Foresight Update 2 (page 2)
A publication of the Foresight Institute
Many readers have requested news and references on technical progress related
to nanotechnology. The brief summaries below cover some recent advances
in the three enabling technologies of chemistry, micromanipulation, and
Although many orders of magnitude larger than nanomachines, the micromechanical
systems work by W. Trimmer and K. Gabriel at Bell Labs explores the feasibility
of small electrostatic motors, a concept also useful on the nanometer scale.
Assuming the use of standard electronic materials (silicon wafers, etc.)
they present designs for electrostatic motors with diameters as small as
1 mm (Sensors and Actuators, 11, p189).
Joined by first author M. Mehregany, they have fabricated silicon gears
down to a diameter of 300 microns and a micro-turbine that turns at up to
24,000 rpm (draft, "Micro Gears and Turbines Etched from Silicon.")
On the micromanipulation path, R. Becker et al., also of Bell Labs,
have used a scanning tunneling microscope to make atomic-scale modifications
to a surface, albeit with limited control; see
discussion in this issue (Nature, 29Jan87, p419).
On the chemical path to nanotechnology, J.
Rebek of U. Pittsburgh has found that synthetically-accessible small
molecules can be designed to "recognize" acids, bases, amino acids,
metal ions, and neutral substrates, abilities once assumed to require complex
biological macromolecules. It is suggested that such small molecules can
be designed and efficiently assembled to recognize almost any small molecule
or ion, and that carbohydrates, peptides, and nucleotides will also be recognizable
in this way (Science, 20Mar87, p1478).
The protein design path is being pursued vigorously. Scripps Clinic has
received a $2.72 million NIH grant to study protein folding. Principal investigator
A. Olson plans to
combine NMR and X-ray crystallography data with computer graphics techniques
(Genetic Tech. News, Sep87, p8).
C. Pabo and E.
Suchanek of Johns Hopkins School of Medicine have a program, PROTEUS, which
tests proposed modifications to a protein and could be used in de novo design
as well, perhaps by starting with the desired backbone and then adding side
chains (Biochem, 25, p5987--MEDLINE
Abstract). J. Ponder and
F. Richards of Yale propose to develop templates derived from the tertiary
(i.e., high-level folding) structure of known sequenced proteins. New sequences
could be tested against the templates to see whether they are likely to
fold in a known way (J Mol Biol, 193, p775--MEDLINE
Abstract). Both groups cite Drexler's
1981 PNAS paper as a source for their general approach.
et al. of the University of London advocate use of a knowledge-based
approach for prediction of protein structures and the design of novel molecules,
using analogies between the protein being modeled and known proteins. Subsequent
X-ray analysis of several modeled proteins showed good agreement with the
predicted shape (Nature, 26Mar87, p347--MEDLINE
J. Leszczynski and
G. Rose of Penn State
have identified a new type of protein secondary structure termed the omega
loop, an omega-shaped structure extending out from the protein surface.
These loops could have important roles in recognition and may serve as convenient
modules for use in protein design (Science, 14Nov86, p849--MEDLINE
A. Napper et al. of Penn State and Scripps have used an evolutionary
approach based on variation and selection within an organism's immune system,
rather than deliberate design, to find a new agent of catalysis for a given
chemical reaction. They obtained monoclonal antibodies elicited by an analog
of the reaction's transition state, then used the antibodies as catalysts,
facilitating formation of the transition state and increasing the reaction
rate by a factor of 170 (Science, 28Aug87, p1041--MEDLINE
A. Lapedes and R. Farber at Los Alamos are using neural-net simulation on
a supercomputer to predict which short DNA sequences code for proteins and
which do not, with 80% accuracy compared to 50% using conventional methods.
Both they and, in parallel, T. Sejnowsi of Johns Hopkins are using similar
techniques to try to predict a protein's structure from its sequence (Sci
News, 1Aug87, p76).
R. Altman and O.
Jardetzky of Stanford maintain that knowing the behavior and structure
of proteins in solution, rather than in crystals, is of critical interest.
They use an expert system to determine which structures are compatible with
experimental data--e.g. from NMR--on proteins in solution (J
Biochem, 100, p1403--MEDLINE
Tiedje has found a novel anaerobic bacterium capable of dechlorinating
aromatic compounds, showing that natural molecular machines can carry out
unusual reactions needed to clean up toxic waste (Science,
28Aug87, p975). Specially designed nanomachines should be able to tackle
even tougher cleanup tasks.
J. McBride of Yale, et al.,
discuss the chemistry which occurs under high stress within organic single
crystals (Science, 14Nov86, p830). Such high-stress conditions,
with spontaneous mechanical forces equivalent to tens of thousands of atmospheres,
give some indication of the chemistry that could be done by an assembler
able to hold molecules firmly, and push.
Table of Contents - Foresight
A "hypertext system" can be anything from a hyper-notepad
to a hyper-Library-of-Congress
Interest in hypertext is exploding, for the time being. Dozens of systems
are in use, the University of North Carolina, the ACM, and the IEEE have
sponsored a conference, and Apple Computer has massively promoted a new
hypertext product for the Macintosh, HyperCard. There have
been hopes of a hypertext revolution bringing an impact on the scale of
the Gutenberg revolution. It seems to have arrived.
Or has it? Words can mean many things. A "programming language"
can be anything from a system of detailed instructions for pushing bits
around inside a computer, to a system of general rules for describing logical
reasoning. A "hypertext system" can be anything from a hyper-notepad
to a hyper-Library-of-Congress. Present systems are closer to the notepad
class. We shouldn't expect them to give library-class performance.
Different hypertext systems have been built to serve different goals, though
some aim to serve several. One goal is to improve personal filing systems
by helping people connect information in ways that reflect how they think
about it. Another is to improve educational publications by helping authors
connect information in rich, explorable networks. Many recent hypertext
systems are actually hypermedia systems in which authors can link descriptions
to pictures, video, and sound.
Filing systems on a single machine can serve a single user or a small group.
Teaching documents written on one machine, can be copied and distributed
to other machines around the world. Both these goals can be served by stand-alone
systems on single machines, such as HyperCard on the Macintosh. But both
these goals, though valuable, are peripheral to the goal of evolving knowledge
more rapidly and dependably, to improve our foresight and preparedness.
An improved medium for evolving knowledge would aid the variation and selection
of ideas. To aid variation essentially means to help people express themselves
more rapidly, accurately, and easily. To aid selection essentially means
to help people criticize and evaluate ideas more rapidly, effectively, and
easily. Several characteristics of a hypertext system are important to these
To help critical discussion work effectively, a hypertext system must have
full links, followable in both directions, rather than just references
followable in a single direction. That is, the system must support full
hypertext, not just semi-hypertext. In a semi-hypertext system, a reader
cannot see what has been linked to a document, hence cannot see other reader's
annotations and criticisms. Many existing hypertext systems lack full links.
To help express criticism, a hypertext system should be fine-grained.
In a fine-grained system, anything--not just a document, but a paragraph,
sentence, word, or link--can be the target of a link. In a fine-grained
hypertext system, if you wanted to disagree with this article, you could
express yourself by linking to the objectionable part (perhaps the definition
of fine-grained in the previous sentence). In a coarse-grained system, you
might have to link to the article as a whole. Many existing hypertext systems
To make the system a useful medium of debate, it must be public. This in
turn requires suitable software, access policies, and pricing policies (such
as fee-for-service, rather than free-to-an-elite). No hypertext system yet
functions as a genuine public medium; many cannot do so.
To work, a public hypertext system must support filtering software. If readers
automatically see all the links to a document, the equivalent of a presidential
speech or an Origin of Species will become incredibly cluttered.
Software mechanisms can provide a flexible way to cut through the clutter,
enabling readers to be more choosey, seeing only (say) links that other
readers (editors, colleagues, etc.) have recommended. There are subtleties
to making filtering work well, but promising approaches are known; readers
would be free to use whichever filters they think best at the moment, so
filters would be free to evolve.
No existing hypertext system is full, fine-grained, filtered, and public--yet
all of these characteristics (with the possible exception of "fine-grained")
seem essential in a system that can make a qualitative difference in the
evolution of knowledge. They are needed if we are to have a genuine hypertext
It is this sort of system--not "a hypertext system" but a hypertext
publishing system--that can make a real difference to society's overall
intellectual efficiency, and overall grasp of complex issues. How great
a difference? Even a small improvement in something so fundamental to our
civilization would save billions of dollars, lengthen millions of lives,
and give us a better chance of surviving and prospering through the coming
technological revolutions. And there is reason to think the improvement
might not be small.
Table of Contents - Foresight
Enzymes show that a nanomachine needn't have gears and bearings, but macroengineering
shows how useful these parts can be. Conventional gears and bearings are
built to tight tolerances--bumps a thousandth of an inch high on a one-inch
part would often be too large. Since an atomically smooth surface is bumpy
on a tenth-nanometer scale, it might seem that gears and bearings couldn't
be reduced below 100 nm or so. A complex nanomachine using gears and bearings
would then be huge--entire microns across.
A paper on "Nanomachinery: Atomically Precise Gears and Bearings"
(by K. Eric Drexler, to appear in the proceedings of the November, 1987,
IEEE Micro Robots and Teleoperators Workshop) examines how to build these
devices much smaller. The essential insight is that an atom's surface is
a soft, elastic thing, helping to smooth interactions. Conventional gears
need precisely machined teeth if their hard surfaces are to mesh smoothly,
but nanogears can use round, single-atom teeth, relying on atomic softness
to aid smooth meshing.
This principle can also be applied to bearings. In one approach, two surfaces
can slide on roller bearings. The bearings can roll smoothly, despite atomic
bumpiness, by having a pattern of surface bumps that meshes smoothly, gear-fashion,
with a similar pattern of bumps on the bearing race.
- For an extension of the IEEE Workshop paper, see section 10.4
Mathematical analysis shows that two surfaces (of a shaft in a sleeve, for
example) can slide smoothly over one another if their bumps are spaced to
systematically avoid meshing. In effect, the bumps cancel out--while one
is pushing back, another is pushing forward. With a ring of six atoms sliding
within a ring of 22, for example, the friction force can be less than one
billionth of the force holding two atoms together in a molecule.
Yet another class of bearing avoids atomic bumpiness by using a single atom
or bond as a bearing. A fraction of a nanometer across, these bearings are
as small as the moving parts in a nanomachine can possibly be.
Table of Contents - Foresight
The proceedings volume from MEDIII (the Third International Symposium on
Molecular Electronic Devices) has been delayed, but we can give a few notes
on the meeting here. It was indeed international, with attendees from Europe,
Japan, and Argentina as well as the US. A speaker from the USSR was scheduled,
but failed to appear.
Besides many papers on conducting polymers and thin films, there were talks
more directly relevant to nanotechnology. S.
Staley of Carnegie-Mellon's Center for Molecular Electronics discussed
work on an optically-switched molecular NAND gate. J. Milch of Eastman Kodak
proposed using a molecular crystal as a cellular automaton, reminiscent
of Conway's Game of Life, leading to a molecular computer.
J. Deisenhofer of the Max-Planck Institut discussed work on a molecular
electronic system found in living cells, the light-driven charge separation
process of photosynthesis in purple bacteria. E.
Greenbaum of Oak Ridge National Lab presented experimental results on
connecting photosynthesizing molecular systems to external electric circuits
by means of colloidal platinum directly contacting the molecules. E. Drexler
presented the nanocomputer rod logic work cited in our previous issue.
This young, chaotic field also made progress by starting to standardize
its terminology. The one-page handout distributed by workshop organizers,
"Molecular Electronics and Technology: Some proposed distinctions and
terms," is available from the FI office.
Table of Contents - Foresight
Britain Spearheads "Nanotechnology"
or What is Nanotechnology?
Under the headline "Funds for Nanotechnology," Britain's IEE
News (October 1987) reports that "Funds are now available through
the National Physical Laboratory ... for the support of projects which will
lead to the commercial exploitaton of nanotechnology techniques. Nanotechnology
covers the manufacture and measurement of devices and products where dimensions
or tolerances are in the range 0.1 to 100 nm..." This sounds exciting
until one realizes that this definition of "nanotechnology" covers
everything from memory chips to electron microscopy.
The use of the term "nanotechnology" for everything smaller than
100 nanometers (0.1 micron) is apt to lead to confusion. As used in recent
years in the US (and in this publication), "nanotechnology" implies
a general ability to build structures to complex, atomic specifications;
it refers to the technique used rather than to the size of the product.
We can see a parallel in the term "microtechnology": the broad
ability to shape bulk materials into surface patterns having complex specifications
on a scale of microns or less. This term does not apply to all processes
having micron-scale products. Consider the case of a forest fire simulation
experiment for which micron-sized particles of smoke are needed--the fire
we set to produce these particles is not an example of microtechnology.
Like nanotechnology, the term refers to a family of techniques and abilities,
not size and scale. In the case of nanotechnology, this means structuring
matter atom-by-atom with precise control. Some products of nanotechnology,
such as fracture-tough diamond composite spacecraft, will not be small.
Nanotechnology is qualitatively different from microtechnology, being based
on molecular operations rather than the miniaturization of bulk processes.
It will enable a cube 0.1 micron on a side to hold, not just a single device,
but the equivalent of an entire microprocessor. It will lead to far more
than just denser circuits, more precise machines, and so forth--it will
lead to self-replicating machines, cell repair systems, and a broad, deep
revolution in technology, economics, and medicine.
The advance of microtechnology into the submicron regime no more calls for
a change of prefix than did the similar advance of microscopy--we do not
speak of "electron nanoscopes." If "nanotechnology"
becomes a trendy term for submicron technology, we are in for some confusing
times and a lot of wasted words used in describing assembler-based technology.
The IEE News article holds no hint of real nanotechnology.
Readers are encouraged to state their opinions on this matter to editors
of publications which misuse the term.
One cubic nanometer of diamond, containing 176 atoms. A cube 100 nm on a
side would contain 176 million atoms.
Table of Contents - Foresight
Foresight thanks Dave Kilbridge for converting Update 2 to html for this
From Foresight Update 2, originally published 15
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