Microsoft Word Kurzweil, Ray The Singularity Is Near doc

Fat and Sticky Fingers 
In the wake of the rapidly expanding development of each facet of future nanotechnology systems, no serious flaw in 
Drexler's nanoassembler concept has been described. A highly publicized objection in 2001 by Nobelist Richard 
Smalley in 
Scientific American
was based on a distorted description of the Drexler proposal;
92
it did not address the 
extensive body of work that has been carried out in the past decade. As a pioneer of carbon nanotubes Smalley has 
been enthusiastic about a variety of applications of nanotechnology, having written that "nanotechnology holds the 
answer, to the extent there are answers, to most of our pressing material needs in energy, health, communication, 
transportation, food, water," but he remains skeptical about molecular nanotechnology assembly. 
Smalley describes Drexler's assembler as consisting of five to ten "fingers" (manipulator arms) to hold, move, and 
place each atom in the machine being constructed. He then goes on to point out that there isn't room for so many 
fingers in the cramped space in which a molecular-assembly nanorobot has to work (which he calls the "fat fingers" 
problem) and that these fingers would have difficulty letting go 'of their atomic cargo because of molecular attraction 

---

forces (the "sticky fingers" problem). Smalley also points out that an "intricate three-dimensional waltz ... is carried 
out" by five to fifteen atoms in a typical chemical reaction. 
In fact, Drexler's proposal doesn't look anything like the straw-man description that Smalley criticizes. Drexler's 
proposal, and most of those that have followed, uses a single "finger." Moreover, there have been extensive 
descriptions and analyses of viable tip chemistries that do not involve grasping and placing atoms as if they were 
mechanical pieces to be deposited in place. In addition to the examples I provided above (for example, the DNA 
hand), the feasibility of moving hydrogen atoms using Drexler's "propynyl hydrogen abstraction" tip has been 
extensively confirmed in the intervening years.
93
The ability of the scanning-probe microscope (SPM), developed at 
IBM in 1981, and the more sophisticated atomic-force microscope (AFM) to place individual atoms through specific 
reactions of a tip with a molecular-scale structure provides additional proof of the concept. Recently, scientists at 
Osaka University used an AFM to move individual nonconductive atoms using a mechanical rather than electrical 
technique.
94
The ability to move both conductive and nonconductive atoms and molecules will be needed for future 
molecular nanotechnology.
95
Indeed, if Smalley's critique were valid, none of us would be here to discuss it, because life itself would be 
impossible, given that biology's assembler does exactly what Smalley says is impossible. 
Smalley also objects that, despite "working furiously, ... generating even a tiny amount of a product would take [a 
nanobot] ... millions of years." Smalley is correct, of course, that an assembler with only one nanobot wouldn't produce 
any appreciable quantities of a product. However, the basic concept of nanotechnology is that we will use trillions of 
nanobots to accomplish meaningful results—a factor that is also the source of the safety concerns that have received so 
much attention. Creating this many nanobots at reasonable cost will require self-replication at some level, which while 
solving the economic issue will introduce potentially grave dangers, a concern I will address in chapter 8. Biology uses 
the same solution to create organisms with trillions of cells, and indeed we find that virtually all diseases derive from 
biology's self-replication process gone awry. 
Earlier challenges to the concepts underlying nanotechnology have also been effectively addressed. Critics 
pointed out that nanobots would be subject to bombardment by thermal vibration of nuclei, atoms, and molecules. This 
is one reason conceptual designers of nanotechnology have emphasized building structural components from 
diamondoid or carbon nanotubes. Increasing the strength or stiffness of a system reduces its susceptibility to thermal 
effects. Analysis of these designs has shown them to be thousands of times more stable in the presence of thermal 
effects than are biological systems, so they can operate in a far wider temperature range.
96
Similar challenges were made regarding positional uncertainty from quantum effects, based on the extremely 
small feature size of nanoengineered devices. Quantum effects are significant for an electron, but a single carbon atom 
nucleus is more than twenty thousand times more massive than an electron. A nanobot will be constructed from 
millions to billions of carbon and other atoms, making it up to trillions of times more massive than an electron. 
Plugging this ratio in the fundamental equation for quantum positional uncertainty shows it to be an insignificant 
factor.
97
Power has represented another challenge. Proposals involving glucose-oxygen fuel cells have held up well in 
feasibility studies by Freitas and others.
98
An advantage of the glucose-oxygen approach is that nanomedicine 
applications can harness the glucose, oxygen, and ATP resources already provided by the human digestive system. A 
nanoscale motor was recently created using propellers made of nickel and powered by an ATP-based enzyme.
99
However, recent progress in implementing MEMS-scale and even nanoscale hydrogen-oxygen fuel cells has provided 
an alternative approach, which I report on below.