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."

Raises interesting questions

If, in the future, copying physical objects is nearly as easy as copying information on a computer, will corporations lobby to pass laws that make it illegal to do so? In other words, will I be arrested one day for making a copy of my friend's Ferrari?

Re:Raises interesting questions

Ferraris are not IP, so you could copy it freely. However, this would devaluate all Ferraris and would be frowned upon by the company. Ferrari Inc. would then copyright the design of the car and include a license with your friend's Ferrari.

By this time it will not be possible to buy a Ferrari, but only to license a copy. Therefore official Ferrari licenses will be a hot commodity for the wealthy and they will slap licenses on the car windows, the cars however will not become their property.

Of course thieves will see this trend and nab the licenses out of the Ferrari, instead of the car itself, which will be worthless.

Hence you could copy a Ferrari, but what good would it do you, as it wouldn't be yours anyway.

Re:Raises interesting questions

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.

Re:Raises interesting questions

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.

Re:Raises interesting questions

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.

Re:Raises interesting questions

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.

Re:Raises interesting questions

Make sure you run your downloaded design through some kind of malware detector, or you may find that you've just created a duplicate of the goatse guy...

Re:Raises interesting questions

If you're going to copy your friend's Ferrari one atom at a time, you better start now....

They try to come after you

It doesn't need molecular technology. They already try to come after you even today. See this nice (and real) example:

http://www.mb-portal.net/html/news/special/2003_ sl r-pl_us.htm

Some guy from Poland "copied" the new Mercedes SLR, long before the real car hits the market. Mercedes tried to buy it from it to get it off the streets. Because that failed, they sue him.

Marc

Lest we forget

Richard Feynman talked about nanotechnology way back in 1959--before "nanotechnology" was even a word.

It kind of irks me that the person who coins a word gets more credit than a person who talked about the actual process--nearly thirty years prior.

Read Feynman's talk at the Zyvex Web site [zyvex.com].

Re:Lest we forget

Actually, in the above mentioned Feynman lecture, There's Plenty of Room at the Bottom [zyvex.com], Feynman talks about making machines that make smaller machines that make smaller machines that make... you get the picture. From the above lecture:

Why can't we manufacture these small computers somewhat like we manufacture the big ones? Why can't we drill holes, cut things, solder things, stamp things out, mold different shapes all at an infinitesimal level? What are the limitations as to how small a thing has to be before you can no longer mold it? How many times when you are working on something frustratingly tiny like your wife's wrist watch, have you said to yourself, ``If I could only train an ant to do this!'' What I would like to suggest is the possibility of training an ant to train a mite to do this. What are the possibilities of small but movable machines? They may or may not be useful, but they surely would be fun to make.

He was not only talking about nanobiology.

Kurzweil

Also interesting is Ray Kurzweil's comments on the exchange:

http://www.kurzweilai.net/meme/frame.html?main=/ ar ticles/art0604.html

Yum

How long would it take one of these assemblers to make a cup of "Tea, Earl Grey, Hot"?

Re:Yum

The risk, of course, is ending up with something almost but not completely unlike tea.

Especially if your replicator is another fine product of Sirius Cybernetics.

Re:I can see what the problem might be

Try to make a C compiler out of C while you are at it. Oh yeah...Already done!

Re:I can see what the problem might be

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 ;) ).

Re:I never understood how it was supposed to work.

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.

Re:I never understood how it was supposed to work.

Communication and memory may not be as large a requirement as one would think. Like complex action that insects (e.g. ants and termites) are able to perform it may be a case of Self Organization [calresco.org] (haven't read this FAQ yet but it looks close to what I want to get across.)

For a good book check out The Computational Beauty of Nature [mit.edu]). Some tasks can be broken down into very simple repeated actions which simple machines can perform. The beauty of these system is that they require little communication between agents. Merely an awareness of what is around you and a simple list of tasks can create some complecated forms.

From the article:

In lectures and in a September 2001 article in Scientific American, Smalley outlined his scientific objections to the idea of molecular assemblers, specifically what he called the "fat fingers problem" and the "sticky fingers problem."

Aye, this is something that almost all /.ers have had to face at one point or another.

required reading

84-page peer-reviewed white paper on nanofactory. Conclusion: we see no hurdles, predicted time line: 10 years from now we could haave the first operating assembler... http://www.jetpress.org/volume13/Nanofactory.htm

Re:required reading

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.

Love and Molecular Assemblers

I think that I got most of the arguments, but it's hard to take a stand. I especially liked this "counterpoint" quote:

Much like you can't make a boy and a girl fall in love with each other simply by pushing them together, you cannot make precise chemistry occur as desired between two molecular objects with simple mechanical motion along a few degrees of freedom in the assembler-fixed frame of reference. Chemistry, like love, is more subtle than that. You need to guide the reactants down a particular reaction coordinate, and this coordinate treads through a many-dimensional hyperspace.

*sigh* I'm touched.

Also I found it interesting that the usage of Nanotechnology was changed so greatly that the creator of the term accepts the newer phrase 'molecular assemblers' for that process.

It's The Snack Food, Stupid!

Drexler thinks "molecular assemblers" are possible while Smalley denies it.

They are possible, and Twinkies(TM) provide the proof. They are manufactured with absolutely no nutritional value whatsoever, and this is only possible if vitamins and minerals are screened out at the molecular level.

DNA

They say its impossible, but isn't DNA essentially just that, and I'm quite sure some lab recently built a transitor from DNA so I'd say its definatly possible.

Well, I read the letters

I'm not a nanotechnologist but I have had a fair bit to do with the behavior of atoms on surfaces, especially metals. I think that Smalley seems to have a much closer grasp on the real world than Drexler. The idea of a nanobot twisting a pi-bond here and snapping a sigma-bond there seems quite ludicrous; where such reactions occcur in the real world it is because of the properties of the exact molecules involved and is reaction-specific. 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.

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.

Re:Well, I read the letters

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.

Re:Well, I read the letters

The man has a Nobel Prize and you're worried about what school he got his PhD from? Yeesh. And Feynman certainly didn't give Drexler a 'Drexler is always right, even 15 years after my death' card. Why the focus on intellectual dicksizing?

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:Well, I read the letters

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:

You can't just say "well, this works with a bird in the sky, so let's make a different wing with the same shape, put it on a vehicle and use it to fly around, or whatever". Animal mobility works because over billions of years a limited group of structures has been found to work on a limited range of environments. The notion that this means you can just build airplanes does not follow.

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:Well, I read the letters

"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?

My summary

I read Engines of Creation, got all fired up, went back to undergraduate school for a second undergraduate degree in chemistry, and really loved quantum mechanics. But organic chemistry opened up a serious can of kick-butt on me!

So I can read the debate but damned if I can make an intelligent contribution to it. Maybe I can translate it down a little:

Drexler: Yo, machine-phase chemistry is the bomb. We can put atoms wherever we want and make anything we want!

Smalley: No you can't, dork. Atoms are not little balls and bonds are *really* not little sticks. You can't build molecules like tinkertoys.

Drexler: Enzymes do it in nature, therefore it's possible.

Smalley: Well, if you wanna make more better enzymes, great, but enzymes only work in water-based living cells and it's kinda hard to grow a cell phone from organic components.

Drexler: My machine-phase chemistry will be to living enzymes as a metal airplane is to a bird.

Smalley: Whatever. Go do your "machine-phase chemistry" and come back when you've actually built something. Hint: I think it's gonna take you 200 years.

I think Smalley is wrong when he says that it's by nature impossible. And I think Drexler is wrong when he says nature has already provided an existence proof. I think we should get started on those 200 years of work and see what we can do!

Scaring children - classic quote from Smalley

Leading up to my visit, the students were asked to write an essay on "Why I Am a Nanogeek." Hundreds responded, and I had the privilege of reading the top 30 essays, picking my favorite five. Of the essays I read, nearly half assumed that self-replicating nanobots were possible, and most were deeply worried about what would happen in their future as these nanobots spread around the world. [...]

You and people around you have scared our children. (emphasis mine)

So there, Smalley wins, he got scared children into the debate. Only thing likely to win debates better are beautiful women's tears, knockout punches, and defaulting by just leaving the room in a huff.

Never say never

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.

These discussions are almost irrelevant ...

since they discuss developments 'in the future'.

As Dexter quotes Smalley:

... when a scientist says something is possible, they're probably underestimating how long it will take. But if they say it's impossible, they're probably wrong.

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

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: We can build structures with atoms exactly where we want them, within reasonable limits.

Smalley:Your fingers are too big. Any robot you build will have fingers too big. It won't work.

Drexler: We wouldn't use "fingers," we'd use molecules designed for the purpose.

Smalley: I don't see how that could work.

Drexler: Living cells do it all the time.

Smalley: Ah, but they need water to do it. Your nano-things will only work in water.

And so forth...

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:If I had to bet

1. We can make macroscopic objects out of complex components already.

   Strawman. The issue is complex components that have every atom where you want it (with perhaps some acceptance of a very low error rate).

2. Drexler's theory is that we can make an arbitrary object.

   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.

3. Does that mean we can use biochemical techniques to assemble macroscopic assemblies? No.

   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.

4. 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.

   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.

5. 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.

   Argument from incredulity / ignorance (we don't know how to do it, therefore it can't be done) and Strawman.

6. And if you resort to what life can do, we're quite limited. Has life ever made a skyscraper? Strawman.

   -- MarkusQ

Yes they are possible

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.

Cells do it

Ribosomes are essentially molecular assemblers that build proteins out of amino acids using instructions from messenger RNA (originally transcribed from the DNA in the nucleus). So, it's not only possible, your cells are doing it as you read this.

Atom Level Manipulation

Take a look at this:
Here [smalltimes.com]

From the article:
"an atomic manipulation facility, unique in the world. This atomic manipulation facility will enable a new generation of experiments to unfold. It will allow McGill researchers to construct new devices atom by atom, thus developing the science and technology required for future electronic and biochemical systems."

Existence proof.

Of course molecular assemblers are possible. Your body contains billions of them -- ribosomes.

A ribosome (a combination of several large protein molecules) constructs arbitrary protein molecules from individual amino acids according to the instructions on a strand of RNA (copied from DNA). Sounds like a molecular assembler to me.

Now, as to whether they can be made smaller and more flexible than that (nanotech's "universal assembler") is another question -- ribosomes may turn out to be the minimum possible assembler. Or not.

It really is quite simple...

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.

Energy source

OK, lots of people have read "Prey" or one of the other Shiny! Exciting! Books! that talk about the "Gray Goo problem". Simply stated, this is that nanoassemblers which are trained to self-replicate could potentially go bonkers and start turning the entire planet into more assemblers. As Homestar Runner might put it, "That's just ridiculous" -- and yet this is what some people lose sleep over! The reason that nanoassemblers will never be able to replicate in an uncontrolled environment, and therefore will never take over the world, is that they need energy to function. Lots of it. Breaking pi and sigma bonds can be ridiculously expensive, requiring several eV of energy in some systems. Pulling a carbon out of a single-walled nanotube takes over 10 eV. Where does the energy come from? Absent a large and complex digestive system, the assemblers will have to be fueled ahead of time or provided with a simple energy source along with their raw materials. These robots will not be able to find the energy they need to keep going in the wild. That's why Smalley's not worried about runaway nanobots. The extreme difficulty of doing "machine-phase chemistry" is another good reason, by the way -- assuming machine-phase chemistry is even possible, how are the nanobots supposed to create a clean enough environment to do their work in the wild? If machine-phase chemistry can be accomplished at all, it will be a much more complicated affair, I think, than Drexler would have us believe.

I side with Drexler.

I read the letters, and skimmed Drexler's "Nanotechnolgy: ..." book.

I think Smalley's argument is that for a specific reaction between two molecules, you need something like an enzyme designed specifically for that reaction. The number of possible molecules is astronomical, and the number of pairs astronomical squared.

I hear you can treat most of molecules mechanically except for a few dozen atoms surrounding the reaction site. That limits it to, let's say, 2^^30 possible molecules, so 2^^60 reactions you need specific enzymes for. Designing any one of those 2^^60 enzymes or reaction paths is feasible. Making an index iwth 2^^60 entries is feasible, given atom-scale memory, although it isn't microscopic. Drexler suggested such an index for diamondoid struts of different sizes in "Nanotechnology: ...". Nanotech is going to make heavy use of indexes like this. Storing all those enzymes, and shipping them one after another to the right place, is going to be SLOW. I suppose you could pipeline your enzyme fetches.

The real number of enzymes needed is much smaller than 2^^60. To get a self-assembling molecule, assuming you feed it the right basic building blocks, you don't need a universal assembler. DNA limits itself to 4 molecules with a single type of connecting part. Proteins limit themselves to 24 molecules (I don't know if the connecting parts are standardized but I suspect they are). Ribosomes can construct ribosomes, so we already know self-assembling machines are possible.

An interesting question is, given an assembler that knows how to do some fixed set of assemblies, what can be built? How big a set is needed? The smaller the set, the less work is needed to get the correct configuration for each reaction. Perhaps we need specialized factories for some building blocks with standard connectors, then just a tape-reading assembler that can connect standard connectors? Standards simplify things.

from an actual nanoscientest

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.

Nanotechnology timeline

A while back, Sean Morgan did the most interesting work [archive.org] I've seen on a timeline and prerequisites for Nanotechnology. At present, odds [ideosphere.com] are that we'll see an assember sometime around 2022.

My Nano Assembler design

Apparently my design for a molecular assembler is deemed impossible for the sticky or fat finger aspect, but I need help understanding why this is impossible. I think I can circumvent that problem.

Anyways here's the design. It is simple and achievable. It is not conducive to building/replicating itself easily though.

The core is an STM microscope-like device, with many parralel tips each working on its own square millimeter (or smaller) area. Needle Tips or fingers doped with the next mollecule (properly oriented) to be inserted move along a conveyor belt where each are inserted into one of the parallel heads, the head then sticks the molecule in place, then the needle is sucked out, and sent to be refilled.

I don't really have a process for making mollecules, and placing them in the proper orientation on a needle.
The one good thing about this design, is that there probably exists a needle material than can react "properly" with any given mollecule, such that it can 1) capture it, and 2) release it. (One method of releasing could just be to jab the needle quickly forward, flinging the package into place).

There's one problem with Drexler's universal assembler theory, with little publicity, that is only partially solved by my design. There is not an infinite number of universal assemblers created instantly, and as a secondary problem, programming them to work and move around cooperatively is not easy, and increases their required size if only because of the massive cpu they need to operate with.

The Other issue only partially addressed is speed. If everything is built using 3d tetris-like merging of 10nm building blocks (mollecules), then finishing a square milimeter takes 10B blocks. A quadrillion blocks makes a cubic milimeter of something. Even at 1 billion blocks per second, it takes 11.5 days to make 1 milimeter thick object. The billion blocks per second seems outrageously high to reach, but another way to increase throughput (but increase congestion of feeder needles) is to have denser parallel heads. If each head works on a square micrometer area, then building a cubic micrometer object takes 1 million 10nm blocks. At (only) 100K blocks per second, a 1mm thick object takes 10,000 secs = 2.77 hours

There's one other big problem. Like building a house of cards on an uneven surface, mollecules won't necessarily maintain a desired orientation without simultaneously placing adjoining molecules to couterbalance them. Seems like there would be a solution to this, with all the arms in such close proximity, but it would also slow down the process.

Who to believe?

I'll take the Nobel prize winning chemist, with a track record of experimentation and success, over the self-aggrandising bullshit artist who has produced nothing but dead trees and wild ideas for the last couple of decades.

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.

For now, Smalley is right.

From the exchange, Drexler gives the impression that matter at the atomic scale behaves in the same way as matter on the macroscopic scale that we live in.

Physicists and chemists would know that this assumption is false. The Dalton theory of atoms as billiard balls has been refuted a long time ago.

How is a mechanical manipulator going to "grab" another atom? These manipulators are also at the atomic scale! Duh.

Today near the bottom of the http://www.foresight.org/ website, it shows a unrealistic graphic of one of Drexler's proposed nanofactories. There are what appears to be spherical atoms being manipulated by machinery. -- It fails to accurately show that the machinery is no more solid than the lego atoms that the machinery is manipulating. (Unless maybe the machinery material is made of some sort of selectively reactive/nonreactive, subatomic material)

When I see pictures & notions like that being bandied about and sold to the public, I get the same feeling when people push Jules Verne's voyage to the moon as science rather than science fiction. -- Baloney.

Right now Smalley wins. He's a doer, an implementer.

Drexler may get the last laugh in the far future, but some real science must appear first to make science fiction a reality.

The really hard stuff is in the implementation. The implementers deserver the real credit.

It will happen.

Plenty of people will say that molecular/atomic assemblers are impossible right up until the big breakthrough that makes it possible. That's how science works. People said that all sorts of computing stuff was impossible because vacuum tubes were too big, and then, all of a sudden, somebody figured out how to make transistors. All kinds of important stuff was impossible to figure out because the aether complicated it all and could not be measured, and then Einstein pointed out that it did not matter because the aether did not exist. Right now people are insisting that we will hit computing speed limits due to the limits of CMOS-but does anyone really think that there won't be a replacement?

Anything can happen with science. Magic is just what science cannot explain, because we have not figured out how to do it yet. But eventually, given enough time and resources, anything is possible.

Common misconceptions about our nanotech future

Most people do not really understand the potential impact of mature nanotechnologies. And it's easy to see why - even Drexler's book Unbounding the Future: The Nanotechnology Revolution gives some really ridiculous examples (may be to make it simplier to understand). Here are my responses to two of particularly misleading comments in this thread.

2BorgDrone [slashdot.org] :

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.
When molecular assemblers become mainstream, having a car would be rather pointless. First, there are unlikely to be any streets where you can impress chicks, since everyone would be able to live wherever on Earth they like. Second, there probably won?t be any roads, since you don?t need to transport goods (they can be manufactured from CO2 on the spot) and it?s easier to fly people from A to B. Third, designed cars would be as old-fashioned as horse carriages now ? smart completely transformable people-movers would be all the rage. And forth, you will be able to drive any kind of car in your personal virtual reality simulation, so you don?t need to actually design the car (just program how it should behave) and the issue of IP would be moot.

2jchoyt [slashdot.org] :
Money will still have value. Someone has to create and/or design food, clothing, medicine, entertainment, etc.
Strong AIs will be able to create and or/design everything, including these things you describe. Furthermore, people will not need food, because it will be easier to just get energy from the environment without any conscious actions like eating from your side. Clothing is likely to be designed for the sake of it. Most couturiers are not in this business for money, they do it because they like it, and when all fabrics and basic production operations will become free, as well as everything they need personally, they are unlikely to charge you anything for their latest fashionable clothes. Medicine will not be used, because our bodies will be redesigned to include a smart AI-based immune system, capable of fixing most problems, except, may be, for being in the epicenter of the thermonuclear explosion. So most things you mention will not be needed and those that still will be needed, will be done by professional volunteers for free.

Re:Tinkering with nature

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