分子ナノテクノロジーに関するドレクスラーとスモーリーの論争とは

分子ナノテクノロジーに関するドレクスラーとスモーリーの論争

出典: フリー百科事典『ウィキペディア（Wikipedia）』 (2021/09/07 15:05 UTC 版)

分子ナノテクノロジーに関するドレクスラーとスモーリーの論争（ぶんしナノテクノロジーにかんするドレクスラーとスモーリーのろんそう）では、分子ナノテクノロジーの概念的な基礎を打ち立てたK・エリック・ドレクスラーと、ナノ物質 C₆₀フラーレンを発見したことで1996年のノーベル化学賞を受賞したリチャード・スモーリーとの間で行われた、分子ナノテクノロジーに関する公開論争について述べる。その争点は、個々の原子や分子を操作することによって分子材料や分子デバイスを自律的に構築する分子マシン、すなわち分子アセンブラが実現可能かということであった。分子アセンブラはドレクスラーの創案による分子ナノテクノロジーの中核概念であったが、スモーリーはその存在が物理学の基本原理に反していると主張した。また両者は互いに、ナノテクノロジーに対する相手の考え方が一般のイメージを悪化させており、ナノテク研究への支援を途絶えさせかねないと非難し合った。

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引用文の原文

^ When a boy and a girl fall in love, it is often said that the chemistry between them is good. This common use of the word "chemistry" in human relations comes close to the subtlety of what actually happens in the more mundane coupling of molecules. In a chemical reaction between two 'consenting' molecules, bonds form between some of the atoms in what is usually a complex dance involving motion in multiple dimensions.... And if the chemistry is really, really good, the molecules that do react will all produce the exact product required.
^ Because the fingers of a manipulator arm must themselves be made out of atoms, they have a certain irreducible size. There just isn't enough room in the nanometer-size reaction region to accommodate all the fingers of all the manipulators necessary to have complete control of the chemistry.... [Also,] the atoms of the manipulator hands will adhere to the atom that is being moved. So it will often be impossible to release this minuscule building block in precisely the right spot. Both these problems are fundamental, and neither can be avoided. Self-replicating, mechanical nanobots are simply not possible in our world.
^ This ubiquitous biological molecular assembler suffers from neither the “fat finger” nor the “sticky finger” problem. If, as Smalley argues, both problems are “fundamental,” then why would they prevent the development of mechanical assemblers and not biological assemblers? If the class of molecular structures known as proteins can be synthesized using positional techniques, then why would we expect there to be no other classes of molecular structures that can be synthesized using positional techniques?
^ The impossibility of "Smalley fingers" has raised no concern in the research community because these fingers solve no problems and thus appear in no proposals. Your reliance on this straw-man attack might lead a thoughtful observer to suspect that no one has identified a valid criticism of my work. For this I should, perhaps, thank you.
^ Positional control naturally avoids most side reactions by preventing unwanted encounters between potential reactants. Transition-state theory indicates that, for suitably chosen reactants, positional control will enable synthetic steps at megahertz frequencies with the reliability of digital switching operations in a computer. The supporting analysis for this conclusion appears in "Nanosystems" and has withstood a decade of scientific scrutiny.
^ U.S. progress in molecular manufacturing has been impeded by the dangerous illusion that it is infeasible. I hope you will agree that the actual physical principles of molecular manufacturing are sound and quite unlike the various notions, many widespread in the press, that you have correctly rejected. 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.
^ 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. You still do not appear to understand the impact of my short piece in Scientific American. Much like you can't make a boy and a girl fall in love with each other simply by pushing them together, you cannot make precise chemistry occur as desired between two molecular objects with simple mechanical motion along a few degrees of freedom in the assembler-fixed frame of reference. Chemistry, like love, is more subtle than that.
^ You and people around you have scared our children. I don't expect you to stop, but 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.