Useful Functions from Simple Materials

John B posted some good technical questions in discussion following an earlier post.

However, let's assume that the only material that can be made into a programmable atomically-precise self-replicating assembler is diamondoid. .... How will you generate and conduct power with just diamondoid? OK, you could conduct via mechanical means, but how do you GENERATE power via pure diamondoid? Or are you going to limit yourself to non-selfreplicating power sources for your devices?

Well, if we can build diamondoid, then we probably have graphite and/or buckytubes, which gives us conductors, and buckytubes can be semiconductors as well. With a conductor and diamondoid, you can generate electrical power from heat (such as concentrated sunlight) via thermionics--CVD diamond thermionics have been demonstrated--and of course you can use the electricity in electrostatic motors.

Even if we have only mechanical devices, we can build macro-scale Stirling engines.

How will you fulfill an exponential need for feedstock with just diamondoid devices? Given a reasonably pure source of atomicly rigid materials, you might be able to pull off sorting rotors, but - how do you generate that reasonably pure source in the first place, and how do you scale that source up exponentially along with the need?

Bootstrapping won't need much material. Once we have a few sorting rotors built, we can use them to purify more feedstock. Microfluidics will probably be usable to generate the feedstock. If you don't have to pay extra for fabricating more features, then you can scale up a microfluidic design simply by making more of them.

Don't you have to make a functioning [nanofactory] first before you start commercializing it? And isn't the whole product rather more than just the self-replicating device in a closed system? Does it not include the controller for the devices (unless all you want is self-replicating devices, you'll have to control them somehow, not to mention error-checking and -correction routines), most likely some sort of clean chamber for atomic precision work, power supply, coolant (unless things go real slow), feedstock transport(s)?

A nanofactory could include simple computers, able to handle errors at a local level, so you'd just have to feed it the blueprint stream. (Mechanical computers work just fine at that scale.) And of course the nanofactory could also build the general-purpose computer with large memory to feed the blueprint to the factory. My nanofactory paper does include both computers and internal clean working chambers. Power, whether fed in electrically or mechanically, would not require much volume to distribute. Likewise for feedstock. My nanofactory design (which by the way is obsolete--there are much better architectures now) does not include the feedstock tank, refrigeration engine, or external heat exchanger, but those are all simple mechanical things that would not require much mass to build with diamond.

By now, some readers will have clicked away; some will be nodding in agreement; and some will be saying, "But that doesn't answer ______. There are so many issues to be solved!"

Yes, there are a lot of practical issues to be solved. To discuss all the issues would require a book; even to list them would require several pages. No one has pulled together this discussion, and anyone looking at only part of it will be able to find lots of [apparent] holes. But I have spent sixteen years thinking about this, and several years studying it intensively, and I think I have looked at most of the issues. Every one appears solvable. For most of them, the solution appears straightforward and does not impose much constraint on the rest of the system.

I am not saying that developing a nanofactory infrastructure will be easy. I'm saying that it could be done fairly quickly, given a well-funded well-focused effort--and that effort will be very worthwhile.

Chris

Comments

[John B]

I started out writing a detailed response with lots of questions, until I ran across the following text of Chris' - anyone looking at only part of it will be able to find lots of holes.

That in and of itself is pretty amazing, considering how bullish CRNano is on nanofactory design.

Chris continues in part, I have spent sixteen years thinking about this, and several years studying it intensively, and I think I have looked at most of the issues. Every one appears solvable.

I would urge you to write the book that looks at all the problems, Chris, and propose straightforward initial solutions. I would expect that such a work might well become as well known as the rationale behind the 640K limit on early PC's, and for similar reasons.

Note that this does not mean I consider such problems insoluable. Simply that 'simple' solutions often turn out to be a bit more difficult than initial impressions bring about.

Less negatively, it could provide a solid basis for future technical discussions, planning, etc. While this would not necessarily be painless, it probably would be a positive development along the road to nanofactory capabilities.

-John

[Chris Phoenix, CRN]

I started out writing a detailed response with lots of questions, until I ran across the following text of Chris' - anyone looking at only part of it will be able to find lots of holes.

That in and of itself is pretty amazing, considering how bullish CRNano is on nanofactory design.

Argh, apparently I didn't write clearly enough. What I meant was that if you look at only part of it, you will find lots of apparent holes. If you are able to look at the whole thing, you will see that the holes have already been thought of and filled.

I have had lots of conversations in which people started by asking about one issue, and when I gave a solution to that, they recognized that this solution had another issue--which I had a solution to... and so on.

It is rare that people will stick with this long enough to learn that every problem can be solved simultaneously. Perhaps this is because usually they aren't trying to understand the proposal, but to find something wrong with it, and they're just looking for an issue where they can say, "Well, we'll just have to agree to disagree, and so I won't believe it until it's demonstrated."

If all the issues and workable solutions for each were written down in one book, then the basis of conversation would shift from a repeated game of "I bet you can't solve this problem" (which has invariably been known and addressed years ago) to "I think this solution is flawed." That's a much more productive conversation to have.

I would compare the initial solutions, not to the 640K limit, but to the cassette port on the original PC. (For those younger than 40, the original IBM PC could produce and read audio tones to save files to an ordinary cassette tape recorder.) Solutions are not limits; you're free to replace them with better solutions.

Chris

[michael vassar]

I think that you were clear, and that the misunderstanding was snarkyness, not the result of genuine lack of clarity on your part.
Putting everything in one book does sound like a very sensible idea if you think that you are aware of the entire list of supposed problems and of solutions to each of them.

[Philip Moriarty]

... anyone looking at only part of it will be able to find lots of holes.

I think that John B's original interpretation is much nearer the mark than Chris' subsequent 'clarification' in the post above!

Chris states: "I have had lots of conversations in which people started by asking about one issue, and when I gave a solution to that, they recognized that this solution had another issue--which I had a solution to... and so on"

You suggested something similar to the statement above at the beginning of our debate . However, and as became manifestly clear during the debate, it's not solutions you provide - you merely put forward ideas . When challenged on the detailed physics and chemistry underlying those ideas (e.g. a FRET mechanism of force regulation, Freitas' 'shard' strategy for diamondoid mechanosynthesis, mechanosynthesis of graphene/graphite/nanotubes, error rates and error correction in mechanosynthesis, etc...) you invariably state either that 'more work is required' or 'well, if that doesn't work we'll try something else'. I agree that a given solution is certainly not a limit but please don't dress up an untested idea as a 'solution'.

Philip

[Philip Moriarty]

Chris also states: "Perhaps this is because usually they aren't trying to understand the proposal, but to find something wrong with it, and they're just looking for an issue where they can say, "Well, we'll just have to agree to disagree, and so I won't believe it until it's demonstrated.""

Yet again, you suggest that there is something inherently wrong with a critic looking for holes in a proposal. Moreover, if the proposal has not been demonstrated to work, then how can one call it a solution?! [Or perhaps this is some strange new usage of the term 'solution' of which I'm not aware...]

Philip

[michael vassar]

3 debate points to Philip for the Douglas Adams reference. Minus 3 for referring to an old use of "solution" as a new use of the word.
It's good to look for holes in proposals, but let's distinguish two types of holes. When I decide to go to work in the morning, I don't know whether the subway will be running or not, and I don't know whether the bus will be running or not, but I have a pretty high confidence that one of them will be, and if not I can walk. I don't consider lack of perfect detail to be a "hole" in a "proposal", though it is a hole in an excruciatingly detailed description. If I propose to fly an airplane to the moon, and you point out that there is a hole in the gasous medium which I was intending to push off of, that is a hole in the proposal. I can say "and if the plane doesn't work I'll try something else" but merely proposing the plane implies a lack of understanding of why it predictably won't work, and thus incompetence in planning. The "something else" in this case is also vague. Chris's plans are obviously somewhere in between those for the plane to the moon and those for the trip to work. It seems less useful to argue over which they are more like than it is to create another set of points between the two representing proposals made at different times for technologies that ultimately did or did not materialise, and set up an ordinal scale. An expert in the history of technology would be in the best position to do this, but one needn't look very hard to see that within a large range of project plausibilities the size of the holes does not very reliably predict the realization of the project. This is somewhat surprising, but suggests that extreme confidence by anyone is probably unwarranted. Proposals can be clearly possible based on physical calculations, yet take a long time to materialize, for instance, proposals heavier than air flight in the 1870s, or their fundamental possibility can be unclear yet they can be realized within a few years, as with Pennicillin or the atomic bomb.
Nanofactory proposals appear to me to stand on ground approximately as solid as heavier than air flight was on in the 1870s, and various proposals for "nanobots", in this analogy, may stand next to personal ornithopters or next to helicopters, it's rather early to tell. Many more speculative proposals (practically any of the big ones from the early 20th century, practical automobiles for instance, or electric light) have materialized rapidly. Many histrical proposals have stood on firmer ground and we're still waiting (flying cars, fully automated factories, affordable space travel).

[Karl Gallagher]

Oh, flying cars we've got, lots of 'em. Google the term. Nobody buys them, they buy a car and a plane instead. Compromise designs can't match the performance of optimized ones.

[Philip Moriarty]

Michael,

(First, glad you spotted the Douglas Adams reference! I don’t know if you’re aware that BBC Radio 4 have brought/ are bringing the final three books of the H2G2 ‘trilogy’ to radio (with most of the original cast).)

Re. your comments:

I must admit that I don’t ‘get’ your statement re. the ‘old use’ of the noun ‘solution’. Any of the dictionaries I’ve consulted give definitions of the term very similar to those below (from hyperdictionary.com).

'solution

-[n] the successful action of solving a problem; "the solution took three hours"
- [n] a method for solving a problem; "the easy solution is to look it up in the handbook"
- [n] a statement that solves a problem or explains how to solve the problem; "they were trying to find a peaceful solution"; "the answers were in the back of the book"; "he computed the result to four decimal places"
- [n] the set of values that give a true statement when substituted into an equation

I therefore stick by my original comments. That is, solutions have not been provided. Rather, what has been presented is a series of untested ideas/ speculations which in many cases, when scrutinised, are either flawed or lacking in sufficient detail. [Chris, if you feel that baldly stating this is tantamount to ‘snide rudeness’ then I apologise, but my comments would not be out of place in, for example, a referee’s report for a peer-reviewed journal. There are perhaps good reasons why peer review is generally an anonymous process…]

As to your comments on ‘holes’ in proposals, I’ll quote from a comment (by Eric Kidd) on “Soft Machines”:

"Drexler’s work in Nanosystems rests on the assumption that feasible mechanosynthesis operations exist for stiff hydrocarbons. If such pathways can’t be found, Nanosystems collapses like a house of cards"

The onus is on CRN and the proponents of Drexler’s MM ‘vision’ to find an appropriate scheme to implement the lowest level mechanosynthesis steps. One simply cannot state that “the holes have already been thought of and filled” when a gaping hole exists in that a workable scheme to implement the machine language of MM does not exist.

I wholly agree with your statement that “extreme confidence by anyone is probably unwarranted” (but that of course applies to both sides of the debate). Am I entirely ruling out the possibility that for a very limited set of materials a technology similar to MM might be developed? No, I can’t do that. Do I share your confidence re. the development of nanofactories? No, but, importantly – and in answer to a comment you made elsewhere - I have no basis for quantifying my scepticism. You’ve stated elsewhere that it is “entirely legitimate to make up probabilities” and that “we all start our enquiry by making up probabilities”. I must admit that I certainly don’t tend to make up probabilities and can’t agree that it’s ‘entirely legitimate’ to do so – why attempt to quantify the unquantifiable?

My ‘take home’ message on this is that it is misleading at best (and disingenuous at worst) for CRN to state “if you are able to look at the whole thing you will see that the holes have already been thought of and filled”. As the “whole thing” must, by definition (!), include the lowest level mechanosynthesis steps, this statement is patently incorrect. (See this link for more debate). Moreover, to state that all holes have been filled when there are huge misconceptions re. the underlying physics beggars belief. (See, for example, Richard Jones' recent explanation to Chris of the difference between free energy and potential energy. Somewhat similar arguments re. the entropic contribution to the Gibbs free energy at any finite temperature have been put to Chris in the past and apparently ignored. In particular, this distinction is not only covered in undergraduate physics and chemistry textbooks but is covered in some detail in a number of surface science books previously cited to Chris.) Time and time again, similar misconceptions crop up. Visit Soft Machines for more examples.

On a different point, there have been some extremely interesting comments posted on the CRN blog recently. In particular, Jim Moore's comment on the meaning of temperature at the nanoscale is insightful and is related to a lot of complex physics which is only now beginning to be studied in any type of detail (for example, in August of last year a paper was published in Physical Review Letters - the premier physics journal - with the title "Existence of Temperature on the Nanoscale" [PRL 93 080402-1 (2004)]. Chris' response to Jim doesn't even begin to scratch the surface of the complexity of equilibrium and non-equilibrium thermodynamics at the nanometre level. As noted above, Richard has already pointed out a number of key holes in Chris' arguments. As I have a keen interest in non-equilibrium thermodynamics at the nanometre level, I'll contribute to the discussion of 'nanoscale temperature' later this evening.

(I stated some time ago that I planned to leave the debate re.MM. However, hyperbole such as Chris' recent comments re. 'all holes being filled' and, more positively, excellent thought-provoking questions such as that posed by Jim Moore tend to keep dragging me back...!)

Best wishes,

Philip

[“I’ve done the math enough to know the dangers of our second guessing……”, MJ Keenan, ‘Schism’, © Toolshed music (2002)]