Saturday, August 19, 2006

I'm a Nanotechnology Skeptic

I’m a nanotechnology skeptic. It seems like nanotechnology, as I understand it, and nanotechnology, as the popular futurist conception of it is, are two different things. You might be wondering at this point “What kind of futurist are you anyways? Nanotechnology rules. It can do anything”, which is sort of my point.

People seem to think nanotechnology can do anything. In fact, it seems they want it to be able to do anything. It seems to me almost as if people are reasoning backwards, from a desired outcome to a predetermined thing-that-should-make-it-possible. Nanotechnology is treated as a magical substance, instantly and effortlessly manipulating the world to exactly our specifications. Causing whatever we desire to appear on a whim. Turning material considerations into mere abstractions that won’t require any human attention, ushering in a classless society, and abolishing war (that should be your first clue that the desired outcome is searching for a cause, rather than vice versa) It’s also supposed to be unstoppable grey goo that could eat our entire planet with microscopic self-replicating constructors.

But when you look at things from the perspectives of the challenges facing us in even developing microscopic mechanisms, a lot of these scenarios don’t make sense.

The easiest one to debunk is the runaway replicator “grey-goo” scenario. Seeing as how we haven’t even built macroscopic von Neumann constructors (devices which are capable of producing themselves under automated control) (though by no means is this unreasonable, for a macroscopic device) that microscopic von Neumann constructors are just around the corner.

First of all, lets define how these replicators are supposed to assemble:
1) What materials are they going to assemble from? If they are going to assemble from pre-made parts, then it’s impossible for them to run wild in an environment that isn’t saturated in these pre-made parts. If, on the other hand, they are constructed from raw materials, the replicators would have to contain microscopic factories to fabricate these parts from raw materials. (Which drastically increases size and complexity – you do want these things to be microscopic, right?).

((An important caveat – I’ll get to this more at the end of the article – Life is composed of “nanotechnology” of sorts. Life has managed to solve nearly all the problems of operating at microscopic degrees of scale. It also comes with its own limitations and considerable advantages. But that’s not the popular conception of nanotechnology. The popular conception of nanotechnology is, essentially, precisely designed machines after the manner of our macroscopic devices, operating in a similar manner, using similar methods . . . just tinier. My main objections deal with this conception of nanotechnology))

a) These factories need some sort of control mechanism. If this control mechanism is an electronic computer, then these “nano-devices” aren’t going to end up being very nano in scale. Electronic computers are necessarily macroscopic devices. You need a certain minimum size for transistors to work (around 50nm/transistor), for heat to adequately dissipate, for electromagnetic interference of one switch to be minimized at the next one over, ect.
b) There are, of course, other types of control mechanisms, but these are severely limited with respect to the directness of our control. One such example is the chemical “computer” of our DNA. If our nanotechnology devices are controlled by such means, then it means that we won’t be able to give each device real-time marching orders. The best we could do is give behavioral pattern type instructions and turn them loose to do their thing.
c) Are these devices going to assemble from metals? If so, your replicators can’t run wild, seeing as how they would need a metal rich environment in which to draw their materials from.
----i) How are you going to get the energy to work metals anyhow?
d) The only real option for runaway replicators is for them to be assembled from ubiquitous materials such as carbon, hydrogen, oxygen, nitrogen. The same materials that life in general assembles from. But this brings up a host of issues, not the least of which is that you’re not making tiny little machine tools and lathes out of sugars, amino acids, and other molecules that would rather dissolve in water!

2) Where will these runaway replicators get the energy to run-away? It follows that for this grey goo to be able to eat the world, it has to have an independent energy source. If it gets its food from operating in a fuel medium, then it can’t run away.
a) If they get their food from eating other organisms and burning their molecules, then the replicators have to be able to get a sufficient energy return on their investment. That means that they not only have to be more efficient than life at doing what they do, they also can only attack and survive in organisms with a sufficient density of consumable molecules. They can’t expand and eat just anything. They would be, at worst, opportunistic parasites.
b) If they use solar power to replicate, then they can get independent power. But the power available to your grey-goo is not going to be sufficient for it to chase people around the block and eat city blocks within half an hour. In fact, it would be downright slow – no faster than your average moss growing on a pond, assuming they are even as efficient in self-replication.

3) This just segues into the next point: Will these devices be able to out-compete life? Will it be the nano-devices that end up snacking on people, pavement, plants and other life, or will bacteria and viruses be the ones eating your nano-devices for lunch? They are made from similar materials, but life has a serious advantage over designed nanotechnology: It is supremely adapted for operating on its degree of scale. Billions of years of ruthless competition have resolved the microscopic world of life into self-replicating surviving, eating, breathing, metabolizing, photosynthesizing machines of extreme complexity, unsaddled by human preconceived notions of what replicators should operate like. Would we be capable of designing anything to beat that so easily? I think not.

So now on to mechanical nanotechnology in general: By now, if you’ve given it some thought, you can probably see how little tiny robotic arms are going to be a bit problematic on the nanotechnological degree of scale. For one thing, it’s hard to get anything to be rigid if it’s only a few thousand atoms across. Temperature introduces noise at that degree of scale. Furthermore, chemical electromagnetic forces come into play that make operating a little tricky. If your robotic arm grabs a large macromolecule, the molecule might not decide to come off! It might electrostatically bind to the end of the arm. If it chemically reacts with your arm, it’s likely to release so much energy (for the degree-of-scale that we’re talking about here) that it fries your device, as well as putting extreme loads on the arm. Grabbing molecules with “little tiny robotic arms TM, would be like handling glue-coated land-mines with blunt jello baseball bats. Corrosion would be deadly to a nanodevice. A reaction with a stray oxygen molecule in the wrong place could eat through a critical mechanism (and fry the device through energy release). (The best defense against grey-goo is likely to be a lysol wipe. )

So, as you can see, producing mechanical nano-devices is simple. It’s just a matter of making a really really tiny self-replicating robot, and you’ll be ordering mountains of matter around on the molecular level (effortlessly, btw), and blackmailing the world with planet eating grey-goo in no time. /sarcasm.

Mechanical nanotechnology could probably be made to do some important work, such as ordering molecules around on a microchip, constructing microscopic sensors, threading the wiring for other very small devices. What it is not likely to be is effortless or cheap, since it is not likely to have the capability to easily self replicate. You might be able to get your nano-metallic-print head for a layered-substrate type of device, but it will probably set you back some, since it is likely to be a very tricky thing to construct.

Biological nanotechnology:

I’m not a complete curmudgeon when it comes to nanotechnology replicators however. I do think that there is one type of nanotechnology replicator that might work some real wonders if we keep at it. Rather than re-inventing the automobile starting in the stone age, let’s hijack some of the wild ones running around in the open plains, so to speak. You’ll probably get more mileage by ordering bacteria around, giving bacteria the genetic instructions on what you want them to do, rather than attempting to build the things from scratch with tweezers and a microscope.

This offers some advantages – the nanotechnology, once told what to do, will be able to self-organize into structures of extraordinary complexity.

One advanced example might be neural interface. You could try doing neural interface the old fashioned way by going in with tweezers, and attaching metal electrodes, but this is a rather blunt way to do things. For one things, your neurosurgeon would have to have very steady hands and an extreme amount of patience (1 retinal connection down, 100 billion to go ….) These connections are also likely to produce allergic reactions, or kill the nerve cells they’re next to. If you could produce the connection by having micro-organisms go in under the orders to interface with the neurons and create neuron chains back up to the surface, then expand their resolution out to something that a mechanical device can handle, you could create the biological equivalent of an interface port. Furthermore, inside your skull, these microorganisms could be equipped with all your surface markers, so that your immune system doesn’t reject the interface. I really don’t see too many other ways to get the sort of intimate mind-machine interface depicted in the Matrix than to do it under the fine and autonomous control of biology.

Another example might be the improvement of your immune system. If you can create some mean-lean-fighting bacteria with an improved understanding of what constitutes an invader to your body, then you could give them the body’s cell markers and send them in to kick butt throughout your numerous lymph-passageways.

You could grow multi-cellular “meat” in a vat of oxidized sugar-water (after making sure you seal off the tank from other less tasty opportunists, like mold and rot). You could probably create new culinary experiences of extremely interesting variety and texture by controlling how your organism goes together. You could use a multi-cellular organism to produce any sort of conceivable organic molecule assuming you can tell a ribosome or a protien how to turn it out.

However, the disadvantages of biological nanotechnology are also the disadvantages of life. Some of the difficulties that I forsee in using them to construct macroscopic devices are given below:

1) It’s not going to be instantaneous. In fact, it’s not even going to be all that fast. If you plant your crop of car bodies in May, they might be melon sized by June. If it’s in a vat of fuel, it may grow faster, but it’s not going to be as fast as a big blunt stamp on sheet metal.

2) How do you say 14.5 inches +/- 0.001 across in a self-organizing pattern language, like you would with DNA instructions on how to organize and grow? Life forms up and grows according to patterns. It usually assembles and iterates out the pattern, then begins growing according to the pattern to the best of it’s ability.

If you, say, planted a crop of bio-nano-replicators that are supposed to assemble the copper sludge in the bottom of a nutrient tank into regenerative rocket nozzles, then your rocket nozzles are likely to come in as varied an amount of shapes and sizes as the tomatoes in your back garden. Some might be four feet wide. Some might be three feet wide. Some might have larger nozzles in relation to your combustion chamber. Some combustion chambers may not be exactly cylindrical. The throat area would vary as well. Some might be stunted. Mechanically, it would be a disaster.

Lastly, it’s not going to be effortless or free. It’s not going to provide people with free products and services, or pave the way for an economy where you can be a bum and reap the sorts of rewards inherent in this technology. This is because it is going to take a whole lot of sweat and effort to make these nanotechnology devices do what they’re supposed to. You’ll have to have macromolecule designers that figure out what you want these things to go into your body and do. You’re going to have biological programmers that figure out how to encode what you want the bacteria to do in the madcap language of DNA and RNA. You’re going to have trial runs to see if these replicators do only what you intend them to do (rather than having your mind machine interface organism setting up shop in your kidneys and growing tumors as well, or your macromolecule factory bacteria producing not just some miracle drug, but also a nasty allergen while it’s at it). You’re going to have nano-device farmers that take the finished product out of the tanks and cut off all the assembly sludge, waste products, and unneeded tissue. All these people will want to be paid. They’re not going to be impressed with this classless economy nonsense.

I envision nanotechnology being primarily used for fine control. For going in and producing biological effects of extreme complexity. For producing small devices of similarly extraordinary complexity. For farming out macromolecules, or growing food tissue, or being used as a biological recycling mechanism for life support.

But I don’t envision it as being used to grow cars and construction equipment. If you need to bend metal, you’re probably better off having a macroscopic robot pick up a macroscopic hammer (or die) and go at it the old fashioned way.

Well, that's my long winded opinion. What do you think? Discuss. Discuss, I say!!

5 Comments:

Anonymous CosmicConservative said...

qwerty:

Wow, that's a lot to respond to.

I'm a skeptic by nature and you do bring up some very good points. I particularly like your thermodynamic analysis where you make the point that for nanobots to overcome life to create a "grey goo" they would have to be more efficient than life at harnessing energy. That's not a bad systemic way to view the issue, although I don't think it clearly provides any proof that nanobots WON'T be more efficient than life.

Yes, when you get right down to it, life is essentially nanotechnology. The difference is that the nanotechnology of life is more or less cobbled together by billions of years of evolution, there's a lot of overhead associated with dead ends that still hang around, mutations that are not enough to harm an organism, but reduce its effectiveness (which is OK for life because all organisms have some level of inefficiency "built in" throuh legacy mutations so that none gets a huge natural selection advantage).

If we speculate that designed, directed nanotechnology could actually cull out these inefficiencies, then perhaps the gray goo is not so impossible after all.

My own perspective on nanotechnology is that it is likely to revolutionize everything from materials construction to medicine. I'm not a nanotechnology booster, I just think that very small advances in the field can have huge payoff in the real world. So even if the "futurists" who see us constructing spaceships one molecule at a time are dreaming, the possibility of having nanobots that clean cholesterol out of our bloodstreams is worth pursuing all by itself.

It isn't nanotechnology on its own that will change the world, it's in combination with digital processing advancements (computers) and biomedical advancements that the major changes will come.

Nanotechnology may have a practical limit, but I don't think we're close to it yet, and I don't think it's clear where that limit is.

One more point. There is no reason that nanofactories could not be made to provide nanobots with refined components to use, and the nanofactories could potentially be self-replicating too.

The proof of this is in every living cell on earth today.

Sunday, August 20, 2006 10:00:00 AM  
Anonymous Gordon said...

Thanks for your comment on AeroGo. I wrote in reply to you there about my general view of nanotechnology and its value to aerospace.

Regarding your comments here about replication, to me replication is just a very small part of nanotechnology. Of course, if it works, it will be very important.

Self-replication as a concept reminds me a lot of the Jurassic Park concept. When I first read a short story about it (c. 1981), I was intrigued but figured it would take a couple of centuries before such a breakthrough might be feasible.

Of course, sequenators, PCR and other huge advances in the early 80s brought us quickly to a point where it seemed possible, even probable, that we'd see such breakthroughs in our own lifetimes.

In 1980, self-replicating machines also seemed at the very far edge of what might be possible in the distant future, i.e. centuries away. Now, advances in computers, rapid prototyping and nanotechnology are prompting serious research efforts, some of which reportedly hope to produce prototypes very soon. As I understand it, many of these don't rely on nanotech.

Now, there was at least a third such extreme edge technology (I don't consider solar power satellites, for example, extreme). That was terraforming, which as far as I know, is still extreme edge. But you never know ...

Actually, now that I think about it, the space elevator was also almost as extreme, and nanotech may well solve that problem, though they've got a ways to go yet.

I think the real hidden problem with nanotech is not whether you can get it to work, but its potential environmental effects. Early studies have found considerable toxicity even in fairly mundane materials such as fullerenes. Here in Houston, Rice is doing a lot of work in nano, including preliminary research into biological & environmental effects.

Monday, August 21, 2006 9:34:00 PM  
Blogger qwerty182764 said...

Thanks for the reply Cosmic Conservative, and Gordon.

"The difference is that the nanotechnology of life is more or less cobbled together by billions of years of evolution, there's a lot of overhead associated with dead ends that still hang around, mutations that are not enough to harm an organism, but reduce its effectiveness (which is OK for life because all organisms have some level of inefficiency "built in" throuh legacy mutations so that none gets a huge natural selection advantage)."

I suppose it's a matter of just how fit life, or designed machinery are in comparison to each other. I doubt, seeing as how there is such a huge population of microorganisms competing over such a long period of time, that there would be any "uniform incompetence" in doing what they do.

Perhaps it is possible to operate in a manner entirely different than that of life on that degree of scale, in which case we may be able to beat life in certain aspects. But if we're using biological devices to do our work (RNA/DNA/Proteins), I wonder if it's possible to do it better than is already done (if life has already found all the efficient "fitness points" in "design space"). Considering the madcap paths that evolution would take such life through to get to these points, I wonder if we can get as close ourselves without the aid of genetic algorithms and computer design searches.

Anyway, some contrary speculation on my part. I realize that life can do quite a lot, and under our control, the same processes will be able to accomplish a great deal. My primary quarrel was with the pop-culture image that has nanotechnology tearing things apart, doing the Terminator, and the futurists who bank on it effortlessly eliminating all material concerns.

Gordon: Nah - terraforming is way more extreme than space-elevators are. A space elevator is just an extremely long cable made out of material with properties we can't do yet. It's a tensile strength issue - if you can get it, then you can build a space elevator. If not, then you can't.

Terraforming is rearranging the surface, atmosphere, and chemical composition of an entire planet - a project that mocks our accomplishments so far in the sheer magnitude of energy and material requirements. We're talking about Terratons of material imported to a planet and Giga-modern-mankind-centuries of energy and effort being applied.

Wednesday, August 23, 2006 5:19:00 PM  
Blogger Robert Reed III said...

Nice writeup. I haven't read many dissenting viewpoints of nanotechnology.

My take is that we are perhaps making decisions a little too early. We've already made self-replicating robots at the scale visible to the human eye. And this technology is at the very beginning. But I would like to see such a machine at the micro level before people say that it is possible at the nano level.

Saturday, August 26, 2006 6:11:00 PM  
Anonymous Anonymous said...

Hi Qwerty,
Any chance it would be okay to reprint your article "I'm a Nanotechnology Skeptic?" It would be going into an anthology of sorts that's used at high school college level to teach about "opposing viewpoints." Each book is centerd on a topic and presents opposing viewpoints about the topic. The title of the book that this piece would go in is, not surprizingly, "Nanotechnology." Your piece would agure that molecular manufacturers are not feasible (or practical or possible...), while a piece by Eric Drexler argues that they are.
If you decide its okay, unfortunately the publisher (Gale Cengage Publishing Group http://www.gale.cengage.com/) needs your real nam, i.e. I can't attribute your article to qwerty.
Please reply to jaxcie@charter.net or jklisz@cengage.com
Thanks!!

Tuesday, December 09, 2008 10:22:00 AM  

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