Nanotechnology: Are Molecular Assemblers Possible? 513
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."
Well... (Score:2, Insightful)
Re:Raises interesting questions (Score:2, Insightful)
You can already be arrested for making a copy of your friend's ferrari -- they've got copyright in the design of the car, after all.
Never say never (Score:3, Insightful)
Re:Raises interesting questions (Score:4, Insightful)
There is an entire 'kit car' industry, you might want to go have a look at it.
Re:I can see what the problem might be (Score:5, Insightful)
These discussions are almost irrelevant ... (Score:4, Insightful)
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 (Score:5, Insightful)
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
Re:I never understood how it was supposed to work. (Score:4, Insightful)
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 (Score:5, Insightful)
Re:Raises interesting questions (Score:5, Insightful)
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.
Clarke's first law (Score:1, Insightful)
but if he says that it is impossible he is very probably wrong.'
Arthur C. Clarke
Re:I can see what the problem might be (Score:5, Insightful)
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
Re:Tinkering with nature (Score:5, Insightful)
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
Comment removed (Score:3, Insightful)
Re:Well, I read the letters (Score:5, Insightful)
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
Re:If I had to bet (Score:3, Insightful)
>lifetime) that we will never detect planets around other stars,.... etc....
I see this argument all the time and it's totaly falacious. In my lifetime scientists have claimed that artificial inteligences will be so far superior to human inteligences that they will rule the world for us. When would this occur by? Well according to some 1960s AI pioneers, we'd be ruled by AIs by the 1980s.
Meanwhile in 2003 we're still waiting for someone to even come up with a very rough architecture for building even a simplistic geenral purpose AI, let alone start the practical work of programming one. The same goes for nanotechnology. It's all handwaving, the nano pundits can't put forward any kind of actual theoretical design for a universal contsructor.
Think of it this way. we're much better a building human scale robots, computers and machinery than nano scale ones. therefore a human scale or bigger universal constructor should be many orders of magnitudes easier to make than a nano scale one. Whn wa sthe last time you saw plans for a fully automated, compuetr controlled, humanless factory capable of creating any product, including a copy of itself?
never, precisely. If we can't build one at all, or even come up with rough plans for one, what makes anyone think a nano scale version is any more practical?
Simon Hibbs
Re:Well, I read the letters (Score:5, Insightful)
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?
Drexler did WAY more for nanotech (Score:2, Insightful)
Re:Raises interesting questions (Score:5, Insightful)
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.
Re:Well, I read the letters (Score:5, Insightful)
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.
Re:If I had to bet (Score:3, Insightful)
But the problem is this--Drexler's theory is that we can make an arbitrary object. That's not necessarily true from biochemistry. There are a great diversity of molecules made by nature. But synthetic chemistry has been able to make molecules never made by nature.
Does that mean we can use biochemical techniques to assemble macroscopic assemblies? No.
The trick that life uses is called "self assembly." We haven't the least clue how proteins form 3D shapes from their constituents. It's a great unsolved problem in biology and chemistry. The first one to solve it wins at least ONE Nobel prize.
From current research, we know that we cannot self-assemble every molecule we can imagine. Some will self-assemble and some different types of assemblies are possible. But we're still a *long* way from being able to assemble an abitrary combination--which Drexler requires.
And if you resort to what life can do, we're quite limited. Has life ever made a skyscraper?
Re:Well, I read the letters (Score:4, Insightful)
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".
Re: Existence proof (Score:2, Insightful)
The biotic existance proof proves it's not impossible, but doesn't prove that general materials assemblers are possible, due to the limitations of water chemistry. (I don't count humans as a general nanoassembler; not cost effective.)
It really is quite simple... (Score:3, Insightful)
The smallest self-assembler is equivalent in size to the smallest microorganism. Nanotech devices cannot do better than the already extant nanotech devices: all the enzymes and proteins in a cell (any cell, any virus, any bacterium). Not a single enzyme or protein in any cell anywhere is capable of reproducing itself from first principles (atoms). Even the small "self-replicating" prion protein cannot make itself from scratch. It requires a premade template protein assembled by ribosomes using instructions provided by RNA which was produced by RNA polymerase, which is itself a copy of a DNA "library" generated by an evolutionary decendent of RNA polymerase called DNA polymerase.
The closest thing to a self-assembling "machine" would be the hypothetical self-replicating RNA molecule of primordial, pre-life earth. The presumed precursor to all things living today. But you don't get much use from a self-replicating RNA except more copies of that RNA, which doesn't even do anything but copy itself. It cannot be a universal replicator. Nothing can. Information takes space. All the information needed to replicate the smallest possible item, a prion, is exactly the size of a prion - and it doesn't do anything de novo, just refolds an already extant protein generated by the minimum-sized machinery necessary to generate that protein. Thus a virus could be considered a measure of the smallest possible self replicant capable of producing complex systems (the virus).
But wait! A virus CANNOT be the smallest possible self-replicator. It REQUIRES a pre-existent cell with all the machinery necessary to start from first principles (atoms and small molecules) and generate more complex "machines" and structures. Thus a virus is not, and can not be considered self-contained anymore than a prion can. No, a full-blown cell, the smallest being independently replicable bacteria, are the smallest possible self-replicator starting from first principles (atoms and molecules as a source of building material). Drexler, not being really versed in anything beyond simple chemistry and physics sees things through rose-colored glasses, and ignores the facts around him.
If a self-replicating, autonomous nano universal replicator were actually possible, it would have won evolutionarily as the most efficient replicator and it would be the dominant form of replicator on earth. Hmmm...nope, none around here. There isn't even anything CLOSE to such a beastie within ANY living organism of ANY type.
Re:If I had to bet (Score:4, Insightful)
Strawman. The issue is complex components that have every atom where you want it (with perhaps some acceptance of a very low error rate).
Strawman. The proposal is that we should be able to make arbitrary members of a huge class of useful objects, which isn't the same thing at all.
Strawman and argument from incredulity. First, this isn't Drexler's position, and second I see no reason why we couldn't, since trees do it on a regular basis.
Strawman. Ignoring the fact that we do know a great deal about how proteins fold, it doesn't matter since we don't need to understand the details anymore than the Wright brothers needed to understand how bird poop in order to build an airplane.
Argument from incredulity / ignorance (we don't know how to do it, therefore it can't be done) and Strawman.
-- MarkusQ
Re:required reading (Score:4, Insightful)
Re:If I had to bet (Score:3, Insightful)
Cells can't make exact copies of themselves and I don't believe a group of cells working together would have any more luck in completing that task.
Exact? No. But functional? Sure. Cells do it all the time. In fact, birds do it. Bees do it. And from what I've been told, even educated fleas do it.
He's arguing that, without breakthroughs in chemistry beyond what we can currently imagine (ie some manner of "enzymes" not dependent on water or some other liquid), any molecular assembler that depends on the exact placement of individual atoms will suffer from tremendous error rates rendering the likelihood of creating a functional product infinitesimal.
Beyond what we can currently immagine? That's an argument from incredulity if I ever heard one. And a silly one, since we easily can imagine such things, and have examples (e.g. in gas phase) that come close to what is needed. As for the yields, the arguments get a little more complicated but it's really more a question of engineering than of basic science. There are all sorts of ways to deal with low yields, and armys of practitioners to apply them.
I think Smalley went a bit far in declaring molecular assemblers impossible
Yes. This is the essence of the disagreement. No one is saying we know how to build them now. But Smalley is (incorrectly, IMHO) jumping from this fact to the conculsion that there is no point in trying since the fact that we don't know how to build them now means that it is impossible to build them ever.
-- MarkusQ
Re:I can see what the problem might be (Score:1, Insightful)
In the universe's instruction set, biological compilers use a small RISC subset of the available instructions (atomic interactions). Not all the instructions may be usable by an atomic compiler, but that doesn't mean the biological instructions are the only ones that will work in any atomic compiler. Drexler's and Smalley's arguments basically boil down to arguments about which instructions are usable and controllable. That's an answer that can only be answered by more research; yet Smalley seems to ignore some of the research already done in this area, which makes his arguments weaker, though not insignificant.
The thing is the analogy is not an existence proof, it's a counterexample that the claimed counterproof is invalid. Which is why you admit a general-purpose assembler may be possible. Um, so what was your point again?
Possible always beats Impossible (Score:2, Insightful)
It may well be that we will use tailored DNA to bootstrap nanotechnology. Cells are already very efficient organisms; perhaps it would be possible to grow them in an artificial matrix, with their DNA programmed so that they would express out nanomachines of arbitrary construction. Or perhaps just parts.
Which is more difficult-- understanding of DNA to the level where that would be possible, or doing it from scratch? My guess would be the former.
Re:If I had to bet (Score:3, Insightful)
Drexler is making handwaving claims that this will be doable, without actualy coming up with a concrete explanation of how it could be done.
Hardly handwaving. [barnesandnoble.com]
If you have specific objections, raise them. But don't call something handwaving just because you haven't read it.
-- MarkusQ
Re:Raises interesting questions (Score:3, Insightful)
Don't forget that land property will still have value in a replicator-enabled society. Energy will also probably need to be purchased.
Drexler is mad scientist (Score:2, Insightful)
Energy source (Score:3, Insightful)
Re:Raises interesting questions (Score:4, Insightful)
from an actual nanoscientest (Score:5, Insightful)
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.
Who to believe? (Score:5, Insightful)
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.
Re:Well, I read the letters (Score:3, Insightful)
Drexler thinks he can ignore all the other interactions to make an unreactive assembler work in a general case,
He most clearly does not. He thinks (and, as I've stated, I think he's correct) that these are engineering problems and not "basic science" problems. No one is saying they can be "ignored" anymore than they would say that things like drag can be ignored when designing an aircraft. But that doesn't mean (as Smalley seems to conclude) that the whole thing is impossible, anymore than the existence of drag makes aircraft impossible.
There are lots of potential unwanted side reactions, just as in any field of engineering, and there are lots of ways to deal with them, just as in any field of engineering. But you'll never get anywhere if all you do is throw up your hands and say "Look, complications! We're dombed to failure!"
-- MarkusQ
Clarkes third law (Score:1, Insightful)