Nanotech Scenario Series
PUBLISHED SEPTEMBER 2003
Technical Commentary on Greenpeace's Nanotechnology Report
The purpose of this document is to augment a portion of
the recent Greenpeace report on nanotechnology and artificial intelligence ("Future
Technologies, Today's Choices") and to comment on a few specific statements
in it. That report's treatment of
nanotechnology (MNT) was necessarily brief and did not cover several key
areas. The present document supplements Greenpeace's work, explores further some
of the misconceptions of MNT, and describes one area within MNT,
nanotechnology (LMNT), which is currently being pursued by most MNT
researchers. LMNT can produce most of the desired medical devices, advanced
materials, and product innovation goals sought after today and will be
significantly easier to achieve. The Center for Responsible Nanotechnology (CRN)
believes that recent advances in LMNT research should underscore to policy
makers the urgent need for discussion of possible consequences, both positive
The Greenpeace report covered two very large topics, nanotechnology and
artificial intelligence, so could devote only a few pages to MNT. Some important
MNT research is currently in press, and much published work has not yet been
synthesized into an accessible understanding of the recent developments in the
field. Some commentators outside the field continue to assert obsolete arguments
against MNT; this, as well as hype and misconceptions, further obscure the
picture and make it unfortunately easy to ignore even decade-old work. CRN's
focus on MNT provides a more accurate and detailed picture of the field's
This document builds its case in several sections. Following this introduction,
section II establishes a context
for discussing MNT, including a description of LMNT.
Section III covers the
requirements for developing LMNT, concluding that the barriers to rapid
development are mainly those of policy, not technology. There is no known
scientific objection to LMNT, and the technical problems are rapidly being
broken down into manageable sub-problems.
Section IV discusses the
probable capabilities and advantages of LMNT. The purpose of this is to
demonstrate that LMNT, though much easier than full MNT, may have nearly
equivalent power, desirability, and impact. This implies that a targeted rapid
development program may be launched for any of a variety of reasons in the near
Section V comments on specific
MNT-related claims of the Greenpeace report in light of the earlier sections. In
general, CRN agrees with them that MNT is possible, but does not agree that it
poses only long-term risks. Although the power and relative simplicity of LMNT
are not widely understood, the analysis is not difficult, and the knowledge has
been available worldwide for years. A targeted LMNT development program may
already be justifiable from an economic and/or military point of view. Such a
program could lead to a sudden shift in sociopolitical conditions, leaving
insufficient time to formulate policy.
Finally, section VI summarizes
CRN's understanding of MNT and LMNT, and repeats the call for policy attention
II. MNT Background
Although the word 'nanotechnology' has come to be applied to a wide range of
research and development activities, molecular nanotechnology (MNT) deserves
special consideration for several reasons. Most nanoscale technologies seek to
produce components that will be incorporated in larger products. By contrast,
MNT is proposed as a flexible manufacturing technology, capable of building
complete products. This would make it broadly applicable to a variety of
industries and applications.
The key point of MNT is mechanochemistry: the ability to make chemical reactions
happen under programmed control. In theory, this allows a few reactions, applied
in many positions, to build a large range of shapes. With careful control, and
assuming a suitable chemical toolbox can be developed, a mechanochemical
manipulator should be able to build shapes physically as complex as itself.
Molecular manufacturing should provide a variety of advantages, including less
complex fabrication, extremely predictable results, and strong, efficient
products, that would more than outweigh the difficulties of working in this
As noted in the Greenpeace report, MNT has been associated with unusual amounts
of hype. Early discussions asserted the ability to do almost anything that was
theoretically possible with chemistry. The unfortunate phrase 'universal
assembler' was coined, and rapidly attacked as being unworkable or at least too
difficult. Descriptions of MNT-built products usually did not specify what sort
of chemical assembly was to be used in making them, which lent an air of
unreality to the whole topic. Public debate has largely stuck there, obscuring
the fact that much research has been done since that time.
A body of work in the last decade has described a limited molecular
nanotechnology (LMNT) that is far better specified than the popular picture of
semi-magical nanobots. Starting with K. Eric Drexler's publication of
Nanosystems in 1992, LMNT has developed a comprehensive overview of the
requirements and functions of a limited molecular manufacturing capability based
on the carbon lattice configurations—diamond, graphite, and fullerenes—known
collectively as 'diamondoid'.
LMNT would implement only a tiny fraction of possible chemistry. Its chemical
requirement is simply to build shapes, components, and sub-micron machines out
of large, carefully fabricated, three-dimensional carbon molecules, with a few
other atoms thrown in as necessary to extend the range of surfaces and shapes.
However, it should be emphasized that this narrowing of technological focus
still allows for a wide range of powerful products, and many of the claims made
for the disruptive effects of MNT are still valid for LMNT.
One major change between traditional MNT and LMNT is the reduced emphasis on
nanobots. Early descriptions of MNT envisioned manufacturing accomplished by the
concerted action of legions of nanobot 'assemblers', floating around a growing
product in a tank. Alternatively, the assemblers could make nanobot products
that would do everything from cleaning your arteries to cleaning your house.
LMNT does not require nanobots at all. Instead of free-floating assemblers, the
mechanochemical fabricators would all be fastened down in a single
with their sub-products conveyed along fixed paths to be joined into bigger
components and finally large products. Some products of LMNT may be small
robots, but product robots require no onboard manufacturing capability, and the
appropriateness of using microscopic robots can be decided for each application
A useful nanofactory would be able to build products familiar to today's
engineers and users, without requiring the product designers to be experts in
chemistry. This appears possible through the re-use of a few basic nanoscale
components to build micro-scale systems. CRN has a
paper in press discussing nanofactory architecture, bootstrapping, and
product design. Most product design would be carried out on the micro level,
using 'libraries' of pre-designed 'nanoblocks'; computer software is already
designed this way.
III. Development of Molecular Nanotechnology
If molecular nanotechnology is to be developed, even in limited form, several
hurdles must be overcome. This section describes the physics, research,
engineering, schedule, economic, and policy problems that LMNT may encounter.
As far as is known, the laws of physics do not in any way prevent LMNT from
working as described in this document. Atoms are moved by thermal noise and
quantum effects, but these effects are small at room temperature—if this were
not the case, our bodies could not function. Like any other working system, LMNT
manufacturing systems and products will produce heat, and require an energy
source. However, these are engineering details, not fundamental hurdles.
Likewise, the need to design and control vast numbers of sub-components is an
engineering problem; as discussed later, it does not appear to be intractably
difficult for certain classes of useful systems.
The chemical techniques required, though not yet fully
investigated, do not appear to be a showstopper. Greenpeace correctly notes that
Richard Smalley's "fat fingers" and "sticky fingers" theories are the most
carefully thought out objections to MNT. However, it should be further noted
that, in fact, not much thought went into these objections: published proposals
for mechanochemistry do not involve "fingers" at all. The recent achievement of
mechanochemistry on a silicon lattice demonstrates that if Smalley's objections
are relevant at all, their scope must be limited—they certainly do not
constitute a blanket disproof of the feasibility of MNT, much less LMNT.
The next question is how MNT could be achieved in practice. For LMNT, one
possible course has three milestones. First, a set of mechanochemical reactions
must be researched and developed, capable of making several forms of diamondoid
from simple 'feedstock' chemicals. Second, a small fabricator must be designed
and built, capable of carrying out the necessary manipulations to perform the
mechanochemistry. Finally, large numbers of these fabricators must be combined
with other equipment to make a nanofactory.
The first step, developing the necessary carbon-bonding reactions, will require
much scientific research. The theoretical groundwork for this was laid in
Nanosystems, with significant subsequent work by Ralph Merkle and Robert
Freitas, including a book in progress on diamond surface chemistry. The second
step, building a fabricator, will require mechanical and chemical engineering
for the design, and a lot of lab work including the development of new
techniques for the construction. It should be noted that the fabricator need not
be autonomous in any sense; it would use only specialized chemicals, and would
be inert without outside control and power. Once a fabricator is specified, a
nanofactory can be designed. CRN's
discusses nanofactory design and bootstrapping. It appears likely that this
final step will be the easiest.
Much work will be required to accomplish the LMNT goal of making a diamondoid
nanofactory. Some observers predict that the field will develop slowly, with
much of the necessary research happening as an outgrowth of other projects.
However, as discussed in the next section, the economic and/or military rewards
of a successful LMNT project could be extreme. This indicates that at some
point, perhaps soon, it will be worthwhile for someone to launch a targeted
development project. If successful, the resulting nanofactory would find
immediate use in a variety of applications, probably including the replacement
of traditional fabrication technologies for many products.
The utility of LMNT depends largely on the capability of the nanofactory. In
order to achieve a useful fabrication speed, the factory must contain myriad
separately-controlled workstations making sub-micron parts a few atoms at a
time, which would then have to be joined. This would require automated control
and high reliability. Detailed calculations indicate that mechanochemical
fabrication of stiff diamondoid parts could be sufficiently reliable at room
temperature. CRN's nanofactory paper describes a mechanical joint that allows
simple robotics to work with a high degree of reliability. A useful nanofactory
would also have to be fast, easy to use, and cheap to operate; these
requirements also appear to be achievable with fairly straightforward factory
At some point, the cost of an LMNT project will become comparable with the cost
of developing a new military airplane—tens of billions of dollars—if it hasn't
already. As discussed below, LMNT would facilitate the rapid development of a
variety of powerful new weapon systems, as well as enhancements to existing ones
and great improvements in military logistics. Economic incentives for commercial
development are also immense; from computers to medical instruments, the range
of products that could benefit from LMNT is broad enough to warrant a high level
It appears that the main barriers to development of LMNT are matters of policy.
Uncertainty about its ultimate feasibility, though widespread in the United
States and Europe, is unfounded. Uncertainty about the roadmap for technological
development should at this point be addressable by theoretical studies, and in a
crash project could be handled by concurrent exploration of multiple avenues as
was done in the Manhattan Project. Although MNT has not yet come under
regulation, this could present an additional hurdle to commercial development in
some jurisdictions, though probably not to military development.
IV. Functionality of LMNT
This section discusses the consequences of the development of a limited
molecular nanotechnology: a tabletop manufacturing system capable of making
nanoscale carbon-lattice parts and integrating them into a human-scale product.
In reading this section, it is important to keep two things in mind. First,
although speculative, the capabilities described here are well grounded in
current scientific theory and peer-reviewed publication. Second, although much
work will be required to develop LMNT, much of this work can be started today
and done in parallel; the development schedule depends largely on the incentive,
not on any technological or scientific difficulty. As this section demonstrates,
the incentive could be quite high.
Building at the molecular level, millions of parts could fit into the volume of
a bacterium. Product designs would combine predefined and tested micron-scale
machines—computers, sensors, and actuators, as well as inert structure—to make
human-scale products with as little or as much complexity as desired. The
extreme flexibility provided by nanomodular design would allow a wide range of
products to be created by the same factory technology.
A variety of estimates indicate that the time required for a sub-micron
mechanochemical fabricator to produce its own mass of product is probably well
under a day—comparable to bacterial replication times. Thus a tabletop
nanofactory could probably make a one-kilogram diamondoid product in an hour or
so. It could also fabricate a duplicate of itself in under a day, at a cost
comparable to the cost of any product. This implies that the manufacturing base
could grow quite rapidly.
Being self-contained and automated, a nanofactory would be usable in a variety
of environments, including areas with undeveloped infrastructure and near
battlefields. It would also be suitable for manufacturing products near point
and time of sale, and perhaps even for home use. Products built largely of
simple carbon-based feedstock molecules would not need the metals or specialized
materials used in today's technology. These factors could greatly decrease
transportation, storage, labor, and inventory costs, and permit more rapid
delivery of newly designed products.
A nanofactory could function as both a rapid prototyping machine and a
production system. Just as a computer uses a few basic instructions to do many
kinds of calculations, a nanofactory could use a few basic operations of
mechanochemistry and assembly to build many kinds of products without retooling
or prototype costs. This also implies that product manufacturing cost would be
unrelated to product complexity. A new product design could be built straight
from the blueprints in minutes or hours, tested and refined, and a new version
built as soon as the new design was ready. The final version's blueprint could
immediately be put into production at any location on any desired number of
nanofactories. Development of new products could proceed far more quickly than
today's practice allows.
Products built by a nanofactory would be limited by the underlying chemistry.
However, mechanical devices depend on shape, not chemistry; most mechanical
products would be achievable at all scales larger than one nanometer. Because
some forms of carbon conduct electricity or are semiconductors, many electrical
devices would also be achievable. There are also several ways in which a carbon
lattice device could interact successfully with biochemical molecules.
Products built of diamond lattice would also have several advantages. Most
obvious is strength: carbon lattice may be 100 times as strong as steel.
Nanofactory-built products could require far less material than today's
versions. The ability to design at nanometer scale allows many products,
including computers and motors, to be far more compact; a supercomputer could
fit inside a grain of sand and use a fraction of a watt. The precision of
molecular design should allow bearings to be nearly frictionless, in contrast
with today's MEMS devices. Most human-scale products would be mostly empty
space, giving mechanical engineers unprecedented freedom to design function
rather than structure and further simplifying the design process.
Weapons are one obvious application of such a manufacturing technology.
Aerospace hardware, especially the avionics, could be far lighter and stronger.
New kinds of weapons could be developed, smaller (or larger), more powerful, and
more complex than today's systems. If prototypes could be produced rapidly at
low cost, designers could get much more inventive. With manufacturing cost
unrelated to complexity or miniaturization, even the smallest weapons could have
a full onboard computer/sensor/actuator suite, and be produced in sufficient
quantity to compensate for their size. As with all nanofactory products,
deployment would be almost immediate and require little effort. CRN is
particularly concerned about the possibility of an unstable arms race fueled by
ultra-rapid development of weapons of unprecedented power and functionality.
The same factors that could make even limited MNT a powerful military force
multiplier may also make it a powerful economic asset. It's said that in order
to be accepted, an innovation has to be ten times better than what it replaces.
According to calculations, depending on the criterion, LMNT products could be
between one hundred and one million times better. Reduced costs, easier product
development, and easier manufacturing could make LMNT products even more
attractive. The flexibility of the manufacturing process means that a wide range
of products could be produced. LMNT could provide a substantial economic boost
to undeveloped areas, since a nanofactory would require very little
infrastructure. Whoever controls LMNT could end up dominating a wide range of
industries, and disrupting many others.
V. Discussion of Greenpeace Report
Here we will comment on a few specific points raised in the report published by
In section 2.4.2, and again in 2.6, the report predicted that MNT would be
developed about 35 years in the future. This appears to be based on two
assumptions: first, that full MNT is necessary for full effects, and second,
that development will not be accelerated by a crash project. Both of these
assumptions are questionable. Limited MNT, as outlined here, would produce most
of the benefits and risks of full MNT. However, it could be developed quite a
bit sooner and with less uncertainty. This in turn increases the military and
commercial incentives for early development, even to the extent of justifying
targeted multi-billion dollar projects.
In section 22.214.171.124, the report mentions nanobots and nanomedical devices as an
area of exceptional hype. This has been an area of great confusion, especially
since traditional MNT discussion frequently has failed to distinguish between
nanobot fabricators and nanobot products. LMNT fabrication does not rely on
nanobots at all. However, it could easily build a variety of nanobot-type
products incorporating nanometer-scale diamondoid components. With a limited
chemistry toolbox, LMNT products may not be able to interact fully with
biochemistry. However, simple tools such as microsurgical robots and
high-capacity implantable sensor arrays could cause rapid improvement in some
areas of medical practice.
Section 2.4.3 is titled "Fundamental barriers to these visions," and states that
some "major technical obstacles ... might be virtually insurmountable." As
discussed above, Richard
Smalley's "fat fingers" and "sticky fingers" criticisms have little or no
relevance to LMNT. The report correctly notes that "Diamond assemblies might be
relatively easy to assemble; other structures, such as biological
configurations, are infinitely more complicated." As the present document
demonstrates, diamond assemblies—LMNT—could accomplish much of what has been
claimed for MNT. Finally, the "major problems concerning energy sources and
dissipation" and similar practicalities have been addressed in detail in CRN's
forthcoming exploration of nanofactory architecture. No fundamental barriers to
LMNT are known or even suspected at this time.
Section 2.5.1 defines as "long-term" any hazard that "due to challenges
associated with technological development, is unlikely to manifest itself within
a 10-15 year time frame." CRN believes that in the case of LMNT, hazards that
may occur ten years from now need attention today. An LMNT development program
could proceed with surprising speed, especially in the final stages, which
according to our research will probably require mainly traditional engineering.
The time to start making policy is before such a program is launched; given the
incentives described here, and the recent progress in defining the tasks
required by LMNT, such a program could be initiated at any time.
Section 126.96.36.199 discusses self-replication and biosphere destruction, saying
that "...while the danger seems slight, even a slight risk of such a catastrophe
is best avoided." It should be emphasized that the development and use of LMNT
manufacturing does not involve self-replication. A nanofactory would be able to
duplicate its physical structure, if the right set of blueprints were
downloaded. However, it would include no manipulators to gather biomaterial, no
legs or wheels to travel, no chemical plant to process biomaterial into pure
feedstock chemicals, and no power supply. The chance of such a thing running
amok is not merely slight—it is zero. There is, unfortunately, a slight risk of
some malicious or irresponsible person deliberately integrating all the
necessary components to create a self-replicating machine, but such a project
would be quite difficult, and this risk is overshadowed by the more powerful
non-replicating weapons that could be designed and built with much less effort.
Section 188.8.131.52 points out the dangers of a "nano-divide" in which only the rich
would have access to the new technology. CRN shares this concern, especially
since denial of the technology to any population would fuel demand for illicit
and uncontrolled versions. A more optimistic scenario is one in which
nanofactories are made widely available, and noncommercial designs could be
manufactured at cost. The Open Source software movement has demonstrated its
ability to produce high-quality, free, complex digital products; its methods and
practices would be highly applicable here. Unfortunately, this scenario could be
sabotaged by current trends in intellectual property that will take time to
reverse—another reason why MNT policymaking should begin now.
Section 184.108.40.206 discusses destructive uses of MNT. CRN emphatically shares this
concern. An international organization may be necessary to monitor military uses
of MNT or development of unmonitored fabrication capability. LMNT could be
developed with surprising speed, and could proliferate with even greater speed
once the first nanofactory is functional; additionally, with just a little
reverse engineering or information sharing, subsequent development projects
could progress much faster than the initial project. The initial stages of such
a project, involving distributed lab work and computational experiments, would
be relatively easy to conceal, and the final stages could proceed quite quickly.
If a cooperative international response will be necessary, planning must start
long before the problem appears urgent.
A few minor inaccuracies in the report are worth pointing out. Section 220.127.116.11
states that fourth-generation nuclear devices incorporate nanotechnology. In
fact, they would use MEMS and precise machining—much more prosaic technologies.
Section 18.104.22.168 describes the NanoWalker as an "autonomous miniature robot." It
should be noted that "autonomous" here merely means that NanoWalkers are
controlled by infrared signals rather than by wires, and that they can move
around a workspace; they are not capable of performing tasks on their own.
Section 2.5.4 describes the Foresight Institute as following a strategy of "launch[ing]
pre-emptive strikes against any problems with public acceptance of
nanotechnology." In fact, Foresight was founded in order to call attention to
the risks of molecular nanotechnology and other advanced technologies.
The Greenpeace report correctly notes that molecular nanotechnology appears to
be possible, and could have significant negative impacts. However, their
analysis is based on an early understanding of MNT, and does not take into
account the limited MNT that has been proposed more recently and developed in
more detail. LMNT would be much simpler and cheaper to develop, and powerful
enough to be extremely attractive to a variety of interests. If there is not
already a targeted LMNT development program somewhere in the world, there
probably will be soon.
Although some of the consequences of traditional MNT, such as self-replicating
nanobots, become less significant with LMNT, other potential consequences remain
areas of considerable concern. The sudden discovery of an LMNT project nearing
completion would not allow time for formulating and implementing good policy. It
should be emphasized that the final stages of LMNT development are likely to be
the easiest and most rapidly accomplished. Hurried or panicked policy would
likely be both oppressive and inadequate to prevent the negative consequences,
including geopolitical instability, economic disruption, and a variety of
unfortunate products and capabilities being widely accessible.
However, cautionary discussions should not ignore the fact that MNT, including
LMNT, could be a strong positive asset. If administered well, the existence of
cheap, clean, local, easy-to-use manufacturing capability (even limited to
diamondoid products) could go a long way toward reducing poverty and
underdevelopment, as well as alleviating current environmental impacts. Whether
suitable administration can be developed depends largely on how soon the policy
Future Technologies, Today’s Choices (Greenpeace report)
K. Eric Drexler,
Nanosystems: Molecular Machinery, Manufacturing, and Computation, John
Wiley & Sons, 1992.
Feasibility of Molecular Manufacturing (Foresight Institute)
Projected Environmental Impacts of
Research: Current Results
This commentary was prepared by
Chris Phoenix, CRN's Director of Research.