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Nanotechnology and space
Ralph C. Merkle
Principal Fellow, Zyvex
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Three historical trendsin manufacturing
• More diverse• More precise• Less expensive
Overview
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The limit of these trends: nanotechnology
• Fabricate most products consistent with physical law
• Get essentially every atom in the right place• Inexpensive (less than $1/kilogram)
http://www.zyvex.com/nano
Overview
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• Coal• Sand• Dirt, water & air
• Diamonds• Computer chips• Wood
Why it matters
Overview
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The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom.
Richard Feynman, 1959
http://www.zyvex.com/nanotech/feynman.html
Over forty years ago
There’s plenty of roomat the bottom
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The book that laid outthe technical argument for
molecular nanotechnology:
Nanosystemsby K. Eric Drexlerpublished in 1992
1980’s and 1990’s
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National Nanotechnology Initiative
• Announced by Clinton at Caltech• Interagency (AFOSR, ARO, BMDO,
DARPA, DOC, DOE, NASA, NIH, NIST, NSF, ONR, and NRL)
• FY 2001: $497 million
http://www.whitehouse.gov/WH/New/html/20000121_4.html
Today
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President Clinton on the NNI
“Imagine the possibilities: materials with ten times the strength of steel and only a small fraction of the weight -- shrinking all the information housed at the Library of Congress into a device the size of a sugar cube -- detecting cancerous tumors when they are only a few cells in size.”
Today
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• “Nanotechnology” has been applied broadly to almost any research where some dimension is less than a micron (1,000 nanometers) in size
• “Molecular nanotechnology” is focused specifically on inexpensively making most arrangements of atoms permitted by physical law
Definitions
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Possible arrangements of
atoms.
What we can make today(not to scale)
Definitions
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The goal: a healthy bite.
.
Definitions
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• Positional assembly (so molecular parts go where we want them to go)
• Self replication (for low cost)
Fundamental ideas
Nanotechnology
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H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999
Manipulation and bond formation by STM
Positional devices
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Saw-Wai Hla et al., Physical Review Letters 85, 2777-2780, September 25 2000
Manipulation and bond formation by STM
I I
Positional devices
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Theoretical proposal for amolecular robotic arm
Positional devices
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kTkb2
σ: mean positional error k: restoring forcekb: Boltzmann’s constantT: temperature
Classical uncertainty
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kTkb2
σ: 0.02 nm (0.2 Å) k: 10 N/mkb: 1.38 x 10-23 J/KT: 300 K
Classical uncertainty
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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.
Molecular tools
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A hydrogen abstraction tool
http://www.zyvex.com/nanotech/Habs/Habs.html
Molecular tools
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Some other molecular tools
Molecular tools
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A synthetic strategy for the synthesis of diamondoid structures
• Positional assembly (6 degrees of freedom)
• Highly reactive compounds (radicals, carbenes, etc)
• Inert environment (vacuum, noble gas) to eliminate side reactions
Molecular tools
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A hydrocarbon bearing
http://www.zyvex.com/nanotech/bearingProof.html
Molecular machines
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http://www.zyvex.com/nanotech/gearAndCasing.html
Molecular machines
A planetary gear
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The Von Neumann architecture
Computer Constructor
http://www.zyvex.com/nanotech/vonNeumann.html
Self replication
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Molecularcomputer
Molecularconstructor
Positional device Tip chemistry
Drexler’s architecurefor an assembler
Self replication
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Self replication
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);}
A C program that prints outan exact copy of itself
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Self replication
Print the following statement twice, the second time in quotes:
“Print the following statement twice, the second time in quotes:”
English translation:
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•Von Neumann'sconstructor 500,000
•Mycoplasma genitalia 1,160,140•Drexler's assembler 100,000,000•Human 6,400,000,000
http://www.zyvex.com/nanotech/selfRep.html
Complexity ofself replicating systems (bits)
Self replication
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An overview of self replicating systemsfor manufacturing
• Advanced Automation for Space Missions, edited by Robert Freitas and William Gilbreath NASA Conference Publication 2255, 1982
• A web page with an overview of replication: http://www.zyvex.com/nanotech/selfRep.html
Self replication
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• Nanotechnology is a manufacturing technology
• The impact depends on the product being manufactured
The impact of nanotechnology
The Vision
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• We’ll have more computing power in the volume of a sugar cube than the sum total of all the computer power that exists in the world today
• More than 1021 bits in the same volume• Almost a billion Pentiums in parallel
Powerful Computers
The Vision
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• Disease and ill health are caused largely by damage at the molecular and cellular level
• Today’s surgical tools are huge and imprecise in comparison
The Vision
http://www.foresight.org/Nanomedicine
Nanomedicine
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• In the future, we will have fleets of surgical tools that are molecular both in size and precision.
• We will also have computers much smaller than a single cell to guide those tools.
The Vision
Nanomedicine
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• Killing cancer cells, bacteria• Removing circulatory obstructions• Providing oxygen (artificial red blood cells)• Adjusting other metabolites
The Vision
Nanomedicine
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• By Robert Freitas, Zyvex Research Scientist
• Surveys medical applications of nanotechnology
• Volume I (of three) published in 1999
The Vision
Nanomedicine
http://www.foresight.org/Nanomedicine
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Human impact on the environment depends on
• Population
• Living standards
• Technology
The Vision
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Restoring the environmentwith nanotechnology
• Low cost hydroponics• Low cost solar power• Pollution free manufacturing
The Vision
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Military applications of molecular manufacturing have even greater potential than nuclear weapons to radically change the balance of power.
Admiral David E. Jeremiah, USN (Ret)
Former Vice Chairman, Joint Chiefs of Staff
November 9, 1995
http://www.zyvex.com/nanotech/nano4/jeremiahPaper.html
The Vision
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• New, inexpensive materials with a strength-to-weight ratio over 50 times that of steel
• Critical for aerospace: airplanes, rockets, satellites…
• Useful in cars, trucks, ships, ...
Lighter, stronger,smarter, less expensive
The Vision
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Space
• Launch vehicle structural mass could be reduced by a factor of 50
• Cost per kilogram for that structural mass could be under a dollar
• Which will reduce the cost to low earth orbit by a factor 1,000 or more
http://science.nas.nasa.gov/Groups/Nanotechnology/publications/1997/applications/
The Vision
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Greater function per unit weight
• Computers and sensors will weigh less per unit mass
• Greater functionality per pound, further reducing cost per function
http://science.nas.nasa.gov/Groups/Nanotechnology/publications/1997/applications/
The Vision
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Nanotechnology offers ... possibilities for health, wealth, and capabilities beyond most past imaginings.
K. Eric Drexler
Summation
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Born-Oppenheimer approximation• A carbon nucleus is more than 20,000 times as
massive as an electron• Assume the atoms (nuclei) are fixed and
unmoving, and then compute the electronic wave function
• If the positions of the atoms are given by r1, r2, .... rN then the energy of the system is:
E(r1, r2, .... rN)
• This is fundamental to molecular mechanics
Quantum uncertainty
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Ground state quantum uncertainty
σ2: positional variance
k: restoring force
m: mass of particle
ħ: Planck’s constant divided by 2π
km22
Quantum uncertainty
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• C-C spring constant: k~440 N/m• Typical C-C bond length: 0.154 nm• σ for C in single C-C bond: 0.004 nm• σ for electron (same k): 0.051 nm
Quantum uncertainty
A numerical example
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Basic assumptions
• Nuclei are point masses• Electrons are in the ground state• The energy of the system is fully
determined by the nuclear positions• Directly approximate the energy from the
nuclear positions, and we don’t even have to compute the electronic structure
Molecular mechanics
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Example: H2
Internuclear distance
En
erg
yMolecular mechanics
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Parameters• Internuclear distance for bonds
• Angle (as in H2O)
• Torsion (rotation about a bond, C2H6
• Internuclear distance for van der Waals • Spring constants for all of the above• More terms used in many models• Quite accurate in domain of
parameterization
Molecular mechanics