Transcript Long and medium term goals in molecular nanotechnology
Computational molecular nanotechnology
Ralph C. Merkle Xerox PARC www.merkle.com
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Remember this URL:
http://nano.xerox.com/nano
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Sixth Foresight Conference on Molecular Nanotechnology November 12-15, 1998 Santa Clara, California www.foresight.org/Conferences 3
The best technical introduction to molecular nanotechnology:
Nanosystems
by K. Eric Drexler, Wiley 1992 4
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 http://nano.xerox.com/nanotech/feynman.html
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Today’s manufacturing methods move atoms in great thundering statistical herds • Casting • Grinding • Welding • Sintering • Lithography 6
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 7
Possible arrangements of atoms .
What we can make today (not to scale) 8
The goal of molecular nanotechnology: a healthy bite.
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Molecular Manufacturing We don’t have molecular manufacturing today.
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We must develop fundamentally new capabilities.
What we can make today (not to scale) 10
Molecular Manufacturing What we can investigate experimentally .
What we can make today (not to scale) 11
Molecular Manufacturing What we can investigate theoretically .
What we can make today (not to scale) 12
“... 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 13
Today Overview of the development of molecular nanotechnology Products Products Core molecular manufacturing capabilities Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products Products
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 15
Two more fundamental ideas • • Self replication (for low cost) Programmable positional control (to make molecular parts go where we
want
them to go) 16
Complexity of self replicating systems (bits) Von Neumann's universal constructorabout 500,000 Internet worm (Robert Morris, Jr., 1988) 500,000 Mycoplasma capricolum E. Coli Drexler's assembler 1,600,000 9,278,442 100,000,000 Human NASA Lunar Manufacturing Facility 6,400,000,000 over 100,000,000,000 http://nano.xerox.com/nanotech/selfRep.html
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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
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English translation: Print the following statement twice, the second time in quotes: “Print the following statement twice, the second time in quotes:” 19
Von Neumann architecture for a self replicating system Universal Computer Universal Constructor 20
Drexler’s architecture for an assembler Molecular computer Molecular constructor Positional device Tip chemistry 21
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 http://nano.xerox.com/nanotech/selfRepNASA.html
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Diamond Physical Properties
Property Diamond’s value Comments
Chemical reactivity Hardness (kg/mm2) Thermal conductivity (W/cm-K) Tensile strength (pascals) Compressive strength (pascals) Band gap (ev) Resistivity (W-cm) Density (gm/cm3) Thermal Expansion Coeff (K-1) Refractive index Coeff. of Friction Extremely low 9000 20 3.5 x 10 9 (natural) 10 11 (natural) 5.5
10 16 (natural) 3.51
0.8 x 10-6 2.41 @ 590 nm 0.05 (dry) Source: Crystallume CBN: 4500 SiC: 4000 Ag: 4.3 Cu: 4.0
10 11 (theoretical) 5 x 10 11 (theoretical) Si: 1.1 GaAs: 1.4
SiO2: 0.5 x 10-6 Glass: 1.4 - 1.8
Teflon: 0.05
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A hydrocarbon bearing 24
A universal joint 25
A planetary gear 26
A differential gear 27
Neon pump 28
Fine motion controller 29
A proposal for a
molecular positional device
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Classical uncertainty 2
k b T k
σ: RMS positional error k: restoring force k b : Boltzmann’s constant T: temperature 31
A numerical example of classical uncertainty 2
k b T k
σ: 0.02 nm (0.2 Å) k: 10 N/m k b : 1.38 x 10 -23 T: 300 K J/K 32
Transverse stiffness of a solid cylinder of radius r and length L E: k: r: L: k 3
r
4
E
4
L
3 Young’s modulus transverse stiffness radius length 33
Transverse stiffness of a solid cylinder of radius r and length L E: k: r: L: k 3
r
4
E
4
L
3 10 12 N/m 2 10 N/m 8 nm 100 nm 34
Synthesis of diamond today:
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.
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A hydrogen abstraction tool http://nano.xerox.com/nanotech/Habs/Habs.html
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Some other molecular tools 37
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 38
A modest set of molecular tools should be sufficient to synthesize most stiff hydrocarbons.
http://nano.xerox.com/nanotech/ hydroCarbonMetabolism.html
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The hydrocarbon assembler • Simplifies molecular tools • Simplifies reaction pathways • Simplifies analysis • Simplifies feedstock • But a much narrower range of structures (stiff hydrocarbons) 40
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) http://nano.xerox.com/nanotech/hydroCarbonMetabolism.html
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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.
http://nano.xerox.com/nanotech/hydroCarbon Metabolism.html
(about two dozen reactions) 42
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 43
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 • Simple feedstock seconds) 44
The best way to predict the future is to invent it Alan Kay 45