Transcript Nanotechnology: basic concepts and potential applications Ralph C. Merkle, Ph.D. Principal Fellow Slides on web The overheads (in PowerPoint) are available on the web at: http://www.zyvex.com/nanotech/talks/ppt/ Berkeley.

Nanotechnology:
basic concepts and potential applications
Ralph C. Merkle, Ph.D.
Principal Fellow
2
Slides on web
The overheads (in PowerPoint) are
available on the web at:
http://www.zyvex.com/nanotech/talks/ppt/
Berkeley 010505.ppt
3
Foresight
Ninth Foresight Conference
on Molecular Nanotechnology
November 9-11, 2001
Santa Clara, California
Introductory tutorial November 8
www.foresight.org/Conferences/MNT9/
4
Foresight
www.nanodot.org
www.foresight.org/SrAssoc/
Gatherings
5
Health, wealth and atoms
6
Arranging atoms
• Diversity
• Precision
• Cost
7
Richard Feynman,1959
There’s plenty of room
at the bottom
8
Eric Drexler, 1992
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President Clinton, 2000
The National Nanotechnology Initiative
“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.”
10
Terminology
The term “nanotechnology” is very popular.
Researchers tend to define the term to include
their own work. Definitions abound.
A more specific term:
“molecular nanotechnology”
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Arrangements of atoms
.
Today
12
The goal
.
13
New technologies
• Consider what has been done, and
improve on it.
• Design systems de novo based purely
on known physical law, then figure out
how to make them.
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New technologies
If the target is “close” to what we
can make, the evolutionary method
can be quite effective.
Target
..
What we can make today
(not to scale)
15
New technologies
Molecular
Manufacturing
But molecular
manufacturing systems
are not “close” to what we
can make today.
.
What we can make today
(not to scale)
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Working backwards
• 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
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Overview
Core molecular
Products
Products
manufacturing
Products
Products
capabilities
Products Products
Today
Products Products
Products Products
Products Products
Products
Products
Products
Products
Products
Products
Products
Products
Products
Products
Products Products
Products
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Scaling laws
Length
Area
Volume
Mass
Time
Speed
meter
meter2
meter3
kilogram
second
m/s
mm
mm2
mm3
mg
ms
mm/ms
0.001
0.000001
0.000000001
0.000000001
0.001
1
Chapter 2 of Nanosystems
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Molecular mechanics
• Manufacturing is about moving atoms
• Molecular mechanics studies the
motions of atoms
• Molecular mechanics is based on the
Born-Oppenheimer approximation
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Born-Oppenheimer
The carbon nucleus has a mass over
20,000 times that of the electron
• Moves slower
• Positional uncertainty smaller
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Quantum uncertainty

2


2 km
σ2:
k:
m:
ħ:
positional variance
restoring force
mass of particle
Planck’s constant divided by 2π
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Quantum uncertainty
•
•
•
•
C-C spring constant:
Typical C-C bond length:
σ for C in single C-C bond:
σ for electron (same k):
k~440 N/m
0.154 nm
0.004 nm
0.051 nm
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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
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Energy
Hydrogen molecule: H2
Internuclear distance
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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
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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
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What to make
Diamond physical properties
Property
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
Diamond’s value
9000
20
3.5 x 109 (natural)
1011 (natural)
5.5
1016 (natural)
3.51
0.8 x 10-6
2.41 @ 590 nm
0.05 (dry)
Comments
Extremely low
CBN: 4500 SiC: 4000
Ag: 4.3 Cu: 4.0
1011 (theoretical)
5 x 1011 (theoretical)
Si: 1.1 GaAs: 1.4
SiO2: 0.5 x 10-6
Glass: 1.4 - 1.8
Teflon: 0.05
Source: Crystallume
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Hydrocarbon bearing
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Hydrocarbon universal joint
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Rotary to linear
NASA Ames
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Bucky gears
NASA Ames
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Bearing
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Planetary gear
34
Neon pump
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Fine motion controller
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Positional assembly
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Stewart platform
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Thermal noise

σ:
k:
kb:
T:
2

k bT
k
mean positional error
restoring force
Boltzmann’s constant
temperature
39
Thermal noise

2

k bT
k
σ:
k:
kb:
T:
0.02 nm (0.2 Å)
10 N/m
1.38 x 10-23 J/K
300 K
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Stiffness
3 r E
4
k
3
4L
E:
k:
r:
L:
Young’s modulus
transverse stiffness
radius
length
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Stiffness
3 r E
4
k
3
4L
E:
k:
r:
L:
1012 N/m2
10 N/m
8 nm
100 nm
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Experimental work
Gimzewski et al.
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Experimental work
H. J. Lee and W. Ho, SCIENCE 286, p. 1719, NOVEMBER 1999
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Experimental work
I
I
Manipulation and bond formation by STM
Saw-Wai Hla et al., Physical Review Letters 85, 2777-2780, September
25 2000
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Buckytubes
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Experimental work
Nadrian Seeman’s
truncated octahedron from DNA
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Pathways
Self assembly of
a positional device
• Stiff struts
• Adjustable length
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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC
a
a a
a
|
| |
|
x
x x
x
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
a
|
x
joins the two struts
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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC
a c
a ca
c
a
|/
|/ |
/
|
xy
xy x
y
x
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
a
c
| and |
x
y
join the two struts
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Sliding struts
ABCABCABCABCABCABCABCABCABCABCABCABC
c
c
c
c
|
|
|
|
y
y
y
y
XYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZXYZ
c
|
y
Joins the two struts, which have now
moved over one unit.
Cycling through a-x, c-y and b-z produces
controlled relative motion of the two struts.
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Self replication
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Complexity (bits)
• Von Neumann's constructor
• Mycoplasma genitalia
• Drexler's assembler
• Human
• NASA
500,000
1,160,140
100,000,000
6,400,000,000
over 100,000,000,000
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Replication
There are many ways to make a
replicating system
There are nine and sixty ways
of constructing tribal lays,
And every single one of them
is right.
Rudyard Kipling
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Replication
There are many ways to make a
replicating system
•
•
•
•
•
•
•
Von Neumann architecture
Bacterial self replication
Drexler’s original proposal for an assembler
Simplified HydroCarbon (HC) assembler
Exponential assembly
Convergent assembly
And many more…
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Self replication
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);}
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Self replication
English translation:
Print the following statement twice, the second
time in quotes:
“Print the following statement twice, the
second time in quotes:”
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Self replication
The Von Neumann architecture
Universal
Computer
Universal
Constructor
http://www.zyvex.com/nanotech/vonNeumann.html
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Self replication
Elements in Von Neumann Architecture
• On-board instructions
• Manufacturing element
• Environment
• Follow the instructions to make a new
manufacturing element
• Copy the instructions
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Self replication
The Von Neumann architecture
Instructions
Manufacturing
element
New
manufacturing
element
http://www.zyvex.com/nanotech/vonNeumann.html
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Self replication
The Von Neumann architecture
Read head
Instructions
(tape)
Manufacturing
element
New
manufacturing
element
http://www.zyvex.com/nanotech/vonNeumann.html
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Self replication
Replicating bacterium
DNA
DNA Polymerase
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Self replication
Drexler’s proposal for an assembler
http://www.foresight.org/UTF/Unbound_LBW/chapt_6.html
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Broadcast architecture
Molecular
constructor
Molecular
constructor
Macroscopic
computer
Molecular
constructor
http://www.zyvex.com/nanotech/selfRep.html
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Broadcast architecture
Some broadcast methods:
Pressure (acoustic)
Electromagnetic (light, radio)
Chemical diffusion
Electrical
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Acoustic broadcast
• Can provide both power and control
• Multi-megahertz operation
• Moderate pressure (DP ~ one
atmosphere) can be reliably detected
with small pressure actuated pistons
• Feasible designs
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Pressure actuated device
External
gas
Actuator
(under tension)
Compressed gas
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Piston design issues
• External pistons to detect pressure changes
• Two pistons can drive a demultiplexor,
which in turn drives tens of signal lines
• Polyyne (carbyne) rods in buckytube
sheaths is adequate to convey force
(derailleur cable mechanism)
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Piston design issues
• 12 nm radius by 20 nm length for a volume
of about 9,000 nm3
• 105 Pa (~ one atmosphere) results in DP DV ~
10-18 Joules ~ 200 kT at room temperature
(high reliability)
• Force of ~45 piconewtons
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Broadcast replication
Advantages of broadcast architecture
• Smaller and simpler: no instruction storage,
simplified instruction decode
• Easily redirected to manufacture valuable
products
• Inherently safe
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HC assembler
Compressed
neon
Approximate dimensions:
1,000 nm length
100 nm radius
http://www.zyvex.com/nanotech/casing.html
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Broadcast replication
Elements in HC assembler
•
•
•
•
No on-board instructions (acoustic broadcast)
No on-board computer
Molecular positional device (robotic arm)
Liquid environment: solvent and three
feedstock molecules
• Able to synthesize most stiff hydrocarbons
(diamond, graphite, buckytubes, etc)
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Buckytubes as casings
• Well studied, robust
• Warning: synthesis of this casing will
not use anything resembling current
methods. Bucky tubes are well
understood and well studied,
simplifying design.
73
Replication
• An assembler manufactures two new
assemblers inside its casing
• The casings of the new assemblers
are rolled up during manufacture
• The original assembler releases the
new assemblers by releasing the
casing from the manufacturing
component
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Casing shape
•
•
•
•
Compressed neon to maintain shape
Pressure too low results in collapse
Pressure too high bursts casing
Pressures in the range of several tens
of atmospheres should work quite
well
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Feedstock
• Acetone (solvent)
• Butadiyne (C4H2, 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
• 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://www.zyvex.com/nanotech/
hydroCarbonMetabolism.html
(about two dozen reactions)
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HC assembler
Binding sites
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HC assembler
Freitas, adapted from Drexler
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HC assembler
Freitas, adapted from Drexler
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HC assembler
Subsystems
•
•
•
•
•
•
•
Casing
Binding sites (3)
Pistons (2)
Demultiplexor
Positional device
Tool synthesis
Zero residue
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Assembler design project
Design and modeling of HC
assembler feasible today
•
•
•
•
Speed development
Explore alternative designs
Clearer target
Clearer picture of capabilities
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Making diamond today
Illustration courtesy of P1 Diamond Inc.
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Molecular tools
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
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Hydrogen abstraction tool
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Other molecular tools
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C2 deposition
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Carbene insertion
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Micro rotation
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Exponential assembly
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Exponential assembly
•
•
•
•
•
No on-board instructions (electronic broadcast)
External X, Y and Z (mechanical broadcast)
No on-board computer
MEMS positional device (2 DOF robotic arm)
Able to assemble appropriate lithographically
manufactured parts pre-positioned on a
surface in air
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Convergent assembly
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Convergent assembly
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Convergent assembly
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Convergent assembly
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Replication
Take home message: the diversity of
replicating systems is enormous
• Functionality can be moved from the
replicating component to the environment
• On-board / off board instructions and
computation
• Positional assembly at different size scales
• Very few systematic investigations of the
wide diversity of replicating systems
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Replication
Take home message: and manufacturing
costs will be very low
• Potatoes, lumber, wheat and other
agricultural products have costs of roughly a
dollar per pound.
• Molecular manufacturing will make almost
any product for a dollar per pound or less,
independent of complexity. (Design costs,
licensing costs, etc. not included)
97
Replication
An overview of replicating systems
for 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
98
Replication
Popular misconceptions:
replicating systems must
•
•
•
•
•
be like living systems
be adaptable (survive in natural environment)
be very complex
have on-board instructions
be self sufficient (uses only very simple parts)
99
Replication
Misconceptions are harmful
• Fear of self replicating systems is based
largely on misconceptions
• Misplaced fear could block research
• And prevent a deeper understanding of
systems that might pose serious concerns
• Foresight Guidelines address the safety
issues
100
Replication
What is needed
• Development and analysis of more
replicating architectures
• Systematic study of existing proposals
• Education of the scientific community and
the general public
101
Impact
The impact
of a new manufacturing technology
depends on what you make
102
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
103
Impact
Lighter, stronger,
smarter, less expensive
• New, inexpensive materials with a strengthto-weight ratio over 50 times that of steel
• Critical for aerospace: airplanes, rockets,
satellites…
• Useful in cars, trucks, ships, ...
104
Impact
Nanomedicine
• 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
105
Impact
Nanomedicine
• 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.
106
Impact
Size of a robotic arm
~100 nanometers
8-bit computer
Mitochondrion
~1-2 by 0.1-0.5 microns
107
Impact
Mitochondrion
Size of a robotic
arm ~100
nanometers
“Typical” cell: ~20 microns
108
“Typical” cell
Mitochondrion
Molecular computer
+ peripherals
109
Remove infections
110
Clear obstructions
111
Respirocytes
http://www.foresight.org/Nanomedicine/Respirocytes.html
112
Release/absorb
• ATP, other metabolites
• Na+, K+, Cl-, Ca++, other ions
• Neurotransmitters, hormones,
signaling molecules
• Antibodies, immune system
modulators
• Medications
• etc.
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Correcting DNA
114
Nanomedicine Volume I
•
•
•
•
•
•
•
Nanosensors, nanoscale scanning
Power (fuel cells, other methods)
Communication
Navigation (location within the body)
Manipulation and locomotion
Computation
http://www.foresight.org/Nanomedicine
115
A revolution in medicine
• Today, loss of cell function results in
cellular deterioration:
function must be preserved
• With medical nanodevices, passive
structures can be repaired:
structure must be preserved
116
Temperature
Cryonics
Liquid nitrogen
Time
117
Clinical trials
•
•
•
•
Select N subjects
Vitrify 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?
118
Payoff matrix
It works
It doesn't
Experimental group
www.alcor.org
A very long and
healthy life
Die, lose life
insurance
Control group
Die
Die
119
Public perception
“Thus, like so much else in medicine, cryonics,
once considered on the outer edge, is moving
rapidly closer to reality”
ABC News World News Tonight, Feb 8th
“…[medical] advances are giving new credibility
to cryonics.”
KRON 4 News, NightBeat, May 3, 2001
120
Shirley MacLaine
“Everyone who has died
and told me about it has
said it’s terrific!”
121
Space
• Launch vehicle structural mass could
be reduced by about a factor of 50
• Cost per pound for that structural mass
can be under a dollar
• Which will reduce the cost to low earth
orbit by a factor of better than 1,000
http://science.nas.nasa.gov/Groups/
Nanotechnology/publications/1997/
applications/
122
Space
• Light weight computers and sensors
will reduce total payload mass for the
same functionality
• Recycling of waste will reduce
payload mass, particularly for long
flights and permanent facilities (space
stations, colonies)
123
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
124
Space
• Solar electric ion drive
• Thin (tens of nm) aluminum reflectors
concentrate light
• Arrays of small ion thrusters
• 250,000 m/s exhaust velocity
• Acceleration of 0.8 m/s
• Tour the solar system in a few months
K. Eric Drexler, Journal of the British Interplanetary Society,
V 45, No 10, pp 401-405 (1992).
Molecular manufacturing for space systems: an overview
125
Space
O’Neill Colonies
Dyson spheres
Skyhooks
Max population of solar system
126
Weapons
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://nano.xerox.com/nanotech/nano4/jeremiahPaper.htm
127
Weapons
Gray goo, gray dust, …
• New technologies, new weapons
• At least one decade and possibly a few
decades away
• Public debate has begun
• Research into defensive systems is
essential
128
The environment
Human impact
on the environment
• Population
• Living standards
• Technology
129
The environment
Reducing human impact
on the environment
• Greenhouse agriculture/hydroponics
• Solar power
• Pollution free manufacturing
130
How long?
• The scientifically correct answer is
I don’t know
• Trends in computer hardware suggest
early in this century — perhaps in the
2010 to 2020 time frame
• Of course, how long it takes depends
on what we do
131
Nanotechnology offers ...
possibilities for health, wealth,
and capabilities beyond most
past imaginings.
K. Eric Drexler
132
Positional assembly
Arranging Molecular Building Blocks
(MBBs) with SPMs
• Picking up, moving, and putting down a
molecule has only recently been
accomplished
• Stacking MBBs with an SPM has yet to be
done
134
Positional assembly
Designing MBBs and SPM tips
• The next step is to design an MBB/SPM tip
combination that lets us pick up, move, put
down, stack and unstack the MBBs
• A wide range of candidate MBBs are
possible
135
136
137
Energy
• The sunshine reaching the earth has
almost 40,000 times more power than
total world usage.
• Molecular manufacturing will produce
efficient, rugged solar cells and
batteries at low cost.
• Power costs will drop dramatically
138
Mitochondrion
Molecular bearing
20 nm scale bar
Ribosome
Molecular computer
(4-bit) + peripherals
139