Drexlerian nanotech

[Drashner1]

Let me clarify, then. By "drexlerian nanotech" I mean not things derived from Drexler's ideas, but those ideas themselves. Which, as I understand it, is exactly the individual nanoscale robots operating independently that you mentioned, often in an uncontrolled environment. However, my knowledge of his work comes entirely from Engines of Creation, so I suspect that my idea of it is quite incomplete. Anyway, you must understand that I wholeheartedly agree with the idea of an OA nanofab, and I am simply pointing out that Drexler's original work, and by extension most depictions of nanotech, do not incorporate these ideas.

Actually, this isn't correct (or may be seen as a matter of interpretation). I have Engines of Creation and Drexler's other books in hardcopy and while it's been a while since I last read them, as I recall, Drexler addresses this as follows:

E of C:

a) An example of a single replicator floating in a vat of chemicals - he states that, within a matter of days, the replicator and its progeny could consume a mass equal to the sun and all the planets - if the vat of chemicals didn't run dry long before.

b) A description of the creation of a rocket engine via nanotech in which a 'seed' (mainly used for command and control) is lowered into a vat which is then filled with a mix of feedstock and nanobots. The bots proceed to link up first to the seed and then to each other under the seed's command to form a sort of 3D mold or armature (similar to OA descriptions of engenerator tech) which then proceeds to grab feedstock elements out of the mix and assemble them together into the overall rocket engines. Other elements of the armature act to move feedstock through the structure and to pump liquid through for cooling, etc. Different nanobots lay down feedstock matter in different types and ways to form diamondoid, sapphiroid, etc. depending on the structural and temperature needs of the engine and all based on the design coded into the seed. After less than a day, the engine is complete, the nano and feedstock mix is pumped out, the engine is hosed off, and removed from the vat to be sent where it is to be used. Drexler also mentions that in principle you could just make an entire space shuttle this way.

c) A single line in the section on possible dangers of nanotech in which Drexler states that a nanotech based 'plant' that operated more efficiently than natural plants could outcompete them and essentially consume the biosphere.

Unbounding the Future:

a) Drexler spends more time talking about possible dangers of nanotech, during which he explains that he no longer feels that 'grey goo' is a serious threat, basically because the odds of a replicator accidentally escaping in 'the wild' and being able to survive and flourish there are about the same as an automobile somehow getting loose in the woods and figuring out how to survive off of tree sap rather than gasoline. While he doesn't say that grey goo replicators or nanobots operating outside of a controlled environment are impossible, he does make it clear that such devices would both represent a much higher level of technology than what he is considering and that they would almost certainly have to be deliberately and carefully designed to operate 'in the wild'.

b) Drexler devotes quite a bit of space to 'Desert Rose Industries' a mom and pop factory complex that manufactures a huge range of goods. There is a scene in which a big batch of tents are made to send to the site of a disaster. The factor is described as containing big vats into which feedstock (some of it pre-fabbed at other dedicated facilities using specialized equipment to make components -some of it just raw materials for construction or chemical energy) if fed and then converted into finished products by various forms of nanobots.

c) Drexler spends a portion of the book talking about various more 'factory floor' type nanodevices, including mills and motors and such.

Nanosystems:

Drexler goes into deep details and lots of math about how nanotech might work, focusing nearly all of the book on individual devices that would operate in controlled environments and more like RL robots in that they are fixed to a location and materials and components pass by them via some form of conveyor system rather than free floating nanobots moving themselves around.

Putting these together, Drexler does initially talk about using free moving nanobots, but these are still operating in an enclosed environment. While he does mention what has come to be called 'grey goo' it was first in the context of a thought experiment intended to demonstrate the power of exponential growth and self-replicating technology - not as a serious threat or way that nanotech would work (unless solar system masses of chemicals are something we have lying around and I just missed the meeting? ). He does mention the danger of self replicating tech (plants) based on nano, which could be seen as a kind of grey goo - but again he doesn't spend much time on it and he definitely doesn't describe it in detail or make it his main point - the popular imagination of the general population has done that by fixating on this one aspect and running with it.

In later works Drexler goes out of his way to argue against grey goo scenarios and while he again depicts more 'free moving' nanobots, they are again operating in a controlled environment of a vat or tank.

By the time he gets to Nanosystems, Drexler isn't talking about nanobots much at all and talks almost exclusively in terms of controlled environment 'desktop factories' - a theme he continues with in later years from his website in which he devotes some articles to the convergent assembly type systems that Rynn mentioned earlier.

The upshot of all this is that Drexler never argued for the idea of free range nanobot swarms creating things out of whatever is handy in the natural environment, although he does acknowledge (briefly) that such are probably possible in principle - but that they would be very advanced designs (possibly matched or exceeded only by artificial immune systems in their level of sophistication) and there would be some question of why such would be needed for most cases. The popular imagination has however run with the free range nanobot idea and so people seem to think that's the only thing Drexler came up with - which is incorrect.

As mentioned, my personal copies of Drexler's works are in hardcopy, but I believe there are (or at least were) online copies available from which I can either pull direct quotes or provide links to if folks would like to look at the relevant sections for themselves. Or I can provide page references and some level of quotations (that's a lot of typing) if I can't locate the online versions.

Todd