John Clark wrote:
> About 5 years ago I listed 6 reasons why a macroscopic assembler,
> like a person on a assembly line, was doing a far more difficult
> task that requires much more brain power than a Nanotechnology
> assembler ever would. I still think it's true, if it wasn't biology
> wouldn't exist.
Wouldn't it? Couldn't the millions of years of development work on
DNA and the rest of the body have created something that performs a
more difficult job than screwing in rivets?
> 1) The parts a macroscopic assembler uses would be very expensive, the parts
> that Nanotechnology uses, atoms, are very cheap.
True. But buildings are rather expensive also; beams are relatively
cheap. Why don't we just make robots build buildings (or at least
their skeletons) from beams and rivets? Or, more to the point: why is
that substantially harder than building proportionately sized
nano-products?
> 2) A macroscopic assembler must use many thousands or millions of different
> types of parts and it must learn how to use all of them. At the most,
> Nanotechnology uses 92 different parts (the elements) but in the real
> world almost everything we know of is made of only about 20 parts, and for
> life about 10.
You're imagining nanotech operating on a very different level, I
think, from the way most people in the field are imagining it.
Drexler, for example, imagines machine-phase assembly to look an awful
lot like macroscale assembly, as far as the number of parts are
concerned; rather than fill Nanosystems with discussion of how pure
carbon reacts and how we can use that to build complex polymers one
monomer at a time, he fills his diamondoid chapter with sketches of
designs for levers, struts, bearings, rivets, etc.
Why did he do this? Probably because it's a hell of a lot easier to
deal with, computationally speaking, than to try to do it the other
way. "Chunking" the problem like this helps to REDUCE the complexity
of the problem, rather than to increase it.
> 3) All the many different parts a macroscopic assembler must use are fragile,
> and fragile in different ways, the machine must learn the proper handling
> techniques for them all or it will destroy the parts before it can use
> them. There is no way you can damage the parts Nanotechnology deals with.
Not true if you chunk the problem the way Drexler does; indeed, he
spends a lengthy section of the book dicussing just when and how his
bonds will break under stress.
But, again, returning to the macroscale building builder; while it's
true that beams can and do break, so can nanoscale beams. This looks
to me like a difference with no difference.
> 4) None of the parts in a macroscopic factory are absolutely identical.
> Despite our best efforts, individual variation still exists, and so we
> must deal with each part slightly differently and compensate for the
> variation in the assembly process if we want the finished product to work
> properly, that often takes intelligence. On the other hand, according to
> the laws of Physics one hydrogen atom is absolutely identical to another
> hydrogen atom and can be treated in exactly the same way. Atoms have no
> scratches on them to tell them apart.
OK, suppose I have a set of beams for you that are identical enough
that slight discrepencies in shape or size are irrelevant. Does this
make the project that much simpler? Why can't we get robots to build
buildings out of perfect-enough beams?
> 5) Nanotechnology can manipulate matter without ever leaving the digital
> domain. You may have to deal with a rod 27 carbon atoms long, or 28 atoms
> long, but you never have to worry about a rod 27.5601334 atoms long.
> A Macro assembler wouldn't have that luxury when it tried to build
> something with an oak log.
Again, suppose the beams are 25 +/- 1% units long; does the
problem really get that much easier?
> 6) Most of the parts a macroscopic assembler use would have to be very
> complex and the ways they interact with other macroscopic parts would be
> even more complex. Think of the windshield of a car, it interacts poorly
> with the engine block, and even with the windshield frame the interaction
> must be managed with great skill or you'll have a disaster. Nanotechnology
> is like building with Lego blocks, you can build structures of arbitrary
> complexity, yet there are only a few different types of blocks and they
> interact with other blocks (bounds) in only a few different ways.
And this? This claim is just wrong. Organic chemistry is
substantially more complicated than Lego blocks, even in the machine phase.
Anyway, think of it this way: if macroscale objects interact in a
complex way, why do you think smaller clumps of atoms wouldn't also?
-Dan
-unless you love someone-
-nothing else makes any sense-
e.e. cummings
This archive was generated by hypermail 2b29 : Mon Oct 02 2000 - 17:34:35 MDT