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Whither nanotechnology?. Ralph C. Merkle Distinguished Professor of Computing Georgia Tech College of Computing. Web pages. www.foresight.org. www.zyvex.com/nano. www.nano.gov. Health, wealth and atoms. Arranging atoms. Flexibility Precision Cost. Richard Feynman,1959.

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whither nanotechnology

Whither nanotechnology?

Ralph C. Merkle

Distinguished Professor of Computing

Georgia Tech College of Computing

slide2

Web pages

www.foresight.org

www.zyvex.com/nano

www.nano.gov

arranging atoms
Arranging atoms
  • Flexibility
  • Precision
  • Cost
slide5

Richard Feynman,1959

There’s plenty of room

at the bottom

1980 s 1990 s
1980’s, 1990’s

Experiment and theory

First STM

By Binnig and Rohrer

president clinton 2000
President Clinton, 2000

“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.”

The National Nanotechnology Initiative

slide8

The goal

Arrangements of atoms

.

Today

slide9

The goal

The goal

.

slide11

Experimental

H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999

slide13

Molecular mechanics

  • Manufacturing is about moving atoms
  • Molecular mechanics studies the motions of atoms
  • Molecular mechanics is based on the Born-Oppenheimer approximation
slide14

Born-Oppenheimer

The carbon nucleus has a mass over 20,000 times that of the electron

  • Moves slower
  • Positional uncertainty smaller
slide15

Born-Oppenheimer

  • Treat nuclei as point masses
  • Assume ground state electrons
  • Then 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
slide16

Hydrogen molecule: H2

Energy

Internuclear distance

slide20

Thermal noise

σ: mean positional error

k: restoring force

kb: Boltzmann’s constant

T: temperature

slide21

Thermal noise

σ: 0.02 nm (0.2 Å)

k: 10 N/m

kb: 1.38 x 10-23 J/K

T: 300 K

what to make
What to make

Diamond physical properties

Property Diamond’s value Comments

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

making diamond today
Making diamond today

Illustration courtesy of P1 Diamond Inc.

some journal publications
Some journal publications
  • Theoretical Analysis of Diamond Mechanosynthesis. Part I. Stability of C2 Mediated Growth of Nanocrystalline Diamond C(110) Surface, J. Comp. Theor. Nanosci. 1(March 2004), Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle. In press.
  • Theoretical Analysis of Diamond Mechanosynthesis. Part II. C2 Mediated Growth of Diamond C(110) Surface via Si/Ge-Triadamantane Dimer Placement Tools, J. Comp. Theor. Nanosci. 1(March 2004). David J. Mann, Jingping Peng, Robert A. Freitas Jr., Ralph C. Merkle, In press.
  • Theoretical analysis of a carbon-carbon dimer placement tool for diamond mechanosynthesis, Ralph C. Merkle and Robert A. Freitas Jr., J. Nanosci. Nanotechnol. 3 June 2003. (Abstract)
  • A proposed "metabolism" for a hydrocarbon assembler, Nanotechnology8 (1997) pages 149-162.
  • Theoretical studies of reactions on diamond surfaces, by S.P. Walch and R.C. Merkle, Nanotechnology9 (1998) pages 285-296.
  • Theoretical studies of a hydrogen abstraction tool for nanotechnology, by Charles Musgrave, Jason Perry, Ralph C. Merkle and William A. Goddard III; Nanotechnology 2 (1991) pages 187-195.
slide27

Self replication

A redwood tree

(sequoia sempervirens)

112 meters tall

Redwood National Park

http://www.zyvex.com/nanotech/selfRep.html

slide28

Self replication

The Von Neumann architecture

Universal

Computer

Universal

Constructor

http://www.zyvex.com/nanotech/vonNeumann.html

slide29

Self replication

Drexler’s proposal for an assembler

http://www.foresight.org/UTF/Unbound_LBW/chapt_6.html

self replication
Self replication

Kinematic Self-Replicating Machines (Landes Bioscience, 2004, in review).

Reviews the voluminous theoretical and experimental literature about physical self-replicating systems.

Freitas and Merkle

slide33

Replication

Manufacturing costsper kilogramwill be low

  • Today: potatoes, lumber, wheat, etc. are all about a dollar per kilogram.
  • Tomorrow: almost any product will be about a dollar per kilogram or less. (Design costs, licensing costs, etc. not included)
impact
Impact

The impact

of a new manufacturing technology

depends on what you make

impact1
Impact

Powerful Computers

  • 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
impact2
Impact

Lighter, stronger,

smarter, less expensive

  • 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, ...
slide37

Impact

  • 50x reduction of structural mass
  • Cost per kilogram under a dollar
  • Reducing cost to low earth orbit by 1,000 or more
  • http://science.nas.nasa.gov/Groups/
  • Nanotechnology/publications/1997/
  • applications/
impact3
Impact

Size of a robotic arm

~100 nanometers

8-bit computer

Mitochondrion

~1-2 by 0.1-0.5 microns

scale
Scale

Mitochondrion

Size of a robotic arm ~100 nanometers

8-bit computer

“Typical” cell: ~20 microns

survey of the field
Survey of the field

Nanomedicine

  • Surveys medical applications of nanotechnology
  • Volume I (of three) published in 1999
  • Robert Freitas, Zyvex

http://www.foresight.org/Nanomedicine

slide44

Global Security

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

slide45

Overview

Core molecular

manufacturing

capabilities

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Today

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

Products

slide46

How long?

  • Correct scientific answer: I don’t know
  • Trends in computer hardware suggestive
  • Beyond typical 3-5 year planning horizon
  • Depends on what we do
  • Babbage’s computer designed in 1830’s
research objectives
Research objectives

Goals

  • Mechanosynthesis

H abstraction, Carbene insertion, …

  • System design

assemblers, robotic arms, …

slide48
Nanotechnology offers ... possibilities for health, wealth, and capabilities beyond most past imaginings.

K. Eric Drexler

slide49

Quantum uncertainty

σ2: positional variance

k: restoring force

m: mass of particle

ħ: Planck’s constant divided by 2π

slide50

Quantum uncertainty

  • 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
slide51

Molecular mechanics

  • 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
slide52

Molecular mechanics

Limitations

  • Limited ability to deal with excited states
  • Tunneling (actually a consequence of the point-mass assumption)
  • Rapid nuclear movements reduce accuracy
  • Large changes in electronic structure caused by small changes in nuclear position reduce accuracy
slide54

Buckytubes

Fullerenes

SWNT

MWNT

Chirality

Buckminsterfullerenes

slide55

Buckytubes

What is “chirality?”

slide56

Molecular

constructor

Molecular

constructor

Molecular

constructor

Broadcast architecture

Macroscopic

computer

http://www.zyvex.com/nanotech/selfRep.html

nanopores
Nanopores

Illustration from Harvard Nanopore Group

millipede
Millipede

Illustration from IBM Zurich

slide59

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Minimal assembler

slide60

System designs

System

Sub-system

Sub-system

Sub-system

part

part

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slide61

System designs

Why don’t we have more system designs?

Development times are 10+ years

Planning horizons are usually 10- years

Research funding focused on “science”

FUD

slide62

What to do

  • Shorten development times
  • Identify intermediate targets
  • Gain support from groups with long planning horizons
  • Lengthen planning horizons
  • Reduce FUD by detailed design and analysis
slide63

Stiffness

E: Young’s modulus

k: transverse stiffness

r: radius

L: length

slide64

Stiffness

E: 1012 N/m2

k: 10 N/m

r: 8 nm

L: 100 nm

slide68

Space

  • SSTO (Single Stage To Orbit) vehicle
  • 3,000 kg total mass (including fuel)
  • 60 kilogram structural mass
  • 500 kg for four passengers with luggage, air, seating, etc.
  • Liquid oxygen, hydrogen
  • Cost: a few thousand dollars

K. Eric Drexler, Journal of the British Interplanetary Society,

V 45, No 10, pp 401-405 (1992).

Molecular manufacturing for space systems: an overview

an overview of replicating systems for manufacturing
An overview of replicating systemsfor manufacturing

Replication

  • 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
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