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1 Computational molecular nanotechnology Ralph C. Merkle Xerox PARC

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Presentation on theme: "1 Computational molecular nanotechnology Ralph C. Merkle Xerox PARC"— Presentation transcript:

1 1 Computational molecular nanotechnology Ralph C. Merkle Xerox PARC

2 2 Remember this URL:

3 3 Sixth Foresight Conference on Molecular Nanotechnology November 12-15, 1998 Santa Clara, California

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

5 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 an attempt to violate any laws; it is something, in principle, that can be done; but in practice, it has not been done because we are too big. Richard Feynman, 1959

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

7 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)

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

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

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

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

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

13 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 14 Core molecular manufacturing capabilities Today Products Overview of the development of molecular nanotechnology

15 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 16 Two more fundamental ideas Self replication (for low cost)Self replication Programmable positional control (to make molecular parts go where we want them to go)Programmable positional control

17 17 Von Neumann's universal constructorabout 500,000 Internet worm (Robert Morris, Jr., 1988)500,000 Mycoplasma capricolum1,600,000 E. Coli9,278,442 Drexler's assembler100,000,000 Human6,400,000,000 NASA Lunar Manufacturing Facilityover 100,000,000,000 Complexity of self replicating systems (bits)

18 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:

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

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

21 21 Drexler’s architecture for an assembler Molecular computer Molecular constructor Positional deviceTip chemistry

22 22 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. Advanced Automation for Space Missions Proceedings of the 1980 NASA/ASEE Summer Study

23 23 Diamond Physical Properties PropertyDiamond’s valueComments Chemical reactivityExtremely low Hardness (kg/mm2)9000CBN: 4500 SiC: 4000 Thermal conductivity (W/cm-K)20Ag: 4.3 Cu: 4.0 Tensile strength (pascals)3.5 x 10 9 (natural)10 11 (theoretical) Compressive strength (pascals)10 11 (natural)5 x 10 11 (theoretical) Band gap (ev)5.5Si: 1.1 GaAs: 1.4 Resistivity (W-cm)10 16 (natural) Density (gm/cm3)3.51 Thermal Expansion Coeff (K-1)0.8 x 10-6SiO2: 0.5 x 10-6 Refractive index2.41 @ 590 nmGlass: 1.4 - 1.8 Coeff. of Friction0.05 (dry)Teflon: 0.05 Source: Crystallume

24 24 A hydrocarbon bearing

25 25 A universal joint

26 26 A planetary gear

27 27 A differential gear

28 28 Neon pump

29 29 Fine motion controller

30 30 A proposal for a molecular positional devicemolecular positional device

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

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

33 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 34 Transverse stiffness of a solid cylinder of radius r and length L E:10 12 N/m 2 k: 10 N/m r: 8 nm L:100 nm

35 35 Synthesis of diamond today: diamond CVD diamond CVD Carbon: methane (ethane, acetylene...) Hydrogen: H 2 Add energy, producing CH 3, H, etc. Growth of a diamond film. The right chemistry, but little control over the site of reactions or exactly what is synthesized.

36 36 A hydrogen abstraction tool

37 37 Some other molecular tools

38 38 A synthetic strategyA 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 39 A modest set of molecular tools should be sufficient to synthesize most stiff hydrocarbons. hydroCarbonMetabolism.html

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

41 41 Feedstock Acetone (solvent) Butadiyne (C 4 H 2, diacetylene: source of carbon and hydrogen) Neon (inert, provides internal pressure) “Vitamin” (transition metal catalyst such as platinum; silicon; tin)

42 42 Parts closure for 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. Metabolism.html (about two dozen reactions) Metabolism.html

43 43 We could design and model a 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 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 45 The best way to predict the future is to invent it Alan Kay

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