Sunday, November 18, 2018

Book Review: Radical Abundance

Eric Drexler is the person who came up with the name "nanotechnology" and is probably the one most responsible for public awareness of the idea.  After a pretty long haitus he's published a new book and I thought I'd take a look but before I get to the new book I think I should provide some history.

Way back in 1986 Drexler published Engines of Creation.  In it he outlined a vision of a world remade by the ability to engineer chemicals the way we engineer widgets today, assembling them precisely using mechanical arms placing bits in position rather than waiting for the random thermal motion of molecules to bring parts into contact where they can stick.  In the book he envisioned tiny robots called assemblers constructed with atomic precision using tiny arms to assemble other devices - and also replicate themselves.  That ability to replicate could potentially be a big danger if an error in programming caused them to replicated without bound like a cancer.  The cells that make up our bodies are contained by having to have had a clear evolutionary path from point to point.  It took a billion years for mitochondria to evolve since that required multiple things adjusting in a cell at once.  There are quite plausibly ways to drastically increase the efficiency of self-replicating organisms that could be designed by engineers which evolution wouldn't find before the Sun consumes the Earth.  Specifically, you could have these nanobots made out of much stronger molecules and life could use and also, thanks to placing things deliberately rather than wait for random motion to put things into place, they could potentially replicate much more quickly.  So it's possible that, if you can make good enough self-replicating nanobots and they have a fault you might see them end up consuming Earth's biosphere and turning it into grey goo.

After this publication Drexler went off to do some doctorate work which he later published at Nanosystems in 1992.  Rather than conceptualizing molecular manufacturing in terms of tiny robots he wrote about it in terms of molecular factories and assembly lines.  There are a lot of advantages to this approach.  Encasing a molecule in a tube as some operation is done to it limits its range of thermal motion much more effectively than trying to hold it it at the end of an arm.  By having the structure of a conveyor line encode a sequence of operations you don't need a nano-scale general purpose computer which made up the bulk of the atoms in the back-of-the-envelope design for a nanobot in Engines of Creation.  And you don't have to worry about a factory replicating itself in the same way you do with a tiny robot.

And that brings us to Radical Abundance published in 2013.  The book is a policy book like Engines of Creation was but the engineering in it is very much all post Nanosystems; looking at construction in terms of assembly lines rather than craftsman nanobots.  There's also a large segment on the public perception of nanotechnology and how it has changed over time.  Because of excitement about nanotechnology in the late 90s and early 00s a lot of chemistry tried to re-brand itself as nanotechnology to absorb nanotechnology research dollars.  This would involve molecules smaller than 100nm created by normal thermal motion chemistry rather than through forcing molecules together with external guidance.

Additionally, a lot of the public thinks of nanotechnology in terms of tiny nanobots instead of in terms of factories made out of atomically precise parts.  This is, of course, because that's how Engines of Creation conceptualized it and because Engines is a much easier to read book than Nanosystems is.  I was expecting some sort of mea culpa from Drexler on the matter and maybe an explanation on what he'd gotten wrong in his first book.  But Radical Abundance never seems to let slip that the ideas Drexler now finds so annoying were spread by his younger self.  I think a section going into a bit of detail on why nanobots aren't workable would have been a useful addition to this book but Drexler just dismisses them here with eye rolling.

But because of these two ways in which the word "nanotechnology" no longer means what he intended it to back in '86 he is now promoting "Atomic Precision Manufacturing" or APM as a term for the technologies he's interested in.  I wish him good luck with that but I'm doubtful he'll succeed.

What seems more likely to succeed are attempts to build these "APM" capabilities, at least eventually.  Our science of the nanoscale is currently imperfect but engineering practice can let us proceed anyways.  It's very hard to look at a protien and figure out how it will fold when placed in water.  I currently have my desktop give some spare cycles to figuring out some medically important proteins.  But that doesn't mean we can't just design proteins to fold understandably if we're willing to be a bit less efficient than evolution is.  We don't understand how every molecular surface interacts but we can restrict ourselves to the surfaces we do understand.  We can't predict the exact strength of every structure but we can design in sufficient safety factors to cover our uncertainty.  There's a lot of scientific work being done pointing towards APM and Drexler gives a good high level over view of it.

I'm going to say that I don't have any firm idea of what sort of time scale progress on APM/nanotechnology will happen on.  But I think I'm persuaded that it will happen eventually.

And just because I saw it recently, here's A Capella Science's song about current research in nanobots.

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