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Nanotechnology: Are Molecular Assemblers Possible?
Roland Piquepaille writes "Two experts in the field of nanotechnology, K. Eric Drexler, Ph.D., cofounder of the Foresight Institute in Palo Alto, Calif., and the person who coined the term "nanotechnology," and Richard E. Smalley, Ph.D., a professor at Rice University and winner of the 1996 Nobel Prize in Chemistry, exchanged open letters about "molecular assemblers" -- devices capable of positioning atoms and molecules for precisely defined reactions in almost any environment. These letters are making the -- long -- cover story of the current issue of Chemical & Engineering News. At the end of this rich exchange of four letters, they still disagree about the issue. Drexler thinks "molecular assemblers" are possible while Smalley denies it. Who is right? Don't count on me to give an answer. This summary contains some forceful quotes from the original letters."
No matter how unlikely it seems, I think you have to be very careful saying something is impossible. Especially something that we are only just starting to explore - such as nanotech.
What a ridiculous assertion. It is most certainly *not* illegal to build any car from parts, or even to make one car look like another.
There is an entire 'kit car' industry, you might want to go have a look at it.
Try to make a C compiler out of C while you are at it. Oh yeah...Already done!
As Dexter quotes Smalley:
Molecular assemblers are not currently possible so we're not discussing 'now'. As for the future, well anything is possible. Look back through history and I don't think anyone can seriously say that anything is impossible given a long enough timespan - given enough research and progress and time, humans will probably find ways to overcome any physical, chemical, biological etc limit.
So if the future is certain, then all these discussions are about is when. Given the lack of developments in the nanotech area, i doubt anyone can give an accurate timeline as more research/developments is required.
Therefore the whole discussion seems like a pissing contest since neither side can really provide any solid info to predict when their predications will become true.
If I had to bet, I'd say that Drexler was right. Smalley seems to rely on strawman arguments (they'd be restricted to water) and arguments from incredulity (the fat fingers schtick). This is the same sort of plausible sounding arguments that have been used to "prove" (in my lifetime) that we will never detect planets around other stars, that we will never be able to image individual atoms, that I will never have a hi-res colour display on my desk, that we will never be able to clone a mammal, etc., etc.
If you strip away the fancy words (and shamelessly simplify), this becomes much more obvious:
Drexler may well be optimistic about the timeline, and may well be underestimating the difficulties, but I've yet to see an argument that it can't be done that holds up under critical examination.-- MarkusQ
Your body does what you've described all the time using DNA as the storage device, and only a two-part complex to do the actual assembly (ribosomes). One problem is, there we're talking about assembling from a fairly well defined set of components which are themselves complex enough to have ways of being selective (an amino acid of a particular geometry will bind preferably to a particular other structure). When you're talking about single atoms, there isn't that much of a geometric factor acting in your benefit anymore. Of course, we even manage that somewhat, since there are particular proteins in our body which end up having a single metal ion of some type or other in the center of them (hemoglobin - iron, chlorophyll - magnesium). The question is, can we generalize this and make it externally controllable (i.e. we feed the DNA-equivalent in by some remote process that preferably doesn't involve changing the environment we're building in).
In the body, communication is usually done diffusing some chemical species that the other cells react to. So perhaps there'd be a byproduct of what one robot is building, and the others would be designed to be able to detect that byproduct to measure the local status. You should be able to build fairly complex uniform structures just knowing the local environment (periodic structures like crystals or networks), but it'd be difficult to build a single highly specified structure unless you used some other control mechanism with good spatial resolution, like in chip manufacture.
Yes, they are possible. Look at what living cells already do ... every single one of them. They convert raw materials into cell structures. We already know it's possible; we just need to figure it out how to do it our way, or copy the way the cells do it.
Cyde Weys Musings - Scrutinizing the inscrutable
Ferrari Inc. would then copyright the design of the car and include a license with your friend's Ferrari.
If you're using a molecular assembler to copy the ferrari, you could use it to copy the license certificate, which would be an exact duplicate so unrecognisable from the original.
Even if they register licensees, you just copy your friends passport (after instructing the assembler to change the photograph) so you can 'prove' you are $FRIEND and you're the legitimate licensee.
However, if molecular assemblers ever become mainstream I'd rather design my own car and let it assemble that. If everyone is driving a Ferrari I'd rather have something different.
By your logic we don't exist. After all, how could a human have been born without a human to bear it?
;) ).
But good job on restating the chicken and egg problem in an obscure way.
The first molecular assembler can be built "by hand", just like the first robots were. We've already got the capability to shove around individual atoms (remember IBM spelling out "IBM" with Xenon atoms?), so it's at least theoretically possible (as long as we only need Xenon atoms to build it at least
No offense, but what idiot thought to use 2.4ghz inside the body?
Yes, of course it barely transmits, 2.4ghz is the frequency used by microwaves to heat food, because water absorbs it so well.
Hint: We're mostly water too.
Now if we could just dessicate people utterly, those transmitters would work just fine...wouldn't be much of a life monitor, though...
--Dan
You can't just say "well, this works with an iron atom in a hemoglobin molecule, so let's make a different carrier molecule with the same geometry, put it on a robot arm and use it to collect up nickel atoms, or whatever". Biology works because over billions of years a limited group of reactions has been found to work on a limited range of materials, in bulk and in carrier liquids. The notion that this means you can just build little tiny cranes and waggle atoms around does not follow.
Let's see how well that argument stands up in paraphrase:
No one is suggesting that we would blindly copy the geometry of some biological mollecule (without regard to it's charge distribution, orbital occupation, potentials for resonences, etc.), attach it to a robot arm, and expect it to do the job, any more than we would build an airplane by glueing birds wings on a school bus.The whole biological-existence-proof line of arguments came up because some people (including Smalley, IIRC) claimed that building macroscopic objects out of components assembled with atomic precission was impossible in principle. Life forms are a clear concrete example of something that is build in exactly that way.
Now, saying that birds exist does not tell you how to build an airplane (though birds might be a good place to look for hints); all it does is shoot a big hole in the argument that flight is impossible.
-- MarkusQ
"From reading the letters I don't think Drexler has really addressed the problems raised by Smalley fingers at all, he just tries to brush the problems aside"
If you'd read the letter a little more closely, you would have seen that Drexler didn't address the problems with those 'sticky fingers' because he'd thought of the problems a long time before smalley, and had thus dismissed that idea a long time ago.
The worrying thing is that Smalley found it necessary to use an already dismissed idea as a straw man to try and make Drexler look bad. Not very scientific. And certainly not conductive to the advancement of science.
From other's (I'm neither a physicist, chemist or biologist) reactions on Smalleys technical arguments, I gather that his understanding of proteins is 20 years outdated, since that's how far back it was proven that proteins can function outside of water.
Biology works because when it found one reaction that worked, it stuck with it and developed it further. If something is not demonstrated in biology, that doesn't mean it can't exist. Conversely, if something is demonstrated in biology (and as Drexler argues, that is true for molecular assemblers), we know it's possible.
The idea of a making and breaking chemical bonds with molecular precision has already been demonstrated. That it won't work with every combination of molecules is a given. But then, it's very difficult to drive a nail into a wall if your hammer is knitted out of wool, and the nail made of rubber.
The bottom line in this debate is that Drexler, and with him many others, believe this is a promissing direction for research. Unfortunately, Smalley is the one holding the purse (he's with the NNI), and doesn't want any research in that direction.
Drexler talks about being prepared, Smalley about not worrying the children. Regardless of who is right on the science side, what do you think is the wiser decision?
By this time it will not be possible to buy a Ferrari, but only to license a copy.
Buy with what money? When you can replicate all the food, clothing, shelter, weaponry, medicine, entertainment, and all the general goods you will ever need, what, exactly, is the point of money? Without scarcity, money ceases to exist in ALL it's forms... With a replicator, the entire CONCEPT of economics will go the way of the feudal system; just another quaint idea you can read about in your replicated bookery.
I'm sorry, that's irrelevant. That's like saying someone told a false statement because he's a Republican. (Take your pick on insult you'd like to throw.)
I could be a bum on the street and still tell you the correct science. You might not believe me, but it's still correct.
As for Mr. Drexler, I've read Nanosystems. Mr. Drexler doesn't know chemistry. If he did, he could tell me all the cool new reactions we need to create the stuff he proposes. Or the chemistry/physics needed to do a nanoassembler.
I've done plenty of computational chemistry research--it's about 90% of my Ph.D. And you know what? I can happily draw whatever molecule I want on the screen and predict the properties. Can I make it?
NO, not necessarily!
There's a reason a lot of people hate orgo class in college. Chemistry is tough--there are a lot of exceptions and the best synthetic chemists have years upon years of experience in lab bumping their heads against walls trying to make things.
Drexler needs to try some synthetic chemistry. Maybe then he'll rethink his nanoassembler idea.
No, chemical reactions don't happen like that. Molecules do not randomly appear in product positions, nor do they follow nice straight lines to form products. They follow complicated, n-dimentional reaction coordinates involving deformations of both product and reactant. Drexler mumbles something about mechanical arms and ignores this point. Using a different name for something that is functionally identical to a "Smalley Arm" does not mean that you can cavalierly ignore all the problems which have been shown to exist for a "Smalley Arm".
A disclaimer: www.jetpress.org is the website of the Journal of Evolution and Technology, published by the World Transhumanist Association. Upon skimming the contents, it's more like a cultural studies journal like Social Text than a scientific journal like Physical Review, so it may or may not be correct about all the scientific details.
"It take 9 months to bear a child, no matter how many women you assign to the job."
Money will still have value. Someone has to create and/or design food, clothing, medicine, entertainment, etc. Money will buy what it has always bought - what is valuable. Over the last hundred years, we've gone from paying primarily for the stuff that makes up things, to paying primarily for people's time to manufacture things (i.e., labor is now more expensive than material). This would just complete that cycle.
Sometimes the truth is arrived at by adding all the little lies together and deducting them from all that is known.
What we have here are two different worlds colliding. Drexler is coming at this from the point of view of a theoretical physicist, while Smalley is an experimental chemist.
Drexler has found certain theoretical processes which would lead to molecular assemblers. The key problem comes from his assumption of complete control over the atoms. Despite his assurances to the contrary, you still have one big fat sticky finger which you've attached your strained structure to. He simply sees that it is possible (of course, if you read his books, there is a glaring lack of chemical calculations).
Experimentally (I'm a bit biased here, I'm an experimentalist) this is a bunch of crap. No one is anywhere close to doing anything like this. First we need to show experimentally that his idea of creating stressed structures and twisting them apart will work, and no one can touch that right now. How do you create the strained structures? In addition, this would have to be done in vacuum to keep interactions with the environment at a minimum. It would also have to be done at cryogenic temperatures to keep the atoms from vibrating out of place (remember we're relying on two unstable structures). This leads to an expensive and difficult proposal.
There are a few groups (I know of Wilson Ho's group at UCI - great pictures by the way) which are working on joining one atom with another. It's done under extreme conditions inside a scanning tunnelling microscope, and it's VERY hard. They don't do any twisting, they do the sensible thing and use applied voltages to excite and bind atoms.
Quite frankly, Feynman and Drexler have been major impediments to experimental nanotechnology for a long time now. There are plenty of interesting, self-assembled structures out there that can do some amazing things which are not related to the assembler idea. There are plenty of good research groups which are dismissed funding in favor of groups which are flailing around in the dark.
The first thing you learn about nanotechnology is that any intuition about the macroscopic world doesn't carry over. Trying to fit our notions of the rest of the world into the nano-scale world is foolish and wrong. Those strait lines between atoms in a molecule are not always strait.
Before we try to use nanotechnology to shape the future we need to understand it. Drexler gives the impression that we already do, and that it's time now to move foward, but no one knows how yet; we just don't understand.
I think it would be wrong of us to say that molecular assembles are impossible. Personally, I think it is possible, and that's why I do this. But to say that they are "close" or to give ANY prediction of when we will see them is just silly. After saying that, let me say something silly and say that although I hope to see nanotechnology come of age in my life, I don't expect to.
But that's just my point of view - I dislike Drexler's constant reference to Feynman, his total lack of any experimental pedigree, and his unwillingness to take on board the views of those who actually know a bit about what he spouts off about, because they have tried it.
Reading the article, it seems that Drexler in his second letter ignores the fact that he is contradicting what he says in his first letter, because the mechanisms proposed in the second would inevitably require the very same 'Smalley fingers' that he derides in his first polemic.
Drexler is just pissed that someone with credibility and experience has pointed out the holes in his arguments, and cast doubt on his percieved achievements (which are roughly on a par with other Sci-Fi authors, IMHO).
Leave it to guys like Smalley - we'll end up with nanotechnology that works - maybe not the grand self-replicators in the first iteration, but at least we'll have technology rather than the PR puff and self-publicity that characterises Drexler's current output.
Sorry for the rant, but Drexler really, really pisses me off.
oh brave new world, that has such people in it!