Email exchange with Professor Moriarty

The following is an email exchange with Professor Phillip Moriarty discussing nanotechnology research. I want to thank him again for taking the time to answer my questions. His blog can be found here.

titotal:

Hey, I’m titotal, I enjoy your blog!  I’m a computational physics postdoc at [redacted], but in my spare time I’ve been skeptically looking into “AI extinction risk” for my own blog at

A lot of people are worried about human extinction from superintelligent artificial intelligence, but the actual scenarios put forward often seem to involve extremely advanced nanotechnology, and more recently, something called “diamondoid bacteria”. See the following passage from Eliezer Yudkowsky last year:

My lower-bound model of "how a sufficiently powerful intelligence would kill everyone, if it didn't want to not do that" is that it gets access to the Internet, emails some DNA sequences to any of the many many online firms that will take a DNA sequence in the email and ship you back proteins, and bribes/persuades some human who has no idea they're dealing with an AGI to mix proteins in a beaker, which then form a first-stage nanofactory which can build the actual nanomachinery.  […]  The nanomachinery builds diamondoid bacteria, that replicate with solar power and atmospheric CHON, maybe aggregate into some miniature rockets or jets so they can ride the jetstream to spread across the Earth's atmosphere, get into human bloodstreams and hide, strike on a timer.

From googling around, the “diamondoid bacteria” seems to be a reference to  “diamondoid mechanosynthesis”. You seem to be the only person I can find that worked experimentally on the subject. But it seems like the research topic has been somewhat dead for a while. 

I’m wondering if you know what happened with diamondoid nanomachine research after your collaboration ended? Do you think DMS still has potential, or was it a dead end? Also, as a nanotech expert, do you find yudkowsky’s scenario above realistic? It seems kind of nuts to me!

Phillip Moriarty:

Hi, .

Thanks for getting in touch and apologies for the delay in replying – it’s been a hectic couple of weeks.

Your email is very timely. I’m giving a talk for a Foresight Molecular Systems Design (https://foresight.org/) workshop in September. My interest in diamondoid structures stemmed directly from a debate/argument with Chris Phoenix, who worked closely with Eric Drexler for a number of years: http://www.softmachines.org/wordpress/?p=70 (It’s remarkable that it’s coming up to twenty years since that debate…)

Diamond is a very, very difficult surface to work with. We spent ten months and got no more than a few, poorly resolved atomic force microscopy (AFM) images. We’re not alone. This paper -- https://journals.aps.org/prb/cited-by/10.1103/PhysRevB.81.201403 (also attached)-- was the first to show atomic resolution AFM of the diamond surface. (There’d previously been scanning tunnelling microscopy (STM) images and spectroscopy of the diamond (100) surface but given that the focus was on mechanical force-driven chemistry (mechanosynthesis), AFM is a prerequisite.) So we switched after about a year of that project (which started in 2008) to mechanochemistry on silicon surfaces – this was much more successful, as described in the attached review chapter.

We are a long, long, loooong way from the scenario Yudkowsky describes. For example, despite it being 33 years since the first example of single atom manipulation with the STM (the classic Eigler and Schweizer Nature paper where they wrote the IBM logo in xenon atoms), there’s yet to be a demonstration of the assembly of even a rudimentary 3D structure with scanning probes: the focus is on the assembly of structures by pushing, pulling, and/or sliding atoms/molecules across a surface. Being able to routinely pick up, and then drop, an atom from a tip is a much more complicated problem.

Marauding swarms of nanobots won’t be with us anytime soon.

All the very best,

Philip

P.S. It’s worth noting that the citations of the Phys Rev B paper on AFM imaging of H:C(100) don’t include even one other paper on AFM of that surface…

Philip Moriarty

titotal:

Hey, thank you so much for replying! 

Is it okay with you if I quote or relay this response on my blog? 

I find it fascinating that you managed to achieve those very cool results with Si, but it seems like only one team has even managed to image the diamond. Si and C are right on top of each other on the periodic table, why is it so hard to image one compared to the other? Is there some very expensive equipment out there that would be able to reliably image diamond, or would you have to wait for some future technology to be invented?

I definitely agree about the nanobot swarms! Do you think we could even get anything nanobot-adjacent in the near future, like a useful variant of the nanocar? 

Phillip Moriarty:

Hi,.

It’s absolutely fine to quote from our email exchanges at your blog.

A key issue with diamond is that tip preparation is tricky. On silicon, it’s possible to recover atomic resolution relatively straight-forwardly via the application of voltage pulses or by pushing the tip gently (or not so gently!) into the surface – the tip becomes silicon terminated. Diamond is rather harder than silicon and so once the atomicstic structure at the end is lost, it needs to be moved to a metal sample, recovered, and then moved back to the diamond sample. This can be a frsutratingly slow process.

Moveover, it takes quite a bit of work to prepare high quality diamond surfaces. With silicon, it’s much easier: pass a DC current through the sample, heat it up to ~ 1200 C, and cool it down to room temperature again. This process routinely produces large atomically flat terraces.

I’m very familiar with the nanocar work. For one, I know one of the members of the winning team, Leonhard Grill, quite well. I also included a brief description of the race in this: https://www.amazon.co.uk/Nanotechnology-Short-Introduction-Introuduction-Introductions/dp/0198841108

We’re still a very long way off anything that remotely looks like a Drexlerian/Freitas nanobot, I’m afraid, although there is a lot of exciting scope for rapid developments at the AI-nano interface.

titotal:

Excellent, thank you! I'll give that book a read.  

One last technical question that has been confusing me: What actually is "diamondoid"? Most definitions I see online strictly claim it's hydrocarbons with a specific structure built around adamantane cages, but on the molecular assembly webpage, they say it's much broader:

Diamondoid materials also may include any stiff covalent solid that is similar to diamond in strength, chemical inertness, or other important material properties, and possesses a dense three-dimensional network of bonds. Examples of such materials are carbon nanotubes (illustrated at right) or fullerenes, several strong covalent ceramics such as silicon carbide, silicon nitride, and boron nitride, and a few very stiff ionic ceramics such as sapphire (monocrystalline aluminum oxide) that can be covalently bonded to pure covalent structures such as diamond.

I've never heard of Aluminum oxide referred to as diamondoid before. Are there multiple definitions floating around, or is the website just wrong? 

Phillip Moriarty:

Hi.

My understanding of the term “diamondoid” is as given in the first line of the abstract of the attached paper: “The term “diamondoid” describes cage hydrocarbon molecules that are superimposable on the diamond lattice.”

It’s possible that the molecular manufacturing community – which, as you know, is often outside the mainstream – has redefined what they understand by “diamondoid.”

All the best,

Phillip Moriarty