turning on the light, and showing our children that, while our future in the real world will be challenging and there are real risks, there will be no such monster as the self-replicating mechanical nanobot of your dreams.
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13 Nov 13
Neal AggarwalDrexler and Smalley make the case for and against 'molecular assemblers'
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14 Nov 11
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13 Aug 10
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He believes that speculation about the potential dangers of nanotechnology threatens public support for it.
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Notions about the darker side of nanotechnology have rapidly entered the public consciousness. Two notable examples were an April 2000 essay in Wired magazine titled "Why the Future Doesn't Need Us" by Sun Microsystems cofounder and chief scientist Bill Joy and the 2002 novel "Prey" by Michael Crichton.
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As you know, I introduced the term "nanotechnology" in the mid-1980s to describe advanced capabilities based on molecular assemblers: proposed devices able to guide chemical reactions by positioning reactive molecules with atomic precision
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This proposal has been defended successfully again and again, in journal articles, in my MIT doctoral thesis [the basis of "Nanosystems: Molecular Machinery, Manufacturing, and Computation," John Wiley & Sons (1992)]. And before scientific audiences around the world. It rests on well-established physical principles.
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However, I have from the beginning argued that the potential for abuse of advanced nanotechnologies makes vigorous research by the U.S. and its allies imperative.
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I hope you will further agree that the same argument I used to show the infeasibility of tiny fingers placing one atom at a time applies also to placing larger, more complex building blocks.
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But where does the enzyme or ribosome entity come from in your vision of a self-replicating nanobot?
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Biology is wonderous in the vast diversity of what it can build, but it can't make a crystal of silicon, or steel, or copper, or aluminum, or titanium, or virtually any of the key materials on which modern technology is built. Without such materials, how is this self-replicating nanobot ever going to make a radio, or a laser, or an ultrafast memory, or virtually any other key component of modern technological society that isn't made of rock, wood, flesh, and bone?
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The central problem I see with the nanobot self-assembler then is primarily chemistry. If the nanobot is restricted to be a water-based life-form, since this is the only way its molecular assembly tools will work, then there is a long list of vulnerabilities and limitations to what it can do. If it is a non-water-based life-form, then there is a vast area of chemistry that has eluded us for centuries.
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In light of the nature of your questions and of misperceptions frequently articulated in the press, I should first sketch the fundamental concepts of molecular manufacturing. These spring from Richard Feynman's famous 1959 talk, "There's Plenty of Room at the Bottom," which envisioned using productive machinery--factories--to build smaller factories, leading ultimately to nanomachines building atomically precise products.
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These issues are explored in technical depth in my book "Nanosystems: Molecular Machinery, Manufacturing, and Computation" (Wiley/Interscience, 1992), which describes the physical basis for desktop-scale nanofactories able to build atomically precise macroscopic products, including more nanofactories.
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Synthetic reactions and molecular machinery of the sort required for nanofactories have parallels in known systems, and have been explored using computational chemistry by Georgia Institute of Technology professor Ralph Merkle and others
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Why does this goal matter? Elementary physical principles indicate that molecular manufacturing will be enormously productive. Scaling down moving parts by a factor of a million multiplies their frequency of operation--and in a factory, their productivity per unit mass--by the same factor. Building with atomic precision will dramatically extend the range of potential products and decrease environmental impact as well. The resulting abilities will be so powerful that, in a competitive world, failure to develop molecular manufacturing would be equivalent to unilateral disarmament.
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14 Nov 08
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11 Dec 06
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24 Dec 05
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19 May 05
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In this C&EN exclusive "Point-Counterpoint," two of nanotechnology's biggest advocates square off on a fundamental question that will dramatically affect the future development of this field. Are "molecular assemblers"--devices capable of positioning atoms and molecules for precisely defined reactions in almost any environment--physically possible?
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