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The following is a very brief summary of the contents of K. Eric Drexler's foundational work on molecular nanotechnology, Nanosystems: Molecular Machinery, Manufacturing, and Computation.
Chapters 1, 2, and the Glossary are posted
in full at
Drexler's website, and are linked from this page.
Molecular manufacturing should be able to build mechanical systems with amazing performance at the nanoscale. This book will explain how this works, building on basic physics and chemistry. These systems can efficiently build products that are large, atomically precise, diamond-strong, include very powerful computers (ten million MIPS per milliwatt) and motors (a megawatt per cubic millimeter).
A lot of nanoscale properties can be predicted directly from physics. Electromagnetism doesn't work but electrostatics works well. Things get floppy, but not too floppy. Cooling small systems is easy. Very small things move a lot faster.
Chapter 3: Potential Energy Surfaces
Chemical reactions are more or less predictable. Mechanical properties can be derived from chemical bond properties. Surfaces are sticky and squishy.
Chapter 4: Molecular Dynamics
Atomic systems wiggle and shift. Different configurations/positions of the systems have different energies. A configuration that requires high energy (relative to thermal noise) can form a barrier between states; between barriers (in potential wells), the system can take any configuration and the probability of each configuration can be calculated.
Chapter 5: Positional Uncertainty
You can make engineering estimates of the positional uncertainty of things like nanometer-scale rods, springs, and gas-filled pistons, taking into account the combined effects of quantum mechanics and thermal noise. For most purposes, positional uncertainty is a simple function of temperature and stiffness.
Chapter 6: Transitions, Errors, and Damage
If you know the barrier heights between potential wells, the probability of crossing between them (making a reaction, or a mistake) can be calculated as a function of temperature and time. Placement errors can be calculated. Strong covalent bonds don't usually break at room temperature in the dark. In a well-designed system, background radiation damage will be most significant—several percent per year per cubic micron.
Chapter 7: Energy Dissipation
There are lots of ways for energy to be thermalized. These can be calculated. They cause drag in bearings and other moving parts, and the energy dissipated is usually proportional to the speed of the system.
Chapter 8: Mechanosynthesis
Mechanosynthesis has many advantages over solution-phase synthesis, and should have as broad a range of products. It can apply positional control to select between similar reaction sites and keep reactive molecules isolated. There are quite a few stiff reactive molecules suitable for vacuum-phase mechanochemistry. Several diamond-forming reactions are proposed. Error rates can be held below 10-15 for useful reactions.
Chapter 9: Nanoscale Structural Components
Even small diamondoid rods and housings can embody useful stiffness and well-defined surface. Shape and size can be controlled with high precision by substituting atoms, and this provides an enormous number of options for part design.
Chapter 10: Mobile Interfaces and Moving Parts
Atomic-scale moving parts are bumpy, but thermal noise can push past these bumps (low energy barriers), implying zero static friction at ordinary temperatures. Dynamic friction is still an issue (Chapter 7). Atoms can make good gear teeth. Molecular models are shown for mechanisms including a planetary gear. Ratchets, irregular sliding surfaces, adhesive interfaces, and other useful structures are discussed.
Chapter 11: Intermediate Subsystems
Discusses measurement devices, harmonic and toroidal drives, fluids, seals, pumps, fractal cooling (extracting 105 W from 1 cm3), and electrostatics (1017 W/m3 power density at >99% efficiency).
Chapter 12: Nanomechanical Computational Systems
Discusses mechanical logic gates, registers, logic arrays, reversible logic, and long-range data transmission. Calculations imply the feasibility of 106-interlock 1-GHz CPUs (comparable to 2000 microprocessors) occupying <1 cubic micron and using 60 nW. (This is a lower bound, and can presumably be improved.)
Chapter 13: Molecular Sorting, Processing, and Assembly
Describes sorting rotors to import molecules and purify the input stream; conveyors; binding sites; molecular mills for repeated mechanochemistry (and power generation); conditional encounter mechanisms; a robot arm stiff enough to do mechanochemistry at room temperature with a 100-nm range.
Chapter 14: Molecular Manufacturing systems
Covers tabletop factory design issues: joining intermediate-scale blocks; factory system layout; factory shells and product delivery; redundancy; productivity calculations (can make its weight in an hour). This will be much better than conventional manufacturing on many counts. Discussion of shape-description languages and design compilers.
Chapter 15: Macromolecular Engineering
Cells implement many mechanisms: struts, bearings, clamps, actuators/motors, etc. Biopolymer design is easier than the protein folding problem. Solution synthesis can bootstrap dry-MNT systems. Using SPMs for fabrication and imaging.
Chapter 16: Paths to Molecular Manufacturing
There are many paths; backward chaining can be used to find a likely one. Simple actuators and manipulators are described, along with molecule handling, solution-phase intermediate systems, and ways to reduce development time.
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