Drexler challenges opponents of nanotechnology
In a letter published in Chemical & Engineering News, 28 June 2004, p.4, under the title "Nanotech challenge," Eric Drexler called for a dialog on the physical and engineering specifics of proposals to build molecular assemblers. Drexler wrote: "The recent publication of an additional letter to the editor (C&EN, May 17, page 5) regarding the Nanotechnology Point/Counterpoint (C&EN, Dec. 1, 2003, page 37) suggests that readers are still interested in this exchange. To date, although I've heard of scientists who endorse Richard E. Smalley's conclusions, none has been willing to endorse the core of his new argument (that water is essential to controlled chemical synthesis)."
Nanotech challenge
published in Chemical & Engineering News, 28 June 2004, p.4
The recent publication of an additional letter to the editor (C&EN, May 17, page 5) regarding the Nanotechnology Point/Counterpoint (C&EN, Dec. 1, 2003, page 37) suggests that readers are still interested in this exchange.
To date, although I've heard of scientists who endorse Richard E. Smalley's conclusions, none has been willing to endorse the core of his new argument (that water is essential to controlled chemical synthesis). Some of the earlier letters to the editor instead repeated old speculations that a thermodynamic limit might preclude precise molecular manufacturing, but this argument would speak with similar force against the existence of crystals and living systems. Design studies in this area fully reflect such basic principles as the atomicity of matter and the laws of thermodynamics, and the rest of chemistry and physics besides.
Given the ongoing interest in this topic, I (and my colleagues) would welcome an opportunity to respond to informed criticism of the published literature on molecular manufacturing. If the opponents to molecular assemblers can point to specifics and elevate the discussion to one of physics and engineering, this dialogue would present a key breakthrough regarding open, productive discussion of these important issues. Indeed, if our arguments are faulty, this discussion would put an end to such questions in a decisive manner. Otherwise, it appears the questions will center on graphical display conventions.
If no opponents present themselves, then perhaps an article covering recent and past progress in mechanosynthetic modeling would advance the discussion.
K. Eric Drexler
Palo Alto, Calif.
July 8th, 2004 at 7:18 AM
Non-water based chemical synthesis
It would seem there should be at least 4 places that one could look for non-water based chemical synthesis.
First, geological processes that take place in deserts. Either on Earth or on Mars. The problem is determining that the chemical processes are recent (i.e. did not occur when significant amounts of water may have been present) and could be driven by sources of energy such as wind driven molecules or solar radiation. In these cases reaction rates may be low but one could still have detectable chemical reactions taking place due to the amount of surface area involved.
Second, underground geological processes in environments which are too hot for water to be present. In these cases heat and pressure would be energy sources.
Third, vacuum based chemistry. I know there are chemical reactions where one goes to lengths to exclude the presence of water. I suspect there is already some body of literature about chemical reactions taking place in other solvents as well as in a vacuum. Of course it would be interesting to design experiments involving vacuum chemistry and get them to be studied on the ISS. It would then be hard for Smalley to duck the results.
Fourth, space based chemistry — i.e. what molecules have been detected in interstellar dust and gas clouds that are extremely unlikely to have been formed in either stellar explosions and could not be formed using water based reactions (such as on or in comets).
July 8th, 2004 at 7:40 AM
Look in the organic chemistry laboratory
> It would seem there should be at least 4 places > that one could look for non-water based chemical synthesis. Add at least one more: organic chemistry laboratories. A very large number of organic reactions take place in nonaqueous environments to accomodate nonpolar reagents which are insoluble in water. Diethyl ether, THF, ketones, benzene, chloroform, and many other solvents prove conlusively that chemistry can happen in, and indeed may require, places without water.
July 9th, 2004 at 10:05 AM
Re:Look in the organic chemistry laboratory
Good point. It would seem that in some (most?) cases the solvent primarily exists to allow molecular motion to bring the molecules into proper orientation to allow the reaction to occur. That would suggest that you could also perform the reactions in a gaseous state. Are there any good examples of reactions where the reactants themselves form the gas or there is a gas "solvent"?
Now of course if the only use of the solvent is to allow rotation of the molecules into proper orientation and/or provide them with some net velocity when they encounter each other (pressure) then it would seem to me that those qualities are unimportant when one considers mechanosynthesis because the orientation and applied pressure are controlled by the assembler itself.
Now of course there are reactions where the solvent molecules may play a role in the reaction itself but then one must wonder in what fraction of reactions that are commonly used is this the case?
July 9th, 2004 at 11:08 PM
Am I missing something?
Isn't atmospheric chemistry a whole, like, field unto itself? And the atmosphere is mostly gas phase, right? Or is there some more specific flavor of chemical operations in question here and I'm just misunderstanding the point?
July 10th, 2004 at 7:53 AM
Solvent effects
> Are there any good examples of reactions where the
> reactants themselves form the gas
Halogenation of small alkanes; this one should be the most familiar because it is used in every organic chemistry course. Polymerization of ethylene to polyethylene at high pressure is an industrial reaction of some prominence.
> or is there a gas "solvent"?
No; solvent effects can not occur in gas phase because there are not enough molecules of such "solvent" and they are not close enough together.
> Now of course if the only use of the solvent is
> to allow rotation of the molecules into proper
> orientation and/or provide them with some net
> velocity when they encounter each other
The solvent actually hinders molecular movement, and thus is no help in orienting or acceleration molecules. It is however extremely important for stabilization of intermediates; water can very effectively stabilize charged ions and thus aids in dissociation of polar leaving groups.
> Now of course there are reactions where the
> solvent molecules may play a role in the
> reaction itself but then one must wonder in what
> fraction of reactions that are commonly used is this the case?
Quite a few, actually. Proton transfers from and to water molecules is very common; many reactions involving carbonyl groups, for instance, begin and/or end by protonation of the oxygen.
July 10th, 2004 at 10:38 AM
Re:Solvent effects
…solvent effects can not occur in gas phase…
I think one has to be slightly careful here. A mixture of two or more real gases will display mole-fraction-dependent deviations from ideality, e.g. from Dalton's and Amagat's "laws". These are, if you like, "solvent effects". But because gas-phase reactions typically proceed by binary collision, one species does not directly affect a reaction between two others. I think that's what you meant.
July 10th, 2004 at 11:08 AM
Re:Am I missing something?
Thats a good point as well Chip. I am unsure if it occurs very much at familiar atmospheric levels (perhaps 0 to 7 miles) [Though perhaps pollutants like CO or NO might contribute]. But at higher altitudes where one has UV radiation as an energy source one certainly has an extensive variety of chemical reactions taking place. As the whole chlorofluorocarbon experience points out humans can contribute extensively to these processes without realizing it.
But going back to the original article it seems as if Smalley is stuck on the fact that the only "assemblers" can be the ribosome or a series of enzymes (such as those that assemble everything from cholesterol to B-12 to maitotoxin (one of the largest biological molecules). He feels that the ribosome or enzymes are necessary for nanotechnology. I could provide examples of solutions that answer many of his questions but to do a reasonable job would provide doing some research to cite references and that would be a bit longer than I'm willing something I'm willing to attempt this morning.
But his statements "Computer-controlled fingers will be too fat and too sticky to permit the requisite control. Fingers just can't do chemistry with the necessary finesse." and "it would be helpful to all of us who take the nanobot assembler idea of "Engines of Creation" seriously if you would tell us more about this nonaqueous enzymelike chemistry." seem to suggest that he read EoC and decided the entire concept was impossible and has never bothered to read Nanosystems or any papers on mechanosynthesis. He now appears to be grasping at straws to maintain his stated position.
Robert
July 11th, 2004 at 2:16 PM
Re:Am I missing something?
Why is this man Smalley so prideful and unable to just examine the data that men and women such as Robert Bradbury, Eric Drexler, Ralph Merkle, and Chris Peterson have provided, year after year? Is it his own pride that causes him to grasp at straws, as Robert pointed out, or, are there people behind him that have him as a paid debunker? What is this man's problem???
July 11th, 2004 at 6:05 PM
Silence the critics
The best way to silence the critics is to make a complete design for an MNT system and provide and open source simulation platform. The only argument that holds any weight is "how are we ever going to build that?" Providing a working simulation won't fix that but at least it will silence the critics who claim that a working system is not theoretically possible.
July 12th, 2004 at 8:27 AM
Re:Am I missing something?
Don't forget Robert Freitas, Chris Phoenix, Will Ware and others who have made significant contributions to the far sighted vision. And then there are probably several dozen who have contributed significantly from a nearer term perspective.
I don't think the MNT critics (pundits?) are being paid. I think they generally believe what they say. I think the major problem is that they have not taken the time to investigate the serious literature. This may be a typical situation for most people who have higher(?) positions. This was very clear at the NIH Nanomedicine Roadmap meeting in May 2004. I would be very surprised if more than 5% of an audience of 300-400 people (including several NIH Institute directors) had read either Nanosystems or any of the Nanomedicine volumes. That in large part is probably due to time constraints related to their job responsibilities.
It may also be the case as Christine Peterson suggested in the April 2004 letter to Foresight Inst. Senior Associates, "We believe we understand the motivation behind it — fear that discussion of MNT may somehow negatively impact shorter-term nanotech research, either by redirecting funds toward MNT or by reducing the total amount due to supposedly-negative public reaction to MNT." (Where the "it" being discussed is efforts by some groups/organizations to discourage research into or the promotion of subjects such as molecular manufacturing and/or nanorobots.)
July 12th, 2004 at 8:45 AM
Re:Silence the critics
There will still be lots of people whose expertise lies in the actual manipulation of atoms and molecules who will not accept a simulation. They will claim that simulations are based on approximations (which they generally are). It is rare that you find people who understand the theoretical & computational & experimental realms sufficiently that they can feel comfortable with what each realm is able to "prove".
You also leave out the cost issues. Even if you have a valid simulation and can invent a valid assembly path you still have the problem that if it costs too much to produce a usable concrete result then the effort is rather pointless. As Robert Freitas pointed out in his recent interview, "Each nanorobot design may require huge design teams of thousands of technical people" so one is talking something like $100M-$1B per nanorobot design (this may not include the cost of designing an assembly process or the cost of the components necessary to manufacture all of the parts contained in a nanorobot). Yes, I realize in the final analysis those costs get amortized over billions of people. But the gap between starting with nothing and that final level of justification is quite large.
July 13th, 2004 at 5:28 AM
Re:Solvent effects
Wouldn't most forms of chemical vapor deposition qualify?