Responsible Nanotechnology

Chris Interviewed On Gray Goo

The SETI Institute has a radio program called "Are We Alone?" and this week's broadcast covers slimy things - from slime mold, to gray goo.

Click on "You've Been Slimed" on their home page to hear the interview [mp3]. My segment starts 28:00 in and runs to 36:08.

In the introduction, before they start interviewing me, they assert that gray goo is a risk of molecular manufacturing, since molecular manufacturing will, they assert, require self-replicating robots. I wish they hadn't done that, but I suppose they wanted to make gray goo sound scary enough to be worth talking about.

I think I did a pretty good job of explaining that molecular manufacturing will involve large (human-scale) factories full of inert tools - no self-replicating robots at all. I gave a bit of history of the gray goo concept: why it was originally a concern of Drexler's, and how and why his thinking changed about the way molecular manufacturing would be implemented.

I expect I'll be doing a lot more public speaking in the future. Any advice on how to present myself or my ideas will be much appreciated.

Chris Phoenix

Josh Hall as Foresight Institute President

The Foresight Institute held an event in Palo Alto earlier today, at which Josh Hall spoke in his new capacity as president of Foresight. He has been involved in molecular manufacturing for two decades; his accomplishments include founding the sci.nanotech newsgroup.

I expect Josh to bring a more technical and future-oriented focus back to Foresight, which for the past several years has (from my point of view) mainly been active in promoting stories about how good near-term nanoscale technologies can be. Nanoscale technologies are incremental steps away from familar technologies, and raise familiar issues; they are far less perilous than molecular manufacturing, which is why CRN has largely left them to other organizations.

It sounds like Foresight will be focusing on artificial intelligence as well as molecular manufacturing; Josh is an accomplished AI researcher. (And AI was a focus of Foresight back when it was founded; although it focused on molecular manufacturing, its mission was to address a variety of advanced technologies.) CRN won't have much to say about AI.

But I'll be watching closely to see how Foresight handles molecular manufacturing. Will Josh be able to redirect Foresight away from its current focus on "Advancing Beneficial Nanotechnology" to address the negative implications as well? I asked him today about Foresight's earlier slogan, "Good for people, good for the planet," and he did not like it. So maybe Foresight will be moving toward a more balanced view of the perils as well as the promise of molecular manufacturing. If they don't, CRN will just have to do our best to balance the picture.

Chris Phoenix

Fun With Atoms

Atomic force microscopes (AFM) have been used for quite a while to push atoms and molecules around on a surface. But it's still interesting when a new way is found to not just move atoms, but replace one atom with another of a different type.

Hat tip to Eric Drexler's Metamodern blog for this story: a new way has been found to make patterns of atoms in a crystalline structure. A monolayer of tin on silicon can have individual atoms replaced with silicon. It seems that some AFM tips, when pressed hard into the tin layer, will swap atoms between the tip and the surface. Since the tips are silicon, the tin on the surface can be replaced with silicon.

Some tips always replace tin with silicon; some swap back and forth; some apparently always replace silicon with tin (though I'm not clear on where the tin comes from). In any case, there's a fairly wide variety of behavior.

Another interesting aspect of this work is that it is done at room temperature. I may be beating a dead horse here, but it will take a while before I say it as many times as skeptics have said the opposite: Yes, atoms can stay where you put them, even at room temperature. Conversely, the tips do rearrange themselves, taking some time to "recharge" and expose another atom to be transferred.

Eric's blog (linked above) has a time-lapse picture of the process.

Chris Phoenix

Efficient Robots, Part II

I started to respond to a comment on my post about efficient robots, then realized that I was writing a blog entry.

The commenter said that I was simply defining robots differently than Drexler. I disagree. I tried to define robot carefully so that there'd be a gray area of continuity between a really simple robot and a fully flexible general purpose robot. By doing this, and showing that a simple robot can be controlled without computation during manufacture, I can also show that (in theory) a complicated robot can be controlled efficiently. This changes the terms of discussion from whether or not robots can be efficient, to what kinds of robot are most most useful in an elegant nanofactory design.

The machines Drexler showed in his videos, I would not consider robots. They perform only one trajectory to make only one type of product. I'm sure there will be some of these in a practical nanofactory.

On the other hand, a machine that could do any of a dozen fabrication operations (plus, if programmed wrong, a thousand other operations that don't do anything useful), would, I think, be a robot by both Drexler's and my definition. If computation had to be done for each fabrication operation, in order to control that robot, then that robot couldn't be used to do molecular operations on kilogram scales.

My point in these posts is that robots - even very complex ones, the kind that Drexler surely would consider robots - can be sent pre-compiled recipes without computational cost during the manufacturing operation, and thus can (in theory) be efficient enough to do molecular operations.

The trick, by the way, is to build efficient copying and counting operations into the control hardware - the robot controller would be a lot more like a DMA controller than like a CPU.

Chris

Chris Phoenix

Don't Forget CRN's Thirty Studies

A couple of days ago, Todd Andersen suggested that we create a list of tech questions related to developing molecular manufacturing.

We already have a list of questions. The first sixteen of our Thirty Studies - especially #3 through #12 - relate to the development of molecular manufacturing capabilities by various pathways. The studies were published several years ago, but are still quite relevant.

New technical questions keep arriving - Todd contributed four, and others come in through our web feedback form - and I plan to answer them on this blog.

Chris Phoenix

Background Radiation Vs. Nanomachines

Todd Anderson asked a good question in our blog comments:
"Will shielding be needed for background radiation in the device and is there any know element that can protect the inner workings of the MM device? Or will another kind of shielding be needed i.e. magnetic or a new as yet unknown one?"

I don't know of any way to shield against all background radiation. Even alpha particles, which can be stopped by "a piece of paper" - a piece of paper is small compared to a tabletop device, but large compared to, say, a medical nanodevice. And there are other kinds of radiation that are more penetrating.

So there will definitely be some level of radiation damage. (By the way, this level of damage is many orders of magnitude larger than errors from entropy, Heisenberg uncertainty, or any of the other weird physics that skeptics like to invoke to make molecular manufacturing sound difficult.)

To deal with damage, use redundancy. If you need eight parts to work, include nine in the machine you're designing. Do that at several levels, and a machine with quadrillions of sensitive components can reliably keep working for years with something like 30-40% extra machines.

Biology, of course, uses self-repair, metabolism, and other kinds of error adaption. But they're not necessary in engineered nanomachines.

Chris Phoenix

Modeling the future

Tom Craver has an interesting idea: a Wiki model of the future.

Such models have equations and parameters, and (for example) simulate what will happen to the economy in a year or two. The Club of Rome built such a model, and their model has been very influential.

So, is it possible to build an open-source model? One in which anyone can contribute a bit of insight or knowledge, and the system processes all the bits until it comes out with a useful set of projections about the future?

CRN has engaged in online collaborative projects before, including our groundbreaking scenario project. And a model of the future would certainly be useful to us.

Of course, it wouldn't be just one model. A useful system would run lots of projections using different variants of the model, and then aggregate the projections, looking for patterns in the relation between assumptions and outcomes. This would take a lot of computer power, and could be done on an @home type platform.

The information input into the scenario process would benefit from semi-automated Delphi-like feedback. Different versions of a piece of data would be rated according to how they matched opinions from other users, as well as what effect they had on the model.

Does anyone here know enough about mathematical modeling of the future to say whether this idea might be worth implementing?

Chris Phoenix

Destructive Nano Video

Well, that's a nice welcome-back-to-work for you.

Two days into my new/old job, and I hear from Mike that there's a nano video going viral. It's hosted, no surprise, by none other than Wired, which also published Bill Joy's anti-nano article in 2000. Nanotechnologists take note: Wired wants to destroy your funding.

I wish I thought that videos like this would raise public awareness of the implications of molecular manufacturing. But I don't. This video is not just about destructive nano - it is a destructive video about nano.

So what's wrong with the video? Like all good lies, it contains grains of truth. Here are a few of the half-truths:

• "Because it takes so many of these microscopic machines to do large-scale work, self-replicating nanobots will be pretty common in laboratories."

It is true that it takes many small machines to do large-scale work. The lie is that these machines will be free-floating and self-replicating, rather than being fastened in place like the conveyor belts and drill presses in a factory.

• "Rather than replicating using the rarest materials, program the nanobot to use the commonest."

It is true that molecular manufacturing will provide lots of design flexibility. The lie is that machines can simply be programmed to change their fundamental construction: it's like saying "program the tree to grow on gasoline." More accurate would be "Design a whole new nanobot from scratch, because nothing like it will exist."

• The overall message of the movie is that molecular manufacturing is powerful enough to be extremely scary.

It is true that molecular manufacturing will be immensely powerful and easy to misuse. The lie is that grey goo is the biggest danger. Deliberate institutional misuse of the products will generate more perilous and more urgent threats, which will be more difficult to prepare for.

At least I can hope that, nine years after Bill Joy's article scared nano researchers into claiming that molecular manufacturing was impossible, the researchers will react a little more calmly and reasonably this time. CRN has been explaining the realities of grey goo for years, and I co-authored a paper, "Safe Exponential Manufacturing," with Eric Drexler in 2004 on the topic.

While this video may scare the uninformed, perhaps the actual discussion of molecular manufacturing will emerge stronger and more sensible than before. I welcome your suggestions and actions toward this goal.

(Edit: I originally said Joy's article was in 2001)

Chris Phoenix

Yes, I'm Back From Sabbatical

As of Monday, Mike Treder moved to IEET, and I'm back in the saddle at CRN. I plan to do several tech posts per week, interspersed with more newsy or talksy posts (of which this is one).

Future plans for CRN include a new look and feel for the website. And I'm working to set up something approximating online tech-focused panel discussions with other notables of molecular manufacturing. And the newsletter will start coming out regularly again, with science essays.

You readers who have stuck with CRN this long - it is, in a very real sense, your organization. I want to thank you for your continued attention. And if there are things you want to see in CRN, now's a very good time to suggest them.

Chris Phoenix

The Much-Maligned Second Law

I just read an article that R. Stanley Williams wrote a few months ago, about his team's development of the "memristor" - a nanoscale crossbar switch that changes its resistance depending on how much current has flowed through it.

At one point, Williams describes the difficulties of building a nanoscale circuit: "Like everything else at the nanoscale, the switches and wires of a crossbar are bound to be plagued by at least some non-functional components. These components will be only a few atoms wide, and the second law of thermodynamics ensures that we will not be able to completely specify the position of every atom." (Dec. 2008 IEEE Spectrum, p. 33 column 1.)

I went and looked up the second law, just to make sure... and it says no such thing.

One formulation of the second law is: "In a system, a process that occurs will tend to increase the total entropy of the universe." So, if the circuit is considered as an isolated system - for example, once it has been constructed and sealed in an integrated circuit package - then if an atom in a circuit were to move, it would be more likely to move out of place than into place.

During fabrication, of course, the circuit is not an isolated system. The second law doesn't prohibit spending energy in the fabrication machinery in order to move atoms into precisely the desired place. That sort of thing happens all the time, in nature as well as in technology.

There is an obscure corner of the laws of entropy that says that in a sufficiently massive crystal, a certain percentage of the atoms must be out of place: a sufficiently large crystal at room temperature can't be perfect. I calculated once how large the crystal must be before the laws of entropy required it to contain a single atom out of place. I forget, now, whether it was thousands or maybe billions of tons - the point is that there's nothing in physics which requires atoms to be misplaced on the scale of integrated circuits at room temperature.

To blame the second law of thermodynamics (or any of the other physical laws) for the errors that creep into modern-day semiconductor fabrication is simply incorrect. Semiconductor fab errors are due to limitations in technology, not physics.

To blame physics for atoms out of place spreads the misconception that atomically precise devices can't be built. That is as fundamentally incorrect as the old ideas that airplanes couldn't fly faster than sound, or railroad engines couldn't go faster than fifteen miles per hour. All these ideas are equally baseless, but were used at the time as excuses for limiting engineering efforts - and projections of technological capability. It's a shame to see even an accomplished nanotechnologist spreading such ideas.

Chris Phoenix