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."

Comments

Kurzweil

[Ragelic]

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

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

Yum

[grub]

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

From the article:

[Steve 'Rim' Jobs]

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.

Re:Raises interesting questions

[Walterk]

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.

Well, I read the letters

[panurge]

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

[MarkusQ]

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

[iawia]

"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?

Scaring children - classic quote from Smalley

[fruey]

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.

If I had to bet

[MarkusQ]

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:Raises interesting questions

[BorgDrone]

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:I can see what the problem might be

[Zathrus]

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 ;) ).