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So
what's the big deal about molecular manufacturing? We have
lots of kinds of nanotechnology. Biology already makes things
at the molecular level. And won't it be really hard to get
machines to work in all the weirdness of nanoscale physics?
The
power of molecular manufacturing is not obvious at first.
This article explains why it's so powerful--and why this power
is often overlooked. There are at least three reasons. The
first has to do with programmability and complexity. The second
involves self-contained manufacturing. And the third involves
nanoscale physics, including chemistry.
It
seems intuitively obvious that a manufacturing system can't
make something more complex than itself. And even to make
something equally complex would be very difficult. But there
are two ways to add complexity to a system. The first is to
build it in: to include lots of levers, cams, tracks, or other
shapes that will make the system behave in complicated ways.
The second way to add complexity is to add a computer. The
computer's processor can be fairly simple, and the memory
is extremely simple--just an array of numbers. But software
copied into the computer can be extremely complex.
If
molecular manufacturing is viewed as a way of building complex
mechanical systems, it's easy to miss the point. Molecular
manufacturing is programmable. In early stages, it will be
controlled by an external computer. In later stages, it will
be able to build nanoscale computers. This means that the
products of molecular
manufacturing can be extremely complex--more complex than
the mechanics
of the manufacturing system. The product design will be limited
only by
software.
Chemists
can build extremely complex molecules, with thousands of atoms
carefully arranged. It's hard to see the point of building
even more complexity. But the difference between today's chemistry
and programmable mechanochemistry is like the difference between
a pocket calculator and a computer. They can both do math,
and an accountant may be happy with the calculator. But the
computer can also play movies, print documents, and run a
Web browser. Programmability adds more potential than anyone
can easily imagine--we're still inventing new things to do
with our computers.
The
true value of a self-contained manufacturing system is not
obvious at first glance. One objection that's raised to molecular
manufacturing is, “Start developing it--if the idea is any
good, it will generate valuable spinoffs.” The trouble with
this is that 99% of the value may be generated in the last
1% of the work.
Today,
high-tech intricate products like computer chips may cost
10,000 or even 100,000 times as much as their raw materials.
We can expect the first nanotech manufacturing systems to
contain some very high-cost components. That cost will be
passed on to the products. If a system can make some of its
own parts, then it may decrease the cost somewhat. If it can
make 99% of its own parts (but 1% is expensive), and 99% of
its work is automated (but 1% is skilled human labor), then
the cost of the system--and its products--may be decreased
by 99%. But that still
leaves a factor of 100 or even 1,000 between the product cost
and the raw materials cost.
If
a manufacturing system can make 100% of its parts, and build
products with 100% automation, then the cost of duplicate
factories drops precipitously. The cost of building the first
factory can be spread over all the duplicates. A nanofactory,
packing lots of functionality into a self-contained box, will
not cost much to maintain. There's no reason (aside from profit-taking
and regulation) why the cost of the factory shouldn't drop
almost as low as the cost of raw materials. At that point,
the cost of the factory would add almost nothing to the cost
of its products. So in the advance from 99% to 100% self-contained
manufacturing, the product cost could drop by two or three
orders of magnitude. This would open up new applications for
the factory, further increasing its value.
This
all implies that a ten billion dollar development program
might produce a trillion dollars of value--but might not produce
even a billion dollars worth of spinoffs until the last few
months. All the value is delivered at the end of the program,
which makes it hard to fund under American business models.
A
factory that's 100% automated and makes 100% of all its own
parts is hard to imagine. People familiar with today's metal
parts and machines know that they wear out and require maintenance,
and it's hard to put them together in the first place. But
as nanoscientists keep reminding us, the nanoscale is different.
Molecular parts have squishy surfaces, and can bend without
breaking or even permanently deforming. This requires extra
engineering to make stiff systems, but diamond (among other
possibilities) is stiff enough to do the job. The squishiness
helps when it's time to fit parts together: robotic assembly
requires less precision. Bearing surfaces can be built into
the parts, and run dry. And because molecular parts (unlike
metals) can have every atom bonded strongly in its place,
they won't flake apart under normal loads like metal machinery
does.
Instead
of being approximately correct, a molecular part will be either
perfect--having the correct chemical specification--or broken.
Instead of wearing steadily away, machines will break randomly--but
very rarely. Simple redundant design can keep a system working
long after a significant fraction of its components have failed,
since any machine that's actually broken will not be worn
at all. Paradoxically, because the components break suddenly,
the system as a whole can degrade gracefully, while not requiring
maintenance. It should not be difficult
to design a nanofactory capable of manufacturing thousands
of times its own mass before it breaks.
To
achieve this level of precision, it's necessary to start with
perfectly identical parts. Such parts do not exist in today's
manufacturing universe. But atoms are, for most purposes,
perfectly identical. Building with individual atoms and molecules
will produce molecular parts as precise as their component
atoms. This is a natural
fit for the other two advantages described above—programmability,
and self-contained automated manufacturing. Molecular manufacturing
will exploit these advantages to produce a massive, unprecedented,
almost incalculable improvement over other forms of manufacturing.
To donate to the Center for Responsible Nanotechnology, go
to
http://crnano.org/support.htm, click on "D
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