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Drexler–Smalley debate on molecular nanotechnology

24 points by luu 11y ago

williamjennings 11y ago
Smalley was obviously right because Drexler thought that nanotechnology would eventually become something like mechanical engineering. That does not work, because quantum mechanics are the default nanoscale rules. However, Drexler was able to contradict himself enough to make an interesting point about molecular assembly in ribosomes; it just does not have the same atomic precision as peptide synthesis. Therefore, nanotechnology is now firmly in the discipline of chemical engineering. In that article, I can find one quote from Smalley which was certainly untrue at the time: "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." Shellfish nucleate crystals of silicon, and bacteria nucleate magnetic nanoparticles of iron. That much was obvious to geologists during Smalley's lifetime, but one could still construe chemical skepticism. May the victor of the debate rest in peace; and let K. Eric Drexler correct himself as much as he wants.
- murbard2 11y ago
  > Smalley was obviously right because Drexler thought that nanotechnology would eventually become something like mechanical engineering. That does not work, because quantum mechanics are the default nanoscale rules. Non sequitur. First off, quantum mechanics apply at all scales, not just the nanoscale. The question is whether one can model these those machines using classical models instead of the much more computationally intensive quantum mechanical models. Part of the reason the proposals focus on diamondoid structures is that the rigidity of the bonds greatly limits the degrees of freedoms, making molecular mechanics approach accurate enough to model various designs.
  - williamjennings 11y ago
    Talk about Non sequitur! It does not seem like you understand my use of the word 'default'; because scales are nested, the nanoscale is everywhere. One can design molecular machines using classical models; but those models are chemical rather than mechanical. The diamondoid structures are the fruit of carbon research; and the molecular mechanics has gotten much computationally cheaper, especially with regards to biomolecules. The motivation for using carbon is the modularity, not rigidity; albeit biomolecules are even more modular than carbon alone.
    - murbard2 11y ago
      The rigidity buys you a lot. It's not just easier modelling, it's also higher reliability. If your bond is rigid, you don't have to worry too much about heat causing errors in the synthesis.
      - williamjennings 11y ago
        The rigidity is the expensive part. Modeling has gotten easier with parallel distributed computing. Reliability is of qualia that I would only attribute to platinum group metals. If heat causes errors in an organic synthesis, then that reaction mechanism is not selective enough for the desired purpose. The flexible bonds in biopolymers serve as counterpoint to the notion that bond rigidity is essential to stochastic nanotechnology. On the contrary, self-assembly requires some bond flexibility.
        murbard2 11y ago
        Rigidity helps you for the same reason using a jointed arm is easier than controlling a tentacle. Limiting the number of degrees of freedom can make things a whole lot easier. Yes, there are interesting designs with biopolymers, but they probably cannot get you the type of atomically precise manufacturing that you need for most "cool" MNT applications.
        williamjennings 11y ago
mannykannot 11y ago
There is something ironic in Drexler's invocation of biology to defend the plausibility of his vision, as it also suggests that biochemical and biologically-inspired methods might well be more appropriate than his approach of attempting to scale down human-scale machinery to a size where molecular forces and quantum effects are significant. So far, it is the former, and only the former, that has demonstrated progress. Drexler's approach seems akin to building a computer by using micro-fabrication techniques to create a network of tiny relays.
- deleted 11y ago
  [deleted]
- vilhelm_s 11y ago
  A computer made of nanoscale mechanical latches, made using nano-fabricators, was in fact one of the examples Drexler proposed. Supposedly it would perform better than transistor-based ones. [http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html] But isn't current computers an example of microscale fabrication that worked without being biochemical or biologically-inspired? They are made using optical etching, completely different from anything biology does.
  - mannykannot 11y ago
    > But isn't current computers an example of microscale fabrication that worked without being biochemical or biologically-inspired? They are made using optical etching, completely different from anything biology does. Yes, and as such, this is another example suggesting that the road to nano-technology is not through the shrinking of macro-scale machinery. This may be moot, however, as this is not a self-replicating technology, unlike either Drexler's hypothetical or biology's actual molecular assemblers. Drexler's claims about the feasibility, let alone the performance, of his proposed computer strike me as highly speculative and sometimes self-serving (see, for example, the section on thermodynamic reversibility.) Furthermore, computer performance has made huge advances since the devices (Z80, Motorola 68000) he was comparing to.
- hga 11y ago

24 points by luu 11y ago

Smalley was obviously right because Drexler thought that nanotechnology would eventually become something like mechanical engineering. That does not work, because quantum mechanics are the default nanoscale rules. However, Drexler was able to contradict himself enough to make an interesting point about molecular assembly in ribosomes; it just does not have the same atomic precision as peptide synthesis. Therefore, nanotechnology is now firmly in the discipline of chemical engineering. In that article, I can find one quote from Smalley which was certainly untrue at the time: "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." Shellfish nucleate crystals of silicon, and bacteria nucleate magnetic nanoparticles of iron. That much was obvious to geologists during Smalley's lifetime, but one could still construe chemical skepticism. May the victor of the debate rest in peace; and let K. Eric Drexler correct himself as much as he wants.

murbard2 11y ago
> Smalley was obviously right because Drexler thought that nanotechnology would eventually become something like mechanical engineering. That does not work, because quantum mechanics are the default nanoscale rules. Non sequitur. First off, quantum mechanics apply at all scales, not just the nanoscale. The question is whether one can model these those machines using classical models instead of the much more computationally intensive quantum mechanical models. Part of the reason the proposals focus on diamondoid structures is that the rigidity of the bonds greatly limits the degrees of freedoms, making molecular mechanics approach accurate enough to model various designs.
- williamjennings 11y ago
  Talk about Non sequitur! It does not seem like you understand my use of the word 'default'; because scales are nested, the nanoscale is everywhere. One can design molecular machines using classical models; but those models are chemical rather than mechanical. The diamondoid structures are the fruit of carbon research; and the molecular mechanics has gotten much computationally cheaper, especially with regards to biomolecules. The motivation for using carbon is the modularity, not rigidity; albeit biomolecules are even more modular than carbon alone.
  - murbard2 11y ago
    The rigidity buys you a lot. It's not just easier modelling, it's also higher reliability. If your bond is rigid, you don't have to worry too much about heat causing errors in the synthesis.
    - williamjennings 11y ago
      The rigidity is the expensive part. Modeling has gotten easier with parallel distributed computing. Reliability is of qualia that I would only attribute to platinum group metals. If heat causes errors in an organic synthesis, then that reaction mechanism is not selective enough for the desired purpose. The flexible bonds in biopolymers serve as counterpoint to the notion that bond rigidity is essential to stochastic nanotechnology. On the contrary, self-assembly requires some bond flexibility.
      - murbard2 11y ago
        Rigidity helps you for the same reason using a jointed arm is easier than controlling a tentacle. Limiting the number of degrees of freedom can make things a whole lot easier. Yes, there are interesting designs with biopolymers, but they probably cannot get you the type of atomically precise manufacturing that you need for most "cool" MNT applications.
        williamjennings 11y ago

mannykannot 11y ago

There is something ironic in Drexler's invocation of biology to defend the plausibility of his vision, as it also suggests that biochemical and biologically-inspired methods might well be more appropriate than his approach of attempting to scale down human-scale machinery to a size where molecular forces and quantum effects are significant. So far, it is the former, and only the former, that has demonstrated progress. Drexler's approach seems akin to building a computer by using micro-fabrication techniques to create a network of tiny relays.

deleted 11y ago
[deleted]
vilhelm_s 11y ago
A computer made of nanoscale mechanical latches, made using nano-fabricators, was in fact one of the examples Drexler proposed. Supposedly it would perform better than transistor-based ones. [http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html http://www.halcyon.com/nanojbl/NanoConProc/nanocon2.html] But isn't current computers an example of microscale fabrication that worked without being biochemical or biologically-inspired? They are made using optical etching, completely different from anything biology does.
- mannykannot 11y ago
  > But isn't current computers an example of microscale fabrication that worked without being biochemical or biologically-inspired? They are made using optical etching, completely different from anything biology does. Yes, and as such, this is another example suggesting that the road to nano-technology is not through the shrinking of macro-scale machinery. This may be moot, however, as this is not a self-replicating technology, unlike either Drexler's hypothetical or biology's actual molecular assemblers. Drexler's claims about the feasibility, let alone the performance, of his proposed computer strike me as highly speculative and sometimes self-serving (see, for example, the section on thermodynamic reversibility.) Furthermore, computer performance has made huge advances since the devices (Z80, Motorola 68000) he was comparing to.
hga 11y ago