"A great milestone would be to get two nanofingers together so you can pick something up," he said. "So far the image you get of the [scanning tunneling microscope, the device used to manipulate atoms to spell IBM] and these local-probe things is that you've got a finger and you're moving it around on a table and moving it up and down. In fact a better analogy is your elbow, something that's not long and skinny but is big and fat.
"I think that a buckytube being the probe of an STM would be a help, probably even qualitatively a help, but the big breakthrough will be to get two of them so you can oppose them, like Chinese chopsticks. It's like the development of the opposing thumb, to pick things up. We have no way right now of picking something up by holding it between two things. The opposing thumb would be a major advance."
Conceivably, it would take us one step closer to the Great Nano Future as envisioned by Eric Drexler.
Drexler had worked out an entire argument, a proof, that the nanotech revolution could hardly be avoided. Premise one was the "multiple pathways" point, the observation that there were many distinct alternative routes, all of them leading toward the fabled assemblers.
There was, for example, the protein-engineering pathway, where you'd construct an amino acid sequence that would fold up into the shape of a molecular machine, or at least into the shape of a lesser component. Or, there were now a bunch of probes with which you could position atoms exactly where you wanted them, to gain the same result. And finally there was the self -assembly route, where you'd design molecules to have such shapes and bonding sites that they'd fit together precisely, lock-and-key fashion, to produce a functional device.
Premise two was that there were rewards and payoffs at every step of the way, along each of the various routes. And you could reap those rewards quite aside from the goal of creating a molecular manufacturing technology. You didn't have to be a believer in the greater Drexlerian vision.
And then finally, when those various techniques and pathways had been refined to the point where the goal of molecular manufacturing was actually within reach, nanotechnology would appear as a huge and attainable boon; this was premise three. The lure of it all would be too powerful to resist.
In fact, each of Drexler's "multiple pathways" was soon marked off with a row of new nano-milestones. Researchers had, for example, come up with ways of incorporating "unnatural" amino acids into proteins. The proteins of all living things were combinations of naturally occur ring amino acids, but there were only 20 different naturally occurring amino acids whereas some 60 or more were chemically possible. Soon enough, scientists had figured out ways of getting the cells to produce "unnatural" amino acids, substances they were never meant to build.
It was wonderful news to nano fans, who saw a whole new range of possibilities opening up in front of them.
But if nature's amino acids were entirely dispensable, then why not the proteins them selves? Maybe you could have a protein substitute, a mock protein, an alternate material that you could engineer and fool with to your heart's content.
Now, any calm and skeptical reader might have seen this as yet another case of "science fiction" gussied up as science, but a few years after Drexler had predicted it, even that rather farfetched item had actually been invented. In 1993 researchers at the University of California, Berkeley created an analog polypeptide (a substitute protein, essentially), called an oligocarbamate. This new substance had a molecular backbone and side chains just like conven tional proteins did, but it was made out of slightly different materials, ones which had the added attraction of being both stiff and highly controllable. In short order, the inventors had developed a "library" of some 256 oligocarbamate structures.
So now there were these substitute proteins to work with. A whole new pathway!
And then, suddenly, there was the "artificial atom."
This was so bizarre an invention that neither Drexler himself nor, very probably, anyone else, had ever even remotely anticipated it. How could there be an artificial atom? But Raymond Ashoori, a physicist at AT&T Bell Labs, had created onean atom whose electron count was controllable by its human maker, from zero to 60.
The "atom" in question was actually an empty space within a gallium arsenide crystal to which electrons could be moved one at a time by the application of a light magnetic pulse. In the case of an ordinary, garden-variety atom, electrons were held in place by the nucleus, whose positive charge attracted and bound the negatively charged electrons. In an "artificial atom," by contrast, electrons were held, instead, by an externally imposed magnetic field. But the final effect was much the same: a bunch of electrons whizzing around in a small space.
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