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Nanotechnology

Ralph C. Merkle

Principal Fellow, Zyvex

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Health, wealth and atoms

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Arranging atoms

• Diversity• Precision• Cost

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Richard Feynman,1959

There’s plenty of roomat the bottom

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Eric Drexler, 1992

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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

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Today

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Arrangements of atoms

.

Today

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The goal

.

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Bearing

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Planetary gear

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Fine motion controller

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Robotic arm

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kTkb2

σ: mean positional error k: restoring forcekb: Boltzmann’s constantT: temperature

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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

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Making diamond today

• Carbon

• Hydrogen

• Add energy

• Grow diamond film.

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Hydrogen abstraction tool

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Some other molecular tools

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

Experimental work

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Self replication

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The Von Neumann architecture

Computer Constructor

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Molecularcomputer

Molecularconstructor

Positional device Tip chemistry

Drexler’s architecurefor an assembler

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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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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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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

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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

Complexity ofself replicating systems (bits)

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Exponential assembly

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The impact

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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

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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

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.

Nanomedicine

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Human impact on the environment depends on

• Population

• Living standards

• Technology

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Restoring the environmentwith nanotechnology

• Low cost hydroponics• Low cost solar power• Pollution free manufacturing

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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

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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

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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/

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

K. Eric Drexler

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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

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Pump

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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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A hydrocarbon bearing

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

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• Killing cancer cells, bacteria• Removing circulatory obstructions• Providing oxygen (artificial red blood cells)• Adjusting other metabolites

Nanomedicine

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• By Robert Freitas, Zyvex Research Scientist

• Surveys medical applications of nanotechnology

• Volume I (of three) published in 1999

Nanomedicine

http://www.foresight.org/Nanomedicine

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• Today, loss of cell function results in cellular deterioration:

function must be preserved

• With medical nanodevices, passive structures can be repaired. Cell function can be restored provided cell structure can be inferred:

structure must be preserved

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37º C 37º C

-196º C (77 Kelvins)

Freeze Restoreto health

Time

Tem

pera

ture

(some decades)

Cryonics

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• Select N subjects• Freeze them• Wait 100 years• See if the medical technology of 2100 can

indeed revive them

But what do we tell those who don’t expect to live long enough to see the results?

Clinical trials

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Join

the control group

or

the experimental group?

(www.alcor.org)

What to do?