Merkle Suggests that in not too many decades we should be able to build products with almost every atom in the right place, inexpensively, and consistent with physical law Two main issues in nanotechnology: What will molecular manufacturing systems look like? What can we build today? Emphasizes the importance of the carbon structure of diamond for nanoscale devices One application of nanomachines would be in cancer therapy Proposes a molecular robotic arm to manipulate individual molecules Hydrogen abstraction tool Dimer deposition tool Hydrogen deposition tool Carbene insertion tool

Whitesides Looks to biology for examples of existing nanoscale machines and self-assembly Ribosomal RNA Chloroplasts Mitochondrion Flagellar motors Emphasizes the difficulty of constructing nanoscale machines with a molecular assembler Friction and sticking (or “stiction”) Power source Pincers or jaws must be smaller than the atoms to be manipulated Carbon atoms bond strongly to their neighbors It would be an incredible feat to outdesign evolution

Opinion With time, anything may be possible Modeling after nature may be faster Whitesides’ ideas seem a lot more practical given our current limitations Merkle’s ideas seem to require imagination and forward thinking Current experiments suggest that at least some of both of the scientists’ conceptions deserve consideration Until nanoscale structures become economically viable, not as much time and money will be spent on research