Computational molecular nanotechnology

1. Computational molecular nanotechnology Ralph C. Merkle Xerox PARC www.merkle.com

2. Remember this URL:http://nano.xerox.com/nano

3. Sixth Foresight Conference on Molecular NanotechnologyNovember 12-15, 1998Santa Clara, Californiawww.foresight.org/Conferences

4. The best technical introduction to molecular nanotechnology:Nanosystems by K. Eric Drexler,Wiley 1992

5. The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not anattempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are toobig. Richard Feynman, 1959 http://nano.xerox.com/nanotech/feynman.html

6. Today’s manufacturing methods move atoms in great thundering statistical herds • Casting • Grinding • Welding • Sintering • Lithography

7. Molecular nanotechnology(a.k.a. molecular manufacturing) • Fabricate most structures that are specified with molecular detail and which are consistent with physical law • Get essentially every atom in the right place • Inexpensive manufacturing costs (~10-50 cents/kilogram) http://nano.xerox.com/nano

8. Possible arrangements of atoms What we can make today (not to scale) .

9. The goal of molecular nanotechnology: a healthy bite. .

10. Molecular Manufacturing We don’t have molecular manufacturing today. We must develop fundamentally new capabilities. . What we can make today (not to scale)

11. Molecular Manufacturing What we can investigate experimentally . What we can make today (not to scale)

12. Molecular Manufacturing What we can investigate theoretically . What we can make today (not to scale)

13. “... the innovator has for enemies all those who have done well under the old conditions, and lukewarm defenders in those who may do well under the new. This coolness arises ... from the incredulity of men, who do not readily believe in new things until they have had a long experience of them.” The Prince, by Niccolo Machiavelli

14. Products Products Core molecular manufacturing capabilities Products Products Products Products Products Products Products Products Products Products Products Today Products Products Products Products Products Overview of the development of molecular nanotechnology Products Products Products Products Products Products Products Products

15. Working backwards from the goal as well as forwards from the start • Backward chaining (Eric Drexler) • Horizon mission methodology (John Anderson) • Retrosynthetic analysis (Elias J. Corey) • Shortest path and other search algorithms in computer science • “Meet in the middle” attacks in cryptography

16. Two more fundamental ideas • Self replication (for low cost) • Programmable positional control (to make molecular parts go where we want them to go)

17. Complexity of self replicating systems (bits) • Von Neumann's universal constructor about 500,000 • Internet worm (Robert Morris, Jr., 1988) 500,000 • Mycoplasma capricolum 1,600,000 • E. Coli 9,278,442 • Drexler's assembler 100,000,000 • Human 6,400,000,000 • NASA Lunar • Manufacturing Facility over 100,000,000,000 http://nano.xerox.com/nanotech/selfRep.html

18. A C program that prints out an exact copy of itself main(){char q=34, n=10,*a="main() {char q=34,n=10,*a=%c%s%c; printf(a,q,a,q,n);}%c";printf(a,q,a,q,n);} For more information, see the Recursion Theorem: http://nano.xerox.com/nanotech/selfRep.html

19. English translation: Print the following statement twice, the second time in quotes: “Print the following statement twice, the second time in quotes:”

20. Von Neumann architecture for a self replicating system Universal Computer Universal Constructor

21. Drexler’s architecture for an assembler Molecular computer Molecular constructor Positional device Tip chemistry

22. Advanced Automation for Space Missions Proceedings of the 1980 NASA/ASEE Summer Study The theoretical concept of machine duplication is well developed. There are several alternative strategies by which machine self-replication can be carried out in a practical engineering setting. http://nano.xerox.com/nanotech/selfRepNASA.html

23. Diamond Physical Properties PropertyDiamond’s valueComments Chemical reactivity Extremely low Hardness (kg/mm2) 9000 CBN: 4500 SiC: 4000 Thermal conductivity (W/cm-K) 20 Ag: 4.3 Cu: 4.0 Tensile strength (pascals) 3.5 x 109 (natural) 1011 (theoretical) Compressive strength (pascals) 1011 (natural) 5 x 1011 (theoretical) Band gap (ev) 5.5 Si: 1.1 GaAs: 1.4 Resistivity (W-cm) 1016 (natural) Density (gm/cm3) 3.51 Thermal Expansion Coeff (K-1) 0.8 x 10-6 SiO2: 0.5 x 10-6 Refractive index 2.41 @ 590 nm Glass: 1.4 - 1.8 Coeff. of Friction 0.05 (dry) Teflon: 0.05 Source: Crystallume

24. A hydrocarbon bearing

25. A universal joint

26. A planetary gear

27. A differential gear

28. Neon pump

29. Fine motion controller

30. A proposal for a molecular positional device

31. Classical uncertainty σ: RMS positional error k: restoring force kb: Boltzmann’s constant T: temperature

32. A numerical example of classical uncertainty σ: 0.02 nm (0.2 Å) k: 10 N/m kb: 1.38 x 10-23 J/K T: 300 K

33. Transverse stiffness of a solid cylinder of radius r and length L E: Young’s modulus k: transverse stiffness r: radius L: length

34. Transverse stiffness of a solid cylinder of radius r and length L E: 1012 N/m2 k: 10 N/m r: 8 nm L: 100 nm

35. Synthesis of diamond today:diamond CVD • Carbon: methane (ethane, acetylene...) • Hydrogen: H2 • Add energy, producing CH3, H, etc. • Growth of a diamond film. The right chemistry, but little control over the site of reactions or exactly what is synthesized.

36. A hydrogen abstraction tool http://nano.xerox.com/nanotech/Habs/Habs.html

37. Some other molecular tools

38. A synthetic strategy for the synthesis of diamondoid structures • Positional control (6 degrees of freedom) • Highly reactive compounds (radicals, carbenes, etc) • Inert environment (vacuum, noble gas) to eliminate side reactions

39. A modest set of molecular tools should be sufficient to synthesize most stiff hydrocarbons. http://nano.xerox.com/nanotech/ hydroCarbonMetabolism.html

40. The hydrocarbon assembler • Simplifies molecular tools • Simplifies reaction pathways • Simplifies analysis • Simplifies feedstock • But a much narrower range of structures (stiff hydrocarbons)

41. Feedstock • Acetone (solvent) • Butadiyne (C4H2, diacetylene: source of carbon and hydrogen) • Neon (inert, provides internal pressure) • “Vitamin” (transition metal catalyst such as platinum; silicon; tin) http://nano.xerox.com/nanotech/hydroCarbonMetabolism.html

42. Parts closurefor molecular tools • A set of synthetic pathways that permits construction of all molecular tools from the feedstock. • Can’t “go downhill,” must be able to make a new complete set of molecular tools while preserving the original set. • http://nano.xerox.com/nanotech/hydroCarbonMetabolism.html (about two dozen reactions)

43. We could design and modela simple hydrocarbon assembler today • Speed the development of the technology • Allow rapid and low cost exploration of design alternatives • Provide a clearer target for experimental work • Give us a clearer picture of what this technology will be able to do

44. Critical assumptions in the design of a diamondoid assembler • Must synthesize diamond • Highly reactive tools • Inert environment • Positional control • Low error rate (10-12) • Rapid unit operations (~10-6 seconds) • Simple feedstock

45. The best way to predict the future is to invent it Alan Kay